Control of Emissions from Marine SI
and Small SI Engines, Vessels, and
Equipment
Draft Regulatory Impact Analysis
&EPA
United States
Environmental Protection
Agency
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Control of Emissions from Marine SI
and Small SI Engines, Vessels, and
Equipment
Draft Regulatory Impact Analysis
Assessment and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
v>EPA
NOTICE
This technical report does not necessarily represent final EPA decisions or
positions. It is intended to present technical analysis of issues using data
that are currently available. The purpose in the release of such reports is to
facilitate the exchange of technical information and to inform the public of
technical developments which may form the basis for a final EPA decision,
position, or regulatory action.
United States EPA420-D-07-004
Environmental Protection . ., „„.,
Agency April 2007
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Table of Contents
Executive Summary ES-1
CHAPTER 1: Industry Characterization
1.1 Manufacturers of Small SI Engines 1-1
1.2 Manufacturers of Marine Spark-Ignition Engines 1-2
1.3 Fuel System Components 1-6
CHAPTER 2: Air Quality, Health, and Welfare Concerns
2.1 Ozone 2-2
2.2 Paniculate Matter 2-17
2.3 Gaseous Air Toxics 2-37
2.4 Carbon Monoxide 2-40
2.5 Acute Exposure to Air Pollutants 2-43
CHAPTER 3: Emission Inventory
3.1 Overview of Small Nonroad and Marine SI Engine Emissions Inventory
Development 3-2
3.2 Baseline Emission Inventory Estimates 3-4
3.3 Contribution of Small Nonroad and Marine SI Engines to National Emissions
Inventories 3-19
3.4 Controlled Nonroad Small Spark-Ignition and Marine Engine Emission Inventory
Development 3-27
3.5 Projected Emissions Reductions from the Proposed Rule 3-34
3.6 Emission Inventories Used for Air Quality Modeling 3-43
CHAPTER 4: Feasibility of Exhaust Emission Control
4.1 General Description of Spark-Ignition Engine Technology 4-1
4.2 General Description of Exhaust Emission Control Technologies 4-8
4.3 Feasibility of Small SI Engine Standards 4-23
4.4 Feasibility of Outboard/Personal Watercraft Marine Engine Standards 4-41
4.5 Feasibility of Sterndrive/Inboard Marine Engine Standards 4-47
4.6 Feasibility of Standard for Marine Generator Sets 4-58
4.7 Test Procedures 4-59
4.8 Impacts on Safety, Noise, and Energy 4-72
APPENDIX 4A: Normalized Modal Emissions for a 7.4 L MPI SD/I 4-80
CHAPTER 5: Feasibility of Evaporative Emission Control
5.1 Diurnal Breathing Loss Evaporative Emissions 5-2
5.2 Running Loss Emissions 5-25
5.3 Fuel Tank Permeation 5-29
5.4 Fuel/Vapor Hose Permeation 5-67
5.5 Other Evaporative Emissions 5-86
5.6 Evaporative Emission Test Procedures 5-88
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5.7 Impacts on Noise, Energy, and Safety 5-106
APPENDIX 5A: Diurnal Temperature Traces 5-109
APPENDIX 5B: Emission Results for Small SI Equipment Fuel Tanks Showing Effect of
Venting on Diffusion 5-112
APPENDIX 5C: Diurnal Emission Results: Canister and Passive-Purge 5-117
APPENDIX 5D: Material Properties of Common Fuel System Materials 5-118
APPENDIX 5E: Diurnal Test Temperature Traces 5-122
CHAPTER 6: Costs of Control
6.1 Methodology 6-1
6.2 Exhaust Emission Control Costs for Small SI Engines 6-2
6.3 Exhaust Emission Control Costs for Outboard and Personal Watercraft Engines ... 6-43
6.4 Exhaust Emission Control Costs for Sterndrive/Inboard Marine Engines 6-56
6.5 Evaporative Emission Control Costs for Small SI Equipment 6-64
6.6 Costs of Evaporative Emission Controls for Marine Vessels 6-78
6.7 Cost Sensitivity Analysis 6-91
CHAPTER 7: Cost Per Ton
7.1 30-Year Net Present Value Cost effectiveness 7-1
7.2 Results 7-2
CHAPTER 8: Cost-Benefit Analysis
8.1 Overview 8-1
8.2 Air Quality Impacts 8-8
8.3 PM-Related Health Benefits Estimation - Methods and Inputs 8-10
8.4 Benefits Analysis Results for the Proposed Standards 8-17
8.5 Unquantified Health and Welfare Effects 8-20
8.6 Methods for Describing Uncertainty 8-23
8.7 Health-Based Cost Effectiveness Analysis 8-35
8.8 Comparison of Costs and Benefits 8-36
CHAPTER 9: Economic Impact Analysis
9.1 Overview and Results 9-1
9.2 Economic Methodology 9-16
9.3 EIM Data Inputs and Model Solution 9-36
9.4 Methods for Describing Uncertainty 9-64
Appendix 9A: Impacts on Small SI Markets 9-72
Appendix 9B: Impacts on Marine SI Markets 9-90
Appendix 9C: Time Series of Social Cost 9-102
Appendix 9D: Overview of Model Equations and Calculation 9-106
Appendix 9E: Elasticity Parameters for Economic Impact Modeling 9-111
Appendix 9F: Derivation of Supply Elasticity 9-124
Appendix 9G: Initial Market Equilibrium - Price Forecasts 9-126
Appendix 9H: Sensitivity Analysis 9-128
CHAPTER 10: Small-Business Flexibility Analysis
10.1 Overview of the Regulatory Flexibility Act 10-1
10.2 Need for the Rulemaking and Rulemaking Objectives 10-2
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Draft Regulatory Impact Analysis
10.3 Definition and Description of Small Entities 10-3
10.4 Summary of Small Entities to Which the Rulemaking Will Apply 10-5
10.5 Related Federal Rules 10-6
10.6 Projected Reporting, Recordkeeping, and Other Compliance Requirements 10-7
10.7 Regulatory Alternatives 10-8
10.8 Projected Economic Effects of the Proposed Rulemaking 10-20
CHAPTER 11: Regulatory Alternatives
11.1 Identification of Alternative Program Options 11-1
11.2 Cost per Engine 11-7
11.3 Emission Reduction 11-18
11.4 Cost Effectiveness 11-20
11.5 Summary and Analysis of Alternative Program Options 11-21
APPENDIX 11 A: Emission Factors for the Less Stringent Alternative 11-26
APPENDIX 1 IB: Emission Factors for the More Stringent Alternative 11-27
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Executive Summary
Executive Summary
The Environmental Protection Agency (EPA) is proposing requirements to reduce emissions
of hydrocarbon (HC) and oxides of nitrogen (NOx) from nonroad small spark ignited engines
below 19kW ("Small SI engines") and marine spark ignited engines ("Marine SI engines"). This
proposed rule includes exhaust and evaporative emission standards for these engines as well as
related gasoline fuel tanks and fuel lines.
This executive summary describes the relevant air-quality issues, highlights the new exhaust
and evaporative emission standards, and gives an overview of the analyses in the rest of this
document.
Air Quality Background and Environmental Impact of the Proposed Rule
Emissions from Small SI engines and equipment and Marine SI engines and vessels
contribute to a number of serious air pollution problems and will continue to do so in the future
absent further reduction measures. Such emissions lead to adverse health and welfare effects
associated with ozone, paniculate matter (PM), NOx, volatile organic compounds (VOC),
including toxic compounds, and carbon monoxide (CO). These emissions also cause significant
public welfare harm, such as damage to crops, eutrophication, and regional haze.
Millions of Americans continue to live in areas with unhealthy air quality that may endanger
public health and welfare. As of October 2006 approximately 157 million people live in the 116
areas that are designated as nonattainment for the 8-hour ozone National Ambient Air Quality
Standards (NAAQS). In addition, approximately 88 million people live in areas that are
designated as nonattainment for the PM2.5 NAAQS. Federal, state, and local governments are
working to bring ozone and PM levels into attainment with the NAAQS. The reductions
included in this proposed rule will be useful to states in attaining and maintaining the ozone, CO,
and PM NAAQS.
In 2001, emissions from land-based nonroad Small SI engines and Marine SI
engines were estimated to be about 28 percent of the total mobile-source inventory of VOC
emissions and 1 percent of the NOx inventory. As presented in Figures 1 and 2, this rule assures
NONROAD inventories from rules to date are maintained or continue to decrease.
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Draft Regulatory Impact Analysis
Figure 1: Small SI VOC+NOx NONROAD Inventories for Baseline and
Phase 3 Control (Exhaust plus Evaporative)
in
c
o
1,400,000
1,200,000
1,000,000
800,000
600,000
400,000
200,000
0
2000
2040
Figure 2: Marine SI VOC+NOx NONROAD Inventories for Baseline
and Phase 3 Control (Exhaust plus Evaporative)
1 900 000 -i
1 000 000 -
800 000
c 600 000 -
O
400 000
900 000
n
\
V
v —
x^
^^^~^__
2000 2010 2020
Year
2030 2040
ES-2
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Executive Summary
Proposed Exhaust and Evaporative Emission Standards
Tables 1 through 4 show the exhaust and evaporative emission standards and when they are
proposed to apply. For Small SI engines, the standards are expected to require the use of
aftertreatment systems with some use of electronic fuel injection in Class II engines. As shown
in Tables 1 through 4, we are phasing in many of the standards over time to address
considerations of lead time, workload, and overall feasibility. In addition, the proposed rule
includes other provisions designed to address the transition to meeting the standards.
Table 1: Small SI Engine HC+NOx Exhaust Emission Standards and Schedule
Engine Class
Class I (80cc-225cc)
Class I (<80cc)
Class II
Model Year
2012
2012
2011
HC+NOx
[g/kW-hr]
10.0
Handheld standards
8.0
C0a
[g/kW-hr]
610
Handheld
standards
610
5 g/kW-hr CO for Small SI engines powering marine generators.
Table 2: Small SI Equipment Evaporative Emission Standards and Schedule
Standard Level
Handheld
Class I
Class II
Fuel Line
Permeation
15
g/m2/day
2012a
2008
2008
Tank
Permeation
1.5
g/m2/day
2009-20 13b'c
2012
2011
Diffusion
0.80 g/day
NA
2012
2011
Running
Loss
Design
Standard
NA
2012
2011
General Evaporative
Requirements
Design standards and
good engineering
judgment
2010
2012
2011
a 2013 for small-volume families; cold weather applications are excluded.
b 2.5 g/m2/day for structurally integrated nylon fuel tanks.
0 2009 for families certified in California, 2013 for small-volume families, 2010 for remaining families.
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Draft Regulatory Impact Analysis
Table 3: Marine SI Engine HC+NOx Exhaust Standards and Schedule
OB/PWCac
SD/PC
Engine Power
<40kW
>40kW
all
Model Year
2009
2009
2009
HC+ NOx [g/kW-hr]
28-0.3 xPb
16
5
CO
[g/kW-hr]
500-5. OxPb
300
75
a Seeking comment on modest phase-in for these new standards.
b P = maximum engine power in kilowatts (kW).
0 SD/I and OB/PWC also have NTE requirements; seeking comment on alternative standards for high-performance
engines (>373kW).
Table 4: Marine SI Engine Evaporative Emissions Standards and Schedule
Standard Level
Portable Tanks
PWC
Other Installed Tanks
Fuel Line
Permeation
15
g/m2/day
2009
2009
2009
Tank
Permeation
1.5 g/m2/day
2011
2011
2012
Diurnal
0.40
g/gal/day
2009a
2009
2010b
General Evaporative
Requirements
Design standards and good
engineering judgment
2009
2009
2010
a Design standard.
b Fuel tanks installed in non-trailerable boats (> 26 ft. in length) may meet a standard of 0.16 g/gal/day over an
alternative test cycle.
EPA has also taken steps to ensure that engines built to these standards achieve more
accurate emissions reductions and is upgrading the test requirements to those listed in
40CFR1065 as outlined in Preamble Section IX General Test Procedures.
Feasibility of Meeting the Proposed Small SI Engine Exhaust Emission Standards
Since 1997, exhaust emission control development for Small SI engines has concentrated on
engine redesign including carburetor design, improved engine combustion and engine cooling.
The primary technical focus of the proposed new emission standards will be engine upgrades as
needed, catalyst application to the majority of Small SI engines and electronic fuel injection on
some Class II engines. Related information is in Chapter 4.
We are proposing new, more stringent exhaust HC+NOx standards for Class I and II Small
SI engines. We are also proposing a new CO standard for Small SI engines used in marine
ES-4
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Executive Summary
generator applications. The standards differ by engine size. Class I engines have a total engine
displacement of < 225cc. Class II engines have a total engine displacement of >225cc.
In the 2005 model year, manufacturers certified over 500 Class I and II engine families to the
Phase 2 standards using a variety of engine designs and emission control technology. All Class I
engines were produced using carbureted air-fuel induction systems and are air cooled. An
extremely small number of engines used catalyst-based emission control technology. Similarly,
Class II engines were predominantly carbureted and air cooled. A limited number of these
engines used catalyst technology, electronic engine controls and fuel injection, and/or water
cooling.
The market focus has a large part to play in the engine design and quality. The large number
of residential and commercial applications have led to a wide variety of engine qualities and
designs in the marketplace today. Some of the more durable engine designs already incorporate
the base design requirements needed to incorporate a catalyst to meet the Phase 3 emission
standards. In addition, several engine families in both classes are currently certified at levels that
would comply with the proposed Phase 3 standards.
Based on our own testing of advanced technology for these engines, our engineering
assessments, and statements from the affected industry, we believe the proposed requirements
will lead many engine manufacturers to adopt exhaust aftertreatment technology using
catalyst-based systems. Other likely engine changes include improvements in engine designs,
cooling system designs and fuel delivery systems. The addition of electronic controls and/or fuel
injection systems to some Class II engine families may obviate the need for catalytic
aftertreatment, with the most likely candidates being multi-cylinder engine designs.
Information herein on the feasibility assessment of exhaust emissions on Small SI engines
includes the emission evaluation of current product and advanced technology engines. Areas
covered include laboratory and field evaluations, review of patents of existing catalyst/muffler
designs for Class I engines, discussions with engine manufacturers and suppliers of emission
control-related engine components regarding recent and expected advances in emissions
performance, and an analysis of catalyst/muffler units that were already in mass production by an
original equipment manufacturer for use on European walk-behind lawn mowers.
EPA used this information to design, build and emission test prototype catalyst-based
emission control systems that were capable of effectively and safely achieving the proposed
Phase 3 emission standards on both Class I and Class II engines. Chapter 4 projects that in some
cases manufacturers of Class I and Class II engines may need to improve the durability of their
basic engine designs, cooling system designs, ignition systems, or fuel metering systems for
some engines in order to comply with the Phase 3 emission regulations over the useful life. EPA
also built and tested electronic fuel injection systems on two twin cylinder Class II engines and
emission tested them with and without catalysts. EFI improves the management of air-fuel
mixtures and ignition spark timing and each of the engines achieved the requisite emission limit
for HC+NOx (e.g., 8.0 g/kW-hr). Based on this work and information from one manufacturer of
emission controls, we believe that either a catalyst-based system or electronic engine controls
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Draft Regulatory Impact Analysis
appear sufficient to meet the standard. Nonetheless, some applications may require the use of
both technologies. Manufacturers adopting the EFI approach will likely realize other advantages
such as easier starting, more stable and reliable engine operation, and reduced fuel consumption.
We also used the information and the results of our engine testing to assess the potential need
for improvements to engine, cooling and fuel system designs. A great deal of this effort was
conducted in association with our more in-depth study regarding the efficacy and safety of
implementing advanced exhaust emission controls on Small SI and recreational Marine SI
engines, as well as new evaporative requirements for these engines, equipment, and vessels. The
results of that study are also discussed in Chapter 4.
There are a number of Class II engines that use gaseous fuels (i.e., liquid propane gas or
compressed natural gas). Based on our engineering evaluation of current and likely emission
control technology for these engines, we conclude that these engines will use catalysts, or larger
catalysts than current, in order to achieve the proposed Phase 3 HC+NOx standard. Some
engines currently meet the Phase 3 emission standards.
Regarding the marine generator CO standard, two manufacturers that produce the majority of
marine generators have announced that as a result of boat builder demand, they are converting
their marine generator product lines to new designs which can achieve more than a 99 percent
reduction in CO emissions in order to reduce the risk of CO poisoning. These low CO emission
designs used closed-loop electronic fuel injection and catalytic control on engines which are
water cooled using the lake or sea water. Both of these manufacturers have certified some low
CO engines and have expressed their intent to convert their full product lines in the near future.
These manufacturers also make use of electronic controls to monitor catalyst function.
Feasibility of Meeting the Proposed Marine SI Exhaust Emission Standards
The technology is available for marine engine manufacturers to use to meet the proposed
standards. This technology is the same that manufacturers are anticipated to use to meet the
California ARB standards in 2008. For outboards and personal watercraft (OB/PWC) this
largely means extended use of lower-emitting engine technology widely used today. For
sterndrive and inboard (SD/I) marine engines, this means the use of catalytic converters in the
exhaust system. Chapter 4 includes detailed descriptions of low emission technologies for
marine engines, including emissions test data on these technologies.
OB/PWC
Over the past several years, manufacturers have demonstrated their ability to achieve
significant HC+NOx emission reductions from OB/PWC engines. This has largely been
accomplished through the introduction of two-stroke direct injection engines in some
applications and conversion to four-stroke engines. Current certification data for these types of
engines show that these technologies may be used to achieve emission levels significantly below
the existing exhaust emission standards. In fact, California has adopted standards requiring a 65
percent reduction beyond the current federal standards beginning in 2008.
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Executive Summary
Our own analysis of recent certification data shows that most four-stroke outboard engines
and many two-stroke direct injection outboard engines can meet the proposed HC+NOx
standard. Similarly, although PWC engines tend to have higher HC+NOx emissions,
presumably due to their higher power densities, many of these engines can also meet the
proposed HC+NOx standard. Although there is currently not a CO emission standard for
OB/PWC engines, OB/PWC manufacturers are required to report CO emissions from their
engines. These emissions are based on test data from new engines and do not consider
deterioration or compliance margins. Based on this data, all of the two-stroke direct injection
engines show emissions well below the proposed standards. In addition, the majority of
four-stroke engines would meet the proposed CO standards as well.
We therefore believe the proposed HC+NOx and CO emission standards can be achieved by
phasing out conventional carbureted two-stroke engines and replacing them with four-stroke
engines or two-stroke direct injection engines. This has been the market-driven trend over the
last five years. Chapter 4 compares current certification data to the proposed standards.
SD/I
Engine manufacturers can adapt readily available technologies to control emissions from
SD/I engines. Electronically controlled fuel injection gives manufacturers more precise control
of the air/fuel ratio in each cylinder, thereby giving them greater flexibility in how they calibrate
their engines. With the addition of an oxygen sensor, electronic controls give manufacturers the
ability to use closed-loop control, which is especially valuable when using a catalyst. In
addition, manufacturers can achieve HC+NOx reductions through the use of exhaust gas
recirculation. However, the most effective technology for controlling emissions is a three-way
catalyst in the exhaust stream.
In SD/I engines, the exhaust manifolds are water-jacketed and the water mixes with the
exhaust stream prior to exiting the vessel. Manufacturers add a water jacket to the exhaust
manifold to meet temperature-safety protocol. They route this cooling water into the exhaust to
protect the exhaust couplings and to reduce engine noise. Catalysts must therefore be placed
upstream of the point where the exhaust and water mix. This ensures the effectiveness and
durability of the catalyst. Because the catalyst must be small enough to fit in the exhaust
manifold, potential emission reductions are not likely to exceed 90 percent, as is common in
land-based applications. However, as discussed in Chapter 4, demonstration programs have
shown that emissions may be reduced by 70 to 80 percent for HC+NOx and 30 to 50 percent for
CO over the various modes of the proposed test cycle. Larger reductions, especially for CO,
have been achieved at lower speed operation.
Chapter 4 discusses issues that have been addressed in catalyst designs for SD/I engines such
as sustained operation at high load, potential saltwater effects on catalyst efficiency, and thermal
shock from cold water contacting a hot catalyst. Test programs have been performed to evaluate
catalysts in the laboratory and on the water. In addition, we are currently engaged in testing that
includes accumulating hours on catalyst equipped SD/I engines in boats operating in saltwater.
Earlier this year, one SD/I engine manufacturer began selling engines equipped with catalysts.
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Draft Regulatory Impact Analysis
They have certified their engines to the California ARB standards, and are selling their
catalyst-equipped engines nationwide. This manufacturer indicated that they have successfully
completed durability testing, including extended in-use testing on saltwater.
Feasibility of Meeting the Proposed Evaporative Emission Standards
There are many feasible control technologies that manufacturers can use to meet the
proposed evaporative emission standards. We have collected and will continue to collect
emission test data on a wide range of technologies for controlling evaporative emissions.
Chapter 5 presents a description of the evaporative emission sources which include permeation,
diurnal, running loss, hot soak, and refueling emissions. In addition, Chapter 5 presents
evaporative emission test data for current Small SI and marine fuel systems and on a wide range
of evaporative emission control technologies. Below is an overview of technologies that are
available for meeting the proposed evaporative emission standards.
Low-permeation fuel lines are in production today. One fuel line design, already used in some
marine applications, uses a thermoplastic layer between two rubber layers to control permeation.
This thermoplastic barrier may either be nylon or ethyl vinyl acetate (EVOH). Barrier
approaches in automotive applications include fuel lines with fluoroelastomers such as FKM and
fluoroplastics such as Teflon and THV. In addition to presenting data on low-permeation fuel
lines, Chapter 5 lists several fuel-system materials and their permeation rates. Molded rubber
fuel line components, such as primer bulbs and some handheld fuel lines, could meet the
standard by using a fluoroelastomer such as FKM.
Plastic fuel tanks used in Small SI and Marine SI applications can be molded using several
processes. While no fuel tank permeation control strategy will work for all production processes
and materials, there are multiple control strategies available for fuel tanks manufactured with
each of the molding processes. These molding processes include blow-molding, injection-
molding, thermoforming, rotational-molding, and hand built constructions (fiberglass).
Multi-layer fuel tanks can be formed using most of these molding processes. These fuel tank
constructions include a barrier layer of a low permeation material such as ethylene vinyl alcohol
(EVOH) or nylon. This technology has been used in blow-molded fuel tanks for automotive
applications for many years and can achieve emission levels well below the proposed standard.
For thermoformed fuel tanks, a similar barrier formed into the plastic sheet that is later molded
into a fuel tank. Rotationally-molded fuel tanks can be produced with an inner barrier layer such
as nylon or polybutylene terephthalate (PBT). As an alternative, in the blow-molding process, a
low-permeable resin can be blended with polyethylene and extruded it with a single screw.
Although the barrier is not continuous, this strategy can still be used to meet the proposed
permeation standard. A similar strategy may be used for fiberglass fuel tank where the barrier
material is clay nanocomposites. Finally, fuel tanks may be formed entirely out of a low
permeation material such as nylon or an acetal copolymer. Many fuel tanks used with handheld
equipment use nylon fuel tanks.
Another approach to producing fuel tanks that meet the proposed permeation standards
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Executive Summary
would be to create permeation barrier through a post-processing step. Regardless of the molding
process, another type of low-permeation technology for high-density polyethylene fuel tanks
would be to treat the surfaces with a barrier layer. Two ways of achieving this are known as
fluorination and sulfonation. In these processes, the tanks are exposed to a gas which forms a
permeation barrier on the surfaces of the fuel tank. Either of these processes can be used to
reduce gasoline permeation by more than 95 percent. Additionally, a barrier layer can be put
onto a fuel tank with the use of an epoxy barrier coating.
There are several technologies that can be used to reduce diurnal emissions from marine fuel
tanks. The simplest approach is to seal the fuel tank. Portable fuel tanks currently use manual
valves that can be closed to seal the fuel tank. PWC typically use sealed fuel systems with
pressure relief valves that open at pressures ranging from 0.5 to 4.0 psi. For other vessels with
installed fuel tanks, manufacturers have commented that even 1.0 psi of pressure would be too
high for their applications. Through the use of a carbon canister in the vent line, diurnal
emissions can be controlled from these fuel tanks without creating significant pressure in the fuel
tank. With this technology, vapor generated in the tank is vented to a canister containing
activated carbon. The fuel tank must be sealed such that the only venting that occurs is through
the carbon canister. The activated carbon collects and stores the hydrocarbons. The activated
carbon bed in the canister is refreshed by purging the vapors with air flow. The proposed
standard is based on the air flow being generated by the natural breathing of the fuel tank as it
heats and cools.
Running loss emissions can be controlled from Small SI equipment by sealing the fuel cap
and routing vapors from the fuel tank to the engine intake. In doing so, vapors generated by heat
from the engine will be burned in the engine=s combustion chamber. It may be necessary to use
a valve or limited-flow orifice in the purge line to prevent too much fuel vapor from reaching the
engine and to prevent liquid fuel from entering the line if the equipment flips over. Depending
on the configuration of the fuel system and purge line, a one-way valve in the fuel cap may be
desired to prevent a vacuum in the fuel tank during engine operation. We anticipate that a
system like this would eliminate running loss emissions. However, higher temperatures during
operation and the additional length of vapor line would slightly increase permeation.
Considering these effects, we still believe that the system described here would reduce running
losses from Small SI equipment by more than 90 percent. Other approaches would be to move
the fuel tank away from heat sources or to use heat protection such as a shield or directed air
flow.
Many manufacturers today use fuel caps that by their design effectively limit the diffusion of
gasoline from fuel tanks. In fact, the proposed diffusion emission standard for Small SI
equipment is based to a large degree on the diffusion control capabilities of these fuel caps. As
discussed in Chapter 5, venting a fuel tank through a tube (rather than through an open orifice)
also greatly reduces diffusion. We have conducted additional testing with short,
narrow-diameter vent lines which shows that these lines provide enough resistance to diffusion
to meet the proposed emission standards.
Estimated Costs and Cost-Effectiveness for Small SI Engines and Equipment
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Draft Regulatory Impact Analysis
There are approximately 410 nonroad equipment manufacturers using Small SI engines in
over a thousand different equipment models. There are more than 50 engine manufacturers
certifying Small SI engine families for these applications. Fixed costs consider engine research
and development, engine tooling, engine certification, and equipment redesign. Variable costs
include estimates for new emission-control hardware. Near-term and long-term costs for some
example pieces of equipment are shown in Table 5. Also shown in Table 5 are typical prices for
each piece of equipment for reference. See Chapter 6 for detailed information related to our
engine and equipment cost analysis. The annualized cost for Small SI emission regulations are
$265 million without fuel savings and $203 million with fuel savings for exhaust only. For
evaporative and exhaust combined, the annualized cost for Small SI emission regulation are
$332 million without fuel savings and $218 with fuel savings.
Table 5: Estimated Costs for Several Example Pieces of Equipment ($2005)a
Over the Range of Useful Life Categories for Small SI Engines'3
Exhaust Near Term
Long Term
Evaporative Near Term
Long Term
Total (without fuel savings)
Near Term
Long Term
Total (with fuel savings)0
Near Term
Long Term
Estimated Equipment Price Range
Class I
$11 to $23
$9 to $15
$3.16
$2.29
$14 to $26
$11 to $17
$13 to $25
$10 to $16
$100-$2,800
Class II
$39 to $85
$22 to $47
$6.90
$5.30
$46 to $92
$27 to $52
$l-$48/$40-$86
-$18-$6/$21-$46
Engines w/ and w/o EFI
$300-$6800
Handheld
(Class III-V)
$0.30
$0.00
$0.82
$0.69
$1.12
$0.69
$0.72
$0.29
$210 avg
a Near-term costs include both variable costs and fixed costs; long-term costs include only variable costs
and represent those costs that remain following recovery of all fixed costs.
b Class I (125,250, or 500 hours), Class II (250, 500, or 1000 hours)
0 Class I, Class II and handheld have fuel savings from evaporative measures. Class II engines with EFI have fuel
savings of $39 based on the lifetime savings in the use of a residential ride on mower. There are no fuel savings
related to compliance with the exhaust emission standard for Class I, handheld, or Class II engines without EFI.
Chapter 6 presents aggregate costs of compliance for the proposed exhaust and evaporative
emission standards for Small SI engines. Table 6 presents the annualized aggregate costs and
fuel savings for the period from 2008-2037. The annualized fuel savings for Small SI engines
are due to reduced fuel costs form the sue of electronic fuel injection on Class II engines as well
as fuel savings from evaporative measures on all Small SI engines.
Table 6: Estimated Annualized Cost to manufacturers and Annualized Fuel Savings for
Small SI Engines and Equipment at a 7% Discount Rate (2005$)
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Executive Summary
Exhaust
Evaporative
Aggregate
Annualized Cost to Manufacturers
(millions/yr)
$267
$67
$334
Annualized fuel savings
(millions/yr)
$63
$52
$115
Chapter 7 describes the cost effectiveness analysis. In this analysis, the aggregate costs of
compliance are determined for the period 2008-2037. The discounted aggregate costs for the
period are divided by the discounted aggregate HC_NOx emission reductions.
Table 7: Aggregate Cost per Ton for Small SI Engines and Equipment
2008-2037 Net Present Values at 7% Discount Rate ($2005)
Pollutant
NOx+HC
7%
Aggregate Discounted
Lifetime Cost per ton
Without Fuel Savings
$1450
Aggregate Discounted
Lifetime Cost per ton
With Fuel Savings
$950
Estimated Costs and Cost-Effectiveness for Marine SI Engines
According to the US Coast Guard there are well over a thousand different boat builders
using Marine SI engines. There are about 10 engine manufacturers certifying to the current
OB/PWC exhaust emission standards. We have identified more than 30 companies
manufacturing SD/I marine engines. Fixed costs consider engine research and development,
engine tooling, engine certification, and equipment redesign. Variable costs include estimates
for new emission-control hardware. Near-term and long-term costs for three different Marine SI
applications are shown in Table 8. Also shown in Table 8 are typical prices for these types of
marine vessels. See Chapter 6 for detailed information related to our engine and equipment cost
analysis.
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Draft Regulatory Impact Analysis
Table 8: Estimated Average Incremental Costs for SI Marine Engines and Vessels ($2005)a
Engine Category
(Fuel Storage System)
Exhaust
Near Term
Long Term
Evaporative
Near Term
Long Term
Total (without fuel savings)
Near Term
Long Term
Total (with fuel savings)
Near Term
Long Term
Estimated Vessel Price Range
Outboard
(Portable)
$284
$219
$12
$8
$296
$227
$201
$132
$10,000-50,000
PWC
(Installed)
$359
$272
$17
$11
$376
$283
$221
$128
$6,000-12,000
SD/I
(Installed)
$362
$274
$74
$62
$436
$336
$285
$185
$20,000-200,000
a Near-term costs include both variable costs and fixed costs; long-term costs include only variable costs and
represent those costs that remain following recovery of all fixed costs.
Chapter 6 presents aggregate costs of compliance for the proposed exhaust and evaporative
emission standards for Marine SI engines. Table 9 presents the annualized aggregate costs and
fuel savings for the period from 2008-2037. The annualized fuel savings for Marine SI engines
are due to reduced fuel costs from the use of more fuel efficient engines as well as fuel savings
from evaporative measures.
Table 9: Estimated Annualized Cost to Manufacturers and Annualized Fuel Savings for
Marine SI Engines and Vessels at a 7% Discount Rate (2005$)
Exhaust
Evaporative
Aggregate
Annualized Cost to Manufacturers
(millions/yr)
$141
$26
$167
Annualized Fuel Savings
(millions/year)
$67
$25
$92
Chapter 7 describes the cost effectiveness analysis. In this analysis, the aggregate costs of
compliance are determined for the period 2008-2037. The discounted aggregate costs for the
period are divided by the discounted aggregate HC+NOx emission reductions over that same
period. Table 10 presents the cost per ton estimates with and without fuel savings.
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Executive Summary
Table 10: Aggregate Cost per Ton for SI Marine Engines and Vessels
2008-2037 Net Present Values at 7% Discount Rate ($2005)
Pollutant
NOx+HC
7%
Aggregate Discounted
Lifetime Cost per ton
Without Fuel Savings
$780
Aggregate Discounted
Lifetime Cost per ton
With Fuel Savings
$350
Economic Impact Analysis
We prepared a draft Economic Impact Analysis estimate the market and social welfare
impacts of the proposed standards. This analysis can be found in Chapter 9. According to this
analysis, the average price of a Marine SI engine in 2030 is projected to increase by less than 2
percent ($195) as a result of the proposed standards, and the average price of a Marine SI vessel
is projected to increase by between 0.5 percent and 2.1 percent ($160 to $496), depending on the
type of vessel. The average price of a Small SI engine in 2030 is projected to increase by about
9.1 percent ($17), and the average price of Small SI nonhandheld equipment is projected to
increase by between 0.3 percent and 5.6 percent ($10 to $25), depending on equipment class.
Changes in quantity produced are expected to be small, at less than 2 percent. The exceptions
are PWC (4.2 percent) and Class II equipment (2.8 percent).
The total social costs of the program in 2030 are estimated to be $241 million. This includes
$569 million of direct compliance costs and $327 million on fuel savings for the end users of
these products. Overall, the consumers of Marine SI vessels and Small SI equipment are
expected to bear the majority of the costs of complying with the program: 66 percent of the
Marine SI program social costs in 2030, and 79 percent of the Small SI program social costs.
However, when the fuel savings are considered, the social costs burden for consumers of Marine
SI equipment becomes a net benefit (the fuel savings are greater than the compliance costs of the
program), while the end-user share of the Small SI program drops to 62 percent.
Benefits
We estimate that the requirements in this proposal will result in substantial benefits to
public health and welfare and the environment, as described in Chapter 8. EPA typically
quantifies PM- and ozone-related benefits in its regulatory impact analyses (RIAs) when
possible. In the analysis of past air quality regulations, ozone-related benefits have included
morbidity endpoints and welfare effects such as damage to commercial crops. EPA has not
recently included a separate and additive mortality effect for ozone, independent of the effect
associated with fine paniculate matter. For a number of reasons, including 1) advice from the
Science Advisory Board (SAB) Health and Ecological Effects Subcommittee (HEES) that EPA
consider the plausibility and viability of including an estimate of premature mortality associated
with short-term ozone exposure in its benefits analyses and 2) conclusions regarding the
scientific support for such relationships in EPA's 2006 Air Quality Criteria for Ozone and
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Draft Regulatory Impact Analysis
Related Photochemical Oxidants (the CD), EPA is in the process of determining how to
appropriately characterize ozone-related mortality benefits within the context of benefits
analyses for air quality regulations. As part of this process, we are seeking advice from the
National Academy of Sciences (NAS) regarding how the ozone-mortality literature should be
used to quantify the reduction in premature mortality due to diminished exposure to ozone, the
amount of life expectancy to be added and the monetary value of this increased life expectancy
in the context of health benefits analyses associated with regulatory assessments. In addition, the
Agency has sought advice on characterizing and communicating the uncertainty associated with
each of these aspects in health benefit analyses.
Since the NAS effort is not expected to conclude until 2008, the agency is currently
deliberating how best to characterize ozone-related mortality benefits in its rulemaking analyses
in the interim. For the analysis of the proposed locomotive and marine standards, we do not
quantify an ozone mortality benefit. So that we do not provide an incomplete picture of all of the
benefits associated with reductions in emissions of ozone precursors, we have chosen not to
include an estimate of total ozone benefits in the proposed RIA. By omitting ozone benefits in
this proposal, we acknowledge that this analysis underestimates the benefits associated with the
proposed standards. Our analysis, however, indicates that the rule's monetized PM2.5 benefits
alone substantially exceed our estimate of the costs.
The PM2 5 benefits are scaled based on relative changes in direct PM emissions between this
rule and the proposed Clean Air Nonroad Diesel (CAND) rule. As explained in Section 8.2.1,
the PM2 5 benefits scaling approach is limited to those studies, health impacts, and assumptions
that were used in the proposed CAND analysis. As a result, PM-related premature mortality is
based on the updated analysis of the American Cancer Society cohort (ACS; Pope et al., 2002).
However, it is important to note that since the CAND rule, EPA's Office of Air and Radiation
(OAR) has adopted a different format for its benefits analysis in which characterization of the
uncertainty in the concentration-response function is integrated into the main benefits analysis.
Within this context, additional data sources are available, including a recent expert elicitation
and updated analysis of the Six-Cities Study cohort (Laden et al., 2006). Please see the PM
NAAQS RIA for an indication of the sensitivity of our results to use of alternative
concentration-response functions.
The analysis presented here assumes a PM threshold of 3 |_ig/m3, equivalent to background.
Through the RIA for the Clean Air Interstate Rule (CAIR), EPA's consistent approach had been
to model premature mortality associated with PM exposure as a nonthreshold effect; that is, with
harmful effects to exposed populations modeled regardless of the absolute level of ambient PM
concentrations. This approach had been supported by advice from EPA's technical peer review
panel, the Science Advisory Board's Health Effects Subcommittee (SAB-HES). However, EPA's
most recent PM2 5 Criteria Document concludes that "the available evidence does not either
support or refute the existence of thresholds for the effects of PM on mortality across the range
of concentrations in the studies," (p. 9-44). Furthermore, in the RIA for the PM NAAQS we
used a threshold of 10 |_ig/m3 based on recommendations by the Clean Air Scientific Advisory
Committee (CAS AC) for the Staff Paper analysis. We consider the impact of a potential,
assumed threshold in the PM-mortality concentration response function in Section 8.6.2. The
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Executive Summary
monetized benefits associated with the proposed program are presented in Table 11. These
estimates are in year 2005 dollars.
We estimate that in 2030, the annual PM-related emission reductions associated with the
proposed standards would annually prevent 450 premature deaths (based on the ACS cohort
study), 52,000 work days lost, 500 hospital admissions, and 310,000 minor restricted-activity
days.
Table 11: Estimated Monetized PM-Related Health Benefits of the Proposed Standards
Using a 3% discount rate
Using a 7% discount rate
Total Benefits1' b'c (billions 2005$)
2020
$2.1 +B
$1.9+B
2030
$3.4 +B
$3.1+B
a Benefits include avoided cases of mortality, chronic illness, and other morbidity health endpoints. PM-related
mortality benefits estimated using an assumed PM threshold at background levels (3 |ig/m3). There is uncertainty
about which threshold to use and this may impact the magnitude of the total benefits estimate. For a more detailed
discussion of this issue, please refer to Section 8.6.
b For notational purposes, unquantified benefits are indicated with a "B" to represent the sum of additional monetary
benefits and disbenefits. A detailed listing of unquantified health and welfare effects is provided in Table 8.1-2 of
the RIA.
0 Results reflect the use of two different discount rates: 3 and 7 percent, which are recommended by EPA's
Guidelines for Preparing Economic Analyses and OMB Circular A-4. Results are rounded to two significant digits
for ease of presentation and computation.
Impact on Small Businesses
Chapter 10 discusses our Initial Regulatory Flexibility Analysis, which evaluates the
potential impacts of the proposed emission standards on small entities. As a part of this analysis,
we interacted with several small entities representing the various affected sectors and convened a
Small Business Advocacy Review (SBAR) Panel to gain feedback and advice from these
representatives. The small entities that participated in the process included engine
manufacturers, equipment manufacturers, vessel manufacturers, fuel tank manufacturers, and
fuel hose manufacturers. The feedback from these companies was used to develop regulatory
options which could address the impacts of the rule on small businesses. Small entities raised
general concerns related to potential difficulties and costs of meeting the proposed standards.
The SBAR Panel consisted of representatives from EPA, the Office of Management and
Budget, and the Small Business Administration. The Panel developed a wide range of regulatory
flexibilities to mitigate the impacts of the proposed standards on small entities, and
recommended that we propose and seek comment on the flexibilities. Chapter 10 discusses the
flexibilities recommended by the Panel, the regulatory alternatives we considered in developing
the proposal, and the flexibilities we are proposing. We have proposed several provisions that
give affected small entities several compliance options aimed specifically at reducing their
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Draft Regulatory Impact Analysis
compliance burdens. In general the options are similar to small entity provisions adopted in
prior rulemakings where EPA set standards for other types of nonroad engines. The proposed
provisions include extra lead time for the proposed standards, reduced testing requirements for
demonstrating compliance with the standards, and hardship provisions to address significant
economic impacts and unusual circumstances related to the standards. These proposed
provisions are intended to reduce the burden on small entities that will be required to meet the
new emission standards when they are implemented.
Alternative Program Options
In developing the proposed emission standards, we considered several alternatives including
less and/or more stringent options. The paragraphs below summarize the information considered
in Chapter 11 of the Draft RIA.
Small SI Engines
For Small SI engines, we considered what was achievable with catalyst technology. Our
technology assessment work indicated that the proposed emission standards are feasible in the
context of provisions for establishing emission standards prescribed in section 213 of the Clean
Air Act. We also considered what could be achieved with larger, more efficient catalysts and
improved fuel induction systems. In particular, Chapter 4 of the Draft RIA presents data on
Class I engines with more active catalysts and on Class II engines with closed-loop control fuel
injection systems in addition to a catalyst. In both cases larger emission reductions were
achieved.
Based on this work we considered HC+NOx standards which would have involved a 50
percent reduction for Class I engines and a 65-70 percent reduction for Class II engines. Chapter
11 of the Draft RIA evaluates these alternatives, including an assessment of the overall
technology and costs of meeting more stringent standards. For Class I engines a 50 percent
reduction standard would require base engine changes not necessarily involved with the
standards we are proposing and the use of a more active catalyst. For Class II engines this would
require the widespread use of closed loop control fuel injection systems rather than carburetors,
some additional engine upgrades, and the use three-way catalysts. We believe it is not
appropriate at this time to propose more stringent exhaust emission standards for Small SI
engines. Our key concern is lead time. More stringent standards would require several years
(3-5) more lead time beyond the 2011 model year start date we are proposing for the program.
We believe it would be more effective to implement the Phase 3 standards we are proposing
today to achieve near-term emission reductions needed to reduce ozone precursor emissions and
to minimize growth in the Small SI exhaust emissions inventory in the post 2010 time frame.
More efficient catalysts, engine improvements, and closed loop electronic fuel injection could be
the basis for more stringent emission standards at some point in the future.
Marine SI Engines
For Marine SI engines, we considered a level of 10 g/kW-hr HC+NOx for OB/PWC engines
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Executive Summary
greater than 40 kW with an equivalent percent reduction below the proposed standards for
engines less than 40 kW. This second tier of standards could apply in the 2012 or later time
frame. Such a standard would be consistent with currently certified emission levels from a
significant number of four-stroke outboard engines. We have three concerns with adopting this
second tier of OB/PWC standards. First, while some four-stroke engines may be able to meet a
10 g/kW-hr standard with improved calibrations, it is not clear that all engines could meet this
standard without applying catalyst technology. As described in Section IV.H.3 of the preamble,
we believe it is not appropriate to base standards in this rule on the use of catalysts for OB/PWC
engines. The technology is yet to be adequately demonstrated. Second, certification data for
personal watercraft engines show somewhat higher exhaust emission levels, so setting the
standard at 10 g/kW-hr would likely require catalysts for many models. Third, two-stroke direct
injection engines operate with lean air-fuel ratios, so reducing NOx emissions with any kind of
aftertreatment is challenging.
Therefore, unlike the proposed standards for SD/I engines, we are not pursuing OB/PWC
standards that will require the use of catalysts. Catalyst technology would be necessary for
significant additional control of HC+NOx and CO emissions. While there is good potential for
eventual application of catalyst technology to OB/PWC engines, we believe the technology is
not adequately demonstrated at this point.
Evaporative Emission Controls
We considered both less and more stringent evaporative emission control alternatives for fuel
systems used in Small SI equipment and Marine SI vessels. Chapter 11 of the Draft RIA
presents details on this analysis of regulatory alternatives. The results of this analysis are
summarized below. We believe that the proposed permeation standards are reflective of
available technology and represent a step change in emissions performance. Therefore, we
consider the same permeation control scenario in the less stringent and more stringent regulatory
alternatives.
For Small SI equipment, we considered a less stringent alternative without running loss
emission standards for Small SI engines. However, we believe that controlling running loss and
diffusion emissions from non-handheld equipment is feasible at a relatively low cost. Running
loss emissions can be controlled by changing the fuel tank and cap venting scheme and routing
vapors from the fuel tank to the engine intake. Other approaches would be to move the fuel tank
away from heat sources or to use heat protection such as a shield or directed air flow. Diffusion
can be controlled by simply using a tortuous tank vent path, which is often used today on Small
SI equipment to prevent fuel splashing or spilling. These emission control technologies are
relatively straight-forward, inexpensive, and achievable in the near term. Not requiring these
controls would be inconsistent with section 213 of the Clean Air Act. For a more stringent
alternative, we considered applying a diurnal emission standard for all Small SI equipment. We
believe that passively purging carbon canisters could reduce diurnal emissions by 50 to 60
percent from Small SI equipment. However, we believe some important issues would need to be
resolved for diurnal emission control, such as cost, packaging, and vibration. The cost
sensitivity is especially noteworthy given the relatively low emissions levels (on a
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Draft Regulatory Impact Analysis
per-equipment basis) from such small fuel tanks.
For Marine SI vessels, we considered a less stringent alternative, where there would be no
diurnal emission standard for vessels with installed fuel tanks. However, installed fuel tanks on
marine vessels are much larger in capacity than those used in Small SI applications. Our
analysis indicates that traditional carbon canisters are feasible for boats at relatively low cost.
While packaging and vibration are also issues with marine applications, we believe these issues
have been addressed. Carbon canisters were installed on fourteen boats by industry in a pilot
program. The results demonstrated the feasibility of this technology. The proposed standards
would be achievable through engineering design-based certification with canisters that are very
much smaller than the fuel tanks. In addition, sealed systems, with pressure control strategies
would be accepted under the proposed engineering design-based certification. For a more
stringent scenario, we consider a standard that would require boat builders to use an actively
purged carbon canister. This means that, when the engine is operating, it would draw air through
the canister to purge the canister of stored hydrocarbons. However, we rejected this option
because active purge occurs infrequently due to the low hours of operation per year seen by
many boats. The gain in overall efficiency would be quite small relative to the complexity active
purge adds into the system in that the engine must be integrated into a vessel-based control
strategy. The additional benefit of an actively purged diurnal control system is small in
comparison to the cost and complexity of such a system.
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Industry Characterization
CHAPTER 1: Industry Characterization
The information contained in this chapter on the Small SI engine and Marine SI engine
industries was assembled by RTI International, a Health, Social and Economics Research firm in
cooperation with EPA. RTI prepared one report each on the Small SI and Marine SI industries,
"Industry Profile for Small Nonroad Spark Ignition Engines and Equipment"1 and "Industry
Profile for Marine SI Industry"2 report. The following sections provide a brief report overview.
The reader is encouraged to refer to the reports for greater detail. In addition, this chapter
includes an overview of production practices for fuel system component manufacturers. Chapter
10 provides information on the businesses that would be affected by the proposed standards.
1.1 Manufacturers of Small SI Engines
The nonroad spark-ignition (SI) industry includes a wide variety of handheld and
nonhandheld equipment. Nonhandheld equipment is powered mainly by four-stroke gasoline
engines; handheld equipment is powered mainly by two-stroke gasoline engines. Comprising
much of what the general public considers "lawn and garden (L&G) equipment," this industry
also produces significant numbers of generators, compressors, and construction and maintenance
equipment. The industry often refers to itself as the "outdoor power equipment" industry.
This profile provides background information on the engines and equipment that make up
the small nonroad SI industry, defined as those products rated less than or equal to 19 kilowatt
(kW) (roughly equivalent to 25 horsepower [hp]). This profile describes markets for engines and
equipment, and discusses their use in both consumer and commercial applications. In each
market, producers and consumers are described, along with product attributes and the effect of
those attributes on production cost and demand. The market analysis emphasizes assessing
suppliers' cost of production and industry structure, along with demanders' price responsiveness
and consumption alternatives.
The variety of products in this industry is usefully partitioned by both application
categories and engine type. Figure 1-1 illustrates the links between the market segments of the
Small SI engine supply chain included in the profile, from engine manufacturing and sale to
equipment production, and on to purchase by consumers and commercial customers. Although
more than 98 percent of total unit sales in the L&G equipment sector go to households, other
sectors' sales are dominated by commercial equipment. Because of the significantly higher prices
of commercial units, commercial sales represent a considerable share of the total value of
production.
It should be noted that there is a fair amount of vertical integration in the handheld
industry, with the same parent firm making both engines and the equipment in which those
engines are used. Handheld equipment includes string trimmers, leaf blowers, and chainsaws.
This situation is known as "captive" engine production; data on internal consumption of engines
and transfer prices are typically not available outside the firm. The makers of non-handheld
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Draft Regulatory Impact Analysis
engines typically sell their engines to independent equipment manufacturers in a merchant
engine market, where prices and quantities exchanged can be directly observed.
The industry profile for Small SI presents information on product characteristics,
supply-side considerations, consumer demand, and market structure for small nonroad SI
engines. The report also includes similar types of information on equipment markets, broken
down by application category. Considerations related to consumer and commercial markets are
included in the demand subsection of that section.
Figure 1-1: The Small Nonroad SI Industry
Consumers
C o m m e re ia I U s e rs
EquipmentMarkets
• Lawnmowers
Handheld Lawn and Garden
• Other Lawn and Garden
• Generators and Welders
• Compressors and Pumps
• Recreational Products
•Snow Blowers
• O (her S m a II S I
I m po rts
• Engines
• Equipment
S m a I
N onintegrated
E q u ip m e n t
M a n u fa c tu re rs
I Engine
• Class
•Size
M a rk e ts
M e re h a n t
E n g in e
M a n u fa c tu re rs
In te g ra te d
E q u ip m e n t
M a n u fa c t u re rs
C a ptiv e
E n g in e
M a n u fa c tu re rs
1.2 Manufacturers of Marine Spark-Ignition Engines
The Marine SI industry is dominated by recreational applications with some commercial
use and includes markets for several types of boats, personal watercraft (PWC), and SI engines
that power them. The industry profile presented in the "Industry Profile for Marine SI Industry"
report by RTI describes producers and consumers for each market segment; product attributes
and the effects of these attributes on production costs and demand are described as well. As part
of the market characterization, particular emphasis is placed on assessing suppliers' industrial
organization and cost of production and demanders' price responsiveness and substitution
possibilities. The Marine SI industry is divided into three applications areas: outboard (OB)
boats, sterndrive and inboard (SD/I) boats, and PWC.
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Industry Characterization
1.2.1 OB Boats
An OB boat is a vessel powered by one or more gasoline engines, which are located
outside the hull at the back of the boat. The engine and drive unit are combined in a single
package. An engine can easily be removed from the boat for inspection or repair, and it is quite
common for the boat owner to change engines during the life of the vessel. The OB boat
segment is the largest of the three application areas; in 2002, 213,000 units were sold, which is
more than the combined sales of SD/I and PWC.
The OB application area can be further divided into "recreational" and "luxury"
categories. The luxury category includes more-expensive vessels, for which the engine
constitutes only a small portion of the cost of the entire vessel. The NMMA distinguishes
between 14 types of OB vessels, 10 of which are considered recreational and 4 luxury.
1.2.2 SD/I Boats
SD/I vessels have an engine installed inside the hull of the vessel. An inboard vessel is a
boat in which the engine is located inside the hull at the center of the boat with a propeller shaft
going through the rear of the boat. A sterndrive (or inboard/outboard) vessel is a boat in which
the engine is located inside the hull at the back of the boat with a drive assembly couple directly
to the propeller, propeller shaft going through the rear of the boat. In contrast to OB vessels,
SD/I vessels' engine is an integral part. Removal or replacement is significantly more difficult,
so most repair work is done with the engine in place. Just like OBs, the SD/I application area is
divided into recreational and luxury categories.
1.2.3 PWC
According to the Personal Watercraft Industry Association (PWIA), a PWC is defined as
a "vessel with an inboard motor powering a water jet pump as its primary source of motive
power, and which is designed to be operated by a person sitting, standing, or kneeling on the
vessel."
The PWC application area is divided into the entry level, high end, and performance
categories based on the horsepower ratings of the vessel. These categories correspond to 50 to
100 hp, 100 to 175 hp, and over 175 hp accordingly. Our study considers two categories that
were available in 2002: entry level and high end. The performance category was introduced in
2003.
1.2.4 Marine SI Engines
Some OB engine manufacturers specifically build their engines to be incorporated into
boats produced by another division within the same parent company. Other manufacturers
produce and sell their engines to independent OB boat builders or consumers who need a
replacement engine. SD/I engine manufacturers typically build custom engines for SD/I boats
by marinizing automotive engines. All PWC vessel manufacturers build their own engines for
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Draft Regulatory Impact Analysis
their vessels
Marine SI engines sold today are a mix of three primary technologies: crankcase
scavenged two-stroke engines, direct-injection two-stroke engines, and four-stroke engines.
Table 6.2.2-11 in Chapter 6 presents our best estimate of the technology mix for OB and PWC
engines by power class. This technology mix is based on data submitted by manufacturers when
the certify to our existing HC+NOx exhaust emission standards. Prior to the implementation of
the existing standards, the vast majority of outboard and PWC engines were crankcase
scavenged two-stroke engines.
The following Figures show the flow of engines from the engine manufacturer to the consumer
for the different engine types.
Figure 1-2. OB Marine Economic Model Conceptual Flow Chart
Consumers
Loose Engines
Imports
• Engines
• Equipment
Consumers
New Boats
>
k.
Equipment Market
Noninteg rated
Equipment
Manufacturers
Marine SI Engine
Markets
t
k.
Merchant
Engine
Manufacturers
Integrated
Equipment
Manufacturers
Captive
Engine
Manufacturers
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Industry Characterization
Figure 1-3: PWC Economic Model Conceptual Flow Chart
Consumer
>
k
Equipment Market
>
Integrated
Manufa
i
Captive
Manufa
k
Equipment
cturers
k
Engine
cturers
Figure 1-4: Inboard Marine Economic Model Conceptual Flow Chart
Integrated
Equipment
Manufacturer
t
k
Merchant
Engine
Manufacturer
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Draft Regulatory Impact Analysis
1.3 Fuel System Components
The primary fuel system components that would be affected by the proposed rule are the
fuel tanks and fuel lines on affected equipment and vessels. This section gives an overview of
the production practices for these products.
1.3.1 Fuel Tank Production Practices
Plastic fuel tanks are either blow-molded, injection-molded, or rotational-molded.
Generally, portable, PWC, and mid-sized Small SI fuel tanks are blow-molded. Blow-molding
involves forming polyethylene in large molds using air pressure to shape the tank. Because this
has high fixed costs, blow molding is only used where production volumes are high. This works
for portable fuel tanks where the volumes are high and a single shape can be used for most
applications. For portable tanks, the fuel tank manufacturer will generally design the tank, then
send it out to a blow molder for production.
Smaller fuel tanks used in Small SI equipment are often injection-molded. In the
injection molding process, fuel tanks are formed by forcing heated plastic into molds at high
pressure. Generally, two fuel tank halves are formed, which are later fused together. This
process requires high tooling costs, but lower total fixed costs than blow-molding. Injection-
molding is typically used for smaller fuel tanks and has the advantage of giving manufacturers
the ability to work with complex tank designs.
Larger fuel tanks used on Class II equipment and in boats with installed fuel tanks are
typically rotational-molded out of cross-link polyethylene. Rotational-molding is a lower cost
alternative for smaller production volumes. In this method, a mold is filled with a powder form
of polyethylene with a catalyst material. The mold is rotated in an oven; the heat melts the
plastic and activates the catalyst which causes a strong cross-link material structure to form.
This method is used for Class II fuel tanks where the tanks are unshielded on the equipment.
These fuel tanks also used meet specific size and shape requirements for boats and are preferred
because they do not rust like metal tanks, but at the same time are more fire resistant than high-
density polyethylene fuel tanks.
Metal fuel tanks are also used on both Small SI equipment and boats. Typically, metal
tanks on Small SI equipment are made of steel. These tanks are typically stamped out in two
pieces and either welded or formed together with a seal. Aluminum fuel tanks are also used
primarily for installed marine fuel tanks because aluminum is more resistant to oxidation than
steel. In the marine industry, tank manufacturers generally custom make each tank to meet the
boat manufacturers needs. Generally, sheet aluminum is used and is cut, bent, and welded into
the required configuration.
1.3.2 Fuel Hose Production Practices
Marine hose is designed to meet the Coast Guard performance requirements as defined
by the Society of Automotive Engineer's recommended practice SAE J 1527. For fuel supply
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Industry Characterization
lines, this includes a permeation rate of 100 g/m2/day at 23°C (Class 1). For other fuel hose not
normally continuously in contact with fuel (vent and fuel fill neck), the permeation standard is
300 g/m2/day (Class 2). In general, boat builders will use Class 1 hose for both fuel supply and
vent lines for simplicity. Some boat builders use low permeation barrier hose which is well
below the permeation levels in SAE J 1527. For fuel fill necks, boat builders generally use Class
2 hose. Small SI hose is typically produced to manufacturer specifications. However,
manufacturers may specify hose based on industry standards such as those listed in SAE J30.
Most fuel supply and vent hose is extruded nitrile rubber with a coating for better wear
and flame resistance. Hose may also be reinforced with fabric or wire. (In contrast, plastic
automotive fuel lines are extruded without reinforcement and are generally referred to as
"tubing.") Hose manufacturers offer a wide variety of fuel hoses including those with a barrier
layer of low permeability material, such as nylon, THV, FKM or ethyl vinyl alcohol, either on
the inside surface or sandwiched between layers of nitrile rubber. These technologies are
discussed in more detail in Chapter 5.
Fuel fill hose used on boats is generally manufactured by hand wrapping layers of rubber
and reinforcement materials around a steel mandril. This hose is then heated to cure the rubber.
Fuel fill hose generally has a much larger diameter than fuel supply and vent hose and this
process offers an effective method of producing this larger diameter hose.
Pre-formed fuel lines are made in two ways. The first, and more common method, is to
cut lengths of extruded hose, before it is vulcanized, and slip them over a contoured mandril.
The hose is then vulcanized in the oven on the mandril to give it a preformed shape. The second
way, primarily used on handheld equipment, but also for some outboard engine fuel system
components, is to injection-mold small parts. To make the parts hollow, they are molded with a
mandril inside. To remove the mandril, the part is typically inflated with air for just long enough
to pull it off the mandril. Primer bulbs are also made in this manner.
1-7
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Draft Regulatory Impact Analysis
Chapter 1 References
1. "Industry Profile for Small Nonroad Spark-Ignition Engines and Equipment," RTI International, March 2006.
2. "Industry Profile for Marine SI Industry," RTI International, October 2006.
1-8
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Air Quality, Health, and Welfare Concerns
CHAPTER 2: Air Quality, Health, and Welfare Concerns
The proposed standards would reduce emissions of hydrocarbons (HC), oxides of
nitrogen (NOx), carbon monoxide (CO) and air toxics from the engines, vessels and equipment
subject to this proposal. These pollutants contribute to ozone, PM and CO nonattainment and to
adverse health effects associated with air toxics. The emissions from these engines, vessels and
equipment can also impact health through personal exposure and contribute to adverse
environmental effects including visibility impairment both in mandatory class I federal areas and
in areas where people live, work and recreate.
The health and environmental effects associated with emissions from Small SI engines
and equipment and Marine SI engines and vessels are a classic example of a negative externality
(an activity that imposes uncompensated costs on others). With a negative externality, a
activity's social cost (the cost on society imposed as a result of the activity taking place) exceeds
its private cost (the cost to those directly engaged in the activity). In this case, as described in
this chapter, emissions from Small SI engines and equipment and Marine SI engines and vessels
impose public health and environmental costs on society. The market system itself cannot
correct this externality. The end users of the equipment and vessels are often unaware of the
environmental impacts of their use for lawn care or recreation. Because of this, consumers fail
to send the market a signal to provide cleaner equipment and vessels. In addition, producers of
these engines, equipment, and vessels are rewarded for emphasizing other aspects of these
products (e.g., total power). To correct this market failure and reduce the negative externality, it
is necessary to give producers social cost signals. The standards EPA is proposing will
accomplish this by mandating that Small SI engines and equipment and Marine SI engines and
vessels reduce their emissions to a technologically feasible limit. In other words, with this
proposed rule the costs of the services provided by these engines and equipment will account for
social costs more fully.
In this Chapter we will discuss the impacts of the pollutants emitted by Small SI engines
and equipment and Marine SI engines and vessels on health and welfare, National Ambient Air
Quality Standard (NAAQS) attainment and personal exposure. Air quality modeling and
monitoring data presented in this chapter indicate that a large number of our citizens continue to
be affected by these emissions. Figure 2-1 illustrates the widespread nature of these problems.
Shown in this figure are counties designated as nonattainment for either or both of the 8-hour
ozone or PM2 5 NAAQS, also depicted are the mandatory class I federal areas. The emission
standards proposed in this rule would help reduce HC, NOx, air toxic and CO emissions and
their associated health and environmental effects.
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Draft Regulatory Impact Analysis
Figure 2-1: 8-Hour Ozone and PM25
Nonattainment Areas and Mandatory Class I Federal Areas
Legend
f PM and Ozone NonAttainment
^| Ozone NonAttainment
3 pm25 NonAttainment
| | Class I Areas
2.1 Ozone
In this section we review the health and welfare effects of ozone. We also describe the
air quality monitoring and modeling data which indicates that people in many areas across the
country continue to be exposed to high levels of ambient ozone and will continue to be into the
future. Emissions of volatile organic compounds (VOCs) and NOx from the engines, vessels
and equipment subject to this proposed rule contribute to these ozone concentrations.
Information on air quality was gathered from a variety of sources, including monitored ozone
concentrations, air quality modeling forecasts conducted for this rulemaking, and other state and
local air quality information.
2.1.1 Science of Ozone Formation
Ground-level ozone pollution is formed by the reaction of VOCs, of which HC are the
major subset, and NOx in the atmosphere in the presence of heat and sunlight. These pollutants,
often referred to as ozone precursors, are emitted by many types of pollution sources such as
highway and nonroad motor vehicles (including those subject to this proposed rule), power
plants, chemical plants, refineries, makers of consumer and commercial products, industrial
facilities, and smaller area sources.
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Air Quality, Health, and Welfare Concerns
The science of ozone formation, transport, and accumulation is complex.1 Ground-level
ozone is produced and destroyed in a cyclical set of chemical reactions, many of which are
sensitive to temperature and sunlight. When ambient temperatures and sunlight levels remain
high for several days and the air is relatively stagnant, ozone and its precursors can build up and
result in more ozone than typically would occur on a single high-temperature day. Ozone also
can be transported into an area from pollution sources found hundreds of miles upwind, resulting
in elevated ozone levels even in areas with low VOC or NOx emissions.
The highest levels of ozone are produced when both VOC and NOx emissions are present
in significant quantities on clear summer days. Relatively small amounts of NOx enable ozone
to form rapidly when VOC levels are relatively high, but ozone production is quickly limited by
removal of the NOx. Under these conditions NOx reductions are highly effective in reducing
ozone while VOC reductions have little effect. Such conditions are called "NOx-limited".
Because the contribution of VOC emissions from biogenic (natural) sources to local ambient
ozone concentrations can be significant, even some areas where man-made VOC emissions are
relatively low can be NOx-limited.
When NOx levels are relatively high and VOC levels relatively low, NOx forms
inorganic nitrates (i.e., particles) but relatively little ozone. Such conditions are called "VOC-
limited". Under these conditions, VOC reductions are effective in reducing ozone, but NOx
reductions can actually increase local ozone under certain circumstances. Even in VOC-limited
urban areas, NOx reductions are not expected to increase ozone levels if the NOx reductions are
sufficiently large.
Rural areas are almost always NOx-limited, due to the relatively large amounts of
biogenic VOC emissions in such areas. Urban areas can be either VOC- or NOx-limited, or a
mixture of both, in which ozone levels exhibit moderate sensitivity to changes in either pollutant.
Ozone concentrations in an area also can be lowered by the reaction of nitric oxide (NO)
with ozone, forming nitrogen dioxide (NO2); as the air moves downwind and the cycle continues,
the NO2 forms additional ozone. The importance of this reaction depends, in part, on the relative
concentrations of NOx, VOC, and ozone, all of which change with time and location.
2.1.2 Health Effects of Ozone Pollution
Exposure to ambient ozone contributes to a wide range of adverse health effects.1 These
health effects are well documented and are critically assessed in the EPA ozone air quality
criteria document (ozone AQCD) and EPA staff paper.2'3 We are relying on the data and
conclusions in the ozone AQCD and staff paper, regarding the health effects associated with
ozone exposure.
'Human exposure to ozone varies over time due to changes in ambient ozone concentration and because
people move between locations which have notable different ozone concentrations. Also, the amount of ozone
delivered to the lung is not only influenced by the ambient concentration but also by the individuals breathing route
and rate.
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Draft Regulatory Impact Analysis
Ozone-related health effects include lung function decrements, respiratory symptoms,
aggravation of asthma, increased hospital and emergency room visits, increased asthma
medication usage, inflammation of the lungs, and a variety of other respiratory effects. There is
also evidence that ozone may contribute to cardiovascular health effects. People who are more
susceptible to effects associated with exposure to ozone include children, asthmatics and the
elderly. There is also suggestive evidence that certain people may have greater genetic
susceptibility. Those with greater exposures to ozone, for instance due to time spent outdoors
(e.g., outdoor workers) are also of concern.
Based on a large number of scientific studies, EPA has identified several key health
effects associated with exposure to levels of ozone found today in many areas of the country.
Short-term (1 to 3 hours) and prolonged exposures (6 to 8 hours) to higher ambient ozone
concentrations have been linked to lung function decrements, respiratory symptoms, increased
hospital admissions and emergency room visits for respiratory problems.4'5'6'7'8'9 Repeated
exposure to ozone can increase susceptibility to respiratory infection and lung inflammation and
can aggravate preexisting respiratory diseases, such as asthma.10'Ui 12'13'14 Repeated exposure to
sufficient concentrations of ozone can also cause inflammation of the lung, impairment of lung
defense mechanisms, and possibly irreversible changes in lung structure, which over time could
lead to premature aging of the lungs and/or chronic respiratory illnesses, such as emphysema and
chronic bronchitis.15'16'17'18
Children and adults who are outdoors and active during the summer months, such as
construction workers and other outdoor workers, are among those most at risk of elevated ozone
exposures.19 Children and outdoor workers tend to have higher ozone exposures because they
typically are active outside, working, playing and exercising, during times of day and seasons
(e.g., the summer) when ozone levels are highest.20 For example, summer camp studies in the
Eastern United States and Southeastern Canada have reported significant reductions in lung
function in children who are active outdoors.21'22'23'24'25> 26'27'28 Further, children are more at risk
of experiencing health effects from ozone exposure than adults because their respiratory systems
are still developing. These individuals (as well as people with respiratory illnesses such as
asthma, especially asthmatic children) can experience reduced lung function and increased
respiratory symptoms, such as chest pain and cough, when exposed to relatively low ozone
levels during prolonged periods of moderate exertion.29'30'31'32
EPA typically quantifies ozone-related health impacts in its regulatory impact analyses
(RIAs) when possible. In the analysis of past air quality regulations, ozone-related benefits have
included morbidity endpoints and welfare effects such as damage to commercial crops. EPA has
not recently included a separate and additive mortality effect for ozone, independent of the effect
associated with fine particulate matter. For a number of reasons, including 1) advice from the
Science Advisory Board (SAB) Health and Ecological Effects Subcommittee (FLEES) that EPA
consider the plausibility and viability of including an estimate of premature mortality associated
with short-term ozone exposure in its benefits analyses and 2) conclusions regarding the
scientific support for such relationships in EPA's 2006 Air Quality Criteria for Ozone and
Related Photochemical Oxidants (the CD), EPA is in the process of determining how to
appropriately characterize ozone-related mortality benefits within the context of benefits
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Air Quality, Health, and Welfare Concerns
analyses for air quality regulations. As part of this process, we are seeking advice from the
National Academy of Sciences (NAS) regarding how the ozone-mortality literature should be
used to quantify the reduction in premature mortality due to diminished exposure to ozone, the
amount of life expectancy to be added and the monetary value of this increased life expectancy
in the context of health benefits analyses associated with regulatory assessments.
Since the NAS effort is not expected to conclude until 2008, the agency is currently
deliberating how best to characterize ozone-related mortality benefits in its rulemaking analyses
in the interim. For the analysis of the proposed small engine standards, we do not quantify an
ozone mortality benefit. So that we do not provide an incomplete picture of all of the benefits
associated with reductions in emissions of ozone precursors, we have chosen not to include an
estimate of total ozone benefits in the proposed RIA. By omitting ozone benefits in this
proposal, we acknowledge that this analysis underestimates the benefits associated with the
proposed standards. For more information regarding the quantified benefits included in this
analysis, please refer to Chapter 8.
2.1.3 Current and Projected Ozone Levels
The Clean Air Act (CAA) requires EPA to set NAAQS for wide-spread pollutants from
diverse sources considered harmful to public health and the environment. The CAA established
two types of NAAQS: primary standards to protect public health, secondary standards to protect
public welfare. The primary and secondary ozone NAAQS are identical. The 8-hour ozone
standard is met when the 3-year average of the annual 4th highest daily maximum 8-hour ozone
concentration is less than 0.08 ppm (62 FR 38855, July 18, 1997).
The proposed emission reductions from this rule would assist 8-hour ozone
nonattainment and maintenance areas in reaching the standard by each area's respective
attainment date, and maintaining the 8-hour ozone standard in the future. The emission
reductions would also help continue to lower ambient ozone levels and resulting health impacts
into the future. In this section we present information on current and projected future 8-hour
ozone levels.
2.1.3.1 Current 8-Hour Ozone Levels
A nonattainment area is defined in the CAA as an area that is violating a NAAQS or is
contributing to a nearby area that is violating the NAAQS. EPA designated nonattainment areas
for the 8-hour ozone NAAQS in June 2004. The final rule on Air Quality Designations and
Classifications for the 8-hour Ozone NAAQS (69 FR 23858, April 30, 2004) lays out the factors
that EPA considered in making the 8-hour ozone nonattainment designations, including 2001-
2003 measured data, air quality in adjacent areas, and other factors.2
2 An ozone design value is the concentration that determines whether a monitoring site meets the NAAQS
for ozone. Because of the way they are defined, design values are determined based on three consecutive-year
monitoring periods. For example, an 8-hour design value is the fourth highest daily maximum 8-hour average ozone
concentration measured over a three-year period at a given monitor. The full details of these determinations
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Draft Regulatory Impact Analysis
As of October 2006, approximately 157 million people live in the 116 areas that are
designated as nonattainment for either failing to meet the 8-hour ozone NAAQS or for
contributing to poor air quality in a nearby area.3 There are 461 full or partial counties that make
up the 116 8-hour ozone nonattainment areas, as shown in Figure 2-1.
Counties designated as ozone nonattainment were categorized, on the basis of their one-
hour ozone design value, as Subpart 1 or Subpart 2. Areas categorized as Subpart 2 were then
further classified, on the basis of their 8-hour ozone design value, as marginal, moderate, serious,
severe or extreme. The maximum attainment date assigned to an ozone nonattainment area is
based on the area's classification.
States with 8-hour ozone nonattainment areas are required to take action to bring those
areas into compliance prior to the ozone season in the attainment year. Based on the final rule
designating and classifying 8-hour ozone nonattainment areas, most 8-hour ozone nonattainment
areas will be required to attain the 8-hour ozone NAAQS in the 2007 to 2014 time frame and
then be required to maintain the 8-hour ozone NAAQS thereafter.4 The emission standards
being proposed in this action would become effective between 2008 and 2013. Thus, the
expected ozone precursor emission inventory reductions from the standards proposed in this
action would be useful to states in attaining and/or maintaining the 8-hour ozone NAAQS.
EPA's review of the ozone NAAQS is currently underway and a proposed decision in
this review is scheduled for June 2007 with a final rule scheduled for March 2008. If the ozone
NAAQS is revised then new nonattainment areas could be designated. While EPA is not relying
on it for purposes of justifying this rule, the emission reductions from this proposal would also
be helpful to states if there is an ozone NAAQS revision.
2.1.3.2 Projected 8-Hour Ozone Levels
Air quality modeling analyses completed for this proposed rule included assessing
ambient ozone concentrations with and without the proposed emission controls. The air quality
modeling predicts that without additional local, regional or national controls there will continue
(including accounting for missing values and other complexities) are given in Appendices H and I of 40 CFR Part
50. Due to the precision with which the standards are expressed (0.08 parts per million (ppm) for the 8-hour), a
violation of the 8-hour standard is defined as a design value greater than or equal to 0.085 ppm or 85 parts per billion
(ppb). For a county, the design value is the highest design value from among all the monitors with valid design
values within that county. If a county does not contain an ozone monitor, it does not have a design value. However,
readers should note that ozone design values generally represent air quality across a broad area and that absence of a
design value does not imply that the county is in compliance with the ozone NAAQS. Therefore, our analysis may
underestimate the number of counties with design values above the level of NAAQS.
3The 8-hour ozone nonattainment areas are listed in a Memo to the Docket titled "Nonattainment Areas and
Mandatory Class I Federal Areas" and contained in Docket EPA-HQ-OAR-2004-0008.
4 The Los Angeles Southcoast Air Basin 8-hour ozone nonattainment area will have to attain before June
15,2021.
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Air Quality, Health, and Welfare Concerns
to be a need for reductions in 8-hour ozone concentrations in some areas in the future.
We performed a series of ozone air quality modeling simulations for the Eastern United
States using the Comprehensive Air Quality Model with Extension (CAMx). The air quality
modeling performed for this proposed rule was based upon the same modeling system as was
used in the Clean Air Interstate rule (CAIR) and Clean Air Nonroad Diesel (CAND) legislation.
The model simulations were performed for five emission scenarios: a 2001 baseline projection, a
2020 baseline projection and a 2020 projection with controls, a 2030 baseline projection and a
2030 projection with controls.
The impacts of the proposed emission standards were determined by comparing the
model results in the future year control runs against the baseline simulations of the same year.
This modeling supports the conclusion that the proposed controls would help reduce ambient
ozone concentrations across the country.
2.1.3.2.1 Ozone Modeling Methodology
CAMx was utilized to estimate base and future-year ozone concentrations over the
Eastern United States for various emission scenarios. CAMx simulates the numerous physical
and chemical processes involved in the formation, transport, and destruction of ozone. CAMx is
a photochemical grid model that numerically simulates the effects of emissions, advection,
diffusion, chemistry, and surface removal processes on pollutant concentrations within a
three-dimensional grid. This model is commonly used in developing attainment demonstration
State Implementation Plans (SIPs) as well as estimating the ozone reductions expected to occur
from a reduction in emitted pollutants. The following sections provide an overview of the ozone
modeling completed as part of this rulemaking. More detailed information is included in the air
quality modeling technical support document (TSD), which is located in the docket for this rule.
The modeling domain used for this analysis and in the recent CAIR includes 37 states in
the Eastern U.S., see Figure 2.1-2. The Eastern modeling domain encompasses the area from the
East coast to mid-Texas and consists of two grids with differing resolutions. The model
resolution was 36 km over the outer portions of the domain and 12 km in the inner portion of the
grids. The vertical height of the eastern modeling domain is 4,000 meters above ground level
with 9 vertical layers.
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Draft Regulatory Impact Analysis
Figure 2.1-2: Map of CAIR Modeling Domain
Note: The inner area represents fine grid modeling at 12 km resolution. The outer area
represents the coarse grid modeling at 36 km resolution.
The simulation periods modeled by CAMx included several multi-day periods when
ambient measurements were representative of ozone episodes over the Eastern U. S. A
simulation period, or episode, consists of meteorological data characterized over a block of days
that are used as inputs to the air quality model. Three multi-day meteorological scenarios during
the summer of 1995 were used in the model simulations over the Eastern U.S.: June 12-24, July
5-15, and August 7-21. In general, these episodes do not represent extreme ozone events but,
instead, are generally representative of ozone levels near local design values. Each of the
emission scenarios were simulated for the selected episodes.
The meteorological data required for input into CAMx (wind, temperature, vertical
mixing, etc.) was developed by a separate meteorological model. For the Eastern U.S., the
gridded meteorological data for the three historical 1995 episodes were developed using the
Regional Atmospheric Modeling System (RAMS), version 3b. This model provided needed data
at every grid cell on an hourly basis. The meteorological modeling results were evaluated
against observed weather conditions before being input into CAMx and it was concluded that the
model fields were adequate representations of the historical meteorology. A more detailed
description of the settings and assorted input files employed in these applications is provided in
the air quality modeling TSD, which is located in the docket for this rule.
The modeling assumed background pollutant levels at the top and along the periphery of
the domain as in CAIR. Additionally, initial conditions were assumed to be relatively clean as
well. Given the ramp-up days and the expansive domains, it is expected that these assumptions
will not affect the modeling results, except in areas near the boundary (e.g., Dallas-Fort Worth
TX). The other non-emission CAMx inputs (land use, photolysis rates, etc.) were developed
using procedures employed in the highway light duty Tier 2/OTAG regional modeling. The
development of model inputs is discussed in greater detail in the air quality modeling TSD.
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Air Quality, Health, and Welfare Concerns
Future-year estimates of 8-hour ozone design values were calculated based on relative
reduction factors (RRF) between the future simulations, the 2001 base year simulation and 2001-
2003 8-hour ozone design values. The procedures for determining the RRFs are similar to those
in EPA's guidance for modeling for an 8-hour ozone standard.33 Hourly model predictions were
processed to determine daily maximum 8-hour concentrations for each grid cell for each day
modeled. The RRF for a monitoring site was determined by first calculating the multi-day mean
of the 8-hour daily maximum predictions in the nine grid cells surrounding the site using only
those predictions greater than or equal to 70 ppb, as recommended in the guidance. This
calculation was performed for the base year scenario and each of the future-year baselines. The
RRF for a site is the ratio of the mean prediction in the future-year scenario to the mean
prediction in the base year scenario. RRFs were calculated on a site-by-site basis. The future-
year design value projections were then calculated by county, based on the highest resultant
design values for a site within that county from the RRF application. For more information see
the air quality modeling TSD.
The inventories that underlie the ozone modeling conducted for this rulemaking included
emission reductions from all current or committed federal, State, and local controls including the
recent CAIR and, for the control case, including this proposed rulemaking.
Finally, it should be noted that the emission control scenarios used as input for the air
quality and benefits modeling are slightly different than the emission control program being
proposed. The proposed levels of the standards have changed, in response to new information on
the emission control technologies under consideration and other factors, since we performed the
air quality modeling for this proposed rule. Additional detail is provided in Section 3.6.
2.1.3.2.2 Areas at Risk of Future 8-Hour Ozone Violations
This section summarizes the results of recent ozone air quality modeling from the CAIR
analysis. Specifically, it provides information on our calculations of the number of people
estimated to live in counties in which ozone monitors are predicted to exceed the 8-hour ozone
NAAQS or to be within 10 percent of the 8-hour ozone NAAQS in the future.
The determination that an area is at risk of exceeding the 8-hour ozone standard in the
future was made for all areas with current design values greater than or equal to 85 ppb (or
within a 10 percent margin) and with modeling evidence that concentrations at and above this
level will persist into the future. Those interested in greater detail should review the CAIR air
quality modeling TSD.
Based upon our CAIR air quality modeling, we anticipate that without emission
reductions beyond those that were already required under promulgated regulation and approved
SIPs, ozone nonattainment will likely persist into the future. With reductions from programs
already in place (but excluding the emission reductions from this rule), the number of Eastern
counties with projected 8-hour ozone design values at or above 85 ppb in 2010 is expected to be
37 counties where 24 million people are projected to live, see Table 2.1-1. In addition, in 2010,
148 Eastern counties where 61 million people are projected to live, will be within 10 percent of
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Draft Regulatory Impact Analysis
violating the 8-hour ozone NAAQS.
Table 2.1.3.2.2-1. Eastern Counties with 2010 projected
8-hour Ozone Concentrations Above and Within 10% of the 8-hour Ozone Standard
State
Arkansas
Connecticut
Connecticut
Connecticut
Connecticut
Connecticut
Connecticut
B.C.
Delaware
Delaware
Delaware
Georgia
Georgia
Georgia
Georgia
Georgia
Georgia
Georgia
Georgia
Georgia
Illinois
Illinois
Illinois
Illinois
Indiana
Indiana
Indiana
Indiana
Indiana
Indiana
Indiana
Indiana
Indiana
Indiana
Indiana
Kentucky
Louisiana
Louisiana
Louisiana
Louisiana
Louisiana
Louisiana
Maine
Maine
Maryland
Maryland
Maryland
Maryland
Maryland
County
Crittenden Co
Fairfield Co
Hartford Co
Middlesex Co
New Haven Co
New London Co
Tolland Co
Washington Co
Kent Co
New Castle Co
Sussex Co
Bibb Co
Cobb Co
Coweta Co
De Kalb Co
Douglas Co
Fayette Co
Fulton Co
Henry Co
Rockdale Co
Cook Co
Jersey Co
Lake Co
McHenry Co
Boone Co
Clark Co
Hamilton Co
Hancock Co
La Porte Co
Lake Co
Madison Co
Marion Co
Porter Co
Shelby Co
St Joseph Co
Campbell Co
Bossier Parish
East Baton Rouge Parish
Iberville Parish
Jefferson Parish
Living_ston Parish
West Baton Rouge Parish
Hancock Co
York Co
Anne Arundel Co
Baltimore Co
Carroll Co
Cecil Co
Charles Co
2010 Projected 8-hour Ozone
Concentration (ppb)a
80.8
92.2
80.1
90.6
91.3
83.4
82.7
85
78.7
84.7
80.3
80
79.4
76.6
81.9
78.7
76.7
85.1
80.3
80.4
81.8
77
76.8
76.6
78.1
78.4
81.7
80.4
81.8
82.8
78.6
79.6
81.1
81.6
77.8
81.5
77
80.6
79.4
78.6
77.8
78.8
80.5
80.2
88.6
83.7
80
89.5
78.7
2000 pop"
50,866
882,567
857,183
155,071
824,008
259/188
136,364
572,058
126,697
500,264
156,638
153,887
607,750
89,215
665,864
92,174
91,263
816/105
119,341
7o;iTT
5,376,739
21,668
644,356
260,077
46,107
96,472
182,740
55"391
110,106
484,563
133,358
860,453
146,798
43,445
265,559
88,616
98,310
412,852
33,320
455,466
91,814
21,601
51,791
186,742
489,656
754,292
150,897
85,951
120,546
2010 popc
52,889
891,694
859,080
164,202
829,181
267,199
142,988
554,474
139,376
534,631
181,962
158,291
744,488
111,522
698,335
114,380
117,580
855,826
153,957
87,977
5,363,464
22,905
731,690
307,400
54,035
107,096
230,565
65,282
111,566
489,220
137,710
879,932
165,350
46,565
275,031
92,109
110,838
465,411
33,089
493,359
124,895
22,672
53,886
201,082
543,785
792,284
179,918
96,574
145,763
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Air Quality, Health, and Welfare Concerns
Maryland
Maryland
Maryland
Maryland
Maryland
Massachusetts
Massachusetts
Massachusetts
Massachusetts
Massachusetts
Massachusetts
Massachusetts
Michigan
Michigan
Michigan
Michigan
Michigan
Michigan
Michigan
Michigan
Michigan
Michigan
Michigan
Michigan
Michigan
Missouri
Missouri
Missouri
Missouri
Missouri
New Hampshire
New Jersey
New Jersey
New Jersey
New Jersey
New Jersey
New Jersey
New Jersey
New Jersey
New Jersey
New Jersey
New Jersey
New Jersey
New Jersey
New York
New York
New York
New York
New York
New York
New York
New York
New York
New York
New York
New York
New York
New York
Frederick Co
Harford Co
Kent Co
Montgomery Co
Prince Georges Co
Bamstable Co
Bristol Co
Essex Co
Hampden Co
Hampshire Co
Middlesex Co
Suffolk Co
Allegan Co
Benzie Co
Berrien Co
Cass Co
Genesee Co
Macomb Co
Mason Co
Muskegon Co
Oakland Co
Ottawa Co
St Clair Co
Washtenaw Co
Wayne Co
Clay Co
Jefferson Co
St Charles Co
St Louis City
St Louis Co
Hillsborough Co
Atlantic Co
Bergen Co
Camden Co
Cumberland Co
Gloucester Co
Hudson Co
Hunterdon Co
Mercer Co
Middlesex Co
Monmouth Co
Morris Co
Ocean Co
Passaic Co
Bronx Co
Chautauqua Co
Dutchess Co
Erie Co
Essex Co
Jefferson Co
Monroe Co
Niagara Co
Orange Co
Putnam Co
Queens Co
Richmond Co
Suffolk Co
Westchester Co
78.1
92.8
85.8
79.3
84.2
83.6
83
81.7
80.2
78
79.1
78.1
82.1
77.9
78.1
78.2
76.7
85.4
78.9
82
80.7
76.6
80.6
81
84.7
76.5
76.7
80.5
79.4
80.5
76.6
80.4
86
91.6
84.4
91.3
84.3
88.6
95.2
92.1
86.4
85.5
100.3
79.7
79.7
81.8
81
86.9
77.6
80.5
76.9
82.3
77.1
82.3
78.3
87.1
90.8
84.7
1952277
2182590
192197
8732341
8012515
2222230
5342678
7232419
4562228
1522251
1,465,396
6892807
1052665
152998
1622453
512104
4362141
7882149
282274
1702200
1,194,155
2382314
1642235
3222895
. 2,061,161 .
1842006
1982099
2832883
3482188
1,016,315
3802841
2522552
8842118
5082932
1462438
2542673
6082975
1212989
3502761
7502162
6152301
4702212
5102916
4892049
. 1,332,649 .
1392750
2802150
9502265
382851
111,738
7352343
2192846
3412367
952745
2,229,379
4432728
. 1,419,369 .
9232459
234,304
268,207
20,233
940,126
842,221
249,495
558,460
747,556
452,718
158,130
124862428
674,179
121,415
17,849
164,727
53,544
441,196
838,353
30,667
175,901
122992592
277,400
178,391
344,398
129642209
213,643
230,539
341,686
324,156
120242964
412,071
269,754
898,450
509,912
149,595
278,612
607,256
139,641
359,912
805,537
670,971
500,033
572,364
495,610
122982206
139,909
291,098
953,085
39,545
113,075
745,350
220,407
371,434
107,967
222392026
488,728
124722127
944,535
2-11
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Draft Regulatory Impact Analysis
North Carolina
North Carolina
North Carolina
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Oklahoma
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Rhode Island
Rhode Island
Rhode Island
South Carolina
Tennessee
Tennessee
Texas
Texas
Texas
Texas
Texas
Texas
Texas
Texas
Mecklenburg Co
Rowan Co
Wake Co
Allen Co
Ashtabula Co
Butler Co
Clermont Co
Clinton Co
Cuyaho_ga Co
Delaware Co
Franklin Co
Geauga Co
Hamilton Co
Knox Co
Lake Co
Lorain Co
Lucas Co
Medina Co
Portage Co
Summit Co
Trumbull Co
Warren Co
Wood Co
Tulsa Co
Allegheny Co
Armstrong Co
Beaver Co
Berks Co
Bucks Co
Cambria Co
Chester Co
Dauphin Co
Delaware Co
Erie Co
Franklin Co
Lancaster Co
Lehigh Co
Mercer Co
Montgomery Co
Northampton Co
Philadelphia Co
Washington Co
Westmoreland Co
York Co
Kent Co
Providence Co
Washington Co
Richland Co
Sevier Co
Shelby Co
Brazoria Co
Collin Co
Dallas Co
Denton Co
Galveston Co
Gregg Co
Harris Co
Jefferson Co
81.4
80.1
77.2
76.8
83.5
78
78
81.4
77.3
77.3
81.9
86.6
78.6
76.5
82.2
78.5
80
76.5
79.8
82.4
79.7
80
77.4
79.2
81.9
79.7
79.6
81.7
94.3
76.9
85.4
80.8
84
79.1
80.2
83.6
82.1
78.1
87.6
81.8
89.9
77.3
76.7
79.4
86.2
81.2
84.2
76.9
76.5
76.7
84.1
82.5
82.2
86.8
84.6
79.1
97.4
85
6952453
1302340
6272846
1082473
1022728
3322806
1772977
402543
1,393,977
1092989
1,068,977
902895
8452302
542500
2272511
2842664
4552053
1512095
1522061
5422898
2252116
1582383
1212065
5632299
1,28 1,665
722392
181,412
3732637
5972635
1522598
4332501
2512798
5502863
2802843
1292313
4702657
3122090
1202293
7502097
2672066
1,5 17,549
2022897
3692993
3812750
1672090
6212602
1232546
3202677
712170
8972471
2412767
4912675
2,218,899
4322976
2502158
111,379
3,400,577
2522051
814,088
143,729
787,707
106,900
104,850
384,410
205,365
47,137
123482313
136,125
121422894
102,083
843,226
59,435
237,161
292,040
447,302
173,985
162,685
552,567
226,157
186,219
129,124
610,536
122592040
72,829
183,693
388,194
648,796
146,811
478,460
265,019
543,169
284,835
135,088
513,684
323,215
122,546
772,849
279,797
124202803
205,153
372,941
404,807
174,126
621,355
137,756
349,826
96,097
958,501
281,960
677,868
223822657
554,033
283,963
121,241
327702129
260,847
2-12
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Air Quality, Health, and Welfare Concerns
Texas
Texas
Texas
Virginia
Virginia
Virginia
Virginia
Virginia
Virginia
Virginia
Virginia
Virginia
Wisconsin
Wisconsin
Wisconsin
Wisconsin
Wisconsin
Wisconsin
Wisconsin
Wisconsin
Johnson Co
Montgomery Co
Tarrant Co
Alexandria City
Arlington Co
Charles City Co
Fairfax Co
Hampton City
Hanover Co
Henrico Co
Loudoun Co
Suffolk City
Door Co
Kenosha Co
Kewaunee Co
Manitowoc Co
Milwaukee Co
Ozaukee Co
Racine Co
Sheboygan Co
Number of Violating Counties
Population of Violating Counties
Number of Counties within 10%
Population of Counties within 10%
78.2
81.2
87.2
80.9
86
77.7
85.4
78.7
80.9
78.2
78.6
77.5
82.1
91
79.9
80
82.1
85.8
83.9
87.7
37
148
126,811
2932768
. 1/46,219 .
1282283
1892453
62926
9692749
1462437
862320
2622300
1692599
632677
272961
1492577
202187
822887
9402164
822317
1882831
112,646
22,724,010
58,453,962
157,545
413,048
127102920
130,422
193,370
7_,382
120852483
153,246
98_,586
294,174
214,469
69,003
30,508
166,359
20,538
83,516
922,943
95,549
199,178
118,866
24,264,574
61,409,062
a) Bolded concentrations indicate levels above the 8-hour ozone standard.
b) Populations are based on 2000 census data.
c) Populations are based on 2000 census projections.
The CAMx model also contains a source apportionment tool which can be used to
estimate how emissions from individual source areas and regions impact modeled ozone
concentrations. Small SI and Marine SI sector contributions were calculated for the areas which
the CAIR modeling projected to have design values at or above 85 ppb in 2020. In those areas,
Small SI and Marine SI emissions were estimated to be responsible for between one and seven
percent of the ozone concentrations above 85 ppb. Additional information on the source
apportionment tool and analysis can be found in the air quality modeling TSD for this proposal.
We have described the current nonattainment with the 8-hour ozone NAAQS and that
absent additional controls, modeling predicts that there will continue to be people living in
counties with 8-hour ozone levels above the NAAQS in the future. In addition, we have
described how in the future, in areas which are projected to have ozone levels greater than 85
ppb, Small SI engines and equipment and Marine SI engines and vessels are projected to
contribute to these ozone concentrations.
These analyses demonstrate the need for reductions in emissions from this proposed rule.
As shown earlier in Figure 2-1, unhealthy ozone concentrations occur over wide geographic
areas and the engines, vessels and equipment covered in this proposed rule contribute to the
ozone precursors in and near these areas. Thus, reductions in ozone precursors from Small SI
engines and equipment and Marine SI engines and vessels are needed to assist States in attaining
and maintaining the 8-hour ozone NAAQS and reducing ozone exposures.
2-13
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Draft Regulatory Impact Analysis
2.1.3.2.3 Modeling Projections of ozone with the proposed controls
This section summarizes the results of our modeling of ozone air quality impacts in the
future due to the reductions in Small SI engine and equipment and Marine SI engine and vessel
emissions proposed in this action. Specifically, we compare baseline scenarios to scenarios with
the proposed controls. Our modeling indicates that the reductions from this proposed rule would
contribute to reducing ambient ozone concentrations and potential exposures in future years.
On a population-weighted basis, the average change in future year design values for the
eastern U.S. would be a decrease of 0.7 ppb in 2020 and 0.8 ppb in 2030. In areas with larger
design values, greater than 85 ppb, the population-weighted average decrease would be
somewhat higher, 0.8 ppb in 2020 and 1.0 ppb in 2030.
Table 2.1-2 shows the average change in future year eight-hour ozone design values.
Average changes are shown 1) for all counties with 2001-2003 8-hour ozone design values, 2)
for counties with design values that did not meet the standard in 2001-2003 ("violating"
counties), and 3) for counties that met the standard, but were within 10 percent of it in 2001-
2003. This last category is intended to reflect counties that meet the standard, but will likely
benefit from help in maintaining that status in the face of growth. The average and population-
weighted average over all counties in Table 2.1-2 demonstrates a broad improvement in ozone
air quality. The average across violating counties shows that the proposed rule would help bring
these counties into attainment. Since some of the VOC and NOx emission reductions expected
from this proposed rule would go into effect during the period when areas will need to attain the
8-hour ozone NAAQS, the projected reductions in emissions are expected to assist States and
local agencies in their effort to attain and maintain the 8-hour ozone standard. The average over
counties within ten percent of the standard shows that the proposed rule would also help those
counties to maintain the standard. All of these metrics show a decrease in 2020 and a larger
decrease in 2030, indicating in four different ways the overall improvement in ozone air quality.
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Air Quality, Health, and Welfare Concerns
Table 2.1-2: Average Change in Projected Future Year 8-hour Ozone Design Value
Average*
All
All, population-weighted
Violating counties0
Violating counties0, population-
weighted
Counties within 10 percent of the
standard"1
Counties within 10 percent of the
standard"1,
population-weighted
Number of Eastern
Counties
525
525
270
270
185
185
change in 2020 design
valueb (ppb)
-0.5
-0.7
-0.6
-0.8
-0.4
-0.5
change in 2030 design
valueb
(ppb)
-0.7
-0.8
-0.8
-1.0
-0.5
-0.7
a averages are over counties with 2001 modeled design values
b assuming the nominal modeled control scenario
0 counties whose 2001 design values exceeded the 8-hour ozone standard (>= 85 ppb)
d counties whose 2001 design values were less than but within 10 percent of the 8-hour ozone standard (between 77
and 85 ppb)
The impact of the proposed reductions has also been analyzed with respect to those areas
that have the highest projected design values. We project that there will be 13 Eastern counties
with design values at or above 85 ppb in 2030. After implementation of this proposed action, we
project that 7 of these 13 counties would be at least 40% closer to a design value of less than 85
ppb, and on average all 13 counties would be 35% closer to a design value of less than 85 ppb.
2.1.4 Environmental Effects of Ozone Pollution
There are a number of public welfare effects associated with the presence of ozone in the
ambient air.34 In this section we discuss the impact of ozone on plants, including trees,
agronomic crops and urban ornamentals.
The Air Quality Criteria Document for Ozone and related Photochemical Oxidants notes
that "ozone affects vegetation throughout the United States, impairing crops, native vegetation,
and ecosystems more than any other air pollutant".35 Like carbon dioxide (CO2) and other
gaseous substances, ozone enters plant tissues primarily through apertures (stomata) in leaves in
a process called "uptake". To a lesser extent, ozone can also diffuse directly through surface
layers to the plant's interior.36 Once sufficient levels of ozone, a highly reactive substance, (or its
reaction products) reaches the interior of plant cells, it can inhibit or damage essential cellular
components and functions, including enzyme activities, lipids, and cellular membranes,
disrupting the plant's osmotic (i.e., water) balance and energy utilization patterns.37'38 This
damage is commonly manifested as visible foliar injury such as chlorotic or necrotic spots,
2-15
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Draft Regulatory Impact Analysis
increased leaf senescence (accelerated leaf aging) and/or as reduced photosynthesis. All these
effects reduce a plant's capacity to form carbohydrates, which are the primary form of energy
used by plants.39 With fewer resources available, the plant reallocates existing resources away
from root growth and storage, above ground growth or yield, and reproductive processes, toward
leaf repair and maintenance. Studies have shown that plants stressed in these ways may exhibit a
general loss of vigor, which can lead to secondary impacts that modify plants' responses to other
environmental factors. Specifically, plants may become more sensitive to other air pollutants,
more susceptible to disease, insect attack, harsh weather (e.g., drought, frost) and other
environmental stresses. Furthermore, there is some evidence that ozone can interfere with the
formation of mycorrhiza, essential symbiotic fungi associated with the roots of most terrestrial
plants, by reducing the amount of carbon available for transfer from the host to the symbiont.40
Ozone can produce both acute and chronic injury in sensitive species depending on the
concentration level and the duration of the exposure. Ozone effects also tend to accumulate over
the growing season of the plant, so that even lower concentrations experienced for a longer
duration have the potential to create chronic stress on sensitive vegetation. Not all plants,
however, are equally sensitive to ozone. Much of the variation in sensitivity between individual
plants or whole species is related to the plant's ability to regulate the extent of gas exchange via
leaf stomata (e.g., avoidance of O3 uptake through closure of stomata).41'42'43 Other resistance
mechanisms may involve the intercellular production of detoxifying substances. Several
biochemical substances capable of detoxifying ozone have been reported to occur in plants
including the antioxidants ascorbate and glutathione. After injuries have occurred, plants may be
capable of repairing the damage to a limited extent.44 Because of the differing sensitivities
among plants to ozone, ozone pollution can also exert a selective pressure that leads to changes
in plant community composition. Given the range of plant sensitivities and the fact that
numerous other environmental factors modify plant uptake and response to ozone, it is not
possible to identify threshold values above which ozone is consistently toxic for all plants. The
next few paragraphs present additional information on ozone damage to trees, ecosystems,
agronomic crops and urban ornamentals.
Ozone also has been conclusively shown to cause discernible injury to forest trees.45'46
In terms of forest productivity and ecosystem diversity, ozone may be the pollutant with the
greatest potential for regional-scale forest impacts.47 Studies have demonstrated repeatedly that
ozone concentrations commonly observed in polluted areas can have substantial impacts on plant
function.48'49
Because plants are at the center of the food web in many ecosystems, changes to the plant
community can affect associated organisms and ecosystems (including the suitability of habitats
that support threatened or endangered species and below ground organisms living in the root
zone). Ozone impacts at the community and ecosystem level vary widely depending upon
numerous factors, including concentration and temporal variation of tropospheric ozone, species
composition, soil properties and climatic factors.50 In most instances, responses to chronic or
recurrent exposure in forest exosystems are subtle and not observable for many years. These
injuries can cause stand-level forest decline in sensitive ecosystems.51'52'53 It is not yet possible
to predict ecosystem responses to ozone with much certainty; however, considerable knowledge
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Air Quality, Health, and Welfare Concerns
of potential ecosystem responses has been acquired through long-term observations in highly
damaged forests in the United States.
Laboratory and field experiments have also shown reductions in yields for agronomic
crops exposed to ozone, including vegetables (e.g., lettuce) and field crops (e.g., cotton and
wheat). The most extensive field experiments, conducted under the National Crop Loss
Assessment Network (NCLAN) examined 15 species and numerous cultivars. The NCLAN
results show that "several economically important crop species are sensitive to ozone levels
typical of those found in the Unites States."54 In addition, economic studies have shown reduced
economic benefits as a result of predicted reductions in crop yields associated with observed
ozone levels.55'56'57
Urban ornamentals represent an additional vegetation category likely to experience some
degree of negative effects associated with exposure to ambient ozone levels and likely to impact
large economic sectors. It is estimated that more than $20 billion (1990 dollars) are spent
annually on landscaping using ornamentals, both by private property owners/tenants and by
governmental units responsible for public areas.58 This is therefore a potentially costly
environmental effect. However, in the absence of adequate exposure-response functions and
economic damage functions for the potential range of effects relevant to these types of
vegetation, no direct quantitative analysis has been conducted. Methods are not available to
allow for plausible estimates of the percentage of these expenditures that may be related to
impacts associated with ozone exposure.
2.2 Particulate Matter
In this section we review the health and welfare effects of PM. We also describe air
quality monitoring and modeling data that indicate many areas across the country continue to be
exposed to levels of ambient PM above the NAAQS. Emissions of HCs and NOx from the
engines, vessels and equipment subject to this proposed rule contribute to these PM
concentrations. Information on air quality was gathered from a variety of sources, including
monitored PM concentrations, air quality modeling done for recent EPA rulemakings and other
state and local air quality information.
2.2.1 Science of PM Formation
Particulate matter (PM) represents a broad class of chemically and physically diverse
substances. It can be principally characterized as discrete particles that exist in the condensed
(liquid or solid) phase spanning several orders of magnitude in size. PM is further described by
breaking it down into size fractions. PM10 refers to particles generally less than or equal to 10
micrometers (|im) in diameter. PM2 5 refers to fine particles, those particles generally less than
or equal to 2.5 jim in diameter. Inhalable (or "thoracic") coarse particles refer to those particles
generally greater than 2.5 jim but less than or equal to 10 jim in diameter. Ultrafine PM refers to
particles with diameters generally less than 100 nanometers (0.1 jim). Larger particles (>10 |im)
tend to be removed by the respiratory clearance mechanisms, whereas smaller particles are
deposited deeper in the lungs.
2-17
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Draft Regulatory Impact Analysis
Fine particles are produced primarily by combustion processes and by transformations of
gaseous emissions (e.g., SOx, NOx and VOCs) in the atmosphere. The chemical and physical
properties of PM2 5 may vary greatly with time, region, meteorology and source category. Thus,
PM2 5, may include a complex mixture of different pollutants including sulfates, nitrates, organic
compounds, elemental carbon and metal compounds. These particles can remain in the
atmosphere for days to weeks and travel through the atmosphere hundreds to thousands of
kilometers.
The engines, vessels and equipment that would be covered by the proposed standards
contribute to ambient PM levels through primary (direct) and secondary (indirect) PM. Primary
PM is directly emitted into the air, and secondary PM forms in the atmosphere from gases
emitted by fuel combustion and other sources. Along with primary PM, the engines, vessels and
equipment controlled in this action emit HC and NOx, which react in the atmosphere to form
secondary PM25. Both types of directly and indirectly formed particles from Small SI engines
and equipment and Marine SI engines and vessels are found principally in the fine fraction.
EPA has recently amended the PM NAAQS (71 FR 61144, October 17, 2006). The final
rule, signed on September 21, 2006 and published on October 17, 2006, addressed revisions to
the primary and secondary NAAQS for PM to provide increased protection of public health and
welfare, respectively. The primary PM2 5 NAAQS include a short-term (24-hour) and a
long-term (annual) standard. The level of the 24-hour PM25 NAAQS has been revised from 65
|ig/m3 to 35 |ig/m3 to provide increased protection against health effects associated with
short-term exposures to fine particles. The current form of the 24-hour PM2 5 standard was
retained (e.g., based on the 98th percentile concentration averaged over three years). The level
of the annual PM25 NAAQS was retained at 15 |ig/m3, continuing protection against health
effects associated with long-term exposures. The current form of the annual PM2 5 standard was
retained as an annual arithmetic mean averaged over three years, however, the following two
aspects of the spatial averaging criteria were narrowed: (1) the annual mean concentration at
each site shall be within 10 percent of the spatially averaged annual mean, and (2) the daily
values for each monitoring site pair shall yield a correlation coefficient of at least 0.9 for each
calendar quarter. With regard to the primary PM10 standards, the 24-hour PM10 NAAQS was
retained at a level of 150 |ig/m3 not to be exceeded more than once per year on average over a
three-year period. Given that the available evidence does not suggest an association between
long-term exposure to coarse particles at current ambient levels and health effects, EPA has
revoked the annual PM10 standard.
With regard to the secondary PM standards, EPA has revised these standards to be
identical in all respects to the revised primary standards. Specifically, EPA has revised the
current 24-hour PM2 5 secondary standard by making it identical to the revised 24-hour PM2 5
primary standard, retained the annual PM2 5 and 24-hour PM10 secondary standards, and revoked
the annual PM10 secondary standards. This suite of secondary PM standards is intended to
provide protection against PM-related public welfare effects, including visibility impairment,
effects on vegetation and ecosystems, and material damage and soiling.
2-18
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Air Quality, Health, and Welfare Concerns
2.2.2 Health Effects of PM
As stated in the EPA Particulate Matter Air Quality Criteria Document (PM AQCD),
available scientific findings "demonstrate well that human health outcomes are associated with
ambient PM."5 We are relying primarily on the data and conclusions in the PM AQCD and PM
staff paper, which reflects EPA's analysis of policy-relevant science from the PM AQCD,
regarding the health effects associated with particulate matter.59'60 We also present additional
recent studies published after the cut-off date for the PM AQCD.6'61 Taken together this
information supports the conclusion that PM-related emissions from Small SI engines and
equipment and Marine SI engines and vessels are associated with adverse health effects.
2.2.2.1 Short-term Exposure Mortality and Morbidity Studies
As discussed in the PM AQCD, short-term exposure to PM2 5 is associated with mortality
from cardiopulmonary diseases (PM AQCD, p. 8-305), hospitalization and emergency
department visits for cardiopulmonary diseases (PM AQCD, p. 9-93), increased respiratory
symptoms (PM AQCD, p. 9-46), decreased lung function (PM AQCD Table 8-34) and
physiological changes or biomarkers for cardiac changes (PM AQCD, Section 8.3.1.3.4). In
addition, the PM AQCD describes a limited body of new evidence from epidemiologic studies
for potential relationships between short-term exposure to PM and health endpoints such as low
birth weight, preterm birth, and neonatal and infant mortality. (PM AQCD, Section 8.3.4).
Among the studies of effects from short-term exposure to PM2 5, several studies
specifically address the contribution of mobile sources to short-term PM2 5 effects on daily
mortality. These studies indicate that there are statistically significant associations between
mortality and PM related to mobile source emissions (PM AQCD, p. 8-85). The analyses
incorporate source apportionment tools into daily mortality studies and are briefly mentioned
here. Analyses incorporating source apportionment by factor analysis with daily time-series
studies of daily death established a specific influence of mobile source-related PM25 on daily
mortality62 and a concentration-response function for mobile source-associated PM2 5 and daily
mortality.63 Another recent study in 14 U.S. cities examined the effect of PM10 exposures on
daily hospital admissions for cardiovascular disease. They found that the effect of PM10 was
significantly greater in areas with a larger proportion of PM10 coming from motor vehicles,
indicating that PM10 from these sources may have a greater effect on the toxicity of ambient
5 Personal exposure includes contributions from many different types of particles, from many sources, and
in many different environments. Total personal exposure to PM includes both ambient and nonambient components;
and both components may contribute to adverse health effects.
"These additional studies are included in the 2006 Provisional Assessment of Recent Studies on Health
Effects of Particulate Matter Exposure. The provisional assessment did not and could not (given a very short
timeframe) undergo the extensive critical review by EPA, CASAC, and the public, as did the PM AQCD. The
provisional assessment found that the "new" studies expand the scientific information and provide important insights
on the relationship between PM exposure and health effects of PM. The provisional assessment also found that
"new" studies generally strengthen the evidence that acute and chronic exposure to fine particles and acute exposure
to thoracic coarse particles are associated with health effects.
2-19
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Draft Regulatory Impact Analysis
PM10 when compared with other sources.64 These studies provide evidence that PM-related
emissions, specifically from mobile sources, are associated with adverse health effects.
2.2.2.2 Long-term Exposure Mortality and Morbidity Studies
Long-term exposure to elevated ambient PM2 5 is associated with mortality from
cardiopulmonary diseases and lung cancer (PM AQCD, p. 8-307), and effects on the respiratory
system such as decreased lung function or the development of chronic respiratory disease (PM
AQCD, pp. 8-313, 8-314). Of specific importance to this proposal, the PM AQCD also notes
that the PM components of gasoline and diesel engine exhaust represent one class of
hypothesized likely important contributors to the observed ambient PM-related increases in lung
cancer incidence and mortality (PM AQCD, p. 8-318).
The PM AQCD and PM Staff Paper emphasize the results of two long-term studies, the
Six Cities and American Cancer Society (ACS) prospective cohort studies, based on several
factors - the inclusion of measured PM data, the fact that the study populations were similar to
the general population, and the fact that these studies have undergone extensive reanalysis (PM
AQCD, p. 8-306, Staff Paper, p.3-18).65'66'67 These studies indicate that there are significant
associations for all-cause, cardiopulmonary, and lung cancer mortality with long-term exposure
to PM2 5. A variety of studies have been published since the completion of the PM AQCD. One
such study, an analysis of a subset of the ACS cohort data, which was published after the PM
AQCD was finalized but in time for the 2006 Provisional Assessment, found a larger association
than had previously been reported between long-term PM2 5 exposure and mortality in the Los
Angeles area using a new exposure estimation method that accounted for variations in
concentration within the city.68 EPA is assessing the significance of this study within the context
of the broader literature.
As discussed in the PM AQCD, the morbidity studies that combine the features of cross-
sectional and cohort studies provide the best evidence for chronic exposure effects. Long-term
studies evaluating the effect of ambient PM on children's development have shown some
evidence indicating effects of PM25 and/or PM10 on reduced lung function growth (PM AQCD,
Section 8.3.3.2.3). One such study, which was summarized in the 2006 Provisional Assessment,
reported the results of a cross-sectional study of outdoor PM2 5 and measures of atherosclerosis in
the Los Angeles basin.69 The study found significant associations between ambient residential
PM25 and carotid intima-media thickness (CEVIT), an indicator of subclinical atherosclerosis, an
underlying factor in cardiovascular disease. EPA is assessing the significance of this study
within the context of the broader literature.
2.2.2.3 Roadway-Related Exposure and Health Studies
A recent body of studies reinforces the findings of these PM morbidity and mortality
effects by looking at traffic-related exposures, PM measured along roadways, or time spent in
traffic and adverse health effects. While many of these studies did not measure PM specifically,
they include potential exhaust exposures which include mobile source PM because they employ
indices such as roadway proximity or traffic volumes. One study with specific relevance to
2-20
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Air Quality, Health, and Welfare Concerns
PM2 5 health effects is a study that was done in North Carolina looking at concentrations of PM25
inside police cars and corresponding physiological changes in the police personnel driving the
cars. The authors report significant elevations in markers of cardiac risk associated with
concentrations of PM25 inside police cars on North Carolina state highways.70 A number of
studies of traffic-related pollution have shown associations between fine particles and adverse
respiratory outcomes in children who live near major roadways. 71>72'73 Additional information
on near-roadway health effects is included in the recent Mobile Source Air Toxics rule (72 FR
8428, February 26, 2007).
2.2.3 Current and Projected PM Levels
The proposed emission reductions from this rule would assist PM nonattainment areas in
reaching the standard by each area's respective attainment date and assist PM maintenance areas
in maintaining the PM standards in the future. The emission reductions would also help continue
to lower ambient PM levels and resulting health impacts into the future. In this section we
present information on current and future attainment of the PM standards.
2.2.3.1 Current PM2 5 Levels
A nonattainment area is defined in the Clean Air Act (CAA) as an area that is violating
an ambient standard or is contributing to a nearby area that is violating the standard. In 2005,
EPA designated 39 nonattainment areas for the 1997 PM25 NAAQS based on air quality design
values (using 2001-2003 or 2002-2004 measurements) and a number of other factors.7(70 FR
943, January 5, 2005; 70 FR 19844, April 14, 2005) These areas are comprised of 208 full or
partial counties with a total population exceeding 88 million.8 As mentioned in Section 2.2.1,
the 1997 PM25 NAAQS were recently revised and the 2006 PM2 5 NAAQS became effective on
December 18, 2006. Nonattainment areas will be designated with respect to the new 2006 PM
NAAQS in early 2010. Table 2.2-1 presents the number of counties in areas currently
designated as nonattainment for the 1997 PM25 NAAQS as well as the number of additional
counties which have monitored data that is violating the 2006 PM2 5 NAAQS.
7 The full details involved in calculating a PM2 5 design value are given in Appendix N of 40 CFR Part 50.
8The PM2 5 nonattainment areas are listed in a Memo to the Docket titled "Nonattainment Areas and
Mandatory Class I Federal Areas" and contained in Docket EPA-HQ-OAR-2004-0008.
2-21
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Draft Regulatory Impact Analysis
Table 2.2-1. Fine Particle Standards: Current
Nonattainment Areas and Other Violating Counties
1997 PM2, Standards:
2006 PM2, Standards:
39 areas currently designated
Counties with violating monitors2
Total
Number of
Cniintips
208
49
257
Population1
88,394,000
18,198,676
106,592,676
1 Population numbers are from 2000 census data.
2 This table provides an estimate of the counties violating the 2006 PM25 NAAQS based on 2003-05 air quality data.
The areas designated as nonattainment for the 2006 PM2 5 NAAQS will be based on 3 years of air quality data from
later years. Also, the county numbers in the summary table includes only the counties with monitors violating the
2006 PM2 5 NAAQS. The monitored county violations may be an underestimate of the number of counties and
populations that will eventually be included in areas with multiple counties designated nonattainment.
States with PM2 5 nonattainment areas will be required to take action to bring those areas
into compliance in the future. Most PM25 nonattainment areas will be required to attain the 1997
PM25 NAAQS in the 2010 to 2015 time frame and then be required to maintain the 1997 PM25
NAAQS thereafter.9 The attainment dates associated with the potential nonattainment areas
based on the 2006 PM25 NAAQS would likely be in the 2015 to 2020 timeframe. The emission
standards being proposed in this action would become effective between 2008 and 2013. The
expected PM2 5 inventory reductions from the standards proposed in this action would be useful
to states in attaining or maintaining the PM25 NAAQS.
2.2.3.2 Current PM10 Levels
EPA designated PM10 nonattainment areas in 1990.10 As of October 2006, approximately
28 million people live in the 46 areas that are designated as PM10 nonattainment, for either
failing to meet the PM10 NAAQS or for contributing to poor air quality in a nearby area. There
are 46 full or partial counties that make up the PM10 nonattainment areas.11
9The EPA finalized PM2 5 attainment and nonattainment areas in April 2005. The EPA finalized the PM
Implementation rule in March 2007.
10A PM10 design value is the concentration that determines whether a monitoring site meets the NAAQS for
PM10. The full details involved in calculating a PM10 design value are given in Appendices H and I of 40 CFR Part
50.
"The PM10 nonattainment areas are listed in a Memo to the Docket titled "Nonattainment Areas and
Mandatory Class I Federal Areas" and contained in Docket EPA-HQ-OAR-2004-0008.
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Air Quality, Health, and Welfare Concerns
2.2.3.3 Projected PM2 5 Levels
Recent air quality modeling predicts that without additional controls there will continue
to be a need for reductions in PM concentrations in the future. In the following sections we
describe the recent PM air quality modeling and results of the modeling.
2.2.3.3.1 PM Modeling Methodology
Recently PM air quality analyses were performed for the PM NAAQS final rule, which
was promulgated by EPA in 2006. The Community Multiscale Air Quality (CMAQ) model was
used as the tool for simulating base and future year concentrations of PM, visibility and
deposition in support of the PM NAAQS air quality assessments. The PM NAAQS analysis
included all federal rules up to and including the Clean Air Interstate Rule (CAIR) and all final
mobile source rule controls as of October 2006. Details on the PM air quality modeling are
provided in the RIA for the final PM NAAQS rule, included in the docket for this proposed rule.
2.2.3.3.2 Areas at Risk of Future PM25 Violations
Air quality modeling performed for the final PM NAAQS indicates that in the absence of
additional local, regional or national controls, there will likely continue to be counties that will
not attain some combination of the annual 2006 PM25 standard (15 |ig/m3) and the daily 2006
PM2 5 standard (35 |ig/m3). The PM NAAQS analysis provides estimates of future PM25 levels
across the country. For example, in 2015 based on emission controls currently adopted or
expected to be in place12, we project that 53 million people will live in 52 counties with projected
PM2 5 design values at and above the 2006 standard, see Table 2.2-2.13 The proposed rule would
provide emission reductions that will help areas to attain the PM2 5 NAAQS. Table 2.2-2 also
lists the 54 counties, where 27 million people are projected to live, with 2015 projected design
values that do not violate the PM2 5 NAAQS but are within ten percent of it. The proposed rule
may help ensure that these counties continue to maintain their attainment status.
Table 2.2-2 Counties with 2015 Projected PM25 Design Values
Above and within 10% of the 2006 PM25 Standard
State
Alabama
California
California
County
Jefferson Co
Alameda Co
Butte Co
2015 Projected
Annual PM2 5 Design
Value (ug/m3)a
15.9
13.3
13.4
2015 Projected Daily
PM2 5 Design Value
(ug/m3)a
36.9
59.4
50.7
2015 Population"
669,850
1,628,698
242,166
12Counties forecast to remain in nonattainment may need to adopt additional local or regional controls to
attain the standards by dates set pursuant to the Clean Air Act. The emissions reductions associated with this
proposed rule would help these areas attain the PM standards by their statutory date.
13Note that this analysis identifies only counties projected to have a violating monitor; the number of
counties to be designated and the associated population would likely exceed these estimates.
2-23
-------
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
California
Connecticut
Georgia
Georgia
Georgia
Georgia
Georgia
Georgia
Georgia
Idaho
Idaho
Idaho
Idaho
Idaho
Illinois
Illinois
Illinois
Illinois
Indiana
Indiana
Indiana
Kentucky
Maryland
Maryland
Maryland
Massachusetts
Michigan
Michigan
Colusa Co
Contra Costa Co
Fresno Co
Imperial Co
Inyo Co
KemCo
Kings Co
Los Angeles Co
Merced Co
Orange Co
Placer Co
Riverside Co
Sacramento Co
San Bernardino Co
San Diego Co
San Francisco Co
San Joaquin Co
San Luis Obispo Co
San Mateo Co
Santa Clara Co
Solano Co
Sonoma Co
Stanislaus Co
Sutler Co
Tulare Co
Ventura Co
Yolo Co
Fairfield Co
Bibb Co
Clayton Co
DeKalb Co
Floyd Co
Fulton Co
Muscogee Co
Wilkinson Co
Ada Co
Bannock Co
Canyon Co
Power Co
Shoshone Co
Cook Co
Madison Co
St. Clair Co
Will Co
Clark Co
Lake Co
Marion Co
Jefferson Co
Anne Arundel Co
Baltimore city
Baltimore Co
Hampden Co
Kalamazoo Co
Kent Co
9.5
12.6
20.1
14.8
6.'l
21.3
17.2
23.7
15.8
20.0
11.4
27.8
i2.2
24,6
15.8
11.3
15.4
9.4
10.5
10.7
11.7
10.0
16.6
il.2
21.2
14.1
10.2
11.0
13.7
13.9
13.6
14.0
15.5
13.4
13.6
8.9
9.1
9.2
10.5
i'2.4
15.5
15.2
14.6
13.2
13.6
13.4
13.5
13.8
11.1
13.0
11.3
11.6
12.8
12.0
33.5
61.3
73.0
45.7
38.'l
81.4
70.6
62.2
54.4
41.1
38.1
73.5
49.8
65.7
40.7
52.5
51.1
35.8
41.9
48.5
57.7
38.9
61.9
^3
77.2
38.8
33.0
31.6
27"0
28.7
3L5
30.9
32.2
34.2
29.3
32.2
40.2
32.6
36.6
36.2
37.1
35.5
30.4
32.0
3U
40.8
33!
331
33.2
35.5
32.6
32.9
32.7
31.9
23,066
1,155,323
960,934
173,482
19,349
804,940
161,607
9,910,805
250,152
3,467,120
403,624
2,015,955
1,488,456
2,157,926
3,489,368
765^846
675,362
304J379
785,949
1,899,727
529,784
569,486
547,041
99,716
441,185
923,205
206,388
893,629
160,468
280,476
715,947
97,674
877,365
197,634
11,259
397,456
88,033
154,137
8,932
15,646
5,362,931
271,854
251,612
634,068
112,523
490,795
889,645
710,231
57.1322
596,076
810,172
452J355
257,817
654,449
-------
Michigan
Michigan
Michigan
Montana
Montana
New Jersey
New Jersey
New Jersey
New York
New York
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Ohio
Oregon
Oregon
Oregon
Oregon
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Tennessee
Utah
Utah
Utah
Utah
Utah
Washington
Washington
Washington
Washington
Washington
Washington
West Virginia
West Virginia
West Virginia
Wisconsin
Wisconsin
Wyoming
Oakland Co
St. Clair Co
Wayne Co
Lincoln Co
Missoula Co
Camden Co
Hudson Co
Union Co
Bronx Co
New York Co
Cuyahoga Co
Franklin Co
Hamilton Co
Jefferson Co
Lucas Co
Scioto Co
Trumbull Co
Jackson Co
Klamath Co
Lane Co
Washington Co
Allegheny Co
Beaver Co
Berks Co
Dauphin Co
Lancaster Co
Lehigh Co
Mercer Co
Northampton Co
Philadelphia Co
York Co
KnoxCo
Box Elder Co
Cache Co
Salt Lake Co
Utah Co
Weber Co
Clark Co
King Co
Pierce Co
Snohomish Co
Thurston Co
Yakima Co
Berkeley Co
Hancock Co
Kanawha Co
Milwaukee Co
Waukesha Co
Sheridan Co
Number of Violating Counties
Population of Violating Counties
Number of Counties within 10%
Population of Counties within 10%
13.0
12.5
17.4
is.o
10.6
11.1
12.0
12.2
12.8
14.0
15.4
13.7
14.3
14.2
12.5
15.6
iTi
10.9
10.1
i2.9
9.0
16.5
12.1
12.0
11.0
12.2
10.5
11.0
10.9
13.3
12.3
13.6
8.6
12.5
12.6
9.3
9.1
9.2
10.8
11.1
11.3
8.9
9.6
12.0
13.4
13.9
12.1
11.8
10.5
33.2
32.5
39.0
"42.4
32.1
32.1
32.8
32.8
m
33.2
40.0
33"5
34.2
34.2
32.2
34.3
34.2
37.6
39.1
53.6
32.0
53.4
33.2
35.5
33.3
33.7
34.7
31.6
35.0
35.2
35.9
29.6
39.0
51.9
49.3
36.7
36.2
34.3
34.0
43.0
40.1
34.9
T4.9
32.7
32.7
28.9
32.1
32.4
31.8
52
54
1,355,670
185,970
1,921,253
19,875
118,303
512,135
604,036
525,096
1,283,316
1,551,641
1,325,507
1,181,578
841,858
68,909
443,230
81,013
227,546
250,169
69,423
387,237
639,839
1,245,917
184,648
396,410
272,748
535,622
328,523
123,577
286,838
1,372,037
417,408
448,931
49,878
114,729
1,133,410
508,106
229,807
479,002
2,013,808
879,363
782,319
264,364
261,452
99^349
30,857
1 96,498
908,336
441,482
28,623
53,468,515
26,896,926
a Bolded concentrations indicate levels above the annual PM2 5 standard.
b Populations are based on 2000 census projections.
-------
Draft Regulatory Impact Analysis
2.2.4 Environmental Effects of PM Pollution
In this section we discuss some of the public welfare effects of PM and its precursors,
including NOx, such as visibility impairment, acid deposition, eutrophication, nitrification and
fertilization, materials damage, and deposition of PM.
2.2.4.1 Visibility Impairment
Visibility can be defined as the degree to which the atmosphere is transparent to visible
light.74 Visibility impairment manifests in two principal ways: as local visibility impairment
and as regional haze.75 Local visibility impairment may take the form of a localized plume, a
band or layer of discoloration appearing well above the terrain as a result from complex local
meteorological conditions. Alternatively, local visibility impairment may manifest as an urban
haze, sometimes referred to as a "brown cloud." This urban haze is largely caused by emissions
from multiple sources in the urban areas and is not typically attributable to only one nearby
source or to long-range transport. The second type of visibility impairment, regional haze,
usually results from multiple pollution sources spread over a large geographic region. Regional
haze can impair visibility over large regions and across states.
Visibility is important because it directly affects people's enjoyment of daily activities in
all parts of the country. Individuals value good visibility for the well-being it provides them
directly, both in where they live and work, and in places where they enjoy recreational
opportunities. Visibility is also highly valued in significant natural areas such as national parks
and wilderness areas, and special emphasis is given to protecting visibility in these areas. For
more information on visibility see the 2004 PM AQCD as well as the 2005 PM Staff Paper.76'77
Fine particles are the major cause of reduced visibility in parts of the United States. To
address the welfare effects of PM on visibility, EPA set secondary PM2 5 standards which would
act in conjunction with the establishment of a regional haze program. In setting this secondary
standard, EPA concluded that PM2 5 causes adverse effects on visibility in various locations,
depending on PM concentrations and factors such as chemical composition and average relative
humidity. The secondary (welfare-based) PM2 5 NAAQS was established as equal to the suite of
primary (health-based) NAAQS. Furthermore, section 169 of the Act provides additional
authority to remedy existing visibility impairment and prevent future visibility impairment in the
156 national parks, forests and wilderness areas labeled as mandatory class I federal areas (62
FR 38680-81, July 18, 1997).1415 In July 1999 the regional haze rule (64 FR 35714) was put in
place to protect the visibility in mandatory class I federal areas. Visibility can be said to be
14 These areas are defined in section 162 of the Act as those national parks exceeding 6,000 acres ,
wilderness areas and memorial parks exceeding 5,000 acres, and all international parks which were in existence on
August 7, 1977.
15The mandatory class I federal areas are listed in a Memo to the Docket titled "Nonattainment Areas and
Mandatory Class I Federal Areas" and contained in Docket EPA-HQ-OAR-2004-0008.
2-26
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Air Quality, Health, and Welfare Concerns
impaired in both PM2 5 nonattainment areas and mandatory class I federal areas.
EPA has determined that emissions from nonroad engines significantly contribute to air
pollution that may be reasonably anticipated to endanger public health and welfare for visibility
effects in particular (67 FR 68242, November 8, 2002). The hydrocarbon emissions from the
Small SI engines and equipment subject to this proposed rule are PM-precursors and contribute
to these visibility effects. This is evident in the PM and visibility modeling recently completed
for the PM NAAQS and the CAIR. Small SI engines and equipment and Marine SI engines and
vessels were included in the PM NAAQS and CAIR PM and visibility modeling which projected
visibility problems persisting in the future.78'79 In this section we present current information and
projected estimates about both visibility impairment related to ambient PM2 5 levels across the
country and visibility impairment in mandatory class I federal areas. We conclude that visibility
will continue to be impaired in the future and the projected emission reductions from this
proposed action would help improve visibility conditions across the country and in mandatory
class I federal areas.
2.2.4.1.1 Current Visibility Impairment
The need for reductions in the levels of PM2 5 is widespread. Currently, high ambient
PM2 5 levels are measured throughout the country. Fine particles may remain suspended for days
or weeks and travel hundreds to thousands of kilometers, and thus fine particles emitted or
created in one county may contribute to ambient concentrations in a neighboring region.80
As mentioned above, the secondary PM2 5 standards were set as equal to the suite of
primary PM2 5 standards. Recently designated PM2 5 nonattainment areas indicate that, as of
October 2006, almost 90 million people live in 208 counties that are in nonattainment for the
PM2 5 NAAQS. Thus, at least these populations (plus others who travel to these areas) would
likely be experiencing visibility impairment. Emissions of PM precursors, such as
hydrocarbons, from Small SI engines and equipment and Marine SI engines and vessels
contribute to this impairment.
2.2.4.1.2 Current Visibility Impairment at Mandatory Class I Federal Areas
Detailed information about current and historical visibility conditions in mandatory class
I federal areas is summarized in the EPA Report to Congress and the 2002 EPA Trends
Report.81'82 The conclusions draw upon the Interagency Monitoring of Protected Visual
Environments (IMPROVE) network data. One of the objectives of the IMPROVE monitoring
network program is to provide regional haze monitoring representing all mandatory class I
federal areas where practical. The National Park Service report also describes the state of
national park visibility conditions and discusses the need for improvement.83
The regional haze rule requires states to establish goals for each affected mandatory class
I federal area to improve visibility on the haziest days (20% most impaired days) and ensure no
degradation occurs on the cleanest days (20% least impaired days). Although there have been
general trends toward improved visibility, progress is still needed on the haziest days.
2-27
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Draft Regulatory Impact Analysis
Specifically, as discussed in the 2002 EPA Trends Report,without the effects of pollution a
natural visual range in the United States is approximately 75 to 150 km in the East and 200 to
300 km in the West. In 2001, the mean visual range for the worst days was 29 km in the East
and 98 km in the West.84
2.2.4.1.3 Future Visibility Impairment
Recent modeling for the final PM NAAQS rule was used to project PM2 5 levels in the
U.S. in 2015. The results suggest that PM25 levels above the 2006 NAAQS will persist in the
future. We predicted that in 2015, there will be 52 counties with a population of 53 million
where PM2 5 levels will exceed the 2006 PM2 5 NAAQS. Thus, in the future, a percentage of the
population may continue to experience visibility impairment in areas where they live, work and
recreate.
The emissions from Small SI engines and equipment and Marine SI engines and vessels
contribute to visibility impairment. These emissions occur in and around areas with PM25 levels
above the PM2 5 NAAQS. Thus, the emissions from these sources contribute to the current and
anticipated visibility impairment and the proposed emission reductions would help improve
future visibility impairment.
2.2.4.1.4 Future Visibility Impairment at Mandatory Class I Federal Areas
Achieving the PM2 5 NAAQS will help improve visibility across the country, but it will
not be sufficient to meet the statutory goal of no manmade impairment in the mandatory class I
federal areas (64 FR 35722, July 1, 1999 and 62 FR 38680, July 18, 1997). In setting the
NAAQS, EPA discussed how the NAAQS in combination with the regional haze program, is
deemed to improve visibility consistent with the goals of the Act.85 In the East, there are and
will continue to be areas with PM2 5 concentrations above the PM2 5 NAAQS and where light
extinction is significantly above natural background. Thus, large areas of the Eastern United
States have air pollution that is causing and will continue to cause visibility problems. In the
West, scenic vistas are especially important to public welfare. Although the PM2 5 NAAQS is
met in most areas outside of California, virtually the entire West is in close proximity to a scenic
mandatory class I federal area protected by 169 A and 169B of the CAA.
Recent modeling for the CAIR was used to project visibility conditions in mandatory
class I federal areas across the country in 2015. The results for the mandatory class I federal
areas suggest that these areas are predicted to continue to have visibility impairment above
background on the 20% worst days in the future.
The overall goal of the regional haze program is to prevent future visibility impairment
and remedy existing visibility impairment in mandatory class I federal areas. As shown by the
future visibility estimates in Table 2.2-3, it is projected that there will continue to be mandatory
class I federal areas with visibility levels above background in 2015. Additional emission
reductions will be needed from the broad set of sources that contribute, including the engines,
vessels and equipment subject to this proposed rule.86 The reductions proposed in this action are
2-28
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Air Quality, Health, and Welfare Concerns
a part of the overall strategy to achieve the visibility goals of the Act and the regional haze
program.
Table 2.2-3: Current (1998
Background Levels
-2002) Visibility, Projected (2015) Visibility, and Natural
for the 20% Worst Days at 116 IMPROVE Sites
Class I Area Name3
Acadia
Agua Tibia
Alpine Lakes
Anaconda - Pintler
Arches
Badlands
Bandelier
Big Bend
Black Canyon of the Gunnison
Bob Marshall
Boundary Waters Canoe Area
Bridger
Brigantine
Bryce Canyon
Cabinet Mountains
Caney Creek
Canyonlands
Cape Romain
Caribou
Carlsbad Caverns
Chassahowitzka
Chiricahua NM
Chiricahua W
Craters of the Moon
Desolation
Dolly Sods
Dome Land
Eagle Cap
Eagles Nest
Emigrant
Everglades
Fitzpatrick
Flat Tops
Galiuro
Gates of the Mountains
Gila
Glacier
Glacier Peak
Grand Teton
Great Gulf
Great Sand Dunes
Great Smoky Mountains
Guadalupe Mountains
Hells Canyon
Isle Royale
James River Face
State
ME
CA
WA
MT
UT
SD
NM
TX
CO
MT
MN
WY
NJ
UT
MT
AR
UT
SC
CA
NM
FL
AZ
AZ
ID
CA
WV
CA
OR
CO
CA
FL
WY
CO
AZ
MT
NM
MT
WA
WY
NH
CO
TN
TX
OR
MI
VA
1998-2002 Baseline
Visibility (deciviews)b
22.7
23.2
18.0
12.3
12.0
17.3
13.2
18.4
11.6
14.2
20.0
11.5
27.6
12.0
13.8
25.9
12.0
25.9
14.8
17.6
25.7
13.9
13.9
14.7
12.9
27.6
20.3
19.6
11.3
17.6
20.3
11.5
11.3
13.9
11.2
13.5
19.5
14.0
12.1
23.2
13.1
29.5
17.6
18.1
21.1
28.5
201 5 CAIR Control Case
Visibility0 (deciviews)
21.0
23.2
17.4
12.2
12.1
16.8
13.2
18.3
11.4
14.0
19.0
11.3
25.4
11.9
13.4
24.1
12.0
23.9
14.6
17.9
23.0
13.9
13.9
14.7
12.8
23.9
19.9
19.0
11.4
17.4
19.2
11.3
11.4
14.1
10.8
13.5
19.1
13.8
12.0
21.2
13.0
26.1
17.5
18.0
20.1
25.1
Natural Background
(deciviews)
11.5
7.2
7.9
7.3
7.0
7.3
7.0
6.9
7.1
7.4
11.2
7.1
11.3
7.0
7.4
11.3
7.0
11.4
7.3
7.0
11.5
6.9
6.9
7.1
7.1
11.3
7.1
7.3
7.1
7.1
11.2
7.1
7.1
6.9
7.2
7.0
7.6
7.8
7.1
11.3
7.1
11.4
7.0
7.3
11.2
11.2
2-29
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Draft Regulatory Impact Analysis
Jarbidge
Joshua Tree
Joyce Kilmer - Slickrock
Kalmiopsis
Kings Canyon
La Garita
Lassen Volcanic
Lava Beds
Linville Gorge
Lostwood
Lye Brook
Mammoth Cave
Marble Mountain
Maroon Bells - Snowmass
Mazatzal
Medicine Lake
Mesa Verde
Mingo
Mission Mountains
Mokelumne
Moosehorn
Mount Hood
Mount Jefferson
Mount Rainier
Mount Washington
Mount Zirkel
North Cascades
Okefenokee
Otter Creek
Pasayten
Petrified Forest
Pine Mountain
Presidential Range - Dry
Rawah
Red Rock Lakes
Redwood
Rocky Mountain
Roosevelt Campobello
Salt Creek
San Gorgonio
San Jacinto
San Pedro Parks
Sawtooth
Scapegoat
Selway - Bitterroot
Seney
Sequoia
Shenandoah
Sierra Ancha
Sipsey
South Warner
Strawberry Mountain
Superstition
Swanquarter
NV
CA
NC
OR
CA
CO
CA
CA
NC
ND
VT
KY
CA
CO
AZ
MT
CO
MO
MT
CA
ME
OR
OR
WA
OR
CO
WA
GA
WV
WA
AZ
AZ
NH
CO
WY
CA
CO
ME
NM
CA
CA
NM
ID
MT
MT
MI
CA
VA
AZ
AL
CA
OR
AZ
NC
12.6
19.5
29.5
14.8
23.5
11.6
14.8
16.6
27.9
19.6
23.9
30.2
17.1
11.3
13.1
17.7
12.8
27.5
14.2
12.9
21.4
14.0
15.7
18.9
15.7
11.7
14.0
26.4
27.6
14.7
13.5
13.1
23.2
11.7
12.1
16.5
14.1
21.4
17.7
21.5
21.5
11.4
13.6
14.2
12.3
23.8
23.5
27.6
13.4
28.7
16.6
19.6
14.7
24.6
12.8
20.3
26.1
14.4
24.1
11.5
14.6
16.5
24.6
18.7
21.1
27.0
16.8
11.3
13.5
17.1
12.8
25.9
14.0
12.8
20.3
13.7
15.2
19.4
15.2
11.8
14.0
24.7
24.0
14.5
13.8
13.4
20.9
11.7
12.1
16.5
14.1
20.1
17.3
22.1
21.4
11.4
13.5
14.1
12.1
22.6
24.1
23.4
13.7
26.1
16.5
19.2
15.0
21.9
7.1
7.1
11.5
7.7
7.1
7.1
7.3
7.5
11.4
7.3
11.3
11.5
7.7
7.1
6.9
7.3
7.1
11.3
7.4
7.1
11.4
7.8
7.8
7.9
7.9
7.1
7.8
11.5
11.3
7.8
7.0
6.9
11.3
7.1
7.1
7.8
7.1
11.4
7.0
7.1
7.1
7.0
7.2
7.3
7.3
11.4
7.1
11.3
6.9
11.4
7.3
7.5
6.9
11.2
2-30
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Air Quality, Health, and Welfare Concerns
Sycamore Canyon
Teton
Theodore Roosevelt
Thousand Lakes
Three Sisters
ULBend
Upper Buffalo
Voyageurs
Weminuche
West Elk
Wind Cave
Wolf Island
Yellowstone
YollaBolly- Middle Eel
Yo Semite
Zion
AZ
WY
ND
CA
OR
MT
AR
MN
CO
CO
SD
GA
WY
CA
CA
UT
16.1
12.1
17.6
14.8
15.7
14.7
25.5
18.4
11.6
11.3
16.0
26.4
12.1
17.1
17.6
13.5
16.6
12.1
16.8
14.6
15.2
14.1
24.3
17.6
11.4
11.3
15.4
24.9
12.1
16.9
17.4
13.3
7.0
7.1
7.3
7.3
7.9
7.2
11.3
11.1
7.1
7.1
7.2
11.4
7.1
7.4
7.1
7.0
a 116 IMPROVE sites represent 155 of the 156 Mandatory Class I Federal Areas. One isolated Mandatory Class I
Federal Area (Bering Sea, an uninhabited and infrequently visited island 200 miles from the coast of Alaska), was
considered to be so remote from electrical power and people that it would be impractical to collect routine aerosol
samples.87
b The deciview metric describes perceived visual changes in a linear fashion over its entire range, analogous to the
decibel scale for sound. A deciview of 0 represents pristine conditions. The higher the deciview value, the worse the
visibility, and an improvement in visibility is a decrease in deciview value.
0 The 2015 modeling projections are based on the Clear Air Interstate Rule analyses (EPA, 2005).
2.2.4.2 Atmospheric Deposition
Wet and dry deposition of ambient particulate matter delivers a complex mixture of
metals (e.g., mercury, zinc, lead, nickel, aluminum, cadmium), organic compounds (e.g., POM,
dioxins, furans) and inorganic compounds (e.g., nitrate, sulfate) to terrestrial and aquatic
ecosystems. The chemical form of the compounds deposited is impacted by a variety of factors
including ambient conditions (e.g., temperature, humidity, oxidant levels) and the sources of the
material. Chemical and physical transformations of the parti culate compounds occur in the
atmosphere as well as the media onto which they deposit. These transformations in turn
influence the fate, bioavailability and potential toxicity of these compounds. Atmospheric
deposition has been identified as a key component of the environmental and human health
hazard posed by several pollutants including mercury, dioxin and PCBs.88
Adverse impacts on water quality can occur when atmospheric contaminants deposit to
the water surface or when material deposited on the land enters a waterbody through runoff.
Potential impacts of atmospheric deposition to waterbodies include those related to both nutrient
and toxic inputs. Adverse effects to human health and welfare can occur from the addition of
excess paniculate nitrate nutrient enrichment which contributes to toxic algae blooms and zones
of depleted oxygen, which can lead to fish kills, frequently in coastal waters. Particles
contaminated with heavy metals or other toxins may lead to the ingestion of contaminated fish,
ingestion of contaminated water, damage to the marine ecology, and limited recreational uses.
Several studies have been conducted in U.S. coastal waters and in th^^e^t Lakes Region in
which the role of ambient PM deposition and runoff is investigated.
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Draft Regulatory Impact Analysis
Adverse impacts on soil chemistry and plant life have been observed for areas heavily
impacted by atmospheric deposition of nutrients, metals and acid species, resulting in species
shifts, loss of biodiversity, forest decline and damage to forest productivity. Potential impacts
also include adverse effects to human health through ingestion of contaminated vegetation or
livestock (as in the case for dioxin deposition), reduction in crop yield, and limited use of land
due to contamination.
2.2.4.2.1 Acid Deposition
Acid deposition, or acid rain as it is commonly known, occurs when NOx and SO2 react
in the atmosphere with water, oxygen, and oxidants to form various acidic compounds that later
fall to earth in the form of precipitation or dry deposition of acidic particles.94 It contributes to
damage of trees at high elevations and in extreme cases may cause lakes and streams to become
so acidic that they cannot support aquatic life. In addition, acid deposition accelerates the decay
of building materials and paints, including irreplaceable buildings, statues, and sculptures that
are part of our nation's cultural heritage.
Acid deposition primarily affects bodies of water that rest atop soil with a limited ability
to neutralize acidic compounds. The National Surface Water Survey (NSWS) investigated the
effects of acidic deposition in over 1,000 lakes larger than 10 acres and in thousands of miles of
streams. It found that acid deposition was the primary cause of acidity in 75 percent of the
acidic lakes and about 50 percent of the acidic streams, and that the areas most sensitive to acid
rain were the Adirondacks, the mid-Appalachian highlands, the upper Midwest and the high
elevation West. The NSWS found that approximately 580 streams in the Mid-Atlantic Coastal
Plain are acidic primarily due to acidic deposition. Hundreds of the lakes in the Adirondacks
surveyed in the NSWS have acidity levels incompatible with the survival of sensitive fish
species. Many of the over 1,350 acidic streams in the Mid-Atlantic Highlands (mid-Appalachia)
region have already experienced trout losses due to increased stream acidity. Emissions from
U.S. sources contribute to acidic deposition in Eastern Canada, where the Canadian government
has estimated that 14,000 lakes are acidic. Acid deposition also has been implicated in
contributing to degradation of high-elevation spruce forests that populate the ridges of the
Appalachian Mountains from Maine to Georgia. This area includes national parks such as the
Shenandoah and Great Smoky Mountain National Parks.
A study of emission trends and acidity of water bodies in the Eastern United States by the
General Accounting Office (GAO) found that from 1992 to 1999 sulfates declined in 92 percent
of a representative sample of lakes, and nitrate levels increased in 48 percent of the lakes
sampled.95 The decrease in sulfates is consistent with emission trends, but the increase in
nitrates is inconsistent with the stable levels of nitrogen emissions and deposition. The study
suggests that the vegetation and land surrounding these lakes have lost some of their previous
capacity to use nitrogen, thus allowing more of the nitrogen to flow into the lakes and increase
their acidity. Recovery of acidified lakes is expected to take a number of years, even where soil
and vegetation have not been "nitrogen saturated," as EPA called the phenomenon in a 1995
study.96 This situation places a premium on reductions of NOx from all sources, including Small
SI and Marine SI engines, vessels and equipment in order to reduce the extent and severity of
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Air Quality, Health, and Welfare Concerns
nitrogen saturation and acidification of lakes in the Adirondacks and throughout the United
States.
The NOx reductions from this rule would help reduce acid rain and acid deposition,
thereby helping to reduce acidity levels in lakes and streams throughout the country and helping
accelerate the recovery of acidified lakes and streams and the revival of ecosystems adversely
affected by acid deposition. Reduced acid deposition levels will also help reduce stress on
forests, thereby accelerating reforestation efforts and improving timber production.
Deterioration of our historic buildings and monuments, and of buildings, vehicles, and other
structures exposed to acid rain and dry acid deposition also will be reduced, and the costs borne
to prevent acid-related damage may also decline. While the reduction in nitrogen acid
deposition will be roughly proportional to the reduction in NOx emissions, respectively, the
precise impact of this proposed rule will differ across different areas.
2.2.4.2.2 Eutrophication, Nitrification and Fertilization
In recent decades, human activities have greatly accelerated nutrient impacts, such as
nitrogen deposition in both aquatic and terrestrial systems. Nitrogen deposition in aquatic
systems can cause excessive growth of algae and lead to degraded water quality and associated
impairment of fresh water and estuarine resources for human uses.97 Nitrogen deposition on
terrestrial systems can cause fertilization and lead to ecosystem stress and species shift.
Eutrophication is the accelerated production of organic matter, particularly algae, in a
water body. This increased growth can cause numerous adverse ecological effects and economic
impacts, including nuisance algal blooms, dieback of underwater plants due to reduced light
penetration, and toxic plankton blooms. Algal and plankton blooms can also reduce the level of
dissolved oxygen, which can adversely affect fish and shellfish populations.
Deposition of nitrogen contributes to elevated nitrogen levels in waterbodies. The NOX
reductions from today's promulgated standards will help reduce the airborne nitrogen deposition
that contributes to eutrophication of watersheds, particularly in aquatic systems where
atmospheric deposition of nitrogen represents a significant portion of total nitrogen loadings.
Severe and persistent eutrophication often directly impacts human activities. For
example, losses in the nation's fishery resources may be directly caused by fish kills associated
with low dissolved oxygen and toxic blooms. Declines in tourism occur when low dissolved
oxygen causes noxious smells and floating mats of algal blooms create unfavorable aesthetic
conditions. Risks to human health increase when the toxins from algal blooms accumulate in
edible fish and shellfish, and when toxins become airborne, causing respiratory problems due to
inhalation. According to the NOAA report, more than half of the nation's estuaries have
moderate to high expressions of at least one of these symptoms - an indication that
eutrophication is well developed in more than half of U.S. estuaries.98
In its Third Report to Congress on the Great Waters, EPA reported that atmospheric
deposition contributes from 2 to 38 percent of the nitrogen load to certain coastal waters.99 A
2-33
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Draft Regulatory Impact Analysis
review of peer reviewed literature in 1995 on the subject of air deposition suggests a typical
contribution of 20 percent or higher.100 Human-caused nitrogen loading to the Long Island
Sound from the atmosphere was estimated at 14 percent by a collaboration of federal and state
air and water agencies in 1997.101 The National Exposure Research Laboratory, U.S. EPA,
estimated based on prior studies that 20 to 35 percent of the nitrogen loading to the Chesapeake
Bay is attributable to atmospheric deposition.102 The mobile source portion of atmospheric NOx
contribution to the Chesapeake Bay was modeled at about 30 percent of total air deposition.103
In U.S. terrestrial systems, the nutrient whose supply most often sets the limit of possible
plant based productivity at a given site is nitrogen. By increasing available nitrogen, overall
ecosystem productivity may be expected to increase for a time, and then decline as nitrogen
saturation is reached. However, because not all vegetation, organisms, or ecosystems react in the
same manner to increased nitrogen fertilization, those plants or organisms that are predisposed to
capitalize on any increases in nitrogen availability gain an advantage over those that are not as
responsive to added nutrients, leading to a change in plant community composition and diversity.
Changes to plant community composition and structure within an ecosystem are of concern
because plants in large part determine the food supply and habitat types available for use by
other organisms. Further, in terrestrial systems, plants serve as the integrators between above-
ground and below-ground environments and influence nutrient, energy and water cycles.
Because of these linkages, chronic excess nutrient nitrogen additions can lead to complex,
dramatic, and severe ecosystem level responses such as changes in habitat suitability, genetic
diversity, community dynamics and composition, nutrient status, energy and nutrient cycling,
and frequency and intensity of natural disturbance regimes such as fire.
These types of effects have been observed both experimentally and in the field. For
example, experimental additions of nitrogen to a Minnesota grassland dominated by native
warm-season grasses produced a shift to low-diversity mixtures dominated by coolseason
grasses over a 12 year period at all but the lowest rate of nitrogen addition.104 Similarly, the
coastal sage scrub (CSS) community in California has been declining in land area and in drought
deciduous shrub density over the past 60 years, and is being replaced in many areas by the more
nitrogen responsive Mediterranean annual grasses. Some 25 plant species are already extinct in
California, most of them annual and perennial forbs that occurred in sites now experiencing
conversion to annual grassland. As CSS converts more extensively to annual grassland
dominated by invasive species, loss of additional rare species may be inevitable. Though
invasive species are often identified as the main threat to rare species, it is more likely that
invasive species combine with other factors, such as excess N deposition, to promote increased
productivity of invasive species and resulting species shifts.
Deposition of nitrogen from the engines covered in this proposal contributes to elevated
nitrogen levels in bodies of water and on land. The NOx reductions proposed in this action will
reduce the airborne nitrogen deposition that contributes to eutrophication of watersheds and
nitrogen saturation on land.
2.2.4.2.3 Heavy Metals
2-34
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Air Quality, Health, and Welfare Concerns
Heavy metals, including cadmium, copper, lead, chromium, mercury, nickel and zinc,
have the greatest potential for influencing forest growth (PM AQCD, p. 4-87).105 Investigation
of trace metals near roadways and industrial facilities indicate that a substantial burden of heavy
metals can accumulate on vegetative surfaces. Copper, zinc, and nickel have been documented
to cause direct toxicity to vegetation under field conditions (PM AQCD, p. 4-75). Little research
has been conducted on the effects associated with mixtures of contaminants found in ambient
PM. While metals typically exhibit low solubility, limiting their bioavailability and direct
toxicity, chemical transformations of metal compounds occur in the environment, particularly in
the presence of acidic or other oxidizing species. These chemical changes influence the mobility
and toxicity of metals in the environment. Once taken up into plant tissue, a metal compound can
undergo chemical changes, accumulate and be passed along to herbivores or can re-enter the soil
and further cycle in the environment.
Although there has been no direct evidence of a physiological association between tree
injury and heavy metal exposures, heavy metals have been implicated because of similarities
between metal deposition patterns and forest decline (PM AQCD, p. 4-76).106 Contamination of
plant leaves by heavy metals can lead to elevated soil levels. Some trace metals absorbed into
the plant and can bind to the leaf tissue (PM AQCD, p. 4-75). When these leaves fall and
decompose, the heavy metals are transferred into the soil.107'108
The environmental sources and cycling of mercury are currently of particular concern
due to the bioaccumulation and biomagnification of this metal in aquatic ecosystems and the
potent toxic nature of mercury in the forms in which is it ingested by people and other animals.
Mercury is unusual compared with other metals in that it largely partitions into the gas phase (in
elemental form), and therefore has a longer residence time in the atmosphere than a metal found
predominantly in the particle phase. This property enables a portion of emitted mercury to travel
far from the primary source before being deposited and accumulating in the aquatic ecosystem.
Localized or regional impacts are also observed for mercury emitted from combustion sources.
The major source of mercury in the Great Lakes is from atmospheric deposition, accounting for
approximately eighty percent of the mercury in Lake Michigan.109'110 Over fifty percent of the
mercury in the Chesapeake Bay has been attributed to atmospheric deposition.111 Overall, the
National Science and Technology Council (NSTC, 1999) identifies atmospheric deposition as
the primary source of mercury to aquatic systems. Forty-four states have issued health
advisories for the consumption offish contaminated by mercury; however, most of these
advisories are issued in areas without a mercury point source.
Elevated levels of zinc and lead have been identified in streambed sediments, and these
elevated levels have been correlated with population density and motor vehicle use.112'113 Zinc
and nickel have also been identified in urban water and soils. In addition, platinum, palladium,
and rhodium, metals found in the catalysts of modern motor vehicles, have been measured at
elevated levels along roadsides.114 Plant uptake of platinum has been observed at these
locations.
2.2.4.2.4 Poly cyclic Organic Matter
2-35
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Draft Regulatory Impact Analysis
Polycyclic organic matter (POM) is a byproduct of incomplete combustion and consists
of organic compounds with more than one benzene ring and a boiling point greater than or equal
to 100 degrees centigrade.115 Polycyclic aromatic hydrocarbons (PAHs) are a class of POM that
contains compounds which are known or suspected carcinogens.
Major sources of PAHs include mobile sources. PAHs in the environment may be
present as a gas or adsorbed onto airborne particulate matter. Since the majority of PAHs are
adsorbed onto particles less than 1.0 |_im in diameter, long range transport is possible. However,
studies have shown that PAH compounds adsorbed onto diesel exhaust particulate and exposed
to ozone have half lives of 0.5 to 1.0 hours.116
Since PAHs are insoluble, the compounds generally are particle reactive and accumulate
in sediments. Atmospheric deposition of particles is believed to be the major source of PAHs to
the sediments of Lake Michigan.117'118 Analyses of PAH deposition to Chesapeake and
Galveston Bay indicate that dry deposition and gas exchange from the atmosphere to the surface
water predominate.119'120 Sediment concentrations of PAHs are high enough in some segments
of Tampa Bay to pose an environmental health threat. EPA funded a study to better characterize
the sources and loading rates for PAHs into Tampa Bay.121 PAHs that enter a waterbody
through gas exchange likely partition into organic rich particles and be biologically recycled,
while dry deposition of aerosols containing PAHs tends to be more resistant to biological
recycling.122 Thus, dry deposition is likely the main pathway for PAH concentrations in
sediments while gas/water exchange at the surface may lead to PAH distribution into the food
web, leading to increased health risk concerns.
Trends in PAH deposition levels are difficult to discern because of highly variable
ambient air concentrations, lack of consistency in monitoring methods, and the significant
influence of local sources on deposition levels.123 Van Metre et al. (2000) noted PAH
concentrations in urban reservoir sediments have increased by 200-300% over the last forty
years and correlates with increases in automobile use.124
Cousins et al. (1999) estimates that greater than ninety percent of semi-volatile organic
compound (SVOC) emissions in the United Kingdom deposit on soil.125 An analysis of
polycyclic aromatic hydrocarbon (PAH) concentrations near a Czechoslovakian roadway
indicated that concentrations were thirty times greater than background.126
2.2.4.2.5 Materials Damage and Soiling
The deposition of airborne particles can also reduce the aesthetic appeal of buildings and
culturally important articles through soiling, and can contribute directly (or in conjunction with
other pollutants) to structural damage by means of corrosion or erosion.127 Particles affect
materials principally by promoting and accelerating the corrosion of metals, by degrading paints,
and by deteriorating building materials such as concrete and limestone. Particles contribute to
these effects because of their electrolytic, hygroscopic, and acidic properties, and their ability to
absorb corrosive gases (principally sulfur dioxide). The rate of metal corrosion depends on a
number of factors, including the deposition rate and nature of the pollutant; the influence of the
2-36
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Air Quality, Health, and Welfare Concerns
metal protective corrosion film; the amount of moisture present; variability in the
electrochemical reactions; the presence and concentration of other surface electrolytes; and the
orientation of the metal surface.
2.3 Gaseous Air Toxics
Small SI and Marine SI emissions contribute to ambient levels of gaseous air toxics
known or suspected as human or animal carcinogens, or that have non-cancer health effects.
These compounds include benzene, 1,3-butadiene, formaldehyde, acetaldehyde, acrolein,
poly cyclic organic matter (POM), and naphthalene. All of these compounds, except
acetaldehyde, were identified as national or regional risk drivers in the 1999 National-Scale Air
Toxics Assessment (NATA) and have significant inventory contributions from mobile sources.
The reductions in Small SI and Marine SI emissions proposed in this rulemaking would help
reduce exposure to these harmful substances.
Air toxics can cause a variety of cancer and noncancer health effects. A number of the
mobile source air toxic pollutants described in this section are known or likely to pose a cancer
hazard in humans. Many of these compounds also cause adverse noncancer health effects
resulting from chronic,16 subchronic,17 or acute18 inhalation exposures. These include
neurological, cardiovascular, liver, kidney, and respiratory effects as well as effects on the
immune and reproductive systems.
Benzene: The EPA's IRIS database lists benzene as a known human carcinogen (causing
leukemia) by all routes of exposure, and that exposure is associated with additional health
effects, including genetic changes in both humans and animals and increased proliferation of
bone marrow cells in mice.128'129' 13° EPA states in its IRIS database that data indicate a causal
relationship between benzene exposure and acute lymphocytic leukemia and suggests a
relationship between benzene exposure and chronic non-lymphocytic leukemia and chronic
lymphocytic leukemia. A number of adverse noncancer health effects including blood disorders,
such as preleukemia and aplastic anemia, have also been associated with long-term exposure to
benzene.131'132 The most sensitive noncancer effect observed in humans, based on current data,
is the depression of the absolute lymphocyte count in blood.133'134 In addition, recent work,
including studies sponsored by the Health Effects Institute (HEI), provides evidence that
biochemical responses are occurring at lower levels of benzene exposure than previously known.
135, Be, 137,138 EpA's jRjg prOgram has not yet evaluated these new data.
16Chronic exposure is defined in the glossary of the Integrated Risk Information (IRIS) database
(http://www.epa.gov/iris) as repeated exposure by the oral, dermal, or inhalation route for more than approximately
10 of the life span in humans (more than approximately 90 days to 2 years in typically used laboratory animal
species).
"Defined in the IRIS database as exposure to a substance spanning approximately 10 of the lifetime of an
organism.
18Defined in the IRIS database as exposure by the oral, dermal, or inhalation route for 24 hours or less.
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Draft Regulatory Impact Analysis
1.3-Butadiene: EPA has characterized 1,3-butadiene as carcinogenic to humans by
inhalation.139' 14° The specific mechanisms of 1,3-butadiene-induced carcinogenesis are
unknown. However, it is virtually certain that the carcinogenic effects are mediated by
genotoxic metabolites of 1,3-butadiene. Animal data suggest that females may be more sensitive
than males for cancer effects; while there are insufficient data in humans from which to draw
conclusions about sensitive subpopulations. 1,3-Butadiene also causes a variety of reproductive
and developmental effects in mice; no human data on these effects are available. The most
sensitive effect was ovarian atrophy observed in a lifetime bioassay of female mice.141
Formaldehyde: Since 1987, EPA has classified formaldehyde as a probable human
carcinogen based on evidence in humans and in rats, mice, hamsters, and monkeys.142 EPA's
current IRIS summary provides an upper bound cancer unit risk estimate of 1.3xlO"5 per |ig/m3.
In other words, there is an estimated risk of about thirteen excess cancer cases in one million
people exposed to 1 |ig/m3 of formaldehyde over a lifetime. EPA is currently reviewing recently
published epidemiological data. For instance, research conducted by the National Cancer
Institute (NCI) found an increased risk of nasopharyngeal cancer and lymphohematopoietic
malignancies such as leukemia among workers exposed to formaldehyde.143'144 NCI is currently
performing an update of these studies. A recent National Institute of Occupational Safety and
Health (NIOSH) study of garment workers also found increased risk of death due to leukemia
among workers exposed to formaldehyde.145 In 2004, the working group of the International
Agency for Research on Cancer (IARC) concluded that formaldehyde is carcinogenic to humans
(Group 1), on the basis of sufficient evidence in humans and sufficient evidence in experimental
animals—a higher classification than previous IARC evaluations. The agency is currently
conducting a reassessment of the human hazard and dose-response associated with
formaldehyde.
In the past 15 years there has been substantial research on the inhalation dosimetry for
formaldehyde in rodents and primates by the CUT Centers for Health Research (formerly the
Chemical Industry Institute of Toxicology), with a focus on use of rodent data for refinement of
the quantitative cancer dose-response assessment.146'147> 148 CIIT's risk assessment of
formaldehyde incorporated mechanistic and dosimetric information on formaldehyde. The risk
assessment analyzed carcinogenic risk from inhaled formaldehyde using approaches that are
consistent with EPA's draft guidelines for carcinogenic risk assessment. In 2001, Environment
Canada relied on this cancer dose-response assessment in their assessment of formaldehyde.149
Extended follow-up of a cohort of British chemical workers did not find evidence of an increase
in nasopharyngeal or lymphohematopoetic cancers, but a continuing statistically significant
excess in lung cancers was reported.150
Based on the developments of the last decade, in 2004, EPA also relied on this cancer
unit risk estimate during the development of the plywood and composite wood products national
emissions standards for hazardous air pollutants (NESHAPs).151 In these rules, EPA concluded
that the CUT work represented the best available application of the available mechanistic and
dosimetric science on the dose-response for portal of entry cancers due to formaldehyde
exposures. EPA is reviewing the recent work cited above from the NCI and NIOSH, as well as
the analysis by the CUT Centers for Health Research and other studies, as part of a reassessment
2-38
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Air Quality, Health, and Welfare Concerns
of the human hazard and dose-response associated with formaldehyde.
Formaldehyde exposure also causes a range of noncancer health effects, including
irritation of the eyes (tearing of the eyes and increased blinking) and mucous membranes.
Acetaldehyde: Acetaldehyde is classified in EPA's IRIS database as a probable human
carcinogen, based on nasal tumors in rats, and is considered moderately toxic by the inhalation,
oral, and intravenous routes.152 The primary acute effect of exposure to acetaldehyde vapors is
irritation of the eyes, skin, and respiratory tract.153 The agency is currently conducting a
reassessment of the health hazards from inhalation exposure to acetaldehyde.
Acrolein: Acrolein is intensely irritating to humans when inhaled, with acute exposure
resulting in upper respiratory tract irritation and congestion. EPA determined in 2003 using the
1999 draft cancer guidelines that the human carcinogenic potential of acrolein could not be
determined because the available data was inadequate. No information was available on the
carcinogenic effects of acrolein in humans, and the animal data provided inadequate evidence of
carcinogen! city.154
Poly cyclic Organic Matter (POM): POM is generally defined as a large class of organic
compounds which have multiple benzene rings and a boiling point greater than 100 degrees
Celsius. One of these compounds, naphthalene, is discussed separately below. Poly cyclic
aromatic hydrocarbons (PAH) are a class of POM that contain only hydrogen and carbon atoms.
A number of PAHs are known or suspected carcinogens.
Recent studies have found that maternal exposures to PAHs in a population of pregnant
women were associated with several adverse birth outcomes, including low birth weight and
reduced length at birth as well as impaired cognitive development at age three.155156 EPA has not
yet evaluated these recent studies.
Naphthalene: Naphthalene is found in small quantities in gasoline and diesel fuels.
Naphthalene emissions have been measured in larger quantities in both gasoline and diesel
exhaust and evaporative emissions from mobile sources. EPA recently released an external
review draft of a reassessment of the inhalation carcinogenicity of naphthalene based on a
number of recent animal carcinogenicity studies.157 The draft reassessment recently completed
external peer review.158 California EPA has also released a new risk assessment for naphthalene,
and the IARC has reevaluated naphthalene and re-classified it as Group 2B: possibly
carcinogenic to humans.159 Naphthalene also causes a number of chronic non-cancer effects in
animals, including abnormal cell changes and growth in respiratory and nasal tissues.160
In addition to reducing VOC, NOx, CO and PM2 5 emissions from Small SI engines and
equipment and Marine SI engines and vessels the standards being proposed today would also
reduce air toxics emitted from these engines, vessels and equipment thereby helping to mitigate
some of the adverse health effects associated with operation of these engines, vessels and
equipment.
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Draft Regulatory Impact Analysis
2.4 Carbon Monoxide
Unlike many gases, CO is odorless, colorless, tasteless, and nonirritating. Carbon
monoxide results from incomplete combustion of fuel and is emitted directly from vehicle
tailpipes. Incomplete combustion is most likely to occur at low air-to-fuel ratios in the engine.
These conditions are common during vehicle starting when air supply is restricted ("choked"),
when vehicles are not tuned properly, and at high altitude, where "thin" air effectively reduces
the amount of oxygen available for combustion (except in engines that are designed or adjusted
to compensate for altitude). High concentrations of CO generally occur in areas with elevated
mobile-source emissions. Carbon monoxide emissions increase dramatically in cold weather.
This is because engines need more fuel to start at cold temperatures and because some emission
control devices (such as oxygen sensors and catalytic converters) operate less efficiently when
they are cold. Also, nighttime inversion conditions are more frequent in the colder months of the
year. This is due to the enhanced stability in the atmospheric boundary layer, which inhibits
vertical mixing of emissions from the surface.
2.4.1 Health Effects of CO Pollution
We are relying on the data and conclusions in the EPA Air Quality Criteria Document for
CO (CO Criteria Document) regarding the health effects associated with CO exposure.161
Carbon monoxide enters the bloodstream through the lungs and forms carboxyhemoglobin
(COHb), a compound that inhibits the blood's capacity to carry oxygen to organs and tissues.162'
163 Carbon monoxide has long been known to have substantial adverse effects on human health,
including toxic effects on blood and tissues, and effects on organ functions. Although there are
effective compensatory increases in blood flow to the brain, at some concentrations of COHb,
somewhere above 20 percent, these compensations fail to maintain sufficient oxygen delivery,
and metabolism declines.164 The subsequent hypoxia in brain tissue then produces behavioral
effects, including decrements in continuous performance and reaction time.165
Carbon monoxide has been linked to increased risk for people with heart disease, reduced
visual perception, cognitive functions and aerobic capacity, and possible fetal effects.166 Persons
with heart disease are especially sensitive to carbon monoxide poisoning and may experience
chest pain if they breathe the gas while exercising.167 Infants, elderly persons, and individuals
with respiratory diseases are also particularly sensitive. Carbon monoxide can affect healthy
individuals, impairing exercise capacity, visual perception, manual dexterity, learning functions,
and ability to perform complex tasks.168
Several epidemiological studies have shown a link between CO and premature morbidity
(including angina, congestive heart failure, and other cardiovascular diseases). Several studies in
the United States and Canada have also reported an association between ambient CO exposures
and frequency of cardiovascular hospital admissions, especially for congestive heart failure
(CHF). An association between ambient CO exposure and mortality has also been reported in
epidemiological studies, though not as consistently or specifically as with CHF admissions.
EPA reviewed these studies as part of the CO Criteria Document review process and noted the
possibility that the average ambient CO levels used as exposure indices in the epidemiology
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Air Quality, Health, and Welfare Concerns
studies may be surrogates for ambient air mixes impacted by combustion sources and/or other
constituent toxic components of such mixes. More research will be needed to better clarify CO's
role.169
As noted above, CO has been linked to numerous health effects. In addition to health
effects from chronic exposure to ambient CO levels, acute exposures to higher levels are also a
problem. Acute exposures to CO are discussed further in Section 2.5.
2.4.2 Attainment and Maintenance of the CO NAAQS
On July 3, 1995 EPA made a finding that small land-based spark-ignition engines cause
or contribute to CO nonattainment (60 FR 34581, July 3, 1995). Marine spark-ignition engines,
which have relatively high per engine CO emissions, can also be a source of CO emissions in
CO nonattainment areas. In the preamble for this proposed rule EPA makes a finding that
recreational marine engines and vessels cause or contribute to CO nonattainment and we provide
information showing CO emissions from spark-ignition marine engines and vessels in the CO
nonattainment areas in 2005. Spark-ignition marine engines and vessels contribute to CO
nonattainment in more than one of the CO nonattainment areas.
A nonattainment area is defined in the Clean Air Act (CAA) as an area that is violating
an ambient standard or is contributing to a nearby area that is violating the standard. EPA has
designated nonattainment areas for the CO NAAQS by calculating air quality design values and
considering other factors.19
There are two CO NAAQS. The 8-hour average CO NAAQS is 9 ppm, not to be
exceeded more than once per year, and the 1-hour average CO NAAQS is 35 ppm, not to be
exceeded more than once per year. As of October 26, 2006, there are approximately 15 million
people living in 6 areas (which include 10 counties) that are designated as nonattainment for CO,
see Table 2.4-1. The emission reductions proposed in this action would help areas to attain and
maintain the CO NAAQS.
Table 2.4-1: Classified Carbon Monoxide Nonattainment Areas as of October 2006a
Area
Las Vegas, NV
Los Angeles South Coast Air Basin
El Paso, TX
Missoula, MT
Reno, NV
Total
Classification
serious
serious
moderate <= 12.7 ppm
moderate <= 12.7 ppm
moderate <= 12.7 ppm
Peculation (lOGOs1)
479
14,594
62
52
179
15.365
a This table does not include Salem, OR which is an unclassified CO nonattainment area.
In addition to the CO nonattainment areas, there are areas that have not been designated
as nonattainment where air quality monitoring may indicate a need for CO control. For example,
19 The full details involved in calculating a CO design value are given in 40 CFR Part 50.8.
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Draft Regulatory Impact Analysis
areas like Birmingham, AL and Calexico, CA have not been designated as nonattainment
although monitors in these areas have recorded multiple exceedances since 1995.170
There are also over 54 million people living in CO maintenance areas, see Table 2.4-2.20
Carbon monoxide maintenance areas may remain at risk for high CO episodes especially in
geographic areas with unusually challenging meteorological and topographical conditions and in
areas with high population growth and increasing vehicle miles traveled.
Table 2.4-2: Carbon Monoxide Maintenance Areas as of October 2006
Serious
Moderate > 12.7ppm
Moderate <= 12.7ppm
Unclassified
Total
Number of Areas
5
4
30
33
72
Number of Counties
11
19
61
41
132
Population (1000s)
5,902
17,576
23,319
7,544
54,341
A 2003 NAS report found that in geographical areas that have achieved attainment of the
NAAQS, it might still be possible for ambient concentrations of CO to sporadically exceed the
standard under unfavorable conditions such as strong winter inversions. Areas like Alaska are
prone to winter inversions due to their topographic and meteorologic conditions. The report
further suggests that additional reductions in CO are prudent to further reduce the risk of
violations in regions with problematic topography and temporal variability in meteorology.171
The reductions in CO emissions from this proposed rule could assist areas in maintaining the CO
standard.
As discussed in the preamble, Small SI engines and equipment and Marine SI engines
and vessels do contribute to CO nonattainment. The CO emission benefits from this rule would
help states in their strategy to attain the CO NAAQS. Maintenance of the CO NAAQS is also
challenging and many areas would be able to use the emissions reductions from this proposed
rule to assist in maintaining the CO NAAQS into the future.
2.5 Acute Exposure to Air Pollutants
Emissions from Small SI engines and equipment and Marine SI engines and vessels
contribute to ambient concentrations of ozone, CO, air toxics and PM and acute exposures to CO
and PM. As mentioned in Section II.B.4 of the preamble for this proposal, elevated exposures to
20The CO nonattainment and maintenance areas are listed in a Memo to the Docket titled "Nonattainment
Areas and Mandatory Class I Federal Areas" and contained in Docket EPA-HQ-OAR-2004-0008.
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Air Quality, Health, and Welfare Concerns
CO from Marine SI engines and vessels have been well documented. As mentioned in Sections
II.B.2 and II.B.4 of the preamble, elevated exposures to CO and PM can occur as a result of
operating Small SI engines and equipment. The standards being proposed in this action can help
reduce acute exposures to CO and PM from Marine SI engines and vessels and Small SI engines
and equipment.
2.5.1 Exposure to CO from Marine SI Engines and Vessels
In recent years, a substantial number of carbon monoxide (CO) poisonings and deaths
have occurred on and around recreational boats across the nation. The actual number of deaths
attributable to CO poisoning while boating is difficult to estimate because CO-related deaths in
the water may be labeled as drowning. An interagency team consisting of the National Park
Service, the U.S. Department of Interior, and the National Institute for Occupational Safety and
Health maintains a record of published CO-related fatal and nonfatal poisonings.172 Between
1984 and 2004, 113 CO-related deaths and 458 non-fatal CO poisonings have been identified
based on hospital records, press accounts, and other information. Deaths have been attributed to
exhaust from both onboard generators and propulsion engines. Houseboats, cabin cruisers, and
ski boats are the most common types of boats associated with CO poisoning cases. These
incidents have prompted other federal agencies, including the United States Coast Guard and
National Park Service, to issue advisory statements and other interventions to boaters to avoid
activities that could lead to excessive CO exposure.173
CO concentrations can be extremely elevated within several meters of the exhaust port.
Engineers and industrial hygienists from CDC/NIOSH and other state and federal agencies have
conducted field studies of CO concentrations on and around houseboats. In one study of
houseboat concentrations, CO concentrations immediately at the point of generator exhaust
discharge on one houseboat averaged 0.5% (5,000 ppm), and ranged from 0.0% to 1.28%
(12,800 ppm).174 With both propulsion and generators running, time-averaged concentrations on
the swim deck were 0.2 - 169 ppm at different locations on one boat's swim platform, 17-570
ppm on another's, and 0-108 on another. Other studies also show the potential for high
concentrations with extreme peaks in CO concentrations in locations where boaters and
swimmers can be exposed during typical boating activities, such as standing on a swim deck or
swimming near a boat.
2.5.2 Exposure to CO and PM from Small SI Engines and Equipment
A large segment of the population uses small, gasoline-powered spark-ignition (SI) lawn
and garden equipment on a regular basis. Emissions from many of the Small SI engines
powering this equipment may lead to elevated air pollution exposures for a number of gaseous
and particulate compounds, especially for individuals such as landscapers, whose occupations
require the daily use of these engines and equipment.
Emission studies with lawn and garden equipment suggest a potential for high exposures
during the Small SI engine operation.175'176 Studies investigating air pollutant exposures during
small engine use did report elevated personal exposure measurements related to lawn and garden
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Draft Regulatory Impact Analysis
equipment use.177'178 Bunger et al. reported elevated CO personal measurements related to
chainsaw use, with short-term concentrations exceeding 400 ppm for certain cutting activities.
This study evaluated personal exposures during the use of uncontrolled chainsaws. Baldauf at al.
evaluated the use of lawnmowers, chainsaws and string trimmers meeting US EPA Phase 2
standards. In this study, short-term exposures during lawnmower and chainsaw use exceeded
120 ppm of CO, while string trimmer use resulted in some short-term exposures approaching 100
ppm of CO. This study also indicated that short-term PM25 exposures could exceed 100 |ig/m3.
Pollutant exposures were highly dependent on the operator's orientation to the engine and wind
direction, as well as the activities being conducted.
These studies indicate that emissions from some lawn and garden equipment meeting
EPA's current Phase 2 standards may result in exposures to certain pollutants at levels of concern
for adverse health effects. The potential for elevated exposure to CO and PM2 5 for operators of
Small SI engines and equipment would be reduced by this proposed rule.
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Air Quality, Health, and Welfare Concerns
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Draft Regulatory Impact Analysis
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73.Kim, J.J.; Smorodinsky, S.; Lipsett, M.; Singer, B.C.; Hodgson, A.T.; Ostro, B (2004). Traffic-related air
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77. U. S. EPA (2005) Review of the National Ambient Air Quality Standard for Paniculate Matter: Policy
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80. U. S. EPA (2005) Review of the National Ambient Air Quality Standard for Paniculate Matter: Policy
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85. U.S. EPA. 1993. Effects of the 1990 Clean Air Act Amendments on Visibility in Class I Areas: An EPA Report
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88.U.S. EPA (2000) Deposition of Air Pollutants to the Great Waters: Third Report to Congress. Office of Air
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89.U.S. EPA (2004) National Coastal Condition Report II. Office of Research and Development/ Office of Water.
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94. Much of the information in this subsection was excerpted from the EPA document, Human Health Benefits from
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107.Cotrufo, M.F.; DeSanto, A.V.; Alfani, A.; et al. 1995. Effects of urban heavy metal pollution on organic matter
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115.U.S. EPA. 1998. EPA454/R-98-014, "Locating and Estimating Air Emissions from Sources of Polycyclic
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116.U.S. EPA. 1998. EPA454/R-98-014, "Locating and Estimating Air Emissions from Sources of Polycyclic
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123.U.S. EPA. 2000. EPA453/R-00-005, "Deposition of Air Pollutants to the Great Waters: Third Report to
Congress," Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina. This document is
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124.Van Metre, P.C.; Mahler, B.J.; and Furlong, E.T. 2000. Urban sprawl leaves its PAH signature." Environmental
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126.Tuhackova, I, Cajthaml, T.; Novak, K.; et al. 2001. Hydrocarbon deposition and soil microflora as affected by
highway traffic. Environmental Pollution, 113: 255-262.
127.U.S. EPA (2005) Review of the National Ambient Air Quality Standard for Paniculate Matter: Policy
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128.U.S. EPA (2000). Integrated Risk Information System File for Benzene. This material is available electronically
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129.1nternational Agency for Research on Cancer, IARC monographs on the evaluation of carcinogenic risk of
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134.EPA 2005 "Full IRIS Summary for Benzene (CASRN 71-43-2)" Environmental Protection Agency, Integrated
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Assessment Office, Cincinnati, OH http://www.epa.gov/iris/subst/0276.htm.
135.Qu, O.; Shore, R.; Li, G.; Jin, X.; Chen, C.L.; Cohen, B.; Melikian, A.; Eastmond, D.; Rappaport, S.; Li, H.;
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138.Turtletaub, K.W. and Mani, C. (2003). Benzene metabolism in rodents at doses relevant to human exposure
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Draft Regulatory Impact Analysis
139.U.S. EPA. (2002). Health Assessment of 1,3-Butadiene. Office of Research and Development, National Center
for Environmental Assessment, Washington Office, Washington, DC. Report No. EPA600-P-98-001F.
140.U.S. EPA (1998). A Science Advisory Board Report: Review of the Health Risk Assessment of 1,3-Butadiene.
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141.Bevan, C.; Stadler, J.C.; Elliot, G.S.; et al. (1996) Subchronic toxicity of 4-vinylcyclohexene in rats and mice by
inhalation. Fundam. Appl. Toxicol. 32:1-10.
142.U.S. EPA (1987). Assessment of Health Risks to Garment Workers and Certain Home Residents from Exposure
to Formaldehyde, Office of Pesticides and Toxic Substances, April 1987.
143.Hauptmann, M..; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.; Blair, A. 2003. Mortality from
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144.Hauptmann, M..; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.; Blair, A. 2004. Mortality from solid cancers
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146.Conolly, RB, JS Kimbell, D Janszen, PM Schlosser, D Kalisak, J Preston, and FJ Miller. 2003. Biologically
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147.Conolly, RB, JS Kimbell, D Janszen, PM Schlosser, D Kalisak, J Preston, and FJ Miller. 2004. Human
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148.Chemical Industry Institute of Toxicology (CUT). 1999. Formaldehyde: Hazard characterization and
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149.Health Canada (2001) Priority Substances List Assessment Report. Formaldehyde. Environment Canada, Health
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151.U.S. EPA (2004) National Emission Standards for Hazardous Air Pollutants for Plywood and Composite Wood
Products Manufacture: Final Rule. (69 FR 45943, 7/30/04)
152.U.S. EPA (1988). Integrated Risk Information System File of Acetaldehyde. This material is available
electronically at http://www.epa.gov/iris/subst/0290.htm.
153.U.S. EPA (1988). Integrated Risk Information System File of Acetaldehyde. This material is available
electronically at http://www.epa.gov/iris/subst/0290.htm.
154.1ntegrated Risk Information System File of Acrolein. Research and Development, National Center for
Environmental Assessment, Washington, DC. This material is available at http://www.epa.gov/iris/subst/0364.htm
155.Perera, F. P.; Rauh, V.; Tsai, W. Y. et al. (2003). Effects of transplacental exposure to environmental pollutants
on birth outcomes in a multiethnic population. Environ. Health Perspect. 111(2): 201-205.
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156. Perera, P.P.; Rauh, V.; Whyatt, R.M.; Tsai, W.Y.; Tang, D.; Diaz,D.; Hoepner, L.; Barr,D.; Tu,Y.H.; Camann,
D.; Kinney, P. (2006) Effect of prenatal exposure to airborne polycyclic aromatic hydrocarbons on
neurodevelopment in the first 3 years of life among inner-city children. Environ Health Perspect 114:1287-1292.
157.U. S. EPA. (2004). External Review Draft, IRIS Reassessment of the Inhalation Carcinogenicity of
Naphthalene, http://www.epa.gov/iris
158.Oak Ridge Institute for Science and Education. (2004). External Peer Review for the IRIS Reassessment of the
Inhalation Carcinogenicity of Naphthalene. August 2004.
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159.1nternational Agency for Research on Cancer (IARC). (2002). Monographs on the Evaluation of the
Carcinogenic Risk of Chemicals for Humans. Vol. 82. Lyon, France.
160.U. S. EPA. (1998). Integrated Risk Information System File of Naphthalene. This information is available
electronically at http://www.epa/gov/iris
161. U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide. EPA600-P-99-001F. June 1, 2000. U.S.
Environmental Protection Agency, Office of Research and Development, National Center for Environmental
Assessment, Washington, D.C. This document is available online at http://www.epa.gov/ncea/pdfs/coaqcd.pdf. A
copy of this document is available in Docket Identification EPA-HQ-OAR-2004-0008-0050.
162. U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide. EPA600-P-99-001F. June 1, 2000. U.S.
Environmental Protection Agency, Office of Research and Development, National Center for Environmental
Assessment, Washington, D.C. This document is available online at http://www.epa.gov/ncea/pdfs/coaqcd.pdf. A
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163. Coburn, R.F. (1979) Mechanisms of carbon monoxide toxicity. Prev. Med. 8:310-322.
164. Helfaer, M.A., and Traystman, R.J. (1996) Cerebrovascular effects of carbon monoxide. In: Carbon
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165. Benignus, V.A. (1994) Behavioral effects of carbon monoxide: meta analyses and extrapolations. J.Appl.
Physiol. 76:1310-1316.
166. U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide. EPA600-P-99-001F. June 1, 2000. U.S.
Environmental Protection Agency, Office of Research and Development, National Center for Environmental
Assessment, Washington, D.C. This document is available online at http://www.epa.gov/ncea/pdfs/coaqcd.pdf. A
copy of this document is available in Docket Identification EPA-HQ-OAR-2004-0008-0050.
167. U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide. EPA600-P-99-001F. June 1, 2000. U.S.
Environmental Protection Agency, Office of Research and Development, National Center for Environmental
Assessment, Washington, D.C. This document is available online at http://www.epa.gov/ncea/pdfs/coaqcd.pdf. A
copy of this document is available in Docket Identification EPA-HQ-OAR-2004-0008-0050.
168. U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide. EPA600-P-99-001F. June 1, 2000. U.S.
Environmental Protection Agency, Office of Research and Development, National Center for Environmental
Assessment, Washington, D.C. This document is available online at http://www.epa.gov/ncea/pdfs/coaqcd.pdf. A
copy of this document is available in Docket Identification EPA-HQ-OAR-2004-0008-0050.
169. U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide. EPA600-P-99-001F. June 1, 2000. U.S.
Environmental Protection Agency, Office of Research and Development, National Center for Environmental
Assessment, Washington, D.C. This document is available online at http://www.epa.gov/ncea/pdfs/coaqcd.pdf. A
copy of this document is available in Docket Identification EPA-HQ-OAR-2004-0008-0050.
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170. National Academy of Sciences (2003). Managing Carbon Monoxide Pollution in Meteorological and
Topographical Problem Areas. The National Academies Press, Washington, D.C. This document is available on the
internet at http://www.nap.edu.
171. National Academy of Sciences (2003). Managing Carbon Monoxide Pollution in Meteorological and
Topographical Problem Areas. The National Academies Press, Washington, D.C. This document is available on the
internet at http://www.nap.edu.
172.National Park Service: Department of Interior; National Institute for Occupational Safety and Health. (2004)
Boat-related carbon monoxide (CO) poisonings. Updated: October 2004 [Online at
http://safetynet.smis.doi.gov/thelistbystatelO-19-04.pdf] A copy of this document is available in Docket
Identification EPA-HQ-OAR-2004-0008-0106.
173.U.S. Department of Interior. (2004) Carbon monoxide dangers from generators and propulsion engines. On-
board boats - compilation of materials. [Online at http://safetynet.smis.doi.gov/COhouseboats.htm] A copy of this
document is available in Docket Identification EPA-HQ-OAR-2004-0008-0110.
174.Letter dated April 5, 2001 to Mr. John Stenseth, Fun Country Marine Industries, Inc., from Ronald M. Hall,
NIOSH.
175. Gabele, P. (1997) Exhaust emissions from four-stroke lawn mower engines. Air Waste Manage Assoc. 47:
945-952.
176. Priest, M.W.; Williams, D.J.; and Bridgman, H.A. (2000) Emissions from in-use lawn-mowers in Australia.
Atmos Environ. 34:657-664.
177. Bunger, I; Bombosch, F.; Mesecke, U.; and Hairier, E. (1997) Monitoring and analysis of occupational
exposure to chain saw exhausts. Am IndHyg Assoc J. 58:747-751.
178. Baldauf, R.; Fortune, C.; Weinstein, J.; Wheeler, M.; and Blanchard, F. (2006) Air contaminant exposures
during the operation of lawn and garden equipment. Journal of Exposure Science and Environmental Epidemiology.
16(4):362-370.
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Emission Inventory
CHAPTER 3: Emission Inventory
This chapter presents our analysis of the emission impact of the proposed rule for spark
ignition (SI) small nonroad engines (<25 horsepower (hp) or < 19 kilowatts (kW) used in land-
based or auxiliary marine applications (hereafter collectively termed small nonroad SI engines)
and Marine SI engines. The control requirements include exhaust and evaporative emission
standards for small non-handheld SI engines (Class I <225 cubic centimeters (cc) and Class II
>225 cc), an evaporative emission standards for small handheld SI engines (Classes III-V), and
exhaust and evaporative emission standards for all Marine SI engines.
Section 3.1 presents an overview of methodology used to develop the emission
inventories for the small nonroad and marine engines that are subject to the proposed
rulemaking. Section 3.2 identifies the specific modeling inputs that were used to develop the
baseline scenario emission inventories. The resulting baseline emission inventories are also
presented in that section. Section 3.3 then describes the contribution of the small nonroad and
Marine SI engines to national baseline inventories. Section 3.4 describes the development of the
controlled inventories, specifically the changes made to the baseline modeling inputs to
incorporate the new standards. The control inventories are also presented in this section.
Section 3.5 follows with the projected emission reductions resulting from the proposed rule.
Section 3.6 describes the emission inventories used in the air quality modeling described in
Chapter 2. This discussion includes a description of the changes in the inputs and resulting
emission inventories between the preliminary baseline and control scenarios used for the air
quality modeling and the more refined final baseline and control scenarios reflected in the actual
proposal.
In Sections 3.2, 3.4 and 3.5, the estimates of baseline, controlled, and emission reduction
inventories, respectively, for criteria pollutants from small nonroad and Marine SI engines are
reported for the 50-state geographic area (including the District of Columbia). These inventories
reflect the emissions from the engines subject to the proposed Phase 3 standards. As such, they
exclude the emissions from engines that are regulated by the State of California as provided for
by section 209 of the Clean Air Act.
More specifically, California is prevented from regulating nonroad engines with less than
175 horsepower that are used in farm and construction equipment. Therefore, those engines are
subject to federal regulation and included in our 50-state inventories. By contrast, we do not
include the emissions from California marine engines in our inventories. California has also
been granted a waiver under the Clean Air Act to regulate exhaust emissions form all Marine SI
engines and evaporative emissions from outboard and personal watercraft SI engines. That State
also has indicted its intent to adopt the proposed Phase III standards for evaporative emissions
from stern drive engines. Therefore, are excluded in our 50-state inventories.
In Section 3.3, 50-state inventories are used to compare the nationwide importance of
these sources to other source categories, i.e., stationary, area, and other mobile sources. Finally,
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Draft Regulatory Impact Analysis
Section 3.6 presents inventories for 37 of the most eastern states in the nation that were included
in the air quality modeling domain for this proposal. Unlike the 50-state inventories in the other
sections, these inventories include all small nonroad SI and marine engines. The 37-state
control scenarios assume federal standards apply only to those engines that are not subject to
California emission regulations as described earlier.
Inventories are generally presented for the following pollutants: exhaust and evaporative
total hydrocarbons (THC), oxides of nitrogen (NOX), particulate matter (PM25 and PM10), and
carbon monoxide (CO). The PM inventories include directly emitted PM only, although
secondary sulfates are taken into account in the air quality modeling as noted below. The
proposed requirements would also reduce hazardous air pollutants such as benzene,
formaldeyde, acetaldehyde, 1,3-butadiene, acrolein, napthalene, and 15 other compounds
grouped together as polycyclic organic matter (POM).
The hydrocarbon inventories in Sections 3.3 and 3.5 for the nationwide comparison and
air quality modeling, respectively, are presented as volatile organic compounds (VOC) rather
than THC. This is a broader class of hydrocarbon compounds that is important for air quality
modeling purposes. The additional compounds that comprise VOC are reactive oxygenated
species represented by aldehydes (RCHO) and alcohols (RCOH), and less reactive species
represented by methane (CH4) and ethane (CH3CH3).
Finally, none of the controlled inventory estimates include the potential uses of the
averaging, banking, and trading (ABT) program for engine manufacturers, since these are
flexibilities that would be difficult to predict and model. More information regarding these
provisions can be found in the preamble for this proposal that is published in the Federal
Register.
3.1 Overview of Small Nonroad and Marine SI Engine Emissions
Inventory Development
This section describes how the baseline emission inventories were modeled for the small
nonroad and Marine SI engines affected by the proposed rule. Section 3.1 focuses on exhaust
and evaporative hydrocarbons, and exhaust NOX PM, and CO.
The primary emission inventories associated with the small nonroad and Marine SI
engine proposed rule, which are summarized in Sections 3.2 through 3.5, were generated using a
modified version of our NONROAD2005 model. More specifically we started with the most
recent public version of the model, i.e., NONROAD2005a, which was released in February
2006. A copy of that model and the accompanying technical reports that detail of the modeling
inputs (e.g., populations, activity, etc.) are available in the docket for this proposal.1 They can
also be accessed on our website at: http://www.epa.gov/otaq/nonrdmdl.htm.
The NONROAD2005a model was modified to incorporate new emission test data and
other improvements for this rulemaking. This special version is named NONROAD2005c. A
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Emission Inventory
copy of the model and most of the accompanying documentation are available in the docket.2'3'4
The documentation for evaporative emission changes is in Chapter 5. The modifications we
made to NONROAD2005a to reflect the baseline and control scenarios related to the proposed
rule are fully described in Sections 3.2 and 3.4, respectively.
The nonroad model estimates emission inventories of important air emissions from a
diverse universe of nonroad equipment. The model's scope includes all off-highway sources
with the exception of locomotives, aircraft and commercial marine vessels. The model can
distinguish emissions on the basis of equipment type, horsepower, and technology group. For
the engines subject to the proposal, the nonroad model evaluates numerous equipment types with
each type containing multiple horsepower categories and technology groups. A central feature
of the model is the projection of future or past emissions between 1970 and 2050.
The chemical species NOx, PM, and CO are exhaust emissions, i.e., pollutants emitted
directly as exhaust from combustion of gasoline fuel in the engine. Hydrocarbon species, e.g.,
THC and VOC, consist of both exhaust and evaporative emissions. The exhaust component
represents hydrocarbons emitted as products of combustion, which can also include emissions
vented from the crankcase. The evaporative hydrocarbon component includes compounds from
unburned fuel that are emitted either while the engine being operated or when the equipment is
not in use. The various categories of evaporative emissions that are included in the nonroad
model are:
Diurnal. These emissions result from changes in temperature during the day. As the day
gets warmer there is a concomitant rise in the temperature of the liquid fuel in the fuel tank. This
causes the vapor pressure inside the tank to increase, forcing vaporized fuel to escape into the
atmosphere. For modeling purposes, this category also includes diffusion losses that come from
fuel vapor exiting the orifice of a vented fuel tank cap regardless of temperature.
Permeation. These emissions occur when fuel molecules transfuse through plastic or
rubber fuel-related components (fuel lines and fuel tanks) into the atmosphere.
Hot Soak. These emissions occur after the engine is shut off and the engine's residual
heat causes fuel vapors from the fuel tank or fuel metering device to be released into the
atmosphere.
Running Loss. Similar in form to diurnal losses, these emissions are caused from the
engine's heat during equipment operation.
Vapor Displacement or Refueling Loss. These are vapors displaced from the fuel tank
when liquid fuel is being added during a refueling event.
Liquid Spillage. This refers to the liquid fuel that is spilled when equipment is refueled
either from a portable fuel container or fuel pump, which subsequently evaporates into the
atmosphere.
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Draft Regulatory Impact Analysis
Equipment fueled by compressed natural gas, liquified petroleum gas, or diesel fuel are
assumed to have zero evaporative emissions. Consequently, all evaporative emissions are from
gasoline or gasoline blends, i.e., ethanol and gasoline.
The control scenario analyzed in Section 3.4 reflects the proposed standards for exhaust
hydrocarbons, CO, and NOx from small nonhandheld nonroad and Marine SI engines.1 New
standards to control evaporative emissions from hose permeation and tank permeation from these
engine classes and handheld equipment are also included. Further, the proposal also would
establish new standards for running loss and diffusion emissions from small nonhandheld
nonroad SI engines and diurnal emissions from Marine SI engines. Finally, we expect that the
technology necessary to achieve the proposed exhaust emission standards will indirectly lower
exhaust PM. All of these effects are reflected in the controlled emission inventories presented in
this chapter.
3.2 Baseline Emission Inventory Estimates
This section describes more specifically how we developed the baseline exhaust and
evaporative inventories for small nonroad and Marine SI engines. The resulting baseline
inventories are also presented. Section 3.2.1 provides this information for exhaust and
evaporative emissions.
The inventory estimates presented throughout this section include only equipment that
would be subject to the proposed standards. For small nonroad SI equipment, California's Air
Resources Board (ARB) has promulgated standards that are roughly equivalent in stringency
overall to our proposed national standards, although some of the specific requirements and test
procedures are different. However, the Clean Air Act prohibits California from regulating
engines used in farm and construction equipment with maximum power levels below 175 hp or
130 kW. Therefore, the requirements contained in this proposal for small nonroad SI engines
will apply in California to the above farm and construction equipment power levels. As a result,
these engines are included in the inventories presented in this chapter.
For Marine SI engines, ARB also has its own exhaust emission standards that are
roughly equivalent overall to our proposed national standards. In addition, ARB has stated its
intend to develop evaporative emissions standards for boats in California. Therefore, exhaust
and evaporative inventory estimates contained in this proposal are modeled for 49 states
(excluding California) for Marine SI engines.
3.2.1 Baseline Exhaust and Evaporative Emissions Estimates for THC, NOx, PM2 5, PM10,
and CO
The baseline exhaust and evaporative emission inventories for small nonroad and Marine
SI engines include the effects of all existing applicable federal emission standards. We
1 The CO standard applies to small nonhandheld SI engines used in auxiliary marine applications.
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Emission Inventory
generated these inventories by starting with the NONROAD2005a emissions model, which was
released to the public in February 2005. That model was then modified to incorporate new
emission test data and other improvements for this rulemaking. This special version of the
model is named NONROAD2005c. The modifications to the base model are described below.
3.2.1.1 Changes from NONROAD2005a to NONROAD2005c
As already mentioned, a number of improvements to the most publically available
nonroad emissions inventory model were made to develop the NONROAD2005c, which is used
in this proposed rulemaking. These revisions were based on recent testing programs, other
information, and model enhancements. The changes are summarized below for Small SI and
Marine SI engines. Many of the most important revisions are discussed in greater detail in the
following sections.
3.2.1.1.1 Revisions for Small SI Engines
The modifications that we made to the NONROAD2005a model for Small SI engines
that are most relevant to the proposal are summarized below:
1. Revised fuel tank and hose permeation emission factors;
2. Explicitly separated fuel tank diffusion losses to diurnal emission estimates;
3. Updated exhaust emission factors and deterioration rates, and technology-type
sales fractions for Phase 2 engines;
4. Adjusted equipment populations to properly account for the application of federal
emission requirements to engines in California; and
5. Added the ability to specifically model the effects of ethanol blends on fuel tank
and hose permeation.
3.2.1.1.2 Revisions for Recreation Marine SI Engines
The modifications that we made to the NONROAD2005a model for Marine SI engines
that are most relevant to the proposal are summarized below:
1. Revised brake-specific fuel consumption factors;
2. Revised PM emission factors for 2-stroke technology engines;
3. Revised fuel tank and hose permeation emission factors and temperature effects;
4. Updated modeling inputs for high performance sterndrive and inboard (SD/I)
engines; and
5. Added the ability to specifically model the effects of ethanol blends on fuel tank
and hose permeation.
3.2.1.2 Baseline Exhaust Emission Calculations
3.2.1.2.1 Small SI Exhaust Calculations
We revised the Phase 2 exhaust emission factors in the NONROAD2005a inventory
model to reflect new information and our better understanding of the in-use emissions of these
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Draft Regulatory Impact Analysis
engines, as discussed further below.
The nonroad model estimates exhaust emissions in a given year by applying an
appropriate emission factor based on the engines age or hours of use.5 This reflects the fact that
an engine's exhaust emissions performance degrades over its lifetime due to normal use or
misuse (i.e., tampering or neglect). More specifically, the emission factor is a combination of a
"zero-hour" emission level (ZHL) and a deterioration factor (DF). The ZHL represents the
emission rate for recently manufactured engines, i.e., engines with few operating hours. The DF
to the degree of emissions degradation per unit of activity. Nonroad engine activity is expressed
in terms of hours of use or fraction of its median life. This later term refers to the age at which
50 percent of the engines sold in a given year ceased to function and have been scrapped. The
following formula describes the basic form of the calculation:
EFaged = ZHLxDF
where: EFaged is the emission factor for an aged engine
ZML is the zero hour emission factor for a new engine
DF is the deterioration factor
The form of the DF for nonroad SI engines is as follows:
DF = 1 + A x (Age Factor) for Age Factor < 1
DF = 1 + A for Age Factor > 1
where: Age Factor = [Cumulative Hours x Load Factor]
Median Life at Full Load, in Hours
A, = constants for a given technology type; b < 1.
The constants A and b can be varied to approximate a wide range of deterioration
patterns. "A" can be varied to reflect differences in maximum deterioration. For example,
setting A equal to 2.0 would result in emissions at the engine's median life being three times the
emissions when new. The shape of the deterioration function is determined by the second
constant, b. This constant can be set at any level between zero and 1.0; currently, the
NONROAD model sets b equal to either 0.5 or 1.0. The first case results in a curvilinear
deterioration rate in which most of the deterioration occurs in the early part of an engine's life.
The second case results in a linear deterioration pattern in which the rate of deterioration is
constant throughout the median life of an engine. In both cases, we previously decided to cap
deterioration at the end of an engine's median life, under the assumption that an engine can only
deteriorate to a certain point beyond which it becomes inoperable. For spark ignition engines at
or below 25 horsepower, which are the subject of this proposal, the nonroad model sets the
constant b equal to 0.5. The emission factor inputs for Phase 2 small nonroad SI engines used in
this analysis are shown in Table 3.2-1
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Emission Inventory
Table 3.2-1: Phase 2 Modeling Emission Factors for Small SI Engines(g/kW-hr)
Class/
Tprhnnlnpy
Class I - SV
Class I - OHV
Class II
HCZML
10.30
8.73
5.58
HC "A"
1.753
1.753
1.095
NOxZML
2.57
3.28
3.71
NOx "A"
0.000
0.000
0.000
COZML
386.53
392.93
472.80
CO "A"
0.070
0.070
0.080
PM10
7MT,*
0.35
0.05
0.08
PM10
"A"*
1.753
1.753
1.095
: The nonroad model calculates PM2.5 as 92 percent of PM10.
Some of the values shown in Table 3.2-1 have been updated from the NONROAD2005a
inventory model based on data collected by EPA on in-use engines as well as
manufacturer-supplied certification data. The ZHL emission factors for Class I engines were
updated based on testing performed by EPA on 16 in-use walk-behind lawnmowers. The Class I
side-valve engine A values were revised to be the same as the Class I overhead engine A values
based on the same in-use testing of lawnmowers which showed similar in-use deterioration
characteristics between overhead valve and sidevalve Class I engines. The Class I and Class II
engine A values for CO emissions were revised to better reflect the level of deterioration seen in
both the in-use lawnmower testing noted above as well as certification data provided by
manufacturers to EPA. Finally, based on data collected from another test program of in-use
lawnmowers, the assumption that there was no deterioration of Class I and II emissions after the
median life was reached was revised to reflect further continued emissions deterioration after
that point.
Also, the model was modified to acknowledge the continued use of side-valve engine
designs in Class I nonhandheld engines meeting Phase 2 standards. In the rulemaking that
established those regulatory requirements, side-valve technology was assumed to be superceded
by overhead valve designs and was modeled accordingly. In reality, side-valve technology has
continued to be used in small nonroad SI engines. The resulting technology mixture is shown in
Table 3.2-2. The estimated sales fractions by engine class and technology are based on sales
information provided by engine manufacturers to EPA for the 2005 model year. A full
description of the emission modeling information for Phase 2 engines and the basis for the
estimates can be found in the docket for this rule.
Table 3.2-2: Phase 3 Small Nonroad SI Engine Technology Classes
Engine Class
Class I
Class I
Class II
Technology Class
Side Valve
Overhead Valve
Overhead Valve
Percent Sales (%)
60
40
100
3.2.1.2.2 Marine SI Exhaust Calculations
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Draft Regulatory Impact Analysis
The NONROAD2005a model included a number of recent updates to the emission rates
and technology mix of Marine SI engines.6 These updates were largely based on data submitted
to EPA by marine engine manufacturers as part of the certification process and on new test data
collected by EPA.7 However, NONROAD2005a does not include high-performance SD/I
marine engines. High-performance marine engines are niche product and were not included in
the data set used to develop the engine populations for the NONROAD2005a model.
Manufacturers have recently commented that approximately 1,500 high-performance
engines are produced in the U.S. per year. These engines range from 500 to 1500 horsepower
and are used in both racing and non-racing applications. Based on conversations with individual
high-performance engine manufacturers, we estimate that about two thirds of these engines are
sold for use in the U.S. with an average power of about 650 horsepower. These engines are
designed to sacrifice service life for power, but with rebuilds, generally are used for 7-8 years
(we use 8 years for our modeling). Based on these estimates and the growth rate in the
NONROAD2005a model, we estimate a 1998 population of SD/I engines >600 horsepower of
7500 units. One manufacturer stated that they performed a survey on the annual use of these
engines for warranty purposes and the result was an average annual use of about 30 hours per
year. We also updated the baseline emission factors for high performance marine engines based
on the emission data presented in Chapter 4. Note that no changes were made to the PM
emission factors because no new data was available. Table 3.2-3 presents the updated emission
factors for high-performance SD/I marine engines.
Table 3.2-3: Emission Factors for High-Performance Marine Engines [g/kW-hr]
Pollutant
HC
CO
NOx
PM
BSFC
Carbureted Engines
(MS4C, Bin 12)
13.8
253
8.4
0.08
400
Fuel-Injected Engines
(MS4D, Bin 12)
13.8
207
6.8
0.08
362
3.2.1.3 Baseline Evaporative Emission Calculations
Chapter 5 presents a great deal of information on evaporative emission rates from fuel
systems used in nonroad equipment. Much of this information was incorporated into the
NONROAD2005a model.8 However, we have continued to collect evaporative emission data
and incorporate the new information into our evaporative emission inventory calculations.
These updates are described below.
3.2.1.3.1 Fuel Ethanol Content
Currently, about 30 percent of fuel sold in the U.S. contains ethanol. With the recent
establishment of the Energy Policy Act of 2005,9 this percentage is expected to increase. The
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Emission Inventory
significance of the use of ethanol in fuel, for the inventory calculations, is that ethanol in fuel can
affect the evaporative emissions from nonroad equipment. Fuel blends containing ethanol
typically increase the permeation rate for most materials used in gasoline fuel systems. This is
discussed in more detail below.
Title XV, section 1501, of the Energy Policy Act requires that the total volume of
renewable fuel increase from 4.0 to 7.5 billion gallons per year from 2006 to 2012, and the
Energy Information Administration (EIA) predicts that production will actually reach 9.6 billion
gallons per year by then. Based on these figures and projected gasoline sales from the Energy
Information Administration,10'11'12 we estimate that about two-thirds of gasoline sold in 2012 and
later will contain ethanol. Table 3.2-4 presents our estimates for ethanol blended fuels into the
future. The blend market shares shown in the last column of this table assume 10 percent for
ethanol content of blended gasoline in all areas except California, where it is 5.7 volume percent.
Table 3.2-4: Estimated Fraction of Gasoline Containing Ethanol
Calendar Year
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
U.S. Gasoline Sales
[109gal.]
129.9
132.0
135.6
137.0
139.6
139.9
141.3
143.0
145.4
148.1
150.9
153.3
155.6
U.S. Ethanol Sales
[109gal.]
1.6
1.8
2.1
2.8
3.4
3.8
4.1
5.2
6.0
6.9
7.9
8.8
9.6
Fraction of Gas with
Ethanol
13.5%
14.5%
17.0%
22.2%
26.3%
29.7%
31.6%
39.2%
44.9%
50.4%
56.4%
62.2%
67.1%
ethanol fraction projected to be constant after last year of Energy Policy Act phase-in (2012)
3.2.1.3.2 Hose Permeation
We developed hose permeation emission factors based on the permeation data and hose
requirements presented in Chapter 5. Because permeation is a function of surface area and
because hose lengths and inner diameters are defining parameters, hose permeation rates are
based on g/m2/day. These emission factors incorporate a more complete set of data than those in
the NONROAD2005a model. In addition, distinctions are now made between permeation rates
for liquid fuel versus fuel vapor exposure and between permeation rates for gasoline versus
ethanol-blend fuels. The updated hose emission factors are discussed below and presented in
Table 3.2-5.
Fuel hoses in Small SI applications vary greatly in construction depending on the
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Draft Regulatory Impact Analysis
individual specifications of the engine and equipment manufacturers. However most fuel hose
used on non-handheld equipment meets the SAE J30 R7 hose requirements which includes a
permeation requirement of 550 g/m2/day on Fuel C at 23°C.13 Chapter 5 presents data on several
hose constructions that range from 190 to 450 g/m2/day on Fuel C. As discussed in Chapter 5,
permeation is typically lower on gasoline than on Fuel C. At the same time, blending ethanol
into the fuel increases permeation. Based on data presented in Chapter 5, we estimate that non-
handheld fuel hose permeation rates range from 27 to 180 g/m2/day on gasoline and 80-309
g/m2/day on gasoline blended with 10 percent ethanol (E10). Of the data presented in Chapter 5,
the lowest two permeation rates for SAE J30 R7 hose were from an unknown fuel hose
construction and from a hose (used in some Small SI applications) that was specially constructed
of fuel resistant materials to facilitate painting. Dropping the unknown hose construction (which
is not known to be used in Small SI applications), we get average permeation rates of 122
g/m2/day on gasoline and 222 g/m2/day on E10 at 23 °C.
Chapter 5 also presents permeation data on nine samples of fuel lines used in handheld
equipment tested using E10 fuel. The permeation rates for these samples ranged from 165 to 455
g/m2/day at 23°C with an average of 255 g/m2/day. All of the hose samples, except one were
made of NBR rubber, with the exception being a NBR/PVC blend. To determine an emission
factor for handheld fuel lines on gasoline, we used the ratio of permeation rates for NBR rubber
samples on E10 versus gasoline. The resulting permeation rate for handheld hose on gasoline
was estimated to be 140 g/m2/day at 23 °C.
Fuel hose for portable marine fuel tanks is not subject to any established recommended
practice. For this reason, we consider fuel hose used on portable marine fuel tanks to be
equivalent to the hose used in Small SI applications. The supply hose for each portable marine
fuel tank is modeled to include a primer bulb with the same permeation rate as the hose.
Recommended practices for marine hose on SD/I vessels include a permeation rate of
100 g/m2/day on Fuel C and 300 g/m2/day on fuel CM15 (15 percent methanol).14'15
Accordingly, these vessels have fuel hose with lower permeation. Rather than using the
recommended permeation rate limits for this hose, we base the permeation emission factors for
this hose on the data presented in Chapter 5 on gasoline with ethanol which is more
representative of in-use fuels. Chapter 5 also includes data on commercially available low
permeation fuel hose which is used by some manufacturers. However, we do not include this in
the baseline emission factor calculation because its use is primarily in anticipation of upcoming
permeation standards and would therefore not be expected to remain in the baseline without
enactment of this proposed rule.
For other vessels with installed fuel tanks (OB and PWC), we based the permeation
emission factors on the test data in Chapter 5 on marine hose not certified to Coast Guard Class I
requirements.
The Coast Guard specifications for fill neck hose call for a permeation limit of 300
g/m2/day on Fuel C and 600 on Fuel CM15. However, fill neck hose are not usually exposed to
liquid fuel. Therefore, we used the vapor line data presented in Chapter 5 for both fill neck and
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Emission Inventory
vent line permeation rates. Hose permeation rates for both gasoline and E10 are presented in
Table3.2.-5.
Table 3.2-5: Hose Permeation Emission Factors at 23°C [g/ni2/day]
Hose Type
Handheld equipment fuel hose
Non-handheld equipment fuel hose
Portable fuel tank supply hose*
Installed system OB/PWC fuel lines
Installed system SD/I fuel lines
Fill necks and vent lines (vapor exposure)
Gasoline
140
122
122
42
22
2.5
E10
255
222
222
125
40
4.9
* this permeation rate is used for primer bulbs as well
The above permeation rates do not include any effects of deterioration. Over time, the
fuel can draw some of the plasticizers out of the rubber in the hose, making it more brittle and
subject to cracking. This is especially true for higher permeation fuel hoses which are generally
less fuel resistant. Exposure to ozone over time can also deteriorate the hose. This deterioration
would presumably increase the permeation rate over time. However, we do not have any data to
quantify this effect and are not including deterioration in this analysis at this time. Lower
permeation fuel hose, such as that designed to meet the proposed standard would likely have
much lower deterioration due to the use of more fuel resistant materials. Therefore this analysis
may underestimate the inventory and benefits associated with the proposed fuel permeation
standards.
3.2.1.3.3 Hose Lengths
The hose lengths used in NONROAD2005a are based primarily on confidential
information supplied by equipment manufacturers. Hose lengths for handheld equipment are
based on survey data provided by the Outdoor Power Equipment Institute.16 Recently, we
received comment from a boatbuilder using outboard motors that the hose lengths in our
calculations were too short.17 Because our existing data set did not include outboard boats with
installed fuel tanks, we updated the hose lengths for these vessels based on the data supplied by
this boat builder. In addition, the vent line lengths in the NONROAD2005a were divided by two
to account for a vapor gradient throughout the fuel line caused by diurnal breathing and
diffusion. This factor has been removed in lieu of the new emission factors for vent lines based
on vapor exposure. Table 3.2-6 presents the updated hose lengths for outboard boats with
installed fuel tanks.
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Draft Regulatory Impact Analysis
Table 3.2-6: Updated Hose Lengths for Outboard Boats with Installed Fuel Systems
Engine Power
Category
18.7-29.8 kW
29.9-37.3 kW
37.4-74.6 kW
74.7-130.5 kW
130.6+ kW
Fill Neck
Length [m]
1.8
2.4
3.1
3.7
4.3
Fuel Supply Hose
Length [m]
1.8
2.4
3.1
3.7
4.3
Vent Hose
Length [m]
1.5
1.8
2.1
2.4
2.7
3.2.1.3.4 Tank Permeation
For fuel tanks, the NONROAD2005a model does not include a fuel ethanol effect on
permeation. Data in Chapter 5 suggest that even polyethylene fuel tanks see a small increase in
permeation on E10 compared to gasoline. This increase is much larger for nylon fuel tanks like
those used in handheld equipment with structurally-integrated fuel tanks. Table 3.2-7 presents
the updated emission factors on E10 fuel and compares them to the emission factors based on
gasoline permeation rates. The primary difference between the permeation rates for installed
marine tanks, compared to smaller HDPE fuel tanks, is largely due to the wall thickness of the
different constructions rather than material permeation properties. Permeation rate is a function
of wall thickness, so as tank thickness doubles, permeation rate halves. The model considers
permeation from metal fuel tanks to be zero.
Table 3.2-7: Tank Permeation Emission Factors at 29°C [g/m2/day]
Tank Type
Nylon handheld fuel tanks
Small SI HDPE <0.25 gallons
Small SI HDPE >0.25 gallons
Portable and PWC HDPE fuel tanks
Installed non-metal marine fuel tanks
Metal tanks
Gasoline
1.25
6.5
9.7
9.9
8.0
0
E10
2.5
7.2
10.7
10.9
8.8
0
3.2.1.3.5 Diffusion
The NONROAD2005a model includes an adjustment factor to diurnal emissions to
account for diffusion. The data used to create this adjustment factor is included in Chapter 5.
This adjustment factor is applied to all Small SI equipment in the NONROAD2005a model.
However, we believe that handheld equipment are all produced with either sealed fuel tanks or
slosh/spill resistant fuel caps. Therefore, we do not include diffusion emissions for handheld
equipment in this analysis.
3-12
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Emission Inventory
3.2.1.3.6 Modeling of Nonlinear Ethanol Blend Permeation Effects
Based on the limited available test data it appears that the effect of alcohol-gasoline
blends on permeation is nonlinear, tending to increase permeation at lower alcohol
concentrations up to about 20 percent ethanol, but then decreasing permeation at higher alcohol
• IS
concentrations.
Starting with the zero and 10 percent ethanol points described above, a simple
exponential curve was selected to connect the zero and 10 percent points continuing up to the 20
percent ethanol level. Then to get a nonlinear decreasing curve above 20 percent a simple
decreasing exponential curve was used. Since effects above 85 percent are especially uncertain,
and no such fuels are foreseen for use in nonroad equipment, the effect above 85 percent was set
equal to the E85 effect. The equations used are shown here, and an example curve based on
these equations is shown in Figure 3.2-1.
3-13
-------
Draft Regulatory Impact Analysis
Hose and Tank Permeation for 0-20 percent ethanol volume percent:
Permeation EF = GasEF + GasEF x (ElOfac - 1) x [ (EthVfrac / 0.10) A 0.4 ]
Hose and Tank Permeation for ethanol volume percent greater than 20 percent:
Permeation EF = GasEF x { 1 + (ElOfac - 1) x [ (20 / 10) A 0.4 ] }
x { 1 - [ (MIN(EthVfrac, 0.85) - 0.20 ) / 0.80 ] A (1 / 0.4 ) }
where:
Permeation EF = Permeation emission factor for modeled fuel (grams per meter2 per day)
GasEF = Gasoline hose permeation emission factor from input EF data files (grams per
meter2 per day)
ElOfac = permeation emission adjustment factor for E10 relative to gasoline. This is the
ratio of the E10 to gasoline permeation emission factors (unitless)
EthVfrac = Volume fraction ethanol in the fuel being modeled. El0 = 0.10
0.4 = exponent chosen to yield a reasonable shape of curve.
Figure 3.2-1: Ethanol Blend Hose Permeation Example Curve
300.0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Ethanol Volume Fraction
Note that all ethanol blends currently modeled with NONROAD or NMIM are less than
or equal to E10, so no parts of this curve above E10 are used. Also note that the value of ElOfac
used in the modeling of the control case is 2.0 for all the tank and hose permeation sources listed
above in Tables 3.2-6 and 3.2-7.
3-14
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Emission Inventory
3.2.1.3.7 Modeling Effect ofEthanol Blend Market Share on Permeation
The effect of ethanol blend market share is modeled linearly. In most areas the ethanol
blend market share is either zero or 100 percent, but in areas where it is between those two
market shares, or when doing a nationwide model run, the effect is calculated as a simple
proportion. For instance a 30 percent market share of E10 would be modeled using a permeation
rate 30 percent of the way between the EO permeation rate and the E10 permeation rate.
3.2.1.4 Baseline Exhaust and Evaporative Inventory Results for THC, NOx, PM2 5,
PM10, and CO
Table 3.2-8 presents the 50-state baseline emission inventories, respectively, for small
nonroad SI engines. Table 3.2-9 provides the same information for Marine SI engines.
3-15
-------
Draft Regulatory Impact Analysis
Table 3.2-8: Baseline 50-State Annual Exhaust and Evaporative Emissions for
Small Nonroad Spark-Ignition Engines (short tons)
Year
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
9040
THC
1,099,402
1,074,137
1,039,522
978,760
905,814
849,619
794,827
748,034
715,943
700,482
698,481
700,981
706,486
714,968
724,695
735,292
746,447
758,021
769,929
781,985
794,072
806,192
818,336
830,496
842,686
855,022
867,389
879,769
892,157
904,553
916,953
929,357
941,764
954,175
966,587
979,003
991,420
1,003,840
1,016,261
1,028,684
NOx
101,928
101,261
99,649
97,929
95,779
94,550
92,988
90,638
89,272
88,968
89,543
90,440
91,607
92,973
94,432
95,959
97,519
99,101
100,700
102,310
103,922
105,533
107,145
108,759
110,379
112,019
113,666
115,314
116,964
118,615
120,267
121,919
123,571
125,223
126,875
128,527
130,179
131,832
133,484
135,136
PM2.5
23,163
23,382
23,480
23,483
23,417
23,498
23,804
24,335
24,882
25,402
25,888
26,364
26,832
27,291
27,747
28,202
28,655
29,107
29,558
30,009
30,460
30,911
31,362
31,813
32,265
32,718
33,173
33,627
34,081
34,535
34,990
35,444
35,898
36,353
36,807
37,261
37,716
38,170
38,625
39,079
PM10
25,177
25,416
25,522
25,525
25,453
25,541
25,874
26,451
27,045
27,611
28,139
28,657
29,165
29,664
30,160
30,654
31,146
31,638
32,128
32,618
33,109
33,599
34,089
34,579
35,070
35,563
36,057
36,551
37,045
37,538
38,032
38,526
39,020
39,514
40,008
40,502
40,995
41,489
41,983
42,477
CO
16,108,103
15,560,774
14,941,296
14,382,759
13,784,367
13,369,719
12,919,586
12,285,206
11,775,265
11,492,162
11,426,366
11,438,836
11,517,029
11,645,064
11,797,078
11,965,466
12,143,564
12,328,523
12,519,136
12,712,775
12,907,487
13,102,999
13,299,184
13,495,942
13,693,641
13,893,823
14,094,990
14,296,561
14,498,417
14,700,521
14,902,797
15,105,180
15,307,643
15,510,182
15,712,789
15,915,457
16,118,191
16,320,977
16,523,816
16.726.708
3-16
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Emission Inventory
Table 3.2-9: Baseline 50-State Annual Exhaust and Evaporative Emissions for
Marine Spark-Ignition Engines (Short Tons)
Year THC NOx PM2.5 PM10 CO
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
935,494
909,607
877,441
841,151
801,985
762,092
724,443
687,350
651,744
618,843
588,283
561,699
538,510
518,615
502,307
488,502
477,287
469,041
462,146
457,338
453,687
451,360
449,882
449,089
449,054
449,611
450,640
451,987
453,610
455,480
457,536
459,725
462,071
464,529
467,079
469,685
472,348
475,055
477,796
480.560
41,514
43,401
45,661
48,164
50,675
53,207
55,750
58,296
60,797
63,228
65,613
67,843
69,883
71,789
73,583
75,245
76,781
78,169
79,469
80,655
81,768
82,796
83,756
84,663
85,517
86,327
87,096
87,828
88,537
89,225
89,896
90,554
91,197
91,828
92,448
93,060
93,664
94,261
94,853
95.440
15,625
15,092
14,417
13,679
12,886
12,090
11,311
10,553
9,824
9,149
8,525
7,983
7,534
7,144
6,823
6,549
6,324
6,156
6,012
5,908
5,826
5,768
5,726
5,696
5,680
5,675
5,678
5,687
5,701
5,719
5,741
5,765
5,792
5,821
5,851
5,883
5,915
5,948
5,982
6.016
16,984
16,404
15,670
14,869
14,007
13,142
12,295
11,470
10,678
9,945
9,266
8,678
8,189
7,766
7,416
7,118
6,874
6,691
6,535
6,422
6,333
6,270
6,224
6,191
6,174
6,168
6,172
6,182
6,197
6,217
6,240
6,266
6,296
6,327
6,360
6,394
6,429
6,465
6,502
6.539
2,584,786
2,552,368
2,510,927
2,469,934
2,423,497
2,375,768
2,328,182
2,280,928
2,235,187
2,191,484
2,149,407
2,112,511
2,081,945
2,054,769
2,031,684
2,011,569
1,995,319
1,983,611
1,974,297
1,968,663
1,965,024
1,963,888
1,964,657
1,967,014
1,971,025
1,976,557
1,983,392
1,991,331
1,999,984
2,009,248
2,019,028
2,029,227
2,039,870
2,050,883
2,062,245
2,073,873
2,085,737
2,097,797
2,110,011
2.122.336
3-17
-------
Draft Regulatory Impact Analysis
3.2.2 Baseline Hazardous Air Pollutant Estimates
The analysis of toxic air pollutants from small nonroad and Marine SI engines focuses
on seven major pollutants: benzene, formaldehyde, acetaldehyde, 1,3-butadiene, acrolein,
naphthalene, and 15 other compounds grouped together as poly cyclic organic matter (POM) for
this analysis.2 All of these compounds, except acetaldehyde, were identified as national or
regional cancer or noncancer "risk" drivers in the 1999 National Scale Air Toxics Assessment
(NATA)19 and have significant inventory contributions from mobile sources. That is, for a
significant portion of the population, these compounds pose a significant portion of the total
cancer or noncancer risk from breathing outdoor air toxics. The health effects of these hazardous
pollutants are specifically discussed in Section 2.3. Many of these compounds are also part of
the THC inventories. An exception is formaldehyde, which is not measured by the analytic
technique used to measure THC, and part of the mass of other aldehydes as well.
However, all are included in the VOC inventories presented in this chapter.
The baseline inventories for each of the toxic air pollutants described above are based on
the work performed for EPA's mobile source air toxic (MSAT) final rulemaking.20 The
hazardous air pollutant inventories for all nonroad equipment except aircraft, locomotives, and
commercial marine vessels in MS AT were developed using EPA's National Mobile Inventory
Model (NMIM). This model is an analytical framework that links a county-level database to our
highway and nonroad models and collates the output into a single database table. The resulting
estimates for small nonroad and Marine SI engines account for local differences in fuel
characteristics and temperatures.
The modeling results reflect the future use of renewable fuels as specified in the Energy
Policy Act of 2005. Emissions were modeled for each county in the continental U.S. for 1999,
2010, 2015, 2020, and 2030. For this proposal, a special NMIM simulation was also performed
using the MS AT methodology for 2001 (our base year). The analysis for this additional year is
also included in the MSAT documentation for completeness.
To estimate the baseline air toxics inventories for this proposal, we started with the
MSAT baseline case (no air toxics control) results for the Source Category Codes (SCCs) that
contain the affected small nonroad and Marine SI engines.3 Those inventories were produced by
the NMIM model using NONROAD2005a (the latest public release), so they do not reflect the
emission modeling improvements we made for the proposed rule. Therefore, we corrected the
MSAT air toxics inventories to mirror the results from our improved NONROAD2005c model.
2 The 15 POMs summarized in this chapter are acenaphthene, acenapthylene, anthracene,
benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylkene, beno(k)fluoranthene, chrysene,
dibenzo(a,h)anthracene,fluoranthene, fluorene, ideno(l,2,3,c,c)-pyrene, phenanthrene, andpyrene.
3 MSAT controls only affect the benzene content of nonroad gasoline fuel. Therefore, if the MSAT control
case was used, only the benzene inventory for the nonroad engines affected by this proposal would be significantly
affected.
3-18
-------
Emission Inventory
This adjustment was done to avoid the need to run the NMEVI/MSAT model, which is quite
resource intensive, using the new NONROAD2005c model.
The hazardous air pollutant inventory for each exhaust and evaporative gaseous
hydrocarbon species is estimated in NMEVI as a fraction of VOC emissions, except for POMs,
which are found in both the gas and particle phase. For each POM hydrocarbon species, the
toxics inventory is estimated as a ratio to PM. Therefore, in order to correct the MSAT results to
mirror the improved model results, we multiplied each MSAT hazardous air pollutant inventory
for the applicable nonroad SCCs by the ratio of the VOC or PM emission results, as appropriate,
from the new NONROAD2005c model to the respective NMIM NONROAD2005a model
results.
Tables 3.2-10 presents the 50-state baseline inventories, respectively, for toxic air
emissions from small nonroad SI engines. Tables 3.2-11 provides the same information for
Marine SI engines.
Table 3.2-10: Baseline 50-State Air Toxic Emissions for
Small Nonroad Spark-Ignition Engines (short tons)
Year
2001
2020
2030
Benzene
33,534
22,923
26,502
1,3
Butadiene
5,165
3,169
3,663
Formalde-
hyde
8,035
5,182
5,991
Acetalde-
hyde
2,826
2,429
2,805
Acrolein
462
270
312
Napthalene
418
409
475
POM
93
107
123
Table 3.2-11: Baseline 50-State Air Toxic Emissions for
Marine Spark-Ignition Engines (short tons)
Year
2001
2020
2030
Benzene
21,590
9,144
9,073
1,3
Butadiene
1,790
694
670
Formalde-
hyde
1,846
606
583
Acetalde-
hyde
1,354
666
649
Acrolein
179
47
45
Napthalene
32
32
34
POM
30
15
15
3.3 Contribution of Small Nonroad and Marine SI Engines to National
Emissions Inventories
This section describes the nationwide contribution of small nonroad and Marine SI
engines to the emissions of other source categories. Information is presented for the pollutants
that are directly controlled by the proposed standards, i.e., VOC, NOX, and CO, and those that are
indirectly reduced by some of the requisite control technology, i.e., PM25 and PM10. The VOC
3-19
-------
Draft Regulatory Impact Analysis
inventories includes both exhaust and evaporative hydrocarbon emissions.
3.3.1 National Emission Inventory Development
The national inventories are presented for 2001, 2015, and 2020 for the contiguous 48-
states of the U.S. and the District of Columbia.21 The stationary, area, motorcycle, aircraft,
locomotive, commercial marine inventories were taken directly from EPA's most recent air
quality modeling for the PM NAAQS. The gaseous emission inventories for highway diesel
vehicles and the 2001 calendar year PM emission estimates for highway diesel vehicles were
also taken directly from that work. The emission inventories for on highway gasoline vehicles
were taken from work performed for our Mobile Source Air Toxics (MSAT) rulemaking
analysis. These inventories account for the future use of renewable fuels as required by the
Energy Policy Act of 2005. Finally, the nonroad engine baseline inventories were estimated
using the modified version of NONROAD2005a that was developed for this proposal, as
discussed further in Section 3.2.1.
3.3.1.1 VOC Emissions Contribution
Table 3.3-1 provides the contribution of small nonroad SI engines, Marine SI engines
and other source categories to total VOC emissions. The emissions from nonroad Small SI
(<19kW) and Marine SI engines are 28 percent of the mobile source inventory and 13 percent of
the total manmade VOC emissions in 2001. These percentages decrease slightly to 27 percent
and 10 percent, respectively, by 2020.
3.3.1.2 NOx Emissions Contribution
Table 3.3-2 provides the contribution of nonroad small nonroad SI engines, Marine SI
engines and other source categories to total NOx emissions. The emissions from small nonroad
and Marine SI engines are 1 percent of the mobile source inventory and 1 percent of the total
manmade NOx emissions in 2001. These percentages increase to 4 percent and 2 percent,
respectively, by 2020.
3.3.1.3 PM Emissions Contribution
Table 3.3-3 and 3.3-4 provide the contribution of small nonroad SI engines, Marine SI
engines and other source categories to total PM2 5 and PM10 emissions, respectively. Both
particle size categories from small nonroad and Marine SI engines are about 9 percent of the
mobile source inventory and approximately 2 percent of the total manmade PM25 emissions in
2001. These percentages stay about the same at about 10 percent and 2 percent, respectively, by
2020.
3.3.1.4 CO Emissions Contribution
Table 3.3-5 provides the contribution of small nonroad SI engines, Marine SI engines
and other source categories to total CO emissions. The emissions from small nonroad and
3-20
-------
Emission Inventory
Marine SI engines are 24 percent of the mobile source inventory and 22 percent of the total
manmade CO emissions in 2001. These percentages decrease to 22 percent and increase to 27
percent, respectively, by 2020.
3-21
-------
Table 3.3-1: 50-State Annual VOC Baseline Emission Levels for
Mobile and Other Source Categories
Category
Small Handheld Nonroad SI
Small Nonhandheld Nonroad SI
Marine SI
SI Recreational Vehicles
Large Nonroad SI (>25hp)
Portable Fuel Containers*
Land-Based Nonroad Diesel
Marine Diesel
Commercial Marine
Locomotive
Aircraft
Total Off Highway
Total Highway
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources
2OO1
short tons
503,772
699,516
1,035,768
497,207
132,820
244,545
188,884
1,472
33,577
39,279
22,084
3,398,924
4,540,133
7,939,058
9,692,344
17.631.402
%of
mobile
source
6.3%
8.8%
13.0%
6.3%
1.7%
3.1%
2.4%
0.02%
0.42%
0.49%
0.28%
42.8%
57.2%
100.0%
-
-
% of total
2.9%
4.0%
5.9%
2.8%
0.75%
1.39%
1.07%
0.01%
0.19%
0.22%
0.13%
19.3%
25.8%
45.0%
55.0%
100.0%
2015
short tons
204,425
582,107
552,888
593,624
20,012
238,055
95,934
1,636
39,956
35,423
25,426
2,389,485
2,865,967
5,255,453
8,519,026
13.774.479
%of
mobile
source
3.9%
11.1%
10.5%
11.3%
0.4%
4.5%
1.8%
0.03%
0.76%
0.67%
0.48%
45.5%
54.5%
100.0%
-
-
% of total
1.5%
4.2%
4.0%
4.3%
0.15%
1.73%
0.70%
0.01%
0.29%
0.26%
0.18%
17.3%
20.8%
38.2%
61.8%
100.0%
2020
short tons
221,027
627,909
502,803
443,407
12,220
254,479
76,047
1,623
43,876
34,407
27,644
2,245,442
2,769,812
5,015,254
8,475,443
13.490.697
%of
mobile
source
4.4%
12.5%
10.0%
8.8%
0.2%
5.1%
1.5%
0.03%
0.87%
0.69%
0.55%
44.8%
55.2%
100.0%
-
-
% of total
1.60/
4.1%
3.7%
3.3%
0.09%
1.890/
0.56%
0.0 1%
0.33%
0.26%
0.20%
16.6%
20.5%
31.2%
62.80/
100.0%
-------
Table 3.3-2: 50-State Annual NOx Baseline Emission Levels
for Mobile and Other Source Categories
Category
Small Handheld Nonroad SI
Small Nonhandheld Nonroad SI
Marine SI
SI Recreational Vehicles
Large Nonroad SI (>25hp)
Land-Based Nonroad Diesel
Marine Diesel
Commercial Marine
Locomotive
Aircraft
Total Off Highway
Total Highway
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources
2001
short tons
2,678
111,641
44,732
5,948
325,636
1,548,236
39,301
930,886
999,455
83,764
4,092,277
8,105,316
12,197,593
9,355,659
21 553 252
%of
mobile
source
0.0%
0.9%
0.4%
0.0%
2.7%
12.7%
0.32%
7.63%
8.19%
0.69%
33.5%
66.5%
100.0%
-
-
% of total
0.0%
0.5%
0.2%
0.0%
1.51%
7.18%
0.18%
4.32%
4.64%
0.39%
19.0%
37.6%
56.6%
43.4%
100 0%
2015
short tons
3,647
102,382
79,288
15,287
63,747
969,065
47,282
953,398
646,647
95,330
2,976,071
2,811,495
5,787,566
6,107,354
11 894919
%of
mobile
source
0.1%
1.8%
1.4%
0.3%
1.1%
16.7%
0.82%
16.47%
11.17%
1.65%
51.4%
48.6%
100.0%
-
-
% of total
0.0%
0.9%
0.7%
0.1%
0.54%
8.15%
0.40%
8.02%
5.44%
0.80%
25.0%
23.6%
48.7%
51.3%
100 0%
2020
short tons
3,945
110,936
86,908
18,224
46,888
678,377
48,557
989,930
627,659
105,133
2,716,559
2,008,237
4,724,796
6,111,866
10 836 662
%of
mobile
source
0.1%
2.3%
1.8%
0.4%
1.0%
14.4%
1.03%
20.95%
13.28%
2.23%
57.5%
42.5%
100.0%
-
-
% of total
0.0%
1.0%
0.8%
0.2%
0.43%
6.26%
0.45%
9.14%
5.79%
0.97%
25.1%
18.5%
43.6%
56.4%
100 0%
-------
Table 3.3-3: 50-State Annual PM2 5 Baseline Emission Levels
for Mobile and Other Source Categories
Category
Small Handheld Nonroad SI
Small Nonhandheld Nonroad SI
Marine SI
SI Recreational Vehicles
Large Nonroad SI (>25hp)
Land-Based Nonroad Diesel
Marine Diesel
Commercial Marine
Locomotive
Aircraft
Total Off Highway
Total Highway
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources
2001
short tons
20,587
4,879
16,837
12,301
1,610
164,180
1,066
39,829
24,418
5,664
291,371
160,229
451,600
1,963,264
2.414.864
%of
mobile
source
4.6%
1.1%
3.7%
2.7%
0.4%
36.4%
0.24%
8.82%
5.41%
1.25%
64.5%
35.5%
100.0%
-
-
% of total
0.9%
0.2%
0.7%
0.5%
0.07%
6.80%
0.04%
1.65%
1.01%
0.23%
12.1%
6.6%
18.7%
81.3%
100.0%
2015
short tons
24,015
6,403
7,352
15,864
2,207
75,788
774
46,567
16,967
6,544
202,483
69,551
272,034
1,786,151
2.058.185
%of
mobile
source
8.8%
2.4%
2.7%
5.8%
0.8%
27.9%
0.28%
17.12%
6.24%
2.41%
74.4%
25.6%
100.0%
-
-
% of total
1.2%
0.3%
0.4%
0.8%
0.11%
3.68%
0.04%
2.26%
0.82%
0.32%
9.8%
3.4%
13.2%
86.8%
100.0%
2020
short tons
25,947
6,957
6,367
11,773
2,421
46,075
760
52,517
16,034
7,044
175,896
63,154
239,050
1,817,722
2.056.773
%of
mobile
source
10.9%
2.9%
2.7%
4.9%
1.0%
19.3%
0.32%
21.97%
6.71%
2.95%
73.6%
26.4%
100.0%
-
-
% of total
1.3%
0.3%
0.3%
0.6%
0.12%
2.24%
0.04%
2.55%
0.78%
0.34%
8.6%
3.1%
11.6%
88.4%
100.0%
-------
Table 3.3-4: 50-State Annual PM,n Baseline Emission Levels
10
for Mobile and Other Source Categories
Category
Small Handheld Nonroad SI
Small Nonhandheld Nonroad SI
Marine SI
SI Recreational Vehicles
Large Nonroad SI (>25hp)
Land-Based Nonroad Diesel
Marine Diesel
Commercial Marine
Locomotive
Aircraft
Total Off Highway
Total Highway
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources
2001
short tons
22,378
5,303
18,301
13,370
1,630
169,258
1,099
41,409
25,173
6,490
304,412
216,032
520,444
2,418,848
2.939.292
%of
mobile
source
4.3%
1.0%
3.5%
2.6%
0.3%
32.5%
0.21%
7.96%
4.84%
1.25%
58.5%
41.5%
100.0%
-
-
% of total
0.8%
0.2%
0.6%
0.5%
0.06%
5.76%
0.04%
1.41%
0.86%
0.22%
10.4%
7.3%
17.7%
82.3%
100.0%
2015
short tons
26,104
6,960
7,991
17,244
2,228
78,132
798
48,448
17,521
7,539
212,964
131,415
344,379
2,236,080
2.580.459
% of mobile
source
7.6%
2.0%
2.3%
5.0%
0.6%
22.7%
0.23%
14.07%
5.09%
2.19%
61.8%
38.2%
100.0%
-
-
% of total
1.0%
0.3%
0.3%
0.7%
0.09%
3.03%
0.03%
1.88%
0.68%
0.29%
8.3%
5.1%
13.3%
86.7%
100.0%
2020
short tons
28,204
7,562
6,920
12,796
2,441
47,500
784
54,649
16,535
8,108
185,500
128,605
314,105
2,269,828
2.583.932
% of mobile
source
9.0%
2.4%
2.2%
4.1%
0.8%
15.1%
0.25%
17.40%
5.26%
2.58%
59.1%
40.9%
100.0%
-
-
% of total
1.1%
0.3%
0.3%
0.5%
0.09%
1.84%
0.03%
2.11%
0.64%
0.31%
7.2%
5.0%
12.2%
87.8%
100.0%
-------
Table 3.3-5: 50-State Annual CO Baseline Emission Levels
for Mobile and Other Source Categories
Category
Small Handheld Nonroad SI
Small Nonhandheld Nonroad SI
Marine SI
SI Recreational Vehicles
Large Nonroad SI (>25hp)
Land-Based Nonroad Diesel
Marine Diesel
Commercial Marine
Locomotive
Aircraft
Total Off Highway
Total Highway
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources
2001
short tons
1,101,646
16,980,598
2,785,192
1,220,580
1,787,054
893,320
6,293
123,806
99,292
263,232
25,261,013
62,083,222
87,344,234
9,014,249
96.358.483
%of
mobile
source
1.3%
19.4%
3.2%
1.4%
2.0%
1.0%
0.01%
0.14%
0.11%
0.30%
28.9%
71.1%
100.0%
-
-
% of total
1.1%
17.6%
2.9%
1.3%
1.85%
0.93%
0.01%
0.13%
0.10%
0.27%
26.2%
64.4%
90.6%
9.4%
100.0%
2015
short tons
948,479
12,274,519
2,189,207
1,982,847
455,196
483,358
8,705
147,449
112,747
305,998
18,908,505
32,912,028
51,820,533
8,734,963
60.555.496
% of mobile
source
1.8%
23.7%
4.2%
3.8%
0.9%
0.9%
0.02%
0.28%
0.22%
0.59%
36.5%
63.5%
100.0%
-
-
%of
total
1.6%
20.3%
3.6%
3.3%
0.75%
0.80%
0.01%
0.24%
0.19%
0.51%
31.2%
54.4%
85.6%
14.4%
100.0%
2020
short tons
1,024,684
13,227,534
2,121,300
1,903,316
302,751
310,258
9,565
158,517
117,785
327,720
19,503,428
32,752,093
52,255,521
8,641,678
60.897.199
% of mobile
source
2.0%
25.3%
4.1%
3.6%
0.6%
0.6%
0.02%
0.30%
0.23%
0.63%
37.3%
62.7%
100.0%
-
-
% of total
1.7%
21.7%
3.5%
3.1%
0.50%
0.51%
0.02%
0.26%
0.19%
0.54%
32.0%
53.8%
85.8%
14.2%
100.0%
-------
Emission Inventory
3.4 Controlled Nonroad Small Spark-Ignition and Marine Engine Emission
Inventory Development
This section describes how the controlled emission inventories were developed for the
small nonroad and Marine SI engines that are subject to the proposal. The resulting controlled
emission inventories are also presented. Section 3.4.1 provides this information for exhaust and
evaporative emissions.
Once again, the inventory estimates presented throughout this section only include
equipment that would be subject to the proposed standards. Specifically for California, this
includes small nonroad SI engines used in farm and construction equipment with maximum
power levels below 175 hp or 130 kW. For Marine SI engines, our analysis assumes that the
proposed standards have no effect because that state already has equivalent exhaust emission
standards and is expected to adopt equivalent evaporative hydrocarbon requirements.
3.4.1 Controlled Exhaust and Evaporative Emissions Estimates for THC, NOx, PM2 5,
PM10, and CO
The controlled exhaust and evaporative emission inventories for small nonroad and
Marine SI engines include the effects of the proposed requirements and all existing applicable
federal emission standards. We generated these inventories by modifying NONROAD2005c to
account for the engine and equipment controls associated with the proposed standards. (See the
baseline emission inventory discussion in Section 3.2 for the changes we made to the publically
available NONROAD2005a model to develop NONROAD2005c.) The modifications that were
made to estimate the controlled emissions inventories are described below.
3.4.1.1 Controlled Exhaust Emission Standards, Zero-Hour Emission Factors and
Deterioration Rates
3.4.1.1.1 Small SI Exhaust Emission Calculations
The proposed Phase 3 emission standards and implementation schedule are shown in
Table 3.4-1. While the standards are proposed to take effect in 2011 for Class II engines and
2012 for Class I engines, we proposing a number of flexibilities for engine and equipment
manufacturers that will allow the continued production and use of engines meeting the Phase 2
standards in limited numbers over the first four years of the Phase 3 program. The
implementation schedule shown in the table is used for modeling purposes only. It is based on
our assumption that engine and equipment manufacturers take full advantage of the flexibilities
being proposed.
3-27
-------
Draft Regulatory Impact Analysis
Table 3.4-1: Phase 3 Emission Standards and Estimated Implementation Schedule
for Class I and II Small SI Engines" (g/kW-hr or Percent)
Engine
Class
Class I
Class II
Requirement
HC+NOx
CO (marine generator
sets only)
Estimated Sales
Percentage
HC+NOx
CO (marine generator
sets only)
Estimated Sales
Percentage
2011
~
~
~
8
5
83
2012
10
5
95
8
5
83
2013
10
5
95
8
5
93
2014
10
5
100
8
5
93
2015+
10
5
100
8
5
100
a Reflects maximum use of proposed compliance flexibilities by engine and equipment manufacturers. Used for
modeling purposes only.
The modeled emission factors corresponding to the proposed Phase 3 standards are
shown in Table 3.4-2. (See Section 3.2.1.2.1 for a discussion of how the model uses zero hour
emission levels (ZML) and deterioration rates (A values.) We developed these new emission
factors based on testing of catalyst-equipped engines both in the laboratory and in-use. A full
description of the emission factor information for Phase 3 engines and the basis for the estimates
can be found in the docket for this rule.
Table 3.2-2: Phase 3 Modeling Emission Factors for Small SI Engines (g/kW-hr)
Class/
Technology
Class f - SV
Class f - OHV
Class ff
HCZML
5.60
5.09
4.25
HC "A"
0.797
0.797
0.797
NOxZML
1.47
1.91
1.35
NOx "A"
0.302
0.302
0.302
CO ZML
319.76
325.06
391.13
CO "A"
0.070
0.070
0.080
PM10
ZML*
0.24
0.05
0.08
PM10
"A"*
1.753
1.753
1.095
* The nonroad model calculates PM2.5 as 92 percent of PM10.
We left the proportion of sales in each technology classification unchanged from those
used for Phase 2 engines. The technology mix was previously shown Table 3.2-2.
Finally, as discussed in more detail in Chapter 6, were developed a new brake-specific
fuel consumption (BSFC) estimate for Class II engines to reflect the expected fuel consumption
benefit associated with the use of additional electronic fuel injection technology on Phase 3
compliant engines. The resulting BFSC for Phase 3 Class II engines is 0.727 pounds per
3-28
-------
Emission Inventory
horsepower-hour (Ib/hp-hr).
3.4.1.1.2 Marine SI Exhaust Emission Calculations
For the control case, we developed new technology classifications for engines meeting
the proposed standards. For outboards and personal watercraft, we no longer will attempt to
determine the technology mix between low emitting technology options (such as DI 2-stroke
versus 4 stroke). The new technology classifications for these engines are simply tied to the
standard. These new technology classifications are titled MO09 and MP09 for outboards and
personal watercraft, respectively. In determining the combined HC+NOx emission factor, we
used the proposed emission standards with a 10 percent compliance margin (with deterioration
factor applied). To determine the NOx emission factors, we used certification data to determine
the sales weighted average NOx for low emission technologies in each power bin. HC was then
determined as the difference between the HC+NOx and the NOx emission factors. Because we
are proposing the same standards for OB and PWC and because they use similar engines, we use
the same HC+NOx emission factors and deterioration factors for both engine types.
Because the proposed CO standard primarily acts as a cap on CO, the CO emission
factors were determined based on the emission factors for existing low emission engines in each
power bin. Fuel consumption factors were calculated in the same manner. Therefore, some
differences are seen between the projected CO and BSFC factors for OB and PWC. No changes
were made to the PM emission factors. Also, the existing deterioration factors for 4-stroke
carbureted engines were applied to the control case (1.05 for HC, NOx, and CO). Table 3.4-3
presents the zero-hour OB/PWC emission factors for the control case.
Table 3.4-3: Control Case Emission Factors for OB/PWC (g/kW-hr)
Power Bin
0-2.2 kW
2.3-4.5 kW
4.6-8.2 kW
8.3-11.9 kW
12.0-18. 6 kW
18. 7-29.8 kW
29.9-37.3 kW
37.4-55. 9 kW
55. 9-74.6 kW
74.7-130.5 kW
130.6+ kW
HC
18.8
17.4
16.7
14.4
15.3
11.9
9.1
8.3
8.3
8.7
10.0
NOx
4.8
3.6
5.6
6.8
4.3
5.7
5.9
5.4
5.4
5.0
3.7
CO
OB PWC
542
357
292
248
205
180
171
173
173
152
139
640
538
243
231
218
206
206
206
206
202
178
BSFC
OB PWC
563
560
555
552
543
528
507
471
471
415
387
563
560
555
552
543
528
507
486
486
394
380
For sterndrive and inboards, we developed a new engine classification similar to the
OB/PWC discussion above. MS4A applies to SD/I engines meeting the proposed standard
through the use of aftertreatment. HC and NOx emission factors are based on test data presented
3-29
-------
Draft Regulatory Impact Analysis
in Chapter 4 for SD/I engines equipped with catalysts. CO emission factors are based on
meeting the proposed standard at the end of useful life (with the deterioration factor applied).
No emission reductions are modeled for PM. The fuel consumption factor for fuel-injected 4-
stroke SD/I engines is applied to the control case. Deterioration factors for catalyst-equipped
engines are the same as those used in the NONROAD2005a model for catalyst-equipped large SI
engines. Table 3.4-4 presents the zero-hour emission factors and the accompanying deterioration
factors for the control case.
Table 3.4-4: Control Case EFs (g/kW-hr) and DFs for SD/I
Engine Category
All (MS4A)
HC
EF
1.80
DF
1.64
NOx
EF
1.60
DF
1.15
CO
EF
55.0
DF
1.36
BSFC
345
3.4.1.2 Controlled Evaporative Emission Rates
Below, we present the effect of the proposed evaporative emission standards on hose
permeation, tank permeation, diurnal, and running loss emission inventories.
3.4.1.2.1 Hose Permeation
Similar to the baseline case, hose permeation rates are based on g/m2/day and are
modeled as a function of temperature. The fuel hose test procedures are based on Fuel CE10 as a
test fuel. Based on data presented in Chapter 5, we would expect in-use emissions on gasoline-
based E10 to be about half of the measured level on Fuel CE10. In addition, we believe that
hose designed to meet the proposed 15 g/m2/day standard on 10 percent ethanol fuel will
permeate at least 50 percent less when gasoline is used. Therefore, we model permeation from
hoses designed to meet 15 g/m2/day on Fuel CE10 to be 7.5 g/m2/day on E10 and 3.75 g/m2/day
on gasoline at 23°C. Consistent with the baseline emission case, we weight the gasoline and E10
emission factors by our estimates of gasoline sales with and without ethanol added.
Fill neck and vent hose containing vapor rather than liquid fuel are not subject to the
proposed standards. Neither is hose on handheld equipment with winter use applications (e.g.
handheld Class V chainsaws). No emission reductions are modeled for these hose types.
3.4.1.2.2 Tank Permeation
Similar to the baseline case, fuel tank permeation rates are based on units of g/m2/day and
are modeled as a function of temperature. We believe that fuel tanks using alternative materials
to meet the proposed 1.5 g/m2/day standard on 10 percent ethanol fuel will typically permeate at
least 50 percent less when gasoline is used. Therefore, we model permeation from fuel tanks to
be 1.5 g/m2/day on fuel E10 and 0.75 g/gal/day at 29°C, regardless of fuel used.
3-30
-------
Emission Inventory
Two exceptions to the above discussion are nylon tanks used on handheld equipment and
metal tanks. For these fuel tanks, we do not include any emissions reductions from baseline.
3.4.1.2.3 Diurnal
We are not proposing a diurnal emission requirement for Small SI equipment. Therefore,
we do not model direct reductions in diurnal emissions. However, we are proposing a limit on
diffusion emissions. As a result, we set the diffusion multiplier to 1.0 for all non-handheld Small
SI equipment for the control case. Note that this multiplier was already set to 1.0 for handheld
equipment in the baseline case. This is equivalent to applying a 32 percent reduction to the
diurnal emission factors.
In the control case for marine, we model portable fuel tanks as having 90 percent lower
diurnal emissions than an open vent system. Also, we set the diffusion multiplier to 1.0 because
the tanks would be sealed. Presumably, the diurnal temperature cycles would build some
pressure in the fuel tank causing hydrocarbons to be released when the tank is opened.
Therefore, we do not model these tanks as having zero diurnal emissions. For PWC, we use the
baseline scenario of sealed systems with a 1.0 psi pressure relief valve. For installed fuel tanks,
we model a 60 percent reduction due to a carbon canister in the fuel line with passive purge.
This reduction is based on data presented in Chapter 5. As in the baseline case, no diffusion is
modeled for PWC and installed fuel tanks.
3.4.1.2.4 Running Loss
For Class I engines, we believe that the proposed running loss control requirement will
be met by routing vapor from the fuel take to the engine air intake system. Therefore, all vapor
generated in the fuel tank should be consumed by the engine, thereby eliminating running loss
emissions. However, there may be some inefficiencies in the system such as vapor escaping out
the intake at idle. Therefore, we model the running loss emission reduction as only 90 percent.
For Class II equipment, we believe that some equipment will inherently meet the proposed
standard because they will have low enough temperature fluctuation in the fuel tanks during
operation to certify by design. Based on the data presented in Chapter 5 on fuel tank
temperatures during operation, we estimate an 80 percent reduction in running loss for Class II
equipment.
3.4.1.3 Controlled Exhaust and Evaporative Inventory Results for THC, NOx,
PM2 5, PM10, CO and SO2
Tables 3.4-5 presents the 50-state controlled emission inventories, respectively, for small
nonroad SI engines. Tables 3.4-6 provides the same information for Marine SI engines.
3-31
-------
Draft Regulatory Impact Analysis
Table 3.4-5: Controlled 50-State Annual Exhaust and Evaporative Emissions for
Small Nonroad Spark-Ignition Engines (short tons)
Year
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
THC
1,099,402
1,074,137
1,039,522
978,760
905,814
849,619
794,827
743,099
705,099
683,397
653,532
605,062
562,800
535,060
519,198
509,608
506,270
507,491
511,030
515,956
522,022
528,733
535,947
543,403
550,981
558,690
566,466
574,280
582,125
590,000
597,896
605,803
613,723
621,652
629,588
637,536
645,494
653,458
661,426
669,399
NOx
101,928
101,261
99,649
97,929
95,779
94,550
92,988
90,638
89,272
88,968
80,103
72,135
65,271
61,428
58,117
56,053
55,149
54,869
54,946
55,241
55,772
56,409
57,121
57,866
58,643
59,447
60,268
61,097
61,934
62,778
63,627
64,479
65,333
66,188
67,045
67,905
68,767
69,631
70,496
71,361
PM2.5
23,163
23,382
23,480
23,483
23,417
23,498
23,804
24,335
24,882
25,402
25,888
26,037
26,172
26,344
26,647
26,985
27,353
27,751
28,159
28,574
28,993
29,416
29,842
30,270
30,699
31,128
31,559
31,989
32,419
32,849
33,280
33,710
34,140
34,571
35,001
35,431
35,862
36,292
36,722
37,153
PM10
25,177
25,416
25,522
25,525
25,453
25,541
25,874
26,451
27,045
27,611
28,139
28,301
28,447
28,635
28,965
29,332
29,732
30,164
30,607
31,058
31,515
31,974
32,437
32,902
33,368
33,835
34,303
34,770
35,238
35,706
36,173
36,641
37,109
37,577
38,044
38,512
38,980
39,448
39,915
40,383
CO
16,108,103
15,560,774
14,941,296
14,382,759
13,784,367
13,369,719
12,919,586
12,285,206
11,775,265
11,492,162
11,091,811
10,733,334
10,467,631
10,363,567
10,317,051
10,334,605
10,408,287
10,515,612
10,642,994
10,782,258
10,932,278
11,087,748
11,247,239
11,408,690
11,572,096
11,738,240
11,905,720
12,073,845
12,242,505
12,411,661
12,581,170
12,750,877
12,920,739
13,090,731
13,260,842
13,431,126
13,601,583
13,772,142
13,942,788
14,113,517
3-32
-------
Emission Inventory
Table 3.4-6: Controlled 50-State Annual Exhaust and Evaporative Emissions for
Marine Spark-Ignition Engines (short tons)
Year
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
THC
935,494
909,607
877,441
841,151
801,985
762,092
724,443
687,350
634,175
582,548
532,769
485,231
441,421
401,152
364,619
330,888
300,138
272,927
249,343
228,847
210,304
194,021
180,805
169,904
160,668
152,898
146,673
141,435
137,294
134,028
131,342
129,305
127,751
126,621
125,891
125,434
125,187
125,113
125,179
125,343
NOx
41,514
43,401
45,661
48,164
50,675
53,207
55,750
58,296
58,835
59,308
59,541
59,635
59,547
59,336
59,024
58,595
58,051
57,378
56,577
55,656
54,638
53,570
52,527
51,497
50,466
49,451
48,468
47,561
47,142
46,859
46,691
46,590
46,531
46,503
46,508
46,536
46,587
46,659
46,755
46,874
PM2.5
15,625
15,092
14,417
13,679
12,886
12,090
11,311
10,553
9,508
8,520
7,584
6,733
5,978
5,286
4,666
4,099
3,588
3,143
2,767
2,448
2,164
,920
,729
,577
,452
,348
,267
,200
,148
,107
,073
,046
,025
,010
999
992
988
986
985
985
PM10
16,984
16,404
15,670
14,869
14,007
13,142
12,295
11,470
10,335
9,261
8,243
7,319
6,497
5,746
5,072
4,455
3,900
3,416
3,007
2,661
2,352
2,087
,880
,714
,578
,465
,377
,304
,248
,203
,166
,137
,114
,097
,086
,079
,074
,071
,070
,071
CO
2,584,786
2,552,368
2,510,927
2,469,934
2,423,497
2,375,768
2,328,182
2,280,928
2,214,580
2,150,304
2,086,638
2,028,270
,976,179
,927,610
,883,241
,842,019
,804,951
,772,827
,743,893
,718,956
,696,117
,676,245
,659,281
,644,771
,632,439
,622,175
,614,086
,608,064
,606,899
,607,678
,610,007
,613,454
,617,823
,622,954
,628,820
,635,236
,642,153
,649,518
,657,283
,665,392
3-33
-------
Draft Regulatory Impact Analysis
3.4.2 Controlled Hazardous Air Pollutant Estimates
The proposed hydrocarbon emission standards for small nonroad and Marine SI engines
will also reduce toxic air pollutants. To calculate the controlled toxic air emission inventories,
we used the same methodology that was used for the baseline inventories along with the results
of the controlled emission inventories for VOC or PM, as appropriate. The methodology is
described in Section 3.2.
Controlled inventories were calculated for the seven major types of air toxic emissions:
benzene, formaldeyde, acetaldehyde, 1,3-butadiene, acrolein, napthalene, and 15 other
compounds grouped together as poly cyclic organic matter (POM) for this analysis.4 Table 3.4-7
presents the 50-state controlled inventories, respectively, small nonroad SI engines. Table 3.4-8
provide the same information for Marine SI engines.
Table 3.4-7: Controlled 50-State Air Toxic Emissions for
Small Nonroad Spark-Ignition Engines (short tons)
Year
2001
2020
2030
Benzene
33,534
16,018
18,341
1,3
Butadiene
5,165
2,214
2,535
Formalde-
hyde
8,035
3,621
4,146
Acetalde-
hyde
2,826
1,697
1,941
Acrolein
462
189
216
Naptha-lene
418
286
329
POM
93
102
118
Table 3.4-8: Controlled 50-State Air Toxic Emissions for
Marine Spark-Ignition Engines (short tons)
Year
2001
2020
2030
Benzene
21,590
4,890
3,117
1,3
Butadiene
1,790
371
230
Formalde-
hyde
1,846
324
200
Acetalde-
hyde
1,354
356
223
Acrolein
179
25
15
Naptha-lene
32
17
12
POM
30
7
4
3.5 Projected Emissions Reductions from the Proposed Rule
This section presents the projected total emission reductions associated with the proposed
rule. We calculated the reductions by subtracting the baseline inventories from Section 3.2 by
the controlled inventories from Section 3.4.
4 The 15 POMs summarized in this chapter are acenaphthene, acenapthylene, anthracene,
benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylkene, beno(k)fluoranthene, chrysene,
dibenzo(a,h)anthracene,fluoranthene, fluorene, ideno(l,2,3,c,c)-pyrene, phenanthrene, andpyrene.
3-34
-------
Emission Inventory
3.5.1 Results for THC, NOx, PM25, PM10, and CO
Tables 3.5-1 presents the 50-state exhaust and evaporative emission inventories and
percent reductions, respectively, for small nonroad SI engines. Tables 3.5-2 provides the same
information for Marine SI engines. Tables 3.5-3 summarizes the combined emission reductions
for the proposal. The earliest proposed Phase 3 standards for small nonroad SI engines begin in
2008. Similar proposed standards affect Marine SI engines one year later. Therefore the
emission reductions are shown beginning in 2008 for small nonroad SI engines and 2009 for
Marine SI engines. Figures 3.5-1 though 3.5-6 show the combined baseline, controlled, and by
contrast the reduction emission inventories over time for small nonroad and Marine SI engines.
3-35
-------
Table 3.5-1: Total 50-State Annual Exhaust and Evaporative Emission Reductions
for Small SI Spark-Ignition Engines (short tons)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
THC
Tons
4,935
10,844
17,085
44,949
95,920
143,686
179,908
205,497
225,684
240,176
250,529
258,899
266,030
272,051
277,458
282,389
287,093
291,705
296,331
300,923
305,489
310,032
314,553
319,057
323,554
328,042
332,523
336,999
341,467
345,926
350,382
354,835
359,285
%
1
2
2
6
14
20
25
28
31
32
33
34
34
34
34
35
35
35
35
35
35
35
35
35
35
35
35
35
35
35
35
35
35
NOx
Tons
0
0
0
9,440
18,305
26,336
31,545
36,315
39,906
42,370
44,232
45,754
47,069
48,150
49,124
50,024
50,893
51,737
52,572
53,398
54,217
55,030
55,837
56,640
57,440
58,238
59,035
59,830
60,623
61,412
62,201
62,988
63,775
%
0
0
0
11
20
29
34
38
42
43
45
45
46
46
47
47
47
47
47
47
47
47
47
47
47
47
47
47
47
47
47
47
47
PM2.5
Tons
0
0
0
0
327
661
947
,100
,216
,301
,356
,399
,435
,466
,495
,520
,543
,566
,590
,614
,638
,662
,686
1,710
1,734
,758
,782
,806
,830
,854
,878
,902
,926
%
0
0
0
0
1
2
3
4
4
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
PM10
Tons
0
0
0
0
356
718
1,029
1,195
1,322
1,414
1,474
1,521
1,560
1,594
1,624
1,652
1,677
1,702
1,728
1,754
1,780
1,807
1,833
1,859
1,885
1,911
1,937
1,963
1,989
2,015
2,042
2,068
2,094
%
0
0
0
0
1
2
3
4
4
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
CO
Tons
0
0
0
334,555
705,503
1,049,398
1,281,497
1,480,027
1,630,861
1,735,277
1,812,911
1,876,142
1,930,518
1,975,208
2,015,250
2,051,946
2,087,252
2,121,545
2,155,582
2,189,270
2,222,715
2,255,912
2,288,860
2,321,627
2,354,303
2,386,904
2,419,451
2,451,948
2,484,331
2,516,608
2,548,836
2,581,029
2,613,191
%
0
0
0
3
6
9
11
13
14
14
15
15
15
15
15
15
15
15
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
-------
Table 3.5-2: Total 50-State Annual Exhaust and Evaporative Emission Reductions
for Marine SI Spark-Ignition Engines (short tons)
Year
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
THC
Tons
17,569
36,295
55,514
76,468
97,088
117,463
137,688
157,614
177,149
196,113
212,803
228,491
243,383
257,338
269,076
279,185
288,385
296,713
303,966
310,552
316,315
321,452
326,194
330,420
334,319
337,908
341,188
344,251
347,161
349,942
352,617
355.217
%
o
J
6
9
14
18
23
27
32
37
42
46
50
54
57
60
62
64
66
67
69
70
71
71
72
72
73
73
73
73
74
74
74
NOx
Tons
1,962
3,920
6,072
8,208
10,336
12,453
14,558
16,650
18,730
20,792
22,892
24,999
27,131
29,226
31,228
33,166
35,051
36,877
38,628
40,267
41,395
42,366
43,206
43,964
44,666
45,325
45,940
46,524
47,077
47,602
48,098
48.567
%
o
J
6
9
12
15
17
20
22
24
27
29
31
33
35
37
39
41
43
44
46
47
47
48
49
49
49
50
50
50
51
51
51
PM2.5
Tons
315
629
941
1,250
1,556
1,858
2,157
2,450
2,737
3,013
3,246
3,461
3,662
3,849
3,997
4,119
4,228
4,327
4,411
4,487
4,553
4,613
4,668
4,719
4,767
4,811
4,852
4,890
4,927
4,962
4,997
5.031
%
3
7
11
16
21
26
32
37
43
49
54
59
63
67
70
72
74
76
78
79
80
81
81
82
82
83
83
83
83
83
84
84
PM10
Tons
343
683
1,023
1,359
1,692
2,019
2,344
2,663
2,975
3,275
3,528
3,762
3,981
4,183
4,344
4,477
4,596
4,703
4,795
4,877
4,949
5,014
5,074
5,130
5,181
5,230
5,274
5,315
5,355
5,394
5,431
5.468
%
o
J
7
11
16
21
26
32
37
43
49
54
59
63
67
70
72
74
76
78
79
80
81
81
82
82
83
83
83
83
83
84
84
CO
Tons
20,607
41,179
62,769
84,241
105,767
127,160
148,443
169,550
190,368
210,784
230,404
249,707
268,906
287,643
305,376
322,243
338,585
354,383
369,306
383,267
393,085
401,570
409,021
415,773
422,048
427,929
433,425
438,637
443,584
448,279
452,729
456.943
%
1
2
3
4
5
6
7
8
10
11
12
13
14
15
16
16
17
18
19
19
20
20
20
20
21
21
21
21
21
21
21
22
-------
Table 3.5-3: Total 50-State Annual Exhaust and
for Small Nonroad and Marine SI Spark-
Evaporative Emission Reductions
Ignition Engines (short tons)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
THC
Tons
4,935
28,413
53,380
100,463
172,387
240,774
297,371
343,185
383,298
417,325
446,643
471,702
494,520
515,434
534,797
551,465
566,279
580,091
593,044
604,889
616,041
626,348
636,005
645,251
653,974
662,361
670,431
678,187
685,717
693,087
700,324
707,452
714,503
%
0
2
4
8
14
19
24
28
31
34
36
38
40
41
43
43
44
45
45
46
46
47
47
47
47
47
47
47
47
47
47
47
47
NOx
Tons
0
1,962
3,920
15,512
26,513
36,672
43,998
50,874
56,556
61,099
65,024
68,646
72,069
75,281
78,350
81,252
84,059
86,788
89,448
92,025
94,484
96,425
98,203
99,845
101,403
102,904
104,360
105,770
107,146
108,489
109,803
111,087
112,342
%
0
1
o
J
10
17
23
27
30
33
35
37
38
39
41
42
43
43
44
45
46
47
47
47
48
48
48
48
48
48
48
49
49
49
PM2.5
Tons
0
315
629
941
1,578
2,217
2,805
3,256
3,666
4,038
4,369
4,645
4,896
5,129
5,343
5,516
5,662
5,794
5,917
6,025
6,125
6,215
6,299
6,379
6,454
6,525
6,593
6,658
6,720
6,781
6,841
6,899
6,957
%
0
1
2
3
5
6
8
9
11
12
12
13
14
14
15
15
15
15
15
16
16
16
16
16
16
16
16
16
16
16
16
15
15
PM10
Tons
0
343
683
1,023
1,715
2,410
3,049
3,539
3,985
4,389
4,749
5,049
5,322
5,575
5,808
5,996
6,154
6,298
6,431
6,549
6,658
6,755
6,847
6,933
7,015
7,092
7,167
7,237
7,305
7,371
7,436
7,499
7,562
%
0
1
2
o
J
5
6
8
9
11
12
12
13
14
14
15
15
15
15
15
16
16
16
16
16
16
16
16
16
16
16
16
15
15
CO
Tons
0
20,607
41,179
397,324
789,744
1,155,165
1,408,656
1,628,471
1,800,412
1,925,645
2,023,696
2,106,545
2,180,225
2,244,115
2,302,893
2,357,322
2,409,495
2,460,130
2,509,965
2,558,576
2,605,982
2,648,997
2,690,429
2,730,649
2,770,076
2,808,952
2,847,380
2,885,372
2,922,968
2,960,192
2,997,115
3,033,757
3,070,134
%
0
0
0
3
6
8
10
12
13
14
14
15
15
15
15
15
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
Note: annualized tons (2008-2038) for HC and NOx are 374,500 and 55,800 at a 7% discount and 431,800 and 64,800 at a 3% discount.
-------
Emission Inventory
Figure 3.5-1: 50-State Annual THC Exhaust and Evaporative Emissions for
Small SI and Marine SI
Figure 3.5-2: 50-State Annual NOx Exhaust Emissions for Small SI and Marine SI
2000 2005 2010 2015 2020 2025 2030 2035 2040
3-39
-------
Draft Regulatory Impact Analysis
Figure 3.5-3: 50-State Annual PM2.5 Exhaust Emissions for Small SI
and Marine SI
Figure 3.5-4: 50-State Annual PM10 Emissions for Small SI and Marine
SI Engines
5
3-40
-------
Emission Inventory
Figure 3.4-5: 50-State Annual CO Emissions from Small SI and
Marine SI Engines
I/)
1
18 000 000
16 000 000
14 000 000
12 000 000
10 000 000
8 000 000
6 000 000
o
. ^^~
>v ^^^*~~^~*~^
^s^ ^^~~~~~^
" —-
Controlled
2000 2005 201 0 201 5 2020 2025 2030 2035 20
Year
3.5.2 Results for Hazardous Air Pollutants
Tables 3.5-4 presents the 50-state exhaust and evaporative air toxics emission inventory
and percent reductions, respectively, for small nonroad SI engines that are expected to
accompany the proposed standards. Table 3.5-5 provides the same information for Marine SI
engines. Tables 3.5-6 summarizes the combined hazardous air pollutant reductions for the
proposal. These results are displayed for 2020 and 2030, when most or all of the engines subject
to the proposed standards are represented in the respective fleets.
3-41
-------
Table 3.5-4: 50-State Air Toxic Emission Reductions for
Small Nonroad Spark-Ignition Engines (short tons)
Year
2020
2030
Benzene
Tons
6,906
8,160
%
30
31
1,3 Butadiene
Tons
955
1,128
%
30
31
Formaldehyde
Tons
1,561
1,845
%
30
31
Acetaldehyde
Tons
732
864
%
30
31
Acrolein
Tons
81
96
%
30
31
Napthalene
Tons
123
146
%
30
31
POM
Tons
5
6
%
4
5
Table 3.5-5: 50-State Air Toxic Emission Reductions for
Marine Snark-Tgnition Engines (short tnns>
Year
2020
2030
Benzene
Tons
4,254
5,955
%
47
66
1,3 Butadiene
Tons
323
440
%
47
66
Formaldehyde
Tons
282
382
%
47
66
Acetaldehyde
Tons
310
426
%
47
66
Acrolein
Tons
22
30
%
47
66
Napthalene
Tons
15
23
%
47
66
POM
Tons
8
11
%
54
75
Table 3.5-6: 50-State Air Toxic Emission Reductions for
Small Nonroad and Marine Snark-Tgnition Engines (short tnns>
Year
2020
2030
Benzene
Tons
11,160
14,116
%
35
40
1,3 Butadiene
Tons
1,278
1,567
%
33
36
Formaldehyde
Tons
1,843
2,227
%
32
34
Acetaldehyde
Tons
1,041
1,290
%
34
37
Acrolein
Tons
103
126
%
33
35
Napthalene
Tons
138
169
%
31
33
POM
Tons
13
17
%
10
12
-------
Emission Inventory
3.6 Emission Inventories Used for Air Quality Modeling
This section describes the methodology we used to develop the emission inventories for
the air quality modeling. The inventories represent emissions for the summer ozone season (i.e.,
June, July, and August) in calendar years 2001, 2015, 2020, and 2030. Emissions were
estimated are for 37 of the most eastern states, which is the geographic area of the air quality
modeling domain.
The emission inputs for the air quality modeling are required early in the analytical
process to ensure there is adequate time to complete the analysis and incorporate the results into
the rulemaking process. Given that lead time requirement, air quality modeling is often based
analytical methods that may be superceded or on a control scenario that does not specifically
match the final set of emission standards. Indeed, for this proposed rulemaking both instances
have occurred. Therefore, this section also describes the changes to our emission inventory
models, modeling inputs, and resulting emission inventories between the preliminary baseline
and control scenarios used for the air quality modeling, and the updated final baseline and
control scenarios for the proposed rule.
3.6.1 Methodology for Air Quality Modeling
The air quality modeling for the proposal is in large part taken from the work performed
for EPA's Clean Air Interstate Rule (CAIR) for stationary sources.22 This approach was adopted
to be consistent with, what was then, EPA's most recent ozone-related rulemaking and to
conserve resources by taking advantage of the existing inventory preparation (i.e., input files)
and results. The CAIR modeling domain consists of 37 states in the eastern U.S. and the District
of Columbia. Emission inventories were developed for the following pollutants: VOC, NOx,
PM2.5, PM10, CO, SOx, and NH3. Air quality results were generated for the summer ozone
season (i.e., June, July, and August) and the CAIR calendar years 2001, 2015, and 2020. We
also modeled calendar year 2030 specifically for this proposal as described below.
The special 2030 calendar year model simulation was performed by preparing CAIR-like
emission inventories for all source categories. For non-mobile sources, we simply carried
forward the inventories from 2020. For mobile sources, we prepared highway and off- highway
inventories for 2030 using the same methodology that was used to prepare the CAIR inventories
for the previous calendar years.
The emissions inventory methodology and results for the nonroad sources and the results
for small nonroad and Marine SI engines are in the docket for this proposed rule.23'24'25'26
3.6.2 Baseline Scenario Emission Inventories
Our preliminary baseline emission inventories without the proposed controls for small
nonroad and Marine SI engines were the same as the CAIR rule's "control" scenario. A special
version of the draft NONROAD2004 model was used to generate the nonroad engine inventories
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Draft Regulatory Impact Analysis
for that rule. That version of the model is referred to as NONROAD2004n. It is identical to the
draft NONROAD2004 model, which was the most recent publically available nonroad model at
the time, except for a modification to allow a separate diesel fuel sulfur value for marine
equipment (an unremarkable feature relative to the proposed rule). NONROAD2004n was
executed within the framework of EPA's National Mobile Source Inventory Model (NMIM) that
links a county-level database to model and collates the output into a single database table. The
resulting estimates for nonroad and Marine SI engines account for local differences in fuel
characteristics and temperatures. NONROAD2004n is discussed in more detail later in this
section.
Table 3.6-1 presents the preliminary 37-state baseline inventories for VOC, NOx, PM2.5,
PM10, and CO during the 3-month summer ozone season that were used in the air quality
modeling for small nonroad and Marine SI engines.5 These values are an aggregation of the
county-level NMEVI results.
Table 3.6-1 37-State Preliminary Baseline Scenario Emissions for
Air Quality Modeling
Application
Small Nonroad SI
Subject to the
Proposal
Marine SI
Year
2001
2020
2030
2001
2020
2030
VOC
264,951
156,401
179,717
264,951
162,488
157,380
PM10
6,738
7,968
9,114
18,397
13,930
14,534
PM25
6,199
7,330
8,385
16,925
12,815
13,371
NOx
37,466
31,477
36,084
18,576
33,061
36,332
CO
4,795,058
6,660,408
7,691,956
927,890
904,964
949,504
The final baseline inventories for the proposal were estimated with a special version of
the NONROAD2005a model, which is the newest public release of our nonroad model. This
special version is named NONROAD2005c. Generally, we revised the model to incorporate new
test results for nonhandheld Small SI engines that comply with the existing Phase 2 standards.
Also, the model was modified to acknowledge the continued use of side-valve engine designs in
Class I nonhandheld engines meeting those standards. In the Phase 2 rulemaking for small
nonroad SI engines, side-valve technology was assumed to be superceded by overhead valve
designs and was modeled accordingly. In reality, side-valve technology has continued to be used
in small nonroad SI engines. The revisions we made to develop this new version is also
described in Section 3.2.
Table 3.6-2 compares the preliminary and final 37-state baseline scenario inventories for
5 Inventories for SOx and NH4 are not important for the purposes of this discussion and can be found in the
docket along with information on the other pollutants presented here. See reference 26.
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Emission Inventory
small nonroad and Marine SI engines. This information is presented primarily for information
purposes, since it is the percentage difference between a model's baseline and control scenario
that is used for comparing the inventories from the final proposal to those used in the air quality
modeling as discussed further in Section 3.6.3. As shown, the difference in the baseline
scenarios between the two models ranges from about -2 percent for VOC in 2020 to about 50
percent for PM2.5 in 2020 for the combined Small SI engine and Marine SI engine categories.
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Table 3.6-2: Comparison of 37-State Baseline Scenario Emissions for
Preliminary Air Quality Modeling and Final Proposal
Applications
Small Nonroad
SI Subject to
the Proposal
Marine SI
Total
Year
2020
2030
2020
2030
2020
2030
VOC [short tons]
Final
219,404
253,162
230,222
228,081
449,626
481,243
Preliminary
156,401
179,717
162,488
157,380
318,889
337,096
Difference
63,003
73,445
67,734
70,701
(4,731)
2,744
NOX [short tons]
Final
26,947
31,101
40,949
44,949
67,896
76,050
Preliminary
31,477
36,084
33,061
36,332
64,538
72,415
Difference
(4,530)
(4,983)
7,888
8,617
(12,418)
(13,600)
PM25 [short tons]
Final
7,946
9,141
3,108
3,008
11,054
12,149
Preliminary
7,330
8,385
12,815
13,371
20,146
21,756
Difference
616
756
(9,707)
(10,363)
10,323
11,119
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Emission Inventory
Table 3.6-2 (Cont'd)
Comparison of 37-State Baseline Scenario Emissions for
Preliminary Air Quality Modeling and Final Proposal
Applications
Small Nonroad
SI Subject to the
Proposal
Marine SI
Total
Year
2020
2030
2020
2030
2020
2030
PM10 [short tons]
Final
8,637
9,936
3,378
3,270
12,015
13,206
Preliminary
7,968
9,114
13,930
14,534
21,898
23,648
Difference
669
822
(10,552)
(11,264)
(9,883)
(10,442)
CO [short tons]
Final
3,832,891
4,414,165
1,040,807
1,061,971
4,873,698
5,476,136
Preliminary
6,660,408
7,691,956
904,964
949,504
7,565,372
8,641,460
Difference
(2,827,517)
(3,277,791)
135,843
112,467
(2,691,674)
(3,165,324)
These baseline inventory differences are obviously due to the differences in
NONROAD2004n and the special version of the model that we developed for the final proposal,
i.e., NONROAD2005c, as well as the inputs to the models. As already mentioned,
NONROAD2004n is equivalent to publically available draft NONROAD model with a revision
that is insignificant for the purposes of the proposal as described above. The most substantial
changes between the two models occurred between publically available NONROAD2004 and
the publically available NONROAD2005a. The principle revisions that are relevant to this
proposal generally include:
1) All new evaporative emission categories for fuel tank permeation, hose
permeation, hot soak, and running losses;
2) Added capability to model emissions using daily values for temperature and
gasoline volatility at the national and state level;
3) Revised methodology for calculating diurnal evaporative emissions;
4) Added the effect of evaporative emission standards for recreational vehicles and
large spark-ignition engines; and
5) Updated geographic allocation factors to distribute national equipment
populations to state and local jurisdictions; and
The additional changes we made from NONROAD2005a to develop NONR2005c for the
proposal are important, but less significant. These revisions are described in detail in
Section 3.2.
3.6.3 Control Scenario Emission Inventories
At the time we were ready to develop the control scenario for the air quality analysis, our
modeling techniques and emission inputs significantly improved beyond NONROAD2004a
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Draft Regulatory Impact Analysis
model, which was used to generate the CAIR-related base case. So we created a special version
of NONROAD2004a to better estimate the exhaust and evaporative refueling emissions for small
nonroad and Marine SI engines. The special version of the model was designated as
NONROAD2004n2. We also created special spreadsheet models to expand and improve our
estimates of the other evaporative emissions from these engines, i.e., diurnal (including
effusion), running loss, hot soak, and hose and tank permeation.
The principle changes that were incorporated into NONROAD2004n2 for exhaust and
refueling emissions are:
1. Updated the estimated sales fractions by engine class and technology to account
for the continued sales of Class I Small SI engines using side-valve technology
(we assumed these engines would be replaced with overhead-valve technology in
the Phase 2 standard rulemaking);
2. Revised emission factors and deterioration rates for Class I Small SI engines
subject to Phase 2 standards based on preliminary testing;
3. Updated Marine SI engine population distributions by horsepower category; and
4. Updated Marine SI engine emission factors for hydrocarbons, CO, and NOx.
The principle changes that were incorporated into the spreadsheet models for the other
evaporative emissions are:
1. Added all new evaporative emission categories for fuel tank and hose permeation;
and
2. Updated the methodology for diurnal evaporative emissions.
These new tools were utilized to derive the preliminary control inventories for the air
quality modeling. More specifically, we constructed alternative baseline and control scenarios
for small nonroad and Marine SI engines with the NONROAD2004n2 model for exhaust and
evaporative refueling emissions, and the new spreadsheet models for the other evaporative
emissions. The percent change in emissions from the alternative baseline to the alternative
control inventory for each pollutant was then applied to the respective CAIR-related preliminary
baseline inventories to generate the preliminary control scenario inventories for the proposed
rule. This approach was taken to preserve the existing air quality modeling input files, while still
reflecting the full scope of the emission reductions from the proposed rule. This methodology
has been documented in detail and a copy of the NONROAD2004n2 model and evaporative
emission spreadsheets have been placed in the docket for this proposal.
For this proposal, the specific emission standards and associated control requirements
were not fully identified when the air quality modeling was performed. As a result, we modeled
a variety of preliminary control scenarios with the improved inventory tools described above to
accommodate a range of possible regulatory outcomes. The air quality modeling outcomes for
the preliminary scenario that most closely matches the percent change in emissions associated
with the final control scenario will be used in Chapter 8 to estimate the health and welfare
benefits of the proposal. Using the percentage reduction in emissions to select the appropriate
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Emission Inventory
preliminary control scenario matches the methodology that was originally used to develop the
preliminary air quality control scenario itself, as described in the preceding paragraph.
Before selecting the preliminary air quality control scenario for our benefits assessment
in Chapter 8, we would like to reiterate that the final control scenario inventories for the proposal
were estimated with a special version of the NONROAD2005a model, just as we used for the
final baseline scenario inventories. It should be noted that NONROAD2005a incorporates and
expands upon the modeling improvements described above for NONROADn2 and the
evaporative spreadsheet models, which were used to generate the percentage reduction factors
associated with the alternative baseline and control scenarios. Of course, the special version
reflects further modeling improvements for the proposal. Section 3.6.2 generally describes the
changes we made to the NONROAD2005a base model. A more detailed discussion of the
special version of the model is also contained in Section 3.2.
Table 3.6-3 compares the percentage emission reductions that are associated with the
final control scenario and preliminary air quality control scenario that most closely matches the
final scenario for the 37-state modeling domain. The inventories are not shown for 2001 or 2015
because the proposed requirements either have no effect on the inventories, i.e., 2001, or have
not yet significantly "rolled over" into the fleet of equipment, i.e., 2015. Also, results are
presented only for the two most important pollutants relative to this rule for selection purposes,
i.e., VOC and NOx. As shown, the emission reductions are, on average, very close to the final
control scenario based on the selection criteria. Therefore, this case is selected as the most
representative preliminary control scenario relative to the air quality results associated with the
proposal.
Table 3.6-4 directly compares the emission inventories (i.e., tons) for the selected
preliminary control scenario to the final control scenario. As previously described, this
information is presented primarily for information purposes, since it is the percentage difference
between a model's baseline and control scenario that is used for comparing the inventories from
the final proposal to those used in the air quality modeling. As shown, the difference in the
control scenarios for the two models ranges from about -27 percent for CO in 2030 to about 50
percent for VOC in 2030 for the combined Small SI engine and Marine SI engine categories.
As with the baseline scenarios, the differences in the preliminary and final control
scenarios inventories are due to the differences in models and inputs used in the analysis. Unlike
the baseline scenario discussion, however, the comparison of these differences is substantially
complicated by the use of not just two, but three different modeling platforms, i.e.,
NONROAD2004n (used for the CAIR-related base case), NONROADn2 and the spreadsheet
models (used for the percent reduction factors), and the special version of NONROAD2005a
(used for the final control scenario). Generally, the greatest differences result from using the
NONROAD2004n model for the preliminary baseline scenario (from which the preliminary
control scenario inventories were directly calculated) and the special version of
NONROAD2005a model. The differences between these two models is described in
Section 3.6.2. We expect that any new air quality modeling that may be needed for the final rule
would be based on a single, consistent modeling platform.
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Table 3.6-3: Comparison of 37-State Emission Reductions for Small Nonroad and Marine SI Engines
for Emission Benefit Analysis Purposes (Tons or Percent Reduction/Year)
Pollutant
VOC
NOx
Year
2020
2030
2020
2030
Preliminary Proposal
(Air Quality Modeling)
Base
(tons)
318,889
337,096
64,538
72,415
Control
(tons)
168,589
147,664
41,331
40,341
Reduction
(tons)
150,300
189,432
23,207
32,074
Percent
Reduction
(%)
47
56
36
44
Final Proposal
Base
(tons)
446,626
481,243
67,586
76,049
Control
(tons)
252,287
223,834
42,802
40,503
Reduction
(tons)
197,339
257,409
24,754
35,546
Percent
Reductio
(%)
44
54
37
47
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Table 3.6-4: Comparison of 37-State Control Scenario Emissions for
Preliminary Air Quality Modeling Scenario and Final Proposal (Tons/Year)
Applications
Small Nonroad
SI Subject to
the Proposal
Marine SI
Total
Year
2020
2030
2020
2030
2020
2030
VOC [short tons]
Final
138,406
157,626
113,881
66,208
252,287
223,834
Preliminary
92,605
105,348
75,984
42,316
168,589
147,664
Difference
45,801
52,278
37,897
23,892
83,698
76,170
NOX [short tons
Final
14,416
16,306
28,386
24,197
42,802
40,503
Preliminary
15,240
17,107
26,091
17,107
41,331
34,214
Difference
(824)
(801)
2,295
7,090
1,471
6,289
PM2S [short tons]
Final
7,507
8,627
1,287
582
8,794
9,209
Preliminary
7,330
8,384
3,412
756
10,742
9,140
Difference
177
243
(2,125)
(174)
(1,948)
69
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Draft Regulatory Impact Analysis
Table 3.6-4 (Cont'd)
Comparison of 37-State Control Scenario Emissions for
Preliminary (Nominal) Air Quality Modeling and Final Proposal
Applications
Small Nonroad
SI Subject to the
Proposal
Marine SI
Total
Year
2020
2030
2020
2030
2020
2030
PM10 [short tons]
Final
8,160
9,377
1,399
633
9,559
10,010
Preliminary
7,967
9,113
3,709
821
11,676
9,934
Difference
193
264
(2,310)
(188)
(2,117)
76
CO [short tons]
Final
3,231,266
3,703,736
908,162
848,425
4,139,428
4,552,161
Preliminary
4,868,575
5,593,529
726,853
675,398
5,595,428
6,268,927
Difference
(1,637,309)
(2,316,989)
181,309
173,027
(1,456,000)
(1,716,766)
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Emission Inventory
Chapter 3 References
1. "NONROAD2005a Emissions Inventory Model and Documentation," Memorandum and attachment from
Richard S. Wilcox to Docket EPA-HQ-OAR-2004-0008, U.S. Environmental Protection Agency, Office of
Transportation and Air Quality, Ann Arbor, Michigan, February 5, 2007. Docket Identification EPA-HQ-OAR-
2004-0008-0517.
2. "NONROAD2005c Emissions Inventory Model," Memorandum and attachment from Richard S. Wilcox to
Docket EPA-HQ-OAR-2004-0008, U.S. Environmental Protection Agency, Office of Transportation and Air
Quality, Ann Arbor, Michigan, February 5, 2007. Docket Identification EPA-HQ-OAR-2004-0008-0517.1.
3. "Updates to Phase 2 Technology Mix, Emission Factors, and Deterioration Rates for Spark-Ignition Nonroad
Nonhandheld Engines at or below 19 Kilowatts for the NONROAD Emissions Inventory Model," Memorandum
from Phil Carlson to Docket EPA-HQ-OAR-2004-0008, U.S. Environmental Protection Agency, Office of
Transportation and Air Quality, Ann Arbor, Michigan, March 6, 2000. Docket Identification EPA-HQ-OAR-2004-
0008-0543.
4. "Phase 3 Technology Mix, Emission Factors, and Deterioration Rates for Spark-Ignition Nonroad Nonhandheld
Engines at or below 19 Kilowatts for the NONROAD Emissions Inventory Model," Memorandum from Phil Carlson
to Docket EPA-HQ-OAR-2004-0008, March 8, 2007, U.S. Environmental Protection Agency, Office of
Transportation and Air Quality, Ann Arbor, Michigan, December 2005. Docket Identification EPA-HQ-OAR-2004-
0008-0546.
5. "NONROAD2005a Emissions Inventory Model and Documentation," Memorandum and attachment from
Richard S. Wilcox to Docket EPA-HQ-OAR-2004-0008, U.S. Environmental Protection Agency, Office of
Transportation and Air Quality, Ann Arbor, Michigan, February 5, 2007. Docket Identification EPA-HQ-OAR-
2004-0008-0517.
6. "Exhaust Emission Factors for Nonroad Engine Modeling; Spark-Ignition, Report No. OlOe," U.S. Environmental
Protection Agency, Office of Transportation and Air Quality, Ann Arbor, Michigan, EPA420-R-05-019, December
2005. Docket Identification EPA-HQ-OAR-2004-0008-0398.
7. "Updates to Technology Mix, Emissions Factors, Deterioration Rates, Power Distribution, and Fuel Consumption
Estimates for SI Marine Engines in the NONROAD Emissions Inventory Model," Memorandum from Michael
Samulski to Docket EPA-HQ-OAR-2004-0008, U.S. Environmental Protection Agency, Office of Transportation
and Air Quality, Ann Arbor, November 30, 2005. Docket Identification EPA-HQ-OAR-2004-0008-0361.
8. "Nonroad Evaporative Emission Rates, Report No. 012c," U.S. Environmental Protection Agency, Office of
Transportation and Air Quality, Ann Arbor, Michigan, December 2005. Docket Identification EPA-HQ-OAR-2004-
0008-0362.
9. "Domenici-Barton Energy Policy Act of 2005," 109th Congress, U.S. House of Representatives and U.S. Senate,
July 26, 2005. Docket Identification EPA-HQ-OAR-2004-0008-0268.
10. "Annual U.S. Petroleum Supply and Demand: Base Case," Energy Information Administration\Short-Term
Energy Outlook ~ September 2006, Table A5, http://www.eia.doe.gov/emeu/steo/pub/a5tab.html, Docket
IdentificationEPA-HQ-OAR-2004-0008-0472
11. "Annual Energy Outlook 2006; With Projections to 2030," Energy Information Administration,
DOE/EIA-0383(2006), December 2005, http://www.eia.doe.gov/oiaf/aeo/excel/figure91_data.xls (gasoline), Docket
Identification EPA-HQ-OAR-2004-0008-0471.
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Draft Regulatory Impact Analysis
12. "Annual Energy Outlook 2006; With Projections to 2030," Energy Information Administration,
DOE/EIA-0383(2006), December 2005, http://www.eia.doe.gov/oiaf/aeo/excel/figure95_data.xls (ethanol), Docket
IdentificationEPA-HQ-OAR-2004-0008-0470.
13. "Fuel and Oil Hoses," Recommended Practice J30, Society of Automotive Engineers, June 1998. Docket
Identification EPA-HQ-OAR-2004-0008-0176.
14. "Personal Watercraft Fuel Systems," Recommended Practice J2046, Society of Automotive Engineers, January,
19, 2001. Docket Identification EPA-HQ-OAR-2004-0008-0179.
15. "Marine Fuel Hoses," Recommended Practice J1527, Society of Automotive Engineers, Revised February 1993.
Docket Identification EPA-HQ-OAR-2004-0008-0177.
16. "Handheld Fuel Lines," email from William Guerry, representing Outdoor Power Equipment Institute, to Glenn
Passavant and Mike Samulski, U.S. Environmental Protection Agency, Office of Transportation and Air Quality,
Ann Arbor, Michigan, July 6, 2005. Docket Identification EPA-HQ-OAR-2004-0008-0126.
17. Letter from Jim Hardin, Grady-White Boats, to Phil Carlson, U.S. Environmental Protection Agency, Office of
Transportation and Air Quality, Ann Arbor, Michigan, July 25, 2006. Docket Identification EPA-HQ-OAR-2004-
0008-0437.
18. "Permeation of Gasoline and Gasoline-Alcohol Fuel Blends Through High-Density Polyethylene Fuel Tanks
with Different Barrier Technologies," D. Kathios and R. Ziff, SAE Paper 920164, 1992, Docket Identification
EPA-HQ-OAR-2004-0008-0172.
19. U. S. Environmental Protection Agency. 2006. National-Scale Air Toxics Assessment for 1999.
Http://www.epa.gov/ttn/ate/natal999.
20. "Hazardous Air Pollutant Emission Inventories for the Small Nonroad and Marine Engine Proposed
Rulemaking," Memorandum and attachments from Richard Wilcox, U.S. Environmental Protection Agency, Office
of Transportation and Air Quality, Ann Arbor, Michigan, February 7, 2007. Docket Identification EPA-HQ-OAR-
2004-0008-0516.
21. "Comparison of Small Nonroad and Marine Spark-Ignition Emissions to Stationary and Other Mobile Source
Emission Inventories," Memorandum and attachment from Richard Wilcox, U.S. Environmental Protection Agency,
Office of Transportation and Air Quality, Ann Arbor, Michigan, March 12, 2007. Docket Identification EPA-HQ-
OAR-2004-0008-0540.
22. "Technical Support Document for the Proposed Small Spark Ignition (SI) and Marine SI Emissions Standards:
Ozone Air Quality Modeling," U.S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina, EPA-454/R-07-006,
November 2006. Docket Identification EPA-HQ-OAR-2004-0008.
23. "Air Quality Modeling Exhaust Emission Inputs for the Spark-Ignition Small Nonroad and Marine Engine
Proposed Rulemaking," Memorandum from Phil Carlson to Docket EPA-HQ-OAR-2004-0008, U.S. Environmental
Protection Agency, Office of Transportation and Air Quality, Ann Arbor, Michigan, March 13, 2007. Docket
IdentificationEPA-HQ-OAR-2004-0008-0559.
24. "Air Quality Modeling Evaporative Emission Inputs for the Spark-Ignition Small Engine and Marine Engine
Proposed Rulemaking" Memorandum from Michael Samulski to Docket EPA-HQ-OAR-2004-0008, U.S.
Environmental Protection Agency, Office of Transportation and Air Quality, Ann Arbor, Michigan, March 8, 2007.
Docket Identification EPA-HQ-OAR-2004-0008-0529.
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Emission Inventory
25. "Development of Air Quality Modeling Emission Inventories for the Small Nonroad and Marine Spark-Ignition
Engine Proposed Rulemaking," Memorandum from Harvey Michaels to Docket EPA-HQ-OAR-2004-0008, U.S.
Environmental Protection Agency, Office of Transportation and Air Quality, Ann Arbor, Michigan, December 11,
2006. Docket Identification EPA-HQ-OAR-2004-0008-0518.
26. "Electronic Media Supporting Development of Air Quality Modeling Emissions Inventories for the Small
Nonroad and Marine Spark-Ignition Engine Proposed Rulemaking," Memorandum and attachments from Harvey
Michaels, U.S. Environmental Protection Agency, Office of Transportation and Air Quality, Ann Arbor, Michigan,
December 11, 2006. Docket Identification EPA-HQ-OAR-2004-0008-0515.
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Feasibility of Exhaust Emission Control
CHAPTER 4: Feasibility of Exhaust Emission Control
Section 213(a)(3) of the Clean Air Act presents statutory criteria that EPA must evaluate
in determining standards for nonroad engines and vehicles including marine vessels. The
standards must "achieve the greatest degree of emission reduction achievable through the
application of technology which the Administrator determines will be available for the engines
or vehicles to which such standards apply, giving appropriate consideration to the cost of
applying such technology within the period of time available to manufacturers and to noise,
energy, and safety factors associated with the application of such technology." This chapter
presents the technical analyses and information that form the basis of EPA's belief that the
proposed exhaust emission standards are technically achievable accounting for all the above
factors.
The proposed exhaust emission standards for Small SI engines and Marine SI engines are
summarized in the Executive Summary. This chapter begins with a current state of technology
for spark-ignition (SI) engines and the emission control technologies expected to be available for
manufacturer and continues with a presentation of available emissions data on baseline
emissions and on emission reductions achieved through the application of emission control
technology. In addition, this chapter provides a description new proposed test procedures
including not-to-exceed requirements.
4.1 General Description of Spark-Ignition Engine Technology
The two most common types of engines are gasoline-fueled engines and diesel-fueled
engines. These engines have very different combustion mechanisms. Gasoline-fueled engines
initiate combustion using spark plugs, while diesel fueled engines initiate combustion by
compressing the fuel and air to high pressures. Thus these two types of engines are often more
generally referred to as "spark-ignition" and "compression-ignition" (or SI and CI) engines, and
include similar engines that use other fuels. SI engines include engines fueled with liquid
petroleum gas (LPG) and compressed natural gas (CNG).
4.1.1 Basics of Engine Cycles
Spark ignition engines may be of two-stroke or four-stroke which refers to the number of
piston strokes per combustion cycle. Handheld Small SI equipment typically use two-stroke
engines while larger non-handheld equipment use four-stroke engines. Outboard and personal
watercraft (OB/PWC) engines, until the advent of recent environmental regulations, were
generally two-stroke engines. They are now a mix of two- and four-stroke engines. Sterndrive
and inboard (SD/I) engines are primarily SI four-stroke engines.
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Draft Regulatory Impact Analysis
4.1.1.1 Two-Stroke Engines
"Two-stroke" refers to the number of piston strokes per combustion cycle. These two
strokes, compression and expansion, occur in one revolution of the crankshaft. During the
expansion stroke the piston moves downward. As the piston nears its lowest position, the intake
and exhaust ports are opened. While these ports are open, a fresh charge of fuel and air is
pushed into the cylinder which, in turn, helps force the burned gases from the previous cycle out
of the exhaust port. During the compression stroke, the intake and exhaust ports close and the
fresh charge is compressed. As the piston approaches it's highest position, a spark-plug ignites
the fresh charge to generate combustion. The force from the combustion acts on the piston to
move it downward, thereby causing the expansion stroke and generating power.
In traditional two-stroke engine designs, the engines are crankcase-scavenged and
carbureted with intake and exhaust ports on the cylinder walls. The advantage of this engine
design is simplicity (low number of moving parts) and a high power to weight ratio of the
engine. In this design, the carburetor meters fuel into the intake air which is then routed to the
crankcase. The motion of the drive shaft then pressurizes the charge. Oil is typically blended
into the fuel to provide cylinder and reciprocating assembly lubrication. When the piston lowers,
it exposes the intake port on the side of the cylinder wall which allows the pressurized fuel/air
charge to enter the cylinder. At the same time, the exhaust port is exposed allowing burned
gases to escape the cylinder. Because both ports are open at the same time, some of the fresh
charge can exit the exhaust port. These fuel losses are known as "short-circuiting" or
"scavenging" losses and can result in 25 percent or more of the fuel passing through the cylinder
unburned. As the piston moves up, the intake and exhaust ports are covered and combustion is
initiated.
An emerging technology for reducing emissions and scavenging losses from two-stroke
engines is direct-injection. This is used primarily on larger outboard and personal watercraft
engines (37 kW and up) to meet exhaust emission standards. In a direct-injected engine, charge
air is used to scavenge the exhaust gases. Once the exhaust valve closes, fuel is injected into the
charge air and ignited with a spark-plug. Because the exhaust valve is closed during most or all
of the injection event, short-circuiting losses are minimized. Also, because the fuel is not used to
lubricate the crankcase, oil does not need to be blended into the fuel. As a result, much less oil is
used.
4.1.1.2 Four-Stroke Engines
Four-stroke engines are used in many different applications. Virtually all highway
motorcycles, automobiles, trucks and most buses are powered by four-stroke SI engines. Four-
stroke engines are also common in off-road motorcycles, all-terrain vehicles (ATVs), boats,
airplanes, and numerous nonroad applications such as lawn mowers, lawn and garden tractors,
and generators, pressure washers and water pumps to name just a few.
A "four-stroke" engine gets it's name from the fact that the piston makes four passes or
strokes in the cylinder to complete an entire cycle. The strokes are intake, compression,
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Feasibility of Exhaust Emission Control
expansion or power, and exhaust. Two of the strokes are downward (intake & expansion) and
two of the strokes are upward (compression & exhaust). The four strokes are completed in two
revolutions of the crankshaft. Valves in the combustion chamber open and close to route gases
into and out of the combustion chamber or create compression.
Figure 4.1-1: 4-Stroke Cycle
2, Compression 3. Expansion
4, Exhaust
The first step of the cycle is for an intake valve to open during the intake stroke allowing
a mixture of air and fuel to be drawn into the cylinder while an exhaust valve is closed and the
piston moves down the cylinder. The piston moves from top dead center (TDC) or the highest
piston position to bottom dead center (BDC) or lowest piston position. This displacement of the
piston draws air and fuel past the open intake valve into the cylinder.
During the compression stroke, the intake valve closes and the momentum of the
crankshaft moves the piston up the cylinder from BDC to TDC, compressing the air and fuel
mixture. As the piston nears TDC, at the very end of the compression stroke, the air and fuel
mixture is ignited by a spark plug and the air and fuel mixture begins to burn. As the air and fuel
mixture burns, pressures and temperatures increase and the products of combustion expand in the
cylinder, which causes the piston to move back down the cylinder, transmitting power to the
crankshaft during the expansion or power stroke. Near the bottom of the expansion stroke, an
exhaust valve opens and as the piston moves back up the cylinder, exhaust gases are pushed out
through the exhaust valve to the exhaust manifold to complete the exhaust stroke, finishing a
complete four-stroke cycle.
4.1.2 Exhaust Emissions from Nonroad SI Engines
Hydrocarbon (HC) and CO emissions are products of incomplete combustion. The level
of CO exhaust emissions is primarily a function of the air-to-fuel ratio at which an engine is
operated. Hydrocarbon emissions formation mechanisms are somewhat more complex, and
appear to be primarily related to:
1. Quenching of the air/fuel mixture at the walls of the combustion chamber
2. Filling of crevice volumes with the air/fuel mixture that remains unburned due to flame
quenching at the entrance to the crevice
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Draft Regulatory Impact Analysis
3. Lubricant absorption and desorption of fuel compounds
4. Partial combustion during an operating cycle or even complete misfiring of the air/fuel
mixture during the cycle
5. Entrainment and incomplete combustion of lubricant
As a result, a number of design and operational variables have an impact on HC
emissions, including air-to-fuel ratio; combustion chamber design and geometry; homogeneity of
the air/fuel charge; intake port geometry and the degree of induced air/fuel charge motion;
ignition energy, dwell, and timing; the effectiveness of the cooling system; and oil consumption.
NOx emissions from SI engines are primarily emissions of nitric oxide (NO). Nitrogen
in the intake air reacts with oxygen at high temperatures primarily via the Zeldovich mechanism
to form NO. Thus variables that impact combustion temperatures can have a significant impact
on NO formation and NOx exhaust emissions. These include air-to-fuel ratio, spark timing and
the quantity of residual exhaust gases carried over between engine firing cycles (either
intentional, such as EGR, or unintentional, such as poor cylinder scavenging).
Particulate matter (PM) emissions from SI engines consists primarily of semi-volatile
organic compounds from the engine lubricant together with elemental-carbon soot formed from
pyrolysis of fuel and lubricant during combustion.
4.1.2.1 Air-to-fuel ratio
The calibration of engine air-to-fuel ratio affects torque and power output, fuel
consumption (often indicated as Brake Specific Fuel Consumption or BSFC), engine
temperatures, and emissions for SI engines. The effects of changing the air-to-fuel ratio on
emissions, fuel consumption and torque (indicated as Brake Mean Effective Pressure or BMEP,
which is torque corrected for engine volumetric displacement) are shown in Figure 3-1.l
In the past, manufacturers have calibrated fuel systems of nonroad SI engines for rich
operation. This was done in part to reduce the risk of lean misfire due to imperfect mixing of the
fuel and air and variations in the air-fuel mixture from cylinder to cylinder. Rich operation at
between approximately 12.5:1 and 13:1 air-to-fuel ratio also generally increased engine torque
output (figure 4.1-1) and prevented lean air-to-fuel ratio excursions during application of
transient loads to the engine. Rich operation also has been used to reduce piston, combustion
chamber, cylinder and exhaust port temperatures, thus reducing the thermal load on the cooling
system, a particularly important issue with air-cooled engines. Operation at air-to-fuel ratios
richer than approximately 13:1 or 13.5:1 can limit the effectiveness of, or pose design challenges
for, post-combustion catalytic exhaust emission controls for HC and CO emissions but work well
for catalytic reduction of NOx. At the same time, because a rich mixture lacks sufficient oxygen
for complete combustion, it results in increased fuel consumption rates and higher HC and CO
emissions.
As can be seen from the figure, the best fuel consumption rates occur when the engine is
running lean of the stoichiometric air-to-fuel ratio (approximately 14.6:1 air-to-fuel ratio for
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Feasibility of Exhaust Emission Control
typical gasolines), but lean operational limits are bounded by the onset of abnormal combustion
(e.g., lean misfire and combustion knock), the ability to pick up load, and exhaust port
temperatures (particularly with air-cooled engines). Many air-cooled engines are limited by
heat-rejection to operation that starts approximately at stoichiometry for light loads, and is rich
of stoichiometry as load is increased.
With the use of more advanced fuel systems, manufacturers would be able to improve
control of the air-fuel mixture in the cylinder. This improved control allows for leaner operation
that is closer to a stoichimetric air-to-fuel ratio without increasing the risk of abnormal
combustion. This can be enhanced through careful selection of intake port geometry and
combustion chamber shape to induce turbulence into the air/fuel cylinder charge. The leaner air-
to-fuel ratios (e.g., operating just rich of stoichiometry) resulting from advanced fuel systems
and intake charge turbulence can significantly reduce HC and CO emissions and fuel
consumption, and can provide more oxygen in the exhaust for improved catalytic control of HC
and CO. Leaner air-to-fuel ratios, however, can increase NOx emissions due to higher
combustion temperatures, particularly for engines that are not equipped with exhaust catalysts.
More advanced fuel systems would allow tailoring of the air to fuel ratio to allow good transient
response and to add enrichment at higher load conditions for engine and catalyst protection and
to reduce engine-out NOx emissions. High-load enrichment is particularly important for air-
cooled engines, since high-load operation at leaner air-to-fuel ratios could also increase
hydrocarbon emissions and PM emissions if the higher cylinder temperatures encountered result
in a significant increase in cylinder-bore distortion and lubricating oil consumption.
Figure 4.1-2: Effects of Air-to-Fuel Ratio on Torque Output, Fuel Consumption and
Emissions for Naturally Aspirated Spark Ignition Engines.
4.1.2.2 Spark-timing
For each engine speed and air-fuel mixture, there is an optimum spark-timing that results
in peak torque ("Maximum Brake Torque" or "MET" timing). If the spark is advanced from
MET, more combustion occurs during the compression stroke. If the spark is retarded from
MET, peak cylinder pressure is decreased because too much combustion occurs later in the
expansion stroke generating less useable torque. Timing retard may be used as a strategy for
reducing NOx emissions, because it suppresses peak cylinder temperatures that lead to high NOx
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Draft Regulatory Impact Analysis
levels. Timing retard also results in higher exhaust gas temperatures, because less mechanical
work is extracted from the available energy. This may have the benefit of warming catalyst
material to more quickly reach the temperatures needed to operate effectively during light-load
operation.2 Some automotive engine designs rely on timing retard at start-up to reduce cold-start
emissions.
Advancing the spark-timing at higher speeds gives the fuel more time to burn. Retarding
the spark timing at lower speeds and loads avoids misfire. With a mechanically controlled
engine, a fly-weight or manifold vacuum system adjusts the timing. Mechanical controls,
however, limit the manufacturer to a single timing curve when calibrating the engine. This
means that the timing is not completely optimized for most modes of operation.
4.1.3 Marinization
Gasoline sterndrive and inboard (SD/I) engines are generally derived from land-based
counterparts. Engine marinizers buy automotive engine blocks and modify them for use on
boats. Because of the good power/weight ratio of gasoline engines, most SD/I engines are not
modified to produce more power than the base engines were originally designed to produce. In
some airboat applications, aircraft engines are used.
4.1.3.1 Typical SD/I marinization process
Marine SI engines are typically built from base engines designed for use in cars and
trucks. Currently, the vast majority of base engines are General Motor (GM) engines that range
in size from a 3.0 L in-line four cylinder engine to an 8.1 liter V8 engine and range in power
from about 100 to 300 kW. These engines are sold without front accessory drives or intake and
exhaust manifolds. Also, no carbureted versions of these engines are offered; they are either
sold with electronic fuel injection, or no fuel system at all. Relatively small numbers of custom
blocks and Mazda rotary engines are also used.
Marinizers convert the base engines into marine engines in the following ways:
- Choose and optimize the fuel management system.
- Configure a marine cooling system.
- Add intake and exhaust manifolds, and accessory drives and units.
Fuel and air management: Historically, Marine SI engines have been carbureted. Today
this technology seems to be going away but is still offered as cheaper alternative to electronic
fuel injection. Less than half of new engines are sold with carburetors. GM does not offer
carburetors or their associated intake manifolds because they are not used in the higher volume,
automotive applications. Therefore, marinizers who produce carbureted engines must purchase
the fuel systems and intake manifolds elsewhere.
The 3.0 L and 4.3 L base engines are offered with throttle body fuel injection systems as
an option. All of the larger engines are offered with multi-port fuel injection as an option.
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Feasibility of Exhaust Emission Control
Although GM offers a base marine calibration for its electronic control module, it also offers
software allowing marinizers to perform their own engine calibrations. For most engines sold,
the marinizers will alter the calibrations to optimize engine operation. Except for some small
market niches, the marinizers do not calibrate the engines for more power.
Cooling system: Marine SI engines are generally packaged in small compartments
without much air flow for cooling. In addition, Coast Guard safety regulations require that
surface temperatures be kept cool on the engine and exhaust manifold. Typically, marine
exhaust systems are designed with surface temperatures below 93°C (200°F). To do this,
manufacturers use ambient (raw) water to cool the engine and exhaust. Most sterndrive and
inboard engines use raw water to cool the engine. This water is then used, in a water jacket, to
cool the exhaust manifold. Finally, the water is dumped into the exhaust stream.
Most Marine SI engines are cooled with raw water. This means that ambient water is
pumped through the engine, to the exhaust manifold, and mixed with the exhaust. The
exhaust/water mixture is then dumped under water. Mixing the water with exhaust has three
advantages:
- cools the exhaust and protects rubber couplings in sterndrives
- acts as a muffler to reduce noise
- helps tune the exhaust back pressure
An alternative to raw water cooling is fresh water cooling. In a fresh water system, raw
water is used to cool the recirculated engine coolant ("fresh water"). The raw water is generally
still used to cool the exhaust manifold and exits the engine with the exhaust. However, some
systems use the engine coolant to cool the exhaust manifold.
Some gasoline engines, mostly inboards, have fresh water cooling systems which
provides two advantages. 1) Engine corrosion problems are reduced, especially when the boat is
used in saltwater. Fresh water systems keep saltwater, which can be corrosive, out of the engine.
Because salt emulsifies at about 68°C, thermostats in fresh water systems are set around 60-
62°C. 2) Marinizers can achieve much better control of the engine temperature. By reducing
variables in engine operation, combustion can be better optimized.3
There are trade-offs with using a fresh water system. The fresh water system costs more
because of the added pump and heat exchanger. Also, this system is not as efficient for cooling
the engine as pumping raw water directly to the engine
Other additions: As mentioned above, marinizers add intake manifolds to carbureted
engines. As part of the cooling system, marinizers must add water jacketed exhaust manifolds,
pumps, and heat exchangers. SD/I engines may also have larger oil pans to help keep oil
temperatures down. Because of the unique marine engine designs, marinizers also add their own
front accessory drive assembly. Finally, sterndrive engines also must be coupled with the lower
drive unit.
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4.1.3.2 High performance SD/I marinization process
There is a niche in the SD/I market where customers are willing to sacrifice engine
durability for a high power to weight ratio. Marinizers who address this niche do so by
increasing the fueling of the engine, optimizing the spark-timing for power, increasing the peak
engine speed (rpm), and modifying the exhaust manifold for better tuning. In some cases, the
marinizers may actually increase the displacement of the engine by boring out the cylinders.
Other components such as cam rails and pistons may also be modified. Superchargers may also
be added. As an example, GM's largest base engine for this market is rated at 309 kW. One
high performance SD/I engine with a bored cylinder, a high performance fuel injection
calibration, and a supercharger achieves more than 800 kW.
4.1.4 Gaseous Fuels
Engines operating on LPG or natural gas carry compressed fuel that is gaseous at
atmospheric pressure. The technical challenges for gasoline related to an extended time to
vaporize the fuel do not apply to gaseous-fuel engines. Typically, a mixer introduces the fuel
into the intake system. Manufacturers are pursuing new designs to inject the fuel directly into
the intake manifold. This improves control of the air-fuel ratio and the combustion event, similar
to the improvements in gasoline injection technology.
4.2 General Description of Exhaust Emission Control Technologies
HC and CO emissions from spark-ignition engines are primarily the result of poor in-
cylinder combustion. This is intensified in carbureted two-stroke engines with the very high HC
emissions due to short-circuiting losses. Higher levels of NOx emissions are the result of leaner
air-fuel ratios and the resulting higher combustion temperatures. Combustion chamber
modifications can help reduce HC emission levels, while using improved air-fuel ratio and spark
timing calibrations, as discussed in Sections 4.1.2.1 and 4.1.2.2, can further reduce HC emissions
and lower CO emissions. The conversion from carburetor to electronic fuel injection will also
help reduce HC and CO emissions. Exhaust gas recirculation could be used to reduce NOx
emissions. The addition of secondary air into the exhaust can significantly reduce HC and CO
emissions. Finally, the use catalytic converters can further reduce all three emissions.
4.2.1 Combustion chamber design
Unburned fuel can be trapped momentarily in crevice volumes (especially the space
between the piston and cylinder wall) before being released into the exhaust. Reducing crevice
volumes decreases this amount of unburned fuel, which reduces HC emissions. One way to
reduce crevice volumes is to design pistons with piston rings closer to the top of the piston. HC
may be reduced by 3 to 10 percent by reducing crevice volumes, with negligible effects on NOx
emissions.4
HC emissions also come from lubricating oil that leaks into the combustion chamber.
The heavier hydrocarbons in the oil generally do not burn completely. Oil in the combustion
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Feasibility of Exhaust Emission Control
chamber can also trap gaseous HC from the fuel and prevent it from burning. For engines using
catalytic control, some components in lubricating oil can poison the catalyst and reduce its
effectiveness, which would further increase emissions over time. To reduce oil consumption,
manufacturers can tighten tolerances and improve surface finishes for cylinders and pistons,
improve piston ring design and material, and improve exhaust valve stem seals to prevent
excessive leakage of lubricating oil into the combustion chamber.
4.2.2 Fuel injection
Fuel injection has proven to be an effective and durable strategy for controlling emissions
and reducing fuel consumption from highway gasoline engines. Comparable upgrades are also
available for gaseous fuels. This section describes a variety of technologies available to improve
fuel metering.
Throttle-body gasoline injection: A throttle-body system uses the same intake manifold
as a carbureted engine. However, the throttle body replaces the carburetor. By injecting the
fuel into the intake air stream, the fuel is better atomized than if it were drawn through with a
venturi. This results in better mixing and more efficient combustion. In addition, the fuel can be
more precisely metered to achieve benefits for fuel economy, performance, and emission control.
Throttle-body designs have the drawback of potentially large cylinder-to-cylinder
variations with multi-cylinder engines. Like a carburetor, TBI injects the fuel into the intake air
at a single location upstream of all the cylinders. Because the air-fuel mixture travels different
routes to each cylinder, and because the fuel "wets" the intake manifold, the amount of fuel that
reaches each cylinder will vary. Manufacturers account for this variation in their design and may
make compromises such as injecting extra fuel to ensure that the cylinder with the leanest
mixture will not misfire. These compromises affect emissions and fuel consumption.
Port gasoline injection: As the name suggests, port (single cylinder) or multi-port (multi-
cylinder-port) fuel injection means that a fuel injector is placed in close proximity to each of the
intake ports. The intake manifold, if used, flows only air. Sequentially-timed systems inject a
quantity of fuel each time the intake valve opens for each cylinder, but multi-port injection
systems can also be "batch fired" (all injectors pulsed simultaneously on a multicylinder engine)
or continous (e.g., the Bosch CIS automotive systems of the 1970's and 80's). Port injection
allows manufacturers to more precisely control the amount of fuel injected for each combustion
event. This control increases the manufacturer's ability to optimize the air-fuel ratio for
emissions, performance, and fuel consumption. Because of these benefits, multi-port injection is
has been widely used in automotive applications for decades.
Sequential injection has further improved these systems by more carefully timing the
injection event with the intake valve opening. This improves fuel atomization and air-fuel
mixing, which further improves performance and control of emissions.
A newer development to improve injector performance is air-assisted fuel injection. By
injecting high pressure air along with the fuel spray, greater atomization of the fuel droplets can
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Draft Regulatory Impact Analysis
occur. Air-assisted fuel injection is especially helpful in improving engine performance and
reducing emissions at low engine speeds. In addition, industry studies have shown that the short
burst of additional fuel needed for responsive, smooth transient maneuvers can be reduced
significantly with air-assisted fuel injection due to a decrease in wall wetting in the intake
manifold. On a highway 3.8-liter engine with sequential fuel injection, the air assist was shown
to reduce HC emissions by 27 percent during cold-start operating conditions. At wide-open-
throttle with an air-fuel ratio of 17, the HC reduction was 43 percent when compared with a
standard injector.5
4.2.3 Exhaust gas recirculation
Exhaust gas recirculation (EGR) has been in use in cars and trucks for many years. The
recirculated gas acts as a diluent in the air-fuel mixture, slowing reaction rates and absorbing
heat to reduce combustion temperatures. These lower temperatures can reduce the engine-out
NOx formation rate by as much as 50 percent.6 HC is increased slightly due to lower
temperatures for HC burn-up during the late expansion and exhaust strokes.
Depending on the burn rate of the engine and the amount of recirculated gases, EGR can
improve fuel consumption. Although EGR slows the burn rate, it can offset this effect with
some benefits for engine efficiency. EGR reduces pumping work of SI engines because the
addition of nonreactive recirculated gases forces larger throttle openings for the same power
output. Because the burned gas temperature is decreased, there is also less heat loss to the
exhaust and cylinder walls. In effect, EGR allows more of the chemical energy in the fuel to be
converted to useable work.7
Electronic EGR control: Many EGR systems in today's automotive applications utilize a
control valve that requires vacuum from the intake manifold to regulate EGR flow. Under part-
throttle operation where EGR is needed, engine vacuum is sufficient to open the valve.
However, during throttle applications near or at wide-open throttle, engine vacuum is too low to
open the EGR valve. While EGR operation only during part-throttle driving conditions has been
sufficient to control NOx emissions for vehicles in the past, more stringent NOx standards and
emphasis on controlling off-cycle emission levels may require more precise EGR control and
additional EGR during heavy throttle operation to reduce NOx emissions. Automotive
manufacturers now use electronic control of EGR. By using electronic solenoids to directly
open and close the EGR valve or by modulating the vacuum signal to vacuum actuated valves,
the flow of EGR can be precisely controlled.
Stratified EGR. Another method of increasing the engine's tolerance to EGR is to
stratify the reicirculated gases in the cylinder. This stratification allows high amounts of dilution
near the spark plug for NOx reduction while making undiluted air available to the crevices, oil
films, and deposit areas so that HC emissions may be reduced. Stratification may be induced
radially or laterally through control of air and mixture motion determined by the geometry of the
intake ports. Research on a one cylinder engine has shown that stratified EGR will result in
much lower fuel consumption at moderate speed and load (6 percent EGR at 2400 rpm, 2.5 bar
BMEP) while maintaining low HC and NOx emissions when compared to homogeneous EGR.8
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Feasibility of Exhaust Emission Control
For catalyst systems with high conversion efficiencies, the benefit of using EGR becomes
proportionally smaller, although it can offer cost savings by reducing catalyst rhodium loadings.
Including EGR as a design variable for optimizing the engine can add significantly to the
development time needed to fully calibrate the electronic controls of engines or vehicles.
4.2.4 Multiple valves and variable valve timing
Four-stroke engines generally have two valves for each cylinder, one for intake of the air-
fuel mixture and the other for exhaust of the combusted mixture. The duration and lift (distance
the valve head is pushed away from its seat) of valve openings is constant regardless of engine
speed. As engine speed increases, the aerodynamic resistance to pumping air in and out of the
cylinder for intake and exhaust also increases. Automotive engines have started to use two
intake and two exhaust valves to reduce pumping losses and improve their volumetric efficiency
and useful power output.
In addition to gains in volumetric efficiency, four-valve designs allow the spark plug to
be positioned closer to the center of the combustion chamber, which decreases the distance the
flame must travel inside the chamber. This decreases the likelihood of flame-quenching
conditions in the areas of the combustion chamber farthest from the spark plug. In addition, the
two streams of incoming gas can be used to achieve greater mixing of air and fuel, further
increasing combustion efficiency and lowering engine-out emissions.
Control of valve timing and lift take full advantage of the four-valve configuration for
even greater improvement in combustion efficiency. Engines normally use fixed-valve timing
and lift across all engine speeds. If the valve timing is optimized for low-speed torque, it may
offer compromised performance under higher-speed operation. At light engine loads, for
example, it is desirable to close the intake valve early to reduce pumping losses. Variable-valve
timing can enhance both low-speed and high-speed performance with less compromise.
Variable-valve timing can allow for increased swirl and intake charge velocity, especially during
low-load operating conditions where this is most problematic. By providing a strong swirl
formation in the combustion chamber, the air-fuel mixture can mix sufficiently, resulting in a
faster, more complete combustion, even under lean air-fuel conditions, thereby reducing
emissions. Automotive engines with valve timing have also replaced external EGR systems with
"internal EGR" accomplished via variable valve overlap, generally with improved EGR rate
control over external systems and improved engine-out NOx emissions.
4.2.5 Secondary air
Secondary injection of air into exhaust ports or pipes after cold start (e.g., the first 40-60
seconds) when the engine is operating rich, coupled with spark retard, can promote combustion
of unburned HC and CO in the exhaust manifold and increase the warm-up rate of the catalyst.
By means of an electrical or mechanical pump, or by using a passive venturi or check-valve,
secondary air is injected into the exhaust system, preferably in close proximity of the exhaust
valve. Together with the oxygen of the secondary air and the hot exhaust components of HC and
CO, net oxidizing conditions ahead of the catalyst can bring about an efficient increase in the
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Draft Regulatory Impact Analysis
exhaust temperature which helps the catalyst to heat up quicker. The exothermic reaction that
occurs is dependent on several parameters (secondary air mass, location of secondary air
injection, engine A/F ratio, engine air mass, ignition timing, manifold and headpipe construction,
etc.), and ensuring reproducibility demands detailed individual application for each vehicle or
engine design.
Secondary air injection was first used as an emission control technique in itself without a
catalyst, and still is used for this purpose in many highway motorcycles and some off-highway
motorcycles to meet federal and California emission standards. For motorcycles, air is usually
provided or injected by a system of check valves which uses the normal pressure pulsations in
the exhaust manifold to draw in air from outside, rather than by a pump.9
Secondary air injection can also be used in continuous operation with rich-jetted
carbureted engines to a achieve an exhaust chemistry just rich of stoichiometry to improve the
efficiency of 3-way catalysts.10'11
4.2.6 Catalytic Aftertreatment
Over the last several years, there have been tremendous advances in exhaust
aftertreatment systems. Catalyst manufacturers have increased the use of palladium (Pd),
particularly for close-coupled positions in automotive catalyst applications.12 Improvements to
catalyst thermal stability and washcoat technologies, the design of higher cell densities, and the
use of two-layer washcoat applications are just some of the advances made in catalyst
technology.13 Current Pd catalysts are capable of withstanding prolonged exposure to
temperatures approaching 1100°C.14 The light-off temperature of these advanced catalysts is in
the range of 250 to 270°C.
There are two types of catalytic converters commonly used: oxidation and three-way.
Oxidation catalysts use platinum and/or palladium to increase the rate of reaction between
oxygen in the exhaust and unburned HC and CO. Ordinarily, this reaction would proceed very
slowly at temperatures typical of engine exhaust. The effectiveness of the catalyst depends on its
temperature, on the air-fuel ratio of the mixture, and on the mix of HC present. Highly reactive
species such as formaldehyde and olefins are oxidized more effectively than less-reactive
species. Short-chain paraffins such as methane, ethane, and propane are among the least reactive
HC species, and are more difficult to oxidize.
Three-way catalysts use a combination of platinum and/or palladium and rhodium. In
addition to promoting oxidation of HC and CO, these metals also promote the reduction of NO to
nitrogen and oxygen. In order for the NO reduction to occur efficiently, an overall rich or
slightly-rich of stoichiometric air-fuel ratio is required. The NOx efficiency drops rapidly as the
ai-fuel ratio becomes leaner than stoichiometric. If the air-fuel ratio can be maintained precisely
at or just rich of stoichiometic, a three-way catalyst can simultaneously oxidize HC and CO and
reduce NOx. The window of air-fuel ratios within which this is possible is very narrow and
there is a trade-off between NOx and HC/CO control even within this window. The window can
be broadened somewhat through the use of oxygen storage components, such as cerium oxide,
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Feasibility of Exhaust Emission Control
within the catalyst washcoating. Cerium oxide also promotes CO and HC removal via steam
reformation with water vapor in the exhaust, and the hydrogen liberated by these reactions
promotes further NOx reduction.
Manufacturers are developing catalysts with substrates that utilize thinner walls in order
to design higher cell density, low thermal mass catalysts for close-coupled applications
(improves mass transfer at high engine loads and increase catalyst surface area). The cells are
coated with washcoat which contain the noble metals which perform the catalysis on the exhaust
pollutants. The greater the number of cells, the more surface area with washcoat that exists,
meaning there is more of the catalyst available to convert emissions (or that the same catalyst
surface area can be put into a smaller volume). Cell densities of 900 cells per square inch (cpsi)
have already been commercialized, and research on 1200 cpsi catalysts has been progressing.
Typical cell densities for conventional automotive catalysts are 400 to 600 cpsi.
There are several issues involved in designing catalytic control systems for the engines
covered by this proposal. The primary issues are the cost of the system, packaging constraints,
and the durability of the catalyst. This section addresses these issues.
4.2.6.1 System cost
Sales volumes of recreational vessels are small compared to automotive sales and while
sales of Small SI engines <19kW are similar, the price of equipment is much less than
automotive. Manufacturers therefore have a limited ability to recoup large R&D expenditures
for these applications. For these reasons, we believe it is not appropriate to consider highly
refined catalyst systems that are tailored specifically to nonroad applications. Catalyst
manufacturers have assured us that automotive-type catalysts can easily be built to any size
needed for Small SI and marine applications. We are considering catalyst packaging designs
that does not require the manufactures to incur the costs of reworking the entire exhaust system
and, for Marine SI engines, the lower power unit. The cost of these systems will decrease
substantially when catalysts become commonplace. Chapter 6 describes the estimated costs for a
nonroad catalyst systems for Small SI and Marine SI engines.
4.2.6.2 Differences in emission control system application and design by engine
category
One challenge in the use of catalytic control for Small SI and Marine SI engines lies in
acceptable design and packaging of the exhaust catalysts onto a wide variety of different types of
equipment. This section discusses specific issues related to these applications.
4.2.6.2.1 Small SI Class I engines
Class I engines typically are equipped with integral exhaust and fuel systems and are
air-cooled. Significant applications include walk-behind lawn mowers (largest segment),
pressure washers, generator sets and pumps. There are both overhead valve (OHV) and
side-valve (SV) engines used in Class I, but side-valve engines are the predominant type in Class
4-13
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Draft Regulatory Impact Analysis
I, particularly in lawn mower applications. They currently represent about 60 percent of Class I
sales. Exhaust catalyst design for Class I engines must take into account several important
factors that differ from automotive applications:
1. Air-cooled engines run rich of stoichiometry to prevent overheating when under load.
Because of this, CO and HC emissions can be high. Catalyst induced oxidation of a high
percentage of available reactants in the exhaust in the presence of excess oxygen (i.e.,
lean of stoichiometric conditions) can result in highly exothermic exhaust reactions and
increase heat rejection from the exhaust. For example, approximately 80 to 90 percent of
the energy available from catalyst-promoted exhaust reactions is via oxidation of CO.
2. Air-cooled engines have significant HC and NOx emissions that are typically much
higher on a brake-specific basis than water-cooled automotive engine types. Net heat
available from HC oxidation and NOx reduction at rich of stoichiometric conditions is
considerably less than that of oxidation of CO at near stoichiometric or lean of
stoichiometric conditions due to the much lower concentrations of NO and HC in the
exhaust relative to CO.
3. Most Class I engines do not have 12-volt DC electrical systems to power auxiliaries and
instead are pull start. Electronic controls relying on 12-volt DC power would be difficult
to integrate onto Class I engines without a significant cost increase.
4. Most Class I engines use inexpensive stamped mufflers with internal baffles. Mufflers
are typically integrated onto the engine and may or may not be placed in the path of
cooling air from the cooling fan.
5. The regulatory emission test cycles (A-cycle, B-cycle), manufacturer's durability cycles
and some limited in-use operation data indicate that emissions control should focus
primarily on light and part load operation for the highest volume applications
(lawnmowers).
These factors would lead to exhaust catalyst designs for small engines that should differ
somewhat from those of light duty gasoline vehicle exhaust catalyst designs. Design elements
specific to Class I Phase 3 exhaust catalysts would include:
1. Catalyst substrate volume would be sized relatively small so as to be space-velocity
limited. Catalyst volume for Class I Phase 3 engines would be approximately 18 to 50
percent of the engine cylinder displacement, depending on cell count, engine-out
emission levels, and oil consumption. Catalyst substrate sizes would be compact, with
typical catalyst substrate volumes of approximately 2 to 5 cubic inches. This would
effectively limit mass transport to catalyst sites at moderate-to-high load conditions and
reduce exothermic reactions occurring when exhaust temperature is highest. This is
nearly the opposite of the case of typical automotive catalyst designs. Automotive
catalyst volume is typically 50 to 100 percent of cylinder displacement, with the chief
constraints on catalyst volume being packaging and cold-start light-off performance.
2. Catalyst precious metal loading (Pt-platinum, Pd-palladium, Rh-rhodium) would be kept
relatively low, and formulations would favor NOx and HC selectivity over CO
selectivity. We estimate that typical loading ratios for Phase 3 would be approximately
in the range of 40 to 50 g/ft3 (approximately 50 percent of typical automotive loadings at
4-14
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Feasibility of Exhaust Emission Control
light-duty vehicle Tier 2 emission levels) and can be Pt:Rh, Pd:Rh or tri-metallic.
Tri-metallic platinum group metal (PGM) loadings that replace a significant fraction of Pt
with Pd would be less selective for CO oxidation and would also reduce the cost of the
catalyst. Loading ratios would be similar or higher in Rh than what is typically used for
automotive applications (20-25 percent of the total PGM mass in Small SI) to improve
NOx selectivity, improve rich of stoichiometry HC reactions and reduce CO selectivity.
3. Catalysts would be integrated into the muffler design. Incorporating the catalyst into the
muffler would reduce surface temperatures, and would provide more surface area for heat
rejection. This is nearly the opposite of design practice used for automotive systems,
which generally try to limit heat rejection to improve cold-start light-off performance.
The muffler design for Class I Phase 3 engines would have somewhat higher surface area
and somewhat larger volume than many current Class I muffler designs in order to
promote exhaust heat rejection and to package the catalyst, but would be similar to some
higher-end "quiet" Class I muffler designs. Appropriately positioned stamped
heat-shielding and touch guards would be integrated into Class I Phase 3 catalyst-muffler
designs in a manner similar to many Class I Phase 2 mufflers. A degree of heat rejection
would be available via forced convection from the cooling fan, downstream of cooling
for the cylinder and cylinder head. This is the case with many current muffler designs.
Heat rejection to catalyst muffler surfaces to minimize "hot spots" can also be enhanced
internally by turning the flow through multiple chambers and baffles that serve as sound
attenuation within the muffler, similar to the designs used with catalyst-equipped lawn
mowers sold in Sweden and Germany.
4. Many Class I Phase 3 catalysts would include passive secondary air injection to enhance
catalyst efficiency and allow the use of smaller catalyst volumes. Incorporation of
passive secondary air allows halving of catalyst substrate volume for the same catalyst
efficiency over the regulatory cycle. A system for Class I Phase 3 engines would be sized
small enough to provide minimal change in exhaust stoichiometry at high load conditions
so as to limit heat rejection, but would be provide approximately 0.5 to 1.0 points of
air-to-fuel ratio change at conditions of 50 percent of peak torque and below in order to
lower HC emissions effectively in engines operating at air-to-fuel ratios similar to those
of current Class I Phase 2 engines. Passive secondary air systems are preferred.
Mechanical or electrical air pumps are not necessary. Passive systems include stamped
or drawn Venturis or ejectors integrated into the muffler, some of which may incorporate
an air check-valve, depending on the application. Pulse-air injection is also a form of
passive secondary air injection. Pulse air draws air into the exhaust port through a
check-valve immediately following the closure of the exhaust valve. Active secondary
air (air pump) systems were not considered in this analysis since they may be cost
prohibitive for use in Class I applications due to the need for a mechanical accessory
drive or 12-volt DC power.
5. Catalyst durability in side valve engines can be enhanced through two catalyst design
ideas. First, the use of a pipe catalyst upstream of the main catalyst brick can "catch" the
oil in the exhaust thereby limiting the amount seen in the catalyst and thereby catalyst
poisoning. Second, the catalyst brick can be lengthened to allow poisoning to some
degree yet allow for catalyst conversion for the regulatory life of the engine.
6. Class I engines are typically turned off via a simple circuit that grounds the input side of
4-15
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Draft Regulatory Impact Analysis
the ignition coil. Temperature fail-safe capability could, if appropriate, be incorporated
into the engine by installing a bimetal thermal switch in parallel with the ignition
grounding circuit used for turning the engine off. The switch can be of the inexpensive
bimetal disc type in wide-spread use in numerous consumer products (furnaces,
water-heaters, ovens, hair dryers, etc.). To reduce cost, the bimetal switch could be a
non-contact switch mounted to the engine immediately behind the muffler, similar to the
installation of bimetal sensors currently used to actuate automatic chokes on current
Phase 2 Class I lawn mower engines.
4.2.6.2.2 Small SI Class II engines
Almost all Class II engines are air-cooled. Unlike Class I engines, Class II engines are
not typically equipped with integral exhaust systems and fuel tanks. Significant applications
include lawn tractors (largest segment), commercial turf equipment, generator sets and pumps.
Overhead valve engines have largely replaced side-valve engines in Class II, with the few
remaining side-valve engines certifying to the Phase II standards using emissions credits or
being used in snow thrower type applications where the HC+NOx standards do not apply. Class
II engines are typically built more robustly than Class I engines. They often use cast-iron
cylinder liners, may use either splash lubrication or full-pressure lubrication, employ high
volume cooling fans and in some cases, use significant shrouding to direct cooling air. Exhaust
catalyst design practice for Class II engines will differ depending on the level of emission
control. Class II engine designs are more suitable for higher-efficiency emission control systems
than most Class I engine designs. The design factors are somewhat similar to Class I:
1. Class II engines are mostly air-cooled, and thus must run rich of stoichiometry at high
loads. The ability to operate at air-to-fuel ratios rich of stoichiometry at high load may
be more critical for some Class II engines than for Class I engines due to the longer
useful life requirements in Class II. The larger displacement Class II engines have better
efficiency combustion and some engines incorporate more advanced fuel metering and
spark control than is typical in Class I, in order to meet the more stringent Class II Phase
2 emission standards (12.1 g/kW-hr HC+NOx in Class II versus 16.1 g/kW-hr in Class I).
The heat energy available from CO oxidation is typically somewhat less than the case in
Class I because of slightly lower average emission rates.
2. Class II engines have HC and NOx emissions that are generally in more equal portions,
or have the potential to be, in the total regulated HC+NOx emissions and lower CO
emissions than is the case for Class I engines.
3. Most Class II engines are equipped with 12-volt DC electrical systems for starting.
Electronic controls relying on 12-volt DC power could be integrated into Class II engine
designs. Low-cost electronic engine management systems are extensively used in motor
scooter applications in Europe and Asia. Both Kohler and Honda have introduced Class
II engines in North America that use electronic engine management systems.
4. Class II engines use inexpensive stamped mufflers with internal baffles similar to Class I,
but the mufflers are often not integrated onto the engine design and may be remote
mounted in a manner more typical of automotive mufflers. Class II mufflers are often not
placed in the direct path of cooling air from the cooling fan.
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Feasibility of Exhaust Emission Control
5. As with Class I, the regulatory cycles (A-cycle, B-cycle), manufacturer's durability cycles
and some limited in-use operation data indicate that emissions control should focus
primarily on light and part load operation for the high volume sales of garden tractor
equipment.
Taking these factors into account would point towards exhaust catalyst designs that differ
from those of light duty gasoline exhaust catalysts and differ in some cases from Class I systems.
Elements specific to Class II Phase 3 emission control system design using carburetor fuel
systems would include:
1. Catalyst substrate volume would be sized relatively small so as to be space-velocity
limited. Catalyst volume for Class II Phase 3 engines would be approximately 33-50
percent of the engine cylinder displacement, depending on cell count, engine-out
emission levels, oil consumption and the useful life hours to which the engine's emissions
are certified. Catalyst substrate sizes would be very compact within typical mufflers used
in Class II, with typical catalyst substrate volumes of approximately 8 to 10 cubic inches
(based on sales weighting within useful life categories). This would effectively limit
mass transport to catalyst sites at moderate-to-high load conditions and reduce
exothermic reactions occurring when exhaust temperature is highest.
2. Catalyst precious metal loading would be kept relatively low, and formulations would
favor NOx and HC selectivity over CO selectivity to minimize heat concerns. We
estimate that typical loading ratios for Phase 3 would be approximately in the range of 30
to 50 g/ft3 (approximately 50 percent of typical automotive loadings) and could be Pt:Rh,
Pd:Rh or tri-metallic. Tri-metallic PGM loadings that replace a significant fraction of Pt
with Pd would be less selective for CO oxidation and would also reduce the cost of the
catalyst. Loading ratios would be similar or higher in Rh than what is typically used for
automotive applications (20-25 percent of the total PGM mass in Small SI).
3. Catalysts would be integrated into the muffler design. Incorporating the catalyst into the
muffler would reduce surface temperatures relative to the use of a separate catalyst
component. The catalyst for Class II Phase 3 engines would be integrated into mufflers
that are similar in volume to today's Class II Phase 2 mufflers. Appropriately positioned
stamped heat-shielding and touch guards would be integrated into Class II Phase 3
catalyst-muffler designs in a manner similar to current product. Class II engines typically
have a much higher volume of cooling air available downstream of the cylinder than
Class I engines. Heat rejection from the cylinder and cylinder head increases the
temperature of the cooling air, but it is still sufficiently below the temperature of exhaust
system components to allow its use for forced cooling. Thus a degree of heat rejection
would be available via forced convective cooling of exhaust components via the cooling
fan. However, this would require some additional ducting to supply cooling air to exhaust
system surfaces along with careful layout of engine and exhaust components within the
design of the equipment that it is used to power. Integrated catalyst-mufflers can also use
exhaust energy for ejector cooling (see chapter 6). Heat rejection to catalyst muffler
surfaces to minimize "hot spots" can also be enhanced internally by turning the flow
through multiple chambers and baffles that serve as sound attenuation within the muffler.
4. Some applications may include secondary air injection to enhance catalyst efficiency.
4-17
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Draft Regulatory Impact Analysis
Incorporation of passive secondary air allows halving of catalyst substrate volume for the
same catalyst efficiency over the regulatory cycle. In many cases, this may not be
necessary due to the lower engine-out emissions of Class II engines. In cases where
secondary air is used, it could either be a passive system similar to the previously
described Class I systems, or an active system with an engine driven pump. Pump drive
for active systems could be either 12-volt DC electric or via crankcase pulse, and pump
actuation could be actively controlled using an electric solenoid or solenoid valve. The
use of active systems is an option but seems unlikely. The most likely control scenario
for Class II would be a combination of engine out emission control, use of a small
catalyst, and no use of secondary air.
Higher catalyst efficiency, considerably lower exhaust emissions levels, and improved fuel
consumption are possible with Class II engines, but heat rejection and safety considerations
might necessitate the use of electronic engine management and open-loop fuel injections
systems. In such a case, the design and integration of the emission control system would more
closely resemble automotive applications with the use of electronic engine management and
larger catalyst volumes with higher precious metal loadings.
4.2.6.2.3Marine SI
Due to the design of marine exhaust systems, fitting a catalyst into the exhaust system
raises unique application issues for many boat/engine designs. Often boat builders will strive to
minimize the space taken up in the boat by the engine compartment. In addition, these exhaust
systems are designed, for safety reasons, to avoid hot surface temperatures. For most Marine SI
engines, the surface temperature is kept low by running raw water through a jacket around the
exhaust system. This raw water is then mixed with the exhaust before being passed out of the
engine. To avoid a major redesign of the exhaust system, the catalyst must be placed upstream
of where the water and exhaust mix. In addition, the catalyst must be insulated and/or water-
jacketed to keep the surface temperatures of the exhaust low.
As discussed later in this chapter,
testing has been performed on prototype
systems where small catalysts have been placed
in the exhaust manifolds of SD/I engines.
Figure 4.2-1 illustrates one installation design.
For outboard engines, this packaging
arrangement would be less straightforward
because of the very short exhaust path between
the cylinder exhaust ports and where the
cooling water and exhaust mix. However, it
may be possible to engineer a packaging
solution for outboards as well similar to that
shown for SD/I in Figure 4.2-1.
Several marine engine manufacturers
Figure 4.2-1: Placement of Marine Catalyst
4-18
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Feasibility of Exhaust Emission Control
are now producing engines with water jacketed catalysts in the exhaust. As discussed later in
this chapter, one manufacturer has certified personal watercraft engines with catalysts packaged
in the exhaust system. These are small oxidation catalysts used in conjunction with two-stroke
engines. Two manufacturers are selling marine generators with catalysts. Also, one SD/I engine
marinizer has recently added an engine with catalysts in the exhaust to its product line.
Another issue is maintaining high enough temperatures with a water-jacketed catalyst for
the catalyst to react properly. The light-off temperature of these advanced catalysts is in the
range of 250 to 270°C which was low enough for the catalysts to work effectively in our
laboratory tests. However, it could be necessary for manufacturers to retard the spark timing at
idle and low load for some engines to maintain this minimum temperature in the catalyst.
The matching of the catalyst to the engine may have to be compromised to fit it into the
exhaust manifold. However, significant reductions are still achievable. One study on a 4.3 liter
automotive engine looked at three different Pd-only catalyst displacements. The smallest of
these catalysts had a displacement ratio of 0.12 to 1. The HC+NOx downstream of the catalyst
was measured to be from 1.2 to 2.6 grams per mile, depending on the severity of the catalyst
aging.15 This is equivalent to about 1.5 to 3.2 g/kW-hr based on highway operation.16 This work
suggests that significant reductions are achievable with an "undersized" catalyst. As discussed
later in this chapter, significant reductions in exhaust emissions have been demonstrated for
catalysts packaged in SD/I exhaust systems.
4.2.6.3 Catalyst Durability
Two aspects of marine applications that could affect catalyst durability are thermal load
and vibration. Because the catalyst would be coupled close to the exhaust ports, it would likely
see temperatures as high as 750 to 850°C when the engine is operated at full power. The bed
temperature of the catalyst would be higher due to the reactions in the catalyst. However, even
at full power, the bed temperature of the catalyst most likely would not exceed the exhaust
temperature by more than 50-100°C. In our laboratory testing, we minimized the temperature at
full load by operating the engine with a rich air-fuel mixture. The temperatures seen were well
within the operating range of new Pd-only catalysts which are capable of withstanding prolonged
exposure to temperatures approaching 1100°C.17
In on-highway applications, catalysts are designed to operate in gasoline vehicles for
more than 100,000 miles. This translates to about 4,000-5,000 hours of use on the
engine/catalyst. We estimate that, due to low annual hours of operation, the average useful life
of Small SI and Marine SI engines is only a fraction percent of this value. This suggests that
catalysts designed for automotive use should be durable over the useful life of a Small SI and
Marine SI engines. Use of catalysts in automotive, motorcycle, and hand-held equipment
applications suggests that catalysts can be packaged to withstand the vibration in the exhaust
manifold. As discussed later in this chapter, catalysts have recently been demonstrated, through
in-use testing, to be durable over the useful lives of SD/I marine vessels.
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Draft Regulatory Impact Analysis
4.2.6.4 Water Reversion
Another aspect of marine applications that could affect catalyst durability is the effect of
water contact with the catalyst. There is concern that, in some designs, water could creep back
up the exhaust passages, due to pressure pulses in the exhaust, and damage the catalyst and
oxygen sensor. This damage could be due to thermal shock from cold water coming into contact
with a hot catalyst or due to salt deposition on the catalyst. One study was performed, using a
two-stroke outboard equipped with a catalyst, to investigate the effect of water exposure on a
catalyst.18 The results of this study are summarized in Table 4.2-1.
Table 4.2-1: Summary of Marine Catalyst Durability Study
Issue
high catalyst
temperatures
saltwater effects
fresh water effects
thermal shock of hot
catalyst with cold
water
deterioration factor
Investigation
- compared base catalyst to catalysts aged for 10
hrs at 900 and 1050°C
- soaked catalysts in two seawater solutions and
compared to base catalyst
- used intake air with a salt-water mist
- soaked catalyst in fresh water and compared to
base catalyst
- flushed out catalyst with fresh water that was
soaked in saltwater
- as part of the catalyst soaking tests, 900°C
catalysts were soaked in both salt and fresh
water
- operated engine with catalyst for 300 hours of
E4 operation
Result
- little change in conversion efficiency
observed
- large drop in conversion efficiency
observed
- no effect on catalyst
- little change in conversion efficiency
observed
- washing catalyst removes salt and
restores some performance
- no damage to the catalysts was
reported
- 20% loss in conversion efficiency for a
2-stroke engine
The above study on catalysts in marine applications was performed supplemental to an
earlier study.19 The earlier study also showed that immersing the catalysts in saltwater would
hurt the conversion efficiency of the catalyst, but that operating in a marine environment would
not. In addition, this earlier study showed that much of the efficiency loss due to salt on the
catalyst could be reversed by flushing the catalyst with water. This paper also showed that with
the catalyst activated, temperatures at full power were less than at mid power because the space
velocity of the exhaust gases at rated speed was high enough to reduce the conversion efficiency
of the catalyst.
A study of water reversion was performed on a vessel powered by a sterndrive engine.20
However, it was found that the water found in the exhaust system upstream of where the exhaust
and water mix was due to condensation. This condensation was a result of cool surfaces in the
exhaust pipe due to the water-jacketing of the exhaust. This study found that the condensation
could be largely resolved by controlling the exhaust cooling water temperature with a thermostat.
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Feasibility of Exhaust Emission Control
Since that time, data has been collected on a number of catalyst-equipped SD/I vessels operated
either in salt or fresh-water. This data, which showed no significant catalyst deterioration, is
discussed later in this chapter. These engines were designed to prevent water reversion by
placing the catalyst near the engine and away from the water/exhaust mixing point. In addition,
some of the prototype designs used either a water dam or mist barrier to help limit any potential
water reversion.
4.2.7 Advanced Emission Controls
On February 10, 2000, EPA published new "Tier 2" emissions standards for all passenger
vehicles, including sport utility vehicles (SUVs), minivans, vans and pick-up trucks. The new
standards will ensure that exhaust VOC emissions be reduced to less than 0.1 g/mi on average
over the fleet, and that evaporative emissions be reduced by at least 50 percent. Onboard
refueling vapor recovery requirements were also extended to medium-duty passenger vehicles.
By 2020, these standards will reduce VOC emissions from light-duty vehicles by more than 25
percent of the projected baseline inventory. To achieve these reductions, manufacturers will
need to incorporate advanced emission controls, including: larger and improved close-coupled
catalysts, optimized spark timing and fuel control, improved exhaust systems.
To reduce emissions, gasoline-fueled vehicle manufacturers have designed their engines
to achieve virtually complete combustion and have installed catalytic converters in the exhaust
system. In order for these controls to work well for gasoline-fueled vehicles, it is necessary to
maintain the mixture of air and fuel at a nearly stoichiometric ratio (that is, just enough air to
completely burn the fuel). Poor air-fuel mixture can result in significantly higher emissions of
incompletely combusted fuel. Current generation highway vehicles are able to maintain
stoichiometry by using closed-loop electronic feedback control of the fuel systems. As part of
these systems, technologies have been developed to closely meter the amount of fuel entering the
combustion chamber to promote complete combustion. Sequential multi-point fuel injection
delivers a more precise amount of fuel to each cylinder independently and at the appropriate time
increasing engine efficiency and fuel economy. Electronic throttle control offers a faster
response to engine operational changes than mechanical throttle control can achieve, but it is
currently considered expensive and only used on some higher-price vehicles. The greatest gains
in fuel control can be made through engine calibrations — the algorithms contained in the
powertrain control module (PCM) software that control the operation of various engine and
emission control components/systems. As microprocessor speed becomes faster, it is possible to
perform quicker calculations and to increase response times for controlling engine parameters
such as fuel rate and spark timing. Other advances in engine design have also been used to
reduce engine-out emissions, including: the reduction of crevice volumes in the combustion
chamber to prevent trapping of unburned fuel; "fast burn" combustion chamber designs that
promote swirl and flame propagation; and multiple valves with variable-valve timing to reduce
pumping losses and improve efficiency. These technologies are discussed in more detail in the
RIA for the Tier 2 FRM.21
As noted above, manufacturers are also using aftertreatment control devices to control
emissions. New three-way catalysts for highway vehicles are so effective that once a TWC
4-21
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Draft Regulatory Impact Analysis
reaches its operating temperature, emissions are virtually undetectable.22 Manufacturers are now
working to improve the durability of the TWC and to reduce light-off time (that is, the amount of
time necessary after starting the engine before the catalyst reaches its operating temperature and
is effectively controlling VOCs and other pollutants). EPA expects that manufacturers will be
able to design their catalyst systems so that they light off within less than thirty seconds of
engine starting. Other potential exhaust aftertreatment systems that could further reduce cold-
start emissions are thermally insulated catalysts, electrically heated catalysts, and HC adsorbers
(or traps). Each of these technologies, which are discussed below, offer the potential for VOC
reductions in the future. There are technological, implementation, and cost issues that still need
to be addressed, and at this time, it appears that these technologies would not be a cost-effective
means of reducing nonroad emissions on a nationwide basis.
Thermally insulated catalysts maintain sufficiently high catalyst temperatures by
surrounding the catalyst with an insulating vacuum. Prototypes of this technology have
demonstrated the ability to store heat for more than 12 hours.23 Since ordinary catalysts typically
cool down below their light-off temperature in less than one hour, this technology could reduce
in-use emissions for vehicles that have multiple cold-starts in a single day. However, this
technology would have less impact on emissions from vehicles that have only one or two cold-
starts per day.
Electrically-heated catalysts reduce cold-start emissions by applying an electric current to
the catalyst before the engine is started to get the catalyst up to its operating temperature more
quickly.24 These systems require a modified catalyst, as well as an upgraded battery and
charging system. These can greatly reduce cold-start emissions, but could require the driver to
wait until the catalyst is heated before the engine would start to achieve optimum performance.
Hydrocarbon adsorbers are designed to trap VOCs while the catalyst is cold and unable
to sufficiently convert them. They accomplish this by utilizing an adsorbing material which
holds onto the VOC molecules. Once the catalyst is warmed up, the trapped VOCs are
automatically released from the adsorption material and are converted by the fully functioning
downstream three-way catalyst. There are three principal methods for incorporating an adsorber
into the exhaust system. The first is to coat the adsorber directly on the catalyst substrate. The
advantage is that there are no changes to the exhaust system required, but the desorption process
cannot be easily controlled and usually occurs before the catalyst has reached light-off
temperature. The second method locates the adsorber in another exhaust pipe parallel with the
main exhaust pipe, but in front of the catalyst and includes a series of valves that route the
exhaust through the adsorber in the first few seconds after cold start, switching exhaust flow
through the catalyst thereafter. Under this system, mechanisms to purge the adsorber are also
required. The third method places the trap at the end of the exhaust system, in another exhaust
pipe parallel to the muffler, because of the low thermal tolerance of adsorber material. Again a
purging mechanism is required to purge the adsorbed VOCs back into the catalyst, but adsorber
overheating is avoided. One manufacturer who incorporates a zeolite hydrocarbon adsorber in
its California SULEV vehicle found that an electrically heated catalyst was necessary after the
adsorber because the zeolite acts as a heat sink and nearly negates the cold start advantage of the
adsorber. This approach has been demonstrated to effectively reduce cold start emissions.
4-22
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Feasibility of Exhaust Emission Control
4.3 Feasibility of Small SI Engine Standards
We are proposing new, more stringent HC+NOx standards for Small SI engines (<19kW)
used in nonhandheld, terrestrial applications (we are also proposing a CO std for Small SI
engines used in marine applications that is discussed in Section 4.4). The standards differ by
engine size. Class I engines have a total cylinder displacement of < 225cc. Class II engines
have a total displacement of >225cc. We are also proposing changes to the emission
certification protocols for durability testing and test fuel specifications for both classes. The new
certification requirements will improve emissions performance of these engines over their
regulatory lifetime and better align the test fuel with in-use fuel characteristics.
Table 4.3-1 shows the present Phase 2 exhaust emission standards for Class I and II small
spark ignition engines as well as the proposed Phase 3 standards. The proposed standards
represent a nominal 35-40 percent reduction from current standards.
Table 4.3-1: Comparison of Phase 2 and Proposed
Phase 3 Standards for Small Spark-Ignition Engines
Engine Class
Class I (<225 cc)
Class II (>225cc)
Current Phase 2
Standards
(HC+NOx g/kW-hr)
16.1
12.1
Proposed Phase
Standards
(HC+NOx g/kW-hr)
10.0
8.0
Percent Reduction
(%)
38
34
The following sections present the technical analyses and information that support our
view that the proposed Phase 3 exhaust emission requirements are technically feasible. We
begin with a review of the current state of compliance with the Phase 2 standards relative to the
proposed standards and conclude with a more in depth assessment of the technical feasibility of
the proposed requirements for Class I gasoline-fueled engines, Class II single-cylinder gasoline-
fueled engines, Class II multi-cylinder gasoline-fueled engines, and both classes of gaseous-
fueled (e.g., liquid propane gas) engines.
4.3.1 Current Technology and 2005 Certification Test Data
In the 2005 model year manufacturers certified engines to the Phase 2 standards using a
variety of engine designs and emission control technology. Table 4.3-2 shows manufacturers'
projected engine sales by technology type. For Class I engines, side-valve designs represent the
majority of sales, although there are also a significant number of overhead-valve sales. An
extremely small number of engines used catalyst-based emission control technology. Class II is
dominated by overhead-valve engine designs. A limited number of these engines used catalyst
technology, electronic fuel injection, or were water cooled.
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Draft Regulatory Impact Analysis
Table 4.3-2: 2005 Engine Sales by Technology Market Mix
Engine Technology
Side Valve
Overhead Valve
With Catalyst
With Other (Electronic Fuel
Injection and/or water cooled)
Class I
60%
40%
0.04%
0
Class II
2%
98%
0.2%
2%
Looking at the industry from an engine family rather than a sales perspective, shows that
75 and 136 engine families were emission certified in Class I and II, respectively for 2005. The
range of technology types is shown in Table 4.3-3. The most of engine families in Class I are
overhead-valve, carbureted engines, with only six families using side-valve, carbureted designs
(the side-valve engines still account for the bulk of Class I sales). Four families utilized catalytic
exhaust aftertreatment.
Table 4.3-2: 2005 Small Spark-Ignition
Engine Technology Types and Number of Engine Families
Engine
Class
Class I
Class II
Side-Valve
Single-
Cylinder
Carburet
or
yes (5)
yes (4)
Single-
Cylinder
Carburet
or w.
Catalyst
yes(l)
yes(l)
Overhead Valve
Single-
Cylinder
Carburet
or
yes (66)
yes (67)
Single-
Cylinder
Carburet
or w.
Catalyst
yes (3)
no
Multi-
Cylinder
Carburet
or
no
yes (58)
Multi-
Cylinder
Fuel
Injection
no
yes (2)
Multi-
Cylinder
Fuel
Injection
w.
Catalyst
no
yes (4)
In Class II, about half of the engine families are overhead-valve, carbureted,
single-cylinder designs. Based on Table 4.3-2, these families dominate the sales in this class.
None of these carbureted families used a catalyst. There are several single-cylinder engine
families using the older, less sophisticated side-valve technology. One of these uses a catalyst.
Also, about half of this class is comprised of engine families that use multi-cylinder
(predominately v-twins) designs incorporating overhead-valve technology. Most of these
multi-cylinder families utilized carburetors, with a few using fuel injection and electronic engine
controls. Several of these engine families use catalytic aftertreatment.
Figures 4.3-1 and 4.3-2 present the 2005 certification results at full life for Class I and 2
4-24
-------
Feasibility of Exhaust Emission Control
engine families, respectively, by technology type. In both cases, several engine families were
certified at levels necessary to comply with the proposed Phase 3 standards. A number of
families are very close to the requisite emission levels. This suggests that, even accounting for
the relative increase in stringency associated with our proposed certification protocols, a number
of families will either not need to do anything or require only modest reductions in their
emission performance to meet the proposed standards.
4-25
-------
Draft Regulatory Impact Analysis
Figure 4.3-1: Class I HC+NOx Full Life Certification Results
.c
§ 12
> 12
s 10.
X
O
£ 6
2 -
1C
Class I HC+NOx CLs 2005 MY
•
•
• ...
1 : ' . i t
<• . • I' • ' * {•
•::••• I
^m -^ |
+. gv carb g
• OHV carb
A OHV catalyst A
Phase 2
- - • Phase 3
A
30 110 120 130 140 150 160 170 180 190 2(
Displacement [cc]
I
30
Figure 4.3-2: Class II HC+NOx Full Life Certification Results
oc
9n -
k.
.C
§ 1^;
S
x
o 10 .
Z IU
+
o
c;
(
Class II HC+NOx CLs 2005 MY
^ SVcarb
X SV catalyst
• OHV carb
* • OHV fuel inj.
* A OHV catalyst
Phase ?
** ---Phases
3vCr ^ • * " "
, „ , . .SH?f •• fc-"M- - *r *P- - - - -•- - -
*™ r ^ • rm ^ v •
• M A
A A
) 200 400 600 800 1000 1200 1400
Displacement [cc]
4-26
-------
Feasibility of Exhaust Emission Control
4.3.2 Technology Assessment and Demonstration
As described above, a number of engine families already are certified to emission levels
that likely would comply with the proposed Phase 3 standards. However, many engine families
clearly will have to do more to improve emission performance. Generally, we believe the
proposed requirements will require many engine manufacturers to adopt exhaust aftertreatment
technology using catalyst-based systems. Other likely changes include improved engine designs
and fuel delivery systems. Finally, adding electronic controls or fuel injection systems may
obviate the need for catalytic aftertreatment for some engine families, with the most likely
candidates being multi-cylinder engine designs.
Many of the technical design considerations for adapting advanced emission controls to
Small SI engines were presented in Section 4.2. These included redirected air from the cooling
fan, redirected exhaust flow through multiple chamber and baffles within the catalyst muffler, or
other design considerations. (These are also the kinds of design elements that engine
manufacturers will need to consider for safe and durable emission control systems.) In the
remainder of this section we describe the specific results of our emission control assessment
based on engine testing of exhaust catalyst systems, as well as a more specific discussion of
other potential emission reduction technology for certain engine types such as electronic engine
controls and fuel injection. The results of our safety assessment are described later in section 4.8
of this chapter.
4.3.2.1 Overview of Technology Assessment
Our feasibility assessment began by evaluating the emissions performance of current
technology for Small SI engines and equipment. These initial efforts focused on developing a
baseline for emissions and general engine performance so that we could assess the potential for
new emission standards for engines and equipment in this category. This process involved
laboratory and field evaluations of the current engines and equipment. We reviewed engineering
information and data on existing engine designs and their emissions performance. We also
reviewed patents of existing catalyst/muffler designs for Class I engines. We engaged engine
manufacturers and suppliers of emission control-related engine components in discussions
regarding recent and expected advances in emissions performance beyond that required to
comply with the current Phase 2 standards. Finally, we purchased catalyst/muffler units that
were already in mass production by an original equipment manufacturer for use on European
walk-behind lawn mowers and conducted engineering and chemical analysis on the design and
materials of those units.
We used the information and experience gathered in the above effort along with the
previous catalyst design experience of our engineering staff to design and build prototype
catalyst-based emission control systems that were capable of effectively and safely achieving the
proposed Phase 3 requirement based on dynamometer and field testing. We also used the
information and the results of our engine testing to assess the potential need for improvements to
engine and fuel system designs, and the selective use of electronic engine controls and fuel
injection on some engine types. A great deal of this effort was conducted in association with our
4-27
-------
Draft Regulatory Impact Analysis
more exhaustive study regarding the efficacy and safety of implementing advanced exhaust
emission controls on Small SI engines, as well as new evaporative requirements for these
engines.25 In other testing, we evaluated advanced emission controls on a multi-cylinder Class II
engine with electronic fuel injection.26
In designing our engine testing program, we selected engines certified to the Phase 2
emission standards that were expected to remain compliant with those standards for the duration
of their useful life based on our low-hour emission testing and the manufacturer's declared
deterioration factor from the certification records for that engine family. We also selected
engine families that represented: 1) a cross section of Class I and Class II side-valve and
overhead-valve technologies; and 2) higher sales volume families. Each engine was maintained
based on the manufacturer's specifications.1 The results of our specific technical feasibility
assessment are presented below.
4.3.2.2 Class I Gasoline-Fueled Engines
We tested six side-valve and six overhead-valve Class I engines that used gasoline fuel
with prototype catalyst/muffler control systems. The primary design target for selecting the
catalyst configuration, e.g., volume, substrate, platinum group metal (PGM), was to achieve
emission levels below the proposed limit of 10 g/kW-hr HC+NOx for this class at 125 hours of
engine operation. That time period represents the useful life requirement for the most common
application in this category, i.e., residential walk-behind lawn mowers. A maximum of about 7
g/kW-hr HC+NOx was set as the low-hour performance target with a catalyst system to allow for
engine and emission control degradation over the engine's useful life. This level assumes a
certification cushion at low hours of 1 g/kW-hr HC+NOx and a multiplicative deterioration
factor of 1.3. Secondary design targets were primarily safety related and included minimizing
CO oxidation at moderate to high load conditions to maintain exhaust system surface
temperatures comparable to those of the original Phase 2 compliant systems. The test engine,
size, and salient catalyst features are shown in Table 4.3-4.
Table 4.3-5 presents the results of our catalyst testing on Class I engines.27'28 Three of the
engines were tested at high hours. The high-hour results for the remaining engines were
projected from their low-hour emission performance. We projected high-time emission results
for these engines by applying the multiplicative deterioration factor from the manufacturer's
Phase 2 certification application to the low-hour emission test results. The certification
deterioration factors ranged from 1.097 to 1.302 g/kW-hr HC+NOx. As shown, each of the
engines achieved the requisite emission limit of 10 g/kW-hr HC+NOx at the end of their useful
lives.
1 The specific test engines were generally used in residential lawn mower and lawn tractor applications.
These applications were chosen for field testing as part of our safety study because they represented certain
potentially unique and challenging safety concerns connected with operation and storage in environments with
combustible debris.
4-28
-------
Table 4.3-4: Class I Test Engine and Control Technology Description
Engi
ne
ID
236
246
248
249
6820
258
241
255
2982
243
244
245
Displace
ment
(L)
0.20
0.20
0.20
0.20
0.19
0.19
0.19
0.19
0.19
0.16
0.16
0.16
Valve
Train
Side
Side
Side
Side
Side
Side
Overh
ead
Overh
ead
Overh
ead
Overh
ead
Overh
ead
Overh
ead
Fuel
Meteri
ng
Carbur
etor
Carbur
etor
Carbur
etor
Carbur
etor
Carbur
etor
Carbur
etor
Carbur
etor
Carbur
etor
Carbur
etor
Carbur
etor
Carbur
etor
Carbur
etor
Passive
(Ventu
ri)
Second
ary
Air?
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Catalyst Type
Metal monolith
Metal monolith
Metal monolith
Wire-mesh
Cordierite
Ceramic
Monolith
Cordierite
Ceramic
Monolith
Cordierite
Ceramic
Monolith
Coated tube
pre-catalyst,
Metal monolith
main-body
catalyst
Metal monolith
Cordierite
Ceramic
Monolith
Metal monolith
Metal monolith
Catalyst
Volume
44 cc
44 cc
44 cc
60 cc
40 cc
40 cc
40 cc
20 mm dia.
X73mm
long exhaust
tubing, 22 cc
metal
monolith
34 cc
30 cc
44 cc
44 cc
Catalyst
Cell
Density
200
cpsi
200
cpsi
200
cpsi
N/A
400
cpsi
400
cpsi
400
cpsi
Tube: 2
channel
s
(annular
shape),
Main
body:
200
cpsi
100
cpsi
400
cpsi
200
cpsi
200
cpsi
PGM Loading
(mass/catalyst
volume,
Pt:Pd:Rh ratio)
30 g/ft3, 4:0:1
30 g/ft3, 4:0:1
30 g/ft3,
0.33:3.66:1
proprietary,
0:0:1
30 g/ft3, 5:0:1
30 g/ft3, 5:0:1
30 g/ft3, 5:0:1
Tube:
Proprietary
Main body: 30
g/ft3, 3:1:1
50 g/ft3, 5:0:1
30 g/ft3, 5:0:1
30 g/ft3, 1:3:1
30 g/ft3, 3:1:1
-------
Draft Regulatory Impact Analysis
Table 4.3-5: Class I Emission Results with Advanced Catalytic Control Technology
Engine
236
246
248
249
6820
258
241
255
2982
243
244
245
Age
(hours)1
10-20
Projected High
10-20
Projected High
10-20
Projected High
10-20
Projected High
Not Tested
>110
10-20
>110
10-20
>110
10-20
Projected High
10-20
>110
10-20
Projected High
10-20
Projected High
10-20
Projected High
HC+NOx
(g/kW-hr)
4.9±0.62
6.1
5.6
7.0
4.6
5.7
6.3
7.8
na
9.4
6.7
8.2
3. 9 ±0.2
6.6 ± 0.2
5.0
6.5
4.9 ±0.3
7.0 ± 0.4
7± 1
7.7
7.2
7.9
5.6
6.1
1 Projected high hour results estimated by multiplying the low hour test results by the
manufacturer's certification deterioration rate.
2 "±" values represent the 95% confidence intervals of 3 tests using a 2-sided t-test.
4-30
-------
Feasibility of Exhaust Emission Control
The above method for projecting high-hour emission results using a certification
deterioration factor assumes that the catalyst system will control engine-out emissions to the
same extent, i.e., proportional reduction, over the useful life of the engine. For some engines this
may not always be the case depending on oil consumption, air-to-fuel ratio and other factors that
may change the effectiveness of the catalyst over time.2 Our approach also did not explicitly
account for the fact that manufacturer's will generally design the engine and catalyst to provide
some certification cushion. It appears that most of the engines in Tables 4.3-5 would
accommodate the above design considerations. However, the projected high-time results are
uncomfortably close to the 10 g/kW-hr HC+NOx standard for engine number 6820. In these
cases, such factors can be accounted for by the engine manufacturer in the engine family's
research and design phase by either improving the durability of the engine (see the discussion
below) or designing the catalyst to account for necessary improvement in catalyst effectiveness
over time, e.g, more precious metal loading, larger catalyst volume, dividing the catalyst into
two separate pieces within the exhaust stream, etc.
The technical feasibility of the Phase 3 standard for Class I engines is supported by a
number of Small SI engine manufacturers.29'30'31'32 Also, a manufacturer of emission controls
specifically indicated the types of hardware that may be needed to comply with new standards.33
That manufacturer concluded that, depending on the application and engine family, either
catalyst or electronic engine controls should be able to achieve emission standards as low as 9
g/kW-hr HC+NOx. As demonstrated above, we believe the proposed standard of 10 g/kW-hr
HC+NOx can be achieved using catalysts only. However, based on our engineering judgment,
we agree that it may be possible to achieve the standard with the sole use of electronic engine
controls because of the more precise management of air-fuel mixtures and ignition spark timing
offered by that technology.
We conducted a design and process Failure Mode and Effects Analysis study to assess
the safety of implementing advanced exhaust emission controls on Small SI engines.34 That
work, which was based in part on our engine test program, suggests that manufacturers of Class I
may need to improve the durability of basic engine designs, ignition systems, or fuel metering
systems for some engines in order to comply with the emission regulations at full useful life.
Some of these emission-related improvements may include:
1. Adding a fuel filter or improving the needle and seat design in the carburetor to
minimize fuel metering problems caused by debris from the fuel tank;
2. Improving intake manifold design or materials to reduce air leaks;
3. Upgrading the ignition system design for better ignition spark reliability and
durability;
2 Catalyst performance degradation can occur from thermal sintering and catalyst poisoning due to oil
consumption. Catalyst performance can also improve as engine air-to-fuel ratio slowly drifts towards stoichiometry
over the useful life of the engine. Air-cooled engines are typically designed with air-to-fuel ratio calibrations that
take into account lean-drift with extended operation, and are designed with a sufficiently rich air-to-fuel ratio to
prevent net-lean operation at high hours that could result in engine damage or deteriorating engine performance.
4-31
-------
Draft Regulatory Impact Analysis
4. Improving design and manufacturing processes for carburetors to reduce the
production variability in air-fuel mixtures; and
5. Enhancing exhaust manifold design for better reliability and durability.
4.3.2.3 Class II Single-Cylinder Gasoline-Fueled Engines
Class II single-cylinder engines that use gasoline fuel are currently certified and sold
under the Phase 2 standard in both side-valve and overhead-valve configurations. In 2005, only
5 out of 78 Class II single-cylinder engine families used side-value designs. Manufacturers
certified these families under the averaging provisions of the applicable regulations with
emission credits that were generated by (low emitting) overhead-valve engines. We believe that
the proposed Phase 3 standard will reduce the number of emission credits available for the
certification of side-valve technology. As a result, we assume that a number of the remaining
Class II side-valve engines may be phased out of applicable manufacturer's product line in the
future.
Based on the above, we did not directly assess the technical feasibility of the proposed
standard for side-valve Class II engines in our test program. Instead we assessed only
single-cylinder, overhead-valve Class II engines with prototype catalyst/muffler control systems.
The primary design target for selecting the catalyst configuration for these engines, e.g., volume,
substrate, design and PGM loading, was to achieve emission levels well below the proposed
limit of 8 g/kW-hr HC+NOx for this class to accommodate the longer useful life of many of
these engines. (The emission regulations allow useful lives ranging from 250 tolOOO hours.)
For two of the engines families, we selected emission control technology with a target of
meeting a 3.5 g/kW-hr HC+NOx. This included the use of electronic engine and fuel controls to
improve the management of air-fuel mixtures and ignition spark timing that allow, among other
advantages, the use of larger catalyst volumes and higher precious metal loading. Secondary
design targets were primarily safety related and included minimizing CO oxidation at moderate
to high load conditions to maintain exhaust system surface temperatures comparable to those of
the original Phase 2 compliant systems. The test engines, size, salient catalyst parameters, and
use of electronic engine controls are shown in Table 4.3-6.
4-32
-------
Feasibility of Exhaust Emission Control
Table 4.3-6: Class II Single-Cylinder Test Engine and Control Technology Description
Engine
142
231
251
253
232
Displace
ment
(L)
0.40
0.50
0.50
0.50
0.49
Valve
Train
Overhead
Overhead
Overhead
Overhead
Overhead
Fuel
Metering
Carburetor
Electronic
Fuel
Injection
Carburetor
Carburetor
Electronic
Fuel
Injection
Catalyst
Type
Cordierite
Ceramic
Monolith
Metal
monolith
Cordierite
Ceramic
Monolith
Cordierite
Ceramic
Monolith
Metal
monolith
Catalyst
Volume
250 cc
280 cc
250 cc
250 cc
250 cc
Catalyst
Cell
Density
400 cpsi
200 cpsi
400 cpsi
400 cpsi
200 cpsi
Catalyst Loading
40 g/ft3, 5:0:1'
70 g/ft3, 0:5:1
40 g/ft3, 5:0:1
40 g/ft3, 5:0:1
40 g/ft3, 5:0:1
1 Metal loading expressed as a ratio of platinum:paladium:rodium.
Table 4.3-7 shows the results of our catalyst testing on single cylinder Class II engines.
Only one of the engines was tested at high hours. As explained above for the Class I engines,
the high-hour results for the remaining engines were projected from their low-hour emission
performance. We projected high-time emission results for these engines by applying the
multiplicative deterioration factor from the manufacturer's Phase 2 certification application to the
low-hour emission test results. The certification deterioration factors ranged from 1.033 to 1.240
g/kW-hr HC+NOx. As shown, each of the engines achieved the requisite emission limit of 8
g/kW-hr HC+NOx.
4-3
-------
Draft Regulatory Impact Analysis
Table 4.3-7: Class II Single-Cylinder Emission Results
with Advanced Catalytic Control Technology
Engine
231
232
251
253
142
Age
(hours)1
10-40
Projected High
10-40
Projected High
10-40
Projected High
10-40
Projected High
50
500
HC+NOx
(g/kW-hr)
1.8±0.42
2.2
2.2±0.1
2.3
3.1 ±.3
3.8
4.5 ±0.1
5.6
2.5 ±0.6
2.8
1 Projected high-hour results estimated by multiplying the low-hour test results by the manufacturer's
2004 certification deterioration rate.
2 "±" values represent the 95% confidence intervals of 3 tests using a 2-sided t-test.
Again, as with Class I engines, the technical feasibility of the Class II standard was
supported by a number of Small SI engine manufacturers.35363738 Also, a manufacturer of
emission controls specifically indicated the types of hardware that may be needed to comply
with new standards.39 That manufacturer concluded that, depending on application and engine
family, a catalyst and electronic engine controls should be capable of achieving emission
standards as low as 7 g/kW-hr HC±NOx. Also, as described above, that same manufacturer
concluded that, again depending on the application and engine family, either catalyst or
electronic engine controls should be able to achieve emission standards as low as 9 g/kW-hr
HC±NOx. Our proposed standard of 8 g/kW-hr HC±NOx is in between these two regions.
Therefore, based solely on that manufacturer's conclusions, complying with the proposed
standard may require control technology ranging from either a catalyst or electronic engine
controls, or a combination of both.
Based on the above information, especially our testing as discussed previously, we
conclude that catalysts do not necessarily need to be used in conjunction with electronic engine
controls to achieve our proposed standard of 8 g/kW-hr HC±NOx. Either one of those
technologies appear sufficient. In fact, market forces may cause some manufacturers to shift to
electronic controls in the absence of more stringent emission standards. Nonetheless, we can not
discount the possibility that both technologies may be used by some manufacturers to meet the
proposed standard on single-cylinder Class II engines. (See section 4.2.3.4 for more on
electronic engine control and fuel injection.)
The design and process Failure Mode and Effects Analysis study mentioned previously
suggests that manufacturers of Class II may need to improve the durability of basic engine
4-34
-------
Feasibility of Exhaust Emission Control
designs, ignition systems, or fuel metering systems for some engines in order to comply with the
emission regulations at full useful life.40 Some of these emission-related improvements may
include:
1. Reducing the variability in air-fuel mixtures with tighter manufacturing tolerances for
fuel metering components; and
2. Improving the ignition system design for better ignition spark reliability and
durability.
4.3.2.4 Class II Multi-Cylinder Gasoline-Fueled Engines
Gasoline-fueled Class II multi-cylinder engines are very similar to their single-cylinder
counterparts. Beyond the difference in the number of cylinders, several more Class II multi-
cylinder engine families are currently certified with catalysts and electronic engine control
technology (either with or without a catalyst). Because of the direct similarities and the use of
more sophisticated emission control-related technology on some engine families, we find that
our conclusions regarding the technical feasibility of the proposed 8 g/kW-hr HC+NOx standard
for single-cylinder Class II engines is directly transferable to multi-cylinder Class II engines.
Nonetheless, we also tested two twin-cylinder gasoline-fueled Class II engines from
different engine families by the same manufacturer.41 The engines were basically identical
except for their fuel metering systems, i.e., carbureted or electronic fuel injection. We tested
both without modification and tested the electronic fuel injected engine with a catalyst system
that we developed. All the tests were conducted when the engines had accumulated 10-15 total
hours of operating time.
The results of this testing are shown in Table 4.3-8. As was done for the Class I and II
single-cylinder engines discussed earlier, we projected emission levels at the end of each
engine's useful life using the multiplicative deterioration factors for each engine family as
reported in the manufacturer's 2005 Phase 2 certification application. As shown, the carbureted
engine is projected to have end of life emissions of approximately 9.1 g/kW-hr. Based on our
experience with single-cylinder engines, compliance with the proposed standard may require the
use of a catalyst for this engine family. The unmodified engine with electronic fuel injection is
projected to achieve about 7.3 g/kW-hr. This engine is very close to complying with the
proposed standard and will most likely require only additional fuel-air mixture and injection
timing calibration changes for compliance.
4-35
-------
Draft Regulatory Impact Analysis
Table 4.3-8: Class II Multi-Cylinder
Emission Results with Advanced Catalytic Control Technology
(V-Twin, Approximately 0.7 Liter Displacement, 3-Way Catalyst)
Engine
Configu
r-ation
OEM
OEM
OEMw.
Fuel
Metering
Carburet
EFI
EFI
Age
(hours)1
10-40
Projected
10-40
Projected
10-40
Projected
HC+NO
X
(g/kW-
hr)
7.2
9.1
5.9
7.3
1.8
2.2
Catalyst Type
—
—
—
—
Cordierite
same
Cataly
st
Volu
me
—
—
—
—
700cc
same
Cataly
st Cell
Densit
y
—
—
—
—
400
same
Catalys
t
Loadin
g
—
—
—
—
60
same
1 Projected high-hour results estimated by multiplying the low-hour test results by the manufacturer's
2004 certification deterioration rate.
2 Metal loading expressed as a ratio of platinum:paladium:rodium.
Finally, the combination of electronic fuel injection and catalytic exhaust aftertreatment
clearly has the potential to reduce emission well below the proposed standard as shown in the
table.
We also evaluated emission control technology for twin-cylinder Class II engines, and by
analogy all multi-cylinder engines, as part of our safety study.42 Here again we did not find any
unique challenges in designing catalyst-based control systems for these multi-cylinder engines
relative to the feasibility of complying with the proposed exhaust standards under normal engine
operation. However, we did conclude that these engines may present unique concern with the
application of catalytic control technology under atypical operation conditions. More
specifically, the concern relates to the potential consequences of combustion misfire or a
complete lack of combustion in one of the two or more cylinders when a single catalyst/muffler
design is used. (A single muffler is typically used in Class II applications.) In a single-catalyst
system, the unburned fuel and air mixture from the malfunctioning cylinder would combine with
hot exhaust gases from the other, properly operating cylinder. This condition would create high
temperatures within the muffler system as the unburned fuel and air charge from the misfiring
cylinder combusts within the exhaust system. This could potentially destroy the catalyst.
One solution is simply to have a separate catalyst/muffler for each cylinder. Another
solution is to employ electronic engine controls to monitor ignition and either put the engine into
"limp-mode" or shut the engine down until the condition clears on re-start or until necessary
repairs are made, if appropriate. For engines using carburetors, this would effectively require the
addition of electronic controls. For engines employing electronic fuel injection that may need to
also employ a small catalyst, it would require that the electronic controls incorporate ignition
misfire detection if they do not already utilize the inherent capabilities within the engine
4-36
-------
Feasibility of Exhaust Emission Control
management system.
We expect some engine families will use electronic fuel injection to meet the proposed
Phase 3 standard without employing catalytic aftertreatment. As described earlier, engine
families that already use these fuel metering systems and are reasonably close to complying with
the proposed requirement are likely to need only additional calibration changes to the engine
management system for compliance. In addition, we expect that some engine families which
currently use carbureted fuel systems will convert directly to electronic fuel injection.
Manufacturers may adopt this strategy to couple achieving the standard without a catalyst and
realizing other advantages of using fuel injection such as easier starting, more stable and reliable
engine operation, and reduced fuel consumption. A few engine manufacturers have
confidentially confirmed their plans to use electronic fuel injection on some engine families in
the future as part of an engine management strategy in lieu of using catalysts.
Our evaluation of electronic fuel injection systems that could be used to attain the
proposed standard found that a rather simple, low cost system should be sufficient. We
demonstrated this proof of concept as part of the engine test program we conducted for our
safety study. In that program, we fitted two single-cylinder Class II engines with an electronic
control unit and fuel system components developed for Asian motor-scooters and small-
displacement motorcycles. The sensors for the system were minimized to included a throttle
position sensor, air charge temperature sensor, oil temperature sensor, manifold absolute
pressure sensor, and a crankshaft position sensor. This is in contrast to the original equipment
manufacturer (OEM) fuel injection systems currently used in some with two-cylinder Class II
engine applications that employ more sophisticated and expensive automotive-based
components.
Regarding the electronic control unit and fuel system components referenced above and
in previous sections, at least two small engine manufacturers have developed simplified,
compact, low-cost electronically controlled fuel injection systems for small motorcycles and
scooters.4344 One manufacturer has also developed a general purpose small engine with
electronic engine speed control technology that eliminates the need for a battery.4546 These
manufacturers have generally reported a number of benefits for these advanced systems,
including lower emissions and better fuel economy.
4.3.2.5 Class II Gaseous-Fueled Engines
Engine manufacturers and equipment manufacturers certify engines to run on liquid
propane gas (LPG) or compressed natural gas (CNG) in a number of applications including
indoor floor buffers which require low CO emissions. The technology to reduce emissions to the
Phase 3 levels is catalyst due the fact that most engines run closer to stoichiometry than gasoline
engines and further enleanment to reduce emissions may not be feasible. Due to the high
amount of NOx compared with HC, as seen from engine data in the certification database, the
catalysts may need to be designed to reduce NOx and oxidize a limited amount of CO. The
EPA 2005 Certification Database lists 8 multi-cylinder engine families in the Class II 500 useful
life category as having catalysts. Due to this fact, it is assumed that gaseous engines do not have
4-37
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Draft Regulatory Impact Analysis
the same concerns with multi-cylinder engines and catalysts as gasoline engines.
4.4 Feasibility of Outboard/Personal Watercraft Marine Engine Standards
Outboard and personal watercraft (OB/PWC) engines are subject to exhaust emission
standards which require approximately a 75 percent reduction in hydrocarbon emissions
compared to conventional carbureted, crankcase-scavenged two-stroke engines. Because of the
emission credit program included in these requirements, manufacturers are able to sell a mix of
old and new technology engines to meet the standards on average.
We are proposing new exhaust emission standards for OB/PWC engines based on the
emissions results achievable from the newer technology engines. These technologies have
primarily been two-stroke direct injection and four-stroke engine designs. For a few model
years, one manufacturer certified PWC engines with catalytic aftertreatment. This section
presents emission data for 2004 model year outboard and personal watercraft engines and
includes a description of the various emission control technologies used. In addition, the
possibility of using catalytic aftertreatment on OB/PWC engines is discussed.
4.4.1 2004 OB/PWC Certification Test Data
When engine manufacturers apply for certification to exhaust emission standards, they
submit exhaust emission test data. In the case of the OB/PWC engines, the emission standards
are based on the sum of hydrocarbons and oxides of nitrogen (HC+NOx). Manufacturers submit
emission test data on HC and NOx to demonstrate their emission levels. Although carbon
monoxide (CO) emissions are not currently regulated, manufacturers submit data on CO
emissions as well.
Three primary technologies are used on Marine SI engines: conventional two-stroke
engines, direct injection two-stroke engines, and four-stroke engines. Conventional two-stroke
engines are primarily carbureted, but larger engines may have indirect fuel injection systems as
well (IDI). Four stroke engines come in carbureted, throttle-body fuel injected (TBI), and multi-
port fuel injection (MPI) versions. These technologies are discussed in more detail in
Section 4.4.2.
4.4.1.1 HC+NOx Certification Data
Figure 4.4-1 presents HC+NOx certification levels for 2006 model year outboard engines
and compares this data to the existing and proposed exhaust emission standards. These
certification levels are based on test data over the ISO E4 duty cycle with an adjustment for
emissions deterioration over the regulatory useful life. The certification data set includes
engines well above and below the emission standard. Manufacturers are able to certify to the
standard by meeting it on average. In other words, clean engines generate emission credits
which offset the debits incurred by the engines emitting above the standard. Figure 4.4-2
presents only the data from engines that meet the 2006 standard. As shown in these figures, two-
stroke direct injection engines and four-stroke engines easily meet the 2006 standard.
4-38
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Feasibility of Exhaust Emission Control
Figure 4.4-1: 2006 MY Outboard HC+NOx Certification Levels
400
2s Carb
2s Dl
4s Carb
4s EFI
• Baseline
• EPA 2006
•Proposed
50 100 150
Rated Power [kW]
200
Figure 4.4-2: 2006 MY New Technology Outboard HC+NOx Certification Levels
0
0
50 100
Rated Power [kW]
150
200
2s Carb
2s Dl
4s Carb
4s EFI
• Baseline
• EPA 2006
•Proposed
4-39
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Draft Regulatory Impact Analysis
Figures 4.4-3 and 4.4-4 present similar data for personal watercraft engines. These
engines use similar technology, but the HC+NOx emissions are a little higher on average,
presumably due to higher average power densities for PWC engines. This difference in
emissions is reflected in the proposed HC+NOx standards.
Figure 4.4-3: 2006 MY Personal Watercraft HC+NOx Certification Levels
400 -,
ocn
"^ 300
?> ?50
2 200
X
150
O 100
I
50
n
(
I
I
*
% . . 4
•
^—
1^™«»»^^^ ^«^^^^^^^^^^^^^^^^^^^^^
^^~ ^^HW
) 50 100 150 2(
Rated Power [kW]
)0
• 2s Carb
• 2s Dl
A 2s Catalyst
• Ac. PFI
'to cn
• • • Baseline
EPA 2006
Proposed
Figure 4.4-4: 2006 MY New Technology PWC HC+NOx Certification Levels
50
45
40
"U1
•C 3
-------
Feasibility of Exhaust Emission Control
4.4.1.2 CO Certification Data
Although no exhaust emission standards for CO are currently in place for Marine SI
engines, the technological advances associated with the HC+NOx standards have resulted in
lower CO emissions for many engines. Figures 4.4-5 and 4.4-6 present reported CO exhaust
emission levels for certified outboard and personal watercraft engines. These engines use similar
technology as outboard engines and show similar emission results.
Figure 4.4-5: Reported CO Emission Levels for 2006 MY Outboard Engines
50 100 150
Rated Power [kW]
200
Figure 4.4-6: Reported CO Emission Levels for 2006 MY PWC Engines
BOO -,
500 -
•Z1 400 -
•^ "300
s
O onn
o
100 -
o
(
v
x
x*>
» * .
•
ft
^••» •
3 50 100 150 2(
Rated Power [kW]
30
• 2s Cart
• 2s Dl
£.s L/aiaiysT
• 4s EFI
Proposed
4-41
-------
Draft Regulatory Impact Analysis
4.4.2 OB/PWC Emission Control Technologies
This section discusses the how general technologies discussed above apply to outboard
and PWC applications and discusses specific OB/PWC technology.
4.4.2.1 Conventional Two-Stroke Engines
As discussed earlier in this chapter, hydrocarbon emissions from two-stroke engines are
primarily the result of short-circuiting losses where unburned fuel passes through the engine and
out the exhaust during cylinder charging. Even with an indirect injection system, the air and fuel
are mixed prior to entering the cylinder. Therefore, even though there is better metering of fuel
and air than with a carbureted engine, short-circuiting losses still occur. Because of the very rich
and cool conditions, little NOx is formed. As shown in Figures 4.4-1 and 4.4-2, HC emissions
can range from 100 to 400 g/kW-hr. CO is formed as a product of incomplete combustion. As a
result, CO emissions range from 200 to 500 g/kW-hr from these engines.
4.4.2.2 Direct Injection Two-Stroke Engines
The primary advantage of direct-injection (DI) for a two-stroke is that the exhaust gases
can be scavenged with fresh air and fuel can be injected into the combustion chamber after the
exhaust port closes. As a result, hydrocarbon emissions, fuel economy, and oil consumption are
greatly improved. Some users prefer direct-injection two-stroke engines over four-stroke
engines due to the higher power to weight ratio. Today, this technology is used on engines with
power ratings ranging from 35 to 220 kW. One manufacturer has recently stated its plans to
manufacture DI two-stroke engines as low as 7.4 kW.
Most of the DI two-stroke engines currently certified to the current OB/PWC emissions
standards have HC+NOx emissions levels somewhat higher than certified four-stroke engines.
These engines also typically have lower CO emissions due to the nature of a heterogeneous
charge. By injecting the fuel directly into a charge of air in the combustion chamber, localized
areas of lean air/fuel mixtures are created where CO is efficiently oxidized. PM emissions may
be higher for DI two-stroke engines than for four-stroke engines because oil is burned in the
combustion chamber and because of localized rich areas in the fuel injection stream.
Recently, one manufacturer has introduced a newer technology DI two-stroke engine that
has comparable HC+NOx emission results as many of the certified four-stroke engines.47 This
engine makes use of a low-pressure fuel injection nozzle that relies on high swirl to produce
uniform fuel flow rates and droplet sizes. Also, significant improvements have been made in oil
consumption. As with the older DI two-stroke designs, CO emissions are much lower than
comparable four-stroke engines. What is unique about this design is that the manufacturer has
reported lower PM emissions than for a comparable four-stroke engine.
4-42
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Feasibility of Exhaust Emission Control
4.4.2.3 Four Stroke Engines
Manufacturers currently offer four-stroke Marine SI engines with power ratings ranging
from 1.5 to 224 kW. These engines are available with carburetion, throttle-body fuel injection,
or multi-point fuel injection. Carbureted engines are offered from 1.5 to 60 kW while fuel
injected engines are offered from 22 to 224 kW. One manufacturer has stated that the fuel
injection systems are too expensive to use on the smaller engine sizes. Most of the four-stroke
outboard engines above 19 kW have HC+NOx emissions below 16 g/kW-hr and many have
emissions below 13 g/kW-hr. CO emissions for these engines range from 150 to 250 g/kW-hr.
Based on the certification data, whether the engine is carbureted or fuel injected does not have a
significant effect on combined HC+NOx emissions. For PWC engines, the HC+NOx levels are
somewhat higher. However, many of the four-stroke PWC engines are below 16 g/kW-hr. CO
emissions for these engines are similar as those for four-stroke outboards.
4.4.2.4 Catalysts
One manufacturer has certified two PWC
engine models with oxidation catalysts. One
engine model uses the oxidation catalyst in
conjunction with a carburetor while the other uses
throttle-body fuel injection. The engine with
throttle-body fuel injection has an HC+NOx
emission rate of 25 g/kW-hr which is significantly
below the EPA 2006 standard. In this application,
the exhaust system is shaped in such a way to
protect the catalyst from water and is nearly as
large as the engine (see Figure 4.4-7). We are not
aware of any efforts to develop a three-way
catalyst system for PWC engines.
Figure 4.4-7: PWC Engine with Catalyst
We are also not aware of any development
efforts to package a catalyst into the exhaust system of an outboard marine engine. In current
designs, water and exhaust are mixed in the exhaust system to help cool the exhaust and tune the
engine. Water often works its way up through the exhaust system because the lower end in
under water and due to pressure pulses. As discussed above, salt-water can be detrimental to
catalyst performance and durability. In addition, the lower unit of outboards are designed to be
as thin as possible to improve the ability to turn the engine on the back of the boat and to reduce
drag on the lowest part of the unit. Certainly, the success of packaging catalysts in sterndrive
and inboard boats in recent development efforts (see below) suggests that catalysts may be
feasible for outboards. However, this has not yet been demonstrated and significant
development efforts would be necessary.
4.5 Feasibility of Sterndrive/Inboard Marine Engine Standards
4-43
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Draft Regulatory Impact Analysis
We are proposing exhaust emission standards for spark-ignition sterndrive and inboard
(SD/I) engines. These proposed emission standards are supported by data collected on SD/I
engines equipped with catalysts. This section presents exhaust emission data from baseline SD/I
engines as well as data from SD/I engines equipped with lean calibrations, exhaust gas
recirculation, and catalytic control.
4.5.1 Baseline SD/I Emissions Data
The vast majority of SD/I engines are four-stroke reciprocating piston engines similar to
those used in automotive applications. The exceptions are small sales of air boats using aircraft
piston-type engines and at least one marinizer that uses rotary engines. More than half of the
new engines sold are equipped with electronic fuel injection while the rest still use carburetors.
The majority of the electronic fuel injection systems are multi-port injection; however, throttle-
body injection is also widely used, especially on smaller engines.
Table 4.5-1 presents baseline emissions for four-stroke SD/I engines built up from
automotive engine blocks.48'49'50'51'52'53'54 All these data were collected during laboratory tests
over the ISO E4 duty cycle. Five of these engines are carbureted, one uses throttle-body fuel
injection, and four use multi-port fuel injection. One of the multi-port fuel injected engines was
tested with three calibrations. Note that without emissions calibrations performed specifically
for low emissions, the HC+NOx emissions are roughly equal for the carbureted and fuel injected
engines. Using the straight average, HC+NOx from the carbureted engines is 15.6 g/kW-hr
while it is 16.0 g/kW-hr from the fuel injected engines (15.1 g/kW-hr if the low HC calibration
outlier is excluded).
4-44
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Feasibility of Exhaust Emission Control
Table 4.5-1: Baseline SD/I Exhaust Emission Data
Engine
#
1
2
3
4
5
6
7
8
9
9
9
10
11
Power
[kW]
79
91
121
153
158
167
196
159
185
181
191
219
229
Fuel Delivery System
carburetor
carburetor
carburetor
multi-port electronic fuel injection
carburetor
carburetor
carburetor
throttle -body fuel injection
multi-port electronic fuel injection
#9, low CO calibration
#9, low HC calibration
multi-port electronic fuel injection
multi-port electronic fuel injection
HC
[g/kW-hr]
11.2
4.4
8.5
4.9
7.3
8.0
4.4
2.9
5.2
5.8
3.3
4.7
2.7
NOx
[g/kW-hr]
8.0
13.9
6.0
11.7
6.0
5.7
10.3
8.7
9.7
11.7
18.2
9.4
13.1
CO
[g/kW-hr]
281
98
247
111
229
174
101
42
149
48
72
160
44
A distinct class of SD/I engines are the high-performance engines. These engines are
similar to SD/I engines except that they are designed for high power output at the expense of
engine durability. This high power output is typically achieved through higher fuel and air rates,
larger combustion chambers, and through higher peak engine speeds. In most cases, custom
engine blocks are used. Even in the engines that use an automotive block, few stock automotive
engine components are used. Table 4.5-2 presents emission data collected on five high-
performance engines.55'56'57
4-45
-------
Draft Regulatory Impact Analysis
Table 4.5-2: Baseline High Performance SD/I Exhaust Emission Data [g/kW-hr]
Engine #
1
2
3
4
5
Power
[kW]
391
550
634
778
802
Fuel Delivery System
multi-port electronic fuel injection
carburetor
multi-port electronic fuel injection,
supercharger
throttle-body fuel-injection, supercharger,
intercooler
multi-port electronic fuel injection,
supercharger
HC
14.7
13.2*
16.9
7.6
16.1
NOx
3.8
8.4
9.1
4.9
9.4
CO
243
253
135
349
102
BSFC
354
376
348
448
299
* may be higher, HC concentration at idle was out of measurement range
4.5.2 Exhaust Gas Recirculation Emission Data
We collected data on three engines over the ISO E4 marine test cycle with and without
the use of exhaust gas recirculation (EGR).58'59'60 The first engine was a 6.8 L Ford heavy-duty
highway engine. Although this was not a marine engine, it uses the same basic technology as
SD/I engines. The second and third engines were the 7.4 L and 4.3 L SD/I engines used in the
catalyst development described below. These engines are marinized versions of GM heavy-duty
highway engines. The baseline emissions from the 7.4 L engine are a little different than
presented below in the catalyst discussion because engine head was rebuilt prior to the catalyst
development work.
This test data suggests that, through the use of EGR on a SD/I marine engine, a 40-50
percent reduction in NOx (30-40 percent reduction in HC+NOx) can be achieved. EGR was not
applied at peak power in this testing because the throttle is wide open at this point and displacing
fresh air with exhaust gas at this mode of operation would reduce power. We also did not apply
EGR at idle because the idle mode does not contribute significantly to the cycle weighted NOx.
4-46
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Feasibility of Exhaust Emission Control
Table 4.5-3: Exhaust Emission Data Using EGR on the E4 Marine Duty Cycle
EGR Scenario
6.8 L Engine: baseline
with EGR
7.4 L Engine: baseline
with EGR
4.3 L Engine: baseline
with EGR
HC
[g/kW-hr]
2.7
2.7
4.5
4.5
4.9
4.2
NOx
[g/kW-hr]
13.4
7.1
8.4
4.8
11.7
5.3
CO
[g/kW-hr]
26.5
24.3
171
184
111
92
Power
[kW]
145
145
209
209
153
148
BSFC
[g/kW-hr]
326
360
349
356
329
350
4.5.3 Catalytic Control Emission Data
4.5.3.1 Engine Testing
In a joint effort with the California Air Resources Board (ARE), we contracted with
Southwest Research Institute to perform catalyst development and emission testing on a SD/I
marine engine.61 This test program was performed on a 7.4 L electronically controlled
Mercruiser engine with multi-port fuel injection. Figure 4.5-1 illustrates the three primary
catalyst packaging configurations used in this test program. The upper right-hand picture shows
a catalyst packaged in a riser extension which would be placed between the lower exhaust
manifold and the exhaust elbow. This riser had the same outer dimensions as the stock riser
extension produced by Mercury Marine. The upper left-hand picture shows a catalyst packaged
in the elbow. The lower picture shows a larger catalyst that was packaged downstream of the
exhaust elbow. All of these catalyst configurations were water jacketed to prevent high surface
temperatures.
4-47
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Draft Regulatory Impact Analysis
Figure 4.5-1: Three Catalyst Configurations Used in SD/I Test Program
Table 4.5-4 presents the exhaust emission results for the baseline test and three catalyst
packaging configurations. In each case a pair of catalysts were used, one for each exhaust
manifold. For the riser catalyst configuration, we tested the engine with two cell densities, 60
and 300 cells per square inch (cpsi), to investigate the effects of back-pressure on power. The
catalysts reduced in HC+NOx in the range of 42 to 77 percent and reduced CO in the range of 46
to 54 percent. There were no significant impacts on power, and fuel consumption actually
improved due to the closed-loop engine calibrations necessary to optimize the catalyst
effectiveness. At the full power mode, we left the engine controls in open-loop and allowed it to
operate rich to protect the catalysts from over-heating.
4-48
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Feasibility of Exhaust Emission Control
Table 4.5-4: Exhaust Emission Data on a 7.4 L SD/I Engine with Various Catalysts
Catalyst Scenario*
(cell density, volume, location)
baseline (no catalyst)
60 cpsi, 0.7 L, riser
300 cpsi, 0.7 L, riser
400 cpsi, 1. 3 L, elbow
200 cpsi, 1.7 L, downstream
HC
[g/kW-hr]
4.7
2.5
1.7
2.8
2.1
NOx
[g/kW-hr]
9.4
5.7
1.9
1.1
1.2
CO
[g/kW-hr]
160
81
87
81
83
Power
[kW]
219
214
213
217
221
BSFC
[g/kW-hr]
357
345
349
337
341
*Multiply volume by two for total catalyst volume per engine.
Additional reductions in HC+NOx and CO can be achieved by using EGR in addition to
a catalyst. However, the added benefit of EGR is small combined to the emission reductions
achieved by the catalysts. Regardless, the use of EGR could give manufacturers some flexibility
in the design of their catalyst. In the catalyst testing work described above on the 7.4 L SD/I
marine engine, each of the catalyst configurations were tested with and without EGR. Table
4.5-5 presents these test results.
Table 4.5-5: Exhaust Emission Data on a 7.4 L SD/I Engine with Catalysts and EGR
Catalyst Scenario*
(cell density, volume, location)
60 cpsi, 0.7 L, riser
300 cpsi, 0.7 L, riser
400 cpsi, 1.3 L, elbow
200 cpsi, 1.7 L, downstream
HC+NOx [g/kW-hr]
catalyst
8.2
3.6
3.9
o o
J.J
catalyst + EGR
6.8
2.8
3.3
2.5
CO [g/kW-hr]
catalyst
81
87
81
83
catalyst +
EGR
74
77
76
73
* Multiply volume by two for total catalyst volume per engine.
4.5.3.2 Freshwater Boat Testing
The catalyst testing described above was a first step in developing and demonstrating
catalysts that can reduce emissions from Marine SI engines. However, this program only looked
at catalysts operating in a laboratory. Additional efforts have been made to address issues with
using catalyst in marine applications by operating an engines in boats with catalysts. When the
California Air Resources Board finalized their catalyst-based emission standards for SD/I
engines, they agreed to further assessment of the durability of catalyst used in boats through
technology review.
4-49
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Draft Regulatory Impact Analysis
To that end, ARB, industry and the U.S. Coast Guard recently performed a cooperative
in-boat demonstration program designed to demonstrate the feasibility of using catalysts in SD/I
applications.62^63 This testing included four boats, two engine types, and four catalysts. The
catalysts were packaged in the exhaust emission manifold in such a way that they were water-
jacketed and capable of fitting within the existing boat design. Each of the boats were operated
by the U.S. Coast Guard for 480 hours on a fresh water lake. This service accumulation period,
which was intended to represent the useful life of typical SD/I engines, began in December of
2003 and was completed in September of 2004. Table 4.5-6 presents a description of the boats
that were used in the test program.
Table 4.5-6: Vessel Configurations for Full Useful Life Catalyst Testing
Boat
Inboard Straight-Drive Ski Boat
Inboard V-Drive Runabout
22 ft, Sterndrive Bowrider
19 ft. Sterndrive Runabout
Engine
5.7L, V-8
5.7L, V-8
5. 7 L, V-8
4.3 L, V-6
Catalyst
Type
metallic
ceramic
metallic
ceramic
Catalyst
Volume*
1.4 L
1.7L
1.4L
0.7 L
Catalyst Cell
Density
300 cpsi
400 cpsi
200 cpsi
400 cpsi
*Multiply volume by two for total catalyst volume per engine.
Exhaust emissions were measured for each catalyst before and after the durability
testing.64 No significant deterioration was observed on any of the catalysts. In fact, all of the 5.7
L engines were below the proposed standard of 5 g/kW-hr HC+NOx even after the durability
testing. Although the zero hour emissions for the 4.3 L engine were less than half of the
proposed HC+NOx standard, the final emissions for the 4.3 L engine were 15 percent above the
proposed HC+NOx standard. However, it should be noted that the 4.3L engine was determined
to have excessive fuel delivered to one cylinder bank and low compression in one of the
cylinders. These problems did not appear to be related to the catalyst installations and would
account for the increase in emissions even without catalyst deterioration. Once the calibration
on this engine was corrected, a level of 5 g/kW-hr HC+NOx was achieved. In addition, no
deterioration was observed in the oxygen sensors which were installed upstream of the catalysts.
Significant carbon monoxide emission reductions were achieved, especially at lower
power modes. At wide-open-throttle, the engines operated in open-loop to prevent the exhaust
valves from overheating. Additional reductions in CO could be achieved through better fuel air
ratio control. For instance, although the engines in this test program were fuel injected, batch
injections were used. In other words, all of the fuel injectors for each bank were firing at the
same time rather than timing the fuel injection with the valve timing for each individual cylinder.
Because of this strategy, the engine would need to be calibrated somewhat rich. The next
generation of electronics for these engines are expected to have more sophisticated control which
would allow for optimized timing for each fuel injector.
4-50
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Feasibility of Exhaust Emission Control
Table 4.5-7: Vessel Configurations for Full Useful Life Catalyst Testing
Boat
5.7 L engine
4.3 L engine
Inboard Straight-
Drive Ski Boat
Inboard V-Drive
Runabout
22 ft, Sterndrive
Bowrider
19 ft. Sterndrive
Runabout
Catalyst Aging
baseline (no catalyst)
baseline (no catalyst)
0 hours
480 hours
0 hours
480 hours
0 hours
480 hours
0 hours
480 hours*
HC
[g/kW-hr]
5.4
4.9
1.7
2.1
1.8
1.7
1.8
1.5
1.9
2.9
NOx
[g/kW-hr]
6.7
11.7
1.0
1.7
0.5
1.0
0.5
0.9
0.5
2.1
CO
[g/kW-hr]
193
111
100
117
87
102
74
93
106
116
* after calibration corrected
4.5.3.3 Saltwater Boat Testing
Two test programs were initiated to investigate the feasibility of using catalysts on boats
used in saltwater. In the first program, a small boat with a catalyst was operated over a set of
operation conditions, developed by industry, to represent the worst case conditions for water
reversion. In the second test program, three boats were equipped with catalysts and operated for
an extended period similar to the fresh water testing.
4.5.3.3.1 Safety, Durability, and Performance Testing
We contracted with SwRI to test catalysts on a Sterndrive engine before and after
operation on a boat in saltwater.65 The purpose of the testing was to determine if the catalyst
would be damaged by water reversion in the exhaust manifold. This testing was performed on a
19 foot runabout with a 4.3 L Sterndrive engine. On previous testing on this boat without a
catalyst, SwRI found that the only water collected in the exhaust manifold was due to
condensation. They were able to prevent this condensation by fitting the water jacket around the
exhaust system with a thermostat to keep the manifold walls from becoming too cool.
The 4.3 L engine was fitted with a pair of riser catalysts similar to the one illustrated in
Figure 4.5-1. These catalysts had a cell density of 300 cpsi and a combined volume of 1.4 L.
The catalysts were water-jacketed to maintain low surface temperatures and, to prevent any
possible water reversion, cones were inserted in the exhaust elbows. These cones were intended
to increase the difficulty for water to creep up the inner walls of the exhaust manifold. The
water jacketing system was fitted with a 82°C thermostat to keep the manifold wall temperatures
4-51
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Draft Regulatory Impact Analysis
above the dew point of the exhaust gas (~50°C) thereby preventing water condensation in the
exhaust manifold.
Prior to testing, the catalysts were aged using a rapid aging cycle designed to represent
50,000 miles of vehicle operation. SwRI estimated that this would likely be more severe than
would be seen over the useful life of an SD/I engine. The engine was then tested for emissions,
in a test cell, with and without the aged catalysts installed in the exhaust manifold risers. In
addition to adding the catalysts, the engine fueling was optimized using closed-loop electronic
emission control.
After the baseline emission tests, the catalysts were installed on a 19 foot runabout
equipped with a similar 4.3 L engine used in the emissions test cell. The boat was operated on
saltwater over a number of safety, durability, and performance tests that were developed by
industry for heat soak, water ingestion, and engine exhaust back-pressure. In addition, SwRI
operated the boat over tests that they designed to represent operation and use that would most
likely induce water reversion. After this boat testing, the catalyst was returned to the laboratory
for a repetition of the baseline emission tests.
Table 4.5-8 presents the baseline, aged catalyst, and post boat operation catalyst emission
test results. No significant deterioration of the catalysts were observed. Prior to boat testing, the
aged catalysts achieved a 75 percent reduction in HC+NOx and a 36 percent reduction in CO.
After the boat operation in saltwater, the catalysts achieved a 73 percent reduction in HC+NOx
and a 34 percent reduction in CO. As described in Chapter 3, if saltwater had reached the
catalyst, there would have been a large reduction in catalyst efficiency. No salt deposits were
observed on the catalysts when they were removed from the boat.
Table 4.5-8: Exhaust Emission Data on a 4.3 L SD/I Engine with Catalysts
Catalyst Scenario
open-loop, no catalyst
closed-loop, no catalyst
aged catalyst pre boat
aged catalyst post boat
HC
[g/kW-hr]
4.9
4.5
2.1
2.2
NOx
[g/kW-hr]
11.7
10.4
2.0
2.3
CO
[g/kW-hr]
111
101
70
73
Power
[kW]
153
153
154
150
BSFC
[g/kW-hr]
329
327
321
327
4.5.3.3.2 Extended Period In-Use Testing
We engaged in a test program with the California Resources Board, United States Coast
Guard, National Marine Manufacturers Association, the Texas Department of Parks and
Wildlife, and Southwest Research Institute to evaluate three additional engines with catalysts in
vessels operating on salt-water. Early in the program, two of the three manifolds experienced
corrosion in the salt-water environment resulting in water leaks and damage to the catalyst.
4-52
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Feasibility of Exhaust Emission Control
These manifolds were rebuilt with guidance from experts in the marine industry and additional
hours were accumulated on the boats. Although the accumulated hours are well below the 480
hours performed on fresh water, the completed operation showed no visible evidence of water
reversion or damage to the catalysts. Table 4.5-9 presents initial exhaust emission results for the
three engines, equipped with catalysts, included in this test program.
Table 4.5-9: Baseline Emission Data for Engines/Catalysts in Saltwater Test Program
Catalyst Scenario
Maxum, 4.3L V6, ceramic catalysts
Sea Ray, 5.7L V8, metal catalysts
Malibu, 5.7L V8, ceramic catalysts
HC
[g/kW-hr]
2.1
1.3
0.5
NOx
[g/kW-hr]
0.7
0.3
0.4
CO
[g/kW-hr]
136
114
107
Power
[kW]
150
191
194
BSFC
[g/kW-hr]
345
351
348
4.5.3.4 Production Engines
To date, one manufacturer is selling inboard Marine SI engines equipped with catalysts.
These engines are certified in California and are being sold nationwide. The engines are based
on 5.7L automotive blocks and use electronically controlled fuel injection, twin catalysts, and
onboard diagnostics. The manufacturer, Indmar, has also performed extended durability testing
in a saltwater environment. Test data from this engine is presented in Table 4.5-10, with and
without an applied deterioration factor.66 One advantage that Indmar has promoted with this
engine is very low CO at part throttle. Part throttle operation is associated with lower boat
speeds where the risk of CO poisoning is highest. The measured CO over the marine duty cycle
is primarily due to emissions at wide open throttle, where the engine goes to open loop rich
operation to protect the exhaust valves from overheating.
Table 4.5-10: Exhaust Emission Data on a 5.7L Production SD/I Engine with Catalysts
measured test results
with deterioration factor applied
HC
[g/kW-hr]
1.8
2.0
NOx
[g/kW-hr]
2.0
2.3
CO
[g/kW-hr]
46.6
51.8
Other marine engine manufacturers have indicated that they will produce catalyst-
equipped SD/I engines, certified to the California emission standards, by the end of this year.
4.5.3.5 CO Emissions Reductions at Low versus High Power
Under stoichiometric or lean conditions, catalysts are effective at oxidizing CO in the
exhaust. However, under very rich conditions, catalysts are not effective for reducing CO
4-53
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Draft Regulatory Impact Analysis
emissions. SD/I engines often run at high power modes for extended periods of time. At these
temperatures, engine marinizers must calibrate the engine to run rich as an engine protection
strategy. If the engine were calibrated for a stoichometric air-fuel ratio at high power, high
temperatures could lead to failures in exhaust valves and engine heads.
All of the data presented above on SD/I engines equipped with catalysts were based on
engines that used open-loop engine control at high power. As a result, the catalysts achieved
little reduction in HC and CO at full power (test mode 1). However, NOx reductions were
achieved at mode 1 because NOx is effectively reduced under rich conditions.
The catalysts were effective in reducing CO in modes 2 through 5 of the proposed test
procedure. In these lower power modes, the engines described above saw CO reductions on the
order of 80 percent. However, the weighted values over the proposed test cycle only show about
a 50 percent reduction in CO because of the high contribution of mode 1 to the total weighted
CO value. Studies have shown that there is a higher risk of operator exposure to CO at lower
boat speeds67 which would correspond to lower engine power modes. This suggests that CO
reductions at lower power modes may be more beneficial than CO reductions at full power.
To look at the effect of mode 1 on the cycle weighted CO levels, we performed an
analysis in which we recalculated the CO level for ten catalyst-equipped SD/I engines without
mode 1. To determine the weighted value without mode 1, the weighting factor for mode 1 was
set to zero percent and the weighting factors for modes 2 and 3 were each increased so that
weighting factors would sum to 100 percent. Figure 4.5-2 compares the CO emissions with and
without including mode 1 for these engines. Although mode 1 is only weighted as 6 percent of
the proposed test cycle, but makes up the majority of the cycle weighted CO value. Based on
this analysis, the weighed CO level would be 70-90 percent lower if mode 1 were not included in
the test procedure.
4-54
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Feasibility of Exhaust Emission Control
Figure 4.5-2: CO Emissions for SD/I Engines Equipped with Catalysts
with and without Including Mode 1 in the Weighted Results
140
120
100
DE4 Weighting
• Without Mode 1
10
4.6 Feasibility of Standard for Marine Generator Sets
Currently, SI marine generator sets are regulated as Small SI or Large SI engines,
depending on their size. Most SI marine generators are less than 25 hp and are therefore
classified as Small SI engines. Generator sets in marine applications are unique in that they use
liquid-cooled engines. Liquid cooling allows manufacturers to minimize the temperature of hot
surfaces on marine generators, thereby reducing the risk of fires on a boat. For marine
applications, liquid cooling is practical because of the nearly unlimited source of cooling water
around the boat.
Another safety issue that has become apparent in recent years is carbon monoxide
poisoning on boats. Studies have shown that exhaust emissions from engines on boats can lead
to user exposure of high levels of carbon monoxide.68 The marine industry, Coast Guard,
American Boat and Yacht Council, and other stakeholders have been meeting regularly over the
past several years in an attempt to mitigate the risk of CO poisoning in boating.69'70 Mitigation
strategies that have been discussed at these meetings include labeling, education, diverting the
exhaust flow with smoke stacks, CO detectors, low CO emission technologies, and emission
standards.
The vast majority of gasoline marine generators are produced by two engine
manufacturers. Recently, these two manufacturers have announced that they are converting their
marine generator product lines over to low CO engines.71'72 They have stated that this is to
reduce the risk of CO poisoning and that this action is a result of boat builder demand. Both
4-55
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Draft Regulatory Impact Analysis
manufacturers are using a combination of closed-loop electronic fuel injection and catalytic
control. To date, both of these manufacturers have certified some low CO engines and have
stated their intent to convert their full product lines in the near future. These manufacturers also
make use of the electronic controls to monitor catalyst function. Table 4.6-1 presents the 2005
model year certification levels for these engines.
Table 4.6-1: 2005 MY Certification Levels for Low CO Marine Generator Engines
Engine
Manufacturer
Kohler Power
Systems
Westerbeke
Power
[kW]
10.2
7.5
17.9
Emission Control System
throttle-body injection, O2 sensor, catalyst
throttle-body injection, O2 sensor, catalyst
throttle-body injection, O2 sensor, catalyst
HC+NOx
[g/kW-hr]
7.2
2.0
4.4
CO
[g/kW-hr]
5.2
0.01
0.0
In use testing has been performed on two marine generator engine equipped with
catalysts. These engines were installed on rental houseboats and operated for a boating season.
Testing was first performed with low hours of operation; 108 hours for the 14 kW engine and
159 hours for the 20 kW.73 The CO performance was reported to be "impressive with exhaust
stack CO emissions of approximately 200 ppm for a fully warmed generator." The emissions
measured around the boat were much lower due to dilution. According to the manufacturer, no
significant deterioration has been found in the emission performance of the catalysts. Note that
the manufacturer recommends changing the catalysts at 2000 hours and inspecting for CO at
1000 hours.
4.7 Test Procedures
We are proposing several technical amendments to the existing exhaust emission test
procedures for Small SI and OB/PWC engines. These amendments are part of a larger effort to
develop uniform test procedures across all of our programs. We are proposing to include SD/I
engines in these test procedures. In addition we are proposing not-to-exceed requirements for
Marine SI engines. These new procedures are discussed in this section.
4.7.1 SD/I Certification Test Procedure
We are proposing to use the same certification duty cycle and test procedures for all
Marine SI engines, including sterndrives and inboards. Table 4.5-6 presents the proposed
certification test duty cycle. This duty cycle is commonly referred to as the E4 duty cycle and
was developed using operational data on outboard and sterndrive marine gasoline engines.74 In
addition, the E4 duty cycle is recommended by the International Standards Organization for use
with all spark-ignition pleasurecraft less than 24 meters in length.75 Although some Marine SI
engines may be used for commercial activities, these engines would not likely be made or used
differently than those used for pleasure.
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Feasibility of Exhaust Emission Control
Table 4.7-1: SI Marine Certification Steady-State Test Duty Cycle
Mode
1
2
3
4
5
% of Maximum Test
Speed (MES)
100
80
60
40
idle
% of Maximum Torque
at MES
100
71.6
46.5
25.0
0
% of Maximum Power*
at MES
100
57.2
27.9
10.1
0
Weighting
Factor
0.06
0.14
0.15
0.25
0.40
*% power = (% speed) x (% torque).
4.7.2 SI Marine Not-To-Exceed Requirements
EPA is concerned that if a marine engine is designed for low emissions on average over a
low number of discrete test points, it may not necessarily operate with low emissions in-use.
This is due to a range of speed and load combinations that can occur on a vessel which do not
necessarily lie on the test duty cycle. For instance, the test modes on the E4 duty cycle lie on an
average propeller curve. However, a propulsion engine may never be fitted with an "average
propeller." In addition, a light planing hull boat may operate at much lower torques than a
heavily loaded boat.
It is our intent that an engine operate with low emissions under all in-use speed and load
combinations that can occur on a boat, rather than just the discrete test modes in the five-mode
duty cycle. To ensure this, we are proposing requirements that extend to typical in-use
operation. We are proposing not-to-exceed (NTE) requirements similar to those established for
marine diesel engines. Under this approach, manufacturers would design their engines to
comply with a not-to-exceed limit, tied to the standard, for HC+NOx and CO, within the NTE
zone. In the cases where the engine is included in averaging, banking, and trading of credits, the
NTE limits would be tied to the family emission limits. We would reserve the right to test an
engine in a lab or installed in a boat to confirm compliance to this requirement.
We believe there are significant advantages to taking this approach. The test procedure is
very flexible so it can represent the majority of in-use engine operation and ambient conditions.
Therefore, the NTE approach takes all of the benefits of a numerical standard and test procedure
and expands it to cover a broad range of conditions. Also, laboratory testing makes it harder to
perform in-use testing because either the engines would have to be removed from the vessel or
care would have to be taken that laboratory-type conditions can be achieved on the vessel. With
the NTE approach, in-use testing and compliance become much easier because emissions may be
sampled during normal vessel use. Because this approach is objective, it makes enforcement
easier and provides more certainty to the industry of what is expected in use versus over a fixed
laboratory test procedure.
Even with the NTE requirements, we believe it is still important to retain standards based
on the steady-state duty cycle. This is the standard that we expect the certified marine engines to
meet on average in use. The NTE testing is more focused on maximum emissions for segments
4-57
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Draft Regulatory Impact Analysis
of operation and should not require additional technology beyond what is used to meet the
proposed standards. We believe basing the emission standards on a distinct cycle and using the
NTE zone to ensure in-use control creates a comprehensive program. In addition, the steady-
state duty cycles give a basis for calculating credits for averaging, banking, and trading.
We believe that the same technology that can be used to meet the standards over the five-
mode certification duty cycle can be used to meet the NTE caps in the NTE zone. We therefore
do not expect the proposed NTE standards to cause marinizers to need additional technology.
We do not believe the NTE concept results in a large amount of additional testing, because these
engines should be designed to perform as well in use as they do over the steady-state five-mode
certification test.
4.7.2.1 Shape of the NTE Zone
The proposed NTE zone is intended to capture typical in-use operation for marine
vessels. We used two data sources to define this operation. The first data source was the
collection of data on marine engine operation that was used to develop the ISO E4 steady-state
duty cycle.76 Speed and torque data were collected on 33 outboards and three sterndrives. This
data showed that the marine engines generally operated along a propeller curve with some
variation due to differences in boat design and operation. A propeller curve defines the
relationship between engine speed and torque for a marine engine and is generally presented in
terms of torque as a function of engine speed in RPM raised to an exponent. The paper uses an
exponent of 1.5 as a general fit, but states that the propeller curves for Marine SI applications
range from exponents of 1.15 to 2.0.
The second source of data was a study of marine engine operation recently initiated by
the marine industry.77 In this study, sixteen boats were tested in the water at various engine
speeds. These boats included seven sterndrives, three inboards, four outboards, and two personal
watercraft. To identify the full range of loads at each engine speed, boats were operated both
fully loaded and lightly loaded. Boats were operated at steady speeds to identify torque at each
speed. In some cases, the operation was clearly unsafe or atypical. We did not include these
operating points in our analysis. An example of atypical operation would be with a boat so
highly loaded that it was operating in an unstable displacement mode with its bow sticking up
into the air.
Figure 4.7-1 presents test data from the two studies as well as the proposed NTE zone for
Marine SI engines. This zone includes operation above and below the theoretical propeller curve
used in the E4 duty cycle. Operation below 25 percent of rated speed is excluded because brake-
specific emissions at low loads becomes very high due to low power in the denominator. This
approach is consistent with the marine diesel NTE zone. The upper and lower borders of the
NTE zone are designed to capture all of the typical operation that was observed in the two
studies. The curve functions for these boarders are presented in Figure 4.7-1.
4-58
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Feasibility of Exhaust Emission Control
Figure 4.7-1: Proposed NTE Zone and Marine Engine Operation Data
1.2
0)
3
E
o
0)
N
0.4
0.2
100% Speed
Outboard
PWC
Inboard
• Sterndrive
x SAE901596
O E4 Setpoints
Prop Curve
Torque Curve
Draft NTE
Zone
Atypical Points
0%
20%
40% 60% 80%
Normalized Speed
1 00%
120%
When testing the engine within the NTE zone, only steady-state operation would be
considered. It is unlikely that transient operation is necessary under the NTE concept to ensure
that emissions reductions are achieved. We designed the proposed NTE zone to contain the
operation near an assumed propeller curve that the steady-state duty cycle represents. We
believe that the vast majority of the operation in the proposed NTE zone would be steady-state.
When bringing a boat to plane, marine engine operation would be transient and would likely be
above the proposed NTE zone. However we do not have enough information to quantify this.
Also we do not believe that the NTE zone should be extended to include areas an engine may see
under transient operation, but not under steady-state operation. For this reason, we do not
believe that adding transient operation to the NTE requirements is necessary at this time. We
would revise this opinion in the future if there were evidence that in-use emissions were
increased due to insufficient emission control under transient operation
4.7.2.2 Emissions Limits for the NTE Zone
We are proposing emission caps for the NTE zone which represent a multiplier times the
weighted test result used for certification. Although ideally the engine should meet the
certification level throughout the NTE zone, we understand that a cap of 1.0 times the standard is
4-59
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Draft Regulatory Impact Analysis
not reasonable because there is inevitably some variation in emissions over the range of engine
operation. This is consistent with the concept of a weighted modal emission test such as the E4
duty cycle.
In developing proposed emission caps in the NTE zone, we collected modal HC+NOx
and CO emission data on a large number of OB, PWC, and SD/I engines. Because limited modal
data is available in published literature,78'79'80 most of the modal data on outboards and personal
watercraft was provided confidentially by individual manufacturers. Data on SD/I engines with
catalysts was collected as part of the catalyst development efforts discussed earlier in this
chapter.81'82'83'84 Our analysis focuses only on engines using technology that could be used to
meet the proposed standards. The modal data is presented in Figures 4.7-2 through 4.7-9 in
terms of the modal emission rate divided by the weighted E4 average for that engine. Each color
bar represents a different engine. Because of the large volume of data and differences in engine
operation an emissions performance, data is presented separately for carbureted 4-stroke, fuel-
injected 4-stroke, and direct-injected 2-stroke OB/PWC, and for catalyst-equipped SD/I engines.
Figures 4.7-2 and 4.7-4 present normalized HC+NOx modal data for carbureted and EFI
4-stroke OB/PWC engines. Note that most of the data points are near or below the E4 weighted
average (represented by bars near or below 1.0). This is largely due to the exclusion of idle
operation from the NTE zone compared to the E4 duty cycle that is 40 percent weighted at idle.
As mentioned above, idle is excluded because brake-specific emissions become very large at low
power due to a low power figure in the denominator (g/kW-hr). Especially for the carbureted
engines, higher normalized HC+NOx emissions are observed at the low power end of the NTE
zone (40 percent speed, 25 percent torque). As shown in Figures 4.7-3 and 4.7-5, a similar trend
is observed with normalized CO emissions from these engines.
4-60
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Feasibility of Exhaust Emission Control
Figure 4.7-2: Normalized Modal HC+NOx for Carbureted 4-Stroke OB/PWC
40%, 25% 60%? 47% 80%3/2% 100%4100%
Normalized Speed, Torque [% of rated]
Figure 4.7-3: Normalized Modal CO for Carbureted 4-Stroke OB/PWC
ra
0.0
40%, 25% 60%2 47% 80%372% 100%,4100%
Normalized Speed, Torque [% of rated]
4-61
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Draft Regulatory Impact Analysis
Figure 4.7-4: Normalized Modal HC+NOx for EFI 4-Stroke OB/PWC
LU
"re
-a
o
X
O
O
I
•o
0)
_N
"re
40%1 25% 60%2 47% 80%372%
Normalized Speed, Torque [% of rated]
100% 4100%
Figure 4.7-5: Normalized Modal CO for EFI 4-Stroke OB/PWC
0.0
40%, 25% 60°/2, 47% 80%372%
Normalized Speed, Torque [% of rated]
ioo%4ioo%
4-62
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Feasibility of Exhaust Emission Control
Figures 4.7-6 through 4.7-9 present normalized HC+NOx and CO modal data for direct-
injected 2-stroke OB/PWC engines. Based on the data collected, there appear to be two distinct
types of direct-injection 2-stroke engines. One manufacturer uses a higher pressure fuel system
with a unique combustion chamber design for low emissions. Because the modal variation in
emission results are significantly different for the two engine designs, we designate them
headings of Type 1 and Type 2 engines and look at them separately for the purposes of this
analysis. As shown in Figure 4.7-6 and 4.7-7, Type 1 engines tend to have relatively high
HC+NOx at low power, then fairly low emissions over the rest of the modes. For CO, these
engines show much less variability between modes. For Type 2 engines, HC+NOx is below the
E4 average in the mid-speed range as shown in Figure 4.7-8. However, there is a wide degree of
variation in how these engines behave at low and high speed. Most of these engines seem to
have high normalized HC+NOx emissions either at low or at high speed. Figure 4.7-9 presents
CO values for Type 1 engines. These engines tend to have high CO at full power with
decreasing CO at lower power modes.
Figure 4.7-6: Normalized Modal HC+NOx for Type 1 DI 2-Stroke OB/PWC
40%, 25% 60%247% 80% ,372%
Normalized Speed, Torque [% of rated]
100% ,4100%
4-63
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Draft Regulatory Impact Analysis
Figure 4.7-7: Normalized Modal CO for Type 1 DI 2-Stroke OB/PWC
40%, 25% 60%247% 80%,^2% 100%, 400%
Normalized Speed, Torque [% of rated]
Figure 4.7-8: Normalized Modal HC+NOx for Type 2 DI 2-Stroke OB/PWC
0.0
40%, 25% 60%247% 80% ,372% 100% ,4100%
Normalized Speed, Torque [% of rated]
4-64
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Feasibility of Exhaust Emission Control
Figure 4.7-9: Normalized Modal CO for Type 2 DI 2-Stroke OB/PWC
40%, 25% 60%247% 80%,^2% 100%, 400%
Normalized Speed, Torque [% of rated]
Figures 4.7-10 and 4.7-11 present normalized HC+NOx and CO modal data for SD/I
engines equipped with catalysts. All of these engines demonstrated HC+NOx emissions below
the E4 average in the mid-speed range. However, some of these engines show somewhat higher
normalized HC+NOx emissions at either the low-power or full power mode. These differences
are likely a function of catalyst design and location as well as air/fuel calibration. At wide open
throttle, all of these engines were calibrated to run rich as an engine protection strategy, so
emission reductions at this mode are due to NOx reductions in the catalyst. Because these
engines are designed to run rich at full power, high CO emissions were observed at this mode.
For the rest of the power range, CO emissions were generally below the E4 average for these
engines. As part of the catalyst development work for SD/I engines, one engine was tested over
26 modes, most of which are contained in the proposed NTE zone.85 This engine was tested in
its baseline configuration (open-loop fuel injection) as well as with three catalyst configurations.
The three catalyst configurations included one close-coupled to the engine (in the riser), one a
little farther downstream (in the exhaust elbow), and a larger catalyst external to the existing
exhaust manifold. This data provided insight into how exhaust emissions throughout the
proposed NTE zone for Marine SI engines compare to the modal test data on the theoretical
propeller curve. This data is presented in Appendix 4A.
4-65
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Draft Regulatory Impact Analysis
Figure 4.7-10: Normalized Modal HC+NOx for SD/I with
1O
1 A
LLJ
"J5 1 9
•8 i-<
O
u 1 n
1 — ' 1 .U
X
O
~2. n ft
+ U.o
O
1 OR
•o U.o
0)
N
1 0?
££ U.Z
On
Catalysts
i—
- n
Hh
n . I'
rl 11
n
n 1 r L~
HL II H
i
.U i i ii
40%, 25% 50%, 25% 60%,347% 70%, ,£9% 80%,572% 90%,
Normalized Speed, Torque [% of rated]
i
1
•
6^5% 100% ,71 00%
Figure 4.7-11: Normalized Modal CO for SD/I with Catalysts
3C
.0
3n
a 25
ra
•o
o
O
O
_ -I C
w 1 .O
"5
o
Oc
.0
On
n
1
1
-, _ •~T| IT-rn B-i
1
-
-
-
40%, 25% 50% 235% 60%347% 70% ,459% 80% 572% 90% ,635% 100% ,71 00%
Normalized Speed, Torque [% of rated]
4-66
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Feasibility of Exhaust Emission Control
Based on the above data, we believe that a single NTE limit is not appropriate for the
entire NTE zone. For this reason, we are proposing to divide the NTE zone into four subzones.
These subzones are numbered to correspond with the E4 mode that they contain. For instance,
subzone 1 includes full-power operation which is mode 1 in the E4 duty cycle. Subzone one is
all operation at or above 90 percent maximum test speed and/or 100 percent torque at maximum
test speed. Mode 2 is (operation below subzone 1) at or above 70 percent maximum test speed
and/or 80 percent torque at maximum test speed. Subzone 4 includes operation in the proposed
NTE zone at or below 50 percent speed. Subzone 3 includes the remaining section of the
proposed NTE zone. Figure 4.7-12 presents the proposed NTE zone and subzones.
Figure 4.7-12: Proposed NTE Zone and Subzones
120%
100%
80%
U"
o
o> 60%
N
re
E
100% Speed
90% Speed
70% Speed
SpeedA1.5-0.08
40%
20%
25.3% Torque
SpeedA1.5 (theoretical propeller curve)
0%
20%
40% 60% 80%
Normalized Speed
100%
120%
The data presented above suggests that separate NTE limits may be necessary for
HC+NOx and for CO. Also this data suggests that different NTE limits by be appropriate for
different engine types (especially catalyzed SD/I versus OB/PWC). We are proposing separate
NTE limits for SD/I and OB/PWC. These limits are presented in Table 4.7-2. In addition, due
to the wide variability of modal emission rates for the two types of direct-injected two-stroke
engines, we are proposing two alternative sets of NTE limits than manufacturers would have the
option of choosing for their OB/PWC engines. These alternative limits are based on the data
presented above and give more room in some subzones while imposing tighter caps in other
4-67
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Draft Regulatory Impact Analysis
subzones to give a net stringency roughly equivalent to the primary option. To offset these
relaxed standards in subzones 1 and 4, we are proposing more stringent limits in subzones 2 and
3 for this alternative approach.
Table 4.7-2: Proposed NTE Limits by Subzone
Application
SD/I
OB/PWC
(primary)
OB/PWC
(alternative 1)
OB/PWC
(alternative 2)
Pollutant
HC+NOx
CO
HC+NOx
CO
HC+NOx
CO
HC+NOx
CO
Subzone 4
1.5
1.0
1.6
1.5
2.0
1.0
3.0
2.0
Subzone 3
1.0
1.0
1.2
1.5
0.8
1.0
1.0
1.0
Subzone 2
1.0
1.0
1.2
1.5
0.8
1.5
1.0
1.0
Subzone 1
1.5
3.5
1.2
1.5
2.0
3.0
1.0
1.5
We used the modal data presented above and the data on additional operation points
presented in Appendix 4A to develop these NTE limits. The proposed limits represent the levels
that can be met by the majority of the marine engines tested. In the case of engines that have
modal emissions that are somewhat higher than the proposed NTE limits, we believe that these
engines can be calibrated to meet these proposed limits. In addition, the limits are based on the
Family Emission Limits chosen by manufacturers at certification. Therefore, manufacturers
would have the option of increasing their FELs, in some cases, to bring otherwise problem
engines into compliance with the proposed NTE limits.
4.7.2.3 Ambient Conditions
Ambient air conditions, including temperature and humidity, may have a significant
effect on emissions from marine engines in-use. To ensure real world emissions control, the
NTE zone testing should include a wide range of ambient air conditions representative of real
world conditions. Because these engines are used in similar environments as marine diesel
engines, we are proposing to apply the same ambient ranges to the Marine SI NTE requirements
as already exist for marine diesel engine NTE requirements.
We believe that the appropriate ranges should be 13-30°C (55-86°F) for air temperature
and 7.1-10.7 grams water per kilogram dry air (50-75 grains/pound of dry air) for air humidity.
The air temperature ranges are based on temperatures seen during ozone exceedences, except
that the upper end of the temperature range has been adjusted to account for the cooling effect of
a body of water on the air above it.86 We are also aware, however, that marine engines
sometimes draw their intake air from an engine compartment or engine room such that intake air
temperatures are substantially higher than ambient air temperatures. In this case, we would
retain 35°C as the end of the NTE temperature range for engines that do not draw their intake air
4-68
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Feasibility of Exhaust Emission Control
directly from the outdoor ambient.
For NTE testing in which the air temperature or humidity is outside the proposed range,
we propose that the emissions must be corrected back to the specified air temperature or
humidity range. These corrections would be consistent with the equations in 40 CFR Part 91,
Subpart E except that these equations correct to 25°C and 10.7 grams per kilogram of dry air
while the NTE corrections would be to the nearest outside edge of the specified ranges. For
instance, if the outdoor air temperature were higher than 30°C for an engine that drew fresh
outdoor air into the intake, a temperature correction factor could be applied to the emissions
results to determine what emissions would be at 30°C.
Ambient water temperature also may affect emissions due to it's impact on engine
cooling. For this reason, we are proposing that the NTE testing include a range of ambient water
temperatures from 5 to 27°C (41 to 80°F). The proposed water temperature range is based on
temperatures that marine engines experience in the U.S. in-use. At this time, we are not aware of
an established correction for ambient water temperature, therefore the NTE zone testing would
have to be withing the specified ambient water temperature range.
4.8 Impacts on Safety, Noise, and Energy
Section 213 of the Clean Air Act directs us to consider the potential impacts on safety,
noise, and energy when establishing the feasibility of emission standards for nonroad engines.
Furthermore, section 205 of Public Law 109-54 requires us to assess potential safety issues,
including the risk of fire and burn to consumers in use, associated with the proposed emission
standards for nonroad spark-ignition engines under 50 horsepower. As further detailed in the
following sections, we expect that the proposed exhaust emission standards will either have no
adverse affect on safety, noise, and energy or will improve certain aspects of these important
characteristics.
4.8.1 Safety
We conducted a comprehensive, multi-year safety study of nonroad SI engines that
focused on the following areas where we are proposing new exhaust standards.87 These areas
are:
New catalyst-based HC+NOx exhaust emission standards for Class I and II
nonhandheld (NHH) engines; and
New HC+NOx exhaust emission standards for outboard and personal watercraft
(OB/PWC) engines and vessels, and a new CO exhaust emission standard for
NHH engines used in marine auxiliary applications.
Each of these four areas is discussed in greater detail in the next sections.
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Draft Regulatory Impact Analysis
4.8.1.1 Exhaust Emission Standards for Small Spark-Ignition Engines
The technology approaches that we assessed for achieving the proposed Small SI engine
standards included exhaust catalyst aftertreatment and improvements to engine and fuel system
designs. In addition to our own testing and development effort, we also met with engine and
equipment manufacturers to better understand their designs and technology and to determine the
state of technological progress beyond EPA's Phase 2 standards.
The scope of our safety study included Class I and Class II engine systems that are used
in residential walk-behind and ride-on lawn mower applications, respectively. Residential lawn
mower equipment was chosen for the following reasons.
Lawn mowers and the closely-related category of lawn tractors overwhelmingly
represent the largest categories of equipment using Class I and Class II engines. We
estimate that over 47 million walk-behind mowers and ride-on lawn and turf
equipment are in-use in the US today.
These equipment types represent the majority of sales for Small SI engines.
- Consumer Product Safety Commission (CPSC) data indicates that more thermal burn
injuries associated with lawn mowers occur than with other NHH equipment; lawn
mowers therefore represent the largest thermal burn risk for these classes of engines.
- General findings regarding advanced emission control technologies for residential
lawn and garden equipment carry over to commercial lawn and turf care equipment as
well as to other NHH equipment using Class I and Class II engines. Lawn mower
design and use characteristics pose unique safety implications not encountered by
other NHH equipment using these engines (i.e. a mower deck collects debris during
operation whereas a pressure washer collects no debris). Thus, other NHH equipment
may employ similar advanced emission control technologies for meeting the
proposed standards without a corresponding concern regarding the safety issues
analyzed in this study.
We conducted the technical study of the incremental risk on several fronts. First,
working with the CPSC, we evaluated their reports and databases and other outside sources to
identify those in-use situations which create fire and burn risk for consumers. The outside
sources included meetings, workshops, and discussions with engine and equipment
manufacturers. The following scenarios were identified for evaluation:
- Thermal burns due to inadvertent contact with hot surface on engine or equipment;
Fires from grass and leaf debris on the engine or equipment;
Fires due to fuel leaks on hot surfaces;
Fires related to spilled fuel or refueling vapor;
Equipment or structure fire when equipment is left unattended after being used;
Engine malfunction resulting in an ignitable mixture of unburned fuel and air in the
muffler (engine misfire); and
- Fire due to operation with richer than designed air-fuel ratio in the engine or catalyst.
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Feasibility of Exhaust Emission Control
These scenarios cover a comprehensive variety of in-use conditions or circumstances
which potentially could lead to an increase in burns or fires. They may occur presently or not at
all, but were included in our study because of the potential impact on safety if they were to
occur. The focus of the analysis was, therefore, on the incremental impact on the likelihood and
severity of the adverse condition in addition to the potential causes as it related to the use of
more advanced emissions control technology.
Second, we conducted extensive laboratory and field testing of both current technology
(Phase 2) and prototype catalyst-equipped advanced-technology engines and equipment (Phase
3) to assess the emission control performance and thermal characteristics of the engines and
equipment. This testing included a comparison of exhaust system, engine, and equipment
surface temperatures using thermal imaging equipment.
Third, we contracted with Southwest Research Institute (SwRI) to conduct design and
process Failure Mode and Effects Analyses (FMEA).88 The SwRI FMEA focused on comparing
current Phase 2 and Phase 3 compliant engines and equipment to evaluate incremental changes
in risk probability as a way of evaluating the incremental risk of upgrading Phase 2 engines to
meet Phase 3 emission standards. This is an engineering analysis tool to help engineers and
other professional staff on the FMEA team to identify and manage risk. In a FMEA, potential
failure modes, causes of failure, and failure effects are identified and a resulting risk probability
is calculated from these results. This risk probability is used by the FMEA team to rank
problems for potential action to reduce or eliminate the causal factors. Identifying these causal
factors is important because they are the elements that a manufacturer can consider reducing the
adverse effects that might result from a particular failure mode.
Our technical work and subsequent analysis of all of the data and information strongly
indicate that effective catalyst-based standards can be implemented without an incremental
increase in the risk of fire or burn to the consumer either during or after using the equipment.
Similarly, we did not find any increase in the risk of fire during storage near typical combustible
materials. In many cases, the designs used for catalyst-based technology can lead to an
incremental decrease in such risk.
More specifically, our work included taking temperature measurements and infrared
thermal images of both OEM mufflers and prototype catalyst/mufflers on six Class 1 engines and
three Class 2 engines as part of the safety study. We integrated the emission reduction catalyst
into the muffler. In doing so, we generally designed heat management features into the
catalyst/muffler and cooling system. These heat management design elements, all of which were
not used on every prototype, included: 1) positioning the catalyst within the cooling air flow of
the engine fan or redirecting some cooling air over the catalyst area with a steel shroud; 2)
redirecting exhaust flow through multiple chambers or baffles within the catalyst/muffler; 3)
larger catalyst/muffler volumes than the original equipment muffler; and 4) minimizing CO
oxidation at moderate to high load conditions to maintain exhaust system surface temperatures
comparable to those of the OEM systems. The measurements and images were taken during
various engine operating conditions and as the engines cooled down after being shut off. This
latter event, termed "hot soak," is an important consideration since it is often when the operator
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Draft Regulatory Impact Analysis
is in close proximity to the engine either performing maintenance or refueling the equipment.
Figures 4.8-1 and 4.8-2 are an example of the measurements and images taken to
compare Class 1 engine original equipment (OEM) mufflers to the same engines equipped with
prototype catalyst/mufflers. The first figure depicts surface temperatures from engine number
244 while operated on a laboratory dynamometer over three modes of EPA's A-cycle steady-
state test cycle. The second figure shows surface temperatures for the same engine at different
times during hot soak. The prototype catalyst/muffler system shown in these figures uses one of
the most effective heat management designs in the safety study. As shown, the catalyst system
in this example has much lower surface temperatures during both engine operation and hot soak.
Similar information was collected in the laboratory for Class 2 engines used in lawn
tractors. However, those tests were conducted on the "raw" engines without the chassis, which
is an integral part of the overall engine cooling system for most residential Class 2 applications.
Because of this, we believe it is more appropriate to compare the thermal measurements from
field testing of the integrated unit.
The test results for engine 251 are fairly typical of the Class 2 lawn tractor test results.
During engine operation, the OEM muffler configuration had exposed surface temperatures of
approximately 200 °C as viewed from both sides of the tractor when cutting moderate to heavy
grass and peak temperatures as high as 300 to 365 °C. The lawn tractor equipped with engine
253, which is from the same engine family as number 251, was fitted with a prototype
catalyst/muffler exhibited exposed surface temperatures of approximately 115 to 130 °C and
peaks of 160 to 190 °C. The lower temperatures for the prototype catalyst system is in part due
to the more effective cooling of the catalyst/mufflers due to the re-routing of cooling air through
the chassis and other heat management design elements.
The hot soak results for the above engines and two other related Class 2 lawn mowers are
shown in Figure 4.8-3. The two-minute nominal refueling point after engine shut-down
following 30 minutes of grass-cutting operation is shown for reference. In these tests, both of
the engines with prototype catalyst/mufflers had lower peak surface temperatures than the OEM
muffler configurations.
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Feasibility of Exhaust Emission Control
Figure 4.8-1: Surface Temperature Infrared Thermal Images of Exhaust System
Components for Class 1 Engine 244 with a Catalyst/Muffler (left) and an OEM Muffler
(right) at Various Operating Modes.
YtHtaa. f eccindary air
lQG%Loajd-Wids GtJen Throttle
rffino
aximum surf ace temperature: 230 °C
50% Load -Mode 3
*:•
log
no
Maximum surf ace temper^ure: 1D2 °C
Load-Mode 5
ace temperature: 161
OEM Muffler
100%Load-Widfi Gten Thnoflls
rSttD
aximum surf ace temperature: 551 °C
Load -Mode 3
an
no
Maximum surf ace temperaure: 421 °C
Load -Mode 5
ace temperature: 363 1C
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Draft Regulatory Impact Analysis
Figure 4.8-2: Hot Soak Surface Temperature Infrared Thermal Images of Exhaust System
Components for Class 1 Engine 244 After Sustained Wide Open Throttle and 100 Percent
Load.
Modified
MaadmunL funace temperature: 234 * C
100
HO
Maximum, surface temperature: 240 *C
su
; temperature: 215 * C
OEMTifufflo:
temperature: 418 * C
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Feasibility of Exhaust Emission Control
Figure 4.8-3: Hot Soak Peak Surface Temperatures Infrared Thermal Images for Class 2
Lawn Tractors Following After Approximately 30-Minutes of Grass Cutting.
o
I
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Draft Regulatory Impact Analysis
safety standards and the good in-use experience with advanced-technology engines in the current
vessel fleet, we believe new emission standards would not create an incremental increase in the
risk of fire or burn to the consumer.
4.8.2 Noise
As automotive technology demonstrates, achieving low emissions from spark-ignition
engines can correspond with greatly reduced noise levels. Direct-injection two-stroke and four-
stroke OB/PWC have been reported to be much quieter than traditional carbureted two-stroke
engines. Catalysts in the exhaust act as mufflers which can reduce noise. Additionally, adding a
properly designed catalyst to the existing muffler found on all Small SI engines can offer the
opportunity to incrementally reduce noise.
4.8.3 Energy
Adopting new technologies for controlling fuel metering and air-fuel mixing, particularly
the conversion of some carbureted engines to advanced fuel injection technologies, will lead to
improvements in fuel consumption. This is especially true for OB/PWC engines where we
expect the proposed standards to result in the replacement of old-technology two stroke engines
with more fuel efficient technologies such as two-stroke direct injection or four-stroke engines.
Carbureted crankcase-scavenged two-stroke engines are inefficient in that 25 percent or more of
the fuel entering the engine may leave the engine unburned. We estimate a fuel savings of about
61 million gallons of gasoline from marine engines in 2030, when most boats would be using
engines complying with the proposed standard.
The conversion of some carbureted Small SI engines to fuel injection technologies is also
expected to improve fuel economy. We estimate approximately 18 percent of the Class II
engines will be converted to fuel injection and that this will result in a fuel savings of about 10
percent for each converted engine. This translates to a fuel savings of about 56 million gallons
of gasoline in 2030 when all of the Class II engines used in the U.S. will comply with the
proposed Phase 3 standards. By contrast, the use of catalyst-based control systems on Small SI
engines is not expected to change their fuel consumption characteristics. These estimates are
discussed in more detail in Chapter 6.
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Feasibility of Exhaust Emission Control
APPENDIX 4A: Normalized Modal Emissions for a 7.4 L MPI SD/I
Figure 4A-1: HC+NOx Ratios for 7.4L MPI Engine, Baseline
140%
120%
1.1
0.3
n. 08
0.4 o
05 n 7 o
°x4 0.3 0^5
0.4 ° 05 13
& 0.5 04 ^ <>
0.6 a «
« 0.4 0.4
°,8 0.6 *
15
NA
% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%
Normalized Speed
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Draft Regulatory Impact Analysis
Figure 4A-3: HC+NOx Ratios for 7.4L MPI Engine, Riser Catalysts
140%
120%
CD 100%
3
Z
I— 80%
T3
CD
N
To wv°
E
0
Z 40%
20%
0%
0
07
0.7
0
0.6
0.8
° 0.9 °,8
°<° 0.7 O.Q °o9
°,5 07 07
°«9 HA ° °^ 16°
o 0.4 -| Q o
16 a '
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Feasibility of Exhaust Emission Control
Figure 4A-5: HC+NOx Ratios for 7.4L MPI Engine, Elbow Catalysts
140%
120%
0 100%
I— 80%
T3
0
N
CO 60/0
0
~Z. 40%
20%
0%
0
06
* 0.5
0
0.6
0- °^6 ^ n^
n rii U 5
Tjd 0.4 °
°xfi 0.5 °63
°<>5 n ^ 0.2 05
H 0.5 ° ^
17 05 *
& 0.4 0.9
^ °A3
167
NA
% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%
Normalized Speed
Figure 4A-6: CO Ratios for 7.4L MPI Engine, Elbow Catalysts
140%
120%
0 100%
I— 80%
N
0
~Z. 40%
20%
0%
0
1 6
'" 1.7
o
1.8
0,5
03 °-7 * 06
' ^ 064 d
0X4 0.3 9;1
°^ V 04 °^
0,4 0 o
0 0 4 0.5
0,4 <> °
** 01
°68
NA
% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%
Normalized Speed
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Draft Regulatory Impact Analysis
Figure 4A-7: HC+NOx Ratios for 7.4L MPI Engine, External Catalysts
140%
120%
CD 100%
3
Z
I— 80%
T3
CD
N
To wv°
E
0
Z 40%
20%
0%
0
0.4
0.3
0.3
°o3 H
0.3
0.3 o
n ? ° n t
Y;0 n o U-J
°a3 0^3 o
°o6 0.3 0,2
°/ 02 a4 °,3 &
1.4 Q1 d °
6 °<56 °<>6
V 0.0
°,5
NA
% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%
Normalized Speed
Figure 4A-8: CO Ratios for 7.4L MPI Engine, External Catalysts
140%
120%
0 100%
3
£•
I— 80%
*
N
ro so0/0
0
Z 40%
20%
0%
0
0.3
0.3
0.5
0.4 H
0.2 °^4
03° n =;
o n 1 UXD
° °a1 0,4 ^
°o8 0.3 0X1
°,4 04 as °.2 °^6
0,9 Q, d °
^ °<57 °<>7
V 0.0
°,1
NA
% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%
Normalized Speed
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Feasibility of Exhaust Emission Control
Chapter 4 References
1. Internal Combustion Engine Fundamentals, Heywood, J., McGraw-Hill, Inc., New York, 1988, pp.829-836,
Docket Identification EPA-HQ-OAR-2004-0008-0203.
2. Internal Combustion Engine Fundamentals, Heywood, J., McGraw-Hill, Inc., New York, 1988, pp.827-829,
Docket Identification EPA-HQ-OAR-2004-0008-0203.
3. Conversation between Tim Fileman at Flagship Marine and Mike Samulski at U.S. EPA, February 10, 1999.
4. "Benefits and Cost of Potential Tier 2 Emission Reduction Technologies," Energy and Environmental Analysis,
Final Report, November 1997, Docket Identification EPA-HQ-OAR-2004-0008-0198.
5. "Study on Air Assist Fuel Injector Atomization and Effects on Exhaust Emission Reduction," Saikalis, G., Byers,
R., Nogi., T.,SAE Paper 930323, 1993, Docket Identification EPA-HQ-OAR-2004-0008-0217.
6. "Three-Way Catalyst Technology for Off-Road Equipment Powered by Gasoline and LPG Engines," Southwest
Research Institute, prepared for CARB, CEP A, and SCAQMD, (SwRI 8778), April 1999, Docket Identification
EPA-HQ-OAR-2004-0008-0224.
7. Internal Combustion Engine Fundamentals, Heywood, J., McGraw-Hill, Inc., New York, 1988, pp. 836-839,
Docket Identification EPA-HQ-OAR-2004-0008-0203.
8. "Improving the NOx/Fuel Economy Trade-Off for Gasoline Engines with the CCVS Combustion System,"
Stokes, J., Lake, T., Christie, M., Denbratt, I., SAE Paper 940482, 1994, Docket Identification EPA-HQ-OAR-2004-
0008-0498.
9. Wu, H., Yang, S., Wang, A., Kao, H., "Emission Control Technologies for 50 and 125 cc Motorcycles in
Taiwan," SAE Paper 980938, 1998, Docket Identification EPA-HQ-OAR-2004-0008-0502.
10. Borland, M., Zhao, F., "Application of Secondary Air Injection for Simultaneously Reducing Converter-In
Emissions and Improving Catalyst Light-Off Performance," SAE Paper 2002-01-2803, 2001, Docket Identification
EPA-HQ-OAR-2004-0008-0497.
11. Koehlen, C., Holder, E., Guido, V., "Investigation of Post Oxidation and Its Dependency on Engine Combustion
and Exhaust Manifold Design," SAE Paper 2002-01-0744, 2002.
12. "Benefits and Cost of Potential Tier 2 Emission Reduction Technologies," Energy and Environmental Analysis,
Final Report, November 1997, Docket Identification EPA-HQ-OAR-2004-0008-0198.
13. "Reduction of Exhaust Gas Emissions by Using Pd-based Three-way Catalysts," Lindner, D., Lox, E.S.,
Kreuzer, T., Ostgathe, K., van Yperen, R., SAE Paper 960802, 1996, Docket Identification EPA-HQ-OAR-2004-
0008-0500.
14. "Overview of Recent Emission Control Technology Developments," Manufacturers of Emission Controls
Association, November 18, 1997, Docket Identification EPA-HQ-OAR-2004-0008-0206.
15. "Application of Accelerated Rapid Aging Test (RAT) Schedules with Poisons: The Effects of Oil Derived
Poisons, Thermal Degradation and Catalyst Volume on FTP Emissions," Ball, D., Mohammed, A., Schmidt, W.,
SAE Paper 972846, 1997, Docket Identification EPA-HQ-OAR-2004-0008-0501.
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Draft Regulatory Impact Analysis
16. "Update Heavy-Duty Engine Emission Conversion Factors for MOBILE6; Analysis of Fuel Economy, Non-
Engine Fuel Economy Improvements, and Fuel Densities," prepared by Arcadis for U.S. EPA, EPA420-R-006,
January 2002, Docket Identification EPA-HQ-OAR-2004-0008-0251.
17. "Overview of Recent Emission Control Technology Developments," Manufacturers of Emission Controls
Association, November 18, 1997, Docket Identification EPA-HQ-OAR-2004-0008-0206.
18. "Catalytic Converter Applications for Two Stroke, Spark-Ignited Marine Engines," Fujimoto, H., Isogawa, A.,
Matsumoto, N., SAE Paper 951814, 1995, Docket Identification EPA-HQ-OAR-2004-0008-0220.
19. "Catalytic Converter Applications for Two Stroke, Spark-Ignited Marine Engines," Fujimoto, H., Isogawa, A.,
Matsumoto, N., SAE Paper 941786, 1994, Docket Identification EPA-HQ-OAR-2004-0008-0218.
20. "Public Meeting to Consider a Status Report on Catalyst Testing of Spark-Ignition Inboard/Sterndrive
Pleasurecraft: Staff Report," State of California; Air Resources Board, October 28, 2004, Docket Identification EPA-
HQ-OAR-2004-0008-0236.
21. "Regulatory Impact Analysis—Control of Air Pollution from New Motor Vehicles: Tier 2 Motor Vehicle
Emissions Standards and Gasoline Sulfur Control Requirements," U.S. EPA, December 1999, EPA420-R-99-023,
http://www.epa.gov/otaq/regs/ld-hwy/tier-2/frm/ria/r99023.pdf
22. "Demonstration of Tier 2 Emission Levels for Heavy Light-Duty Trucks," J. McDonald and L. Jones, SAE
2000-01-1957, Docket Identification EPA-HQ-OAR-2004-0008-0496.
23. "SULEV and 'Off-Cycle' Emissions Benefits of a Vacuum-Insulated Catalytic Converter," Burch, S.D., and J.P.
Biel, SAE 1999-01-0461, Docket Identification EPA-HQ-OAR-2004-0008-0495.
24. "Development of an Alternator-Powered Electrically-Heated Catalyst System," Laing, P.M., SAE 941042,
Docket Identification EPA-HQ-OAR-2004-0008-0494.
25. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower", U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
26. "Nonroad SI Manufacturer Discussion," Slide 26-700cc Class II/Phase 2 Horizontal V-Twin. U.S.
Environmental Protection Agency, November 22, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0087.
27. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower", U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
28. "Test Results for Small Spark-Ignition Engine Number 258," Memorandum and Excel spreadsheet from Richard
Wilcox, Office of Transportation and Air Quality, U.S. Environmental Protection Agency, January 23, 2007, Docket
IdentificationEPA-HQ-OAR-2004-0008-0530.
29. Letter from David Raney, American Honda Motor Co., Inc., to Margo T. Oge, U. S. Environmental Protection
Agency, September 1, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0304.
30. Letter from Kent B. Herrick, Tecumseh Products Company, to Margo T. Oge, U. S. Environmental Protection
Agency, September 7, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0306.
31. Letter from Jeffrey Cl Shetler, Kawasaki Motors Corp, U.S.A., to Margo T. Oge, U. S. Environmental
Protection Agency, September 7, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0305.
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Feasibility of Exhaust Emission Control
32. Letter from James P. Doyle, Kohler Co., to Margo T. Oge, U. S. Environmental Protection Agency, September
7, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0303.
33. "Reducing Emissions From Gasoline Platforms at Less Then 20 kW," Slide 9, B. Walker and A. Gopalkrishna,
Delphi Automotive, Asian Vehicle Emission Control Conference, Jaipur, Japan, September 22, 2006. EPA-HQ-
OAR-2004-0008-0535.
34. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower", Appendix C - FMEA of Small SI Equipment and Engines, U.S. Environmental Protection Agency,
EPA420-R-06-006, March 2006, Docket Identification EPA-HQ-OAR-2004-0008-0329.
35. Letter from David Raney, American Honda Motor Co., Inc., to Margo T. Oge, U. S. Environmental Protection
Agency, September 1, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0304.
36. Letter from Kent B. Herrick, Tecumseh Products Company, to Margo T. Oge, U. S. Environmental Protection
Agency, September 7, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0306.
37. Letter from Jeffrey Cl Shetler, Kawasaki Motors Corp, U.S.A., to Margo T. Oge, U. S. Environmental
Protection Agency, September 7, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0305.
38. Letter from James P. Doyle, Kohler Co., to Margo T. Oge, U. S. Environmental Protection Agency, September
7, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0303.
39. "Reducing Emissions From Gasoline Platforms at Less Then 20 kW," Slide 9, B. Walker and A. Gopalkrishna,
Delphi Automotive, Asian Vehicle Emission Control Conference, Jaipur, Japan, September 22, 2006. EPA-HQ-
OAR-2004-0008-0535.
40. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower", Appendix C - FMEA of Small SI Equipment and Engines, U.S. Environmental Protection Agency,
EPA420-R-06-006, March 2006, Docket Identification EPA-HQ-OAR-2004-0008-0329.
41. "Nonroad SI Manufacturer Discussion," Slide 26-700cc Class II/Phase 2 Horizontal V-Twin. U.S.
Environmental Protection Agency, November 22, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0087.
42. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
43. "Research on the New Control Method Using Crankshaft Rotational Changes for Electronically Controlled FI
System of Small Motorcycle Single Cylinder Engine," Toichiro Hikichi, Tetsuya Kaneko, and Toshimitsu Nakajima,
Honda R&D Co., Ldt, SAE Paper 2006-32-0108, Small Engine Technology Conference and Exhibition, San
Antonio, Texas, November 13-16, 2006, Docket Identification EPA-HQ-OAR-2004-0008.
44. "Fuel Injection System for Small Motorcycles," Michihisa Nakamure, Yuuichirou Sawada, and Shigeki
Hashimoto, Yamaha Motor Co., Ltd., SAE Paper 2003-32-0084, September 2003,Docket Identification EPA-HQ-
OAR-2004-0008.
45. "Honda Releases the iGX440 Next-Generation General Purpose Engine with Electronic Control Technology-a
World's First," Honda Motor Co., Ldt., Press Release, April 20, 2005, Docket Identification EPA-HQ-OAR-2004-
0008.
46. "Honda's iGX Intelligent Engine," Honda Motor Co., Ldt., Product Information, April 2007, Docket
IdentificationEPA-HQ-OAR-2004-0008.
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47. "Evinrude E-TEC Presentation; Ann Arbor Michigan," presented to U.S. EPA by Fernando Garcia of BRP on
September 30, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0246.
48. "Exhaust Emissions from Marine Engines Using Alternate Fuels," Michigan Automotive Research Corporation,
Prepared for NMMA, October 8, 1992, Docket Identification EPA-HQ-OAR-2004-0008-0205.
49. "Effects of Transience on Emissions from Inboard Marine Engines," EPA memo by Mike Samulski, May 30,
1996, Docket Identification EPA-HQ-OAR-2004-0008-0209.
50. Letter from Jeff Carmody, Santa Barbara Air Quality management District, to Mike Samulski, U.S. EPA, July
21, 1997, Docket Identification EPA-HQ-OAR-2004-0008-0193.
51. "National Marine Manufacturers Association's Small Business Boat Builder and Engine Manufacturers
Comments in Response to EPA's Initial Regulatory Flexibility Analysis Regarding EPA's Plans to Propose
Emission Regulations for Recreational Marine Gas and Diesel Powered Sterndrive/Inboard Engines," July 12, 1999,
Docket Identification EPA-HQ-OAR-2004-0008-0213.
52. "Emissions from Marine Engines with Water Contact in the Exhaust System," Mace, et. al., SAE Paper 980681,
1998, Docket Identification EPA-HQ-OAR-2004-0008-0219.
53. "Marine Gasoline Engine Testing," Carroll, J., White, J., Southwest Research Institute, Prepared for U.S. EPA,
September, 2001, Docket A-2000-01, Docket Identification EPA-HQ-OAR-2004-0008-0253.
54. "Marine Gasoline Engine and Boat Testing," Carroll, J., Southwest Research Institute, Prepared for U.S. EPA,
September, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0254.
55. "Exhaust Emission Testing of Two High-Performance SD/I Marine Engines," EPA Memo from Mike Samulski
and Matt Spears, June 23, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0349.
56. Email from Mark Reichers, Mercury Marine, to Mike Samulski, US EPA, "1075 / 850 Test Data," June 9, 2005,
Docket Identification EPA-HQ-OAR-2004-0008-0295.
57. Email from Mark Reichers, Mercury Marine, to Mike Samulski, US EPA, "525 EFI Baseline Emissions Data,"
June 10, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0296.
58. "EGR Test Data from a Heavy-Duty Gasoline Engine on the E4 Duty Cycle," EPA Memo from Joe McDonald
and Mike Samulski, July 12, 1999, Docket Identification EPA-HQ-OAR-2004-0008-0199.
59. "Marine Gasoline Engine Testing," Carroll, J., White, J., Southwest Research Institute, Prepared for U.S. EPA,
September, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0253.
60. "Marine Gasoline Engine and Boat Testing," Carroll, J., Southwest Research Institute, Prepared for U.S. EPA,
September, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0254.
61. "Marine Gasoline Engine Testing," Carroll, J., White, J., Southwest Research Institute, Prepared for U.S. EPA,
September, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0253.
62. "Summary of SwRI Project for CARD entitled, 'Development of Low Emissions SD/I Boats," White, J.,
Southwest Research Institute, August 14, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0263.
63. "Development of Low Emissions; SD/I Boats; Project Update," Carrol, J., Southwest Research Institute,
September 11, 2003, Docket Identification EPA-HQ-OAR-2004-0008-0264.
4-84
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Feasibility of Exhaust Emission Control
64. "Public Meeting to Consider a Status Report on Catalyst Testing of Spark-Ignition Inboard/Sterndrive
Pleasurecraft: Staff Report," State of California; Air Resources Board, October 28, 2004, Docket Identification EPA-
HQ-OAR-2004-0008-0236.
65. "Marine Gasoline Engine and Boat Testing," Carroll, I, Southwest Research Institute, Prepared for U.S. EPA,
September, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0254.
66. E-mail from Rich Waggoner, Indmar, to Mike Samulski, U.S. EPA, "SBREFA notes from Indmar," July 24,
2006, Docket Identification EPA-HQ-OAR-2004-0008-0438.
67. Garcia, A., Beamer, B., Earnest, G., "In Depth Survey Report of Carbon Monoxide Emissions and Exposures on
Express Cruisers Under Various Operating Conditions," National Institute for Occupational Safety and Health,
Report No. EPHB 289-1 la, January 2006, Docket Identification EPA-HQ-OAR-2004-0008-0396.
68. Garcia, A., Beamer, B., Earnest, G., "In Depth Survey Report of Carbon Monoxide Emissions and Exposures on
Express Cruisers Under Various Operating Conditions," National Institute for Occupational Safety and Health,
Report No. EPHB 289-1 la, January 2006, Docket Identification EPA-HQ-OAR-2004-0008-0396.
69. "Summary of Government/Industry Carbon Monoxide Workshop and Two Follow-Up Meetings," Memo from
Mike Samulski, U.S. EPA to Docket OAR-2004-0008, March 31, 2004, Docket Identification EPA-HQ-OAR-2004-
0008-0008.
70. "Carbon Monoxide Follow-up Meeting; Miami FL - IBEX Show; Minutes," American Boat and Yacht Council,
October 19, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0286.
71. "News Release: Floating Environmental Laboratory Demonstrates Westerbeke's Safe-CO™ Ultra-Low CO
Emissions," Westerbeke Engines & Generators, September 26, 2005, Docket Identification EPA-HQ-O AR-2004-
0008-0298.
72. "Create the Right Atmosphere; Kohler Marine Generators Helping Make Boating Safer," Presented by Kohler
Power Systems at the 2005 International Boatbuilders' Exhibition and Conference, October 20, 2005, Docket
IdentificationEPA-HQ-OAR-2004-0008-0292.
73. Zimmer, A., Earnest, G., Kurimo, R., "An Evaluation of Catalytic Emission Controls and Vertical Exhaust
Stacks to Prevent Carbon Monoxide Poisonings from Houseboat Generator Exhaust," National Institute for
Occupational Safety and Health, EPHB 171-36a, September 2005, Docket Identification EPA-HQ-OAR-2004-0008-
0397.
74. "Duty Cycle for Recreational Marine Engines," Morgan, E., Lincoln, R., SAE Paper 901596, 1990, Docket
IdentificationEPA-HQ-OAR-2004-0008-0216.
75. "Reciprocating Internal Combustion Engines - Exhaust Emission Measurement - Part 4: Test Cycles for
Different Engine Applications," ISO/DIS 8178-4, International Standards Organization, Docket Identification EPA-
HQ-OAR-2004-0008-0503.
76. Morgan, E., Lincoln, R., "Duty Cycle for Recreational Marine Engines," SAE Paper 901596, 1990, Docket
IdentificationEPA-HQ-OAR-2004-0008-0216.
77. Carroll, J., "Determination of Operating Ranges of Marine Engines," prepared by Southwest Research Institute
for the National Marine Manufacturers Association, August 2004, Docket Identification EPA-HQ-O AR-2004-0008-
0255.
78. Samulski, M., "Exhaust Emission Testing of a Two-Stroke and a Four-Stroke Marine Engine; Results and
Procedures," U.S. EPA, Memo to Docket #A-92-98, Docket Identification EPA-HQ-OAR-2004-0008-0097.
4-85
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Draft Regulatory Impact Analysis
79. Wasil, I, Montgomery, D., Strauss, S., Bagley, S., "Life Assessment of PM, Gaseous Emissions, and Oil Usage
in Modern Marine Outboard Engines," SAE-GRAZ 43, Society of Automotive Engineers International, 2004,
Docket Identification EPA-HQ-OAR-2004-0008-0262.
80. Klak, Joe, "Marine NTE Zones," Bombardier Recreational Products, October 26, 2006, Docket Identification
EPA-HQ-OAR-2004-0008-0508.
81. "Marine Gasoline Engine Testing," Carroll, I, White, I, Southwest Research Institute, Prepared for U.S. EPA,
September, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0253.
82. "Marine Gasoline Engine and Boat Testing," Carroll, I, Southwest Research Institute, Prepared for U.S. EPA,
September, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0254.
83. "Summary of SwRI Project for CARB entitled, 'Development of Low Emissions SD/I Boats," White, J.,
Southwest Research Institute, August 14, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0263.
84. "Development of Low Emissions; SD/I Boats; Project Update," Carrol, J., Southwest Research Institute,
September 11, 2003, Docket Identification EPA-HQ-OAR-2004-0008-0264.
85. "Marine Gasoline Engine Testing," Carroll, J., White, J., Southwest Research Institute, Prepared for U.S. EPA,
September, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0253.
86. Memorandum from Mark Wolcott to Charles Gray, "Ambient Temperatures Associated with High Ozone
Concentrations," U.S. EPA, September 6, 1984, Docket Identification EPA-HQ-OAR-2004-0008-0235.
87. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
88. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
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Feasibility of Evaporative Emission Control
CHAPTER 5: Feasibility of Evaporative Emission Control
Section 213(a)(3) of the Clean Air Act presents statutory criteria that EPA must evaluate
in determining standards for nonroad engines and vehicles including marine vessels. The
standards must "achieve the greatest degree of emission reduction achievable through the
application of technology which the Administrator determines will be available for the engines
or vehicles to which such standards apply, giving appropriate consideration to the cost of
applying such technology within the period of time available to manufacturers and to noise,
energy, and safety factors associated with the application of such technology." This chapter
presents the technical analyses and information that form the basis of EPA's belief that the
proposed evaporative emission standards are technically achievable accounting for all the above
factors.
The proposed evaporative emission standards for Small SI equipment and Marine SI
vessels are summarized in the Executive Summary. This chapter presents available emissions
data on baseline emissions and on emission reductions achieved through the application of
emission control technology. In addition, this chapter provides a description of the proposed test
procedures for evaporative emission determination.
Evaporative emissions from equipment and vessels using spark-ignition (SI) engines can
be very high. This is largely because Small SI and Marine SI applications generally have fuel
tanks that are vented to the atmosphere and because materials used in the construction of the
plastic fuel tanks and hoses generally have high permeation rates. Evaporative emissions can be
grouped into five categories:
DIURNAL: Gasoline evaporation increases as the temperature rises during the day,
heating the fuel tank and venting gasoline vapors. We also include, under this heading, diffusion
losses which are vapors that will escape from an open vent even without a change in
temperature.
PERMEATION: Gasoline molecules can saturate plastic fuel tanks and rubber hoses,
resulting in a relatively constant rate of emissions as the fuel continues to permeate through these
components.
RUNNING LOSSES: The hot engine and exhaust system can vaporize gasoline when the
engine is running.
HOT SOAK: The engine remains hot for a period of time after the engine is turned off
and gasoline evaporation continues.
REFUELING: Gasoline vapors are always present in typical fuel tanks. These vapors are
forced out when the tank is filled with liquid fuel.
5-1
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Draft Regulatory Impact Analysis
5.1 Diurnal Breathing Loss Evaporative Emissions
In an open fuel tank, the vapor space is at atmospheric pressure (typically about 14.7 psi),
and contains a mixture of fuel vapor and air. At all temperatures below the fuel's boiling point,
the vapor pressure of the fuel is less than atmospheric pressure. This is also called the partial
pressure of the fuel vapor. The partial pressure of the air is equal to the difference between
atmospheric pressure and the fuel vapor pressure. For example, in an open-vented fuel tank at
60°F, the vapor pressure of typical gasoline would be about 4.5 psi. In this example, the partial
pressure of the air would be about 10.2 psi. Assuming that the vapor mixture behaves as an ideal
gas, then the mole fractions (or volumetric fractions) of fuel vapor and air would be equal to
their respective partial pressures divided by the total pressure; thus, the fuel would be 31 percent
of the mixture (4.5/14.7) and the air would be 69 percent of the mixture (10.2/14.7).
Diurnal emissions occur when the fuel temperature increases, which increases the
equilibrium vapor pressure of the fuel. For example, assume that the fuel in the previous
example was heated to 90°F, where the vapor pressure that same typical fuel would be about 8.0
psi. To maintain the vapor space at atmospheric pressure, the partial pressure of the air would
need to decrease to 6.7 psi, which means that the vapor mixture must expand in volume. This
forces some of the fuel-air mixture to be vented out of the tank. When the fuel later cools, the
vapor pressure of the fuel decreases, contracting the mixture, and drawing fresh air in through
the vent. When the fuel is heated again, another cycle of diurnal emissions occurs. It is
important to note that this is generally not a rate-limited process. Although the evaporation of
the fuel can be slow, it is generally fast enough to maintain the fuel tank in an essentially
equilibrium state.
As fuel is used by the engine, and the liquid fuel volume decreases, air is drawn into the
tank to replace the volume of the fuel. (Note: the decrease in liquid fuel could be offset to some
degree by increasing fuel vapor pressure caused by increasing fuel temperature.) This would
continue while the engine was running. If the engine was shut off and the tank was left
overnight, the vapor pressure of the fuel would drop as the temperature of the fuel dropped. This
would cause a small negative pressure within the tank that would cause it to fill with more air
until the pressure equilibrated. The next day, the vapor pressure of the fuel would increase as the
temperature of the fuel increased. This would cause a small positive pressure within the tank
that would force a mixture of fuel vapor and air out. In poorly designed gasoline systems, where
the engine or exhaust is very close to the fuel tank the engine/exhaust heating may cause large
amounts of gasoline vapor to be vented directly to the atmosphere.
Several emission-control technologies can be used to reduce diurnal evaporative
emissions. Many of these technologies would also control running loss and hot soak emissions
and some could be used to control refueling emissions. We believe manufacturers will have the
opportunity use a wide variety of technology approaches to meet the proposed evaporative
emission standards. The advantages and disadvantages of the various possible emission-control
strategies are discussed below. This section summarizes the data and rationale supporting the
diurnal emission standard for Marine SI vessels and Small SI equipment presented in the
Executive Summary.
5-2
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Feasibility of Evaporative Emission Control
5.1.1 Baseline Emissions
5.1.1.1 Marine Vessels
We tested two aluminum marine fuel tanks in their baseline configurations for diurnal
emissions. Aluminum fuel tanks were used so that permeation emissions would not occur during
the testing. The 17 gallon aluminum tank was constructed for this testing, but is representative
of a typical marine fuel tank; the 30 gallon aluminum tank was removed from an 18 foot
runabout. The fuel tanks were tested with the venting through a length of 5/8 inch hose to ensure
that the emissions measured were a direct result of the fuel temperature heating and not diffusion
through the vent (see Section 5.1.3). The advantage of using the aluminum fuel tanks for this
testing was to exclude permeation emissions from the measured results. All of the testing was
performed with fuel tanks filled to 40 percent of capacity with 9RVP1 test fuel.
The diurnal test results are presented in units of grams per gallon capacity of the fuel tank
per day. These units are used because gallons capacity is a defining characteristic of the fuel
tank. Diurnal vapor formation itself is actually a function of the vapor space above the fuel in
the fuel tank rather than the total capacity.
Table 5.1-1 presents the test results compared to anticipated results. The anticipated
results are based on the Wade model which is a set of theoretical calculations for determining
diurnal emissions based of fill level, fuel RVP, and temperature profile. These calculations are
presented in Chapter 3. Although the Wade model over-predicts the vapor generation, it does
show a similar trend with respect to temperature. To account for this over prediction, we use a
correction factor of 0.78. This correction factor is based on empirical data1, has historically been
used in our automotive emission models, and appears to be consistent with the data presented
below.
1 Reid Vapor Pressure (psi). This is a measure of the volatility of the fuel. 9 RVP represents a typical
summertime fuel in northern states.
5-3
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Draft Regulatory Impact Analysis
Table 5.1-1; Baseline Diurnal Evaporative Emission Results (varied temperature)
Temperatures
22-36°C (72-96°F)
22-36°C (72-96°F)
24-33°C (74-91°F)
22 - 30°C (71 - 86°F)
25-3TC (77-88°F)
26 - 32°C (78 - 90°F)
28-31°C(82-87°F)
Capacity
[gallons]
17
30
30
30
30
30
30
Measured
[g/gallon/day]
1.40
1.50
1.13
0.88
0.66
0.85
0.47
Wade Model
[g/gallon/day]
2.30
2.30
1.33
1.02
0.88
1.04
0.43
Corrected Wade
[g/gallon/day]
1.79
1.79
1.04
0.80
0.69
0.81
0.34
5.1.1.2 Small SI Equipment
We contracted with an outside lab for the testing of thirteen Small SI fuel tanks over
various test temperature profiles.2'3 This testing was performed with the tanks filled to 50
percent capacity with certification gasoline and is discussed in more detail below in the
Section 5.2.1. This data is presented in Table 5.1-2. In addition, in cases where the fuel
temperature profiles were within the input range of the Wade model for diurnal emissions,
theoretical emissions were also calculated using the same correction factor discussed above for
marine fuel tanks. As shown below, the measured values are fairly consistent with the
theoretical values.
5-4
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Feasibility of Evaporative Emission Control
Table 5.1-2: Fuel Temperature Measurements During Operation of Small SI Equipment
Equipment Type
Riding mower
Walk-behind
mower
Generator set
Pressure washer
Fuel Capacity
[gallons]
1.1
1.4x2
1.7
2.5
3.0
6.5
6.5x2
0.34
0.25
0.22
8.5
7.0
1.8
Temperature
Profile °C
15.7-28.4
21.9-29.7
19.5-30.3
27.0-35.0
26.6-28.4
24.3 -33.2
20.5-23.9
23.3 -33.0
28.7-46.7
28.7-59.7
20.6-25.8
25.8-50.0
19.0-50.6
Measured HC
grams/gallon
0.92
0.88
0.82
1.29
0.25
1.20
0.26
0.76
4.92
36.9
0.45
9.90
11.6
Theoretical HC
grams/gallon
0.91
0.71
0.94
1.16
0.17
1.08
0.23
1.18
NA*
NA*
0.38
NA*
NA*
* outside the temperature range of the model
The California Air Resources Board performed diurnal testing on seven pieces of
handheld equipment and 20 pieces of non-handheld equipment by placing the whole equipment
in a SHED.4 They filled the fuel tanks to 50 percent with 7 RVP fuel and tested over their 65-
105° F summer day test cycle. Because the entire piece of equipment was included in these
tests, not only were diurnal venting emissions measured, but tank and hose permeation as well
(plus any potential leaks). Average test results by equipment type are presented in Table 5.1-3.
Table 5.1-3: ARB Measurement of Evaporative Emissions from Small SI Equipment
(7 RVP California Certification Fuel, 50% Fill, 65-105°F)
Equipment Type
Handheld equipment
Walk-behind lawnmowers
Generators
Riding Mowers
Edgers
Tiller
Number of Data Points
7
12
2
O
2
1
Average Measured HC [grams/day]
1.04
3.51
11.2
8.70
1.53
4.12
5-5
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Draft Regulatory Impact Analysis
ARB also performed tests on a subset of the equipment using fuel containing MTBE and
fuel containing ethanol to investigate fuel effects. They observed nearly a 50 percent increase in
emissions when an ethanol blend was used compared to an MTBE blend. The reason for this
increase was not discussed, but may have largely been a permeation effect. On five pieces of
equipment, a California wintertime cycle (51.6-69.5° F) was used as well. As would be
expected, the emissions were reduced significantly. The theoretical models predict about an 85
percent reduction in diurnal venting emissions and about a 60 percent reduction in permeation.
The observed results were about a 70 percent reduction which is in this range.
5.1.2 Insulation of the Fuel Tank
The diurnal vapor generated in a fuel tank is directly related to the diurnal temperature
trace of the fuel. A reduction in temperature variation causes less vapor to be formed. To
investigate this effect we used insulation around the fuel tank to reduce the effect of the ambient
air temperature variation on the fuel temperature variation. In our preliminary testing, we
insulated a 23 gallon rotationally molded marine fuel tank using 3 inch thick construction foam
with an R-value of 15 as defined by 16 CFR 460.5. This testing was performed with the fuel
tank vent open to atmosphere. Table 5.1-4 presents the fuel temperatures and evaporative
emissions over the three day test.
We tested this fuel tank over a three day diurnal test with an ambient temperature of 72-
96°F. This experiment resulted in a 50 percent reduction in emissions from baseline on the
highest of these three test days. The baseline emissions were measured to be 2.5 g/gallon/day;
however it should be noted that for both the baseline test and the insulated tank tests we did not
control for permeation or diffusion. Over this test, the emissions decreased for subsequent days.
We believe this was due to the fuel temperature cycle stabilizing. Although we did not control
for permeation or diffusion, the results from this preliminary experiment directionally show the
effect of insulation on diurnal emissions.
Table 5.1-4: Evaporative Emission Results for Insulated Flat, Plastic Tank
Test Day
Day#l
Day #2
Day #3
SHED Temperature
22-36°C (72-96°F)
22-36°C (72-96°F)
22-36°C (72-96°F)
Fuel Temperature
22-28°C (72-82°F)
26-30°C (78-86°F)
26-30°C (80-86°F)
Evaporative HC
1.2g/gal/day
l.Og/gal/day
0.8 g/gal/day
In boats with installed fuel tanks, the fuel tank is generally hidden beneath the deck. As a
result, there is a certain amount of "inherent" insulation caused by the boat itself. This effect is
increased for a boat that is stored in the water. The water acts as a cooling medium for the fuel
tank, especially if it is installed in the bottom of the boat. In addition, the thermal inertia of the
fuel in the tank can act to dampen temperature variation imposed from the diurnal heating of the
ambient air. To investigate this effect, we tested several boats by recording the ambient air
5-6
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Feasibility of Evaporative Emission Control
temperature and fuel temperatures over a series of days. Two boats were tested on trailers
outside in the summer, two boats were tested on trailers in a SHED, and two boats were tested in
the water on summer days. Table 5.1-5 presents the average results of this testing. The
temperature traces are presented in Appendix 5 A.
Table 5.1-5: Ratio of Fuel to Ambient Temperature Swing for Boats
Boat Type
9 ft. personal watercraft
16 ft. jet boat
18 ft. runabout
16 ft. jet boat
18 ft. runabout
21 ft. deck boat
Test Conditions
outside, on trailer
outside, on trailer
in SHED, on trailer
in SHED, on trailer
outside, in water
outside, in water
Capacity
[gallons]
13
40
30
40
30
20
Fuel Tank
Fill Level
50%
50%
40%
90%
100%
90%
Temperature
Ratio*
66%
52%
68%
33%
19%
27%
* Average ratio of change in fuel temperature to change in ambient air temperature over test days.
In their comments on the proposed rule, the National Marine Manufacturers Association
presented temperature data on 18 foot runabout, with a 32 gallon tank, tested in a SHED with an
ambient temperature of 72-96°F.5 The average fuel to ambient temperature ratio was 54 percent
for this testing. This ratio is in the range of EPA test results for boats tested on a trailer.
Brunswick also included temperature data in their comments.6 The average days test on a boat
on the water was 19 percent, which is consistent with our water tests. Brunswick's average for
boats tested while stored out of the water was 27 percent which is considerably lower than the
EPA and NMMA testing. Combining all of the EPA and industry data, the average fuel to
ambient temperature ratio (based on test days) is about 20 percent for boats in the water and 50
percent for boats stored out of the water.
During diurnal testing of lawnmowers, ARB found that the fuel and tank skin
temperature follow the ambient temperature closely.7 This same phenomenon would be expected
for other Small SI equipment as well (and portable fuel tanks) because of the small fuel volumes
and because these tanks are generally exposed to ambient air. One issue that we considered was
that Small SI equipment is often stored in garages or sheds. In that case, we were interested in if
the garage or shed acts to insulate the fuel tanks from ambient temperature swings. ARB
collected data on four garages and one shed. This data included summer and winter California
temperature measurements. For each test, the inside and outside temperature were measured for
five days. This data is presented in Table 5.1-7. For the garages, the inside temperature was
generally warmer than outside, but the variable temperature swings were smaller. For the shed,
the inside temperature was warmer and showed higher heat builds than the outside temperature.
Table 5.1-6 also presents an estimate of the effect on diurnal emissions using the theoretical
5-7
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Draft Regulatory Impact Analysis
equations presented in Chapter 3. No conclusive evidence of was observed to suggest that these
fuel tanks are generally subject to inherent insulation.
Table 5.1-6: Comparison of Ambient to Inside Diurnal Temperature Swings
Season
Winter
Summer
Enclosure
garage D
garage G
garage J
garage A
garage D
garage G
garage J
shed
Inside Temperature °C
Avg T Avg Delta T
13.8
12.1
13.5
27.4
35.9
27.4
27.6
27.1
6.4
9.2
2.4
3.6
11.7
15.7
8.9
20.1
Outside Temperature °C
Avg T Avg Delta T
10.1
5.8
8.0
22.4
30.3
21.3
23.7
23.6
9.3
14.3
7.3
12.2
15.6
19.5
20.3
14.1
Emission
Effect
-8%
-9%
-55%
-63%
20%
23%
-61%
119%
Some of the variance between the fuel temperature and ambient temperature, especially
for larger fuel tanks, is likely due to the thermal inertia of the fuel in the tank. The fuel has mass
and therefore takes time to heat up. ARB performed a study in which the fuel temperature and
ambient temperature were recorded for aboveground storage fuel tanks.8'9 Three fuel tanks sizes
were included in the study: 350, 550, and 1000 gallons. Because of the large size of these tanks,
the thermal inertia effects would be expected to be larger than for typical fuel tanks used in
Marine SI and Small SI applications. For the 350 gallon fuel tank, ARB also measured the effect
of insulating the fuel tank on temperature. Table 5.1-7 presents the results of this testing. Note
that the test results are the average of five days. Ambient temperature on these test days
typically had a minimum in the 60-70°F range and a maximum temperature in the 95-105T
range.
EPA performed testing on 17 gallon marine fuel tank in a SHED over a single 72-96T
diurnal test and measured both ambient and fuel temperature.10 This data is also included in
Table 5.1-7. Note that for the smaller tank, there is little difference between the ambient and fuel
temperature profiles. However, for larger tanks, the fuel temperature has about a 25-30 percent
smaller temperature swing than the ambient temperature. Note that the insulated fuel tank had a
temperature ratio similar to the fuel tank stored in a boat in the water.
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Feasibility of Evaporative Emission Control
Table 5.1.7: Ratio of Fuel to Ambient Temperature for Uninsulated Fuel Tanks
Fuel Tank Type
marine fuel tank
aboveground storage tank
(with insulation)
aboveground storage tank
aboveground storage tank
Tank Capacity [gallons]
17
350
550
1000
Temperature Ratio*
95%
75%
(18%)
70%
76%
* Average ratio of change in fuel temperature to change in ambient air temperature over test days.
5.1.3 Diffusion Effect
For the purposes of this discussion, diffusion refers to the process in which gasoline
vapor penetrates air in an attempt to equalize the concentration throughout the gas mixture. This
transport phenomenon is driven by the concentration gradient and by effective area. In the case
of a mobile source fuel system that has a vent to atmosphere, the fuel vapor concentration is near
saturation in the fuel tank and near zero outside of the fuel system. Therefore, the diffusion rate
is primarily a function of the path between the fuel tank and atmosphere. The following equation
describes the relationship between the flux of gasoline vapor out of the tank, the concentration
gradient, and the vent path:
Flux =
mass
area X time
= Dx
AC
where: D = diffusion coefficient (constant)
AC = concentration gradient
Ax = path length
area = cross sectional area of vent
Based on the above equation, diffusion from a tank through a vent hose would be a
function of the cross-sectional area divided by the length of the hose. Therefore a longer hose
would theoretically limit fuel vapor venting due to diffusion. Whenever a hydrocarbon (HC)
molecule escapes from the fuel tank, a new molecule of air enters the fuel tank to replace the
escaped HC. This brings the concentration of HC vapor in the fuel tank out of equilibrium. To
balance the partial pressures in the fuel tank, more HC must evaporate as HC in the vapor space
is depleted. In this way, the vapor concentration in the fuel tank remains saturated.
5.1.3.1 Marine Fuel Tank Data
In testing diurnal emissions from fuel tanks with open vents, the configuration of the vent
can have a significant effect on the measured emissions due to the diffusion of vapor out of any
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Draft Regulatory Impact Analysis
opening in the fuel tank. Depending on the size and configuration of the vent, diffusion can
actually occur when the fuel temperature is cooling. Most marine vessels with an installed fuel
tank vent through a hose. As shown below this configuration can minimize diffusion.
To quantify the diffusion component for a typical fuel tank, we ran four 72-96°F diurnal
tests on a 17 gallon aluminum marine fuel tank using various configurations for venting The
first configuration was with the fuel cap cracked open and the vent sealed, the second
configuration was with a 68 cm length of vent hose, and the third configuration was with a 1000
micron (1 mm) limiting flow orifice in the vent opening. This 1000 micron orifice was large
enough to allow venting without any measurable pressure increase in the fuel tank during the
diurnal test. The fourth configuration was a combination of the limited flow orifice and the vent
hose. Table 5.1-8 presents the results of this testing.
Table 5.1-8: Diurnal Test Results with Varied Venting Configurations
Vent Configuration
cracked fuel cap
68 cm of 5/8" fuel hose
1000 micron orifice
1000
micron orifice + 68 cm of 5/8" fuel hose
Evaporative HC [g/gallon/day]
2.05
1.40
1.47
1.34
The above testing showed a 50 percent higher emission rate for the tank vented through a
cracked fuel cap compared to one vented through a hose. In the test with the cracked fuel cap,
an increase in HC concentration in the SHED was observed throughout the test, even when the
fuel temperature was cooling. For the other three tests, the HC concentration leveled off when
the temperature began to cool. This suggests that the difference in measured emissions of 0.6 -
0.7 g/gal/day was due to diffusion losses.
To further investigate this diffusion effect, we tested the 17 gallon aluminum tank with
several venting configuration, at two constant temperature settings. Under these conditions, all
of the measured evaporative emissions would be expected to be due to diffusion. As seen in
Table 5.1-9, diffusion can be very high with too large of a vent opening unless a vent hose is
used. The two lengths of vent hose tested did not show a significant difference in diffusion
emissions. We believe that the vent hose limits diffusion by creating a gradual gradient in fuel
vapor concentration.
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Feasibility of Evaporative Emission Control
Table 5.1-9: Constant Temperature Test Results with Varied Venting Configurations
Vent Configuration
1/2" ID. fitting
68 cm of 5/8" fuel hose
137 cm of 5/8" fuel hose
1000 micron orifice
22 °C (72°F)
Evaporative HC [g/gal/day]
5.65
0.11
0.07
0.28
36°C (96°F)
Evaporative HC [g/gal/day]
10.0
0.18
0.24
0.41
The above data suggest that, at least for open vent fuel systems, the size and
configuration of the venting system can have a significant effect on evaporative emissions. In
marine applications, there is typically a vent hose attached to the fuel tank. Diffusion emissions
appear to be minimal if the fuel tank is vented through a length of hose. This is probably
because the long residence times in the hose cause more opportunities for molecular collisions
which direct the HC molecules back towards the fuel tank.
One study looked at the evaporation of liquids from a tube filled to various fill heights.11
As the fill height decreased (effectively increasing the length of the tube above the liquid
surface) the evaporation quickly decreased. These results are consistent with the observed
effects of venting through a hose in our testing. Installed marine fuel tanks typically vent
through a hose to the outside of the boat; therefore, diffusion losses are likely relatively small for
these applications. Another study was performed on automotive fuel caps which suggests that a
crack in the gasket on the fuel cap of 1 percent of the gasket area can result in more than 2 grams
of HC emissions per day.12
5.1.3.2 Small SI Fuel Tank Data
For Small SI applications (and portable marine fuel tanks), the tanks are typically vented
through an opening in the fuel cap. Therefore, unless the cap is sealed, we would expect
diffusion emissions to occur. The above data suggest that diffusion can account for a significant
portion of the evaporative HC emissions measured from a metal tank with a small vent in the cap
over a 72-96°F diurnal test. Because diffusion would still occur at constant temperature, the
contribution of diffusion to measured diurnal emissions would increase, on a percentage basis, as
the diurnal temperature swing approached zero.
To investigate the effect of fuel cap design on diffusion for Small SI applications, we
implemented a test program which included four fuel tank configurations (one metal and three
plastic) and the corresponding fuel caps. These four fuel tanks were taken from lawnmowers
using engines from the three lawnmower engine manufacturers with the highest U.S. sales and
represent the majority of lawnmower fuel tanks on the market. Table 5.1-10 presents a
description of these fuel tanks.
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Draft Regulatory Impact Analysis
Table 5.1-10: Lawnmower Fuel Tanks Used in Diurnal/Diffusion Testing
Tank
BM
BP
HP
TP
Tank description
metal, 800 ml
plastic, 1175 ml
plastic, 950 ml
plastic, 920 ml
Fuel Cap Vent Description
Three 1/16" dia. holes drilled in top of cap. Four similar holes
drilled in fibrous gasket
Three torturous pathways through plastic gasket, with venting
between tank/cap threads. (Also performed test using a
modified cap similar to the cap used on the metal tank.)
Pinhole in gasket center leading to two indentations in rubber
gasket at mating surface, with venting between tank/cap threads
Four indentations in rubber gasket at mating surface, with
venting between tank/cap threads
We contracted with two outside laboratories to perform the diurnal/diffusion tests for the
Small SI equipment fuel tanks shown above.13'1445'16 In this effort, the fuel tanks were sealed,
except for the vents in the fuel cap, and filled to 40 percent of capacity with 9 RVP fuel. These
tanks were then tested in a mini-SHED over the EPA 72-96°F 24-hour diurnal test procedure.
To minimize the effect of permeation on the test results, new fuel caps and plastic fuel tanks
were used for each test that had not been exposed to fuel or fuel vapor prior to the test.
Under this testing, emissions continued to climb even when temperature was cooling
back from 96°F to 72°F. These emissions were clearly not driven by temperature, so they were
determined to represent diffusion emissions. Total diffusion for the test was determined by
recording the HC emissions that occurred during the last 12 hours of the test (during the cooling
event) and then multiplying these emissions by two to represent 24 hours. Although the peak
temperature occurs after nine hours, only the last 12 hours were used to ensure that the fuel in
the tank was not still heating due to a thermal time lag. Diffusion was then subtracted off the
total HC measurement to determine non-diffusion diurnal emissions. For the fuel cap with the
three holes drilled straight through it, the emissions were so high that it went out of measurement
range near the end of the tests performed by one of the contractors. However, all of the observed
diffusion rates were linear, making it simple to extrapolate the data where necessary. Table 5.1-
11 presents the diurnal and diffusion data from these tests and compares it to the theoretical
diurnal emissions using the Wade equations discussed above. Charts in Appendix 5B present the
time series of the measured HC compared to the mini-SHED temperature.
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Feasibility of Evaporative Emission Control
Table 5.1-11: Diurnal and Diffusion Emissions from Lawnmower Fuel Tanks (g/gal/day)
over a 72-96-72 °F (22.2-35.6-22.2 °C) Temperature Profile
Tank
BM
BP
BP cap 2*
HP
TP
Total HC
47.8
2.1
24.1
1.6
2.1
Diffusion
43.6
0.1
19.3
0.1
0.2
Diurnal
4.2
2.0
4.8
1.5
2.0
Wade Diurnal
1.8
1.8
1.8
1.8
1.8
modified to be similar to cap on metal tank (BM)
The fuel caps in the above table for the lawnmower tanks labeled as BM and BP cap 2
resulted in very high diffusion emissions. Although this fuel cap type is a common design used
in Small SI applications, it may represent one of the worst case configurations for diffusion.
There are three small holes in the cap itself, and four small holes in the fibrous material
imbedded in the inside of the cap. Presumably, this design was intended to minimize fuel from
splashing out of the tank while still allowing the tank to breathe to prevent pressure or vacuum
from occurring in the tank. Because the carburetor on this lawnmower is gravity fed, too much
vacuum in the fuel tank could cause the engine to stall from lack of enough fuel. The reason that
this may be a worst case configuration is that there is a direct (and relatively large) path for fuel
vapor to escape from the fuel tank.
The other three fuel cap designs were also from stock lawnmower fuel systems. In all
three of these designs, the venting occurred through small grooves in the gasket that seals the
mating between the fuel cap and the fuel tank. The venting then occurs through the thread paths
between the cap and tank. As a result, vapor and air must pass through a tortuous pathway to
enter or leave the tank. This tortuous pathway appears to limit diffusion in much the same way
as venting through a long hose does.
The above emission testing was repeated except that the vents in the fuel cap were sealed
and the tank was vented through a 8 inch length of 1/4" ID. hose. A lawnmower air intake filter
was attached to the end of this hose in order to simulate the venting configuration on a
lawnmower with running loss control. To minimize the effect of permeation, a low permeation
barrier hose was used that had never before been exposed to fuel or fuel vapor. The test results
in which the tanks were vented through hoses are presented in Table 5.1-12.
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Draft Regulatory Impact Analysis
Table 5.1-12: Diurnal and Diffusion Emissions from Lawnmower Fuel Tanks (g/gal/day)
with Modified Venting Through Hose/Air Filter to Simulate Running Loss Control
over a 72-96-72 °F (22.2-35.6-22.2 °C) Temperature Profile
Tank
BM
BP
BP cap 2*
HP
TP
Total HC
vent through stock cap
47.8
2.1
24.1
1.6
2.1
Total HC
vent through hose/filter
12.9
1.9
1.9
2.0
2.9
Reduction in
Total HC
34.8
0.2
22.2
(0.4)
(0.7)
* modified to be similar to cap on metal tank (BM)
As shown in the table above, venting through the hose greatly reduced the measured
emissions compared to the BM cap vent. When vented through the hose configuration, diffusion
emissions were on roughly the same order as when the tortuous cap vents were used. This is
consistent with the data presented earlier on marine fuel tanks vented through a hose. In an in-
use running loss system, a valve or limited flow orifice would likely also be in the vent line.
These components would likely further reduce, or even eliminate, diffusion emissions.
There was some concern that diffusion may have been underestimated in the above tests
because air flowing back into the fuel tank during the cooling period may have limited diffusion
by pulling HC molecules back into the fuel tank. In addition, we believed that testing at constant
temperature would allow us to more directly measure diffusion. Therefore, the above testing
was repeated at a constant temperature of 29°C.17'18'19 However, it should be noted that this
testing may have overestimated diffusion somewhat because of small temperature fluctuations
(less than 0.5 °C) around the average during the test. Therefore, any HC measurements from the
"constant" temperature testing may have overstated diffusion due to vapor generated by the
repeated mini-diurnal cycles during in the test. These test results are presented in Table 5.1-13.
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Feasibility of Evaporative Emission Control
Table 5.1-13: Isothermal [29 °C] Diurnal and Diffusion Emissions from
Lawnmower Fuel Tanks (g/gal/day) with Modified Venting
Through Hose/Air Filter to Simulate Running Loss Control
Tank
BM
BP
BP cap 2*
HP
TP
Total HC
vent through stock cap
43.2
1.3
29.3
1.0
0.9
Total HC
vent through hose/filter
8.9
1.0
1.0
0.8
0.9
Reduction in
Total HC
34.3
0.3
28.3
0.2
0.0
* modified to be similar to cap on metal tank (BM)
At constant temperature, the relationship between measured diffusion emissions between
the venting configurations was consistent with the variable temperature testing. However, the
indicated diffusion results were somewhat higher. These higher results were influenced by two
effects. In the variable temperature testing, the diffusion was measured during the cooling
period when air was being drawn into the fuel tank. This would reduce diffusion into the SHED
because escaping HC molecules would need to overcome the air flow into the tank. At the same
time, the constant temperature test may have overstated diffusion due to the measured small
fluctuations in temperature that may have caused mini-diurnal cycles. Likely, the actual
diffusion rates are somewhere in-between the results presented in Tables 5.1-11 and 5.1-12.
Appendix 5B contains data charts that present the results of the Small SI diffusion testing in
more detail.
Although the results are presented above on a gram per gallon basis for comparison with
diurnal emissions, diffusion appears to be more a function of orifice size that fuel tank size.
Presumably, the diffusion rate on a grams per day basis would be the same through a given
orifice regardless of size of the vapor space. This is reflected in the data above in that the
permeation rates on a gram per gallon basis from the lawnmower fuel tanks with holes in the fuel
cap were much larger than for the marine fuel tank in the testing discussed earlier. At the same
time, larger fuel tanks may be designed with larger orifice sizes to account for higher amounts of
vapor expansion in the tank.
5.1.4 Carbon Canister
The primary diurnal evaporative emission control device used in automotive applications
is a carbon canister. With this technology, vapor generated in the tank is vented through a
canister containing activated carbon (similar to charcoal). The fuel tank must be otherwise
sealed; however, this only results in a minimal amount of pressure in the tank. The activated
carbon collects and stores the hydrocarbons. Once the engine is running, purge air is drawn
through the canister and the hydrocarbons are burned in the engine. These carbon canisters
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Draft Regulatory Impact Analysis
generally are about a liter in size for an automotive tank and have the capacity to store three days
of vapor over the test procedure conditions. For automotive applications, this technology
reduces diurnal emissions by more than 95 percent.
In a marine application, the vessel may sit for weeks without an engine purge; therefore,
canisters were not originally considered to be a practical technology for controlling diurnal vapor
from boats. Since that time, however, we have collected information showing that, during
cooling periods, the canister is purged sufficiently enough so that it can be used effectively to
reduce diurnal emissions. When the fuel in the tank cools, fresh air is drawn back through the
canister into the fuel tank. This fresh air will partially purge the canister and return
hydrocarbons back to the fuel tank.20'21 Therefore, the canister will have some open sites to
collect vapor during the next heating event. Test data presented below show that a canister that
starts empty is more than 90 percent effective at capturing hydrocarbons until it reaches
saturation. Once the canister reaches saturation, it is still capable of achieving more than a 60
percent reduction in diurnal emissions due to passive purging. Passive purging occurs as a result
of fresh air that is pulled through the canister during fuel tank cooling periods. With the addition
of an engine (active) purge, greater reductions would be expected.
We tested a 30 gallon aluminum fuel tank over three, multiple-day diurnal cycles with
and without a charcoal canister. The carbon canister was 2.1 liters in size with a butane working
capacity (BWC) of 11 g/dL (based on EPA test) and was aged using multiple 24 hour diurnal
cycles prior to testing. In our first test, the fuel temperature was cycled from 72-96°F using a
heating blanket in a SUED for at total of 28 days. Because we were not able to test over
weekends, we brought the fuel temperature down to 72°F and held it to prevent the generation or
purging of vapors. On Mondays, we saw higher vapor rates than the rest of the week which was
likely due to the vapor redistributing itself equally through the canister over the weekend when
the temperature was held constant. Under normal conditions, the continued diurnal cycles would
maintain a gradient through the canister and this effect would not occur. Appendix 5C contains
graph showing the results of the 28 day test. This test is interesting because we began with a
purged canister and were able to observe the loading of the canister over the first few days. It
took about five test days to achieve canister breakthrough and another ten test days before the
canister loading/purging cycle stabilized.
Once the canister was saturated, the emissions results stabilized. Therefore, for the
subsequent canister tests, we began with a loaded canister and tested for four days. The results
were collected beginning after the first night so that the canister would have a cooling cycle for
back-purge. Table 5.1-14 presents our test results for the baseline and stabilized with canister
diurnal emission rates.
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Feasibility of Evaporative Emission Control
Table 5.1-14: EPA Diurnal Emission Test Results With and Without a Canister
on a 30 Gallon Aluminum Marine Fuel Tank [g/gal/day]
Temperature Range
22.2-35.6°C (72-96°F)
25.6-32.2°C (78-90°F)
27.8-30.6°C (82-87°F)
Baseline
1.50
0.85
0.47
With a Canister
0.52
0.28
0.14
Reduction
65%
67%
71%
Marine manufacturers raised the concern that the high humidity in the areas where boats
are used would be detrimental to this technology. They stated that the carbon could become
saturated with water vapor, thereby reducing the available sites for hydrocarbon capture. These
manufacturers also commented that carbon canisters may not be able to survive shocks and
vibration that would be seen on a boat. Carbon canisters have been used in automotive
applications for decades, which are subject to high humidity (rainy days) and shocks and
vibration. In addition, one manufacturer, who is a primary supplier to the automotive industry,
has developed a new grade of carbon that has low moisture adsorption characteristics and about
40 percent harder than typical automotive carbon.22'23 This carbon has been designed specifically
for marine applications. Based on this manufacturer's testing, more than a 60 percent reduction
in diurnal vapor emissions can be achieved with a passive purge system. This reduction is based
on a canister capacity of 0.03 to 0.04 liters of carbon per gallon of fuel tank capacity.
The National Marine Manufacturers Association has initiated a test program has to
demonstrate the durability of carbon canisters in marine applications. This test program includes
installing carbon canisters on a total of fourteen boats made by four boat builders.24 These boat
types include cruisers, runabouts, pontoon boats, and fishing boats. The carbon canister design
used for these boats is a simple cylinder that can be cut to length with end caps and mounting
brackets. The canisters were installed in the vent lines and a valve was added to prevent fuel
from reaching the canister during refueling. These canisters use marine grade carbon. At the
end of this test program, each of the canisters were tested for working capacity and each canister
showed good performance.25 These canisters will be evaluated further, including destructive
testing.
Another issue that has been raised has been the ability of carbon canisters to pass the
Coast Guard flame test. The carbon canisters could be made out of a variety of materials,
including metal. Even a thin-walled nylon fuel tank could be manufactured to pass the flame test
if a flame-resistant coating or cover were used. One study attempted to ignite a carbon canister
that was loaded with fuel vapor.26 When an ignition source was applied to the canister vent, the
gases exiting the canister were ignited and burned as a small, steady flame until the canister tube
opening began to melt. No explosion occurred.
Recently, the California Air Resources Board (ARB) performed similar testing on a
commercial mower and a generator with 6 gallon fuel tanks and 0.65 liter canisters.27 Their
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Draft Regulatory Impact Analysis
testing showed better than 50 percent reductions, on average, in diurnal emissions through the
use of canisters without an engine purge. The testing was performed over two diurnal
temperature ranges, 53-71°F and 65-105°F which are intended to represent an average day and a
high temperature episode.
Over a decade ago, testing performed on a car showed similar results.28 A 1988 Regency
98 with an 18 gallon fuel tank was subjected to an 8 day diurnal without driving. This diurnal
was performed using a 72-96°F temperature profile, a tank filled to 40 percent with 9RVP
gasoline, and a purged canister at the beginning of testing. The test results showed, that the
canister loading/purging cycle began to stabilize after 6 days. Due to the canister back-purge,
the stabilized diurnal emission rate about 11.5 grams per day which was more than a 50 percent
reduction compared to baseline.
A manufacturer of activated carbon performed studies of ethanol fuel blend and carbon
bed temperature on carbon efficiency.29 Testing was performed with carbon canisters using
gasoline, E10, and E85 fuel for onboard vapor refueling emissions efficiency. The emissions
control was similar for each of the test fuels. Testing was also performed to measure gasoline
working capacity for carbon soaked at temperatures ranging from 25 to 80°C. Over this range
only a 10 percent decrease in working capacity was observed with increasing temperature. Over
the 25-40°C range, which is more representative of boat or Small SI equipment use, the effect
was only 1-2 percent. Based on the results from these studies, carbon canister efficiency would
be expected to be effective at reducing diurnal emissions over the range of fuels and
temperatures that may be seen in use.
5.1.5 Sealed System with Pressure Relief
Evaporative emissions are formed when the fuel heats up, evaporates, and passes through
a vent into the atmosphere. By closing that vent, evaporative emissions are prevented from
escaping. However, as vapor is generated, pressure builds up in fuel tank. Once the fuel cools
back down, the pressure subsides. One way to control these emissions is to seal the fuel system.
However, depending on the fuel tank design, a pressure relief valve may be necessary which
would limit the control.
5.1.5.1 Pressure Relief Valve
For most marine applications, U.S. Coast Guard safety regulations require that fuel tanks
be able to withstand at least 3 psi and must be able to pass a pressure impulse test which cycles
the tank from 0 to 3 psi 25,000 times (33 CFR part 183).2 The Coast Guard also requires that
these fuel tanks must be vented such that the pressure in the tank in-use never exceeds 80 percent
of the pressure that the tank is designed to withstand without leaking. The American Boat and
2 These regulations only apply to boats with installed fuel tanks and exclude outboard boats.
However, ABYC recommended practice effectively extends many of these requirements to outboard
boats as well.
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Feasibility of Evaporative Emission Control
Yacht Council makes the additional recommendation that the vent line should have a minimum
inner diameter of 7/16 inch.30 However, these recommended practices also note that "there may
be EPA or state regulations that limit the discharge of hydrocarbon emissions into the
atmosphere from gasoline fuel systems. The latest version of these regulations should be
consulted."
To prevent pressure from building too high in marine tanks, we first considered a 2 psi
pressure relief valve. This is a typical automotive rating and is below the Coast Guard
requirements. With this valve, vapors would be retained in the tank until 2 psi of pressure is
built up in the tank due to heating of the fuel. Once the tank pressure reached 2 psi, just enough
of the vapor would be vented to the atmosphere to maintain 2 psi of pressure. As the fuel cooled,
the pressure would decrease. In our August 14, 2002 proposal (67 FR 53050) we considered
standards based on a 1 psi valve which would only achieve a modest reduction over the proposed
test procedure. However this reduction would be significantly greater in use because the test
procedure is designed to represent a hotter than average day. On a more mild day, there would
be less pressure buildup in the tank and the valve may not even need to open. With the use of a
sealed system, a low pressure vacuum relief valve would also be necessary so that air could be
drawn into the tank to replace fuel drawn from the tank when the engine is running.
Manufacturers of larger plastic fuel tanks have expressed concern that their tanks are not
designed to operate under pressure. For instance, although they will not leak at 3 psi,
rotationally molded fuel tanks with large flat surfaces could begin deforming at pressures as low
as 0.5 psi. At 2.0 psi, the deformation would be greater. This deformation would affect how the
tank is mounted in the boat. Also, fuel tank manufacturers commented that some of the fittings
or valves used today may not work properly under 2 psi of pressure. Finally, they commented
that backup pressure-relief valves would be necessary for safety. For smaller fuel tanks, such as
used in personal watercraft, portable fuel tanks, and Small SI equipment, pressure is less of an
issue because of the smaller internal surface area of these fuel tanks. In addition, the
construction of these fuel systems are generally vertically integrated which allows for more
precise control of design parameters. For instance, personal watercraft manufacturers are
already sealing their fuel systems to prevent fuel from spilling into the water. These systems
generally have pressure relief valves ranging from 0.5 to 4.0 psi. In addition, portable fuel tanks
are designed to be sealed without any pressure relief.
We looked at two types of pressure relief strategies: pressure relief valves and limited
flow orifices. Because the Coast Guard requires that fuel systems not exceed 80 percent of their
design capacity of 3 psi, we only looked at pressure relief strategies that would keep the pressure
below 2.4 psi under worst case conditions.
For the pressure relief valve testing, we looked at several pressures ranging from 0.5 to
2.25 psi. The 2.25 psi valve was an off-the-shelf automotive fuel cap with a nominal 2 psi
pressure relief valve and 0.5 psi vacuum relief valve. For the other pressure settings, we used
another automotive cap modified to allow adjustments to the spring tension in the pressure relief
valve. We performed these tests on the 17 gallon aluminum fuel tank to remove the variable of
permeation. Emissions were vented through a hose to prevent diffusion losses from affecting the
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Draft Regulatory Impact Analysis
measurements. We operated over two temperature profiles. The first set of tests were performed
in a variable temperature SHED with a 72-96°F air temperature profile. This temperature profile
was based on the existing automotive cycle which is intended to represent a typical summer day
on which a high ozone event may occur. The second set of tests were performed using a heating
blanket to create a 78-90°F fuel temperature profile. This testing was intended to represent a
fuel tank in a boat, where the tank may be inherently insulated, during the same ambient
temperature profile. This inherent insulation creates a time lag on the heating and cooling of the
fuel and reduces the amplitude of the temperature profile by half.
As shown in Figure 5.1-1, there was a fairly linear relationship between the pressure
setting of the valve and the emissions measured over the proposed test procedure. In addition,
the slopes of the lines are similar for both test temperature scenarios. This suggests that over a
smaller temperature profile, a greater percent reduction in HC can be achieved at a given
pressure setting. This is reasonable because, in each case, a constant amount of vapor is
captured. In other words, regardless of the temperature profile, the same amount of vapor must
be generated to create a given pressure. For instance, with a 1 psi valve, about 0.4 grams/gallon
of HC are captured over each temperature profile. However, this represents a 50 percent
reduction over a 78-90°F temperature profile while only about a 25 percent reduction over the
72-96°F temperature profile.
Figure 5.1-1: Effect of Pressure Cap on Diurnal Emissions
0.0
0.5 1.0 1.5
pressure relief setting [psi]
2.0
2.5
The California Air Resources Board tested a lawnmower in a SHED for diurnal
emissions in a baseline configuration, a sealed system, and with various pressure relief settings.31
Because the whole lawnmower was tested, permeation (and potentially leakages) were measured
as well as diurnal venting emissions. The testing was performed over a 65-105°F temperature
cycle with the fuel tank filled to 50 percent with 7 RVP fuel. For the system as a whole, they
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Feasibility of Evaporative Emission Control
measured a 76 percent reduction in emissions when the tank was fully sealed compared to the
open vent configuration. This suggests that diurnal venting made up about 76 percent of the
evaporative emissions measured. Testing using 2, 3, and 4 psi pressure relief valves showed
reductions of 43 percent, 43 percent, and 63 percent respectively. They also collected pressure
data over various diurnal temperature cycles on a lawnmower fuel tank. Over the 65-105°F
cycle, the measured a pressure increase of about 2.5 psi. Even under an extreme cycle of 68-
121°F, the measured increase in tank pressure was about 3.6 psi.
5.1.5.2 Limited Flow Orifice
Another strategy for maintaining a design pressure is to use a limited flow orifice on the
vent. In our testing, we are looked at three orifice sizes: 25, 75, and 1,000 microns in diameter.
Again, we performed tests over a 72-96°F diurnal using a 17 gallon aluminum tank. To get these
exact orifice sizes, we ordered from a company that specializes in boring holes with a laser
device. These orifices were relatively inexpensive. It should be noted that a smaller tank would
need a smaller orifice and a larger tank could use a larger orifice to build up the same pressure in
the tank. The test results are presented in Table 5.1-15. For all of the tests with the limited flow
orifices, no vent hose was attached.
Table 5.1-15: Diurnal Evaporative Emissions with Limited Flow Orifices
Orifice Diameter (microns)
baseline (open vent with hose)
1000
75
25
Peak Pressure [psi]
0.0
0.0
1.6
3.1
Evaporative HC [g/gallon/day]
1.40
1.47
1.16
0.24
By limiting the flow of the vapor from the tank, emissions were reduced with some
pressure build up in the tank. However, because the vapor is flowing from the tank even at low
pressure, this strategy is less effective for reducing diurnal emissions than a pressure relief valve.
Generally, a higher peak pressure is necessary with the LFO for a given emission reduction. In
addition, the limited flow orifice would have to be sized for worst case conditions to prevent the
tank from reaching too high of a pressure. A LFO sized for worst case conditions would be less
effective under typical conditions because the vapor flow out of the tank could be too low for the
LFO to create a restriction. In comparison, a pressure relief valve would achieve higher percent
reductions under typical conditions than for worst case conditions because the valve would open
less often.
5.1.5.3 Vacuum Relief Valve
For some fuel tanks, pressure relief is not necessary. An example of this is portable
marine fuel tanks which are currently equipped with a manual sealing valve. This valve can be
5-21
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Draft Regulatory Impact Analysis
sealed by the operator during storage to prevent vapor from escaping. Although pressure will
build up during diurnal heating, the fuel tanks are designed to withstand this pressure. However,
the valve must be opened by the operator during engine operation so that a vacuum does not
form in the fuel tank as fuel is drawn to the engine. If this vacuum were to become too high, it
could cause the engine to stall by restricting fuel to the engine.
The existing design requires that the operator close the valve whenever the engine is not
running for diurnal emissions to be controlled. If an automatic vacuum relief valve were used,
then the operator would not need to operate the sealing mechanism. It would always control
diurnal (and other breathing loss) emissions. At the same time, the vacuum relief valve would
allow air to be drawn into the fuel tank when the engine is operating to prevent a significant
vacuum from being formed.
One manufacturer's approach to this automatic valve design is to use a diaphragm valve
such as those used in automotive fuel systems.32 This inexpensive design would be able to seal
the tank under pressure, yet open at very low vacuums. This design (or other vacuum relief
valve designs) could be used in any nonroad application where the fuel system is able to
withstand pressure.
5.1.6 Selective Permeability Membrane
Another approach we investigated was fitting a molecular membrane in the vent line.
The theory was that the membrane would allow oxygen and nitrogen to pass through, but block
most longer-chain hydrocarbon molecules. We used a membrane fabricated using Teflon AF®
which is an amorphous fluoropolymer. Because oxygen and nitrogen (and some smaller
hydrocarbons) can pass through the membrane, hydrocarbons can be trapped in the fuel tank.
However, the process for molecules passing through the membrane is slow, so it is important to
size the membrane properly to prevent pressure build-up. This membrane could be placed in the
vent line or directly in an opening in the top of the fuel tank.
Similar membranes are already used for several applications. One manufacturer provides
membranes for a variety of uses such as oxygen or nitrogen enrichment of air or for separation of
hydrocarbons from air.33 One of these uses is to act as a vapor processor to prevent hydrocarbon
vapor from escaping from retail gasoline stations in California.34 Another membrane used for
similar applications allows hydrocarbons to permeate but blocks smaller gases. This membrane
is used in hydrocarbon recovery applications.35 In the above noted applications, the membranes
are typically used with a pump to provide a pressure drop across the membrane which causes
permeation through the membrane. Typically, adequate mixing is needed to maintain an
efficient diffusion rate.
We tested an amorphous fluoropolymer membrane with a surface area of about 40 cm2 in
the vent line of both a 30 and a 17 gallon aluminum fuel tank over three temperature cycles. The
membrane was applied to a wire mesh in a cylindrical shape with the an outside diameter not
much larger than the vent hose. Hydrocarbon emissions and fuel tank pressure were measured.
Over these tests we consistently saw a pressure build up, even over a 24 hour test. To investigate
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Feasibility of Evaporative Emission Control
the impacts of surface area, we increased the surface area by using 3 filters in parallel (single
vent line to assembly). Our test results suggest that the pressures associated with this technology
are comparable with the pressure relief valves needed to achieve the same reductions. However,
this technology may have the potential for meeting our proposed standards if used in conjunction
with a pump to provide a pressure differential across the filter without allowing pressure (and
mixing) to build up in the fuel tank. Our test results are presented in Table 5.1-16.
Table 5.1-16: Diurnal Venting Emissions with Selective Permeable Membranes
Tank Size
[gallons]
30
17
Venting
open
1 filter
3 filters
open
3 filters
72-96°F
g/gal/day psi
1.50
0.24
0.39
1.40
0.45
0
2.9
2.2
0
2.1
78-90°F
g/gal/day psi
0.85
0.14
-
—
0.30
0
1.5
-
—
1.2
81.6-86.4°F
g/gal/day psi
0.47
0.19
-
—
-
0
0.6
-
—
-
5.1.7 Volume Compensating Air Bag
Another concept for minimizing pressure in a sealed fuel tank is through the use of a
volume compensating air bag.36 The purpose of the bag is to fill up the vapor space in the fuel
tank above the fuel itself. By minimizing the vapor space, less air is available to mix with the
heated fuel and less fuel evaporates. As vapor is generated in the small vapor space, air is forced
out of the air bag, which is vented to atmosphere. Because the bag collapses as vapor is
generated, the volume of the vapor space grows and no pressure is generated.3 Once the fuel
tank cools as ambient temperature goes down, the resulting vacuum in the fuel tank will open the
bag back up.
We tested a 6 gallon portable plastic fuel tank with a 1.5 gallon volume compensating
bag made out of Tedlar. Tedlar is a light, flexible, clear plastic which we use in our labs for
collecting exhaust emissions samples. In our testing, the pressure relief valve never opened
because the volume compensating bag was able to hold the vapor pressure below 0.8 psi for each
of the three days. This testing supports the theory that a volume compensating bag can be used
to minimize pressure in a fuel tank, which in turn, reduces emissions when used in conjunction
with a pressure relief valve.
We did see an emission rate of about 0.4 g/gal/day over the 3 day test. The emission rate
was fairly constant, even when the ambient temperature was cooling during the test. This
suggests that the emissions measured were likely permeation through the tank. Other materials
3 The Ideal Gas Law states that pressure and volume are inversely related. By increasing the volume of the
vapor space, the pressure can be held constant.
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Draft Regulatory Impact Analysis
may be more appropriate than Tedlar for the construction of these bags. The bags would have to
hold up in a fuel tank for years and resist permeation while at the same time be light and flexible.
One such material that may be appropriate would be a fluorosilicon fiber.
5.1.8 Bladder Fuel Tank
Probably the most effective technology for reducing evaporative emissions from fuel
tanks is through the use of a collapsible fuel bladder. In this concept, a non-permeable bladder
would be installed in the fuel tank to hold the fuel. As fuel is drawn from the bladder, the
vacuum created collapses the bladder. Therefore, there is no vapor space and no pressure build
up. Because the bladder would be sealed, there would be no vapors vented to the atmosphere.
In addition, because there is no vapor space, vapor is not displaced during refueling events. We
have received comments that bladder tanks would be cost prohibitive because its use would
increase tank costs by 30 to 100 percent depending on tank size. However, bladder fuel tanks
have positive safety implications as well and are already sold by at least one manufacturer to
meet market demand in niche applications. Information on this system is available in the
docket.37
We tested a marine bladder fuel tank in our lab for both diurnal and permeation
emissions. Over the diurnal test procedure we saw an emission rate of 0.2 g/gal/day. Because
the system was sealed, this measured emission rate was likely due to permeation through the
bladder and not due to diurnal losses. We later tested the bladder fuel tank for permeation
emissions at 29°C and measured a permeation rate of 0.46 g/gal/day. The bladder used in our
testing was constructed out of polyurethane. The manufacturer of this bladder tank is now
working with a lower permeability material known as THV. THV is a fluoropolymer that can be
used to achieve more than a 95 percent reduction in permeation from current bladder fuel tanks
made out of polyurethane.38 In addition, THV is resistant to ethanol. Permeation rates for these
materials are presented in Appendix 5D.
5.1.9 Floating Fuel and Vapor Separator
Another concept used in some stationary engine applications is a floating fuel and vapor
separator. Generally small, impermeable plastic balls are floated in the fuel tank. The purpose
of these balls is to provide a barrier between the surface of the fuel and the vapor space.
However, this strategy does not appear to be viable for fuel tanks used in mobile sources.
Because of the motion of Small SI equipment and Marine SI vessels, the fuel sloshes and the
barrier would be continuously broken. Even small movements in the fuel could cause the balls
to rotate and transfer fuel to the vapor space. In addition, the unique geometry of many fuel
tanks could case the balls to collect in one area of the tank. However, we do not preclude the
possibility that some form of this approach could be made to work effectively in some mobile
source applications.
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Feasibility of Evaporative Emission Control
Figure 5.1-2: Liquid Vapor Trap
vent
5.1.10 Liquid Vapor Trap
One company has developed a
liquid vapor trap that it refers to as a
fuel vapor containment system (VCS).39
The VCS behaves similar to a liquid
trap used in sink drains in that trapped
liquid creates a barrier to gases. This
trap would be placed in the vent line to limit fuel vapor emitted from the fuel tank. Figure 5.1-2
presents an illustration of the basic concept.
When the temperature in the fuel tank increases, the vapor would expand in the fuel tank.
The fuel vapor would enter chamber A and force more of the liquid into chamber B. This would
provide room for the vapor to expand without allowing vapor to escape through the vent. As the
fuel tank cools, the vapor would condense. This would cause the level of the liquid in chamber A
to rise while the level of the liquid in chamber B would drop. Some pressurization may occur in
the fuel tank with this system, but it would be much less than for a sealed fuel tank due to the
expansion chamber. Any pressure or vacuum in the fuel system would be a function of the VCS
design and would be expected to be less than 0.5 psi. In addition, a pressure relief valve could
be added to the system to protect against any high pressure excursions.
In the initial testing of the VCS, the manufacturer has used water as the liquid barrier.
However, they stated that ethylene-glycol or even oil could be used which would be more stable
liquids and would resist freezing. Diurnal testing was performed on a 25 gallon fuel tank
equipped with a roughly 3 gallon VCS unit.40 Testing was performed in a mini-SHED over the
EPA 72-96°C diurnal cycle for two days. The tank was filled to 50 percent capacity with 9 RVP
certification gasoline. The total weight loss was 1.1 grams on the first day and 2.6 grams on the
second day. Using the higher of the two days, we get a diurnal emission rate of about 0.1
g/gal/day. The peak pressure during this testing was approximately 0.5 psi.
5.2 Running Loss Emissions
Running loss emissions are similar to diurnal emissions except that the fuel temperature
rise is due to heat from the engine or other heat producing components, such as hydraulic
systems, when the engine is running. This section summarizes the data and rationale supporting
the running loss emission standard for Small SI equipment presented in the Executive Summary.
5.2.1 Baseline Emissions
To investigate running loss emissions, we instrumented seven riding lawnmowers, three
walk-behind lawnmowers, two generators, and one pressure washer to measure the fuel
temperature during typical operation. Many of the temperature measurements were made by a
contractor.41 Of the riding mowers, two had fuel tanks in front near the engine, three had fuel
tanks in rear away from engine (but near the hydraulic system), and two were "zero-turn"
mowers that had pairs of side saddle tanks that were relatively close to the rear mounted engine.
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Draft Regulatory Impact Analysis
All of the riding mowers had plastic fuel tanks. One of the walk-behind mowers had a metal
tank directly mounted to the block while the others had plastic tanks near the top/side of the
engine. Both generators had plastic tanks mounted above the engine while the pressure washer
had a metal tank mounted above the engine. All of the equipment vented through the fuel caps.
The pressure washer had a metal fuel tank mounted above the engine. The equipment was
operated in the field until the fuel temperature stabilized. For lawnmowers, the fuel temperature
stabilized within 20 to 30 minutes while the larger equipment took up to an hour.
By measuring the increase in fuel temperature during operation, we were able to make a
simple determination of the running loss emissions vented from the fuel tank. Other potential
running loss emissions would be from the carburetor, due to permeation increases due to heating
the fuel, or vibration-induced leaks in the fuel system. However, we believed that the majority
of the running loss emissions would be due to breathing losses associated with heating the fuel.
Table 5.2-1 presents the results of the temperature testing.
We contracted with an independent testing laboratory to test fuel tanks from most of the
above pieces of equipment over the measured fuel temperature profiles.42 For three of the tests
on larger fuel tanks, we found that the measured emissions were inconsistent with theoretical
predictions. An investigation of the test data suggested that the test had been ended too soon to
see the full effect of the heat build. Repeat tests were performed with a longer sample time.43
From this data we get the running loss emissions due to the breathing losses associated with the
heating of the fuel tank. New tanks were purchased for this testing that had not been previously
exposed to fuel so permeation emissions would not be included in the emission measurements.
Table 5.2-1 also presents the test results for the above equipment.
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Feasibility of Evaporative Emission Control
Table 5.2-1: Fuel Temperature Measurements During Operation of
Small SI Equipment and Hydrocarbons Measured Over This Temperature Profile
Equipment Type
Riding mower
front tank near engine
Riding mower
rear tank away from engine
Zero-turn riding mower
2 saddle tanks near engine
Walk-behind mower (plastic)
Walk-behind mower (metal)
Generator set
Pressure washer
Fuel Capacity
[gallons]
1.7
1.1
6.5
3.0
2.5
6.5x2
1.4x2
0.34
0.25
0.22
8.5
7.0
1.8
Min. Temp
°C
19.5
15.7
24.3
26.6
27.0
20.5
21.9
23.3
28.7
28.7
20.6
25.8
19.0
Max. Temp
°C
30.3
28.4
33.2
28.4
35.0
23.9
29.7
33.0
46.7
59.7
25.8
50.0
50.6
HC [g/hr]
1.4
1.0
7.8
0.7
3.2
3.4
2.5
0.3
1.2
8.1
1.8
69.3
20.3
The California Air Resources Board performed running loss tests on several pieces of
Small SI equipment.44 This equipment included four lawnmowers (2 new and 2 old), one string
trimmer, two generators, two ATVs, and two forklifts. To measure running loss emissions, the
equipment were operated on California certification fuel in a SHED and the exhaust was routed
outside the SHED. Running loss emissions were determined by measuring the HC concentration
in the SHED. Therefore the measurements included all evaporative emissions during operation
including those from fuel heating, permeation, carburetor losses, and, for the two older
lawnmowers, liquid fuel leaks. Although the ATVs and forklifts are not considered to be small
offroad engines, these data can be used as surrogates for equipment that were not tested. Table
5.2-2 presents this data.
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Draft Regulatory Impact Analysis
Table 5.2-2: Results from ARE Running Loss Tests
Equipment Type
lawnmower
string trimmer
generator
ATV
forklift
Model Year*
2000
2001
1994
1989
1999
1995
2001
2001
2001
1995
1987
Running Loss [g/hr]
0.8
2.6
27.0
12.1
0.6
19.5
1.8
21.4
1.3
1.8
7.4
the 2000 and 2001 equipment were new at the time of testing
5.2.2 Control Technology
Running loss emissions can be controlled by sealing the fuel cap and routing vapors from
the fuel tank to the engine intake. In doing so, vapor generated heat from the engine will be
burned by the engine. It may be necessary to use a valve or limited flow orifice in the purge line
to prevent fuel from entering the line in the case of the equipment turning over and to limit the
vapor to the engine during operation. Depending on the configuration of the fuel system and
purge line, a one way valve in the fuel cap may be desired to prevent a vacuum in the fuel tank
during engine operation. We anticipate that a system like this would eliminate running loss
venting emissions. However, higher temperatures during operation would increase permeation
somewhat. In addition, the additional length of vapor line would increase permeation.
Considering these effects, we still believe that the system described here would result in more
than a 90 percent reduction in running loss emissions from Small SI equipment.
A secondary benefit of running loss control for Small SI equipment has to do with
diffusion emissions. As discussed above, venting a fuel tank through a hose (rather than through
an open orifice) greatly reduces diffusion. In the system discussed above, all venting losses
would occur through the vapor hose to the engine intake rather than through open vents in the
fuel cap. Therefore, the diffusion effect should be largely eliminated.
Another approach to reducing running loss emissions would be to insulate the fuel tank
or move it further from heat sources such as the engine or hydraulic system. With this approach,
the fuel cap vent would likely still be used, but diffusion could be controlled using a tortuous
vent path in the cap as described above.
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Feasibility of Evaporative Emission Control
For marine fuel tanks we are not considering running loss emissions. For portable fuel
tanks and installed fuel tanks on larger vessels, we would not expect there to be significant
heating of the fuel tanks during engine operation due to the distance from the engine and the
cooling effect of operating the vessel in water. For personal watercraft, the fuel tanks have a
sealed system with pressure relief that should help contain running loss emissions. For other
installed fuel tanks, we would expect the diurnal emission control system to capture about half of
any running losses as well.
5.3 Fuel Tank Permeation
The polymeric material (plastic) of which many gasoline fuel tanks manufactured
generally has a chemical composition much like that of gasoline. As a result, constant exposure
of gasoline to these surfaces allows the material to continually absorb fuel. Permeation is driven
by the difference in the chemical potentials of gasoline or gasoline vapor on either side of the
material. The outer surfaces of these materials are exposed to ambient air, so the gasoline
molecules permeate through these fuel-system components and are emitted directly into the air.
Permeation emissions continue at a nearly constant rate, regardless of how much the vehicle or
equipment is used. Because of these effects, permeation-related emissions can therefore add up
to a large fraction of the total emissions from nonroad equipment.
This section summarizes the data and rationale supporting the permeation emission
standard for Small SI and Marine SI fuel tanks presented in the Executive Summary.
5.3.1 Baseline Fuel Tank Technology and Emissions
Fuel tanks may be constructed in several ways. Portable marine fuel tanks and some
small, higher production-volume, installed marine fuel tanks are generally blow-molded using
high-density polyethylene (HDPE). Larger, installed marine fuel tanks are generally either
rotationally-molded using cross-link polyethylene (XLPE) or are constructed out of welded
aluminum. Some boat builders even construct the fuel tanks out of fiberglass as part of the
vessel construction. Fuel tanks on Small SI equipment may be injection molded, blow molded or
rotationally molded. Blow-molded and injection-molded tanks are primarily made of HDPE, but
nylon is used as well in some applications. Rotationally molded fuel tanks are generally made
out of XLPE.
Blow molding is widely used for the manufacture of Small SI, portable marine, and PWC
fuel tanks. Typically, blow molding is performed by creating a hollow tube, known as a parison,
by pushing high-density polyethylene (HDPE) through an extruder with a screw. The parison is
then pinched in a mold and inflated with an inert gas. In automotive applications, non-
permeable plastic fuel tanks are produced by blow molding a layer of ethylene vinyl alcohol
(EVOH) or nylon between two layers of polyethylene. This process is called coextrusion and
requires at least five layers: the barrier layer, adhesive layers on either side of the barrier layer,
and HDPE as the outside layers which make up most of the thickness of the fuel tank walls.
However, multi-layer construction requires additional extruder screws which significantly
increases the cost of the blow molding machine.
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Draft Regulatory Impact Analysis
Injection molding can be used with lower production volumes than blow molding due to
lower tooling costs. In this method, a low viscosity polymer is forced into a thin mold to create
each side of the fuel tank. The two sides are then welded together. In typical fuel tank
construction, the sides are welded together by using a hot plate for localized melting and then
pressing the sides together. The sides may also be connected using vibration or sonic welding.
Rotational molding has two advantages over blow molding, which is widely used for
forming automotive parts. First, the tooling cost is an order of magnitude lower than for blow-
molding. Therefore, for small production volumes such as seen for marine applications,
rotational molding is more cost-effective. Manufacturers of rotationally molded plastic fuel
tanks have commented that they could not produce their tanks with competitive pricing in any
other way. The second advantage of rotational molding is that larger parts can generally be
molded on rotational molding machines than on blow-molding machines. Plastic marine fuel
tanks can exceed 120 gallons.
Installed plastic marine fuel tanks are often produced in many shapes and sizes to fit the
needs of specific boat designs. These fuel tanks tanks are generally rotationally-molded out of
cross-link polyethylene. Cross-link polyethylene, which has a permeation rate comparable to
HDPE, is used in larger marine applications because of its ability to pass the U.S. Coast Guard
flame resistance requirements (33 CFR 183.590). Rotational-molding is also used in some Small
SI applications where there are low production volumes of unique fuel tanks. XLPE is used in
these fuel tanks as well because the fuel tank is often exposed and must be able to withstand
impacts such as flying debris.
5.3.1.1 Baseline permeation test data
5.3.1.1.1 Marine fuel tanks
To determine the baseline permeation emissions from marine fuel tanks, we have
collected permeation data on several plastic fuel tanks. Because gasoline does not permeate
through aluminum, we did not perform permeation testing on aluminum fuel tanks.
We tested ten plastic fuel tanks that were either intended for marine use or are of similar
construction. This permeation testing was performed at 29°C with gasoline. Prior to testing, the
fuel tanks were stored with gasoline in them for about 20 weeks to ensure stable permeation
rates. Table 5.3-1 presents the measured permeation rates for these fuel tanks in grams per
gallon of fuel tank capacity. Where the internal surface area was either easily determined or
supplied by the manufacturer, we also calculated the permeation rate in terms of grams per
square meter of inside surface area. The 31 gallon tank showed much lower permeation than the
other fuel tanks. This was likely due to the thickness of the walls in this tank. Even after
stabilization, permeation is a function of material thickness. According to Pick's Law, if the
wall thickness of a fuel tank were double, the permeation rate would be halved.45
5-30
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Feasibility of Evaporative Emission Control
Table 5.3-1: Permeation Rates for Plastic Marine Fuel Tanks Tested by EPA at 29°C
Tank Capacity
[gallons]
3.3
6.0
6.0
6.0
6.6
6.6
6.0
23
31
Permeation
[g/gal/day] [g/m2/day]
0.96
0.61
1.18
0.75
0.83
0.77
0.60
0.64
0.44
12.7
6.8
13.1
8.4
9.1
8.4
8.3
8.1
5.5
Construction
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
cross-link
cross-link
cross-link
Application
portable marine
portable marine
portable marine
portable marine
portable marine
portable marine
marine test tank
installed marine
installed marine
The Coast Guard tested three rotationally-molded, cross-link polyethylene marine fuel
tanks at 40°C (104°F) for 30 days.46 The results are presented in Table 5.3-2. Because
permeation emissions are a function of surface area and wall thickness, there was some variation
in the permeation rates from the three tanks on a g/gal/day basis. These results are not directly
comparable to the EPA testing because of the difference in test temperature. However, we can
adjust the permeation rates for temperature using Arrhenius' relationship47 combined with
empirical data collected on permeation rates for materials used in fuel tank constructions
(described below). These adjusted permeation rates are shown in Table 5.3-2 and are consistent
with the EPA test data.
Table 5.3-2: Permeation Rates for Cross-Link Marine Fuel Tanks at 40°C
Tank Capacity
[gallons]
12
18
18
Measured Permeation
Loss [g/gal/day]
1.48
1.39
1.12
Average Wall
Thickness [mm]
5.3
5.6
6.9
Adjusted to 29°C
[g/gal/day]
0.71
0.67
0.54
5.3.1.1.2 Small SI equipment fuel tanks
The California Air Resources Board (ARB) investigated permeation rates lawn & garden
equipment fuel tanks. The ARB data is compiled in several data reports on their web site and are
included in our docket.48'49'50'51'52 Table 5.3-3 presents a summary of this data which was
collected using the ARB Test Method 513.53 Where multiple tests were run on a given tank or
tank type, the average results are presented. Although the temperature in the ARB testing is
cycled from 18 - 41°C rather than held at a constant temperature, the average temperature is
29°C which is similar to the EPA testing. Therefore, the permeation results would likely be
similar if the data were collected at the average temperature of 29°C used in the EPA testing.
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Draft Regulatory Impact Analysis
Variation in permeation rates on a gram per square meter basis is likely due to differences in the
wall thicknesses. Note that surface area measurements were not available for all of the fuel
tanks. Smaller fuel tanks would be expected to have higher emissions on a gram per gallon basis
due to the increased surface area to volume ratio. However, lower permeation rates were
observed for the fuel tanks less than 1 quart, potentially due to relatively thicker walls or due to a
difference in material used for these applications.
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Feasibility of Evaporative Emission Control
Table 5.3-3: Permeation Rates for Plastic Lawn and
Garden Fuel Tanks Tested by ARE Over a 18-41°C Diurnal
Tank Capacity
[gallons]
0.06
0.08
0.09
0.09
0.10
0.12
0.15
0.16
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.29
0.38
0.38
0.38
0.38
0.50
0.50
0.55
0.74
1.4
1.7
1.8
3.9
5.0
5.0
5.0
7.5
Permeation Loss
[g/gal/day]
0.20
0.26
0.12
0.19
0.28
0.53
0.42
0.29
1.32
0.73
0.67
0.74
0.86
0.68
1.06
1.24
0.99
0.67
0.66
0.62
1.39
1.26
1.27
0.27
1.30
0.92
0.08
1.39
1.04
1.24
1.82
1.72
1.14
1.47
3.28
3.20
2.75
3.82
2.07
Permeation Loss
[g/m2/day]
5.39
6.67
—
5.88
—
9.01
7.32
4.79
11.56
10.65
9.75
10.75
12.54
9.91
9.24
10.84
8.68
9.80
9.65
9.07
12.17
11.03
15.00
—
10.66
9.18
—
12.69
8.53
—
—
7.81
—
6.19
4.84
—
—
8.80
2.86
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Draft Regulatory Impact Analysis
Some handheld equipment, primarily chainsaws, use structurally-integrated fuel tanks
where the tank is molded as part of the body of the equipment. In these applications the frames
(and tanks) are typically molded out of nylon for strength. We tested structurally-integrated fuel
tanks from four handheld equipment manufacturers at 29°C on both gasoline and s 10 percent
ethanol blend. The test results suggest that these fuel tanks are capable of meeting the proposed
standards using their current materials. In the cases where the permeation rates were higher than
the proposed standards, it was observed that the fuel cap seals had large exposed surface areas on
the O-rings, which were not made of low permeation materials. Emissions could likely be
reduced significantly from these tanks with improved seal designs. Table 5.3-4 presents the
results of this testing. Note that permeation emissions are 20 to 70 percent higher on E10 than
on gasoline for these fuel tanks.
Table 5.3-4: Permeation Rates for Nylon Handheld Fuel Tanks Tested by EPA at 29°C
Tank ID
Rl
R2
R3
Bl
B2
B3
B4
Wl
W2
W3
Gl
G2
G3
Application
clearing saw
(0.24 gallons)
hedge clipper
(0.05 gallons)
chainsaw
(0.06 gallons)
chainsaw
(0.06 gallons)
Material
nylon 6
nylon 6, 33% glass
nylon 6, 30% glass
nylon 6, 30% glass
Test Fuel
gasoline
E10
E10
gasoline
E10
E10
E10
gasoline
E10
E10
gasoline
E10
E10
Permeation Loss
[g/m2/day]
0.34
0.42
0.48
0.62
1.01
1.12
0.93
1.45
2.18
2.46
1.30
1.41
2.14
5.3.1.1.3 Portable fuel tanks
The California Air Resources Board (ARE) investigated permeation rates from portable
fuel containers. Although this testing was not on Small SI or marine fuel tanks, the fuel tanks
tested are of similar construction.54'55 The ARE data is compiled in several data reports on their
web site and is included in our docket. Table 5.3-5 presents a summary of this data which was
collected using the ARB Test Method 513.56 Due to the increasing surface to volume ratio with
decreasing fuel tank sizes, data presented in terms of grams per gallon for smaller tanks would be
expected to be higher for the same grams per surface area permeation rate. Although the
temperature in the ARB testing is cycled from 18 - 41°C rather than held at a constant
temperature, the results would likely be similar if the data were collected at the average
temperature of 29°C which is used in the EPA testing.
-------
Feasibility of Evaporative Emission Control
Table 5.3-5: Permeation Rates for HDPE Portable
Fuel Containers Tested by ARE Over a 18-41°C Diurnal
Tank Capacity
[gallons]
1.0
1.0
1.0
1.0
1.0
1.0
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
2.1
2.1
2.1
2.1
2.5
2.5
5.0
5.0
5.0
5.0
5.0
5.0
5.0
6.6
Permeation Loss
[g/gal/day]
1.63
1.63
1.51
0.80
0.75
0.75
0.50
0.49
0.51
0.52
0.51
0.51
1.51
1.52
1.88
1.95
1.91
1.78
1.46
1.09
0.89
0.62
0.99
1.39
1.46
1.41
1.47
1.09
5.3.1.2 Effect of temperature on permeation rate
It is well known that the rate of permeation is a function of temperature. For most
materials, permeability increases by about a factor of 2 for every 10°C increase in temperature.57
To determine this relationship for nonroad fuel tanks, we performed permeation testing on nine
HDPE Small SI fuel tanks at both 29°C and 36°C (85°F and 96°F).. This sample set included
both baseline and surface treated fuel tanks. On average (excluding the outlier), the temperature
effect was equivalent to nearly a factor of 2 increase in permeation per 10°C increase in
temperature. The one outlier likely resulted from measurement error due to the very low
permeation levels (0.5 grams lost over 2 weeks). Table 5.3-6 presents the test results.
5-35
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Draft Regulatory Impact Analysis
Table 5.3-6: Effect of Temperature on Permeation from HOPE Small SI Fuel Tanks
Tank
A
B
C
D
E
F
H
I
J
Treatment
untreated
sulfonated
fluorinated
29°C [g/m2/day]
11.5
11.4
11.2
2.48
2.73
2.24
0.56
0.62
0.22
36°C [g/m2/day]
17.1
16.6
17.0
4.10
3.98
3.42
0.75
0.68
0.31
Increase per 10°C
92%
86%
97%
127%
85%
100%
60%
17%
80%
Published data collected on HDPE samples at four temperatures58'59 suggest that the
permeation of gasoline through HDPE increases by about 80 percent for every 10°C increase in
temperature. This relationship is presented in Figure 5.3-1, and the numeric data can be found in
Appendix 5D.
Figure 5.3-1: Effect of Temperature on HDPE Permeation
ro
•o
CM
E
0)
150
100
50
0
0
10 20 30 40
degrees Celsius
50
60
70
Another study was performed on the permeation from complete automotive fuel
systems.60 These fuel systems, which included fuel tanks, hoses, and other components, were
tested at both 29°C and 40°C on three fuel types (gasoline, ethanol blend, and MTBE blend).
5-36
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Feasibility of Evaporative Emission Control
The effect of temperature on permeation did not appear to be significantly affected by fuel type.
Table 5.3-7 presents this data for ten automotive fuel systems tested on gasoline. This data
showed more than a factor of 2 increase in permeation per 10°C increase in temperature.
Table 5.3-7: Effect of Temperature on Permeation from Automotive Fuel Systems
Fuel System
2001 Toyota Tacoma
2000 Honda Odyssey
1999 Toy ota Corolla
1997 Chrysler Town & Country
1995 Ford Ranger
1993 Chevrolet Caprice Classic
1991 Honda Accord LX
1989 Ford Taurus GL
1985 Nissan Sentra
1978 Olds Cutlass Supreme
Fuel Tank
Metal
Plastic (enhanced
evap)
Metal
Plastic (enhanced
evap)
HOPE
Fluorinated HOPE
Metal
Metal
Metal
Metal
29°C
[mg/hr]
9
21
10
23
309
95
40
24
53
57
40°C
[mg/hr]
20
55
24
52
677
255
110
52
148
122
Increase
per 10°C
101%
136%
124%
110%
102%
143%
148%
100%
152%
99%
5.3.1.3 Units for reporting the permeation rate (g/gal/day vs. g/m2/day)
Much of the permeation data presented in this chapter is in units of grams of
hydrocarbons lost in a day divided by the capacity of the fuel tank (g/gal/day). For diurnal
emissions, these units are used because the vapor generation is a function of fuel tank volume.
For permeation emissions, we considered using these units because the capacity of the fuel tank
is generally readily available; either identified on the fuel tank or readily measured. However,
although volume is generally used to characterize fuel tank emission rates, permeation is actually
a function of surface area. Because the surface to volume ratio of a fuel tank changes with
capacity and geometry of the tank, two similar shaped tanks of different volumes or two different
shaped tanks of the same volume could have different g/gal/day permeation rates even if they
were made of the same material and used the same emission control technology. For this reason,
the final standards are based on units of grams per square meter of inside surface area
(g/m2/day).
This chapter presents permeation data for a large number of Small SI, marine, and other
fuel tanks. For many of these fuel tanks, we had information on both the volume and inside
surface area. Figure 5.3-2 presents the relationship between fuel tank volume in gallons and
inside surface area in square meters. As a fuel tank becomes smaller, its surface to volume ratio
increases. This relationship can be seen better in the chart to the right which presents only data
for fuel tanks less than 1 gallon. A hyperbolic curve is fit through the data in Figure 5.3-2 to
represent this relationship. This is seen better in the right-side chart which presents only smaller
tank sizes. In addition to fuel tank volume, the surface to volume ratio is affected by geometry
5-37
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Draft Regulatory Impact Analysis
of the fuel tank. A long flat-fuel tank would have a higher surface to volume than a cube or
spherical design. Larger plastic fuel tanks, used primarily in marine vessels, tend to have
somewhat high surface to volume ratios for this reason.
Figure 5.3-2: Relationship Between Tank Volume and Inside Surface Area
3.5 -i
0.0
10 20 30
volume [gallons]
40
0.20
0.00
0.0 0.5
volume [gallons]
1.0
5.3.1.4 Effect of fuel tank fill level on permeation
Permeation is driven by the chemical potential of the fuel or vapor in contact with the
plastic. In a fuel tank, the vapor is essentially at equilibrium with the fuel in a fuel tank.
Therefore, the permeation rate is the same through the surfaces in contact with saturated vapor as
it is through the surfaces in contact with the liquid fuel. Because the permeation rate of saturated
vapor and liquid fuel are the same, the fill level of the fuel tank during a permeation test does not
affect the measured results.
The fact that liquid fuel and saturated fuel vapor result
in the same permeation rates is supported by published
literature.61'62'63^64 In two of these studies, permeation was
measured for material samples using the cup method
illustrated in Figure 5.3-3. In these tests, no significant
difference was seen between the permeation rates for material
samples exposed to liquid fuel or to fuel vapor. To test for
permeation with fuel vapor, the cup was inverted so that the
fuel was on the bottom and the sample was taken off the top.
Table 5.3-8 presents the data from these two reports. In both
cases, the material being tested was a fluoroelastomer.
Figure 5.3-3: Cup Method
5-38
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Feasibility of Evaporative Emission Control
Table 5.3-8: Permeation Measured in Cup Method with Fuel Versus Vapor Fuel Exposure
Paper
SAE 200 1-0 1-1999
SAE 2000-01-1096
Fuel
CE10
CE10
CM15
Temperature
40°C
23 °C
40°C
23 °C
40°C
Liquid Fuel Exposure
30.5 g/m2/day
0.3 g/test
2.6 g/test
3.1 g/test
9.5 g/test
Fuel Vapor Exposure
29.5 g/m2/day
0.3 g/test
2.5 g/test
2.9 g/test
8.5 g/test
One commenter presented test data suggesting that fill level may affect permeation
emissions.65 They tested four HDPE jugs, two filled to 40 percent and two filled to 100 percent
with gasoline and saw a 15 percent difference in the average permeation results for the two fill
levels (1.3 g/gal/day for 40 percent fill and 1.5 g/gal/day for 100 percent fill). Although this
small measured difference was likely due to test variability, we performed our own testing to
study the effect of fill level. For this testing, we used two 6-gallon FfDPE portable marine fuel
tanks. The fuel tanks were soaked with gasoline for 12 weeks to ensure a stabilized permeation
rate. Each tank was tested at both 50 percent and 90 percent fill. No significant difference in
permeation rate was observed for either tank. Table 5.3-9 presents the results in terms of
g/gal/day at 29°C.
Table 5.3-9: Effect of Fuel Tank Fill Level on Permeation
for Two Portable Marine Fuel Tanks [g/gal/day]
Tank 1
Tank 2
50% fill
1.16
0.77
90% fill
1.21
0.78
Another study showed mixed results. Four automotive fuel systems (including fuel tank,
hose, and other components) were tested for permeation with the fuel tanks filled with Fuel C to
both 20 percent and 100 percent of capacity.66 Prior to the testing, the fuel tanks were soaked
with fuel at the specified fill levels until a stable permeation rate was achieved. It was not clear
what fraction of the permeation came from the fuel tanks compared to other fuel system
components or how the fuel level affected the exposure of the other components. In this study,
two of the fuel systems saw no significant change in permeation as a result of a change in fill
level. These two fuel system were on older vehicles, one with an untreated and one with a
fluorinated HDPE fuel tank. Two other fuel systems, using fuel tanks that meet automotive
enhanced evaporative emission requirements, showed significant reductions in fuel system
permeation (32 percent and 49 percent) when tested with the fuel tank filled to only 20 percent
capacity. The study presented no rationale for this effect; however, it should be noted that these
were very low permeation systems and measurement error would presumably be larger. These
data are presented in Table 5.3-10. In addition, it is possible that the change in fill level affected
whether or not there was fuel in the hoses. As discussed later in this chapter, the vapor
5-39
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Draft Regulatory Impact Analysis
concentration in fuel hoses may be significantly lower than saturated when exposed only to
vapor due to diffusion constraints.
Table 5.3-10: Effect of Fuel Tank Fill Level on Permeation
for Four Automotive Fuel Systems at 29°C [g/hour]
Rig 2
Rig 4
Rig 5
Rig 6
Description of Fuel Tank
enhanced evap system
enhanced evap system
HDPE fuel tank
fluorinated HDPE fuel tank
20% fill
0.013
0.021
0.350
0.095
80% fill
0.019
0.041
0.349
0.094
The California Air Resources Board also performed testing on three pairs of portable fuel
tanks.67 All of the fuel tanks were identical 1 gallon tanks made out of HDPE. Each pair was
filled to a different level with California certification fuel (30 percent, 50 percent and 70 percent
fill). The fuel tanks were then sealed and subjected to five days of the California diurnal test
(65-105T) and weight loss was measured daily. Over the five days of testing, the tanks with
lower fill levels actually saw significantly higher permeation than the other tanks. Looking at
the last day of testing, which represents some conditioning of the fuel tanks by the fuel resulting
in more stabilized permeation rates, the permeation rates are similar regardless of the fill level.
This data, which is presented in Table 5.3-11, suggests that the fuel vapor in the tanks permeated
at the same rate as (or higher than) the liquid fuel.
Table 5.3-11: Effect of Fuel Tank Fill Level on Permeation
for Three Pairs of Portable Fuel Tanks [g/day]
Tank
30a
3 Ob
50a
5 Ob
70a
70b
Fill Level
30%
50%
70%
5 -Day Permeation
.79
.57
.53
.03
.26
.08
Last Day Permeation
1.87
1.91
1.91
1.43
1.85
1.43
5.3.1.5 Effect of background concentration on permeation
As discussed above, permeation is driven by the difference in chemical potential between
the inside and outside of the tank. If the concentration of vapor outside the fuel tank were large
enough, it could reduce the permeation rate of fuel through the tank. One commenter presented
test data suggesting that, at very low concentrations of vapor in the boat around the fuel tank,
that the permeation rate would be significantly reduced.68 This test data was based on two three
hour tests on 5 gallon HDPE bottles at 35°C. They measured 0.57 g/hr with a background
5-40
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Feasibility of Evaporative Emission Control
concentration of 26 ppm and 0.36 g/hr with a background of 212 ppm. No repeat tests were run.
It is not clear why the above results were measured. Compared to the concentration of the fuel
vapor in the tank, this difference between 212 and 26 ppm is minuscule (about three orders of
magnitude difference from saturated vapor). It is more likely that this effect was due to test
variation.
To investigate this potential effect on permeation emissions further, we performed our
own testing. First, we measured the concentration of fuel vapor around the fuel tank on a
summer day in a runabout with the tank installed in the hull. This concentration was 1400 ppm.
We then tested two different fuel tanks for permeation with different background concentrations.
The background concentration was maintained by controlling the bleed of fresh air through the
test container or SHED. Each test ran for about two weeks and the permeation rates were
determined using the weight loss method. Prior to the testing, the tanks were soaked until a
stable permeation rate was achieved, then new fuel was added to the tank just prior to beginning
the test. The fuel tank was soaked until the fuel temperature stabilized at 29°C before the
beginning weight was measured. The results, which are presented in Table 5.3-12, showed no
significant difference in permeation as a function of background concentrations of hydrocarbon
vapor.
Table 5.3-12: Effect of Background Concentration on Permeation
Fuel Tank
6 gallon HOPE
23 gallon cross-link PE
Background [ppmC]
30
1500
30
150
1350
Permeation [g/gal/day]
0.77
0.78
0.64
0.67
0.66
5.3.2 Fuel Tank Permeation Reduction Technologies
There are several strategies that can be used to reduce permeation from plastic fuel tanks.
This section presents data collected on five permeation control strategies: sulfonation,
fluorination, non-continuous barrier platelets, coextruded continuous barrier, and alternative
materials.
5.3.2.1 Sulfonation
Sulfonation is a process where the surface of the fuel tank is treated to minimize
permeation. The sulfonation process uses sulfur trioxide is used to create the barrier by reacting
with the exposed polyethylene to form sulfonic acid groups on the surface. Current practices for
sulfonation are to place fuel tanks on a small assembly line and expose the inner surfaces to
sulfur trioxide, then rinse with a neutralizing agent. However, sulfonation can also be performed
off-line. Either of these processes can be used to reduce gasoline permeation by more than 90
5-41
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Draft Regulatory Impact Analysis
percent from new tanks.69
We tested several sulfonated marine fuel tanks at 29°C for permeation. This testing
included both HDPE blow-molded fuel tanks and cross-link polyethylene rotationally-molded
tanks. Both gasoline and alcohol fuel blends were investigated. In some cases, the fuel tanks
were exposed to durability testing as described in Section 5.6.2. The fuel tanks were stored with
fuel in them (soaked) for preconditioning, then they were drained and then filled with fresh fuel
prior to each permeation test. The purpose of the soak periods was to ensure that the fuel
permeation rate had stabilized and the purpose of the pressure cycles and slosh testing was to
evaluate the durability of the barrier treatment.
We also collected data from ARB and other sources on the effectiveness of sulfonation
for reducing permeation emissions from plastic fuel tanks. Most of this research has been
performed on blow-molded HDPE fuel tanks. As shown in these data, it is important that the
resin formulation be matched to the sulfonation process. The following discussions look at
sufonation results on HDPE and on cross-link polyethylene separately.
HDPE fuel tanks
We tested several HDPE fuel tanks that were sulfonated on the internal surfaces. These
included three 6-gallon and one 3.3 gallon portable marine fuel tanks and three all-terrain vehicle
(ATV) fuel tanks. These fuel tanks were sent to a sulfonater for barrier treatment. Multiple fuel
tanks were used so that they could be tested on certification gasoline , E10 (10 percent ethanol),
and M15 (15 percent methanol). The test results, presented in Table 5.3-13, showed more than a
90 percent reduction in permeation emissions from baseline. However, the two fuel tanks that
were subjected to slosh testing saw emission levels above the proposed standard. This may have
been a material compatibility issue as discussed below. The test results are consistent with
similar data collected by the California Air Resources Board.
5-42
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Feasibility of Evaporative Emission Control
Table 5.3-13: EPA Permeation Data on Sulfonated HDPE Fuel Tanks at 29°C
Treatment
Fuel
Soak Period
g/gal/day
g/m2/day
6 gallon portable marine fuel tanks
baseline
sulfonated
sulfonated
sulfonated
sulfonated
gasoline
gasoline
gasoline, sloshed
E10
M15
15 weeks
16 weeks
12 weeks
24 weeks
24 weeks
0.77
0.04
0.39
0.14
0.08
8.53
0.45
4.30
1.58
0.84
4 gallon ATV fuel tanks
sulfonated
sulfonated
sulfonated
gasoline
E10
M15
20 weeks
24 weeks
24 weeks
0.13
0.06
0.08
1.05
0.45
0.64
3.3 gallon portable fuel tank
baseline
sulfonated
sulfonated
E10
E10
E10, sloshed
14 weeks
14 weeks
38 weeks
0.96
0.06
0.16
12.7
0.83
2.09
We performed slosh testing on the 6 and 3.3 gallon portable marine fuel tanks with E10
fuel. This slosh testing included 1 million cycles consistent with the proposed durability test
procedure. After the slosh testing, the permeation rates were measured to be 2.0 and 4.3
g/m2/day for the 3.3 and 6 gallon fuel tanks, respectively. As discussed below, we believe that
the impact of the durability testing on the effectiveness of sulfonation can be minimized if the
sulfonation process and material properties are matched properly. However, this data supports
the need for the proposed durability testing requirements.
The California Air Resources Board (ARE) collected test data on permeation rates from
sulfonated portable fuel containers using California certification fuel.70 The results show that
sulfonation can be used to achieve significant reductions in permeation from plastic fuel
containers. This data was collected using a diurnal cycle from 18-41°C which is roughly
equivalent to steady-state permeation testing at 29°C. The average emission rate for the 32
sulfonated fuel tanks is 0.35 g/gal/day; however, there was a wide range in variation in the
effectiveness of the sulfonation process for these fuel tanks. Some of the data outliers were
actually higher than baseline emissions. This was likely due to leaks in the fuel tank which
would result in large emission increases due to pressure built up with temperature variation over
the diurnal cycle. Removing these five outliers, the average permeation rate is 0.17 g/gal/day
with a minimum of 0.01 g/gal/day and a maximum of 0.64 g/gal/day. This data suggests that
more than a 90 percent reduction in permeation from HDPE fuel tanks is possible through
sulfonation. This data is presented in Table 5.3-14.
5-43
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Draft Regulatory Impact Analysis
Plastic
Table 5.3-14: Permeation Rates for Sulfonated
Fuel Containers Tested by ARE Over a 18-41°C Diurnal
Tank Capacity
[gallons]
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
5
5
5
5
5
5
5
Permeation Loss
[g/gal/day]
0.05
0.05
0.05
0.06
0.06
0.06
0.08
0.12
0.14
1.23
1.47
1.87
0.02
0.02
0.48
0.54
1.21
0.03
0.08
0.32
0.38
0.42
0.52
0.64
0.80
0.01
0.04
0.05
0.06
0.11
0.13
0.15
Variation can occur in the effectiveness of this surface treatment if the sulfonation
process is not properly matched to the plastic and additives used in the fuel tank material. For
instance, if the sulfonater does not know what UV inhibitors or plasticizers are used, they cannot
maximize the effectiveness of their process. Earlier data collected by ARB showed consistently
high emissions from sulfonated fuel tanks; however, ARB and the treatment manufacturers agree
that this was due to inexperience with treating fuel tanks and that these issues have since been
5-44
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Feasibility of Evaporative Emission Control
largely resolved.71
ARB also investigated the effect of fuel slosh on the durability of sulfonated surfaces.
Three half-gallon fuel tanks used on Small SI equipment were sulfonated and tested for
permeation before and after being sloshed with fuel in them 1.2 million times.72'73 These fuel
tanks were blow-molded HDPE tanks used in a number of Small SI applications including
pressure washers, generators, snowblowers, and tillers. The results of this testing show that an
85 percent reduction in permeation was achieved on average even after the slosh testing was
performed. Table 5.3-15 presents these results which were recorded in units of g/m2/day. The
baseline level for Set #1 is an approximation based on testing of similar fuel tanks, while the
baseline level for Set #2 is based on testing of those tanks.
The sulfonater was not aware of the materials used in the fuel tanks sulfonated for the
slosh testing. After the tests were performed, the sulfonater was able to get some information on
the chemical make up of the fuel tanks and how it might affect the sulfonation process. For
example, the UV inhibitor used in some of the fuel tanks is known as HALS. HALS also has the
effect of reducing the effectiveness of the sulfonation process. Two other UV inhibitors, known
as carbon black and adsorber UV, are also used in similar fuel tank applications. These UV
inhibitors cost about the same as HALS, but have the benefit of not interfering with the
sulfonation process. The sulfonater claimed that if HALS were not used in the fuel tanks, a 97
percent reduction in permeation would have been seen.74 To confirm this, one manufacturer
tested a sulfonated tank similar to those in Set #2 except that carbon black, rather than HALS,
was used as the UV inhibitor. This fuel tank showed a permeation rate of 0.88 g/m2/day at
40°C75 which was less than half of what the CARB testing showed on their constant temperature
test at 40°C.76 A list of resins and additives that are compatible with the sulfonation process is
included in the docket.77'78
5-45
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Draft Regulatory Impact Analysis
Table 5.3-15: Permeation Rates for Sulfonated Fuel Tanks
with Slosh Testing by ARE Over a 18-41°C Diurnal
Technology
Configuration
Set #1 Approximate
Baseline
Set #1 Sulfonated
Set#l Sulfonated &
Sloshed
Set #2 Average Baseline
Set #2 Sulfonated
Set #2 Sulfonated &
Sloshed
Units
g/m2/day
g/m2/day
%
reduction
g/m2/day
%
reduction
g/m2/day
g/m2/day
%
reduction
g/m2/day
%
reduction
Tankl
10.4
0.73
93%
1.04
90%
12.1
1.57
87%
2.09
83%
Tank 2
10.4
0.82
92%
1.17
89%
12.1
1.67
86%
2.16
82%
Tank3
10.4
1.78
83%
2.49
76%
12.1
1.29
89%
1.70
86%
Average
10.4
1.11
89%
1.57
85%
12.1
1.51
88%
1.98
84%
About a year and a half after the California ARE tests on the Set #2 fuel tanks, we
performed permeation tests on these fuel tanks. During the intervening period, the fuel tanks
remained sealed with California certification fuel in them. We drained the fuel tanks and filled
them with fresh California certification fuel. We then measured the permeation rate at 29°C.
Because this is roughly the average temperature of the California variable temperature test,
similar permeation rates would be expected. The untreated fuel tanks showed slightly lower
permeation over the constant temperature test. This difference was likely due to the difference in
the temperature used for the testing. However, the Sulfonated fuel tanks showed an increase in
permeation. This increase in permeation appears to be the result of the 1.5 year additional fuel
soak. After this long soak, the average permeation reduction changed from 84 to 78 percent.
Table 5.3-13 presents this comparison.
5-46
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Feasibility of Evaporative Emission Control
Table 5.3-16: Permeation Rates [g/m2/day] for Sulfonated Fuel Tanks Tested by
ARE and EPA on CA Certification Gasoline with a 11A Year Fuel Soak Differential
Technology
Configuration
Baseline, CARB testing
Baseline, EPA testing
after 1.5 year additional
fuel soak
Sulfonated, CARB
testing
Sulfonated, EPA testing
after 1.5 year additional
fuel soak
Temperatu
re
18-4FC
29°C
% change
18-4FC
29°C
%
reduction
Tankl
12.1
11.5
-5%
2.09
2.48
78%
Tank 2
12.1
11.4
-6%
2.16
2.73
76%
Tank3
12.1
11.2
-7%
1.70
2.24
80%
Average
12.1
11.4
-6%
1.98
2.5
78%
After the above testing, we drained the fuel tanks and filled them with certification
gasoline splash-blended with 10 percent ethanol (E10). We then soaked the fuel tanks for 20
weeks to precondition them on this fuel. Following the preconditioning, we tested these fuel
tanks for permeation at 29°C (85°F). Table 5.3-17 presents these emission results compared to
the emission results for three baseline tanks (untreated) that were subject to the same
preconditioning. Percent reductions are presented based on the difference between the
sulfonated fuel tanks and the average results of the three untreated fuel tanks.
Table 5.3-17: Permeation Rates for Sulfonated Fuel Tanks on E10 Fuel at 29°C
Technology
Configuration
Baseline (untreated)
Sulfonated
Units
g/m2/day
g/m2/day
%
reduction
Tankl
13.9
3.91
72%
Tank 2
13.7
4.22
70%
Tank3
14.4
2.92
79%
Average
14.0
3.69
74%
An in-use durability testing program was also completed for sulfonated HDPE fuel tanks
and bottles.79 The fuel tank had a 25 gallon capacity and was removed from a station wagon that
had been in use in southern California for five years (35,000 miles). The fuel tank was made of
FIDPE with carbon black used as an additive. After five years, the sulfonation level measured on
the surface of the plastic fuel tank did not change. Tests before and after the aging both showed
a 92 percent reduction in gasoline permeation due to the sulfonation barrier compared to the
permeation rate of a new untreated tank. Testing was also done on 1 gallon bottles made of
FIDPE with 3 percent carbon black. These bottles were shown to retain over a 99 percent barrier
5-47
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Draft Regulatory Impact Analysis
after five years. This study also looked at other properties such as yield strength and mechanical
fatigue and saw no significant deterioration.
One study looked at the effect of alcohol in the fuel on permeation rates from sulfonated
fuel tanks.80 In this study, the fuel tanks were tested with both gasoline and various methanol
blends. No significant increase in permeation due to methanol in the fuel was observed.
XLPE fuel tanks
We tested eight sulfonated cross-link polyethylene (XLPE) fuel tanks for permeation
emissions. These tanks were produced by marine fuel tank manufacturers specifically for this
testing. The fuel tanks were then treated by a sulfonater. For the first four tanks tested, the fuel
tanks were molded using the resin formulation and processes currently used by the fuel tank
manufacturers. When the sulfonation was applied, we observed that the barrier was soft and
could be scraped off easily. When tested, the barrier on these fuel tanks was not as effective as
had been seen on HDPE fuel tanks.
Because the barrier could be scratched off, the sulfonater ascertained that the sulfonation
had poor surface penetration and the darkness of the barrier suggested heavy oxidation. For the
next batch of four test tanks, the sulfonater worked with the material supplier and roto-molder
and attempted to develop a formulation that may be more compatible with sulfonation. They
decided to use the same material, but bake it in the oven longer to remove more oxygen from the
surface of the fuel tank. Four bake times were used to produce the four 6-gallon test tanks: 11,
12, 14, and 16 minutes. It was observed that the sulfonation barrier could not easily be scratched
off these fuel tanks. We tested the four sulfonated on E10 (10 percent ethanol) using the same
procedures as for the HDPE tanks discussed above. The test results did not show a significant
improvement.
Another approach may be to mold an inner liner of HDPE inside a XLPE shell. These
materials readily bond with each other and sulfonation has been demonstrated for HDPE. This
construction, which is currently used in chemical storage applications, is performed in the oven
through the use of a "drop box" in the mold containing the HDPE. This drop-box is opened part
way through the oven cycle allowing for a HDPE layer to be molded on the inside of the fuel
tank.
5.3.2.2 Fluorination
Another barrier treatment process is known as fluorination. The fluorination process
causes a chemical reaction where exposed hydrogen atoms are replaced by larger fluorine atoms
which form a barrier on the surface of the fuel tank. In this process, fuel tanks are generally
processed post production by stacking them in a steel container. The container is then voided of
air and flooded with fluorine gas. By pulling a vacuum in the container, the fluorine gas is
forced into every crevice in the fuel tanks. As a result of this process, both the inside and outside
surfaces of the fuel tank would be treated. As an alternative, fuel tanks can be fluorinated on-
line by exposing the inside surface of the fuel tank to fluorine during the blow molding process.
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Feasibility of Evaporative Emission Control
However, this method may not prove as effective as off-line fluorination which treats the inside
and outside surfaces.
We tested several fluorinated marine fuel tanks at 29°C for permeation. This testing
included both HDPE blow-molded fuel tanks and cross-link polyethylene rotationally-molded
tanks. Both gasoline and alcohol fuel blends were investigated. In some cases, the fuel tanks
were exposed to durability testing as described in Section 5.6.2. The fuel tanks were stored with
fuel in them (soaked) for preconditioning, then they were drained and then filled with fresh fuel
prior to each permeation test. The purpose of the soak periods was to ensure that the fuel
permeation rate had stabilized and the purpose of the pressure cycles and slosh testing was to
evaluate the durability of the barrier treatment.
We also collected data from ARB and other sources on the effectiveness of fluorination
for reducing permeation emissions from plastic fuel tanks. Most of this research has been
performed on blow-molded HDPE fuel tanks. However, we believe that fluorination can also be
applied effectively for injection-molded HDPE tanks as well. The following discussion looks at
each material separately as well as rotationally-molded cross-link polyethylene.
Blow-molded HDPE fuel tanks
We tested one fluorinated HDPE fuel tank which we bought off the shelf and sent to a
fluorinater for barrier treatment. The fuel tank type used was a 6-gallon portable marine fuel
tank. The fuel tank was soaked for 20 weeks with certification gasoline prior to testing. We
measured a permeation rate of 0.05 g/gal/day (0.56 g/m2/day) which represents more than a 95
percent reduction from baseline. We then began soaking this fuel tank on E10, subjected it to
the proposed pressure and slosh testing, and retested the fuel tank. The post durability testing
result showed a permeation rate of 0.6 g/gal/day (6.8 g/m2/day). As discussed below, we believe
that the impact of the durability testing on the effectiveness of fluorination on can be minimized
if the fluorination process and material properties are matched properly. In addition, this fuel
tank was treated to a significantly lower level of fluorination than is now available. However,
this data supports the need for the proposed durability testing requirements.
The California Air Resources Board (ARB) collected test data on permeation rates from
fluorinated fuel containers using California certification fuel.81'82 The results show that
fluorination can be used to achieve significant reductions in permeation from plastic fuel
containers. This data was collected using a diurnal cycle from 18-41°C which is roughly
equivalent to steady-state permeation testing at 30°C. For the highest level of fluorination, the
average permeation rate was 0.04 g/gal/day which represents a 95 percent reduction from
baseline. Earlier data collected by ARB showed consistently high emissions from fluorinated
fuel tanks; however, ARB and the treatment manufacturers agree that this was due to
inexperience with treating fuel tanks and that these issues have since been largely resolved.83
The ARB data is presented in Table 5.3-18.
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Draft Regulatory Impact Analysis
Table 5.3-18: Permeation Rates for Fluorinated
Plastic Fuel Containers Tested by ARE Over a 18-41°C Diurnal
Barrier Treatment*
Level 4
(average =0.09 g/gal/day)
Level 5
(average =0.07 g/gal/day)
SPAL
(average =0.04 g/gal/day)
Tank Capacity
[gallons]
1
1
1
5
5
5
1
1
1
1
1
1
1
1
1
2.5
2.5
2.5
2.5
2.5
5
5
5
5
5
5
Permeation Loss
[g/gal/day]
0.05
0.05
0.06
0.11
0.11
0.15
0.03
0.04
0.05
0.05
0.07
0.08
0.11
0.11
0.12
0.04
0.04
0.05
0.07
0.07
0.05
0.10
0.11
0.04
0.04
0.04
* designations used in ARB report; shown in order of increasing treatment
All of the data on fluorinated fuel tanks presented above were based on fuel tanks
fluorinated by the same company. Available data from another company that fluorinates fuel
tanks shows a 98 percent reduction in gasoline permeation through a HDPE fuel tank due to
fluorination.84
ARB investigated the effect of fuel slosh on the durability of fluorinated surfaces. Two
sets of three fluorinated fuel tanks were tested for permeation before and after being sloshed with
fuel in them 1.2 million times.85'86 These fuel tanks were 0.5 gallon, blow-molded HDPE tanks
used in a number of Small SI applications including pressure washers, generators, snowblowers,
and tillers. The results of this testing show that an 80 percent reduction in permeation was
achieved on average even after the slosh testing was performed for Set #1. However, this data
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Feasibility of Evaporative Emission Control
also showed a 99 percent reduction for Set #2. This shows the value of matching the barrier
treatment process to the fuel tank material. Table 5.3-19 presents these results which were
recorded in units of g/m2/day. The baseline level for Set #1 is an approximation based on testing
of similar fuel tanks, while the baseline for Set #2 is based on testing of those tanks.
Table 5.3-19: Permeation Rates for Fluorinated Fuel Tanks
with Slosh Testing by ARE Over a 18-41°C Diurnal
Technology
Configuration
Set #1 Approximate
Baseline
Set #1 Fluorinated
Set #1 Fluorinated &
Sloshed
Set #2 Approximate
Baseline
Set #2 Fluorinated
Set #2 Fluorinated &
Sloshed
Units
g/m2/day
g/m2/day
%
reduction
g/m2/day
%
reduction
g/m2/day
g/m2/day
%
reduction
g/m2/day
%
reduction
Tankl
10.4
1.17
89%
2.38
77%
12.1
0.03
>99%
0.07
99%
Tank 2
10.4
1.58
85%
2.86
73%
12.1
0.00
>99%
0.11
99%
Tank3
10.4
0.47
96%
1.13
89%
12.1
0.00
>99%
0.05
>99%
Average
10.4
1.07
90%
2.12
80%
12.1
0.01
>99%
0.08
99%
About a year and a half after the California ARB tests on the Set #2 fuel tanks, we
performed permeation tests on these fuel tanks. During the intervening period, the fuel tanks
remained sealed with California certification fuel in them. We drained the fuel tanks and filled
them with fresh California certification fuel. We then measured the permeation rate at 29°C.
Because this is roughly the average temperature of the California variable temperature test,
similar permeation rates would be expected. The untreated fuel tanks showed slightly lower
permeation over the constant temperature test. This difference was likely due to the difference in
the temperature used for the testing. However, the fluorinated fuel tanks showed an increase in
permeation. This increase in permeation appears to be the result of the 1.5 year additional fuel
soak. Even after this long fuel soak, the fluorination achieves more than a 95 percent reduction
in permeation. Table 5.3-20 presents this comparison.
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Draft Regulatory Impact Analysis
Table 5.3-20: Permeation Rates [g/m2/day] for Fluorinated Fuel Tanks Tested by
ARE and EPA on CA Certification Gasoline with a 11A Year Fuel Soak Differential
Technology
Configuration
Baseline, CARB testing
Baseline, EPA testing
after 1.5 year additional
fuel soak
Fluorinated, CARB
testing
Fluorinated, EPA testing
after 1.5 year additional
fuel soak
Temperat
ure
18-41°C
29°C
% change
18-4FC
29°C
%
reduction
Tankl
12.1
11.5
-5%
0.07
0.56
95%
Tank 2
12.1
11.4
-6%
0.11
0.62
95%
Tank3
12.1
11.2
-7%
0.05
0.22
98%
Average
12.1
11.4
-6%
0.08
0.47
96%
After the above testing, we drained the fuel tanks and filled them with certification
gasoline splash-blended with 10 percent ethanol (E10). We then soaked the fuel tanks for 20
weeks to precondition them on this fuel. Following the preconditioning, we tested these fuel
tanks for permeation at 29°C (85°F). Table 5.3-21 presents these emission results compared to
the emission results for three baseline tanks (untreated) that were subject to the same
preconditioning. Percent reductions are presented based on the difference between the
fluorinated fuel tanks and the average results of the three untreated fuel tanks. The slight
increase in permeation on the E10 fuel was similar for the baseline and fluorinated fuel tanks and
still resulted in permeation rates well below the proposed standard.
Table 5.3-21: Permeation Rates for Fluorinated Fuel Tanks on E10 Fuel at 29°C
Technology
Configuration
Baseline (untreated)
Fluorinated
Units
g/m2/day
g/m2/day
%
reduction
Tankl
13.9
0.43
97%
Tank 2
13.7
0.62
96%
Tank3
14.4
0.62
96%
Average
14.0
0.56
96%
Another study also looked at the effect of alcohol in the fuel on permeation rates from
fluorinated fuel tanks.87 In this study, the fuel tanks were tested with both gasoline and various
methanol blends. No significant increase in permeation due to methanol in the fuel was
observed.
Under their rule for small offroad equipment, California may issue executive orders to
5-52
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Feasibility of Evaporative Emission Control
manufacturers with low emission products. As of August, 2006, ARB has issued 5 executive
orders for low permeation fuel tanks.88 Under these executive orders, three fluorination
approaches have been approved. The California fuel tank permeation standard is 1.5 g/m2/day
tested at 40°C on California certification fuel. Table 5.3-22 presents the test results for the fuel
tanks with ARB executive orders. Note that the reported emissions are the average of five test
samples.
Table 5.3-22: ARB Fuel Tank Executive Orders for Small Offroad Equipment
EO#
C-U-05-015
C-U-06-019
C-U-06-006
Test Fuel
Phase II
Phase II
Phase II
g/m2/day
1.10
0.30
0.38
One automobile manufacturer used fluorination to reduce permeation on HDPE fuel
tanks to meet the LEV I vehicle standards. This manufacturer used similar or more stringent
requirements for fuel soak, durability, and testing than finalized today. At 40°C, this
manufacturer stated that they measured 0.15-0.2 g/day for fluorinated tanks compared to over 10
g/day for untreated HDPE fuel tanks.89
Injection-molded HDPE fuel tanks
The issue has been raised by manufacturers that HDPE intended for injection-molding
has a somewhat different composition than HDPE used for blow-molding. To address this
concern, testing has been performed on fluorinated, injection-molded fuel tanks as well.90 These
fuel tanks were tested using California's TP-901 test procedures which preconditioning steps
including fuel soak, slosh testing, and pressure-vacuum cycling. California Phase II gasoline
was used for this testing.
Three similar fuel tanks were tested also over the proposed Federal test procedure.91
Under this testing, E10 fuel was used. Weight loss tests were performed before and after the
durability tests in 40 CFR 1501.515.92 These durability tests included slosh testing, pressure
vacuum cycling, and UV exposure. Results from this testing are presented in Table 5.3-23. The
permeation was significantly higher when tested on E10 fuel, especially when accounting for
differences in test temperature. In addition, permeation increased somewhat after the durability
testing. However, the measured permeation rates were well below the proposed fuel tank
permeation standard on E10 after the durability testing.
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Draft Regulatory Impact Analysis
Table 5.3-23: Permeation Rates for Fluorinated, Injection-Molded Fuel Tanks [g/mVday]
Test Procedure
California TP-901
Federal Baseline
After Durability Testing
Test
Temperature
40°C
28°C
28°C
Tankl
0.28
0.32
0.30
Tank 2
0.26
0.47
0.92
Tank 3
0.27
0.42
0.57
Average
0.27
0.41
0.60
XLPE fuel tanks
We tested several fluorinated cross-link polyethylene (XLPE) fuel tanks for permeation
emissions. The first tank was a 6 gallon test tank produced by a marine fuel tank manufacturer
specifically for this testing. The remaining fuel tanks were purchased on the open market. The
fuel tanks were then treated by a fluorinater. We tested the first tank on certification gasoline.
After a 20 week soak, we observed a permeation rate of 0.11 g/gal/day (1.52 g/m2/day), which
represented more than an 80 percent reduction in permeation.
The remainder of the fluorinated tanks were tested on E10 (10 percent ethanol) using the
same procedures as for the HDPE tanks discussed above. These fuel tanks were treated at a level
equivalent to what the fluorinater uses for automotive applications. All of the fuel tanks were
treated both on the inside and outside. The test results, presented in Table 5.3-24, showed
emission reductions of about 40 percent on average. Emission results from the sloshed fuel
tanks were not significantly different than from the tanks that were not sloshed.
Table 5.3-24: EPA Permeation Data on Fluorinated Cross-Link Fuel Tanks at 29°C on
E10
Fuel Tank
1
2
3
Capacity
12 gallons
12 gallons
12 gallons
Soak Period
29 weeks
29 weeks
29 weeks
g/gal/day
0.27
0.39
0.32
0.36
0.38
0.39
0.34
0.42
0.32
0.28
0.22
0.22
g/m2/day
4.1
5.9
4.9
5.4
5.8
5.7
5.0
6.2
4.6
3.4
2.6
2.8
slosh test?
no
no
no
no
no
yes
no
no
no
yes
no
no
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Feasibility of Evaporative Emission Control
5.3.2.3 Barrier Platelets
Another approach to creating a permeation barrier in a fuel tank is to blend a low
permeable resin in with the HDPE and extrude it with a single screw. The trade name typically
used for this permeation control strategy is Selar®. The low permeability resin, typically nylon
or EVOH, creates non-continuous platelets in the HDPE fuel tank which reduce permeation by
creating long, tortuous pathways that the hydrocarbon molecules must navigate to pass through
the fuel tank walls. Although the barrier is not continuous, this strategy can still achieve greater
than a 90 percent reduction in permeation of gasoline. EVOH has much higher permeation
resistance to alcohol than nylon; therefore, it would be the preferred material to use for meeting
our proposed standard which is based on testing with a 10 percent ethanol fuel.
We tested several portable gas cans and marine tanks molded with low permeation non-
continuous barrier platelets 29°C. Six of fuel tanks tested were constructed using nylon as the
barrier material. The remainder of the fuel tanks were constructed using ethylene vinyl alcohol
(EVOH) as the barrier material. The advantage of EVOH is that it has much better resistance to
alcohol than nylon. Five of the nylon based fuel tanks were tested on certification gasoline. The
sixth tank was tested on E10 (10 percent ethanol) to evaluate the effectiveness of this material
with alcohol blended fuel. The fuel tanks with the EVOH barrier were all tested on E10.
Testing was performed after the fuel tanks had been filled with fuel and stored at room
temperature. The purpose of the soak period was to ensure that the fuel permeation rate had
stabilized. Although 20 weeks was generally accepted as an acceptable period, we soaked the
tanks with gasoline for 22 weeks and the tanks with E10 for 37 weeks. The fuel tanks were
drained and then filled with fresh fuel prior to the permeation tests. Because the barrier platelets
are integrated in the tank wall material, it did not seem likely that pressure or slosh testing would
significantly affect the performance of this technology.
Table 5.3-25 presents the results of the permeation testing on the fuel tanks with barrier
platelets. These test results show more than an 80 percent reduction for the nylon barrier tested
on gasoline. However, the nylon barrier does not perform as well when a fuel with a 10 percent
ethanol blend is used. Testing on a pair of 2 gallon tanks with nylon barrier showed 80 percent
percent higher emissions when tested on E10 than on gasoline. We also tested fuel tanks that
used EVOH barrier platelets. EVOH has significantly better resistance to permeation on E10
fuel than nylon (see Appendix 5D for material properties). For the fuel tanks blended with 6
percent EVOH, we observed an average permeation rate of about 1.4 g/m2/day on E10 fuel
which meets our proposed permeation standard.
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Draft Regulatory Impact Analysis
Table 5.3-25: Permeation Rates for Plastic Fuel Containers
with Barrier Platelets Tested by EPA at 29°C
Percent
Selar®*
Tank Capacity
[gallons]
Test Fuel
Nylon barrier platelets
unknown* *
unknown* *
4%
4%
4%
4%
2
2
5
5.3
6.6
6.6
gasoline
E10
gasoline
gasoline
gasoline
gasoline
EVOH barrier platelets
2%
4%
4%
6%
6%
6.6
6.6
6.6
6.6
6.6
E10
E10
E10
E10
E10
Fuel Soak
[weeks]
40
40
22
22
22
22
37
37
37
37
37
g/gal/day
g/m2/day
0.54
0.99
0.35
0.11
0.15
0.14
3.7
6.8
4.1
1.2
1.6
1.5
0.23
0.14
0.15
0.08
0.09
3.0
1.9
2.0
1.4
1.4
*trade name for barrier platelet technology used in test program
** designed to meet California permeation requirement
Manufacturers raised the concern about whether or not a tank using barrier platelets
would have a stabilized permeation rate after 20 weeks. In other words, manufacturers were
concerned that this technology may pass the test, but have a much higher permeation rate in-use.
We tested one of the 4 percent and 6 percent EVOH tanks on E10 again after soaking for a total
of 104 weeks (2 years). The measured permeation rates were 2.0 and 1.4 g/m2/day for the 4
percent and 6 percent EVOH tanks, respectively, which represents no significant changes in
permeation from the 37 week tests. In contrast we measured the 4 percent nylon tanks again
after 61 weeks and measured a permeation rates of 2.8 and 2.7 g/m2/day which represented about
an 80-90 percent increase in permeation compared to the 22 week tests.
The California Air Resources Board (ARE) collected test data on permeation rates from
portable fuel containers molded with low permeation non-continuous barrier platelets using
California certification fuel. These fuel tanks all used nylon as the barrier resin. The results
show that this technology can be used to achieve significant reductions in permeation from
plastic fuel containers. This data was collected using a diurnal cycle from 18-41°C which is
roughly equivalent to steady-state permeation testing at 30°C. Because the data is reported in
g/gal/day, we only include the data on fuel tanks here that are compatible in size with marine
fuel tanks. This test data showed that more than a 90 percent reduction in permeation is
achievable through the use of nylon barrier platelets. However, all of this testing was performed
on California certification fuel which does not include ethanol.
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Feasibility of Evaporative Emission Control
Table 5.3-26: Permeation Rates for Plastic Fuel Containers
with Barrier Platelets Tested by ARB Over a 18-41°C Diurnal
Percent Selar®*
4%
(average =0.12 g/gal/day)
6%
(average =0.09 g/gal/day)
807
/O
(average =0.07 g/gal/day)
Tank Capacity
[gallons]
5
5
5
5
5
6
6
5
5
5
5
5
5
6
6
5
5
6
6
Permeation Loss
[g/gal/day]
0.08
0.09
0.13
0.16
0.17
0.08
0.10
0.07
0.07
0.07
0.08
0.12
0.17
0.06
0.07
0.08
0.10
0.05
0.06
*trade name for barrier platelet technology used in test program
Dupont, who manufacturers Selar®, has performed testing on HDPE with higher
blends of EVOH (known as Selar KB®). Table 5.3-27 presents permeation rates for HDPE and
three Selar KB® blends when tested at 60°C on xylene.93 Xylene is a component of gasoline and
gives a rough indication of the permeation rates on gasoline. This report also shows a reduction
of 99 percent on naptha and 98 percent on toluene for 8 percent Selar KB®.
Table 5.3-27: Xylene Permeation Results for Selar RB® at 60°C
Composition
100% HDPE
10%RB215/HDPE
10%RB300/HDPE
15%RB421/HDPE
Permeation, g mm/m2/day
285
0.4
3.5
0.8
% Reduction
99.9%
98.8%
99.7%
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Draft Regulatory Impact Analysis
5.3.2.4 Alternative Materials
Permeation can also be reduced from fuel tanks by constructing them out of a lower
permeation material than HDPE. Examples of alternative materials are metal, various grades of
plastic, and new fiberglass construction.
5.3.2.4.1 Metal
Gasoline does not permeation through metal. Therefore, the only permeation from a
metal fuel tank would be through rubber gaskets or O-rings that may be used to seal connections
on the fuel tank. Examples would be the gasket or O-ring in a fuel cap or a bolted-on component
such as a sender unit for a marine tank. Presumably, the exposed surface area of the gaskets
would be small enough that a metal fuel tank would be well below our proposed permeation
standard. One issue with metal fuel tanks, however, is fuel leakage due to corrosion. A study
sponsored by the Coast Guard in 1994 showed that aluminum (and even stainless steel) fuel
tanks are prone to failure, both in salt water and fresh water applications., due to corrosion.94
Fuel leakages would not only be an environmental issue, but could be a safety issue as well.
Aluminum fuel tank manufacturers have stated that corroding fuel tanks are typically due to
improper installation.
5.3.2.4.2 A Iternative Plastics
There are grades of plastics other than HDPE that could be molded into fuel tanks. One
material that has been considered by manufacturers is nylon; however, although nylon has
excellent permeation resistance on gasoline, it has poor chemical resistance to alcohol-blended
fuels. As shown in Appendix 5D, nylon could be used to achieve more than a 95 percent percent
reduction in permeation compared to HDPE for gasoline. However, for a 10 percent ethanol
blend, this reduction would significantly less depending on the grade of nylon. For a 15 percent
methanol blend, the permeation would actually be several times higher through nylon than
HDPE.
Some handheld equipment, primarily chainsaws, use structurally-integrated fuel tanks
where the tank is molded as part of the body of the equipment. In these applications, the frames
(and tanks) are typically molded out of nylon for strength. We tested structurally-integrated fuel
tanks from four handheld equipment manufacturers at 29°C on both gasoline and a 10 percent
ethanol blend. The test results suggest that permeation emissions are 20 to 70 percent higher on
E10 than on gasoline for these fuel tanks. Note these fuel tanks are capable of meeting the
proposed standards using their current materials. In the cases where the permeation rates were
higher than these standards, it was observed that the fuel cap seals had large exposed surface
areas on the O-rings, which were not made of low permeation materials. Emissions could likely
be reduced significantly from these tanks with improved seal designs. Table 5.3-28 presents the
results of this testing.
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Feasibility of Evaporative Emission Control
Table 5.3-28: Permeation Rates for Nylon Handheld Fuel Tanks Tested by EPA at 29°C
Tank ID
Rl
R2
R3
Bl
B2
B3
B4
Wl
W2
W3
Gl
G2
G3
Application
clearing saw
hedge clipper
chainsaw
chainsaw
Material
nylon 6
nylon 6, 33% glass
nylon 6, 30% glass
nylon 6, 30% glass
Test Fuel
gasoline
E10
E10
gasoline
E10
E10
E10
gasoline
E10
E10
gasoline
E10
E10
Permeation Loss
[g/m2/day]
0.34
0.42
0.48
0.62
1.01
1.12
0.93
1.45
2.18
2.46
1.30
1.41
2.14
Other materials which have excellent permeation resistance even with alcohol-blended
fuels are acetal copolymers and thermoplastic polyesters. These polymers can be used to form
fuel tanks in the blow-molding, rotational-molding, and injection-molding processes. An
example of an acetal copolymer is known as Celcon® which has excellent chemical resistance to
fuel and has been shown to be durable based on exposure to automotive fuels for 5000 hours at
high temperatures.95 As shown in Appendix 5D, Celcon would result in more than a 99 percent
reduction in permeation compared to HDPE for gasoline. On a 10 percent ethanol blend, the use
of Celcon would result in more than a 95 percent reduction in permeation. Two thermoplastic
polyesters, known as Celanex® and Vandar®, are also being considered for fuel tank construction
and are being evaluated for permeation resistance by the manufacturer. Celcon has a more
crystalline structure than Vandar resulting in lower permeation but less impact resistance.
We tested a 1-liter blow-molded Vandar fuel tank and three rotationally-molded 3-liter
fuel tanks made of impact toughened Celcon for permeation at 29°C on E10 fuel. Prior to the
permeation testing, the fuel containers were soaked in E10 for more than 20 weeks. These test
results are included in Table 5.3-29 below. For the Celcon tank tests, higher emissions were
observed in the second week than the first week. This behavior was seen in repeat tests and was
likely due to deterioration of the epoxy seal used in this testing. Therefore, the actual emission
rates of the material are likely lower than presented below. More detailed data on this testing is
available in the docket.96
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Draft Regulatory Impact Analysis
Table 5.3-29: Permeation Results Acetal Copolymer Fuel Tanks at 29°C on E10
Material Name
Vandar VI
Impact CIO
Resistant
Cll
Celcon C13
Material Type
thermoplastic polyester
modified
acetal copolymer
g/gal/day
1.7
0.13
0.09
0.10
g/m2/day
5.6
0.75
0.53
0.59
Fuel tank manufacturers have expressed some concern that the acetal copolymer is not as
tough as cross-link polyethylene. Thermoplastic polyesters have better impact resistance, but
higher permeation. The impact toughened fuel tanks mentioned above were in response to these
concerns. Also, the rotational molding process must be better controlled to use these materials in
comparison to XLPE. The temperature profile must be tightly controlled to uses Celcon, or
formaldehyde gases may form. The moisture level of Vandar must be kept low prior to molding.
Acetal copolymers are also used today to produce many fuel resistant automotive
components such as low permeation fuel caps. This construction has been used for many years
in automotive applications and now acetal copolymers are being used to manufacture low
permeation fuel caps for nonroad equipment as well.
Another low permeation thermoplastic that can be used in the manufacture of fuel tanks
is a polyester/polycarbonate alloy. One example is marketed under the trade name of Xenoy
6620. This engineered plastic is impact modified and is intended for the injection molding
process. The polyester provides good chemical resistance and the polycarbonate provides the
impact resistance. Permeation testing was performed on a fuel tank made of Xenoy 6620
following the California test procedures. At 40°C on California Phase II CERT fuel, the
measured permeation rate was 0.26 g/m2/day.97 The manufacturer of this material also has a
version that is modified slightly so that it can be used in the blow-molding process.
5.3.2.4.3 Low Permeation Fiberglass
One manufacturer has developed a low permeation fiberglass fuel tank construction.98
The composite tanks are fabricated using a glass fiber reinforced closed cell urethane composite
sheet as substrate and assembled with structural urethane adhesive as a fastening medium. These
fuel tanks may be hand constructed, or for larger volume production, they may be molded at
lower cost. Once fully assembled with necessary fuel fittings the tank is coated with fiberglass
reinforced resin, sufficient for H-24 ABYC (American Boat and Yacht Council) and 33 CFR
183.510 standards for fuel systems mechanical strength requirements. A final gel coat finish may
was applied for aesthetics.
Permeation control is achieved by incorporating fillers into a resin system and coating the
assembled tank interior and exterior. This filler is made up of nanocomposites (very small
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Feasibility of Evaporative Emission Control
particles of treated volcanic ash)4 which are dispersed into a carrier matrix. This construction
creates a tortuous pathway for hydrocarbon migration through the walls of the fuel tank. We
tested a 14 gallon fuel tank provided by this manufacturer and measured a permeation rate of
0.97 g/m2/day on E10 fuel at 29°C. Other advantages of this technology are improved strength
and flame resistance compared to plastic fuel tanks.
5.3.2.5 Multi-Layer Construction
Fuel tanks may also be constructed out of multiple layers of materials. In this way the
low cost and structural advantages of traditional materials can be utilized in conjunction with
higher grade materials which can provide effective permeation resistance. Today, fuel tanks are
made in many ways including higher volume blow-molding, lower volume injection molding,
and very low volume rotational-molding. The discussion below presents data on several multi-
layer fuel constructions.
5.3.2.5.1 Blow-Molded Coextruded Barrier
Coextruded barrier technology has been long established for blow-molded automotive
fuel tanks. Data from one automobile manufacturer showed permeation rates of 0.01-0.03 g/day
for coextruded fuel tanks at 40°C on EPA certification fuel. They are using this technology to
meet LEV II vehicle standards. For comparison, this manufacturer reported permeation rates of
more than 10 g/day for standard HDPE fuel tanks."
Another study looks at the permeation rates, using ARB test procedures, through multi-
layer fuel tanks.100 The fuel tanks in this study were 6 layer coextruded plastic tanks with EVOH
as the barrier layer (3 percent of wall thickness). The outer layers were HDPE and two adhesive
layers were needed to bond the EVOH to the polyethylene. The sixth layer was made of
recycled polyethylene. The two test fuels were a 10 percent ethanol blend (CE10) and a 15
percent methanol blend (CM15). See Table 5.3-30.
Table 5.3-30: Permeation Results for a Coextruded Fuel Tank Over a 18-41°C Diurnal
Composition
100% HDPE (approximate)
3% EVOH, 10% ethanol (CE10)
3% EVOH, 15% methanol (CM 15)
Permeation, g/day
6-8
0.2
0.3
% Reduction
97%
96%
The California Air Resources Board tested two sets of three 5-gallon portable fuel
containers.101 Each set was manufactured by a different company, but all of the fuel tanks were
blow-molded with a coextruded barrier layer. Testing was performed over the California 18-
41 °C temperature cycle with California Phase II gasoline. Testing was performed with and
4 Chemically modified montmorillonite for nanocomposite formulation
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Draft Regulatory Impact Analysis
without the spouts removed. The test data presented in Table 5.3-31 was after 174 days of fuel
soak with the spouts removed and the openings welded shut. California reported the test results
in grams per gallon. Table 5.3-31 also presents approximate g/m2/day values based on the
relationship between tank capacity and inside surface area used in the NONROAD2005
emissions model.
Table 5.3-31: ARB Permeation Results for a Coextruded Portable Fuel Tanks
Fuel Tank
Bl
B2
B3
Average
Ml
M2
M3
Average
Permeation, g/gal/day
0.01
0.01
0.01
0.01
0.01
0.02
0.02
0.02
Approximate Rate
0.09
0.11
0.11
0.10
0.14
0.21
0.18
0.17
in g/m2/day
Another approach has recently been developed in which a multi-layer fuel tank can be
blow-molded with only two layers.102 In this construction, a barrier layer of a polyarylamide
known as Ixef MXD6 is used on the inside of a HDPE fuel tank. Ixef has permeation properties
similar to EVOH. Test results showed a permeation rate of 0.8 g-mm/m2/day at 60°C on CE10
for a test film of Ixef. Unlike EVOH, Ixef can be exposed directly to the fuel which removes the
need for an inner layer of HDPE. In addition, a tie material can be blended into the HDPE which
will allow the polyarylamide to bond directly to the HDPE rather than using an adhesive layer.
5.3.2.5.2 Rotational Molded Dual-layer Construction
As discussed above, an inner layer can be molded into the inside of a rotationally molded
fuel tank through the use of a drop-box that opens after the XLPE tank begins to form. Through
this method, a XLPE fuel tank could be molded with a low permeation inner barrier. With this
construction, it may be possible to reduce the amount of XLPE used depending on the structural
characteristics of the inner liner material. For instance, acetal copolymer can be rotationally
molded and could be used as the inner liner. This way, the permeation characteristics of an
acetal copolymer could be achieved through an inner liner while still retaining the toughness of
XLPE . One issue would be that acetal copolymers do not readily adhere to XLPE. Therefore
fitting designs would need to account for this.
Another material that could be used in a multi-layer approach is nylon which comes in
many grades. Typical nylon grades used in Small SI fuel tank constructions may not perform
well in marine applications because of the hygroscopic nature of these nylons. In other words,
typical nylon adsorbs water which can make it brittle. In addition, E10 fuel permeates through
nylon much more readily than gasoline.
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Feasibility of Evaporative Emission Control
One manufacturer is working with a nylon known as Rilsan® polyamide 11 (PA 11) in
constructing low permeation multi-layer rotational-molded fuel tanks.103 Rilsan® polyamide 11
has two advantages to traditional nylons in that it is not hygroscopic and it is more resistive to
alcohol fuels. One manufacturer has manufactured fuel tanks using the PA11 as an inner liner in
a polyethylene shell. The manufacturer using this approach reports a permeation rate of about 3
g-mm/m2/day on fuel CE10 at 28°C compared to about 30 g-mm/m2/day for XLPE. In addition,
the nylon used in multi-layer constructions is formulated with a polyethylene graft that causes it
to adhere well to XLPE. This prevents the layers from separating in use.
We tested two 10 gallon multi-layer rotational molded fuel tanks at 29°C with E10 fuel
after a 35 week soak with two fuel changes during that period.104 One of the tanks was molded
with an outer shell of medium-density polyethylene while the other was molded with an outer
shell of cross-link polyethylene. The long soak period was due to test equipment problems and
the fuel was changed with each test attempt. However, it presents valuable data on the longer
term effectiveness of this technology. This test data is presented in Table 5.3-31. The
manufacturer reported that this tank design passed testing on the Coast Guard burn, pressure,
shock, and impulse test requirements.105'106'107'108 In addition, a tank of this construction was
tested and passed the tank durability tests for snowmobiles specified in SAE J288.109 These tests
include cold (-40°C) and hot temperature (60°C) immersion and drop tests.
Typically, multi-layer rotational-molded fuel tanks are constructed with the use of a drop
box which adds the inner-layer material into the mold after the first material sets. Other
approaches are to use a meltable bag containing the inner-layer material or even to pull the mold
from the oven to add the inner-layer material. However, one manufacturer, that participated in
the SBREFA process, has stated that they have developed a method to mold the inner liner
without the use of a drop box or other approach that lengthens molding cycle time. This fuel
tank manufacturer is selling fuel tanks using this construction for use in Small SI equipment and
is selling mono-layer XLPE rotational-molded tanks for use in boats.
Table 5.3-31: Permeation Results PA 11/PE Fuel Tanks at 29°C on E10
Tank
1
2
Outer Shell
MDPE
XLPE
g/gal/day
0.05
0.06
g/m2/day
0.71
0.79
Under their rule for small offroad equipment, California may issue executive orders to
manufacturers with low emission products. As of August, 2006, ARE has issued 5 executive
orders for low permeation fuel tanks.110 Under these executive orders, two basic multi-layer
rotomolded (XLPE and nylon) approaches have been approved. The California fuel tank
permeation standard is 1.5 g/m2/day tested at 40°C on California certification fuel. However,
most of the testing was performed on fuel CE10 which is a significantly more aggressive fuel for
permeation. Table 5.3-32 presents the test results for rotational-molded fuel tanks with ARE
executive orders. Note that the reported emissions are the average of 3-5 test samples.
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Table 5.3-32: ARE Fuel Tank Executive Orders for Small Offroad Equipment
EO#
C-U-05-005
C-U-06-014
Test Fuel
CE10
Phase II
CE10
CE10
CE10
g/m2/day
0.81
0.18
0.10
0.00
0.09
There is another approach to dual-layer rotomolded fuel tanks under development that
uses a "single shot" approach to molding.111 In this method a material known as polybutylene
terephthalate cyclic oligimor (CBT) is combined with the XLPE in the mold. Because of the
different melt rates and viscosities of the two materials, during the mold process, the CBT®
polymerizes into a thermoplastic known as polybutylene terephthalate (PBT) to form a barrier
layer on the inside of the fuel tank. Adhesion between the PBT and XLPE comes from
mechanical bonding between the two layers. This material can be used without lengthening the
cycle time for rotational molding, and it does not require forced cooling.112 Initial testing shows
a permeation rate of <1 g/m2/day when tested with fuel CE10 at 40°C for a sample with a 3.9 mm
total wall thickness.113 This wall thickness for this testing was composed of 0.9mm CBT and
3.0mm XLPE. PBT itself has a permeation rate on CE10 at 40°C of less than 0.05 g-mm/m2/day.
5.3.2.5.3 Injection-Molded Dual-Layer Construction
To add a barrier layer in the injection molding process, a thin sheet of the barrier material
may be placed inside the mold prior to injection of the poleythylene. The polyethylene, which
generally has a much lower melting point than the barrier material, bonds with the barrier
material to create a shell with an inner liner.
5.3.2.5.4 ThermoformedMulti-Layer Construction
As an alternative, multiple layers can be created through thermoforming.114 In this
process, sheet material is heated then drawn into two vacuum dies. The two halves are then
fused while the plastic is still molten to form the fuel tank. Before the halves are fused together,
it is possible to add components inside of the fuel tank. Low permeation fuel tanks can be
constructed using this process by using multi-layer sheet material. This multi-layer sheet can be
extruded using similar materials to multi-layer blow-molded fuel tank designs. A typical barrier
construction would include a thin EVOH barrier, adhesion layers on both sides, a layer of HDPE
regrind, and HDPE layers on the outside surfaces.
This process has low capital costs compared to blow-molding and should be cost
competitive with injection molding and rotational-molding. Manufacturers have indicated that
this construction could be coated with an intumescent material which would help it pass the
Coast Guard fire test. This coating could be applied directly to the multi-layer plastic sheets
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Feasibility of Evaporative Emission Control
while they are still hot after extrusion. Once the plastic cools, it could be applied using flame
ionization or electric arcing to increase the surface are of the plastic for adhesion.
EPA tested two, 5.6 gallon, thermoformed fuel tanks for permeation. These fuel tanks
were constructed as described above with a thin EVOH barrier and were soaked with E10 for 27
weeks prior to testing. Due to test variability, testing was repeated at 35 and 44 weeks (fresh
fuel was added prior to each weight loss test). From day to day, a constant weight loss was not
always observed, and weight gains were occasionally seen. This variability in measured weight
loss was likely due to the very low permeation rates combined with the effect of atmospheric
conditions on measured weight. The highest variations in weight loss were observed when
storms passed through suggesting that the changes in barometric pressure and relative humidity
were affecting the buoyancy of the fuel tanks (discussed in more detail in Section 5.6.2.3). In
the third round of testing (after 44 weeks), barometric pressure and humidity were measured and
deemed to be relatively stable. In addition, a smaller tank with sand in it (rather than fuel) was
measured simultaneously as a control to give some indication of the buoyancy effect. A small
weight loss was measured for the control tank, suggesting that the measured test results may
slightly overstate the permeation for the thermoformed fuel tanks. Table 5.3-33 presents the test
results for each of the three tests.
Table 5.3-33: Permeation Results Multilayer Thermoformed Fuel Tanks at 29°C on E10
Soak (weeks)
27
35
44
Average
Tank
#16
#21
#16
#21
#16
#21
#16
#21
g/gal/day
0.01
0.01
0.01
0.01
0.01
0.00
0.01
0.01
g/m2/day
0.15
0.05
0.07
0.09
0.11
0.04
0.11
0.06
5.3.2.5.5 Epoxy Barrier Coating
Another approach that has shown promising results is to coat a plastic fuel tank with a
low permeation epoxy barrier coating. Early attempts at coating a plastic fuel tank resulted in
coatings that eventually wear off due to the difficulty of bonding some materials to HDPE and
XLPE. However, because fluorination increases the surface energy of the plastic, a low level of
fluorination can be used to make it possible to apply an epoxy coating, even to XLPE. Because
this approach is applied to the fuel tank post-molding, it can be used for any plastic fuel tank,
regardless of the production molding method.
We performed permeation testing on six 12 gallon rotationally-molded XLPE fuel tanks
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Draft Regulatory Impact Analysis
with a thin, low-permeation epoxy coating. This coating was a two-part epoxy that was sprayed
onto the tank and thermally cured in 45 minutes. Prior to the permeation measurements, the fuel
tanks were soaked with E10 fuel at about 25°C for 15 weeks. The tanks were then drained and
fresh E10 was added prior to the 29°C constant temperature permeation test. Inspection of the
externally coated fuel tanks showed that the epoxy was unevenly applied and that some bare
spots existed. This was reflected in the unsatisfactory permeation results. A more careful
coating would be expected to result in similar results as the internal coatings. One of the
externally coated fuel tanks was over-coated with a 1-part epoxy that was cured with a 45 second
UV exposure. This tank was soaked for an additional 6 weeks prior to retesting. These test
results, which are presented in Table 5.3-34, show that this technology can be used to reduce
permeation emissions by more than 90 percent.
Table 5.3-34: EPA Permeation Data on Epoxy Coated XLPE Fuel Tanks at 29°C on E10
Fuel Tank Set
1
2
3
Coating
Inside
Thermocured
Outside
Thermocured*
Outside
UV cured
Soak Period
15 weeks
15 weeks
additional
6 weeks
g/gal/day
0.04
0.001
0.07
0.13
0.23
0.23
0.03
g/m2/day
0.6
0.02
1.0
1.9
3.3
3.3
0.4
slosh test?
no
no
yes
no
no
yes
no
* inspection showed uneven application of the coating which affected permeation results
Since the above testing was performed, the fluorinater and the epoxy manufacturer who
developed this approach have performed more testing on their UV cured, 1-part epoxy. The
testing was performed on epoxy coated HDPE bottles and 2 gallon fuel tanks using the
California APvB test procedure of 40°C with California certification fuel.115 At 29°C, we would
expect the permeation rate to be about half of these levels due to the relationship between
permeation and temperature discussed above in Section 5.3.1.2. The results for this testing were
reported to be 0.3 g/m2/day on average for both the bottles and tanks on gasoline. The bottles
had a permeation rate of 0.5 g/m2/day on gasohol (ethanol blend). This technology resulted in
better than 95 percent reductions in permeation. Table 5.3-35 presents the test results after a 9
week fuel soak at 40°C.
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Feasibility of Evaporative Emission Control
Table 5.3-35: Permeation Data: Epoxy Coated HOPE Fuel Tanks at 40°C on CA Cert Fuel
Fuel Tank
1
2
3
4
g/gal/day
0.04
0.02
0.02
0.08
g/m2/day
0.25
0.09
0.11
0.49
Roto-molders of marine fuel tanks generally use cross-link polyethylene. The advantage
of XLPE is that its cross-link structure causes it to behave like thermoset which helps the fuel
tanks pass the Coast Guard fire test (33 CFR 183.590) by holding their shape longer under
exposure to fire. If a flame retardant were included in the epoxy coating, a less expensive
material, such as FfDPE could be used to make fuel tanks that are subject to the flame test
requirement. The manufacturers who have developed the above approach for permeation have
developed an additive that provides an intumescent coating to allow the fuel tanks to be
produced at a lower cost. Testing on the Coast Guard burn test showed that an FfDPE fuel tank
would fail around after being exposed to a flame for about 1.5 minutes (the standard is 2.5
minutes). With the intumescent coating, the fuel tank passed the flame test and survived more
than 5 minutes.116
5.4 Fuel/Vapor Hose Permeation
The polymeric materials (plastic or rubber) used in the construction of gasoline fuel and
vapor hoses generally have chemical compositions much like that of gasoline. As a result,
constant exposure of gasoline to these surfaces allows the material to continually absorb fuel.
Permeation is driven by the difference in the chemical potentials of gasoline or gasoline vapor on
either side of the material. The outer surfaces of these materials are exposed to ambient air, so
the gasoline molecules permeate through these fuel-system components and are emitted directly
into the air. Permeation emissions continue at a nearly constant rate, regardless of how much the
vehicle or equipment is used. Because of these effects, permeation-related emissions can
therefore add up to a large fraction of the total evaporative emissions.
This section summarizes the data and rationale supporting the permeation emission
standard for fuel lines presented in the Executive Summary.
5.4.1 Baseline Hose Technology and Emissions
5.4.1.1 Marine Fuel Hose Subject to 33 CFR part 183
The majority of marine fuel hoses are constructed primarily of nitrile rubber with a
chloroprene cover for abrasion and flame resistance. Hoses are designed to meet the Coast
Guard requirements in 33 CFR part 183 which reference SAE J1527.117 Fuel hose for boats with
gasoline engines (excluding outboards) must meet the Class 1, Type A requirements which
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Draft Regulatory Impact Analysis
specify a maximum permeation rate of 100 g/m2/day at 23°C on ASTM Reference Fuel C118 (50
percent toluene, 50 percent iso-octane). Class 1 refers to hose that is used where liquid fuel is
normally continuously in the hose. Type A refers to hose that will pass a 21/2 minute flame
resistance test.
On a fuel containing an alcohol blend, permeation would likely be higher from these fuel
hoses. In fact, the SAE J1527 standard also requires Class 1 hose to meet a permeation rate of
300 g/m2/day on fuel CM15 (15 percent methanol). Although ethanol is generally less
aggressive than methanol, ethanol in the fuel would still be expected to increase the permeation
rate significantly through most fuel hoses. Based on the data presented in Appendix 5D,
permeation through nitrile rubber is about 50 percent higher when tested on Fuel CE10 (10
percent ethanol) compared to testing on Fuel C.
Fuel fill neck hoses are subject to a less stringent permeation standard under the Coast
Guard specifications because they are not normally continuously in contact with fuel (Class 2).
This relaxed standard is 300 g/m2/day on Fuel C and 600 g/m2/day on Fuel CM15 at 23°C.
Where marine fuel hose is typically extruded, fill neck hose is generally constructed by wrapped
layers on a mandrill. Fill neck hose is constructed with a larger inner diameter (1.5-2") to
accommodate higher fuel rates and with thicker, more heavily reinforced walls, to prevent
buckling and pinching.
Marine fuel hose is typically designed to be somewhat lower than the SAE J1527
requirements. Confidential data by one manufacturer supplying baseline marine fuel hose
suggested that their fuel feed hose is about 25 percent lower than the Class 1, Type A
requirement on Fuel C and about 35 percent lower on Fuel CM15. In their comments on the
2002 proposal for marine evaporative emission control, Lawrence industries stated that the
majority of their fill neck hose permeates in the range of 150 to 180 g/m2/day which is about half
of the 300 g/m2/day requirement required by the Coast Guard.119
We collected test data on marine hose permeation through contracts with outside
laboratories.120'121'122'123'124 Data was also available on a fuel feed hose testing funded by the
marine industry.125 All of the hose were prepared by soaking with liquid fuel for long enough
periods to stabilize the permeation rate. This data is presented in Table 5.4-1. Note that this data
shows somewhat lower permeation than was reported by manufacturers based on their own
testing. Especially in the case of the fuel feed hose, this may be a function of the hose
construction. This hose was purchased by the contractor without any knowledge of the hose
construction. Therefore, it is not known if this is a representative sample of a baseline hose
construction or if it contains some sort of barrier material.
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Feasibility of Evaporative Emission Control
Table 5.4-1: Permeation Rates for Baseline SAE J1527 Marine Fuel Hose
Hose Type
fuel feed hose
vent hose
fill neck hose
fill neck hose
fill neck hose
I.D.
3/8"
5/8"
1.5"
1.5"
1.5"
Fuel Type*
E10
Fuel CE10
E10
FuelC
FuelC
Fuel CE10
FuelC
E10
Fuel CE10
g/m2/day
43
88
37
95
98
109
87
164
123
123
274
Test Temperature
23 °C
28 °C
22-36 °C
temperature cycle
23 °C
23 °C
* E10 refers to gasoline with 10 percent ethanol
Although fuel hose used in personal watercraft is subject to 33 CFR part 183, personal
watercraft manufacturers do not use hose specified in SAE J1527. Fuel hose specifications are
contained in a separate recommended practice under SAE J2046.126 Under this practice, the
permeation requirement is 300 g/m2/day with testing performed in accordance with SAE J1527.
5.4.1.2 Other Marine Fuel Hose
Fuel hose used with outboard engines is not subject to 33 CFR part 183. This hose
includes the fuel line from the portable fuel tank to the engine and fuel hose on the engine itself
and is generally either constructed out of nitrile rubber with an abrasion resistant cover similar to
hose used in recreational vehicle applications or is constructed out of polyvinyl chloride (PVC).
One manufacturer of marine hose for use in outboard marine engines supplied permeation data
on five hose constructions tested at 23°C.127 This data is presented in Table 5.4-2 for Fuel C,
Fuel CE10, and Fuel CM15 (15 percent methanol). As shown by this data, hose permeation rates
can increase dramatically when tested on fuel blended with alcohol. Fuel lines connected to a
portable fuel tank are also generally fitted with a primer bulb which is also typically constructed
from nitrile rubber.
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Draft Regulatory Impact Analysis
Table 5.4-2: Permeation Rates for Baseline Fuel Hose [g/m2/day at 23°C1
Fuel Hose
C-464-D11
C-530-D2-CE
ECO/CPE
J30R7
CMC ESI 763
FuelC
195
5
228
426
141
Fuel CE10
420
183
402
279
290
Fuel CM 15
590
546
565
433
314
gasoline*
66
4
53
27
43
E10
192
74
131
126
103
* cited as Marathon 92
5.4.1.3 Small SI Equipment Hose
Fuel hoses produced for use in Small SI equipment are generally extruded nitrile rubber
with a cover for abrasion resistance. This hose is often equivalent to SAE J30 R7 hose which as
a permeation requirement of 550 g/m2/day at 23°C128 on ASTM Fuel C (50 percent toluene, 50
percent iso-octane). On a fuel containing an alcohol blend, permeation would likely be much
higher for these fuel hoses. R7 hose is made primarily of nitrile rubber (NBR). Based on the
data presented in Appendix 5D, permeation through NBR is 50 percent higher when tested on
Fuel CE10 (10 percent ethanol) compared to testing on Fuel C.
One manufacturer performed a study of several hose samples and various fuel types.129
Permeation testing was performed using the methodology in SAE J30. These hose samples
included SAE J30 R7, R8, and R9 hose. The R7 hose samples were constructed with an
acrylonitrile inner tube with a chlorosulfonated polyethylene cover layer. The R8 hose samples
were constructed using a epichlorohydrin ethyleneoxide copolymer. The R9 hose used a
fluoroelastomer barrier for the inner tube with an outer tube made of chlorosulfonated
polyethylene compound reinforced with a polyester braid. Over the two week tests, the study
showed a peak permeation rate after 4-6 days for R7 and R8 hose and a peak permeation rate
after 10-12 days for the lower permeating R9 hose. Table 5.4-3 below presents the two week
averages for each of the hose samples and test fuels. In this study, the hose manufacturers were
not identified, but the hose samples were each given a letter designation.
Table 5.4-3: Permeation Rates for SAE J 30 Fuel Hose [g/m2/day at 23°C1
Fuel Hose
SAE J30 R7 "mfr. D"
SAE J30 R7 "mfr. E"
SAE J30 R8 "mfr. B"
SAE J30 R8 "mfr. F"
SAE J30 R9 "mfr. A"
SAE J30 R9 "mfr. C"
FuelC
450
330
152
130
2
2
Fuel CE10
508
501
385
355
11
6
Fuel CE15
541
433
337
308
10
4
Fuel CM 15
587
707
620
545
73
55
Handheld equipment typically use smaller diameter hose made of a single material with
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Feasibility of Evaporative Emission Control
no cover. This fuel hose may either be extruded straight run hose or may be more complex
injection-molded designs. To determine baseline permeation emission rates from hose on
handheld equipment, testing was performed by industry using a modified SAE J30 weight loss
procedure.130 In this modified procedure, E10 fuel was used and the testing followed a 30 day
fuel soak intended to stabilize the permeation rate. Table 5.4-4 presents the test results.
Table 5.4-4: Handheld Product Fuel Line Permeation Test Data [E10 fuel at 23"C1
Hose Identification
90014
90015
90016
S3
S4
HI
H2
SI
S2
Construction
extruded
injection-molded
Material
NBR
NBR
NBR
NBR
NBR
NBR
NBR
NBR
NBR/PVC
g/m2/day
198
192
168
165
171
360
455
198
386
5.4.1.4 Fuel Effects on Hose Permeation
As shown in the data above, adding ethanol or methanol to the test fuel significantly
affects the permeation rate through fuel hoses. Because the SAE guidelines typically specify
Fuel C for testing, most of the hose data available in the literature is on Fuel C or some blend of
Fuel C and ethanol or methanol.
One study looked at the effect of fuel composition on the permeation of several materials
used in baseline hose constructions.131 This data suggests that Fuel C is a more aggressive fuel
with respect to permeation than gasoline. In addition, this data shows that permeation for these
materials is very low with diesel fuel. Table 5.4-5 presents the data from this study. Appendix
5D includes a table spelling out the acronyms for the hose materials in this table.
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Draft Regulatory Impact Analysis
Table 5.4-5: Permeation Rates by Fuel and Fuel and Hose Material [g/m2/day at 21°C]
Material
CFM
CO
ECO
ETER
39%ACNNBR
CSM
CR
FuelC
nil
150
190
230
300
490
640
CE10
35
270
390
400
420
575
690
CM10
nil
255
310
360
360
665
740
Indolene*
0.1
10
55
65
110
210
320
IE10
20
80
180
205
200
240
340
IM10
nil
125
150
165
200
300
385
Diesel
3
2
5
10
15
nil
10
"Indolene" refers to a fuel meeting the EPA specifications for certification gasoline
This difference in permeation between Fuel C and gasoline is likely due to the higher
aromatic content of Fuel C than of certification gasoline. A second study compared three
common fuel system materials on Fuel C and certification gasoline.132 Fuel C is made up of 50
percent toluene and 50 percent isooctane. As a result, it is half aromatics and half aliphatics. In
this study, the certification gasoline was observed to be 29 percent aromatics, 67 percent
aliphatics, and 4 percent olefms. The test results were indicative of the effect of aromatics on
permeation. Table 5.4-6 presents the permeation rate reported in g-mm/m2/day for three sample
materials: a low permeation fluoroelastomer (FKM), two medium permeation epichlorohydrins
(ECO) and two high permeation nitrile rubbers (NBR). This testing, which was performed at
24°C, gives a good comparison of the effect of gasoline versus Fuel C on permeation.
Table 5.4-6: Fuel C Versus Gasoline Permeation by Hose Material [g-mm/mVday]
Material
FKM-1
ECO-1
ECO-3
NBR-1
NBR-2
FuelC
3.3
180
282
570
705
Indolene*
1.2
33
45
255
510
% difference
-64%
-82%
-84%
-55%
-28%
"Indolene" refers to a fuel meeting the EPA specifications for certification gasoline
5.4.1.5 Vent Hose Permeation
Permeation occurs not only through hose walls that are in contact with liquid gasoline,
but also through surfaces exposed to fuel vapor. In the event that the fuel vapor represents a
saturated mix of air and fuel, we would expect permeation to be the same as that for exposure to
liquid fuel. In a fuel tank, the walls of the tank are readily exposed to saturated vapor as
discussed earlier in Section 5.3.1.4. In a fuel system hose not continuously exposed to liquid
fuel, the vapor concentration may be significantly lower than saturation for several reasons.
Clearly, if a hose is open to atmosphere, such as vent hose, there would be a gradient through the
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Feasibility of Evaporative Emission Control
hose ranging from saturated vapor in the fuel tank to fresh air outside of the fuel system. In
addition, if the tank is venting and drawing in air due to diurnal (or other) temperature changes,
then the fuel hose will regularly be exposed to varying vapor concentrations.
To investigate permeation rates for vent hose exposed to gasoline vapor, we contracted
with an outside laboratory to measure the permeation of fuel through marine hoses under various
venting configurations.133'134 The marine hose used in this testing met the USCG requirements
for SD/I vessels in specified in 33 CFR part 183 and SAE Recommended Practice J1527. Each
section of hose was connected to a metal fuel reservoir and exposed to liquid fuel for 8 weeks at
40°C to stabilize the permeation rate. The test fuel was EPA certification gasoline blended with
10 percent ethanol (E10) Each section of hose was then soaked for an additional 2 weeks at
40°C in the planned test configuration. After the soak, fresh fuel was added to the reservoirs and
permeation was measured in a mini-SHED. Hose sections were tested at constant temperature in
three configurations.
One section of hose was tested exposed to liquid fuel. Two sections of hose (1.5 and 5/8"
ID.) were tested with one end connected to the fuel reservoir and the other opened to
atmosphere through a fitting in the SHED. This configuration was intended to simulate vent
hose at constant temperature. A third configuration was also tested where three sections of hose
were configured as vent hose and tested over a 22.2-35.6°C one day diurnal sequence. This test
was intended to simulate vent hose in a fuel system exposed to fuel tank breathing caused by
temperature variation. The data in this testing, shown in Table 5.4-7, suggest that permeation
rates for vent lines are much lower than for hose that is regularly exposed to liquid fuel. This
result is likely due to a fuel concentration gradient in the hose which is largely due to one end
being exposed to fresh air.
Table 5.4-7: Effect of Venting on Hose Permeation with E10 [g/m2/dayl
I.D.
inches
1.5
0.625
0.625
0.625
0.625
Length
feet
1
3
3
3
3
Temperature
28°C (84°F) constant
22-36°C (72-96°F) diurnal
Liquid Exposure
123*
37
-
Vented to Atmosphere
3.3
5.8
4.3
4.5
4.9
* taken from Table 5.4-1 on a similar hose for comparison
The marine industry also funded permeation testing on vent hose exposed only to fuel
vapor and air.135 The vent line hose was preconditioned by attaching the hose to a 55 gallon steel
drum containing commercial gasoline containing 10 percent ethanol and setting the drum outside
during the summer. A carbon canister was attached to the end of the hose to simulate a vent line
with diurnal emission control. Permeation was measured after 90, 120, 150, and 180 days of
preconditioning. Because of the large size of the test rig, weight loss testing could not be
performed. Instead, a sleeve was fitted over the hose and nitrogen was flowed through the sleeve
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Draft Regulatory Impact Analysis
to a carbon trap. The change in the weight of the carbon trap was then measured to determine
the permeation rate. As with the fill neck testing, the hose was configured to run vertically from
the top of the fuel reservoir (55 gallon drum). Repeat testing was performed on this hose and
both values for each hose are presented in Table 5.4-8. The permeation rates for this testing
were lower than for similar hose exposed to liquid fuel. Fuel vapor stratification may have been
caused by a number of factors including breathing of fresh air into the tank during ambient
cooling periods, gravity, and a limiting diffusion rate.
Table 5.4-8: Industry Test Data on Marine Vent Hose Exposed to Fuel Vapor
Hose manufacturer
#1
#2
Permeation [g/m2/day]
2.7,2.2
2.7,2.8
8.9,8.5
5.7,6.6
2.2,2.0
2.5,2.2
2.5,2.6
5.4.1.6 Vapor Hose Permeation
Even in a vapor hose that is sealed at one end, stratification may occur for a fuel system
due to gravity. An example of vapor hose would be fuel fill neck hose with a sealed cap.
Because fuel vapor is heavier than air, even a large diameter hose may see stratification of fuel
vapor concentration if it reaches high enough above the surface of the liquid fuel. The
stratification of vapor molecules happens slowly but would likely be observed under static
conditions. Another cause of low vapor concentration in fuel system hose may occur due to the
properties of diffusion discussed above in Section 5.1.3. If the hose diameter is small compared
to its length, diffusion of vapor into the hose may be the rate limiting step rather than the
permeation rate through the hose. In other words, the fuel vapor may enter the hose much slower
than rate at which it could permeate through the hose. This effect could be combined with the
other effects discussed above to cause lower permeation for fuel hose exposed to vapor rather
than liquid fuel.
The marine industry funded permeation testing on fill neck exposed only to fuel vapor.136
For the fill neck hose, a three foot section of hose was attached to the top of a five gallon metal
fuel reservoir and configured vertically. The fuel reservoir was filled half-way with gasoline
containing 10 percent ethanol. Approximately every 30 days, this hose/reservoir assembly was
weighed for five days in a row. After the fifth day, the fuel in the reservoir was replaced with
fresh fuel. Testing was performed at 23°C. The only liquid fuel exposure was a weekly
inversion of the assembly for about 1 minute. No attempt was made to simulate fuel slosh that
would be likely be seen in a boat in the water. Also the hose was configured straight up and
down rather than in a more representative configuration as seen on a boat that would include
more horizontal orientation for most of the length of the hose. Repeat testing was performed on
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Feasibility of Evaporative Emission Control
the hose.137 During this repeat testing, permeation was also measured for the same fill neck hose
exposed to liquid fuel.
Four of the fill neck hose constructions were specified as meeting the A2 designation in
SAE J1527. The other two fill neck hose samples were not identified except that they are made
by a hose manufacturer that is known to offer fill neck hose with and without a fluoroelastomer
barrier. Table 5.4-9 presents the test results which show much lower permeation rates for fill
neck hose exposed vapor rather than liquid fuel. Because the end of the hose was not exposed to
atmosphere, and because the hose was situated well above the surface of the liquid fuel in a
vertical fashion, stratification may have occurred in the hose largely due to gravity. This
stratification would be expected to lower the vapor concentration in the hose and therefore lower
permeation.
Table 5.4-9: Industry Permeation Data on Marine Fill Neck Hose [g/mVday]
Hose manufacturer
#1
#2
Vapor Exposure
4.8,4.8
4.5,4.4
4.7,4.8
4.7,4.7
1.3, 1.1
0.6,6.9
Liquid Exposure
129
114
113
121
5.6
8.5
The marine industry testing was all performed on static test rigs with vertically oriented
hose. No consideration was given to how sloshing the test configuration, as would be seen in a
boat in the water, would have affected the results. For in-use equipment, especially boats in the
water, the fuel is sloshed regularly due to operation or waves. This sloshing may mix up the
vapor in the tank and hose. The industry test program also did not consider how a different hose
configuration (i.e. more horizontally oriented) would have affected the results. Fill neck hose in
boats often runs nearly horizontal from the tank to the edge of the boat, then runs more vertically
near the fill port.
We contracted with an outside test lab to
investigate the effects of fuel slosh and hose
configuration on permeation through marine fill
neck hose.138 All of the testing was performed
on 3 foot sections of 1.5" ID. marine fill neck
hose. Testing was performed in each of the
three configurations shown in Figure 5.4-1. For
each fuel vapor exposure test, the hose was first
preconditioned by subjecting it to liquid fuel for
5 weeks followed by fuel vapor for an
additional 5 weeks. For the liquid fuel exposure
tests, the hose was soaked with liquid fuel for
Figure 5.4-1: Hose Test Configurations
Liquid
Horizontal
Vertical
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Draft Regulatory Impact Analysis
10 weeks. Fuel soaking was performed at 40°C.
A total of eleven tests were run. For each configuration, testing was performed on three
fuels: Fuel C, CE10, and E10. The liquid fuel exposure tests were performed in the static
position, while the fuel vapor exposure tests were performed with the fuel tanks on a slosh table.
Sloshing was performed at 15 cycles per minute with a deviation of+7° to -7° from level to
simulate movement that might be seen on a boat. An additional two tests were performed to
measure permeation through vapor hose in the vertical and horizontal positions without sloshing.
Permeation was measured similar to the industry testing using weight loss measurements of the
entire test rigs at 23 °C.
The test results from this testing are presented in Table 5.4-10. It was observed that
permeation was much lower for vapor fuel exposure than for liquid fuel exposure. Fuel
permeation was significantly higher for the horizontal hose configuration than for the vertical
hose configuration. This suggests that a large amount vapor stratification was occurring for the
vertical hose, while some fuel vapor was collecting in the horizontal hose. The fuel sloshing
applied in this testing doubled the permeation through the horizontal hose. Regardless of fuel
slosh, no measurable permeation was observed through the vertically oriented hose. Permeation
emissions were observed to be about twice as high on fuel CE10 than on Fuel C or E10.
Table 5.4-10: Effect of Hose Configuration, Vapor Exposure,
and Test Fuel on Marine Fill Neck Hose Permeation at 23°C
Hose Configuration
horizontal
vertical
Vapor Exposure
stationary
sloshed
sloshed
sloshed
stationary
sloshed
sloshed
sloshed
liquid soak
Test Fuel
CE10
CE10
E10
FuelC
CE10
CE10
E10
FuelC
CE10
E10
FuelC
Permeation [g/m2/day]
4.6
9.1
4.6
9.1
0.0
0.0
0.0
0.0
273.7
123.2
123.2
In another study, the effects of liquid fuel versus vapor were studied in which the vapor
hose was not open to atmosphere.139 The fuel hose used for this testing was purchased over the
counter and was labeled as SAE J30 R7. Further investigation of the hose revealed that this
particular grade is made of lower permeation materials than typical Small SI hose constructions.
It was constructed of NBR with a relatively high ACN blend (39 percent) and an ECO cover was
used. This construction was originally intended to allow the hose to be painted with a lacquer-
based paint, then dried in an oven. Although this is a somewhat atypical hose construction, the
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Feasibility of Evaporative Emission Control
test results should still reflect the effects of liquid versus vapor on permeation.
In this testing, all of the fuel hose was preconditioned by soaking in liquid fuel for 5
weeks at about 40°C. This soak was then repeated, except that half of the hose sections were
then exposed only to fuel vapor resulting from attaching the hose to the top of a metal fuel
reservoir. Three fuels were used; California certification gasoline (CARB II), EPA certification
gasoline (gasoline), and EPA gasoline blended with 10 percent ethanol (E10). After the soak
period, the fuel was refreshed and weight loss testing was performed at 23°C. Table 5.4-11
presents the test results. Note that each data point in this table is the average of three hose
samples. In this testing, the end of the hose was plugged and the hose was configured
horizontally. The lower permeation rates for vapor exposure were likely the result a low vapor
concentration in the hose. This low vapor concentration may have been caused because the
diffusion into the long narrow hose may have been the rate limiting effect rather than the
permeation rate through the hose.
Table 5.4-11: Fuel Hose Permeation with Vapor vs. Liquid Exposure [g/mVday]
Test Fuel
CARB II
Gasoline
E10
Liquid Exposure
35.8
44.5
80.3
Vapor Exposure
0.3
0.1
0.7
5.4.2 Hose Permeation Reduction Technologies
Materials used in current automotive fuel lines are two to three orders of magnitude less
permeable than nitrile hoses.140 In automotive applications, multilayer plastic tubing, made of
fluoropolymers is generally used. An added benefit of these low permeability lines is that some
fluoropolymers can be made to conduct electricity and therefore can prevent the buildup of static
charges.141 Although this technology can achieve more than an order of magnitude lower
permeation than barrier hoses, it is relatively inflexible and may need to be molded in specific
shapes for each Small SI application. For marine applications, this tubing would not likely meet
the Coast Guard or AB YC durability specifications for fuel and vent hose.
Thermoplastic fuel lines for automotive applications are generally built to SAE J2260
specifications.142 Category 1 fuel lines under this specification have permeation rates of less than
25 g/m2/day at 60°C on CM15 fuel (15 percent methanol). One thermoplastic used in
automotive fuel line construction is polyvinylidene fluoride (PVDF). Based on the data
presented in Appendix 5D, a PDVF fuel line with a typical wall thickness (1 mm) would have a
permeation rate of 0.2 g/m2/day at 23°C on CM15 fuel. However, manufacturers involved in the
boat building industry have commented that this fuel line would not be flexible enough to use in
their applications because they require flexible rubber hose to fit tight radii and to resist
vibration. They also commented that the hose they use must pass the Coast Guard flame
resistance requirements.143'144
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Draft Regulatory Impact Analysis
Recreational vehicle manufacturers are required to use hose that meets a permeation
standard of 15 g/m2/day at 23°C on gasoline blended with 10 percent ethanol (E10). Low
permeation hose constructions that have been identified for these applications could also be used
in Small SI equipment. We believe that the same barrier materials that will be used for
recreational vehicle hose can also be used for marine hose constructions. Marine hose
constructions generally meet the Coast Guard flame resistance requirements either through the
use of a flame-resistant cover, or by increasing the wall thickness. Therefore, the addition of an
inner permeation barrier would not be expected to affect the flame resistance of the hose.
Several low permeation hose constructions are discussed below. Even though most of this data
is on hoses not designed for marine applications, the barrier technology can be used in marine
hose.
We are proposing that fuel and vapor hose meet our standards on E10 fuel for two
reasons. First, ethanol is commonly a component of in-use fuels. Second, for many materials
used in hose constructions, permeation would likely be much higher for fuel containing ethanol.
For instance, a typical barrier material used in barrier hose constructions is FKM. Based on the
data presented in Appendix 5D for FKM, the permeation rate is 3-5 times higher on Fuel CE10
than Fuel C. Therefore, a hose meeting 15 g/m2/day at 23°C on Fuel C may actually permeate at
a level of 40-50 g/m2/day on fuel with a 10 percent ethanol blend.
There are lower permeation fuel hoses available today that are manufactured for
automotive applications. These hoses are generally used either as vapor hoses or as short
sections of fuel line to provide flexibility and absorb vibration. One example of such a hose145 is
labeled by General Motors as "construction 6" which is a multilayer hose with an inner layer of a
fluoroplastic known as THV sandwiched in inner and outer layers of a rubber known as ECO.5
A hose of this construction would have less than 8 g/m2/day at 40°C when tested on CE10.
Permeation data on several low permeation hose designs were provided to EPA by an
automotive fuel hose manufacturer.146 This hose, which is as flexible as non-barrier hose, was
designed for automotive applications and is available today. Table 5.4-12 presents permeation
data on three hose designs that use THV 800 as the barrier layer. The difference in the three
designs is the material used on the inner layer of the hose. This material does not significantly
affect permeation emissions through the hose but can affect leakage at the plug during testing (or
connector in use) and fuel that passes out of the end of the hose which is known as wicking. The
permeation testing was performed using the ARE 18-41°C diurnal cycle using a fuel with a 10
percent ethanol blend (E10).
5 THV = tetrafluoroethylene hexafluoropropylene, ECO = epichlorohydrin/ethylene oxide
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Feasibility of Evaporative Emission Control
Table 5.4-12: Hose Permeation Rates with THV 800 Barrier over ARE Cycle (g/m2/day)
Hose Name
CADBAR9610
CADBAR9710
CADBAR9510
Inner Layer
THV
NBR
FKM
Permeation
0.16
0.17
0.16
Wicking
0.00
0.29
0.01
Leaking
0.02
0.01
0.00
Total
0.18
0.47
0.18
The data presented above shows that there is hose available that can easily meet the
proposed hose permeation standard on E10 fuel. Although hose using THV 800 is available, it is
produced for automobiles that will need to meet the tighter evaporative emission requirements in
the upcoming Tier 2 standards. Hose produced in mass quantities today uses THV 500. This
hose is less expensive and could be used to meet the proposed hose permeation requirements.
Table 5.4-13 presents information comparing hose using THV 500 with the hose described
above using THV 800 as a barrier layer.147 In addition, this data shows that permeation rates
more than double when tested on CE10 versus Fuel C.
Table 5.4-13: Comparison of Hose Permeation Rates with THV 500 and 800 (g/m2/day)*
Hose Inner
Diameter, mm
6
8
10
THV 500
FuelC
0.5
0.5
0.5
Fuel CE10
1.4
1.4
1.5
THV 800
FuelC
0.2
0.3
0.2
Fuel CE10
0.5
0.5
0.5
Calculated using data from Thwing Albert materials testing (may overstate permeation)
We contracted with an independent testing laboratory to test several samples of SAE J30
R9 hose and a sample each of automotive vent line and fill neck hose for
permeation.148'149'150'151'152'153 The fuel and vapor hoses had a six mm inner diameter. The test lab
used the SAE J30 test procedures for R9 hose with both Fuel C and Fuel CE10. Most of the R9
fuel hose was supplied by recreational vehicle manufacturers who also supplied information on
the materials used in the construction of the hose as well. We purchased one sample of the R9
hose (which was labeled as such) from a local auto parts store without knowing its construction.
Two additional R9 hoses were tested by a fuel hose manufacturer on fuel CE10 after a four week
soak.154 The SAE permeation specification for R9 hose is 15 g/m2/day at 23 °C on Fuel C. The
R9 hose tested all met this limit, even on ethanol blend fuels which typically result in higher
permeation. The automotive vent line showed similar results, but the automotive fill neck
showed much lower permeation. Table 5.4-14 presents the test data on the above hose samples.
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Draft Regulatory Impact Analysis
Table 5.4-14: Test Results on Commercially Available Hose Samples (g/m2/day)
Hose Sample
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
Automotive vent line
Automotive fill neck
Construction
FKM/ECO
FKM/ECO
FKM/NBR/CM
FKM/ECO
FKM/ECO
PVC/EEC
FKM barrier
fluorine/hydrin
unknown
FKM barrier
FKM barrier
unknown
unknown
FuelC
-
-
-
-
-
-
-
-
10.1
-
-
10.9
0.33
Fuel CE10
7.6
2.1
4.2
10.9
5.2
11.6
6.6
9.0
12.1
4.2
6.7
9.0
0.49
Another hose construction that can be used to meet the marine hose permeation standards
is known as F200 which uses Teflon® as a barrier layer. Teflon® has a permeation rate of 0.03-
0.05 g-mm/m2/day on 15 percent methanol fuel. F200 hose is used today to meet SAE J30 Rl 1
and R12 requirements for automotive applications. Table 5.4-15 presents data on permeation
rates for several F200 constructions.155
Table 5.4-15: F200 Typical Fuel Permeation
Film Thickness [mils]
2
2
2
2
2
1
1
Hose Diameter [in.]
0.375
0.275
0.275
0.470
0.625
0.625
1.5
Fuel
TF-2
TF-2
M25
CE10
CE10
CE10
CE10
g/m2/day @23°C
~
~
0.5
~
~
~
1.5
g/m2/day @40°C
0.7
1
4
3
3
4
~
Low permeability hoses produced today are generally constructed with a barrier material
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Feasibility of Evaporative Emission Control
layer. There are hoses used in some marine applications with a thermoplastic layer (either nylon
or EVOH) between two rubber layers to control permeation. Because the thermoplastic layer is
very thin, on the order of 0.1 to 0.2 mm, the rubber hose retains its flexibility. Through contract
with two independent labs, we tested three samples of marine barrier hose that was available
prior to our initial proposal for marine permeation emissions. This hose included two 3/8"
samples and one 5/8" sample which all used nylon as the permeation barrier. These hose
constructions are used in some sterndrive and inboard applications. Table 5.4-16 presents the
permeation test results at 23°C.156'157'158'159'160'161
Table 5.4-16: Test Results on Available Barrier Marine Hose Samples (g/m2/day)
Hose Description
3/8" marine barrier fuel hose
5/8" marine barrier fuel hose
Lab 1
FuelC
0.80
~
Fuel CE10
5.2
11.6
3.4
Lab 2*
FuelC
0.36
0.76
* average of three tests
Similar testing was performed by the marine industry on commercially available low
permeation marine hose.162 In this testing, the 3/8" ID. fuel hose samples were connected to
metal fuel reservoirs and soaked with gasoline containing 10 percent ethanol at 23 °C for 180
days. The weight of the container/hose assembly was measured for five days in a row
approximately every 30 days. The fuel was replaced with fresh fuel after each series of weight
measurements. The test report did not specify details on the hose constructions. However, based
on the manufacturer part numbers, several of the hoses in this test program were determined to
use a nylon barrier layer. One of the hoses included was a baseline rubber construction meeting
Coast Guard requirements for SD/I fuel hose. Repeat testing was performed on the hose.163
During this repeat testing, permeation was also measured for the same hose exposed to fuel
CE10. Although the permeation rate was generally higher on fuel CE10, the barrier hose
permeation rates were still well below the proposed standard. Table 5.4-17 presents the results
of this testing.
Table 5.4-17: Permeation Results for Commercially Available Marine Barrier Hose
Tested at 23°C with Gasoline Containing 10% Ethanol (g/mVday)
Hose Construction
SAE J1527 Al constructions with nylon barrier
not reported
Gasoline with 10% Ethanol
6.2,5.2
5.6,5.1
4.4,3.8
4.4,3.2
0.4,0.1
CE10
6.1
6.7
10.0
12.1
0.0
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Draft Regulatory Impact Analysis
After the initial proposal for marine permeation emissions, two marine hose
manufacturers developed hose samples using the F200 hose construction. In addition, other hose
manufacturers supplied samples of barrier hose using the F200 hose construction and using
THV800 as a barrier layer. These manufacturers stated that they could make marine hose using
the same barrier construction. We contracted to have these hose samples permeation tested on
fuel CE10 at 23°C following a four week soak.164 These test results are presented in Table 5.4-
18.
Table 5.4-18: Permeation Test Results on New Marine Barrier Hose Constructions
Application
marine fill neck
marine fuel hose
fuel hose
fuel hose
Barrier Material
Teflon (F200)
Teflon (F200)
Teflon (F200)
THV800
I.D. [inches]
l'/2
3/8
1/4
1/4
g/m2/day
0.2
5.0
3.8
5.1
Currently, the Coast Guard requires that fuel pumps on engines be located on or near the
engine to minimize the length of high pressure fuel lines on the vessel. However, at least one
manufacturer sells boats with the high pressure fuel pump in the fuel tank. They received a
waiver from the Coast Guard by using fuel lines that use either a glass fiber or stainless steel
braid cover and quick connect end fittings that are designed to withstand very high pressures
(much higher than would be seen on a boat).165 This particular fuel line construction also uses
Teflon® as a barrier layer. Table 5.4-19 presents permeation test data on this hose.166
Table 5.4-19: Permeation Test Data on Reinforced Fuel Hose
Application
Marine
Outdoor Power
Equipment
I.D. [inches]
0.31
0.25
0.19
0.31
0.25
0.19
Temperature
23°C
60°C
Fuel
CE10
CM15
g/m2/day
0.05
0.08
0.05
0.52
0.93
1.08
Primer bulbs are typically injection-molded out of nitrile rubber. Fuel lines for some
handheld equipment are manufactured in a similar manner. Low permeation primer bulbs and
fuel lines could be manufactured using a similar process by molding them from a
fluoroelastomer such as FKM. Fluoroelastomers, such as FKM, have similar physical properties
as nitrile rubber but are much more fuel-resistant. If the primer bulb or fuel line were molded
out of a FKM with a sufficient flurorine concentration, the permeation rate would be less than
proposed fuel line permeation standard. Alternatively, primer bulbs could be manufactured to
5-82
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Feasibility of Evaporative Emission Control
meet the proposed standards by molding a fluoroelastomer inner liner with a nitrile shell to
reduce costs. Other materials may be applicable as well (see tables of material properties in
Appendix 5D).
Under their rule for small offroad equipment, California may issue executive orders to
manufacturers with low emission products. As of August, 2006, ARB has issued 24 executive
orders for low permeation fuel lines.167 The California fuel line permeation standard is 15
g/m2/day tested at 40°C on California certification fuel. However, many of the manufacturers
tested their products on CE10 fuel which results in significantly higher permeation rates. Some
manufacturers even tested at 60°C. In all cases, the test results were below the 15 g/m2/day
standard, even under the more challenging test conditions. Table 5.4-20 presents the test results
for the fuel lines with ARB executive orders. Note that the reported emissions are the average of
5-6 test samples.
5-83
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Draft Regulatory Impact Analysis
Table 5.4-20: ARB Fuel Hose Executive Orders for Small Offroad Equipment
EO#
C-U-06-016
C-U-06-001
G-05-016
G-05-017
G-05-019
C-U-05-004
C-U-05-010
G-05-019*
G-05-015a
C-U-05-001
C-U-06-001*
C-U-06-001*
C-U-06-020
C-U-05-014
C-U-06-021
C-U-06-002
C-U-06-011
C-U-05-011
C-U-06-017
C-U-05-013
C-U-05-006
C-U-05-012
C-U-05-003
G-05-018
C-U-05-009
C-U-06-010
C-U-05-002
ID. [mm]
4.8
6.0
6.4
6.4
6.4
6.4
6.4
6.4
7.9
8.0
6.0
6.0
4.5
6.4
6.4
6.4
6.4
2.0
3.5
4.0
4.0
4.0
4.5
4.8
4.8
4.8
6.4
Test Fuel
CE10
CE10
CE10
CE10
CE10
CE10
CE10
CE10
CE10
CE10
CM15
FuelC
Indolene
Indolene
Indolene
Indolene
Indolene
Phase II
Phase II
Phase II
Phase II
Phase II
Phase II
Phase II
Phase II
Phase II
Phase II
Temperature
40
40
40
40
40
40
40
60
60
60
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
g/m2/day
3.75
1.42
4.62
5.97
0.02
12.3
10.6
0.26
11.1
8.22
3.77
0.78
3.20
8.20
7.40
5.00
12.7
4.63
10.8
1.22
10.3
7.33
12.3
0.87
3.94
4.69
3.76
* fuel tube
5.4.3 Low Temperature Hose Materials
In some applications, molded fuel hoses are used rather than simple extruded fuel hose.
These fuel hoses are typically molded out of nitrile rubber (NBR) or a fluoroelastomer such as
FKM. FKM is essentially rubber impregnated with fluorine which results in good fuel
permeation resistance. Manufacturers of handheld equipment that may be used in very cold
weather have stated that they must use nitrile rubber because the FKM material may become
brittle at very low temperatures.168 Examples of such equipment are ice augers and chainsaws.
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Feasibility of Evaporative Emission Control
Industry has not raised an issue with the capability of using extruded multi-layer hose in
cold temperature applications. This type of hose construction has been demonstrated for low
temperature use in automobiles and snowmobiles. Extruded fuel hose meeting SAE and ASTM
standards is available today which meets a widespread set of safety and durability requirements.
Industry has stated that for some applications, such as chainsaws, that extruded fuel hose will not
work. In these applications, injection molding is used to manufacture complex fuel hose
geometries designed to account for high vibration of the equipment. This vibration generally
results in different motion patterns for the carburetor and fuel tank resulting in variable distances
between the two.
Industry presented information on FKM fuel lines that became brittle and cracked at very
low temperatures.169'170 However, this information was was based on an FKM compound without
a low temperature additive package. There are a wide range of FKM products available on the
market. Many of these fluoroelastomers are designed for use at low temperatures.171'172 For
instance, low temperature o-rings are common in automotive applications.173'174'175 Low
temperature grade FKM products are available with a glass transition temperature as low as -
40°C and a brittleness point as low as -60°C.176 However, low temperature grade FKM products
typically cost several times as much as FKM products intended for less severe temperatures. In
addition, these materials have not been demonstrated for use in molded fuel lines for handheld
applications.
A lower cost option may be to blend a standard fluorosilicone such as FVMQ with a
standard grade FKM. The fluorosilicone brings very low temperature characteristics to the
blend. However, the permeation resistance is not nearly as good as for FKM products. The
blended product would be intended to create a balance between cost, permeation, and low
temperature properties.177 This product is currently used in automotive o-rings. However, it is
not clear if this material could be molded into fuel lines that would meet the appropriate design
criteria for handheld applications.
A new material, called F-TPV, has been developed that is a dynamically vulcanized
combination of fluorothermoplastic resin and fluoroelastomer compound.178 The mix of the two
materials can be varied to trade-off permeation resistance with material hardness. This material
has been shown to have a permeation rate ranging from 3 to 30 g-mm/m2/day on fuel CE10 at
60°C. Rubber hose molded out of even the softest version of this material would be expected to
be capable of achieving a permeation rate well below the proposed standard. In addition, the
impact brittleness temperature is below -50°C for the full range of material blends discussed
above. Finally, the cost of this material is much lower than for low-temperature FKM products.
Further development efforts would be necessary to determine the suitability of this material for
fuel lines on handheld equipment.
Table 5.4-4, above, presents permeation data on several samples of NBR fuel lines used
on handheld equipment today. The permeation rates from these fuel lines range from 165 to 455
g/m2/day with E10 fuel at 23 °C. Later discussions with industry revealed that the NBR hose
with the lower permeation rates had higher acrylonitrile (ACN) contents. Although high ACN
rubber cannot achieve the same low permeation rates as FKM or F-TPV, some permeation
5-85
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Draft Regulatory Impact Analysis
reductions could still be achieved with this material.
5.5 Other Evaporative Emissions
5.5.1 Other Venting Losses
Hot soak emissions occur after the engine is turned off, especially during the resulting
temperature rise. The primary source of hot soak emissions is the evaporation of the fuel left in
the carburetor bowl. Other sources can include increased permeation and evaporation of fuel
from plastic or rubber fuel lines in the engine compartment.
Refueling emissions occur when the fuel vapors are forced out when the tank is filled
with liquid fuel. At a given temperature, refueling emissions are proportional to the volume of
the fuel dispensed into the tank. Every gallon of fuel put into the tank forces out one-gallon of
the mixture of air and fuel vapors. Thus, refueling emissions are highest when the tank is near
empty. Refueling emissions are also affected by the temperature of the fuel vapors and
dispensed fuel. At low dispensed fuel temperatures, the fuel vapor content of the vapor space
that is replaced is lower than it is at higher temperatures because of the cooling effect on the
vapor in the fuel tank.
In automotive applications, the carbon canister is sized not only to capture diurnal
emissions, but refueling, hot soak, and running loss emissions as well. With an engine purge, the
canister would effectively capture running loss emissions and hot soak emissions because the
canister would presumably be nearly empty after a short period of operation. For the canister to
be effective at collecting refueling emissions, it would need to be purged before the refueling
event. However, even without a purged canister, refueling emissions could be minimized by
matching the geometry of the fuel fill opening to the fuel pump nozzle. By minimizing the open
space in the fuel fill opening around the nozzle, less air will be entrained which will minimize
vapor generation during the refueling event. This will not help control the expulsion of vapor
that is displaced by liquid fuel.
5.5.2 Refueling Spitback/Spillage
Installed fuel systems on boats are typically open vented. The exception to this is PWC
which have sealed fuel tanks with pressure relief valves, largely to prevent spillage of fuel during
operation. For larger boats, fuel spillage during operation is less of an issue; however, it is
common for fuel to be lost to the environment during refueling or shortly thereafter.179'180 There
are several mechanisms that lead to fuel loss due to a refueling event. These mechanisms
include restrictions in the fill neck, fuel flowing out the vent line, and expansion of fuel in the
tank.
The American Boat and Yacht Council (AB YC) has a voluntary refueling standard
designed to help prevent fuel from backing up the fill neck during a refueling event.181 This test
requires that no fuel back up the fill neck when a fuel tank in a boat is filled from 25 to 75
percent full at a fill rate of 9 gallons per minute. This test is apparently designed to make sure
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Feasibility of Evaporative Emission Control
that the fill neck does not have a restriction that may cause fuel to back up the fill neck during
refueling. To prevent fill from backing up the fill neck, fill necks are typically made of large
diameter hose which is reinforced to prevent kinking. In addition, the fuel fill opening is
typically positioned higher than the vent line. This test does not consider fuel overflow that may
occur from filling a marine tank to 100 percent full. In addition, the full rate may be too low to
require a design that would work in typical in-use situations. One survey on 19 marinas saw a
range of 8 to 25 gallons per minute for gasoline fill nozzles with an average of 14 gallons per
• 189
minute.
The most common refueling spillage today is overflow out the vent line. Typically the
vent line is the path of least resistance for fuel overflow. Boats typically do not have a
mechanism that prevents fuel tanks from filling all the way to the top. In fact, the fill and vent
hose are attached to the top of the fuel tank and are often filled with fuel in addition to the tank.
Because the vent hose exits the boat lower than the fill neck opening, the tank can be filled until
fuel begins to exit through the vent hose. In addition, fuel may expand in the fuel tank when
cool fuel is pumped into the fuel tank on a warm day. This expansion can cause additional fuel
overflow out the vent line.
A number of devices have been produced to help control fuel spillage during refueling.
These devices include liquid/vapor separators, combination deck fills and vents, and fuel flow
monitoring systems. A study was performed by Boat US Foundation to evaluate the
effectiveness of several of these systems which are currently available on the market.183 The
results of this study are discussed below.
Liquid/vapor separators are valves that are installed in the fuel line. The typical design is
for the valve to contain a ball that rises when liquid fuel reaches it which closes the vent to liquid
fuel. As the tank fills, fuel backs up the fill neck, allowing the automatic shut-off on the nozzle
to stop the fuel flow. The study found that these systems typically worked best at lower fuel fill
rates and that the larger units were more effective. The effectiveness of the larger units was
probably because they essentially included a reservoir, allowing extra room for fuel expansion.
For the smaller units, the testing consistently showed fuel backing up the fill neck too quickly for
the automatic shut-off valve to engage and fuel spit back out of the deck fill.
In a vented deck fill design, the vent line is routed back to the top of the fill neck. The
intent is that the fuel surging out of the vent line would return to the fill neck and back to the
tank. The study found that the combination vented deck fills significantly reduced
spitback/spillage, but still needed to be used with some caution. One issue was that even when
the fuel came back up and shut off the nozzle, pressure in the fuel tank would cause fuel to
continue to rise in the line and spill onto the deck. Another manufacturer has a similar device
except that a clear section of tubing that redirects the fuel overflow from the vent line to the fill
neck. The operator only attaches this tubing during refueling. Because the tubing is clear, the
operator can see when the fuel is coming out of the vent and can manually slow down or stop the
fuel flow.
Fuel flow monitoring systems are designed to keep track of fuel usage by measuring fuel
5-87
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Draft Regulatory Impact Analysis
flowing to the engine. The study did not present definitive results for the use of flow meters to
accurately refuel the tank without overfill.
Where a carbon canister is used in the vent line for diurnal vapor control, it would be
important to include a device to prevent liquid fuel from entering the canister. This device could
take the form of a floating ball valve, limited flow orifice, or other liquid/vapor separation
mechanism. In addition, this device could be positioned in such a way as to prevent the tank
from filling all the way to the top. For instance, the vent fitting could reach down into the fuel
tank. Leaving a vapor space in the fuel tank would give room for fuel in the tank to expand.
In automotive applications, carbon canisters have been used for many years in vehicles
that also meet fuel spit-back standards set by EPA. In typical automotive fuel systems, the fuel
shut-off on the nozzle is tripped before the fuel comes back out the fill neck. It is common to
have a narrow tube parallel to the fill neck reach into the fuel tank at the desired peak fill level of
the tank. The narrow tube connects to the fill neck near the top where the small hole on the
nozzle would be. When fuel splashes on this small hole, the vacuum draw is broken and the
shut-off device is triggered. Fuel travels up the narrow tube more quickly than up the fill neck
and triggers the nozzle shut-off well before fuel spit-back can occur.
At least one company is developing a similar design for use in boats. Testing has been
performed on one system by an independent laboratory that also performs ABYC and Coast
Guard tests for the marine industry. During the testing, a fuel tank was filled 30,000 times, using
this fuel system configuration, without any spillage.184 Also, this fuel system configuration
creates a vapor space in the top of the tank which allows fuel to expand during heating, thereby
preventing fuel spillage due to expansion of the fuel in the tank.185 This system has since been
modified to be adaptable to any fuel tank with a fuel sending unit based on the standard SAE 5-
hole pattern. The updated system was tested using a similar methodology as in the Boat US
study discussed above and underwent 25,000 refueling events at 15 gallons per minute without
experiencing any spills.186 Pictures and video of this system are included in the docket.
5.6 Evaporative Emission Test Procedures
This section discusses test procedures for measuring fuel line permeation, fuel tank
permeation, and diurnal emissions.
5.6.1 Hose Permeation Testing
We propose for hose permeation to be measured at a temperature of 23 ± 2°C using the
weight loss method specified in SAE J30.187 In this method, one end of a specified length of
hose is connected to a metal reservoir while the other end is plugged. Test fuel is then added to
the reservoir at a volume high enough to ensure that the hose is filled with fuel. Once any air
bubbles have been removed from the hose, the reservoir is sealed and the entire system is
weighed. Permeation is determined by weighing the system every 24 hours and noting the
weight loss. After each weighing, the fuel is mixed by inverting the assembly, then returning it
to its original position.
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Feasibility of Evaporative Emission Control
We are proposing two modifications to SAE J30 that are consistent with our current
requirements for recreational vehicles and highway motorcycles. First, the test fuel must be
ASTM Fuel C188 (50 percent toluene, 50 percent iso-octane) blended with 10 percent ethanol.
This fuel is known as CE10 and is commonly used in industry standards and test procedures such
as in SAE recommended practices. Section 5.4, and Appendix 5D presents permeation data for
several hose constructions and materials used in hose constructions on fuels with and without
ethanol. As shown in this data, adding ethanol to the test fuel significantly increases permeation.
Standard recommended practice for hose testing uses Fuel C, or some blend of Fuel C and either
ethanol or methanol. This test fuel is generally more aggressive than standard gasoline.
Although hoses are not generally exposed to Fuel C in use, the level of the standard was based
on testing using Fuel C and Fuel C blends. In addition, most of the test data on low permeation
hose presented in this Chapter is based on fuel CE10. For these reasons, we believe that it is
appropriate to allow Fuel CE10 for hose testing.
The second modification is that the hose must be preconditioned by filling the hose with
fuel and soaking long enough to ensure that the permeation rate has stabilized. We are
proposing a soak period of 4 weeks at 23 ± 5°C. If a longer time period is necessary to achieve a
stabilized permeation rate for a given hose design, we would expect the manufacturer to use a
longer soak period (and/or higher temperature) consistent with good engineering judgement. For
instance, thick-walled marine fuel hose may take longer to reach a stable permeation rate than
thinner-walled hose used in Small SI applications.
Alternatively, for purposes of submission of data at certification, permeation could be
measured using alternative equipment and procedures that provide equivalent results. To use
these alternative methods, manufacturers would have to apply to us and demonstrate
equivalence. Examples of alternative approaches that we anticipate manufacturers may use are
the recirculation technique described in SAE J1737,189 enclosure-type testing such as in 40 CFR
part 86, or weight loss testing such as described in SAE J1527.190
Coast Guard standards for marine fuel hoses (33 CFR part 183) cite SAE recommended
practice J1527191 which, among other things, includes test procedures for measuring permeation
from marine fuel hoses. In this test procedure, a short section of hose is attached to a
nonpermeable container (i.e. metal fuel can) and plugged. Fuel is added to the container and the
mass of the entire unit is measured every 24 hours for 15 days and the peak fuel loss is
determined. This testing is performed at 23 ± 2°C on both reference fuel "C" for the version of
the SAE standard referenced in 33 CFR part 183. However, SAE J1527 was revised in 1993 to
include permeation standards for hoses tested on a fuel blend with 15 percent methanol. This
test procedure is simple; however, it is sufficient for marine hoses because they have high
permeation rates ranging from 100 to 600 g/m2/day depending on the hose class and the fuel
used.
Recommended practice for automotive fuel tubing is defined in SAE J2260.192 The
permeation requirements in this standard are one to two orders of magnitude lower than those
defined for marine hoses. These permeation requirements are based on the same fuels as the
revised SAE J 1527, but at a much higher temperature (60°C). At 60°C, permeation rates for a
5-89
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Draft Regulatory Impact Analysis
given material may be 16 times as high or higher than at 23 °C based on the rule of thumb that
permeation doubles for every 10°C increase in temperature. SAE J2260 refers to the permeation
test procedures in SAE J1737.193
The procedures in SAE J1737 were designed to measure the low permeation rates needed
in automotive applications to meet EPA evaporative emission requirements. There was concern
that the weight loss measurement, such as used in SAE J1527, was not sensitive enough to
measure these low permeation rates. In addition, this procedure requires exposing the material to
be tested for hundreds of hours, depending on the material and fuel, to reach a steady-state
permeation rate. In this procedure, fuel is heated to 60°C and circulated through a tube running
through a glass test cell. Nitrogen around the tube in this test cell is used to carry the permeate
to activated charcoal canisters. The canisters are weighed to determine their capture. Because
the canister is much lighter than the reservoir/hose in the SAE J1527 configuration, a much more
accurate measurement of the permeation loss can be made.
Some manufacturers of low permeability product are finding that as their emission rates
decrease, they need more refined test procedures to accurately measure permeation. These
manufacturers are finding that the weight of the charcoal canisters are much higher than the
permeate being measured. As an alternative to the gravimetric approach used in the above two
procedures, even very low permeation emissions can be measured by a flame ionization detector
and a SHED. As discussed earlier, SHED testing is generally used to measure evaporative
emissions from whole automobile systems as well.
5.6.2 Fuel Tank Permeation Testing
We are proposing to apply a similar fuel tank permeation test procedures to Small SI
equipment and Marine SI vessels as we currently use for recreational vehicles. This testing
includes preconditioning, durability testing, and permeation measurement. The proposed
differences in the test procedure compared to recreational vehicles are minor and are intended to
simplify the testing. For instance, the durability testing would be performed during the
preconditioning soak period prior to the weight loss testing rather than testing the tank twice;
once before durability testing, and once after. Figure 5.6-2 provides flow charts for this testing
compared to the recreational vehicle test which includes the calculation of a deterioration factor.
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Feasibility of Evaporative Emission Control
Figure 5.6-2: Flow Chart of Fuel Tank Permeation Test with and without a
Deterioration Factor (DF) Determination
1: Full Test Procedure
with DF* Determination
2: Short Test without
DF Determination
baseline
permeation test run
ElOfuel
28 ±2 C
I
1
1
I
Durability Testing
Pressure Cycling I
1 0,000 x -0.5 to 2.0 psi !
UV Exposure
24W/m2
Slosh Testing
1 million cycles
ElOfuel
Durability Testing
Pressure Cvclina
10,000 x-0.5 to 2.0 psi
UV Exposure
24W/m
Slosh Testing
1 million cycles
ElOfuel
final
permeation test run
ElOfuel
28±2C
final
permeation test run
ElOfuel
28 ±2 C
use final permeation
test result for
certification
use final permeation
test result for
certification
* The deterioration factor (DF) is the difference
between the baseline and final permeation test
runs in the full test procedure. In future tests, the
first 3 steps would be performed, then a DF could
be applied to determine the final test result.
** The length of "soak" during durability testing
may be included in the fuel soak period provided
that fuel remains in the tank. Soak periods can be
shortened to 10 weeks if performed at 43 ± 5 C
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Draft Regulatory Impact Analysis
For the purpose of this testing, "fuel tank" includes the fuel cap and other components
directly mounted to the tank that become part of the barrier for the fuel and vapor. During
testing, fittings and openings in the fuel tank intended for hose connections (or petcock) would
be sealed with an impermeable plug. An opening containing a fuel petcock could also be
plugged with an impermeable fitting because this is an opening to the fuel hose which will be
required to meet permeation standards. In many installed marine fuel tanks, the fuel cap is not
directly mounted on the fuel tank. Instead, the fuel cap is usually linked to the fuel tank by a fill
neck hose. In this case, the fill neck opening in the fuel tank may be sealed with an impermeable
plug during permeation testing.
5.6.2.1 Durability Testing
Prior to the weight loss test, the fuel tank must be preconditioned to ensure that the
hydrocarbon permeation rate has stabilized. Under this step, the fuel tank must be filled with a
10 percent ethanol blend (E10), sealed, and soaked for 20 weeks at a temperature of 28 °C ± 5
°C. Once the permeation rate has stabilized, the fuel tank is drained and refilled with E10,
sealed, and tested for a baseline permeation rate. The permeation rate from the fuel tank is
determined by measuring the weight difference the fuel tank before and after soaking at a
temperature of 28 °C ± 2 °C over a period of at least 20 weeks. The soak periods could be
shortened to 10 weeks if performed at 43 °C ± 5 °C. The durability testing described below may
be performed during the soak period. During the slosh testing, a lower tank fill level, consistent
with the proposed slosh test, would be acceptable.
To determine a permeation emission deterioration factor, we are proposing three
durability tests: slosh testing, pressure-vacuum cycling, and ultra-violet (UV) light exposure.
The purpose of these deterioration tests is to help ensure that the technology is durable and the
measured emissions are representative of in-use permeation rates. For slosh testing, the fuel tank
is filled to 40 percent capacity with E10 fuel and rocked for 1 million cycles. The pressure-
vacuum testing contains 10,000 cycles from -0.5 to 2.0 psi. The slosh testing is designed to
assess treatment durability as discussed above. These tests are designed to assess surface
microcracking concerns. These two durability tests are based on a draft recommended SAE
practice.194 The third durability test is intended to assess potential impacts of UV sunlight (0.2
|im - 0.4 |im) on the durability of the surface treatment. In this test, the tank must be exposed to
a UV light of at least 0.40 W-hr/m2 /min on the tank surface for 15 hours per day for 30 days.
Alternatively, it can be exposed to direct natural sunlight for an equivalent period of time in
exposure hours.
The order of the durability tests is optional. However, we require that the fuel tank be
soaked to ensure that the permeation rate is stabilized just prior to the weight loss test. If the
slosh test is run last, the length of the slosh test may be considered as part of this soak period.
Where possible, the deterioration tests may be run concurrently. For example, the fuel tank
could be exposed to UV light during the slosh test. In addition, if a durability test can clearly be
shown to not be appropriate for a given product, manufacturers may petition to have this test
waived. For example, a fuel tank that is only used in vehicles where an outer shell prevents the
tank from being exposed to sunlight may not benefit from UV testing.
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Feasibility of Evaporative Emission Control
After the durability testing, once the permeation rate has stabilized, the fuel tank is
drained and refilled with fresh fuel, sealed, and tested for a final permeation rate. The final
permeation rate from the fuel tank is determined using the same measurement method as for the
baseline permeation rate. The final permeation rate would be used for the emission rate from
this fuel tank. The difference between the baseline and final permeation rates could be used to
determine a deterioration factor for use on subsequent testing of similar fuel tanks.
5.6.2.2 Test Fuel
As discussed in Chapter 3, about 30 percent of fuel sold in the U.S. contains ethanol and
this percentage is expected to increase to about 45-50 percent in 2012 and later. We are
proposing the use of E10, which is a blend of 90 percent certification gasoline (as specified in 40
CFR 1065.210) blended with 10 percent ethanol for permeation testing of fuel tanks. As an
alternative, we are proposing that ASTM Fuel C blended with 10 percent ethanol (Fuel CE10)
may be used. Fuel CE10 is commonly used in industry standards and test procedures such as in
SAE recommended practices.
5.6.2.2.1 Effect of ethanol on fuel tank permeation
Most plastic nonroad fuel tanks today are made out of high-density polyethylene (HDPE)
or cross-link polyethylene (XLPE). For Small SI and Marine SI markets, plastic is much more
widely used than metal for fuel tank constructions. For HDPE, E10 fuel has little effect on
permeation emissions and may even result in slightly lower emissions according to one study.195
We tested three 0.5 gallon Small SI fuel tanks for permeation using both certification gasoline
and E10 and found a slight increase in permeation due to ethanol. ARB also tested several Small
SI fuel tanks on both gasoline and ethanol blends 196>197>198>199 ancj saw a small increase in
permeation. Permeation data was collected on two XLPE marine fuel tanks on E10. The
measured permeation rates were within the range of data from other XLPE marine fuel tanks
tested on gasoline presented earlier in Table 5.3-1. This data is presented in Table 5.6-1.
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Draft Regulatory Impact Analysis
Table 5.6-1: Effect of Ethanol on Permeation for HDPE Fuel Tanks
Material
HDPE
HDPE
HDPE
XLPE
Test Equipment
material sample
Small SI fuel
tanks
(EPA Testing)
Small SI fuel
tanks
(ARE Testing)
marine tanks
(EPA testing)
Tank
gallons
NA
0.5
0.5
0.5
0.25
0.25
0.25
0.25
0.25
0.5
3.9
12
12
Test
Temp(s)
40°C
29°C
18-41T
29°C
gasoline
|g/m2/day]
90*
11.5
11.4
11.2
11.6
10.7
12.5
9.9
9.2
12.7
4.8
**
E10
[g/m2/day]
69*
13.9
13.7
14.4
13.6
11.6
11.4
10.3
10.3
14.8
5.0
7.5
8.5
Increase in
Permeation
-23%
21%
21%
28%
18%
7%
-9%
4%
12%
17%
4%
minimal
*ASTM Fuel C was used as gasoline (50% toluene, 50% isooctane). Units are per mm of
thickness
** See Table 5.3-1 for data on similar tanks tested on gasoline.
Although E10 does not have a large effect on permeation through polyethylene, it does
have a large effect on most other materials used in fuel systems, especially those designed for
low permeation. This is supported by the data presented in Appendix 5D of permeation rates for
several fuel system materials on fuel C, CE10, and CIS. In addition, ethanol is commonly
blended into fuels in-use and alcohol fuels may be used more in the future in an effort to use
alternative energy sources. Therefore, we are proposing El0 as a test fuel to ensure that the
proposed permeation standard will be met on in-use fuels.
A recent study found that permeation from automotive fuel systems increased
significantly when gasoline containing ethanol was used compared to gasoline without
ethanol.200 In this case the ethanol fuel was specifically blended to achieve two weight percent
oxygen. This test fuel represents California reformulated fuel and contains 5.7 percent by
volume ethanol. Table 5.6-2 presents the test results at 29°C. The average increase in
permeation due to using E5.7 was 60 percent. Presumably, this effect would have been higher
on E10. Because most of the fuel tanks are metal, the effect is largely due to fuel hose/tubing
permeation. The highest effect of ethanol in gasoline on permeation probably occurs when 10-
30 percent ethanol is blended into the gasoline. We are just beginning a contract for testing to
study permeation rates at various ethanol fuel blends as part of our on-highway inventory
modeling efforts.
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Table 5.6-2: Effect of Ethanol on Permeation from Automotive Fuel Systems
Fuel System
2001 Toyota Tacoma
2000 Honda Odyssey
1999 Toyota Corolla
1997 Chrysler Town & Country
1995 Ford Ranger
1993 Chevrolet Caprice Classic
1991 Honda Accord LX
1989 Ford Taurus GL
1985 Nissan Sentra
1978 Olds Cutlass Supreme
Fuel Tank
Metal
Plastic (enhanced evap)
Metal
Plastic (enhanced evap)
HOPE
Fluorinated HOPE
Metal
Metal
Metal
Metal
Gasoline
10
19
11
40
348
94
39
28
73
73
E5.7
32
53
57
66
342
137
100
73
177
139
Increase
220%
179%
418%
65%
-2%
46%
156%
161%
142%
90%
One significant finding with the above study was that switching from one fuel to another
affects the permeation rate within a few weeks. Although operating on gasoline with ethanol
changes the fuel tank material in such a way that permeation increases, this effect is reversible
when gasoline is used in the fuel tank for a long enough period of time. This study found that
the permeation rate at 40°C typically approached a stabilized level within 1 to 2 weeks of
switching from one fuel to another.
To investigate the potential effects of fuel switching, we tested two pairs of 6.6 gallon
portable marine fuel tanks. These fuel tanks used the barrier platelet technology discussed
above. The first pair used nylon as a barrier material which is highly sensitive to ethanol while
the second pair used EVOH which is much less sensitive to ethanol. All four tanks were soaked
on E10 fuel, then the fuel was drained and replaced for testing. For each pair, one tank was
tested on EPA certification gasoline and the other was tested on E10 fuel (10 percent ethanol, 90
percent gasoline). We continued the test for more than six weeks to observe the effects of fuel
switching on the permeation rates. The results suggest that switching to gasoline significantly
reduces the permeation rate for the nylon barrier tanks, but has no significant effect on the fuel
tanks using EVOH as a barrier. Note that the nylon tanks had permeation rates near the
proposed standards when soaked and tested on gasoline, but have much higher permeation rates
when tested on E10. This data is presented in Figure 5.6-1. The R-squared values for linear fits
to the data are also presented. The fuel tank with a nylon barrier that experienced fuel switching
had a lower R-squared value than the other fuel tanks.
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Figure 5.6-1: Effect of Fuel Switching on Permeation from Barrier Platelet Fuel Tanks
Nylon, Gasoline
Nylon, E10
EVOH, Gasoline
EVOH, E10
Fuel tank permeation data on both gasoline and E10 fuel were presented earlier in this
chapter for nylon handheld tanks, fluorinated and sulfonated Small SI tanks, portable tanks with
non-continuous nylon barrier platelets, and rotationally molded tanks with a nylon inner barrier.
This data is repeated here in Table 5.6-3 to better focus on the effect of ethanol on fuel tank
permeation. As shown by this data and the previous discussion, ethanol in the test fuel tends to
increase permeation. However, the effect of ethanol on permeation appears to be highly variable
depending on the materials or surface treatments used in constructing the fuel tank.
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Table 5.6-3: Permeation Rates on Gasoline and E10 for Barrier Fuel Tanks
Permeation Control
nylon 6
nylon 6, 33% glass
nylon 6, 30% glass
nylon 6, 30% glass
fluorination
sulfonation
non-continuous nylon platelets
Rotomolded with PA1 1 liner*
Capacity
[gallons]
0.24
0.05
0.06
0.06
0.5
0.5
2.0
1mm barrier
thickness
Gasoline
[g/m2/day]
0.34
0.62
1.45
1.30
0.56
0.62
0.22
2.5
2.7
2.2
3.7
0.17
0.24
0.12
E10
[g/m2/day]
0.42
0.48
1.01
1.12
0.93
2.2
2.5
1.4
2.1
0.43
0.62
0.62
3.9
4.2
2.9
6.8
0.91
0.72
0.78
0.81
% Increase
32%
65%
60%
37%
19%
49%
84%
350%
based on testing for California (California Phase II gasoline and fuel CE10)
5.6.2.2.2 Effect ofCElO versus E10 on fuel tank permeation
As discussed above, we are proposing to allow the use of fuel CE10 as an alternative to
E10 for fuel tank permeation testing. The primary fuel, E10 is representative of in-use fuel and
is consistent with the certification fuel used for recreational vehicles. However, fuel CE10 is
widely used by industry for materials testing. Data presented earlier in this chapter suggests that
permeation is generally significantly higher on fuel CE10 for fuel hoses. We were therefore
interested in the effect of fuel CE10 versus E10 on fuel tank permeation. We tested several fuel
tanks and found that permeation was only slightly higher on CE10 than E10 for most of the fuel
tanks tested.
To study the effects of CE10 versus E10 on permeation, we used fuel tanks that had been
previously tested on fuel E10. All of these tanks were drained and refueled with fresh test fuel.
Most of the tanks were filled with fuel CE10; however, with some exceptions, one of each tank
type was filled with fresh E10 for comparison. These fuel tanks were then preconditioned by
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soaking them for 12 weeks with the new test fuel. Note that all of the test tanks had been
soaking with E10 fuel for more than a year (and in some cases multiple years) prior to beginning
this preconditioning soak. Following the soak period, each tank was drained, refilled with fresh
fuel, and sealed. Permeation was measured over two weeks at 29°C. The fuel tanks were
weighed on each weekday during this period.
Table 5.6-4 presents the results of this testing. In most cases, emissions were only
slightly higher on CE10 than E10. The exceptions were the nylon 6 and the acetal copolymer
fuel tanks which showed much higher permeation on CE10. However, the permeation rates for
these fuel tanks were still below the proposed standard when tested on fuel CE10. The fuel tank
with a continuous EVOH barrier was well below the proposed standard on fuel CE10. No
comparison was made to E10 results for this technology.
Table 5.6-4: Permeation Rates on Gasoline and E10 for Barrier Fuel Tanks
Permeation Control
nylon 6
HOPE
fluorination
sulfonation
non-continuous platelets (4% nylon)
non-continuous platelets (2% EVOH)
non-continuous platelets (4% EVOH)
non-continuous platelets (6% EVOH)
continuous EVOH barrier
acetal copolymer
Capacity
[gallons]
0.24
0.5
0.5
0.5
6.6
6.6
6.6
6.6
5.6
0.8
E10
[g/m2/day]
0.69
12.5
0.41
3.1
4.5
3.0*
2.2
1.3
~
0.25
CE10
[g/m2/day]
1.4
1.2
13.3
13.5
0.49
0.52
4.2
2.9
5.3
3.3
2.3
1.4
0.05
0.01
0.55
0.65
% Increase
90%
7%
21%
16%
16%
10%
6%
6%
NA
140%
based on previous testing (presented earlier in this chapter)
5.6.2.3 Reference Tank
In cases where the permeation of a fuel tank is low, and the sample tank is properly
sealed, the effect of air buoyancy can have a significant effect the measured weight loss. Air
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buoyancy refers to the effect on air density on the perceived weight of an object. As air density
increases, it will provide an upward thrust on the fuel tank and create the appearance of a lighter
tank. Air density can be determined by measuring relative humidity, air temperature, and air
pressure.201
One testing laboratory presented data to EPA on their experience with variability in
weight loss measurements when performing permeation testing on portable fuel tanks.202 They
found that the variation was due to air buoyancy effects. By applying correction factors for air
buoyancy, they were able to greatly remove the variation in the test data. A technical brief on
the calculations they used is available in the docket.203
A more direct approach to accounting for the effects of air buoyancy is to use a reference
fuel tank. In this approach, an identical fuel tank to that being tested for permeation would be
tested without fuel in it and used as a reference fuel tank. Dry sand would be added to this tank
to make up the difference in mass associated with the test tank being full of fuel. The reference
tank would then be sealed so that the buoyancy effect on the reference tank would be the same as
the test tank. The measured weight loss of the test tank could then be corrected by any measured
changes in weight in the reference tank. The California Air Resources Board has proposed this
approach for measuring portable fuel tank emissions, and they refer to the reference tank as a
"trip blank."204
5.6.2.4 Engineering Design-Based Certification
Fuel does not permeate through metal and automotive style EVOH barrier tanks have
very low permeation through the walls of the tank. We are proposing to allow design-based
certification for metal tanks and co-extruded high-density polyethylene fuel tanks with a
continuous ethylene vinyl alcohol barrier layer. The EVOH barrier layer would be required to be
at least 2 percent of the wall thickness of the fuel tank.
To address the permeability of the fuel cap, seals, and gaskets used on metal and
co-extruded tanks, we are proposing that the design criteria include a specification that seals and
gaskets that are not made of low-permeation materials must have a total exposed surface area
less than 1000 mm2. A low-permeation material would have a permeation rate not more than 10
g-mm/m2/day at 23°C on CE10 fuel as tested under the procedures specified in SAE J2659.205 A
metal or co-extruded fuel tank with seals that meet this design criterion would reliably pass the
standard.
5.6.3 Diurnal Emission Testing
The proposed test procedure for diurnal emissions is to place the fuel tank in a SHED6,
vary the temperature over a prescribed profile, and measure the hydrocarbons escaping from the
fuel tank. The final result would be reported in grams per gallon where the grams are the mass
6 Sealed Housing for Emission Determination
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of hydrocarbons escaping from the fuel tank over 24 hours and the gallons are the nominal fuel
tank capacity. The proposed test procedure is based on the automotive evaporative emission test
described in 40 CFR part 86, subpart B, with modifications specific to marine applications. If
we were proposing diurnal emissions standards for Small SI applications, the test procedures
would be similar and would be based on a 72-96°F temperature profile.
5.6.3.1 Temperature Profile
We are proposing that portable marine fuel tanks would be tested over the same 72-96°F
(22.2-35.6°C) temperature profile used for automotive applications. This temperature profile
represents a hot summer day when ground level ozone emissions (formed from hydrocarbons
and oxides of nitrogen) would be highest. This temperature profile would be for the air
temperature in the SHED.
For installed marine fuel tanks, we believe that the fuel temperature profile observed in
the tank would have a lower variation in temperature due to the inherent insulation provided by
the boat hull. Data discussed earlier in this chapter, and presented in Appendix 5A, suggest that
the fuel temperature in an installed marine tank would see a change in temperature less than that
of ambient air. Based on this data, the fuel temperature change in boats stored on trailers would
be expected to be about half of ambient. For boats stored in the water, the fuel temperature
change would be expected to be about 20 percent of ambient. Based on discussions with
industry, we use a boat length as a surrogate for determining if a boat is a trailer boat. We are
proposing to consider a boat below 26 feet (7.9 m) in length as a trailer boat and larger boats as
being primarily stored in the water.
To account for the differences between ambient and fuel temperature, we are proposing a
test temperature profile of 78-90°F (25.6-32.2°C) for marine fuel tanks installed in boats less
than 26 feet in length. For larger boats, we are proposing a test temperature profile of 81.6-
86.4°F (27.6-30.2°C). These test temperature profiles would be based on fuel rather than
ambient temperature. Figure 5.6-3 presents the three temperature profiles over 24 hours.
Numerical values are presented in Appendix 5E.
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Feasibility of Evaporative Emission Control
Figure 5.6-3: Proposed Diurnal Temperature Profiles
'portable (air temp)
- - - installed <26ft (fuel temp)
— - installed >26ft (fuel temp)
70
8 12 16
Elapsed Time [hours]
20
24
The automotive diurnal test procedure includes a three day temperature cycle. The
purpose of this test length is to ensure that the carbon canister can hold at least three days of
diurnal emissions without vapor breaking-through the canister. For vessels using carbon
canisters as an evaporative emission control strategy, we are proposing a multiple day cycle here
as well so that the passive purging can be observed. In the automotive test, the canister is
loaded, then purged during an engine test prior to the first day of testing. Because we are
anticipating canisters on marine applications to be passively purged we are proposing a different
approach. Prior to the first day of testing, the canister would be loaded to full working capacity,
then run over the diurnal test temperature cycle to allow one day of passive purging. The test
result would then be based on the highest recorded value in the following three days.
For fuel systems using a sealed system (or sealed-system with pressure relief), we do not
believe that a three day test would be necessary. Prior to the first day of testing, the fuel would
be stabilized at the initial test temperature. Following this stabilization, the SHED would be
purged and a single diurnal temperature cycle run. Because this technology does not depend on
purging or storage capacity of a canister, multiple days of testing should not be necessary.
Therefore, we are proposing a one-day test for the following technologies: sealed system without
pressure relief, sealed system with a pressure relief valve, sealed bladder fuel tanks, sealed fuel
tanks with a volume compensating air bag.
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5.6.3.2 Test Fuel
Consistent with the automotive test procedures, we are proposing that the test take place
using certification gasoline with a vapor pressure of 9.0 RVP. We are not proposing to require
ethanol to be blended into the test fuel. Although ethanol has a significant effect on permeation,
it would not be expected to affect diurnal emissions except in that it may affect fuel vapor
pressure.
Diurnal emissions are not only a function of temperature and fuel volatility, but of the
size of the vapor space in the fuel tank as well. Consistent with the automotive procedures, we
are proposing that the fill level at the start of the test be 40 percent of the nominal capacity of the
fuel tank. Nominal capacity of the fuel tank would be defined as the volume of fuel, specified by
the manufacturer, to which the fuel tank can be filled when sitting in its intended position. The
vapor space that normally occurs in a fuel tank, even when "full," would not be considered in the
nominal capacity of the fuel tank.
5.6.3.3 Tank Configuration
Personal watercraft and other installed marine fuel tanks are typically equipped with a
vent line. As shown above, this vent line can impact the emissions determined over the test
procedure because it largely restricts diffusion losses. Therefore, for open vent marine fuel tanks
that are designed with a connection for a vent line, we propose that the be equipped with a one
meter fuel line to more accurately reflect real world emissions. This should only be necessary
for baseline configurations.
The majority of marine fuel tanks are made of plastic. Even plastic fuel tanks designed to
meet our proposed standards would be expected to have some amount of permeation. However,
over the length of the diurnal test, if it were performed on a new tank that had not been
previously exposed to fuel, the effect of permeation on the test results should be insignificant.
For fuel tanks that have reached their stabilized permeation rate (such as testing on in-use tanks),
we believe that it would be appropriate to correct for permeation. In such a case, we propose
that the permeation rate could be measured from the fuel tank and subtracted from the final
diurnal test result. The fuel tank permeation rate would have to be stabilized on the 9 RVP test
fuel used for the diurnal test and measured either over the diurnal temperature cycle or at a
constant temperature (28 ± 2°C). This test measurement would have to be made just prior
(within 24 hours) to the diurnal emission test to ensure that the permeation rate does not change
prior to the diurnal test. In addition, the test fuel would need to remain in the fuel tank between
the permeation and diurnal tests to ensure a stable permeation rate. The fuel tank could be
emptied to change test fuels and test set ups; however, this period would not be allowed to
exceed one hour. As an alternative to stabilizing the permeation rate prior to testing, the
permeation could be measured immediately before and after the diurnal test, and the lower
permeation rate used to correct the diurnal test results. In this case, the test fuel would not be
removed after the diurnal test, and the second permeation test would begin within 8 hours of the
end of the diurnal test.
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5.6.3.4 Carbon Canister Engineering Design
We are proposing to allow design-based certification as an option to performing the
above test. For vessels using a carbon canister to control diurnal emissions, it is important to
ensure that the canister design is sufficient to achieve the proposed standards. The following
discussion outlines the requirements that would be necessary to ensure adequate canister design.
These design parameters and their associated test procedures are largely based on our
understanding of current industry practices for marine grade carbon.206
5.6.3.4.1 Carbon canister capacity
In a passive purge system, the storage capacity of the carbon canister must be properly
matched to the fuel system. Ideally, the canister would be large enough to take full advantage of
the passive purge caused by cooling of the fuel tank. By creating more open sites in the canister,
greater vapor collection is possible during the next heating event. If a canister is undersized,
then the vessel would not likely meet the proposed standards. On the other hand, after a certain
point, increasing the size of the canister offers little additional emission control. Once the
system reaches a stabilized purge/load condition, the emission reduction potential is based on the
portion of the canister that purges and loads rather than the full volume of the canister.
The storage capacity of a carbon canister is based both on the volume of the canister and
the working capacity of the carbon. Butane working capacity (BWC) is a measure of the vapor
storage capacity of the carbon and is expressed in units of mass of butane per unit of volume.
We are proposing that the BWC of the carbon be at least 9 g/dL based on the test procedures
specified in ASTM D5228-92.207 Under this test procedure, butane vapor is fed through a
carbon sample at a specified rate, until the mass of the carbon sample reaches equilibrium. The
butane is then purged off with dry air. BWC of the carbon sample is calculated from the
difference in the measured mass of the carbon sample before and after the purge.
Using the ASTM test procedure, the BWC represents the full saturated capacity of the
canister and not the amount of vapor that the canister will hold before breakthrough occurs.
Under the EPA automotive test procedure in 40 CFR 86.134-96, the canister capacity is based on
the amount of butane loaded in the canister until 2 grams of breakthrough is measured.
However, we are proposing to use the ASTM procedure because it gives a repeatable measure
that is currently used by industry. The design standard of 9 g/dL is based on this test procedure
and therefore accounts for the differences in the ASTM and existing EPA automotive procedure.
Based on the data presented earlier in this chapter, we are proposing that the volume of
the carbon canister must be a minimum of 0.04 liters of carbon per gallon of fuel tank capacity
for fuel tanks installed in boats less than 26 feet in length. For larger boats, the fuel temperature
may be less affected by diurnal temperature swings for two reasons. First, these fuel tanks
would be in larger vessels which are more likely to be stored in the water and therefore, subject
to smaller temperature fluctuations. Second, these fuel tanks would likely be larger and have
larger thermal inertia in the fuel which may lead to lower temperature fluctuation. Therefore, for
fuel tanks installed on boats greater than or equal to 25 feet, we are proposing a design minimum
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volume of 0.016 liters of carbon every gallon per gallon of fuel tank capacity.
5.6.3.4.2 Carbon humidity resistance
In a marine environment, the carbon may be exposed to more humid air, on average, than
in land-based applications such as cars and trucks. Traditional carbons used in automotive
applications can adsorb water, thereby closing sites off to hydrocarbons. With active purge and
carbon heating during refueling vapor collection, the water vapor is easily purged off the carbon.
Under this proposed rule, we are basing the design specification on a passive purge canister
design and are not requiring onboard refueling vapor recovery. Therefore, we believe that the
carbon should be resistant to moisture in the air. In the in-use program discussed above, marine
grade carbon was used that was developed specifically for high humidity applications.208
We proposing design-based certification requirements for humidity resistance based on
the specifications of the humidity-resistant carbon used in the in-use demonstration program.
This carbon meets a moisture adsorption capacity maximum of 0.5 grams of water per gram of
carbon at 90 percent relative humidity and a temperature of 25±5°C. This limit is based on a test
procedure where dried carbon is exposed to water vapor and the pressure in the sample chamber
is controlled to achieve the correct partial pressure of the water to achieve the desired relative
humidity. The adsorption of water in the carbon is calculated based on the reduction in pressure
in the sample chamber. More detail on this test procedure is available in the docket.209
5.6.3.4.3 Carbon durability
Another issue that has been raised with regard to canister use in marine applications is
the durability of the canister under the shocks that can be observed on a marine vessel.
Automotive applications see shocks and vibration as well and the carbon is protected by packing
it under pressure in the canister. To address the concern of carbon durability, however, we are
proposing to include a carbon strength requirement. This strength requirement is consistent with
the specifications for the carbon used in the in-use test program described above, which was
designed to have a higher hardness value and lower dust attrition rates than typical automotive
carbons.
The industry procedure for carbon pellet strength is to determine the average pellet size
in a sample of carbon before and after a pan hardness test. Pellet size is determined by
separating the carbon by size using sieves. The pan hardness test involves shaking the carbon in
a pan with steel balls over a fixed period of time. The pellet strength is determined by taking the
ratio of the average pellet size of the carbon before and after the pan and ball attrition test. We
are proposing a pellet strength of at least 85 percent. The proposed test procedure is ASTM
D3802-79210 with two variations. First, as discussed above, hardness is defined as the ratio of
mean particle diameter before and after the attrition test. Second, the attrition test would use
twenty 1/2M steel balls and ten 3A" steel balls rather than fifteen of each as specified in ASTM
D3802-79. These proposed variations on the ASTM procedure reflect common industry practice
for pelletized carbons in contrast to the original test procedure which were intended for granular
carbons.211
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5.6.3.4.4 Canister design
The design of the canister itself is important in building an effective and durable carbon
canister system. The canister should be made of a material that is compatible with the
application. For instance, the material should be fuel resistant and durable. Where a flame test
is required by the Coast Guard, the material should be able to pass this test on its own or with a
protective cover. In addition, the canister material must have good structural integrity at
temperatures that it would be exposed to in a boat. If the material changes in dimension at
temperature, that flexing may loosen the carbon packing, allowing the carbon to move and
eventually deteriorate. The canister should be installed in the boat in such a way that undue
stress is not placed on the canister. It should also be properly constructed so that there are no
leaks in the canister.
The canister must be packed in such a way that the carbon does not move inside the
canister in-use. If the carbon were able to move, it would eventually break down under
vibration. Over time the carbon could deteriorate into dust which could eventually escape from
the canister. This is not an issue with a carbon canister that uses a properly designed and
installed volume compensator. The basic design of a volume compensator is that compression is
held on the carbon bed with a spring. A mesh or foam cover is used on the volume compensator
that will allow air to pass through, but will hold the carbon pellets in place.
The carbon should be packed into the canister in such a way that there is a consistent size
of carbon pellets throughout the canister. If the carbon settles in the storage hopper, it would be
possible for some canisters to be filled largely with the smallest diameter carbon pellets (or dust)
which would increase the pressure restriction of the canister. Also, if the carbon is not packed
properly when placed into the canister, it could later settle leading to a volume reduction of the
carbon that is too large for the volume compensator to address.
The carbon canister design must allow for a proper flow path of vapor and air through the
carbon bed. In current carbon canister designs, an air gap is typically installed upstream of the
carbon bed. Flow directors may be molded into this air gap. The purpose of the air gap is to
allow the vapor or purge air to disperse and flow through the entire carbon bed. Even with a
small air gap, the vapor will disperse because it will attempt to follow the path of least resistance
through the canister. Without the air gap, the flow could be predominately in the center of the
carbon (or wherever the intake hose connection is located).
The geometry of a carbon canister can affect the effectiveness of the control system. For
instance, a long, narrow canister will have higher efficiency than a short wide canister. This is
because some breakthrough can occur if the pathway is too short for the flow of vapor. Based on
one study, the effectiveness of the carbon canister increases notably until a length to diameter
ratio of about 3.5 is achieved.212 At higher ratios, less of an impact on efficiency was observed.
At too high of a length to diameter ratio, significant back pressure may occur in the system.
5.6.3.4.5 Integration with Fuel System
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It would be important that a carbon canister system be appropriately integrated into the
fuel system. For instance, the canister would need to be positioned in the vent line, and
potentially a liquid separation valve added, to ensure that liquid fuel would not reach the canister
during refueling. We would also expect the fuel system design to minimize spit-back out of the
fill neck during refueling. A design that caused fuel to stream out the fill neck during refueling,
even with a fuel nozzle shut-off mechanism, would not be acceptable.
5.7 Impacts on Noise, Energy, and Safety
The Clean Air Act requires EPA to consider potential impacts on noise, energy, and
safety when establishing the feasibility of new emission standards for marine vessels.
5.7.1 Noise
In this case, we would not expect evaporative emission controls to have any impact on
noise from Small SI equipment or marine vessels because noise from the affected parts of the
fuel system is insignificant.
5.7.2 Energy
We anticipate that the proposed evaporative emission standards will have a positive
impact on energy. By capturing or preventing the loss of fuel through evaporation, we estimate
that the lifetime average fuel savings would be about 1.2 gallons for an average piece of Small SI
equipment and 31 gallons for an average boat. This translates to a fuel savings of about 44
million gallons for Small SI equipment and 26 million gallons for Marine SI vessels in 2030
when most of the affected equipment used in the U.S. would be expected to have evaporative
emission control.
5.7.3 Safety
As part of the development of this proposed rule, EPA performed a technical study on the
safety of emission control technology for Small SI equipment and Marine SI vessels.213 The
conclusions of this study are presented below. Although the study focuses on equipment with
engines less than 37 kilowatts, the conclusions drawn for marine apply to boats with larger
engines as well as ABYC, USCG, UL, and SAE requirements do not distinguish between engine
sizes.
EPA has reviewed the fuel hose and fuel tank characteristics for NHH and HH equipment
and evaluated control technology which could be used to reduce evaporative emissions from
these two subcategories. This technology is capable of achieving reductions in fuel tank and fuel
hose permeation without an adverse incremental impact on safety. For fuel hoses and fuel tanks,
the applicable consensus standards, manufacturer specific test procedures and EPA requirements
are sufficient to ensure that there will be no increase in the types of fuel leaks that lead to fire
and burn risk in use. Instead, these standards will reduce vapor emissions both during operation
and in storage. That reduction, coupled with some expected equipment redesign, is expected to
5-106
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Feasibility of Evaporative Emission Control
lead to reductions in the risk of fire or burn without affecting component durability.
We also conducted a design and process Failure Mode and Effects Analyses (FMEA)
comparing current Phase 2 and Phase 3 compliant engines and equipment to evaluate
incremental changes in risk probability as a way of evaluating the incremental risk of upgrading
Phase 2 engines to meet Phase 3 emission standards.214 This is an engineering analysis tool to
help engineers and other professional staff on the FMEA team to identify and manage risk. In a
FMEA, potential failure modes, causes of failure, and failure effects are identified and a
resulting risk probability is calculated from these results. This risk probability is used by the
FMEA team to rank problems for potential action to reduce or eliminate the causal factors.
Identifying these causal factors is important because they are the elements that a manufacturer
can consider reducing the adverse effects that might result from a particular failure mode.
Our FEMA evaluated permeation and running loss controls on nonhandheld engines. We
found that these controls would not increase the probability of fire and burn risk from those
expected with current fuel systems, but could in fact lead to directionally improved systems from
a safety perspective. Finally, the running loss control program being proposed for nonhandheld
equipment will lead to changes that are expected to reduce risk of fire during in-use operation.
Moving fuel tanks away from heat sources, improving cap designs to limit leakage on tip over,
and requiring a tethered cap will all help to eliminate conditions which lead to in-use problems
related to fuel leaks and spillage. Therefore, we believe that the application of emission control
technology to reduce evaporative emissions from these fuel hoses and fuel tanks will not lead to
an increase in incremental risk of fires or burns and in some cases is likely to at least
directionally reduce such risks.
EPA has reviewed the fuel hose and fuel tank characteristics for marine vessels and
evaluated control technology which could be used to reduce evaporative emissions from boats.
With regard to fuel hoses, fuel tanks, and diurnal controls, there are rigorous USCG, ABYC, UL,
and SAE standards which manufacturers will continue to meet for fuel system components. All
of these standards are designed to address the in-use performance of fuel systems, with the goal
of eliminating fuel leaks. The low permeation fuel hoses and tanks needed to meet the Phase 3
requirements would need to pass these standards and every indication is that they would pass.
Furthermore, the EPA permeation certification requirements related to emissions
durability will add an additional layer of assurance. Low permeation fuel hoses are used safely
today in many marine vessels. Low permeation fuel tanks and diurnal emission controls have
been demonstrated in various applications for many years without an increase in safety risk.
Furthermore, a properly designed fuel system with fuel tank and fuel hose permeation controls
and diurnal emission controls would reduce the fuel vapor in the boat, thereby reducing the
opportunities for fuel related fires. In addition, using improved low permeation materials
coupled with designs meeting USCG and ABYC requirements should reduce the risk of fuel
leaks into the vessel. EPA believes that the application of emission control technologies on
marine engines and vessels for meeting the proposed evaporative emissions standards would not
lead to an increase in incremental risk of fires or burns, and in many cases may incrementally
5-107
-------
Draft Regulatory Impact Analysis
decrease safety risks in certain situations..
5-108
-------
Feasibility of Evaporative Emission Control
APPENDIX 5A: Diurnal Temperature Traces
Figure 5A-1: Temperature Trace for Personal Watercraft on Trailer
o>
0)
•o
2
0)
Q.
0)
7/10/01
12:00 AM
7/12/01
12:00 AM
7/14/01
12:00 AM
7/16/01
12:00 AM
7/18/01
12:00 AM
7/20/01
12:00 AM
7/22/01
12:00 AM
7/24/01
12:00 AM
Figure 5A-2: Temperature Trace for Jet Boat on Trailer
95.00
90.00
50.00
45.00
12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM
5-109
-------
Draft Regulatory Impact Analysis
Figure 5A-3: Temperature Trace for Runabout on Trailer
105.00
100.00
95.00
3
-------
Feasibility of Evaporative Emission Control
Figure 5A-5: Temperature Trace for Runabout in Water
Fuel Temp
Ambient Temp
Water Temp
12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM
12:00 AM
Figure 5A-6: Temperature Trace of Deckboat in Water
Fuel Temp
Ambient Temp
Water Temp
12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM
5-111
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Draft Regulatory Impact Analysis
APPENDIX 5B: Emission Results for Small SI Equipment Fuel Tanks
Showing Effect of Venting on Diffusion
5B.1 Diffusion Effects from Variable Temperature Diurnal Testing
Figure 5B-1: Diurnal/Diffusion Test Results for BM Metal Fuel Tank (2 Labs)
190
1 n. n.
8n
'in
S. 60
&
O
X
A n
9 0
0.0 -;
(
1 U III [JU I cl LUI U
—•—Stock Cap Vent, Lab 1
Qtnr'lr O a n X/ont I ah 9
— •- Hose Vent, Lab 1
—* Hose Vent Lab 2
^^ ^^
j
*^
^^
J»r" ,•'
^>
»*£_
^"
^ ^^
-^* ^^=^^*^'
^5^-*r~*r~*
) 3 6 9 12 15 18 21 2
Test Hours
60.0
• en n
4^
->• K3 CO -li. C
P O O O O C
O o O O O C
Temperature [deg C]
5-112
-------
Feasibility of Evaporative Emission Control
Figure 5B.1-2: Diurnal/Diffusion Test Results for BP Plastic Fuel Tank
8 0
7 0 -
6 0
5 0
In1
E
2 4 n
a 4'° '
o
I 30
2 0 -
1 0 -
0.0 i
C
^_j
X" ^^\ ^^^
s i^C.
-^ ^/r^ "-- — -—
/*" Temperature
x* — * ivioQiTieo uap veni
^ * -m- Stock Cap Vent
/* —^- Hose Vent
ff
) 3 6 9 12 15 18 21 2
Test Hours
40.0
j!
35.0
30.0
o"
25.0 g>
2,
20.0 oT
3
15.0 g
a)
10.0 1"
a)
5.0
0.0
4
Figure 5B.1-3: Diurnal/Diffusion Test Results for HP Plastic Fuel Tank
1 ?
1 n
n 8
E
5 n R
O) U'D
0
0 4
0 ?
n n •
Temperature
^^ """" — ^^ — •— Stock Cap Vent
jr — -+- Hose Vent
_/ ^^^^_
* w^*^
&-
^••-
0 3 6 9 12 15 18 21 2
Test Hours
48.0
40.0
«-»S
0)
H,
24.0 0
I 16.0 0
a.
0
8.0 1-
0.0
4
5-113
-------
Draft Regulatory Impact Analysis
Figure 5B.1-4: Diurnal/Diffusion Test Results for TP Plastic Fuel Tank
1 fi ^
1 A
1 9
1/T 1 0
2 08
s
° 06
0 4
n 9
n n i
c
/* ^\
/ ^x
/
-/
^,,-^*^
/ /^
//*
4 «'
, ^
) 3 6 9 12 1£
Test Hours
Temperature
^^ Stock Cap Vent
—* nose veni
^^^^^
—
^^^^A^^r^r^^
18 21 2
/in n
'l-U.U
•3c n
•an n
O
oc n O)
20. U gj
2,
on n
-------
Feasibility of Evaporative Emission Control
5B.2 Isothermal Results for Small SI Equipment Fuel Tanks Showing Effect of Venting on
Diffusion
Figure 5B.2-1: Isothermal Diffusion Test Results for BM Metal Fuel Tank
7 nn
6nn
't/j1
EA nn
ss
s
-3 nn _
o •i-uu "
I
o nn
1 00
n nn i
c
•
•r
/B
•^^SS^^^^^^™"^^^^™^"™"^""^^"^!S^S^SSi^^2^S2!!25S5!2^S5S!S!
~~s~
•^ Temp (cap)
_/ ^— Temp (hose)
^B I \ /
_/• -m- Stock Cap Vent
V '
X -^A— Hose Vent
X
i^~*-***~*~
-:-.— ******
fZJEZSL..
) 3 6 9 12 15 18 21 2
Test Hours
^^ n
oU.U
^O.U Q
0)
a)
20.0 ^.
£
15.0 ,£
JO
>_
0
•inn Q.
> 10.0 |-
0)
«?n "~
O.O
n n
4
Figure 5B.2-2: Isothermal Diffusion Test Results for BP Plastic Fuel Tank
7 nn
6 00 -
5 00
't/j'
EA nn
(0
S
o nn
o -3-00
I
2nn
•i nn
1 .UU
0.00 i
(
9
<*
/*
X
it
^
S
*
«*
j^
4^
Jf
«•
x'
/
0
/
#
"•—•-»- B=l=f==H='=¥==B=i=*==B=B=='
Temp (mod cap)
Temp (cap)
Temp (hose)
-•- Stock Cap Vent
^^ Stock Cap Vent
^*^ Hose Vent
•=_j__B-=fcJ==B=:B 1
_ — • —
) 3 6 9 12 15 18 21 2
Test Hours
35.0
•^n n
->•->• ro ro c
en o en o en c
° CD CD CD CD C
Temperature [deg C]
0.0
4
5-115
-------
Draft Regulatory Impact Analysis
Figure 5B.2-3: Isothermal Diffusion Test Results for HP Plastic Fuel Tank
n oj^
n ^n
n 9s
"to1
En on
ss
- 015
o U-I!D
X
n 1 n
Of)C
n nn •
-^-^"
i^*^ - -^^
^^
.?^^
Z^
^4-*
^—Temperature
^^ Stock Cap Vent
^A^ Hose Vent
0 3 6 9 12 15 18 21 2
Test Hours
35.0
30.0
, 25'° 0
O)
0)
on n w
*>.
p cn o en c
b b b b c
Temperature [c
Figure 5B.2-4: Isothermal Diffusion Test Results for TP Plastic Fuel Tank
n ^S -r
0 30
n pi; _
fcft
En ?n
ss
o °-15
I
01 n
0 05
Onn j
****
^^^
*^^
-^*
M^
Temp (cap)
^— Temp (hose)
-m- Stock Cap Vent
—^- Hose Vent
.uu • — — i — — i — — i — i — i — i
0 3 6 9 12 15 18 21 2
Test Hours
4S.
->•->• ro ro co co
penoeno enoen
o o bob bob
Temperature [deg C]
5-116
-------
Feasibility of Evaporative Emission Control
APPENDIX 5C: Diurnal Emission Results: Canister and Passive-Purge
Diurnal Emissions for a 30
50.00
45.00
40.00
«* 35.00
w 30.00
o
I 25.00
0)
'••= 20.00
o
J 15.00
lil
10.00
5.00
0.00
C
Gallon Marine
Fuel Tank with 2.1 L Canister, 72-96F
Baseline Emission Level
*
I |
) 5 10 15
n n
*
• Diurnal Emissions
QMonday Outliers
I
20 25
30
Test Days
5-117
-------
Draft Regulatory Impact Analysis
APPENDIX 5D: Material Properties of Common Fuel System Materials
This appendix presents data on permeation rates for a wide range of materials that can be
used in fuel tanks and hoses. The data also includes effects of temperature and fuel type on
permeation. Because the data was collected from several sources, there is not complete data on
each of the materials tested in terms of temperature and test fuel. Table D-l gives an overview
of the fuel systems materials included in the data set. Tables D-2 through D-3 present
permeation rates using Fuel C, a 10 percent ethanol blend (CE10), and a 15 percent methanol
blend (CE15) for the test temperatures of 23, 40, 50, and 60°C.
Table 5D-1: Fuel System Materials
Material Name
ACN NBR
Carilon
Celcon
CFM
CO
CR
CSM
E14659
E14944
ECO
ETER
ETFE
EVOH
FEE
FEP
FKM
FPA
FVMQ
GFLT
HOPE
HOPE
HNBR
LDPE
NBR
Nylon 12
PBT
PFA
Polyacetal
PTFE
PVDF
THV
Composition
acrylonitrile
aliphatic poly-ketone thermoplastic
acetal copolymer
fluoroelastomer
epichlorohydrin homopolymer
polychloroprene polymer
chlorosulfonated polyethylene
fluoropolymer film
fluoropolymer film
epichlorohydrin-ethylene oxide copolymer
epichlorohydrin-ethylene oxide terpolymer
ethylenetetrafluoroethylene, fluoroplastic
ethylene vinyl alcohol, thermoplastic
fluorothermoplastic
fluorothermoplastic
fluorocarbon elastomer
copolymer of tetrafluoroethylene and perfluoroalkoxy monomer
fluorovinyl methal silicone rubber (flourosilicone)
fluoroelastomer
high-density polyethylene
high density polyethylene
hydrogenated acrylonitrile-butadiene rubber
low density polyethylene
acrylonitrile-butadiene rubber
thermoplastic
polybutylene terephthalate, thermoplastic
fluorothermoplastic
thermoplastic
polytetrafluoroethylene, fluoroplastic
polyvinylidene fluoride, fluorothermoplastic
tetrafluoroethylene, hexafluoropropylene, vinyledene fluoride
5-118
-------
Feasibility of Evaporative Emission Control
Table 5D-2: Fuel System Material Permeation Rates at 23°C by Fuel Type
^ ^,217,218,219,220
Material Name
HOPE
Nylon 12, rigid
EVOH
Polyacetal
PBT
PVDF
NBR (33% ACN)
HNBR (44%ACN)
FVMQ
FKM Viton A200 (66%F)
FKM Viton B70 (66%F)
FKM Viton GLT (65 %F)
FKM Viton B200 (68%F)
FKM Viton GF (70%F)
FKM Viton GFLT (67%F)
FKM -2 120
FKM - 5830
Teflon FEP 1000L
Teflon PTFE
Teflon PFA 1000LP
Tefzel ETFE 1000LZ
Nylon 12 (GM grade)
Nitrile
Silicone Rubber
Fluorosilicone
FKM
FE 5620Q (65.9% fluorine)
FE 5840Q (70.2% fluorine)
PTFE
ETFE
PFA
THV500
FuelC
g-mm/m2/day
35
0.2
-
-
-
-
669
230
455
0.80
0.80
2.60
0.70
0.70
1.80
8
1.1
0.03
-
0.18
0.03
6.0
130
-
-
-
-
-
0.05
0.02
0.01
0.03
Fuel CE10
g-mm/m2/day
-
-
-
-
—
1028
553
584
7.5
6.7
14
4.1
1.1
6.5
-
—
0.03
-
0.03
0.05
24
635
—
-
16
7
4
-
-
-
-
CM15
g-mm/m2/day
35
64
10
3.1
0.4
0.2
1188
828
635
36
32
60
12
3.0
14
44
8
0.03
0.05
0.13
0.20
83
1150
6500
635
—
-
-
0.08*
0.04*
0.05*
0.3
* tested on CM20.
5-119
-------
Draft Regulatory Impact Analysis
Table 5D-3: Fuel System Material Permeation Rates at 40°C by Fuel Type
221,222
Material Name
Carilon
EVOH-F101
EVOH-XEP380
HOPE
LDPE
Nylon 12 (L2 10 IF)
Nylon 12 (L2140)
Celcon
Fortran PPS SKX-382
Celcon Acetal M90
Celanex PBT 3300 (30% GR)
Nylon 6
Dyneon El 465 9
Dyneon El 4944
ETFE Aflon COP
m-ETFE
ETFE Aflon LM730 AP
FKM-70 16286
GFLT 19797
Nitrile
FKM
FE 5620Q (65.9% fluorine)
FE 5840Q (70.2% fluorine)
THV-310X
THV-500
THV-610X
FuelC
g-mm/m2/day
0.06
<0.0001
<0.0001
90
420
2.0
1.8
0.38
-
-
-
-
0.25
0.14
0.24
0.27
0.41
11
13
-
—
-
-
-
0.31
-
Fuel CE10
g-mm/m2/day
1.5
0.013
-
69
350
28
44
2.7
0.12
0.35
3
26
-
-
0.67
-
0.79
35
38
1540
86
40
12
-
-
-
CM15
g-mm/m2/day
13
3.5
5.3
71
330
250
-
-
—
-
-
—
2.1
1.7
1.8
1.6
2.6
—
—
3500
120
180
45
5.0
3.0
2.1
Table 5D-4: Fuel System Material Permeation Rates at 50°C by Fuel Type
223
Material Name
Carilon
HOPE
Nylon 12(L2140)
Celcon
ETFE Afcon COP
FKM-70 16286
GFLT 19797
FuelC
g-mm/m2/day
0.2
190
4.9
0.76
-
25
28
Fuel CE10
g-mm/m2/day
3.6
150
83
5.8
1.7
79
77
CM15
g-mm/m2/day
_
-
-
-
-
-
-
5-120
-------
Feasibility of Evaporative Emission Control
Table 5D-5: Fuel System Material Permeation Rates at 60°C by Fuel Type
224,225,226,227
Material Name
Carilon
HOPE
Nylon 12 (L2140)
Celcon
ETFE Afcon COP
FKM-70 16286
GFLT 19797
polyeurethane (bladder)
THV-200
THV-310X
THV-510ESD
THV-500
THV-500 G
THV-610X
ETFE 6235 G
THV-800
FEP
FuelC
g-mm/m2/day
0.55
310
9.5
1.7
-
56
60
285
-
6.1
-
4.1
2.4
1.1
1.0
0.2
Fuel CE10
g-mm/m2/day
7.5
230
140
11
3.8
170
130
460
54
-
18
11
10
5.4
3.0
2.9
0.4
CM15
g-mm/m2/day
-
—
-
-
—
—
38
35
20
22
9.0
6.5
6.0
1.1
5-121
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Draft Regulatory Impact Analysis
APPENDIX 5E: Diurnal Test Temperature Traces
Table 5E-1: Temperature vs. Time Sequence for Proposed Diurnal Testing
Test
Time*
[minutes]
0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
900
960
1020
1080
1140
1200
1260
1320
1380
1440
Portable Fuel Tanks
SHED Air Temperature
Fahrenheit
72.0
72.5
75.5
80.3
85.2
89.4
93.1
95.1
95.8
96.0
95.5
94.1
91.7
88.6
85.5
82.8
80.9
79.0
77.2
75.8
74.7
73.9
73.3
72.6
72.0
Celsius
22.2
22.5
24.2
26.8
29.6
31.9
33.9
35.1
35.4
35.6
35.3
34.5
33.2
31.4
29.7
28.2
27.2
26.1
25.1
24.3
23.7
23.3
22.9
22.6
22.2
Installed Fuel Tanks
Boat < 26 feet (7.9m)
Fuel Temperature
Fahrenheit
78.0
78.3
79.8
82.2
84.6
86.7
88.6
89.6
89.9
90.0
89.8
89.1
87.9
86.3
84.8
83.4
82.5
81.5
80.6
79.9
79.4
79.0
78.7
78.3
78.0
Celsius
25.6
25.7
26.5
27.9
29.2
30.4
31.4
32.0
32.2
32.2
32.1
31.7
31.0
30.2
29.3
28.6
28.0
27.5
27.0
26.6
26.3
26.1
25.9
25.7
25.6
Installed Fuel Tanks
Boat >26 feet (7.9m)
Fuel Temperature
Fahrenheit
81.6
81.7
82.3
83.3
84.2
85.1
85.8
86.2
86.4
86.4
86.3
86.0
85.5
84.9
84.3
83.8
83.4
83.0
82.6
82.4
82.1
82.0
81.9
81.7
81.6
Celsius
27.6
27.6
27.9
28.5
29.0
29.5
29.9
30.1
30.2
30.2
30.2
30.0
29.7
29.4
29.1
28.8
28.5
28.3
28.1
28.0
27.9
27.8
27.7
27.6
27.6
* Repeat as necessary
5-122
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Feasibility of Evaporative Emission Control
Chapter 5 References
1. Reddy, S., "Prediction of Fuel Vapor Generation From a Vehicle Fuel Tank as a Function of Fuel RVP and
Temperature," SAE Paper 892089, 1989, Docket Identification EPA-HQ-OAR-2004-0008-0169.
2. Gushing, T., "Fuel Tank Hydrocarbon Emission Testing," prepared by Sterling Performance for the U.S. EPA,
Report #040107, September 30, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0137.
3. Gushing, T., "Fuel Tank Hydrocarbon Emission Testing," prepared by Sterling Performance for the U.S. EPA,
Report #040137, November 3, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0138.
4. "Evaporative Emissions from Offroad Equipment," California Air Resources Board, June 22, 2001, Docket
Identification EPA-HQ-OAR-2004-0008-0051.
5. "Docket No. A-2000-02; Notice or Proposed Rulemaking for the Control of Emissions from Spark-Ignition
Marine Vessels and Highway Motorcycles; 40 C.F.R. Parts 86, 90, 1045, 1051, and 1068," Comments from the
National Marine Manufacturers Association, Docket Identification EPA-HQ-OAR-2004-0008-0211.
6. "Before the United States Environmental Protection Agency, Comments by Brunswick Corporation, Notice of
Proposed Rulemaking, Part 1045 Control of Emissions from Spark-Ignition Marine Vessels," Comments from
Brunswick Corporation, Docket Identification EPA-HQ-OAR-2004-0008-0192.
7. "Diurnal Emissions Testing of Walk-Behind Mowers Configured with Fuel Tank Pressure Relief Valves
(September 2002)," California Air Resources Board, September 17, 2002, Docket Identification EPA-HQ-OAR-
2004-0008-0052.
8. "Aboveground Storage Tanks (AST); Enhanced Vapor Recovery Regulation," California Air Resources Board,
August 16, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0413.
9. Email from Pamela Gupta, California Air Resources Board, to Mike Samulski, U.S. EPA, "Aboveground Storage
Tanks (ASTs) Field Study Presentation," September 6, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0420.
10. Samulski, M., "Characterization and Control of Evaporative Emissions from Fuel Tanks in Nonroad
Equipment," SAE Paper 2006-32-0094, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0424.
11. Beverley, K., Clint, I, Fletcher, P., "Evaporation Rates of Pure Liquids Measured Using a Gravimetric
Technique," Phys. Chem. Chem. Phys., 1999, 1, 149-153, Received July 9, 1998, Accepted October 13, 1998,
Docket Identification EPA-HQ-OAR-2004-0008-0103.
12. Batterman, S., Yu, Y., Jia, C., Godwin, C., "Non-methane Hydrocarbon Emissions from Vehicle Fuel Caps,"
Atmospheric Environment 39 (2005), Received May 27, 2004, Accepted December 1, 2004, Docket Identification
EPA-HQ-OAR-2004-0008-0102.
13. Sterling Performance, "USEPA Fuel Tank Hydrocarbon Emission Testing," prepared for the U.S. EPA, Report
Number 040195, January 26, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0139.
14. "24 hr EPA Diurnal Micro SHED of Lawn Mower Gas Tanks," Testing Services Group, Reports L50483 5-1.1,
Prepared for U.S. EPA, April 20, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0140.
15. "24 hr EPA Diurnal Micro SHED of Lawn Mower Gas Tanks," Testing Services Group, Reports L50483 5-1.2,
Prepared for U.S. EPA, April 20, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0141.
5-123
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Draft Regulatory Impact Analysis
16. "24 hr EPA Diurnal MicroSHED of Lawn Mower Gas Tanks," Testing Services Group, Reports L504835-1.3,
Prepared for U.S. EPA, April 20, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0142.
17. "24 hr EPA Isothermal MicroSHED of Lawn Mower Gas Tanks," Testing Services Group, Reports L504835-
2.1, Prepared for U.S. EPA, April 20, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0143.
18. "24 hr EPA Isothermal MicroSHED of Lawn Mower Gas Tanks," Testing Services Group, Reports L504835-
2.2, Prepared for U.S. EPA, April 20, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0144.
19. "24 hr EPA Isothermal MicroSHED of Lawn Mower Gas Tanks," Testing Services Group, Reports L504835-
2.3, Prepared for U.S. EPA, April 20, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0145.
20. Haskew, H., Cadman, W., "Evaporative Emissions Under Real Time Conditions," SAE Paper 891121, 1989,
Docket Identification EPA-HQ-OAR-2004-0008-0168.
21. Haskew, H., Cadman, W., Liberty, T., "The Development of a Real-Time Evaporative Emissions Test," SAE
Paper 901110, 1990, Docket Identification EPA-HQ-OAR-2004-0008-0170.
22. Tschantz, M., "Activated Carbon for Use in Marine Evaporative Control Applications," Presented by
MeadWestvaco Corporation at the 2004 International Boatbuilders Exposition, October 25, 2004, Docket
IdentificationEPA-HQ-OAR-2004-0008-0040.
23. Internal MeadWestvaco memorandum from M. Tschantz to C. Pierson, "Preliminary 3 mm SeaGuard™
Specifications," August 31, 2005, Docket IdentificationEPA-HQ-OAR-2004-0008-0136.
24. "A Picture Book Concerning the NMMA 2005 Summer Test Program: Carbon Canisters for Marine Diurnal
Control," Harold Haskew & Associates, Inc., July 12, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0127.
25. Dr. Michael Tschantz, "Summer Test Program Carbon Analysis," presented by Meadwestvaco Corporation at
the 2005 International Boatbuilders Exhibition and Conference, October 20, 2005, Docket Identification EPA-HQ-
OAR-2004-0008-0290.
26. Andreatta, D., Heydinger, G., Bixel, R., Park, I, Jorgensen, S., "Evaluation of the Ignition Hazard Posed by
Onboard Refueling Vapor Recovery Canisters," SAE Paper 2001-01-0731, 2001, Docket Identification EPA-HQ-
OAR-2004-0008-0494.
27. "Diurnal Testing of Off-Road Equipment Retrofitted with Carbon Canister Evaporative Emission Control
Systems (March 2003)," California Air Resources Board, March 25, 2003, Docket Identification EPA-HQ-OAR-
2004-0008-0053.
28. Haskew, H., Cadman, W., Liberty, T., "The Development of a Real-Time Evaporative Emissions Test," SAE
Paper 901110, 1990, Docket Identification EPA-HQ-OAR-2004-0008-0170.
29. Email from Reid Clontz, MeadWestvaco, to Mike Samulski, U.S. EPA, "Temperature and Ethanol Questions,"
July 7, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0423.
30. American Boat and Yacht Council, "H-24 Gasoline Fuel Systems," 2005, Docket Identification EPA-HQ-OAR-
2004-0008-0429.
31. "Diurnal Emissions Testing of Walk-Behind Mowers Configured with Fuel Tank Pressure Relief Valves
(September 2002)," California Air Resources Board, September 17, 2002, Docket Identification EPA-HQ-OAR-
2004-0008-0052.
5-124
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Feasibility of Evaporative Emission Control
32. Letter from Bill Scott, Country Industries Technologies, to Mike Samulski U.S. EPA, regarding a gas tank vent
design, July 20, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0287.
33. Compact Membrane Systems, Inc., www.compactmembrane.com, Docket Identification EPA-HQ-O AR-2004-
0008-0100.
34. Koch, W., "Developing Technology for Enhanced Vapor Recovery: Part 1 - Vent Processors," Petroleum
Equipment & Technology, February/March 2001, Docket Identification EPA-HQ-OAR-2004-0008-0099.
35. Membrane Technology & Research, Inc., www.mtrinc.com, Docket Identification EPA-HQ-OAR-2004-0008-
0101.
36. "New Evaporative Control System for Gasoline Tanks," Memorandum from Chuck Moulis, EPA to Glenn
Passavant, Nonroad Center Director, EPA, March 1, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0261.
37. Letter from Kevin Madison, Top Dog Systems, to Mike Samulski, U.S. EPA, regarding the Top Dog vaporless
fuel system, April 23, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0258.
38. Facsimile from Bob Hazekamp, Top Dog Systems to Mike Samulski, U.S. EPA, "Permeation of Polyurethane
versus THV Materials @ 60°C," January 14, 2002, Docket A-2000-01, Docket Identification EPA-HQ-O AR-2004-
0008-0435.
39. Emails from Steve Vaitses, Seacurefill to Mike Samulski, U.S. EPA, "VCS diagrams 1-4 attachments," and
"VCS attachments 5-7," April 27, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0395.
40. Testing Services Group, "Marine Fuel Tank Vapor Trap Diurnal Emissions Testing; 48 hr EPA (custom)
Diurnal," TSG Report No. L605816-1.2, July 14, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0445.
41. Fox, J., "Fuel Temperature Measurements on Small Equipment," Fox Automotive, August 2004, Docket
Identification EPA-HQ-OAR-2004-0008-0181.
42. Gushing, T., "Fuel Tank Hydrocarbon Emission Testing," prepared by Sterling Performance for the U.S. EPA,
Report #040107, September 30, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0137.
43. Gushing, T., "Fuel Tank Hydrocarbon Emission Testing," prepared by Sterling Performance for the U.S. EPA,
Report #040137, November 3, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0138.
44. Wong, W., "Addition of Evaporative Emissions for Small Off-Road Engines," California Air Resources Board
OFFROAD Model Change Technical Memo, Revised April 21, 2003, Docket OAR-2004-0008, Document OAR-
2004-0008-0006.
45. Tuckner, P., Baker, J., "Fuel Permeation Testing using Gravimetric Methods," SAE Paper 2000-01-1096, 2000,
Docket Identification EPA-HQ-O AR-2004-0008-0160.
46. Allen, S.J., "Fuel Tank Permeability Test Procedure Development; Final Report," U.S. Coast Guard, December
1986, Docket Identification EPA-HQ-OAR-2004-0008-0231.
47. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.
48. "Permeation Rates of Small Off Road Engine High-Density Polyethylene Fuel Tanks (April 2001 Testing), June
8, 2001, California Air Resources Board, Docket Identification EPA-HQ-OAR-2004-0008-0146.
5-125
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Draft Regulatory Impact Analysis
49. "Permeation Rates of Small Off Road Engine High-Density Polyethylene Fuel Tanks (February 2001 Testing),
June 8, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0147.
50. "Permeation Rates of High-Density Polyethylene Fuel Tanks (June 2001), June 12, 2001, California Air
Resources Board, Docket Identification EPA-HQ-OAR-2004-0008-0148
51. "Permeation Rates of High-Density Polyethylene Fuel Tanks (May 2001), June 11, 2001, California Air
Resources Board, Docket Identification EPA-HQ-OAR-2004-0008-0149.
52. "Average Permeation Rates of High-Density Polyethylene Off-Road Equipment Fuel Tanks Using a Surface
Area Approach, (March 2002)," March 15, 2002, California Air Resources Board, Docket Identification EPA-HQ-
OAR-2004-0008-0256.
53. "Test Method 513; Determination of Permeation for Spill-Proof Systems," California Air Resources Board,
Adopted July 6, 2000, Docket Identification EPA-HQ-OAR-2004-0008-0150.
54. www.arb.ca.gov/msprog/spillcon/reg.htm, Updated March 26, 2001, Copy of linked data reports available in
Docket, Docket Identification EPA-HQ-OAR-2004-0008-0186.
55. Email from Jim Watson, California Air Resources Board, to Phil Carlson, U.S. EPA, "Early Container Data,"
August 29, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0200.
56. "Test Method 513; Determination of Permeation for Spill-Proof Systems," California Air Resources Board,
Adopted July 6, 2000, Docket Identification EPA-HQ-OAR-2004-0008-0150.
57. Lockhart, M., Nulman, M., Rossi, G., "Estimating Real Time Diurnal Permeation from Constant Temperature
Measurements," SAE Paper 2001-01-0730, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0161.
58. Hopf, G., Ries, H., Gray, E., "Development of Multilayer Thermoplastic Fuel Lines with Improved Barrier
Properties," SAE Paper 940165, 1994, Docket Identification EPA-HQ-OAR-2004-0008-0174.
59. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.
60. Haskew, H., McClement, D., "Fuel Permeation from Automotive Systems; Final Report," prepared for the
California Air Resources Board and the Coordinating Research Council, CRC Project No. E-65, September 2004,
Docket Identification EPA-HQ-OAR-2004-0008-0151.
61. Tuckner, P., Baker, J., "Fuel Permeation Testing using Gravimetric Methods," SAE Paper 2000-01-1096, 2000,
Docket Identification EPA-HQ-OAR-2004-0008-0160.
62. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.
63. Stevens, M., Demorest, R., "Fuel Permeation Analysis Method Correction," SAE Paper 1999-01-0376, 1999,
Docket Identification EPA-HQ-OAR-2004-0008-0157.
64. Lockhart, M., Nulman, M., Rossi, G., "Estimating Real Time Diurnal Permeation from Constant Temperature
Measurements," SAE Paper 2001-01-0730, Docket Identification EPA-HQ-OAR-2004-0008-0161.
65. Testimony of and Presentation, H. Haskew, President, Harold Haskew & Associates, MI, October 7, 2002,
Docket Identification EPA-HQ-OAR-2004-0008-0202.
5-126
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Feasibility of Evaporative Emission Control
66. Haskew, H., McClement, D., "Fuel Permeation from Automotive Systems; Final Report," prepared for the
California Air Resources Board and the Coordinating Research Council, CRC Project No. E-65, September 2004,
Docket Identification EPA-HQ-OAR-2004-0008-0151.
67. Email from Jim Watson, California Air Resources Board, to Mike Samulski, U.S. EPA, "Vapor Loss for
Variable Volume Containers.xls," October 26, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0291.
68. Email from Harold Haskew, Harold Haskew & Associates, to Mike Samulski, U.S. EPA, "High-low permeation
data," April 9, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0238.
69. Kathios, D., Ziff, R., Petrulis, A., Bonczyk, J., "Permeation of Gasoline and Gasoline-alcohol Fuel Blends
Through High-Density Polyethylene Fuel Tanks with Different Barrier Technologies," SAE Paper 920164, 1992,
Docket Identification EPA-HQ-OAR-2004-0008-0172.
70. www.arb.ca.gov/msprog/spillcon/reg.htm, Updated March 26, 2001, Copy of linked data reports available in the
Docket, Docket Identification EPA-HQ-OAR-2004-0008-0186.
71. Email from Jim Watson, California Air Resources Board, to Phil Carlson, U.S. EPA, "Early Container Data,"
August 29, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0200.
72. "Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine Fuel Tanks,"
California Air Resources Board, June 21, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0152.
73. "Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine Fuel Tanks,"
California Air Resources Board, March 7, 2003, Docket Identification EPA-HQ-OAR-2004-0008-0153.
74. Conversation between Mike Samulski, U.S. EPA and Tom Schmoyer, Sulfo Technologies, June 17, 2002.
75. "Sulfo Data", E-mail from Tom Schmoyer, Sulfotechnologies to Mike Samulski, U.S. EPA, March 17, 2003,
Docket Identification EPA-HQ-OAR-2004-0008-0223.
76. "ADDENDUM TO: Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine
Fuel Tanks," California Air Resources Board, March 27, 2003, Docket Identification EPA-HQ-OAR-2004-0008-
0154.
77. "Resin and Additives - SOS Compatible," Email from Tom Schmoyer, Sulfo Technologies to Mike Samulski
and Glenn Passavant, U.S. EPA, June 19, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0215.
78. Email from Jim Watson, California Air Resources Board, to Mike Samulski, U.S. EPA, "Attachment to Resin
List," August 30, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0234.
79. Walles, B., Nulford, L., "Five Year Durability Tests of Plastic Gas Tanks and Bottles with Sulfonation Barrier,"
Coalition Technologies, LTD, for Society of Plastics Industry, January 15, 1992, Docket Identification EPA-HQ-
OAR-2004-0008-0233.
80. Kathios, D., Ziff, R., "Permeation of Gasoline and Gasoline-Alcohol Fuel Blends Through High-Density
Polyethylene Fuel Tanks with Different Barrier Technologies," SAE Paper 920164, 1992, Docket Identification
EPA-HQ-OAR-2004-0008-0172.
81. www.arb.ca.gov/msprog/spillcon/reg.htm, Updated March 26, 2001, Copy of linked data reports available in
Docket, Docket Identification EPA-HQ-OAR-2004-0008-0186.
82. "Permeation Rates of Blitz Fluorinated High Density Polyethylene Portable Fuel Containers," California Air
Resources Board, April 5, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0155.
5-127
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Draft Regulatory Impact Analysis
83. Email from Jim Watson, California Air Resources Board, to Phil Carlson, U.S. EPA, "Early Container Data,"
August 29, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0200.
84. www.pensteel.co.uk/light/smp/fluorination.htm. A copy of this site, as downloaded on August 13, 2004, is
available in Docket, Docket Identification EPA-HQ-OAR-2004-0008-0214.
85. "Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine Fuel Tanks,"
California Air Resources Board, June 21, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0152.
86. "Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine Fuel Tanks,"
California Air Resources Board, March 7, 2003, Docket Identification EPA-HQ-OAR-2004-0008-0153.
87. Kathios, D., Ziff, R., "Permeation of Gasoline and Gasoline-Alcohol Fuel Blends Through High-Density
Polyethylene Fuel Tanks with Different Barrier Technologies," SAE Paper 920164, 1992, Docket Identification
EPA-HQ-OAR-2004-0008-0172.
88. "SORE Component EO Summary," email from Jim Watson, California Air Resources Board, to Mike Samulski,
U.S. EPA, August 18, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0405.
89. "Fluorination Information," e-mail from Doug McGregor, BMW, to Mike Samulski, US EPA, August 8, 2003,
Docket Identification EPA-HQ-OAR-2004-0008-0259.
90. "Final Report: Permeation Testing of Injection Molded Walk Behind Mower (WBM) Fuel Tanks using
California's TP-901 Procedures," Automotive Testing Laboratories, Inc., August 30, 2005, Docket Identification
EPA-HQ-OAR-2004-0008-0182.
91. "Baseline Test Results: Permeation Testing of Injection Molded Walk Behind Mower (WBM) Fuel Tanks using
Federal Test Procedures," Automotive Testing Laboratories, Inc., August 30, 2005, Docket Identification EPA-HQ-
OAR-2004-0008-0183.
92. "Final Results: Permeation Testing of Injection Molded Walk Behind Mower (WBM) Fuel Tanks using Federal
Test Procedures," Automotive Testing Laboratories, Inc., July 28, 2006, Docket Identification EPA-HQ-OAR-2004-
0008-0419.
93. "Selar RB Technical Information," Faxed from David Zang, Dupont, to Mike Samulski, U.S. EPA on May 14,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0221.
94. Lyn, K., "A Study on Problems with Aluminum Fuel Tanks in Recreational Boats," Underwriters Laboratories
Inc., sponsored by USCG, 1994, Docket Identification EPA-HQ-OAR-2004-0008-0098.
95. E-mail from Alan Dubin, Ticona, to Mike Samulski, U.S. EPA, "Fuel Permeation Chart and Aggressive Fuels
Brochure," July 31, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0196.
96. Samulski, M., "Permeation Emission Testing on Three Roto-Molded Acetal Copolymer Fuel Tanks," Memo to
Docket OAR-2004-0008, October 25, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0443.
97. E-mail from Jim Watson, California ARB to Mike Samulski, U.S. EPA, "fuel tank specs.xls," March 6, 2006,
Docket Identification EPA-HQ-OAR-2004-0008-0357.
98. Chambers, J., "Marine Fuel Containment... A Permanent Solution," Presentation by Engineered Composite
Structures Inc. at the 2004 International Boatbuilders Exposition, October 25, 2004, Docket Identification EPA-HQ-
OAR-2004-0008-0037.
5-128
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Feasibility of Evaporative Emission Control
99. "Fluorination Information," e-mail from Doug McGregor, BMW, to Mike Samulski, US EPA, August 8, 2003,
Docket Identification EPA-HQ-OAR-2004-0008-0259.
100. Fead, E., Vengadam, R., Rossi, G., Olejnik, A., Thorn, J., "Speciation of Evaporative Emissions from Plastic
Fuel Tanks," SAE Paper 981376, 1998, Docket Identification EPA-HQ-OAR-2004-0008-0175.
101. Email from Dennis Goodenow, California Air Resources Board, to Mike Samulski, U.S. EPA, "Coextruded
PFC Data, September 11, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0436.
102. Solvay Advanced Polymers, "Solvay Advanced Polymers Unveils Modified Ixef® Polyarylamide Barrier
Material for Automotive Fuel Systems," Press Release, March 2, 200, Docket Identification EPA-HQ-OAR-2004-
0008-0539.
103. O'Brien, Partridge, Clay, "New Materials and Multi-Layer Rotomolding Technology for Higher Barrier
Performance Rotomolded Tanks," Atofina Chemicals, Inc., Presented at the Topcon Rotational Molding by Design
Conference, June 6-8, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0044.
104. Samulski, M., "Permeation Emission Testing of Two Multi-Layer Roto-Molded Fuel Tanks," Memo to Docket
OAR-2004-0008, August 31, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0132.
105. Partridge, R., "Petro-SealTM for Ultra-Low Permeation," Arkema Inc., Presentation at 2004 International
Boatbuilders Exposition, October 25, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0038.
106. "Test Report 16514-1A: NMMA/USCG Tests of Prototype Fuel Tank for Atofina Chemicals, Inc.," IMANNA
Laboratory, July 16, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0416.
107. "Test Report 16544-1A: NMMA/USCG Tests of Prototype Fuel Tank for Atofina Chemicals, Inc.," IMANNA
Laboratory, July 16, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0417.
108. "Test Report 17474-1: NMMA/USCG Tests of 40 Gallon Prototype Fuel Tank for Arkema, Inc.," IMANNA
Laboratory, October 12, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0418.
109. "Final Report, Fuel Tank Testing, Procedure Number: SAE J288 DEC 02, Sections 4.2, 4.3," MGA Research
Corporation, October 19, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0406.
110. "SORE Component EO Summary," email from Jim Watson, California Air Resources Board, to Mike
Samulski, U.S. EPA, August 18, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0405.
111. Faler, Gary, "Cyclics CBT® Resin for Dual Layer Applications in Rotomolding," Cyclics Corporation, August
2006, Docket Identification EPA-HQ-OAR-2004-0008-0415.
112. Faler, Gary, ""Cyclics CBT® Resin for Rotomolding," Cyclics Corporation, Presented at ARMO 2006
Convention & Exposition, September, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0414.
113.Graham, B., Cook, D., "Measurement of Fuel Barrier Properties of Rotational Molded Materials," Article from
ANTEC 2006 Rotational Molding Division, May 12, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0404.
114. Fish, D., "Advanced Polymer Concepts," Presentation at the 2004 International Boatbuilders Exposition,
October 25, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0039.
115. Bauman, B., "Advances in Plastic Fuel Tanks," Presentation by Fluoro-Seal International at the 2004
International Boatbuilders Exposition, October 25, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0036.
5-129
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Draft Regulatory Impact Analysis
116. Bauman, B., "Advances in Plastic Fuel Tanks," Presentation by Fluoro-Seal International at the 2004
International Boatbuilders Exposition, October 25, 2004, Docket Identification EPA-HQ-OAR-2000-0008,
Document OAR-2004-0008-0036.
117. SAE Surface Vehicle Standard, "Marine Fuel Hoses," Society of Automotive Engineers J 1527, Issued 1985-
12, Revised 1993-02, Docket Identification EPA-HQ-OAR-2004-0008-0177.
118. American Society for Testing and Materials, "Standard Test Method for Rubber Property-Effects of Liquids,"
ASTM D 471-06, November 2006, Docket Identification EPA-HQ-OAR-2004-0008-0511.
119. "Public Hearing on Proposed Evaporative Emission Standards for New Marine Vessels that Use Spark-Ignition
Engines," Held on Monday, October 7, 2002 at the U.S. Environmental Protection Agency, Office of Transportation
and Air Quality, in Ann Arbor, Michigan, De Scribe Reporting, Inc., Docket Identification EPA-HQ-OAR-2004-
0008-0265.
120. "Test Report: 24 hr MicroShed Test on 3 Standard Fuel Hoses," Testing Services Group, TSG Report Number
L201672-2.5, July 29, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0227.
121. Akron Rubber Development Laboratory, "Test Report PN# 50107" Prepared for the U.S. EPA, December 13,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0184.
122. Akron Rubber Development Laboratory, "Test Report PN# 50108" Prepared for the U.S. EPA, December 13,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0185.
123. "Test Report: Marine Fuel Hose Testing; 6-hour/28°C Constant Temperature MicroSHED after a cumulative
13-week soakinIE-10 Test Fuel at40°C," Testing Services Group, TSG Report Number L404396-1.1A, January 20,
2005, Docket Identification EPA-HQ-OAR-2004-0008-0407.
124. "Test Report: Permeation by Weight Loss," Testing Services Group, TSG Report Number L505371-6.1, May
15, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0409.
125. Harold Haskew, "NMMA/EPA Meeting," Harold Haskew & Associates, Inc, presented at NMMA/EPA
meeting on January 24, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0359.
126. SAE Vehicle Recommended Practice, "Personal Watercraft Fuel Systems," Society of Automotive Engineers J
2046, Issued January 19, 1993, Docket Identification EPA-HQ-OAR-2004-0008-0179.
127. Memorandum from Mike Samulski to Docket A-2000-02, "Hose Permeation Data from Saint-Gobain
Performance Plastics," October 17, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0210.
128. SAE Recommended Practice J30, "Fuel and Oil Hoses,"June 1998, Docket Identification EPA-HQ-OAR-
2004-0008-0176.
129. Baltz, G., "Effects of Alcohol Extended Fuels on the Rate of Fuel Hose Permeation," SAE Paper 880709,
Presented at the International Congress and Exposition February 29-March 4, 1988, Docket Identification EPA-HQ-
OAR-2004-0008-0167.
130. "OPEI Fuel Line Permeation Results," Walbro Engine Management, April 12, 2006, Docket Identification
EPA-HQ-OAR-2004-0008-0440.
131. Horvath, J., "Optimizing Permeation Resistance and Low Temperature Flexibility in Heat Resistant NBR Fuel
Hose," SAE Paper 790661, presented at the Passenger Car Meeting, June 11-15, 1979, Docket Identification EPA-
HQ-OAR-2004-0008-0166.
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Feasibility of Evaporative Emission Control
132. MacLachlan, I, "Automotive Fuel Permeation Resistance - A Comparison of Elastomeric Materials," SAE
Paper 790657, presented at the Passenger Car Meeting, June 11-15, 1979, Docket Identification EPA-HQ-OAR-
2004-0008-0165.
133. Testing Services Group, "Marine Fuel Hose MicroSHED Testing; 6-hour/28°C Constant Temperature
MicroSHED after a cumulative 13-week soak in IE-10 Test Fuel at 40°," TSG Report No. L404396-1.1A, January
24, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0407.
134. Testing Services Group, "Marine Fuel Hose MicroSHED Testing; 24-hourEPA MicroSHED after a cumulative
2-week soak in IE-10 Test Fuel at 40°," TSG Report No. L404396-2.1A, January 24, 2005, Docket Identification
EPA-HQ-OAR-2004-0008-0408.
135. Harold Haskew, "Marine Fuel System Hose Permeation Testing: 2nd Progress Report," Harold Haskew &
Associates, Inc., testing performed at Sterling Performance Testing Laboratory, October 3, 2005, Docket
IdentificationEPA-HQ-OAR-2004-0008-0358.
136. Harold Haskew, "Marine Fuel System Hose Permeation Testing: 2nd Progress Report," Harold Haskew &
Associates, Inc., testing performed at Sterling Performance Testing Laboratory, October 3, 2005, Docket
IdentificationEPA-HQ-OAR-2004-0008-0358.
137. Harold Haskew, "NMMA/EPA Meeting," Harold Haskew & Associates, Inc, presented at NMMA/EPA
meeting on January 24, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0359.
138. "Test Report: Permeation by Weight Loss," Testing Services Group, TSG Report Number L505371-6.1, May
15, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0409.
139. Sterling Performance, "U.S.E.P.A. Fuel Line Permeation 050085; Version 1.0," August 13, 2005, Docket
IdentificationEPA-HQ-OAR-2004-0008-0428.
140. Denbow, R., Browning, L., Coleman, D., "Report Submitted for WA 2-9, Evaluation of the Costs and
Capabilities of Vehicle Evaporative Emission Control Technologies," ICF, ARCADIS Geraghty & Miller, March
22, 1999, Docket Identification EPA-HQ-OAR-2004-0008-0194.
141. Denbow, R., Browning, L., Coleman, D., "Report Submitted for WA 2-9, Evaluation of the Costs and
Capabilities of Vehicle Evaporative Emission Control Technologies," ICF, ARCADIS Geraghty & Miller, March
22, 1999, Docket Identification EPA-HQ-OAR-2004-0008-0194.
142. SAE Recommended Practice J2260, "Nonmetallic Fuel System Tubing with One or More Layers,"1996,
Docket Identification EPA-HQ-OAR-2004-0008-0180.
143. 33 CFR 183.558
144. SAE Surface Vehicle Standard, "Marine Fuel Hoses," Society of Automotive Engineers J 1527, Issued 1985-
12, Revised 1993-02, Docket Identification EPA-HQ-OAR-2004-0008-0177.
145. "Visit to Dyneon on June 12, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-01, June
17, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0208.
146. "Meeting with Avon on June 27, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-01,
August 6, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0207.
147. "Meeting with Avon on June 27, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-01,
August 6, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0207.
5-131
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Draft Regulatory Impact Analysis
148. Akron Rubber Development Laboratory, "Test Report; PN# 49503," Prepared for the U.S. EPA, September 3,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0187.
149. Akron Rubber Development Laboratory, "Test Report PN# 50107" Prepared for the U.S. EPA, December 13,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0184.
150. Akron Rubber Development Laboratory, "Test Report PN# 50108" Prepared for the U.S. EPA, December 13,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0185.
151. Akron Rubber Development Laboratory, "Test Report PN# 53609" Prepared for American Honda Motor
Company, September 26, 2003, Docket Identification EPA-HQ-OAR-2004-0008-0189.
152. Akron Rubber Development Laboratory, "Test Report PN# 53630" Prepared for the U.S. EPA, September 26,
2003, Docket Identification EPA-HQ-OAR-2004-0008-0190.
153. Akron Rubber Development Laboratory, "Test Report PN# 53908" Prepared for the U.S. EPA, October 20,
2003, Docket Identification EPA-HQ-OAR-2004-0008-0191.
154. Email from Mike Fauble, Avon Automotive to Mike Frederick Jr., Avon Automotive, "SAE J30 Test Results,"
April 26, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0394.
155. Fuller, R., "Unique Low Permeation Elastomeric Laminates for Fuel Hose; F200 Technology used in
Automotive Fuel Hose," Hearing Testimony for Dupont-Dow Elastomers on NPRM, October 7, 2002, Docket
Identification EPA-HQ-OAR-2004-0008-0197.
156. "Test Report: 24 hr MicroSHED Test of Fuel Line Assemblies After 8 Week Soak in Fuel C," Testing Services
Group, TSG Report Number L201672-3.1, June 25, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0229.
157. "Test Report: EPA MicroSHED Test on Fuel Line Assemblies 24-Hour EPA MicroSHED Test with Multipoint
@ 8-Weeks," Testing Services Group, TSG Report Number L201672-2.3, June 17, 2002, Docket Identification
EPA-HQ-OAR-2004-0008-0228.
158. "Test Report: EPA MicroSHED Test on Fuel Line Assemblies 24-Hour EPA MicroSHED Re-Test of Part
#01672-11," Testing Services Group, TSG Report Number L201672-3.1R, July 8, 2002, Docket Identification EPA-
HQ-OAR-2004-0008-0230.
159. Akron Rubber Development Laboratory, "Test Report PN# 50107" Prepared for the U.S. EPA, December 13,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0184.
160. Akron Rubber Development Laboratory, "Test Report PN# 50108" Prepared for the U.S. EPA, December 13,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0185
161. Akron Rubber Development Laboratory, "Test Report PN# 52318" Prepared for the U.S. EPA, July 24,2003,
Docket Identification EPA-HQ-OAR-2004-0008-0188.
162. Harold Haskew, "Marine Fuel System Hose Permeation Testing: 2nd Progress Report," Harold Haskew &
Associates, Inc., testing performed at Sterling Performance Testing Laboratory, October 3, 2005, Docket
IdentificationEPA-HQ-OAR-2004-0008-0358.
163. Harold Haskew, "NMMA/EPA Meeting," Harold Haskew & Associates, Inc, presented at NMMA/EPA
meeting on January 24, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0359.
164. Akron Rubber Development Laboratory, "Test Report PN# 52318" Prepared for the U.S. EPA, July 24,2003,
Docket Identification EPA-HQ-OAR-2004-0008-0188.
5-132
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Feasibility of Evaporative Emission Control
165. "Meeting with DuPont and Teleflex on December 10, 2002," memorandum from Mike Samulski, U.S. EPA to
Docket A-2000-02, December 10, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0260.
166. "Low perm marine fuel hose," e-mail from Rob Bentley, Teleflex to Alan Stout U.S. EPA, July 16, 2003,
Docket Identification EPA-HQ-OAR-2004-0008-0225.
167. "SORE Component EO Summary," email from Jim Watson, California Air Resources Board, to Mike
Samulski, U.S. EPA, August 18, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0405.
168. Letter from William Guerry, Kelly Drye Collier Shannon, to Glenn Passavant, U.S. EPA, and Susan Bathalon,
U.S. Consumer Product Safety Commission, "EPA Proposal, Phase III, Small Engine Regulations - Fuel Lines for
Cold Weather Handheld Products," January 25, 2007, Docket Identification EPA-HQ-OAR-2004-0008-0524.
169. Outdoor Power Equipment Institute, "Fuel Hose Design in Relation to the Design and Operation of Handheld
Power Equipment," Presentation to EPA, June 21, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0399.
170. Outdoor Power Equipment Institute, "Comparison of NBR and FPM (Viton) Performance on Hand Held
Equipment," Presentation to EPA, Docket Identification EPA-HQ-OAR-2004-0008-0441.
171. "Alpha List of OEM Approvals," http://www.precixinc.com/oemlist.html, downloaded August 15, 2006,
Docket Identification EPA-HQ-OAR-2004-0008-0411.
172. "Viton: Volume Swell of Viton® Fluoroelastomers in Fuel C / Ethanol Blends," DuPont Performance
Elastomers, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0510.
173. "FKM / Genuine Viton®," http://www.o-ring.info/en/datasheets/fkm-genuine-viton/, downloaded August 15,
2006, Docket Identification EPA-HQ-OAR-2004-0008-0410.
174. Hatano, M., Otsuka, M., Ogata, C., Suetsugu, N, Amemiya, T., Kudo, M., "Development of New FKM O-
Rings with Superior Fuel-Oil Resistance and Low-Temperature Properties," SAE Paper 2005-01-1743, 2005, Docket
Identification EPA-HQ-OAR-2004-0008-043 3.
175. Yamaguchi, Y., Shojima, D., Ogata, C., Oya, K., Kawasaki, K., Kudo, M., "Development of the New FKM O-
Ring for a Cooling Device," 2005-01-1753, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0434.
176. "Technical Information; Dyneon Fluorelastomer LTFE 6400X," 3M, Issued February, 2003, Docket
Identification EPA-HQ-OAR-2004-0008-0521.
177. "Relative Permeation of Elastomers," Precix, downloaded from www.precixinc.com on February 14, 2007,
Docket Identification EPA-HQ-OAR-2004-0008-0525.
178. Balzer, J., "F-TPV: A New Horizon for TPE Technology," Presented by Daikin America to U.S. EPA on
February 14, 2007, Docket Identification EPA-HQ-OAR-2004-0008-0522.
179. Letter from Trevor J. Richards, President Spring Cove Marina, "Fuel Spills While Filling Pleasure Craft
Tanks," April 23, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0383.
180. Letter from Van DePiero, City of Pittsburg, California to Steve Burkholder, Enviro Fill, April 19, 2006, Docket
IdentificationEPA-HQ-OAR-2004-0008-0384.
181. American Boat and Yacht Council, "H-24 Gasoline Fuel Systems," 2005, Docket Identification EPA-HQ-
OAR-2004-0008-0429.
5-133
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Draft Regulatory Impact Analysis
182. Email from Steve Burkholder, Enviro-Fill, to Mike Samulski and Alan Stout, U.S. EPA, "Overfill Prevention
System Developments," July 25, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0447.
183. Boat U.S. Foundation, "Foundation Findings #40; Spill? What Spill?; Products to Keep Fuel Where it
Belongs-In Your Tank," www.boatus.com/foundation/Findings/findings40. March 2005, Docket Identification
EPA-HQ-OAR-2004-0008-0431.
184. Letter from Steve Burkholder, Enviro-Fill, to Mike Samulski, U.S. EPA, March 1, 2006, Docket Identification
EPA-HQ-OAR-2004-0008-0430.
185. Letter from Steve Burkholder, Enviro-Fill, to Mike Samulski, U.S. EPA, January 13, 2006, Docket
IdentificationEPA-HQ-OAR-2004-0008-0446.
186. Email from Steve Burkholder, Enviro-Fill, to Mike Samulski and Alan Stout, U.S. EPA, "Overfill Prevention
System Developments," July 25, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0447.
187. SAE Recommended Practice J30, "Fuel and Oil Hoses," June 1998, Docket Identification EPA-HQ-OAR-
2004-0008-0176.
188. American Society for Testing and Materials, "Standard Test Method for Rubber Property-Effects of Liquids,"
ASTM D 471-06, November 2006, Docket Identification EPA-HQ-OAR-2004-0008-0511.
189. SAE Recommended Practice J1737, "Test Procedure to Determine the Hydrocarbon Losses from Fuel Tubes,
Hoses, Fittings, and Fuel Line Assemblies by Recirculation,"1997, Docket Identification EPA-HQ-OAR-2004-0008-
0178.
190. SAE Surface Vehicle Standard, "Marine Fuel Hoses," Society of Automotive Engineers J 1527, Issued 1985-
12, Revised 1993-02, Docket Identification EPA-HQ-OAR-2004-0008-0177.
191. SAE Surface Vehicle Standard, "Marine Fuel Hoses," Society of Automotive Engineers J 1527, Issued 1985-
12, Revised 1993-02, Docket Identification EPA-HQ-OAR-2004-0008-0177.
192. SAE Surface Vehicle Standard, "Nonmetallic Fuel System Tubing with One or More Layers," Society of
Automotive Engineers J 2260, Issued 1996-11, Docket Identification EPA-HQ-OAR-2004-0008-0180.
193. SAE Surface Vehicle Recommended Practice, "Test Procedure to Determine the Hydrocarbon Losses from
Fuel Tubes, Hoses, Fittings, and Fuel Line Assemblies by Recirculation," Society of Automotive Engineers J 1737,
Issued 1997-08, Docket Identification EPA-HQ-OAR-2004-0008-0178.
194. Draft SAE Information Report J1769, "Test Protocol for Evaluation of Long Term Permeation Barrier
Durability on Non-Metallic Fuel Tanks," Docket Identification EPA-HQ-OAR-2004-0008-0195.
195. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.
196. "Permeation Rates of Small Off Road Engine High-Density Polyethylene Fuel Tanks (April 2001 Testing),
June 8, 2001, California Air Resources Board, Docket Identification EPA-HQ-OAR-2004-0008-0146.
197. "Permeation Rates of High-Density Polyethylene Fuel Tanks (June 2001), June 12, 2001, California Air
Resources Board, Docket Identification EPA-HQ-OAR-2004-0008-0148
198. "Permeation Rates of High-Density Polyethylene Fuel Tanks (May 2001), June 11, 2001, California Air
Resources Board, Docket Identification EPA-HQ-OAR-2004-0008-0149.
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Feasibility of Evaporative Emission Control
199. "Average Permeation Rates of High-Density Polyethylene Off-Road Equipment Fuel Tanks Using a Surface
Area Approach, (March 2002)," March 15, 2002, California Air Resources Board, Docket Identification EPA-HQ-
OAR-2004-0008-0256.
200. Haskew, H., McClement, D., "Fuel Permeation from Automotive Systems; Final Report," prepared for the
California Air Resources Board and the Coordinating Research Council, CRC Project No. E-65, September 2004,
Docket Identification EPA-HQ-OAR-2004-0008-0151.
201. Dickson, A., Goyet, C., "Handbook of Methods for the Analysis of the Various Parameters of the Carbon
Dioxide System in Sea Water; Version 2," Prepared for the U.S. Department of Energy, SOP21 "Applying air
buoyancy corrections," September 29, 1997, Docket Identification EPA-HQ-OAR-2004-0008-0135.
202. Testing Services Group, "CARB TM-513: Portable Fuel Container Permeation Testing," Presented to U.S.
EPA on August 18, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0133.
203. Testing Services Group, "Technical Brief: Buoyancy Correction for Mass Measurement of Fuel Containers,"
TB 50819-1, August 19, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0134.
204. California Air Resources Board, "TP-502: Test Procedure for Determining Diurnal Emissions from Portable
Fuel Containers," proposed July 22, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0300.
205. "Test Method to Measure Fluid Permeation of Polymeric Materials by Speciation," SAE Surface Vehicle
Standard J2659, Issued December 2003, Docket Identification EPA-HQ-OAR-2004-0008-0512.
206. Internal MeadWestvaco memorandum from M. Tschantz to C. Pierson, "Preliminary 3 mm SeaGuard™
Specifications," August 31, 2005, Docket IdentificationEPA-HQ-OAR-2004-0008-0136.
207. "Standard Test Method for Determination of Butane Working Capacity of Activated Carbon," ASTM
International, Designation D5228-92 (Reapproved 2005), Docket Identification EPA-HQ-OAR-2004-0008-0347.
208. Tschantz, M., "Activated Carbon for Use in Marine Evaporative Control Applications," Presented by
MeadWestvaco Corporation at the 2004 International Boatbuilders Exposition, October 25, 2004, Docket
IdentificationEPA-HQ-OAR-2004-0008-0040.
209. "Carbon Specs," email fromM. Tschantz , MeadWestvaco to M. Samulski, U.S. EPA, November 18, 2005,
Docket Identification EPA-HQ-OAR-2004-0008-0421.
210. "Standard Test Method for Ball-Pan Hardness of Activated Carbon," ASTM International, Designation D3802-
79 (Reapproved 2005), Docket Identification EPA-HQ-OAR-2004-0008-0348.
211. "SOP 0960-610 vs. ASTM 3802," email from Mike Tschantz, MeadWestvaco to Mike Samulski, U.S. EPA,
January 13, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0412.
212. Williams, R., Clontz, R., "Impact and Control of Canister Bleed Emissions," SAE Paper 2001-01-0733, 2001,
Docket Identification EPA-HQ-OAR-2004-0008-0432.
213. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
214. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
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Draft Regulatory Impact Analysis
215. Hopf, G., Ries, H., Gray, E., "Development of Multilayer Thermoplastic Fuel Lines with Improved Barrier
Properties," SAE Paper 940165, 1994, Docket Identification EPA-HQ-OAR-2004-0008-0174.
216. Stahl, W., Stevens, R., "Fuel-Alcohol Permeation Rates of Fluoroelastomers, Fluoroplastics, and Other Fuel
Resistant Materials," SAE Paper 920163, 1992, Docket Identification EPA-HQ-OAR-2004-0008-0171.
217. "Visit to Dyneon on June 12, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-01, June
17, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0208.
218. Goldsberry, D., "Fuel Hose Permeation of Fluoropolymers," SAE Paper 930992, 1993, Docket Identification
EPA-HQ-OAR-2004-0008-0173.
219. Tuckner, P., Baker, J., "Fuel Permeation Testing Using Gravimetric Methods," SAE Paper 20001-01-1096,
2000, Docket Identification EPA-HQ-OAR-2004-0008-0160.
220. Fuller, R., "Unique Low Permeation Elastomeric Laminates for Fuel Hose; F200 Technology used in
Automotive Fuel Hose," Hearing Testimony for Dupont-Dow Elastomers on NPRM, October 7, 2002, Docket
Identification EPA-HQ-OAR-2004-0008-0197.
221. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.
222. Duchesne, D., Hull, D., Molnar, A., "THV Fluorothermoplastics in Automotive Fuel Management Systems,"
SAE Paper 1999-01-0379, 1999, Docket Identification EPA-HQ-OAR-2004-0008-0159.
223. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.
224. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.
225. "Visit to Dyneon on June 12, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-01, June
17, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0208.
226. Facsimile from Bob Hazekamp, Top Dog Systems, to Mike Samulski, U.S. EPA, "Permeation of Polyurethane
versus THV Materials @ 60°C," January 14, 2002, Docket A-2000-01, Docket Identification EPA-HQ-OAR-2004-
0008-0435.
227. Duchesne, D., Hull, D., Molnar, A., "THV Fluorothermoplastics in Automotive Fuel Management Systems,"
SAE Paper 1999-01-0379, 1999, Docket Identification EPA-HQ-OAR-2004-0008-0159.
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Costs of Control
CHAPTER 6: Costs of Control
This chapter describes our approach to estimating the cost of complying with the
proposed emission standards. We start with a general description of the approach used to
estimate costs, then describe the technology changes we expect and assign costs to them. We
also present an analysis of the estimated aggregate cost to society.
6.1 Methodology
We developed the costs for individual technologies using estimates from ICF
Incorporated1, conversations with manufacturers, and other information as cited below. The
technology characterization reflect our current best judgment based on EPA's technology
demonstrations, engineering analysis, information from manufacturers, and the published
literature.
Costs of control include variable costs (for incremental hardware costs, assembly costs,
and associated markups) and fixed costs (for tooling, R&D, and certification). Variable costs are
marked up at a rate of 29 percent to account for the engine or equipment/vessel manufacturers'
overhead and profit.2 For technologies sold by a supplier to the engine manufacturers, an
additional 29 percent markup is included for the supplier's overhead and profit. Labor estimates
are marked up by 100 percent to reflect fringe and overhead charges including management,
supervision, general and administrative expenses, etc. All costs are in 2005 dollars.
The analysis presents an estimate of costs that will occur in the first year(s) of new
emission standards and the corresponding long-term costs. Long-term costs decrease due to two
principal factors. First, fixed costs are assessed for five years, after which they are fully
amortized and are then no longer part of the cost calculation. Second, manufacturers are
expected to learn over time to produce the engines with the new technologies or aftertreatment at
a lower cost. Consistent with analyses from other programs, we reduce estimated variable costs
by 20 percent beginning with the sixth year of production.3 The small spark ignited engine
industry and the marine industry have different reasons for the learning.
Learning for the Small SI industry is expected to occur in the catalyst muffler designs. It
will likely occur for two reasons: 1) over time the number of different muffler catalyst designs
may be reduced thereby decreasing substrate costs due to larger ordering volumes. 2) heat shield
manufacturing may become automated and/or designs more uniform. Learning will not occur for
other technologies such as electronic fuel injection systems for they currently exist on some
Small SI equipment and motorized vehicles such as scooters .
In the marine industry, manufacturers are less likely to put in the extra R&D effort for
low-cost manufacturing of engine families of relatively low sales volumes. Learning will occur
in two basic ways. As manufacturers produce more units, they will make improvements in
production methods to improve efficiency. The second way learning occurs is materials learning
where manufacturers reduce scrap. Scrap includes units that are produced but rejected due to
6-1
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Draft Regulatory Impact Analysis
inadequate quality and material scrap left over from the manufacturing process. As production
starts, assemblers and production engineers will then be expected to find significant
improvements in fine-tuning the designs and production processes.
We believe it is appropriate to apply this learning factor here for the marine industries,
given that they are facing new emission regulations, some for the first time, and it is reasonable
to expect learning to occur with the experience of producing and improving emission-control
technologies. Manufacturers do not have significant experience with most of the emissions
controls that are anticipated for meeting the proposed standards.
Many of the engine technologies available to marine and Small SI engine manufacturers
to control emissions also have the potential to significantly improve engine performance. This is
clear from the improvements in automotive technologies. As cars have continually improved
emission controls, they have also greatly improved fuel economy, reliability, power, and a
reduced reliance on regular maintenance. Similarly, the fuel economy improvements associated
with converting from two-stroke to four-stroke engines is well understood. We attempt to
quantify these expected improvements for each type of engine below.
Even though the analysis does not reflect all the possible technology variations and
options that are available to engine manufacturers, we believe the projections presented here
provide a cost estimate representative of the different approaches manufacturers may ultimately
take. We expect manufacturers in many cases to find and develop approaches to achieve the
emission standards at a lower cost than we describe in this analysis.
6.2 Exhaust Emission Control Costs for Small SI Engines
This section presents our cost estimates for meeting the proposed exhaust emission
standards for Small land-based spark-ignition (Small SI) engines.
In 1995, EPA finalized the first regulations for reducing emissions from small spark
ignited (SI) engines <19kW. Small spark ignited engine designs include side valve and overhead
valve engine configurations designated in two groups by engine displacement. Class I engines
are <225cc and Class II engines are >225cc and less than 19kW. The Phase 2 regulations for
these engines were set with the expectation that Class I side valve engines would be converted to
overhead valve design. Certification data from 2005 shows that engine manufacturers have been
able to achieve Phase 2 certification with the continued use of side valve engines in some cases.
A summary of the 2005 technology market mix is presented in Table 6.2-1.
For the proposed Phase 3 standards, Class I engines are estimated to use catalysts and
engine design improvements required to use catalysts safely. For Class II engines, different
technologies were assigned depending on whether the engine was a one cylinder or a multiple
cylinder engine. All one cylinder engines were estimated to use catalysts. For two or more
cylinders, the largest engine family per engine manufacturer was assigned closed loop electronic
fuel injection. The remainder were assigned catalysts with the appropriate muffler setup. The
expected technology market mix is presented in Table 6.2-2.
6-2
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Costs of Control
Table 6.2-1: 2005 Technology Market Mix
sv
OHV
w/ Catalyst
w/ Other (EFI and/or watercooled)
Class I
65%
35%
0.04%
0
Class II
2%
98%
0.2%
2%
Table 6.2-2: Technology Market Mix Expectations for Phase 3 Engines
HC+NOx Emission Standards: 38% Reduction Class I, 34% Reduction Class II
Exhaust Standard Implementation Date
SV
OHV
w/ Catalyst
w/ Other (EFI and/or watercooled)
2012
Class I
65%
35%
100%
0
2011
Class II
2%
98%
72%
28%
The following sections describe the technologies and related variable and fixed costs
followed by an analysis of aggregate costs. The costs are based on a report from ICF
International entitled "Small SI engine Technologies and Costs."4 Variable costs to the
manufacturers vary with the engine size and the emission technologies considered.
Manufacturers prices of all components were estimated from various sources including
information from engine and catalyst manufacturers and previous work performed by ICF
International on spark ignited engine technology. All hardware costs to the engine
manufacturers are subject to a 29 percent mark-up. This includes manufacturer overhead, profit,
dealer overhead and profit. A separate supplier markup of 29 percent is also applied to items
typically purchased from a suppliers such as fuel injection and catalysts. A 5 percent warranty
mark-up is added to hardware cost of specific technologies including electronics, to represent an
overhead charge covering warranty claims associated with new parts.
Fixed costs to the manufacturer include the cost of researching, developing and testing a
new technology. The cost of retooling the assembly line for the production of new parts as well
as engine certification including durability testing are also fixed costs. Design and
development fixed costs per month are listed in Table 6.2-3. Tooling and specific R&D costs are
listed in the following sections. Fixed costs for certification are listed in Section 6.2.3.
Table 6.2-3: Design and Development Costs
for use in Fixed Cost Estimates per Month 5
6-3
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Draft Regulatory Impact Analysis
Hours
Rates
Costs
Design Costs Per Month
Engineer
160
$64.41
TOTAL Design Costs Per Month
$10,306
$10,306
Development Costs Per Month
Engineer
Technicians
Dynamometer Test
Time
160
320
20 tests
$64.41
$41.87
$250 ea
TOTAL Development Costs Per Month
$10,306
$13,398
$5,000
$28,704
6.2.1 Class I
Class I engines currently emitting at or below the Phase 2 emission standard of 16.1
g/kWh will need to reduce their engine out HC+NOx emissions by 30-50 percent to comply with
the proposed Phase 3 emission standard of 10 g/kWh with an appropriate margin. A number of
Class I side valve (SV) engines have been redesigned for the Phase 1 and Phase 2 rulemakings,
however SV and overhead valve (OHV) engines will need a different approach to meet these
emission standards. One technology to reduce emissions to the Phase 3 levels is a three way
catalyst with appropriate precious metal loading for minimal CO conversion. EPA work has
shown that catalysts can function effectively through a dynamometer aging of 125 hours with a
catalyst conversion of about the same amount at high hours as low hours6. The amount of
conversion is only constrained by 1) the size of the catalyst to fit in the existing, or slightly
larger, muffler, 2) residence time of the exhaust gas along with 3) muffler surface and exhaust
gas temperature issues with respect to the amount of CO converted within a catalyst. EPA's
work has been shown to convert HC+NOx within a range of 3.8-6.7 g/kW-h (median approx
5.7g/kW-h) on OHV engines and 3.8-10.3 g/kW-h on SV engines (median of 6.8 g/kW-h).
EPA's Phase 2 certification database lists OHV and SV engine HC+NOx emission levels
at low hours, a deterioration factor (df) and resultant certification levels. Engine manufacturers
with most regulated experience were considered for these df ranges. Engine families using
credits to certify to the emission standard with ABT were not included.
6-4
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Costs of Control
Table 6.2-4: 2005 EPA Certification Database with Catalyst Assumptions7
Technology
Type/UL
SV/125
OHV/125
OHV/250
OHV/500
Engine Out
"zero
hours"
(Min-Max)
10-11
6-15
7-15
8-14
DF
(Min-Max)
1-1.24
1-1.356
1-1.136
1-1.161
Certification
Level
(Min-Max)
13-14
9-16
8-12
8-15
Catalyst
conversion
(median
from EPA
work)
6.8
5.7
5.7
5.7
Engine with Catalyst
6.2-7.2
3.3-10.3
2.3-6.3
2.3-9.3
Table 6.2-4 is based on median HC+NOx catalyst conversion from EPA test work in the
Safety Study.8 The Safety Study also shows improvements in the cooling system design will
provide cooling to the engine and/or catalyst muffler system for reduced muffler skin
temperatures. Individual engine family applications will vary and engine improvements may be
required for durable and effective catalyst operation.
6.2.1.1 Engine Improvements for Class I
Improvements in engine combustion efficiency and engine cooling will assure the engine
systems support catalyst durability. Engine improvements for durable catalyst operation include
changes that are fixed costs and variable costs. Improvements in engine systems resulting in
fixed costs potentially include the following: 1) improved combustion chamber design for
optimized combustion, 2) improved piston design for reduced crevice volumes and reduced HC
emissions, 3) improved machining and casting tolerances for all combustion chamber
components, 4) improved cylinder head fin design for improved cooling, and 5) improved
carburetion for fuel delivery and system durability. Some engines would also benefit greatly
from 6) improved flywheel design in order to provide additional cooling to the engine and
muffler system. Clearly not all engines need these upgrades and many will implement few or
none.
Fixed costs per engine family for engine improvements are estimated at four months of design
work (one engineer) and six months of development work (one engineer, one technician and
dynamometer test time) along with tooling costs for the cylinder head, piston, connecting rod,
camshaft, carburetor, flywheel and setup changes. Tooling costs are estimated to be the same
across engine useful life categories with the exception of Class 1125 hour SV engines which
contains some engine families that are sold in much larger volumes and therefore would have
more tools to be modified. These fixed costs are presented in Table 6.2-5.
6-5
-------
Draft Regulatory Impact Analysis
Table 6.2-5: Fixed Costs for Engine Improvements for Class I9
Engine Class
Useful life (his)
Valving
Class I
125
SV
125,250,500
OHV
R&D
Design (4 months)
Development (6 months)
TOTAL R&D per Engine Line
41,225
172,225
213,450
41,225
172,225
213,450
TOOLING COSTS
Cylinder Head
Piston
Connecting Rod
Camshaft
Carburetor
Flywheel
Setup Changes
TOTAL TOOLING per Engine Line
TOTAL FIXED
50,000
50,000
30,000
16,000
120,000
70,000
150,000
486,000
$699,450
25,000
25,000
15,000
8,000
60,000
35,000
75,000
243,000
$456,450
Variable cost items were identified from EPA field aging of engines from several engine
manufacturers. EPA performed several lawnmower in-use test programs in 2003 to 2005.
Several of the SV and OHV engines were equipped with catalysts. The process revealed that
potentially several engine design characteristics needed improvement in some cases in order for
catalysts to be successfully applied in-use. Items included: 1) fuel filter to screen out impurities
(assure do not encounter a stuck float and thereby excessive fuel flowed through the engine
coating the catalyst and rendering it inactive.), 2) incorporation of an intake gasket to assure
leaks do not develop in the intake system thereby resulting in hot engine operation and a number
of engine operational issues, 3) engine shroud screen over fan (avoid debris collecting in the
engine fan), and 4) improved engine cooling system for SV engines to assure the engine's piston
and combustion chamber walls stay in contact so oil does not seep past the rings and into the
combustion chamber (see Chapter 4) thereby potentially poisoning the catalyst. Lastly, the
incorporation of improved induction coils will reduce the opportunity for spark plug wire
failures and misfire events. Table 6.2-6 lists the variable costs for engine improvements for
Class I engines certified to various useful lives. Clearly not all engines need these upgrades to
succeed and many will implement few or none.
6-6
-------
Costs of Control
Table 6.2-6: Variable Costs for Engine Improvements for Class I
10
Engine Improvement
Fuel Filter Screens (80% of engine sales)
cost/engine: 0.02
Improved Intake Gaskets (75% of engine sales for
Class I 125 hour useful life)
cost/engine: 0.03
Screen over cooling fan (16% of 125 hr Class I)
cost/engine: 0.45
Larger Induction Coils (all)
Engine Manufacturer Cost
TOTAL w/Markup
29% OEM
Learning Curve w/ 29% Markup
(0.8*Total w/Markup)* 1.29
UL 125
SV
0.02
0.02
0.07
0.10
0.21
0.27
0.22
UL 125
OHV
0.02
~
0.07
0.10
0.19
0.24
0.19
UL250
0.02
~
~
0.10
0.12
0.15
0.12
UL500
~
~
~
0.10
0.10
0.13
0.10
6.2.1.2 Catalysts for Class I
The following paragraphs describe details on catalysts substrates, washcoat and precious
metal, and muffler shielding for Class I engines. Although commonly in use today, spark
arresters are discussed in the context of the overall design.
Based on catalyst/muffler development and emission testing by EPA (2004-2005), an
engine which has an HC+NOx exhaust ratio of 60/40 is best suited for the use of a catalyst in
Small SI engines for the catalyst can be designed for minimal CO oxidation and related heat
generation. This ratio can be found on OHV engines for they have efficient combustion
chambers. SV engines require slightly larger catalysts due to their less efficient combustion
chambers and less than optimum HC/NOx ratios. In addition, SV engines are more likely to
have oil seep past the piston rings due into the exhaust to cylinder distortion. A longer catalyst,
or the use of a pipe catalyst prior to the brick catalyst, allows it to survive for the full useful life
for the catalyst is poisoned from the front of the catalyst to the back. According to the EPA
Phase 2 certification database, Class I SV engine families are certified to the 125 hour useful life
and therefore the cost analysis includes two different catalyst costs for the 125 hour useful life.
The engines certified to the 250 and 500 useful life categories are all of OHV engine
design. As with the 125 hour category, catalyst substrate sizes are calculated as a percentage of
the engine displacement. The certification database was queried for this engine displacement
data and the displacements are sales weighted, as seen in Table 6.2-7. Catalyst volumes range
6-7
-------
Draft Regulatory Impact Analysis
from 18 percent of the engine displacement for the 125 OHV useful life to 50 percent of the
engine displacement for the 500 hour useful life. Larger catalysts are needed for longer useful
life periods in order to provide the emission conversion durability. Specific costs for engines
within each useful life category will differ.
The substrate cost is based on an average cost of metallic and ceramic substrates as
presented in the ICF report11 due to the variety of Small SI equipment types and variety of
catalysts offered in the marketplace. This cost analysis estimatess equal weighting of the
substrate types and therefore takes an average of the cost for both metallic and ceramic.
Due to the concern of oil sulfur poisoning in Class I engines, EPA envisions that a 5:1
ratio of Platinum/Rhodium precious metal would be used for these catalysts. The cost of
precious metals was taken from a 3 year average in price from 2003-2005. Washcoat material is
expected to be a 30%/70 percent mixture of cerium and alumina oxide, respectively.
The design of the catalyst/muffler forms the basis for the degree of cooling needed at the
muffler and exhaust port. EPA's solution for muffler surface and exhaust gas cooling included
three steps 1) forcing the cooling air from the engine fan/cylinder head region to the muffler can
be achieved through a slight redesign of the engine's shroud, 2) a muffler shroud that is designed
to guide the cooling air around the entire muffler and exits at a specified location, and lastly 3)
and if when needed an ejector is added to the muffler at the exhaust gas outlet so the exhaust gas
can be combined with ambient air before being accessible to the user.
EPA's observation of a number of lawnmower engine designs revealed that the majority
of heat shields currently used on small engines need to be redesigned in order to allow the use of
air flow from the engine's fan to flow optimally around the muffler for cooling. The portion of
engines that do have such systems and will not incur this cost were removed from the cost
analysis and ICF's estimates for this technology were adjusted. EPA utilized the 2005
certification database to estimate sales and to calculate a percentage of engines that will be
estimated to redesign their muffler heat shield. Table 6.2-7 contains the variable costs for
catalysts, heat shields and spark arresters.
-------
Costs of Control
Table 6.2-7: Variable Catalyst Costs for Class I12
to Achieve Proposed Phase 3 Standards
Useful Life
Engine Power (hp)
Engine Displacement (cc)
Catalyst Volume (cc)
Substrate Diameter (cm)
Substrate
Washcoat and Precious
Metal
Labor
Labor Overhead 40%
Supplier Markup 29%
Catalyst Manufacturer Price
Heat Shield*
Spark Arresters
Engine Manufacturer Cost
TOTAL w/Markup
29% OEM
UL125
SV
3.3
178
45
3.50
$1.97
$1.83
$1.40
$0.56
$1.67
$7.43
$0.50
$0.05
$7.98
$10.29
UL125
OHV
5.1
180
32
3.50
$1.53
$1.31
$1.40
$0.56
$1.39
$6.19
$0.29
$0.05
$6.53
$8.42
UL250
5.0
167
55
4.00
$2.32
$2.81
$1.40
$0.56
$2.06
$9.15
$0.18
$0.05
$9.38
$12.10
UL500
5.2
166
83
4.50
$3.22
$4.24
$1.40
$0.56
$2.73
$12.15
$0.14
$0.05
$12.34
$15.92
* Based on EPA's work with small engine equipment from 2003-2005, it has been observed that
some manufacturers have heat shielding that is sufficient or only needs slight modification.
These sales volumes have been removed and the resultant price recalculated.
The fixed costs related to catalyst development for Class I engine applications include
design (one engineer), of two months, and development (one engineer, one technician and
dynamometer time), for five months, of the muffler and heat shield. The inside of the muffler is
to be redesigned to house the catalyst, provide supplemental air when needed, and provide
baffling for the exhaust flow in order to maximize heat dissipation from the exhaust flow. The
muffler stamping will also need to be updated to account for the new design. A second critical
component of the catalyst/muffler system is the heat shield. The heat shield must be designed to
allow cooling air from the fan to flow around the muffler to maximize cooling of the muffler and
then exit at an optimum point. The muffler/heat shield system must be located at a
predetermined distance from the engine block in order to allow air to flow behind the muffler to
cool the backside. Setup changes also are incurred with these modified stampings. The total
tooling per engine line is estimated at $240,000 for Class I engines of 125 hour useful life and
6-9
-------
Draft Regulatory Impact Analysis
$120,000 for Class I engines of other useful life periods. The difference is due to the additional
tooling for high volume SV engine families. Table 6.2-8 presents the fixed costs associated with
using catalysts on Class I engines.
Table 6.2-8: Fixed Costs for Catalysts for Class I Engines
13
Engine Class
Useful life (hrs)
Valving
Class I
125
SV
125, 250, 500
OHV
R&D
Design
(2 months)
Development (5 months)
TOTAL R&D per Engine Line
20,612
143,521
164,133
20,612
143,521
164,133
TOOLING COSTS
Modified Muffler Stamping
Heat Shield Stamping
Engine Shroud Modification
Setup Changes
TOTAL TOOLING per Engine Line
TOTAL FIXED COSTS
100,000
60,000
30,000
50,000
240,000
$404,133
50,000
30,000
15,000
25,000
120,000
$284,133
A learning curve of 20 percent is applied to costs for catalyst technology starting in the
sixth year after the standard is implemented. This somewhat conservative since the learning
normally occurs at 20 percent with a doubling of production which would thus be in the third or
fourth year. Optimized catalyst/muffler designs and manufacturing processes will likely be
developed as the industry becomes experienced in using mufflers with catalysts on Small SI
engines. The muffler washcoat will still be unique per engine family per engine manufacturer
for engine out emissions will differ. Table 6.2-9 presents the estimated learning curve impacts
on variable costs. The precious metal prices are determined in the marketplace and therefore
would not be affected by the learning curve.
6-10
-------
Costs of Control
Table 6.2-9: Learning Curve Variable Catalyst Costs for Class I
to Achieve Proposed Phase 3 Standards
Useful Life
Engine Power (hp)
Engine Displacement (cc)
Catalyst Volume (cc)
Substrate Diameter (cm)
Substrate
Washcoat and Precious
Metal
Labor
Labor Overhead
Supplier Markup 29%
Manufacture Price
Heat Shield
(adjusted % for eng w/
sufficient heat shield)
Flame/Spark Arrester
Hardware Cost to
Manufacturer
w/Markup
29% OEM
UL 125
-SV
3.3
178
45
3.50
$1.57
$1.83
$1.40
$0.56
$1.55
$6.92
$0.40
$0.05
$7.37
$9.50
UL 125
-OHV
5.1
180
32
3.50
$1.22
$1.31
$1.40
$0.56
$1.30
$5.80
$0.23
$0.05
$6.08
$7.84
UL250
5.0
167
55
4.00
$1.86
$2.81
$1.40
$0.56
$1.92
$8.55
$0.14
$0.05
$8.74
$11.28
UL500
5.2
166
83
4.50
$2.58
$4.24
$1.40
$0.56
$2.55
$11.32
$0.11
$0.05
$11.49
$14.82
Table 6.2-10 contains the estimated total costs for Class I Phase 2 compliant engines to
meet the Phase 3 emission standards. Near term costs are those costs for the first five years.
Long term costs are those costs to which the learning curve has been applied.
6-11
-------
Draft Regulatory Impact Analysis
Table 6.2-10: Class I Estimated Total Costs Per Engine (Variable) and
Per Engine Family (Fixed) to Achieve Proposed Phase 3 Standards
Useful Life
Engine Displacement (cc)
Catalyst Volume (cc)
Substrate Diameter (cm)
UL 125 -
SV
178
45
3.50
UL 125 -
OHV
180
32
3.50
UL250
167
55
4.00
UL500
166
83
4.50
Variable Costs - Near Term
Engine Improvements
Catalyst
Total Variable Cost (Near)
$0.27
$10.29
$10.56
$0.24
$8.36
$8.60
$0.15
$12.10
$12.25
$0.13
$15.92
$16.05
Variable Costs - Long Term (with Learning)
Engine Improvements
Catalyst
Total Variable Cost (Long)
$0.22
$9.50
$9.72
$0.19
$7.84
$8.04
$0.12
$11.28
$11.39
$0.10
$14.82
$14.92
Fixed Costs
Engine Improvements
Catalyst
Total Fixed Costs
$699,450
$404,133
$1,103,583
$456,450
$284,133
$740,583
$456,450
$284,133
$740,583
$456,450
$284,133
$740,583
6.2.2 Class II
The proposed Phase 3 HC+NOx emission standard for Class II is 8 g/k-Wh which is a 34
percent emission reduction from the Phase 2 standards of 12.1 g/k-Wh. This standard is to be
met at the end of the regulatory useful life for each engine family. The EPA Phase 2 certification
database shows that the majority of engines in this Class are of OHV design however,
approximately 2 percent of the engines are still side valve engine technology.
Class II side valve engines are currently certified to the Phase 2 standards with credits
from lower emitting OHV engines. The EPA 2005 certification database shows he majority of
overhead valve engines currently certifying HC+NOx at a range of 7-11 g/kW-h and side valve
engines certifying in the range of 13-20 g/kW-h. Lowering of the emission standard will reduce
the number of emission credits available for side valves to certify and therefore, it is assumed
that the remaining side valve engines will be phased out and replaced with currently produced
overhead valve engines or continue to be certified using ABT credits from a limited number of
6-12
-------
Costs of Control
lower emitting engine families.
Assuming a 2 g/kW-h compliance margin to 6 g/kW-h, emission reduction technologies
will need to be designed to reduce emissions 15-45 percent. Table 6.2-11 illustrates potential
engine out emissions with emission reduction technologies applied to Phase 2 engines. OHV
engines are expected to potentially include some engine improvements and/or catalysts or
electronic fuel injection.
Table 6.2-11: 2005 EPA Certification Database Summary With Catalyst Assumptions14
UL
OHV
250
500
1000
Engine Out
"zero hours"
(Min-Max)*
4.8-10.0
Median: 7.9
4.4-10.8
Median: 8.3
6.0-11.2
Median: 8.4
DF
(Min-Max)**
1-1.7
Median: 1.137
1-1.6
Median: 1.039
1-1.4
Median: 1.03
Certification
Level
(Min-Max)*
6.7-12.0
Median: 8.9
5.9-10.9
Median: 9.5
6.9-11.2
Median: 8.9
Catalyst
conversion
(non-EFI
engine)15
4.0
4.0
4.0
Engine with Catalyst
(Based on Median
values)
2.7-8.0
1.9-6.9
2.9-7.2
* Values of engines that meet the standard. 500 hr UL has a liquid cooled engine with catalyst that meets
a 2.6 g/kW-h HC+NOx and 1000 hr UL has the same that meets 1.8 g/kW-h HC+NOx.
**Some engines have catalysts and therefore claim a higher df
Class II contains several liquid cooled engines. These engines likely have the ability to
be enleaned to more of a degree due to the additional cooling assistance and therefore may not
need a catalyst to meet the Phase 3 proposed emission standards.
6.2.2.1 Engine Improvements for Class II
Engine improvements include improved engine design and larger induction coils as
shown in Tables 6.2-12 and 6.2-13. Improvements in engine design will allow for more efficient
combustion and a more favorable HC:NOx ratio for the use of a reducing catalyst. A larger
induction coil will reduce the opportunity for spark plug wire failure and misfire events. It is
estimated that 1000 hour engines currently have sufficient induction coils and will not need this
improvement.
6-13
-------
Draft Regulatory Impact Analysis
Table 6.2-12: Variable Costs for
Engine Improvements for Class II per Engine16
Larger Induction Coils
TOTAL
w/Markup 29% OEM
Learning w/29% OEM
(0.8*Total)*1.29
UL250
0.09
0.12
0.10
UL500
0.09
0.12
0.10
UL 1000
~
~
~
Improved engine design includes machining and casting tolerances, improved
combustion chamber configuration, reduced crevice volumes, better cooling (improved fin
design on cylinder head and oil control), improved flywheel design and improved carburetion.
Better carburetor performance is needed to assure floats do not stick and better cooling so
engines operate at cooler temperatures. Fixed costs include design (one engineer at 4 months),
development and tooling costs (one engineer, one technician and dynamometer time for 6
months) per engine family to achieve improved engine design. Projected fixed costs are
presented in Table 6.2-13. The fixed cost is estimated to be the same per engine family and is
estimated at $456,450.
6-14
-------
Costs of Control
Table 6.2-13: Fixed Costs for
Engine Improvements for Class II per Engine Family17
Engine Class
Useful life (hrs)
Valving
Class II
250,500,1000
OHV
R&D
Design (4 months)
Development (6 months)
TOTAL R&D per Engine Line
41,225
172,225
213,450
TOOLING COSTS
Cylinder Head
Piston
Connecting Rod
Camshaft
Carburetor
Flywheel
Setup Changes
TOTAL TOOLING per Engine Line
TOTAL FIXED
25,000
25,000
15,000
8,000
60,000
35,000
75,000
$243,000
$456,450
6.2.2.2 Catalysts for Class II
Further emission reduction can be achieved through the use of catalysts. The catalyst
must be designed for durability throughout the engine's regulatory useful life. A catalyst
efficiency of 25-45 percent is estimatedd for these engines. The catalyst technology that would
be utilized would be similar to that used for Class I engines. The exceptions include 1) Class II
engines would not use supplemental air because the HC and NOx ratios are more favorable in
Class II OHV engines due to their more efficient combustion chamber and larger displacement
and horsepower, and 2) the precious metals in the catalysts range from
platinum/palladium/rhodium for 250 and 500 hour Class II engines to to palladium/rhodium
(5:1) for 1000 hour regulatory useful life engines.
Class II engine designs include engines 1 to 4 cylinders. Engines with two or more
cylinders have specific issues to be considered in terms of safety with regard to engine exhaust
and catalyst use and this will be addressed towards the end of this section. The variable costs for
6-15
-------
Draft Regulatory Impact Analysis
catalysts of single cylinder engines are listed in Table 6.2-14. The catalyst substrate size is
calculated based on the engine displacement size. To utilize one value per regulatory useful life
category for this analysis, the engine horsepower and displacements were sales weighted with
values from the 2005 EPA certification database information. Catalyst volumes range from 33
percent of the engine displacement for the 250 useful life to 50 percent of the engine
displacement for the 1000 hour useful life. Larger catalysts are needed for longer useful life
periods in order to provide the emission conversion durability.
Catalyst substrate and heat shield variable costs will be decreased in the sixth year with a
learning curve of 20 percent. This somewhat conservative since the learning normally occurs at
20 percent with a doubling of production which would be in the third or fourth year. Optimized
catalyst/muffler designs and heat shield manufacturing processes will likely be developed as the
industry becomes experienced in application of the catalyst technology across their product line.
The muffler washcoat will likely still be unique per engine family per engine manufacturer and
therefore it is estimated there will likely not be a one size fits all catalyst/muffler design. The
precious metal prices are determined in the marketplace and therefore are not discounted over
time.
6-16
-------
Costs of Control
Table 6.2-14: Variable Catalyst Costs for Class II OHV Single Cylinder Engine
HC+NOx Emission Reduction to Phase 3 Standards
Useful Life
Engine Power (hp)
Engine Displacement (cc)
Catalyst Volume (cc)
Substrate Diameter (cm)
Substrate*
Washcoat and Precious Metal
Labor
Labor Overhead 40%
Supplier Markup 29%
Manufacture Price
Heat Shield
Spark Arrester
Hardware Cost to Manufacturer
w/Markup 29% OEM
Near Term Estimates
250
11.3
406
134
5.25
$4.78
$4.03
$1.40
$0.56
$3.12
$13.89
$4.23
$0.10
$18.22
$23.50
500
11.1
338
135
6.00
$4.81
$2.73
$1.40
$0.56
$2.75
$12.25
$3.96
$0.05
$16.26
$20.97
1000
9.5
329
165
7.00
$5.67
$4.10
$1.40
$0.56
$3.40
$15.13
$4.05
$0.05
$19.23
$24.80
Learning Curve Estimates
250
11.3
406
134
5.25
$3.82
$4.03
$1.40
$0.56
$2.84
$12.65
$3.38
$0.10
$16.14
$20.82
500
11.1
338
135
6.00
$3.84
$2.73
$1.40
$0.56
$2.47
$11.00
$3.17
$0.05
$14.23
$18.35
1000
9.5
329
165
7.00
$4.53
$4.10
$1.40
$0.56
$3.07
$13.66
$3.24
$0.05
$16.95
$21.87
* 50/50- split of metallic vs ceramic substrates
Fixed costs involve modification to the existing heat shield and cooling system. If the
muffler is in close proximity to the engine fan then cost for a heat shield can also be included
because in some cases the heat shields will need to be improved in order to direct cooling air
from the engine's flywheel over the muffler for muffler cooling. These fixed costs are presented
in Table 6.2-15.
6-17
-------
Draft Regulatory Impact Analysis
Table 6.2-15: Fixed Costs for Class II OHV Single Cylinder Engine
Engine Class
Useful life (hrs)
Valving
II
125, 250, 500
OHV
R&D
Design
(2 months)
Development (5 months)
TOTAL R&D per Engine Line
20,612
143,521
164,133
TOOLING COSTS
Modified Muffler Stamping
Heat Shield Stamping
Engine Shroud Modification
Setup Changes
TOTAL TOOLING per Engine Line
TOTAL FIXED COSTS
50,000
30,000
15,000
25,000
120,000
$284,133
Carbureted V-Twins
Carbureted engines with more than one cylinder, ex: V-twins or more, have special
concerns when considering the use of catalyst application. Multi-cylinder engines may continue
to run if one cylinder misfires or does not fire at all. If this occurs, the results is raw unburned
fuel and air from one cylinder and hot exhaust gases from the other cylinder combining in the
muffler. In a catalyst muffler, this condition will likely result in continuous backfire which
would create high temperatures within the muffler and potentially destroy the catalyst. One
solution is to have separate catalyst mufflers for each cylinder. The two cylinders in the V-twins
currently share one muffler. If two mufflers are used, then the individual mufflers would likely
need to be slightly larger. Each individual muffler would need to be 25-30 percent larger than
one half the volume of the original. Since the two cylinders in the V-twins currently share one
muffler one option for consideration would be to package the two catalysts in separate chambers
within one larger muffler.
Costs for this new muffler design are listed in Tables 6.2-16 and 6.2-17. V-twin engines
from EPA's certification database were sales weighted for power and engine displacement per
regulatory useful life. ICF provided the estimates for existing muffler costs and new muffler
cost estimates.
18
6-18
-------
Costs of Control
Table 6.2-16: Variable Costs for Change to Two Mufflers for V-Twins
19
Engine Power (hp)
Engine Displacement - Total (cc)
Per Cylinder Displacement (cc)
Current Muffler Cost
New Muffler Cost (includes 2)
Hardware Cost to Manufacturer
OEM Markup @ 29%
Total Component Costs
250 OHV
16.3
605
393
($20.24)
$26.31
$6.07
$1.76
$7.83
500 OHV
20.1
632
411
($23.13)
$30.07
$6.94
$2.01
$8.95
1000 OHV
17.1
627
408
($22.57)
$29.34
$6.77
$1.96
$8.73
Fixed costs include modified muffler stamping, exhaust pipe changes and setup changes.
These costs are estimated at $100,000 per engine family. Special considerations were not
accounted for in the case where OEM's obtain their own muffler and assemble the muffler onto
the engine once the engine is received from the engine manufacturer. This analysis considers
that in most cases equipment manufacturers would buy their catalyst mufflers from the engine
manufacturer in order to avoid engine certification.
Table 6.2-17: Fixed Costs for Change to Two Mufflers for V-Twins2
Engine Power
Engine Displacement - Total (cc)
Per Cylinder Displacement
Modified Muffler Stamping
Exhaust Pipe Changes
Setup Changes
Total Tooling per Engine Line
250 OHV
16.3hp
605
393
$50,000
$25,000
$25,000
$100,000
500 OHV
20.1hp
632
411
$50,000
$25,000
$25,000
$100,000
1000 OHV
17.1hp
627
408
$50,000
$25,000
$25,000
$100,000
In this analysis, catalyst sizes are related to the engine cylinder size and therefore since
cylinders of V-twin engines are smaller than one cylinder Class II engines, costs are recalculated
from Table 6.2-14. Note that one catalyst is used in each muffler for a total of two catalysts.
Tables 6.2-18 and 6.2-19 present the projected variable and fixed catalyst costs for Class II OHV
V-twin engines.
6-19
-------
Draft Regulatory Impact Analysis
Table 6.2-18: Variable Catalyst Costs for Class II OHV V-Twin Engine,
Near Term and Learning Curve Effect
Useful Life
Engine Power (hp)
Engine Displacement per Cylinder
Catalyst Volume (cc)
Substrate Diameter (cm)
Substrate*
Washcoat and Precious Metal
Labor
Labor Overhead 40%
Supplier Markup 29%
Manufacture Price per Catalyst
Two Catalysts ($x2)
Heat Shield (2)
Spark Arrester (2)
Hardware Cost to Manufacturer
Markup
29% OEM
New Muffler Differential
TOTAL COST
Near Term Costs
250
16.3
303
100
5.00
$3.74
$3.00
$1.40
$0.56
$2.52
$11.22
$22.45
$8.53
$0.20
$31.18
$9.04
$7.83
$48.05
500
21.0
316
126
5.00
$4.55
$2.55
$1.40
$0.56
$2.63
$11.68
$23.36
$9.76
$0.10
$33.22
$9.63
$8.95
$51.80
1000
17.1
314
157
5.50
$5.44
$3.91
$1.40
$0.56
$3.28
$14.59
$29.18
$10.50
$0.10
$39.79
$11.54
$8.73
$60.06
Learning Curve Effect
250
16.3
303
100
5.00
$2.99
$3.00
$1.40
$0.56
$2.31
$10.26
$20.52
$6.82
$0.20
$27.54
$7.99
$6.26
$41.97
500
21.0
316
126
5.00
$3.64
$2.55
$1.40
$0.56
$2.36
$10.51
$21.02
$7.81
$O.10
$28.92
$8.39
$7.16
$44.76
1000
17.1
314
157
5.50
$4.35
$3.91
$1.40
$0.56
$2.96
$13.19
$26.37
$8.4
$0.1
$34.87
$10.11
$6.98
$51.97
* 50/50- split of metallic vs ceramic substrates
6-20
-------
Costs of Control
Table 6.2-19: Fixed Costs for Class II OHV V-Twin Engine
Useful Lives
250, 500, 1000
R&D COSTS
Design (2 months)
Development (5 months)
TOTAL R&D
$20,612
$143,521
$164,133
TOOLING COSTS
Heat Shield Stamping
Engine Shroud Modification
Setup Changes
New Muffler Design
Total Tooling per Engine Line
TOTAL FIXED COSTS
$50,000
$25,000
$25,000
$100,000
$200,000
$364,133
Electronic Fuel Injection
Electronic fuel injection (EFI) is another solution for engines with two or more cylinders.
EFI will allow more equal fuel delivery between or among the engine cylinders. In addition, it
enables better atomization and more efficient fuel delivery during load pickup. If an engine
family is somewhat close to the Phase 3 standard currently then EFI may allow the engine to
meet the emission standards without a catalyst. If a small catalyst is needed, EFI allows the
engine to be setup for cylinder monitoring and can be shut down if all cylinders are not operating
properly. Due to the anticipated higher cost for EFI compared to catalyst, EPA estimates that
each engine manufacturer will initially apply EFI to the engine family, of two or more cylinders,
with the highest sales volume. Table 6.2-20 lists the estimated costs to apply electronic fuel
injection. The cost tables include subtracting the existing carburetor.
6-21
-------
Draft Regulatory Impact Analysis
Table 6.2-20: Variable Costs for Electronic Fuel Injection - Open and Closed Loop
For Class II Engines and Applications with a Battery21
Injectors
Pressure Regulator
ECM/MAP Sensor
Throttle Body
Air Temperature Sensor
Fuel Pump
Oxygen Sensor
Wiring/Related Hardware
HARDWARE COST TO MANUFACTURE
OEM markup @ 29%
Warranty Markup @ 5%
Total Component Cost
Remove existing carburetor ($15) marked up 29%
EFI Technology Difference
Open Loop EFI
8.00
3.75
27.00
2.75
1.50
10.50
~
12.00
66.75
19.36
2.85
88.96
-19.35
$69.61
Closed Loop EFI
8.00
3.75
27.00
2.75
1.50
10.50
7.00
12.00
73.75
21.39
3.69
98.83
-19.35
$79.48
Fixed costs for electronic fuel injection are listed in Table 6.2-21. Open loop fuel
injection requires more research and development time due to the fact that it does not use an
oxygen sensor to keep the air/fuel ratio in check. This analysis estimatess all engines using
electronic fuel injection will be developed as closed loop fuel injection systems.
6-22
-------
Costs of Control
Table 6.2-21: Fixed Costs for Electronic Fuel Injection - Open and Closed Loop
For Class II Engines and Applications with a Battery
Design
Development
Modified Exhaust Manifold for O2 Sensor
Total Fixed Costs
Open Loop
$41,225
$229,633
—
$270,858
Closed Loop
$20,612
$57,408
$25,000
$103,020
6.2.2.3 Equipment Costs
The majority of Class I engines are sold as a unit and therefore the engine, fuel tank and
muffler are provided by the engine manufacturer to the equipment manufacturer. As shown in
EPA's Technical Study on the "Safety of Emission Controls for Nonroad Spark-Ignition Engines
<50 Horsepower", catalysts can be applied to Class I engines such that muffler temperatures are
equal to or less than those of the current Phase 2 product with minimal changes to the engine
package. Some engines may require larger mufflers to house a catalyst depending on current
muffler design. However the majority of equipment housing Class I engines are close coupled to
the engine with open access for air cooling and therefore it no equipment redesign costs are
applied to equipment manufacturers.
The majority of Class II engines are not sold as a unit. The current industry practice
includes equipment manufacturers purchasing the muffler separate from the engine. Based on
conversations with industry it is believed that for several reasons this practice will change to the
dominant practice being the equipment manufacturer purchasing the muffler from the engine
manufacturer. The offerings by the engine manufacturer will likely be influenced by the largest
customers and smaller equipment manufacturers will have a few set models from which to
choose. A limited amount of equipment redesign will be required on products.
EPA's work with catalysts in mufflers of two one-cylinder Class II lawn tractor engines
has revealed that the current muffler on this equipment type has plenty of room to accommodate
the catalyst and internal baffling to promote cooling of the exhaust gases. Smaller mufflers are
used in other applications in which engine noise is not of concern. EPA did not work with these
mufflers and therefore, it is uncertain if the catalyzed muffler will work in these mufflers. It is
possible that a larger muffler can may be required to accommodate the catalyst.
Changes that will be required on Class II engines with catalysts includes a heat shield for
the muffler (counted in catalyst costs), necessary sheet metal to direct cooling from the engine
flywheel to the muffler and any equipment design changes to accommodate a different engine
envelope.
Incorporating shrouding to direct the cooling air to and around the muffler is of most
6-23
-------
Draft Regulatory Impact Analysis
importance. The shrouding added includes extending and rerouting some of the engine sheet
metal that is used to direct the air-flow out of the engine cylinder and blocking off the usual air
exit into the engine compartment. The air is routed out the bottom of the chassis instead. In
EPA's Class II one cylinder engine testing, the "touch-guard" was boxed in by closing off it's
slots, closing off one end, and reducing the size of the opening on the opposite end. The exhaust
exit was re-routed to a different location, and an ejector was added over the top of the exhaust.
The amount of additional metal is fairly minimal and relatively thin-gage. The best examples are
the Kohler CV490 on one of the Craftsman tractors and the Kohler SV590 on the Cub Cadet.
Detailed photos of the SV590 installation can be found in EPA's Safety Study.22
For equipment that use engines with catalysts and require heat shield or equipment
design changes, variable costs are estimated for the sheet metal and/or engine structure redesign
at $1.30 per piece of equipment. Since a portion of engines are assigned to EFI, or will likely
not require additional heat shield or equipment modifications due to current equipment design, it
is estimated that 60 percent of equipment will utilize increased sheet metal and/or engine
structure redesign. This yields a sales weighted average of $0.78 per equipment. Fixed costs
for R&D for the added sheet metal design and/or engine restructure are estimated at $30,000 per
equipment model and tooling changes are also estimated at $45,000 per model. These estimates
are based on the estimates for developing and applying heat shields in the catalyst cost estimates
for Class II and can be seen in Table 6.2-22.
Table 6.2-22: Average Equipment Costs Per Equipment Model
Heat Shield
Additional material for
equipment redesign or air
entrainment pathway
R&D
Tooling Changes
Variable Costs
-0- included in catalyst costs
1.30 per equipment
0.78 avg over all for 60% of
equipment
n/a
n/a
Fixed Costs
-0- included in catalyst costs
n/a
30,000
45,000
6.2.3 Compliance and Certification
The certification and compliance costs include engine dynamometer aging as well as
emission testing pre- and post-aging. Certification and compliance costs are included in this
analysis as fixed costs. After preliminary emission testing, engines are aged on the
dynamometer to the regulatory useful life. The aged engines are then emission tested. The
engine's emission levels must be below the proposed standards. If not, then the engine family
cannot be certified unless the excesses are offset with other engine families within a
manufacturers product line and the manufacturer must be involved in the averaging, banking and
trading program. Engine families will need to certify to the new emission standards using the
6-24
-------
Costs of Control
updated test procedure found in Chapter 4.
The Phase 2 certification database was used as the basis for the number of engine
families to be certified to these proposed standards. The 2005 Certification database contains a
number of engine manufacturers that have certified to the Phase 1 emission standards (1997) as
well as a large number of additional engine manufacturers that have certified to the Phase 2
standards (2002).
6.2.3.1 Measurement Protocol 1065 Compliance Costs
New to the small engine industry are the 1065 protocols for gaseous emission
measurement. These protocols are found in 40 CFR Part 1065. Depending on the analyzing
equipment used by the industry, the certification analyzers may have to be upgraded to the
estimated cost of $250,000. It is possible that less costly upgrades on some analyzers will be
available. A CVS system can be assembled for $50,000 given manufacturer ingenuity.
6.2.3.2 Certification Costs
Certification costs include emission testing after a short engine break-in period and aging
on a dynamometer to the full useful life and then repeat emission testing. Costs for
dynamometer aging of each Class and corresponding useful life are found in ICF's report "Small
SI Engine Technologies and Costs."23 The costs per dynamometer aged engines are estimated in
Table 6.2-3. are based on test setup, data analysis, engine aging operation, dyno costs, scheduled
maintenance, prototype engine cost and fuel.
Table 6.2-23: Dynamometer Aging Certification Costs Per Class and Useful Life
CLASS I
125
250
500
$9,532
$17,462
$33,353
CLASS II
250
500
1,000
$18,413
$34,658
$70,069
The costs for the emission compliance tests are found in Tables 6.2-24 and 6.2-25 and
they are the same for each engine regardless of useful life category. A total of two emission
tests after break-in and two at end of useful life are accounted for in this cost analysis. The
emission test costs are estimated at $2,012 each and are based on the costs for a private test
laboratory in 2005.24
Table 6.2-24: Emission Testing Costs Per Class
CLASS I
all useful lives
$8,048
CLASS II
all useful lives
$8,048
6-25
-------
Draft Regulatory Impact Analysis
Table 6.2-25: Per Engine Family Emission Testing and Dynamometer
Aging Costs Per Class and Useful Life
CLASS I
125
250
500
$17,580
$25,510
$41,401
CLASS II
250
500
1,000
$26,461
$42,706
$78,117
6.2.4 LPG/CNG Engine Costs
Engine manufacturers and equipment manufacturers certify engines to run on LPG. The
number of engine families are obtained from EPA's 2005 Certification Database. Certification
costs found in Section 6.2.3.2 apply to these engines. Part 1065 compliance costs are not applied
since the engine manufacturers are the same as listed in the gasoline section (costs already
applied) and it is estimated that equipment manufacturers contract with a test lab due to the high
cost of maintaining an individual test lab.
For engine certification, all engine families will be required to be tested for baseline
emissions, see Table 6.2-26. Small volume engine manufacturers with a production of 10,000
engines or less can utilize an assigned deterioration factor and do not have to undergo
dynamometer aging or end of life emission testing. Those listed under dynamometer aging in
Table 6.2-26 will need to age the engines and perform end of life emission testing. Several
families were also removed from 250 useful life Class II for they sufficiently met the proposed
Class II standard. Table 6.2-26 lists 3 engine families in Class I and 37 engine families in Class
II for certification.
Table 6.2-26: Number of Engine Families Per Class and
Useful Life Designation for Fixed Cost Analysis
CLASS I
UL
125
250
500
BaselineE
mission
Testing
1
2
~
Dynamo-meter
Aging + End of
Life Emission
Testing
1
2
~
Catalyst
Dev
1
1
~
CLASS II
UL
250
500
1000
Baseline
Emission
Testing
11
19
7
Dynamo-meter
Aging + End of
Life Emission
Testing
11
6**
7
Catalyst
Dev
7*
^7***
7
* Two engine families were sufficiently below the Phase 3 standard
** For Phase 3, companies with small volume production (<10,000) can use an assigned df.
***Eight engine families had catalysts however only one sufficiently met the Phase 3 standard and
therefore the remaining seven engine families will need new catalyst designs to reduce HC+NOx.
6-26
-------
Costs of Control
Table 6.2-27 lists the certification costs as incurred.
Table 6.2-27: Certification Costs As Incurred - LPG
Year
Baseline Emission Testing
Dynamometer Aging
End of Life Emission Test
Total
Class I
2012
$12,072
$26,994
$8.048
$47,114
Class II
2011
$148,888
$900,974
$96.576
$1,146,438
As mentioned above, the technology to reduce emissions to the Phase 3 levels is
catalysts. Catalysts are currently being utilized on LPG engines as shown in EPA's 2005
Certification Database. Basic engine improvement design changes, accounted for in the gasoline
engine families, were not accounted for in these engines for they were already made in the base
engine before they were converted to run on LPG/CNG. Costs that will be applied to these
engines are R&D for catalyst formulation and variable parts costs which will need to be
formulated for the exhaust makeup from these engines. The majority of these engines are two
cylinder engines, however the concerns of the application of catalysts to these engine designs are
relieved in that eight of the V-twin LPG engines are already certified with catalysts. Costs for
catalyst system redesign for seven of the eight engine families are included in order for these
families to meet the Phase 3 standards. Table 6.2-28 lists the R&D and Tooling costs for
catalysts for LPG. Table 6.2-29 contains the totals for fixed cost for each class given the total
number of engine families listed in Table 6.2-26 (3 in Class I and 37 in Class II).
Table 6.2-28: Fixed Costs for Class II OHV Single Cylinder Engine - LPG
Engine Class
Useful life (his)
Valving
II
125, 250, 500
OHV
R&D
Design
Development (5 months)
TOTAL R&D per Engine Line
$20,612
$143,521
$164,133
TOOLING COSTS
TOTAL TOOLING per Engine Line
TOTAL FIXED COSTS
0*
$164,133
*LPG engines are modified from gasoline version engines. Tooling costs are not included for it
is estimated that catalyst volume for these engines will be determined based on a percentage of
engine displacement, as the gasoline version, and therefore the catalysts will fit into the same
muffler space.
6-27
-------
Draft Regulatory Impact Analysis
Table 6.2-29: Total Fixed Costs for LPG
Engine Families, as Incurred, 2005$
Catalyst R&D
Certification Cost
TOTAL
Class I
2012
$492,399
$47,114
$539,413
Class II
2011
$6,072,921
$1,146,438
$7,219,359
Certification data on gaseous fueled engines show that the HC:NOx ratio is higher in
NOx than in HC which is opposite from gasoline engines. Platinum will be used in the precious
metal mixture in order for the oxygen reduced from the NOx to be utilized to convert CO due to
the lack of HC. For Class I engines, the cost estimate presented in Table 6.2-7 is applicable
because it is calculated with a platinum/palladium/rhodium ratio of 5/0/1. For Class II engines,
the 500 and 1000 hour catalyst cost estimates will be modified in order to include more platinum
and all useful life periods will have resized catalysts based on the sales weighted engine
displacement in the certification listing of LPG engines. Table 6.2-30 lists the variable catalyst
costs for Class II OHV Engines, 250 and 500 hour useful life engines (no 1000 hour UL engines
are listed in the LPG certification). Two to three cylinder engines have higher displacement and
therefore costs are recalculated for those engine designs.
6-28
-------
Costs of Control
Table 6.2-30: Variable Catalyst Costs for Class II OHV Engines - LPG
HC+NOx Emission Reduction to Phase 3 Standards
Useful Life
Engine Power (hp)
Engine Displacement (cc)
Engine/Catalyst
Catalyst Volume (cc)*** (per
cylinder)
Substrate Diameter
Substrate* (per cylinder)
Washcoat and Precious Metal
Labor
Labor Overhead 40%
Supplier Markup 29%
Manufacture Price (per catalyst)
Total Catalyst Cost
Heat Shield (2 for v-twin)
Spark Arrester (2 for v-twin)
Hardware Cost to Manufacturer
w/Markup 29% OEM
Add'l Muffler for V-twin
Total Catalyst Cost for LPG
engines
Total Catalyst Cost for Gasoline
Engines
Cost Difference
1 cylinder
250
13.8
415
33%
137
5.25
5.55
4.24
$1.40
$0.56
$3.41
$15.16
$15.16
$4.23
$0.10
$19.49
$25.14
-
$24.14
$23.50
$1.64
500
17.8
389
40%
156
6.00
8.91
4.82
$1.40
$0.56
$4.55
$20.24
$20.24
$4.26
$0.05
$24.55
$31.67
-
$31.67
$20.97
$10.70
1000**
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
2 cylinders
250
18.2
597
33%
197
5.00
3.70
2.96
$1.40
$0.56
$2.50
$11.12
$22.24
$5.90
$0.20
$28.34
$8.22
$7.83
$44.40
$48.05
-$3.66
500
19.2
743
40%
297
5.00
5.20
4.46
$1.40
$0.56
$3.37
$14.99
$30.00
$6.92
$0.10
$37.00
$10.73
$8.95
$56.68
$51.80
$4.87
1000
23
751
50%
376
5.50
6.34
8.86
$1.40
$0.56
$4.97
$22.14
$44.24
$7.32
$0.10
$51.69
$14.99
$8.73
$75.41
$60.06
$15.37
* 50/50- split of metallic vs ceramic substrates
** No one cylinder LPG engines are certified to the 1000 hour useful life
*** these catalyst volumes were calculated from the engine disp in EPA's certification data for 2005
6-29
-------
Draft Regulatory Impact Analysis
Calculations for the rulemaking have been completed using gasoline assumptions. To
account for the increase in costs due to some of the gasoline engines being used as LPG engines,
an increase in the total cost is added to the current gasoline engine variable cost total.
Table 6.2.-31 is an example of costs for 2012 in 2005$.
Table 6.2-31: Change in Variable Cost in 2012, 2005$
Total Engine
Sales
Estimate per
Useful Life
2012
%of
LPG/CNG
Engines in
Useful Life
per Class
#ofCyl
Number
of
Engines
with
change in
Cost
Estimate
Variable
Cost
Change in
2012
Total Change in
costs in 2012
2005$
Class I
125 OHV
250
500
2,953,419
905,005
623,431
0%
1.34%
0.95%
1
1
1
200
4,500
5,398
0*
0
0
0
0
0
Class II
250
500
1000
3,334,488
724,231
821,463
0.67%
12.07%
1.92%
1
2
1
2
2
14,500
10,469
12,918
90,630
18,700
$1.64
-$3.65
$10.70
$4.90
$15.37
2012 Total Increase
$23,780
-$38,306
$138,172
$ 441,661
$ 287,377
$852,673
* Using same cost as Class I gasoline engine.
Table 6.2-31 contains the catalyst cost estimates for LPG engines including a learning
curve discount. This cost estimate is used in year six of the cost estimates.
6-30
-------
Costs of Control
Table 6.2-32: Variable Catalyst Costs with Learning Curve for Class II OHV Engines
LPG; HC+NOx Emission Reduction to Phase 3 Standards
Useful Life
Engine Power (hp)
Engine Displacement (cc)
Engine/Catalyst
Catalyst Volume (cc)*** (per
cylinder)
Substrate Diameter
Substrate* (per cylinder)
Washcoat and Precious Metal
Labor
Labor Overhead 40%
Supplier Markup 29%
Manufacture Price (per catalyst)
Total Catalyst Cost
Heat Shield (2 for v-twin)
Spark Arrester (2 for v-twin)
Hardware Cost to Manufacturer
w/Markup 29% OEM
Add'l Muffler for V-twin
Total Catalyst Cost for LPG
engines
Total Catalyst Cost for Gasoline
Engines
Cost Difference
1 cylinder
250
13.8
415
33%
137
5.25
4.44
4.24
$1.40
$0.56
$3.09
$13.73
$15.90
$3.38
$0.10
$17.21
$22.20
-
$22.20
$20.82
$1.38
500
17.8
389
40%
156
6.00
7.13
4.82
$1.40
$0.56
$4.03
$17.94
$24.88
$3.41
$0.05
$21.40
$27.61
-
$27.61
$18.35
$9.25
1000**
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
2 cylinders
250
18.2
597
33%
197
5.00
2.96
2.96
$1.40
$0.56
$2.29
$10.17
$20.33
$4.72
$0.20
$25.25
$7.32
$6.26
$38.84
$41.79
-$2.95
500
19.2
743
40%
297
5.00
4.16
4.46
$1.40
$0.56
$3.07
$13.65
$27.30
$5.54
$0.10
$32.93
$9.55
$7.16
$49.64
$44.47
$5.17
1000
23
751
50%
376
5.50
5.07
8.86
$1.40
$0.56
$4.61
$20.50
$41.00
$5.86
$0.10
$46.96
$13.62
$6.98
$67.56
$51.97
$15.59
* 50/50- split of metallic vs ceramic substrates
** No one cylinder LPG engines are certified to the 1000 hour useful life
*** these catalyst volumes were calculated from the engine disp in EPA's certification data for 2005
6-31
-------
Draft Regulatory Impact Analysis
6.2.5 Small SI Aggregate Costs
Costs presented in the previous sections are combined here to present streams of costs.
The first, Section 6.2.5.1, presents variable costs (recurring costs) for meeting the Phase 3
exhaust standards. Section 6.2.5.2 presents a stream of fixed costs for meeting the Phase 3
exhaust standards. Costs are based on assuming all engines are gasoline engines. Additional
costs for LPG engines are included at the end of this section.
6.2.5.1 Variable Costs for Meeting Exhaust Standards
Variable costs for Class I are summarized in Table 6.2-10 for engine improvements and
catalysts in near term and long term (with learning) costs. Every engine in Class I is estimated to
have both technologies applied and therefore the costs are added according to useful life period
and then multiplied by the number of engines sold per useful life category, as will be discussed
later. The resultant variable costs per engine is presented in Table 6.2-33. Long term costs are
6 years after the near term costs and include a 20 percent learning curve reduction for engine
improvement components, catalyst substrate and heat shield costs.
Variable costs for Class II are a combination of engine improvements and catalyst or
engine improvements and electronic fuel injection (EFI), see Section 6.2.2. Information on
engine designs and related certification emission results in the 2005 EPA Certification Database
were utilized to determine the percentage of technologies per useful life. A portion of the
engines, one large multi-cylinder engine family per engine manufacturer, are assigned the use of
electronic fuel injection and the remainder catalysts. Some engines would not to require any
costs. Long term costs (learning) are 6 years after the near term costs and include a 20 percent
learning curve reduction for engine improvement components, catalyst substrate and heat shield
costs.
Table 6.2-32: Percentage Technologies Per Useful Life per Class II
Useful Life
250
500
1000
No changes
0.40%
1.90%
8.10%
2FI - Class II
V-twin
13.50%
7.80%
44.50%
V-twin
catalyst
4.50%
0.20%
30.70%
Catalvst-Sinale
Cylinder
81.70%
90.10%
16.70%
6-32
-------
Costs of Control
Table 6.2-33: Variable Costs Per Engine for Meeting
Proposed Exhaust Standards, Per Engine (2005$)
Useful Life (his)
125- SV
125 - OHV
250
500
1000
Class I
Near Term (20 12)
10.56
8.67
12.24
16.05
~
Long Term
(2017)*
9.72
8.04
11.39
14.92
~
Class II
Near Term (20 11)
~
~
32.21
25.32
57.94
Long Term
(2016)*
~
~
27.05
21.38
46.18
*Long term includes learning reduction
The total Small SI engine costs for the first 30 years (2008-2037) were estimated using
sales and growth estimates from the US EPA's NONROAD model. The percentage sales per
useful life category (Class I: 125, 250, 500, Class II: 250, 500, 1000) were calculated from the
manufacturer prescribed useful life period and yearly estimated sales per engine family in the
EPA 2005 Phase 2 certification database (confidential information). The percentages in
Table 6.2-34 were applied to US EPA's NONROAD model sales estimates and the results are
presented in Table 6.2-35 Note that snowblowers are not included for they only have to comply
with the evaporative standards since they are exempted from the exhaust emission standards.
Table 6.2-34: Small SI Engines
Sale Percentages per Useful Life
Useful Life
125- SV
125 - OHV
250
500
1000
Class I
55%
30%
9%
6%
—
Class II
—
—
68%
15%
17%
6-3
-------
Draft Regulatory Impact Analysis
Table 6.2-35: Class I and Class II Projected Sales
per Useful Life Category (snowblowers excluded)
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
9037
CLASS I
125
SV
5,127,510
5,219,801
5,311,789
5,407,460
5,498,863
5,594,305
5,687,801
5,780,726
5,872,307
5,966,857
6,060,404
6,155,080
6,249,153
6,342,877
6,435,905
6,529,799
6,623,557
6,717,690
6,812,592
6,907,322
7,001,813
7,096,586
7,191,371
7,286,256
7,381,095
7,475,836
7,570,510
7,665,267
7,760,044
7 854 864
125
OHV
2,753,967
2,803,536
2,852,943
2,904,327
2,953,419
3,004,681
3,054,897
3,104,807
3,153,994
3,204,777
3,255,021
3,305,871
3,356,397
3,406,736
3,456,701
3,507,131
3,557,488
3,608,047
3,659,018
3,709,897
3,760,648
3,811,550
3,862,459
3,913,421
3,964,359
4,015,244
4,066,093
4,116,987
4,167,891
47.18818
250
OHV
843,888
859,077
874,217
889,962
905,005
920,714
936,101
951,395
966,467
982,028
997,424
1,013,006
1,028,489
1,043,914
1,059,224
1,074,677
1,090,108
1,105,601
1,121,220
1,136,810
1,152,362
1,167,960
1,183,559
1,199,176
1,214,784
1,230,377
1,245,958
1,261,553
1,277,152
1 7.97. 757
500
OHV
581,329
591,793
602,222
613,068
623,431
634,252
644,852
655,387
665,770
676,490
687,096
697,830
708,495
719,121
729,668
740,313
750,943
761,615
772,375
783,115
793,828
804,572
815,319
826,076
836,829
847,570
858,303
869,046
879,792
890 547
CLASS II
250
OHV
3,107,434
3,163,391
3,219,633
3,278,156
3,334,488
3,393,240
3,450,280
3,506,937
3,563,590
3,621,088
3,678,416
3,736,330
3,793,793
3,851,245
3,908,253
3,965,663
4,023,108
4,080,946
4,138,843
4,196,572
4,254,228
4,312,046
4,369,880
4,427,794
4,485,625
4,543,399
4,601,154
4,658,962
4,716,772
4 774 603
500
OHV
674,916
687,070
699,285
711,996
724,231
736,992
749,380
761,686
773,991
786,479
798,930
811,509
823,989
836,468
848,850
861,319
873,795
886,357
898,932
911,471
923,993
936,551
949,112
961,691
974,251
986,799
999,343
1,011,899
1,024,455
1 037016
1000
OHV
765,527
779,312
793,168
807,585
821,463
835,937
849,989
863,946
877,903
892,068
906,191
920,458
934,614
948,768
962,812
976,955
991,107
1,005,355
1,019,618
1,033,840
15048,044
1,062,288
1,076,535
1,090,802
1,105,049
1,119,282
1,133,510
1,147,751
1,161,993
1.176.240
The Total Variable Costs were calculated using the sales information found in
Table 6.2-35 and applying the corresponding variable cost from Table 6.2-33. Results are
presented in Table 6.2-36. Engines used in snowblowers and handheld equipment will require
only evaporative control measures and these are presented in Section 6.5.
6-34
-------
Costs of Control
Table 6.2-36: Variable Costs for Meeting Phase 3 Exhaust Emission Standards, 2005$
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
Class I
125
-
-
-
-
83,668,785
85,121,010
86,543,605
87,957,519
89,350,983
83,764,367
85,077,605
86,406,692
87,727,306
89,043,033
90,348,981
91,667,093
92,983,300
94,304,760
95,637,018
96,966,870
98,293,351
99,623,807
100,954,421
102,286,451
103,617,823
104,947,825
106,276,880
107,607,109
108,937,613
110,268,714
250
-
-
-
-
11,079,868
11,272,180
11,460,567
11,647,805
11,832,335
11,189,968
11,365,401
11,542,952
11,719,371
11,895,137
12,069,597
12,245,682
12,421,512
12,598,044
12,776,019
12,953,672
13,130,875
13,308,609
13,486,363
13,664,307
13,842,164
14,019,837
14,197,383
14,375,087
14,552,827
14,730,647
500
-
-
-
-
10,008,033
10,181,740
10,351,904
10,521,029
10,687,708
10,092,486
10,250,714
10,410,851
10,569,967
10,728,495
10,885,844
11,044,659
11,203,244
11,362,463
11,522,982
11,683,211
11,843,035
12,003,337
12,163,658
12,324,150
12,484,562
12,644,810
12,804,943
12,965,218
13,125,526
13,285,906
Class II: Engine & Equipment
250
_
_
-
105,600,269
107,414,910
109,307,519
111,144,960
112,970,045
96,391,317
97,946,590
99,497,254
101,063,746
102,618,074
104,172,095
105,714,100
107,266,966
108,820,807
110,385,260
111,951,301
113,512,803
115,072,341
116,636,271
118,200,597
119,767,112
121,331,392
122,894,111
124,456,311
126,019,956
127,583,669
129,147,933
500
_
_
-
18,028,276
18,338,075
18,661,185
18,974,876
19,286,458
16,547,001
16,813,987
17,080,182
17,349,093
17,615,917
17,882,688
18,147,395
18,413,968
18,680,708
18,949,270
19,218,104
19,486,159
19,753,877
20,022,348
20,290,888
20,559,804
20,828,336
21,096,600
21,364,775
21,633,197
21,901,632
22,170,161
1,000
_
_
-
46,793,243
47,597,340
48,435,987
49,250,188
50,058,913
40,539,821
41,193,931
41,846,102
42,504,930
43,158,642
43,812,225
44,460,754
45,113,852
45,767,359
46,425,330
47,083,968
47,740,698
48,396,601
49,054,352
49,712,269
50,371,106
51,029,004
51,686,246
52,343,268
53,000,899
53,658,558
54.316.449
6.2.5.2 Fixed Costs
The stream of fixed costs for meeting the proposed exhaust emission standards are
presented per useful life category per Class in Table 6.2-37. The total cost per engine family is
determined by multiplying the costs for engine design changes (R&D, Tooling), certification,
equipment modifications, by the number of engine families in each class per related useful life
which is presented in Table 6.2-38.
EPA does not know the test cell makeup within the facilities of each manufacturer and
therefore estimates that at least two upgraded analyzers will be purchased for a total of $600,000
per engine manufacturer. The certification database lists 16 different engine manufacturers of
nonhandheld engines and 15 engine manufacturers of handheld engines. The 2005 certification
6-35
-------
Draft Regulatory Impact Analysis
database for nonhandheld and handheld engines also lists a number of new offshore
manufacturers. These companies typically certify through independent test laboratories within
the United States and therefore only encounter costs for these upgrades through increased service
fees. This analysis estimates the cost for two manufacturer upgrades. A total of 17 different
nonhandheld engine manufacturers test facilities at 600,000 per test facility yields a total
estimated cost of $10,200,000. This cost is spread evenly across all products for a total of
1,700,000 for each category. These costs are fixed costs in this rulemaking. It is estimated that
engine manufacturers will incur this cost two years prior to implementation of the standard for
each class - 2010 for Class I and 2009 for Class II. Handheld engines must also be certified
using the latest test procedures for small engines. The costs for upgrade of equipment totals
$9,600,000 and is estimated to be incorporated into new certification for the 2010 model year.
Recovered over 5 years yields $2,680,612 per year.
Table 6.2-37: Fixed Costs for Compliance
with 1065, 2005$ (thousands), As Incurred
2008
2009
2010
7011
CLASS I
125
1,700
250
1,700
500
1,700
CLASS II
250
1,700
500
1,700
1000
1,700
HANDHELD
9,600
The number of engine families per Class and per useful life category were taken from
EPA's 2005 Certification Database. For Class I, the 2005 database lists 48 engine families from
traditional companies and 38 newer engine families, accounting for 10 percent of engine sales,
from companies which have been new to the marketplace since the time of the Phase 2
rulemaking promulgation. Engine families still certified to Phase 1 (either through credits,
small engine family flexibilities or averaging) were not included. For Class II, there are a
number of small volume engine families which have not yet been certified to Phase 2 due to
flexibilities in that rulemaking. Due to the low volume sales, these engine families were
estimated to be certified to the 250 hour useful life. For Class I-A, engine families are being
moved to the <80cc category where they already meet the handheld emission standard. Class I-
B engines are traditionally low volume sales engine families; we believe that they will likely be
incorporated into the engine manufacturers ABT programs and certification of these low volume
sales engine families will be covered without engine improvement. Costs for certifiers of LPG
engines are covered in Section 6.2.4. The estimates in Table 6.2-38 represent the number of
engine families per useful life designation used in this cost analysis to calculate fixed costs.
6-36
-------
Costs of Control
Table 6.2-38: Number of Engine Families Per Class
and Useful Life Designation for Certification
CLASS I
125
250
500
39
17
18
CLASS II
250
500
1000
58
20
58
Certification costs include 1065 compliance and engine aging and emission testing for
engine family certification compliance. The costs for 1065 compliance are determined as shown
in Table 6.2-37. This analysis estimates test cells are upgraded two years prior to standard
implementation. The total engine certification costs are calculated by taking the number of
engine families from Table 6.2-38 and multiply them by the emission test and dynamometer
aging costs from Table 6.2-23. This analysis estimates that engine certification costs are
incurred one year prior to standard implementation as shown in Table 6.2-39. Total certification
costs as recovered are presented in Table 6.2-40.
Table 6.2-39: Engine Certification Costs As Incurred, (thousands)
2008
2009
2010
2011
2012
CLASS I
125
$1,700
$686
250
$1,700
$434
500
$1,700
$745
CLASS II
250
$1,700
$1,535
500
$1,700
$854
1000
$1,700
$4,531
Handheld
9,600
Table 6.2-40: Stream of Costs for
Engine Certification by Year As Recovered, (thousands)
2010
2011
2012
2013
2014
2015
2016
125
654
654
654
654
654
CLASS I
250
588
588
588
588
588
500
669
669
669
669
669
250
875
875
875
875
875
CLASS II
500
698
698
698
698
698
1000
,657
,657
,657
,657
,657
Handheld
2,681
2,681
2,681
2,681
2,681
Fixed costs to meet exhaust emission standards are presented throughout sections 6.2.1
Class I and 6.2.2. Class II. The fixed costs include engine improvements, catalyst development,
and EFI development and application. All Class I engine families are assigned engine
6-37
-------
Draft Regulatory Impact Analysis
improvements and catalyst development costs. The number of engine families are taken from
the 2005 EPA Certification Database. Table 6.2-41 presents the number of engine families
estimated per technology package. Information on the number of cylinders per engine family
and the number of manufacturers per Class was obtained from EPA's 2005 Certification
Database.
Table 6.2-41: Estimates of the Number of Engine Families per Technology Package
Technology/Useful Life
- One Cylinder Engine Improvements With Catalyst
- Two or More Cylinders per Engine for Catalyst
- Electronic Fuel Injection on Two or More Cylinder Engines
Total Number of Engine Families
250
45
11
2
58
500
13
4
3
20
1000
28
24
6
58
Table 6.2-42: Total Fixed Costs as Incurred (thousands)
for Engines to Meet Phase 3 Exhaust Emission Standards
l&D
TOOLING
TOTAT
CLASS 1
125
SV
1,888
3,630
5 518
125
OHV
12,838
12,342
75 180
250
OHV
6,419
6,171
1? 5QO
500
OHV
6,796
6,534
13 330
CLASS 11
250
OHV
21,301
21,258
4? 559
500
OHV
6,653
6,566
13 719
1000
OHV
20,102
20,946
41 048
Table 6.2-43: Total Fixed Costs as Recovered (thousands)
for Engines to Meet Phase 3 Exhaust Emission Standards
2011
2012
2013
2014
2015
2016
CLASS 1
125
SV
~
,475
,475
,475
,475
.475
125
OHV
~
6,811
6,811
6,811
6,811
6.811
250
OHV
~
3,405
3,405
3,405
3,405
3.405
500
OHV
~
3,606
3,606
3,606
3,606
3.606
CLASS 11
250
OHV
11,504
11,504
11,504
11,504
11,504
~
500
OHV
3,574
3,574
3,574
3,574
3,574
~
1000
OHV
11,088
11,088
11,088
11,088
11,088
-
6-38
-------
Costs of Control
Total fixed costs for Small SI exhaust emissions are shown in Table 6.2-44.
Table 6.2-44: Certification and Technology Fixed Costs
for Engines to Meet Proposed Exhaust Standards, As Recovered
2010
2011
2012
2013
2014
2015
2016
TOTAL
Class 1
175
8,940
8,940
8,940
8,940
8,940
44fiqq
750
3,993
3,993
3,993
3,993
3,993
19 967
500
4,275
4,275
4,275
4,275
4,275
71 ^
Class 11
750
12,380
12,380
12,380
12,380
12,380
61 898
500
4,272
4,272
4,272
4,272
4,272
71 ^X
1000
12,745
12,745
12,745
12,745
12,745
63 775
Handheld
2,681
2,681
2,681
2,681
2,681
10777
Equipment companies using Class II engines are also estimated to incur fixed costs in
redesigning equipment models to incorporate Phase 3 Class II engines. The PSR database shows
there are 413 businesses using Class II engines.25 Assuming each business on average produces
three unique models requiring clearly different redesign yields a number of 1239 redesigns.
Table 6.2-22 contains equipment costs per equipment model and Table 6.2-45 contains the total
equipment costs as incurred and recovered.
Ts
ible 6.2-45: Total Class II Equipment Cost
llncurred
2010
2011
2012
2013
2014
2015
TOTAL
92,925,000
As Recovered
25,987,098
25,987,098
25,987,098
25,987,098
25,987,098
129.935.492
6.2.5.3 Operating Cost Savings
The application of electronic fuel injection to an estimated additional 17.7 percent of the
Class II engines is expected to result in fuel savings. Fuel savings from the use of fuel injection
on Class II engines is estimated at 10 percent. Kohler has been offering a fuel injected Class II
engine for nearly 10 years and two articles (1996 OEM Off-Highway and 1998 Diesel
Progress)26'27 claim 15-20 percent fuel savings over carbureted engines. We elected to
conservatively use a figure often percent. In calculating the fuel savings, we use a gasoline price
of $1.81 per gallon without taxes.28 Table 6.2-46 presents estimated fuel savings for Class II
engines with electronic fuel injection. The improvements and catalyst application to Class I
engines are estimated to result in no operating or fuel savings. Fuel savings that are obtained
from evaporative reduction technologies are presented later in the evaporative portion of this
6-39
-------
Draft Regulatory Impact Analysis
proposal. In calculating the fuel savings, we use a gasoline price of $1.81 per gallon without
taxes.
29
Table 6.2-46: Fuel Savings from the Increased
Use of Electronic Fuel Injection on Class II Engines
Year
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
Gallons
0
0
10,173,297
18,376,598
26,158,818
31,081,817
35,936,184
39,616,047
42,132,893
44,068,991
45,654,106
47,024,456
48,137,286
49,132,949
50,046,687
50,928,776
51,781,644
52,622,410
53,452,741
54,275,859
55,091,652
55,900,128
56,703,268
57,503,764
58,301,990
59,098,563
59,893,659
60,685,412
61.473.943
Fuel Savings $
0
0
$18,454,361
$33,335,150
$47,452,096
$56,382,417
$65,188,238
$71,863,509
$76,429,068
$79,941,150
$82,816,549
$85,302,363
$87,321,037
$89,127,169
$90,784,690
$92,384,800
$93,931,901
$95,457,051
$96,963,273
$98,456,408
$99,936,257
$101,402,832
$102,859,728
$104,311,828
$105,759,810
$107,204,794
$108,647,097
$110,083,337
$111.513.733
6-40
-------
Costs of Control
6.2.5.4 Total Aggregate Costs
The aggregate costs for meeting the exhaust emission standards are presented in
Table 6.2-47. Aggregate costs include variable costs and fixed costs for engine manufacturers
(technology, certification, 1065 compliance), equipment manufacturers and LPG engine families
and converters. An average cost per engine is presented in Table 6.2-48 and the aggregate costs
with fuel savings is presented in Table 6.2-49.
Table 6.2-47:
for Exhaust Emission
Total Aggregate for 30 year Cost Analysis
Standard Compliance without Fuel Savings, 2005$
Year
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
9037
Exhaust Only
Class I
0
0
122,084,986
123,903,229
125,684,375
120,443,340
122,188,014
105,046,821
106,693,720
108,360,496
110,016,644
111,666,665
113,304,422
114,957,434
116,608,057
118,265,267
119,936,019
121,603,753
123,267,260
124,935,752
126,604,442
128,274,908
129,944,548
131,612,472
133,279,206
134,947,414
136,615,966
n8 98S 967
Class II
0
231,735,198
234,740,187
237,874,288
240,917,033
243,939,317
158,329,126
160,883,764
163,430,833
166,003,899
168,556,986
171,109,568
173,642,413
176,193,100
178,745,385
181,315,103
183,887,430
186,452,300
189,013,944
191,582,803
194,152,312
196,725,417
199,294,850
201,861,721
204,427,738
206,996,128
209,564,630
919 ndrn7
1065 Compliance
Handheld
2,680,612
2,680,612
2,680,612
2,680,612
2,680,612
6-41
-------
Draft Regulatory Impact Analysis
Table 6.2-48: Sales Weighted Average Per-Equipment
Cost Estimates (Without Fuel Savings), 2005$
Short Term Costs
^years 1-5) per Class per
Useful Life
Variable
Fixed
Total
Long Term
Class 1
125
9.90
1.10
11.00
9.13
250
12.24
4.41
16.66
11.39
500
16.05
6.86
22.91
14.92
Class 11
250
32.99
6.42
39.41
27.84
500
26.10
18.17
44.27
22.16
1000
58.72
26.51
85.23
47.22
Handheld
~
0.30
0.30
0.00
Long term is without fixed costs and with learning, if applicable
Table 6.2-49: Total Aggregate for 30 year Cost Analysis
for Exhaust Emission Standard Compliance with Fuel Savings, 2005$
Year
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
Exhaust Only
Class I
$0
$0
$0
$0
$0
$134,647,294
$136,508,481
$112,806,498
$114,575,051
$116,364,950
$118,143,436
$119,915,342
$121,674,078
$123,449,196
$125,221,748
$127,001,374
$128,795,542
$130,586,470
$132,372,859
$134,164,600
$135,956,554
$137,750,415
$139,543,389
$141,334,520
$143,124,374
$144,915,811
$146,707,616
$148.500.226
Class II
0
$213,280,837
$201,405,037
$190,422,192
$184,534,617
$178,751,079
$86,465,617
$84,454,696
$83,489,683
$83,187,350
$83,254,623
$83,788,531
$84,515,244
$85,408,410
$86,360,585
$87,383,202
$88,430,379
$89,489,027
$90,557,536
$91,646,546
$92,749,480
$93,865,690
$94,983,022
$96,101,911
$97,222,944
$98,349,031
$99,481,294
$100.620.305
1065 Compliance
Handheld
2,680,612
2,680,612
2,680,612
2,680,612
2,680,612
6-42
-------
Costs of Control
At a 7 percent discount rate, over 30 years, the estimated annualized cost to
manufacturers for Small SI exhaust emission control, without fuel savings, is $265 million. The
corresponding estimated annualized fuel savings due to the use of electronic fuel injection on
Class II engines is $63 million. At a 3 percent discount rate, the estimated annualized cost to
manufacturers for Small SI exhaust emission control, without fuel savings, is $273 million. The
corresponding estimated annualized fuel savings due to the use of electronic fuel injection on
Class II engines is $71 million.
6.3 Exhaust Emission Control Costs for Outboard and Personal Watercraft
Marine Engines
This section presents our cost estimates for meeting the proposed exhaust emission
standards for outboard and personal watercraft marine engines.
Less than a decade ago, outboard and personal watercraft (OB/PWC) engines were
primarily two-stroke carbureted engines. There were no emission control requirements. Since
then, manufacturers have used two primary strategies to meet exhaust emission standards. The
first is two-stroke direct injection. By injecting the fuel directly into the combustion chamber
after the exhaust port closes, the short-circuiting fuel losses with traditional two-strokes can be
largely eliminated. The second approach is to convert to using four-stroke engines, either
carbureted or fuel-injected. One other approach that has been used by one PWC manufacturer
has been the use of a two-way catalyst in the exhaust of a two-stroke engine. Today, engine
sales are a mix of old and new technology. We anticipate that the proposed standards will
largely be met by phasing out the old-technology engines and using technology already available
in the marketplace.
Since California ARB has adopted standards similar to those we are proposing,
manufacturers have already started with design and testing efforts to meet our proposed
standards. To reflect this in the cost analysis, we include no estimated costs for R&D to
introduce the various emission-control technologies. This reflects the expectation that
manufacturers will not need to conduct additional R&D for EPA's requirements, since they are
introducing those technologies for sale in California. As noted below, we are including
estimated R&D expenditures as part a compliance cost, since EPA's proposed NTE standards
represent an incremental requirement beyond what California ARB has adopted.
For the purpose of this analysis, we divide outboards into five power categories and PWC
into three power categories. We present cost estimates of various emission-control technologies
for each of these power categories. Additional detail on the per-engine costs presented in this
section is available in the docket.30 Table 6.3-1 presents these power categories and the engine
size we use to represent each category.
6-43
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Draft Regulatory Impact Analysis
Table 6.3-1: Engine Sizes Used for Cost Analysis
Outboard Engines
Personal
Watercraft
Engines
Power Range
0-25 hp
25-50 hp
50-100 hp
100-175 hp
>175 hp
50-100 hp
100-175 hp
>175 hp
Engine Power
9.9 hp
40 hp
75 hp
125 hp
225 hp
85 hp
130 hp
175 hp
Displacement
0.25 L
0.76 L
1.60 L
1.80L
3.00 L
1.65 L
1.85L
2.50 L
Cylinders
2
3
3
4
6
2
3
4
6-44
-------
Costs of Control
6.3.1 Two-Stroke Direct Injection
Traditional outboards use carbureted two-stroke engine designs where the fuel and air are
mixed in the carburetor then pumped into the combustion chamber through the crankcase. The
piston itself acts to open and close the intake and exhaust ports. As a result, fuel may be lost out
the exhaust port. Better control of the fuel can be achieved using indirect injection in place of
the carburetor; however, this does not prevent short-circuiting losses. Indirect injection is
primarily used on the largest two-stroke engines. Direct-injection has been used by
manufacturers to reduce emissions from two-stroke outboards. By injecting the fuel directly into
the cylinder after the exhaust port is closed, short-circuiting losses can be minimized.
Table 6.3-2 and 6.3-3 present incremental costs of applying direct injection to outboards and
PWC, respectively. For the largest power category, costs are presented incremental to indirect
injection. For the remaining categories, costs are presented incremental to carbureted engines.
For 135 hp PWC engine, incremental costs are presented for both IDI and carbureted engines
because baseline engines in this power category use both approaches.
Table 6.3-2: Outboard—Projected Incremental Costs for 2-Stroke Direct Injection
Hardware Cost to Manufacturer
carburetor(s)
fuel metering solenoids
IDI injectors
fuel distributer
pressure regulator
air compressor
air regulator
throttle body position sensor
intake manifold
fuel pump
electronic control module
air intake temperature sensor
manifold air pressure sensor
injection timing sensor/timing wheel
wiring/related hardware
Total Incremental Hardware Cost
Engine Manufacturer Markup
labor at $28/hour
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
9.9 hp
carb.
($28)
$36
~
~
~
$80
$15
$30
$5
$3
$85
$5
$10
$5
$20
$266
$13
$5
$82
$13
$380
40 hp
carb.
($114)
$60
~
~
~
$100
$15
$35
$5
$0
$90
$5
$10
$8
$30
$244
$15
$6
$77
$12
$354
75 hp
carb.
($135)
$66
~
~
~
$120
$17
$35
$9
($5)
$95
$5
$11
$9
$30
$257
$19
$8
$82
$13
$379
125 hp
carb.
($165)
$96
~
~
~
$140
$20
$40
$10
($6)
$100
$5
$11
$10
$50
$311
$22
$9
$99
$16
$456
225 hp
IDI
~
$156
($102)
($25)
($35)
$165
$22
$10
($5)
($35)
$0
$0
$0
$0
$0
$151
$14
$6
$49
$8
$228
6-45
-------
Draft Regulatory Impact Analysis
Table 6.3-3: PWC—Projected Incremental Costs for 2-Stroke Direct Injection
Hardware Cost to Manufacturer
carburetor(s)
fuel metering solenoids
IDI injectors
fuel distributer
pressure regulator
air compressor
air regulator
throttle body position sensor
intake manifold
fuel pump
electronic control module
air intake temperature sensor
manifold air pressure sensor
injection timing sensor/timing wheel
wiring/related hardware
Total Incremental Hardware Cost
Engine Manufacturer Markup
labor at $28/hour
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
85 hp
carb.
($114)
$44
~
~
~
$120
$17
$35
$9
($5)
$95
$5
$11
$9
$20
$246
$19
$8
$79
$12
$364
130 hp
carb.
($165)
$72
~
~
~
$140
$20
$40
$10
($6)
$100
$5
$11
$10
$30
$267
$22
$9
$86
$13
$398
130 hp
IDI
~
$72
($51)
($20)
($30)
$140
$20
$0
($10)
($30)
$0
$0
$0
$0
$0
$91
$12
$5
$31
$5
$144
175 hp
IDI
~
$104
($68)
($25)
($35)
$165
$22
$0
($5)
($35)
$0
$0
$0
$0
$0
$123
$12
$5
$41
$6
$186
6-46
-------
Costs of Control
6.3.2 Migration from Two-Stroke to Four-Stroke Engines
The primary technology that manufacturers are using to meet exhaust emissions
standards has been to convert their product offering more to four-stroke engines. Because four-
stroke engines are common in the market today, we do not include costs for research and
development or warranty. Rather, we anticipate that manufacturers will sell more of the four-
stroke engines and phase out the carbureted two-stroke designs as a result of the proposed
standards. Tables 6.3-4 and 6.3-5 below present a comparison between costs for two-stroke and
four-stroke outboard and PWC engines, respectively. These costs are based on prices for current
product offerings.
Table 6.3-4: Outboard—Projected Incremental Costs for 4-Stroke
2-stroke baseline technology
4-stroke control technology
2-stroke cost
4-stroke cost
Markup at 29%
Total Incremental Cost
9.9 hp
carb
carb
$900
$1,124
$65
$289
40 hp
carb
carb
$2,101
$2,633
$154
$686
75 hp
carb
carb
$3,076
$3,861
$228
$1,013
125 hp
carb
EFI
$4,195
$5,504
$380
$1,689
225 hp
DPI
EFI
$6,339
$7,761
$412
$1,834
Table 6.3-5: PWC—Projected Incremental Costs for 4-Stroke
2-stroke baseline technology
4-stroke control technology
2-stroke cost
4-stroke cost
Markup at 29%
Total Incremental Cost
85 hp
carb
EFI
$3,319
$4,350
$299
$1,330
130 hp
DPI
EFI
$4,578
$5,587
$293
$1,302
175 hp
DPI
EFI
$5,862
$7,207
$390
$1,735
6-47
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Draft Regulatory Impact Analysis
6.3.3 Four-Stroke Electronic Fuel Injection
Manufacturers can gain better control of their fuel and air management through the use of
electronic fuel injection. This is often used in larger OB/PWC engines today. For this analysis,
we consider the use of a port fuel-injection system, which refers to individual injectors located at
each intake port in the engine. In addition to the injectors, this system includes a fuel rail,
pressure regulator, electronic control module, manifold air pressure and temperature sensors, a
high pressure fuel pump, a throttle assembly, a throttle position sensor, and a magnetic
crankshaft pickup for engine speed. Tables 6.3-6 and 6.3-7 present the incremental costs of a
port fuel-injection system compared to a carburetor-based fuel system for outboards and personal
watercraft, respectively.
Table 6.3-6: Outboard—Projected Incremental Costs for 4-Stroke EFI
Hardware Costs
carburetor(s)
injectors
fuel rail
pressure regulator
intake manifold
throttle body position sensor
fuel pump
electronic control module
air intake temperature sensor
manifold air pressure sensor
injection timing sensor
wiring/related hardware
Hardware Cost to Manufacturer
Engine Manufacturer Markup
labor at $28/hour
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
9.9 hp
($28)
$34
$40
$15
$5
$30
$13
$95
$5
$10
$5
$20
$244
$3
$1
$72
$12
$332
40 hp
($114)
$51
$55
$15
$5
$35
$10
$100
$5
$10
$8
$30
$210
$4
$2
$63
$11
$289
75 hp
($135)
$51
$65
$20
$6
$35
$10
$105
$5
$11
$9
$30
$212
$4
$2
$63
$11
$291
125 hp
($165)
$68
$70
$30
$10
$40
$14
$110
$5
$11
$10
$40
$243
$4
$2
$72
$12
$333
225 hp
($240)
$102
$80
$35
$15
$50
$17
$115
$5
$11
$10
$60
$260
$4
$2
$77
$13
$356
6-48
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Costs of Control
Table 6.3-7: PWC—Projected Incremental Costs for 4-Stroke EFI
Hardware Costs
carburetor(s)
injectors
fuel rail
pressure regulator
intake manifold
throttle body position sensor
fuel pump
electronic control module
air intake temperature sensor
manifold air pressure sensor
injection timing sensor
wiring/related hardware
Hardware Cost to Manufacturer
Engine Manufacturer Markup
labor at $28/hour
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
85 hp
($135)
$34
$65
$20
$6
$35
$10
$105
$5
$11
$9
$20
$185
$4
$2
$55
$9
$255
130 hp
($165)
$51
$70
$30
$10
$40
$14
$110
$5
$11
$10
$30
$216
$4
$2
$64
$11
$297
175 hp
($240)
$68
$80
$35
$15
$50
$17
$115
$5
$11
$10
$40
$206
$4
$2
$61
$10
$283
6-49
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Draft Regulatory Impact Analysis
6.3.4 Catalysts
We believe the proposed OB/PWC exhaust emission standards can be achieved without
the use of catalysts. At this time, three-way catalysts have not been demonstrated on OB/PWC
engines. However, one manufacturer has been using a two-way catalyst on PWCs with 2-stroke
engines for several years. We include research and development costs for this technology
because it is not currently used in the marine industry, but is an alternative we assess in Chapter
11. Catalyst sizes and formulations are based on the analysis discussed below for SD/I engines.
Tables 6.3-8 and 6.3-9 present the incremental cost of adding catalysts to four-stroke, electronic
fuel-injection OB and PWC engines, respectively.
Table 6.3-8: Outboard—Projected Incremental Costs for Catalytic Control
Catalyst Unit Price
catalyst volume (L)
substrate diameter (cm)
substrate
ceria/alumina
Pt/Pd/Rd
can (18 gauge SS)
Total Material Cost
Labor
labor overhead at 40%
supplier markup at 29%
Manufacturer Price per Unit
Hardware Cost to Manufacturer
catalyst
exhaust manifold modifications
oxygen sensor
Total Incremental Hardware Cost
Engine Manufacturer Markup
labor at $28/hour
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
Fixed Cost to Manufacturer
research & development
tooling
units/year
years to recover
Fixed Cost/Unit
Total Incremental Cost
9.9 hp
0.09
4.5
$2
$1
$2
$0.4
$6
$14
$6
$8
$33
$33
$15
$25
$73
$1
$1
$22
$2
$99
$342,788
$75,000
5,000
5
$23
$122
40 hp
0.27
6.0
$4
$3
$7
$0.8
$15
$14
$6
$10
$45
$45
$17
$25
$87
$1
$1
$26
$2
$116
$352,938
$75,000
5,600
5
$21
$137
75 hp
0.56
8.5
$5
$6
$16
$1
$29
$14
$6
$14
$62
$62
$20
$25
$107
$1
$1
$32
$2
$143
$362,068
$75,000
6,400
5
$19
$162
125 hp
0.63
9.0
$6
$7
$18
$1
$32
$14
$6
$15
$67
$67
$25
$25
$117
$1
$1
$34
$3
$156
$372,980
$75,000
5,900
5
$21
$177
225 hp
1.05
10.0
$8
$12
$29
$2
$52
$14
$6
$21
$92
$92
$30
$25
$147
$1
$1
$43
$3
$195
$388,643
$75,000
4,700
5
$27
$222
6-50
-------
Costs of Control
Table 6.3-9: PWC—Projected Incremental Costs for Catalytic Control
Catalyst Unit Price
catalyst volume (L)
substrate diameter (cm)
substrate
ceria/alumina
Pt/Pd/Rd
can (18 gauge SS)
Total Material Cost
Labor
labor overhead at 40%
supplier markup at 29%
Manufacturer Price per Unit
Hardware Cost to Manufacturer
catalyst
exhaust manifold modifications
oxygen sensor
Total Incremental Hardware Cost
Engine Manufacturer Markup
labor at $28/hour
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
Fixed Cost to Manufacturer
research & development
tooling
units/year
years to recover
Fixed Cost/Unit
Total Incremental Cost
85 hp
0.58
9.0
$5
$7
$16
$1
$30
$14
$6
$14
$63
$63
$35
$25
$123
$1
$1
$36
$3
$165
$363,502
$75,000
1,700
5
$71
$236
130 hp
0.65
9.0
$6
$7
$18
$1
$33
$14
$6
$15
$68
$68
$40
$25
$133
$1
$1
$39
$3
$177
$371,332
$75,000
5,300
5
$23
$200
175 hp
0.88
9.0
$7
$10
$25
$2
$44
$14
$6
$18
$82
$82
$45
$25
$152
$1
$1
$45
$4
$202
$381,016
$75,000
1,000
5
$126
$328
6.3.5 Certification and Compliance
Outboard and PWC engines must already be certified to meet the current EPA HC+NOx
exhaust emission standards. We therefore do not anticipate any increase in clerical work
associated with these proposed standards. In addition, manufacturers are likely to meet the
proposed standards by selling more of their lower-emission engines, which are certified today.
However, manufacturers may need to adjust engine calibrations to meet the proposed standard
and collect further data to demonstrate compliance with the proposed not-to-exceed zone. We
therefore allow on average two months of R&D for each engine family as part of the certification
process. Considering two engineers and three technicians and the corresponding testing costs for
6-51
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Draft Regulatory Impact Analysis
the two-month period, we estimate a total cost of $130,000 per engine family. Unless engine
designs were significantly changed, manufacturers could recertify engine families each year
using carryover of this original test data. This cost is therefore amortized over five years of
engine sales with an average volume of 5,500 engines per family for outboards and 4,200
engines per family for PWC. The resulting cost is $5 per engine for outboards and $6 for PWC.
6.3.6 Operating Cost Savings
We anticipate that the proposed standards will largely be met on average by phasing out
old, high-emitting technologies, such as carbureted two-stroke engines and replacing them with
currently available clean technologies such as four-stroke engines and direct-injection two-stroke
engines. In addition to having lower emissions, these newer-technology engines have
significantly lower fuel consumption. Over the life of an engine, these fuel savings result in
significant operating cost savings. In calculating the fuel savings, we use a gasoline price of
$1.81 per gallon without taxes.31
The largest portion of the fuel savings would come from phasing out carbureted
crankcase-scavenged two-stroke engines. As discussed in Chapter 4, scavenging losses from
these engines can result in more than 25 percent of the fuel passing through the engine unburned.
In addition, we model incremental fuel-consumption benefits between fuel-injected two-stroke
engines, carbureted four-stroke engines, and fuel-injected four strokes. These fuel consumption
rates and their derivation are described in more detail in the docket.32
Table 6.3-10: Projected Fuel Savings for OB/PWC Engines
Annual Per-Engine Gallons Consumed
Average Life (years)
Anticipated Reduction in Fuel Consumption
Lifetime Gallons Saved
Lifetime Cost Savings
Discounted Cost Savings (7%)
Outboard
72
19
5.2%
72
$130
$77
PWC
225
9.9
4.7%
103
$187
$142
6.3.7 Total OB/PWC Engine Costs
As discussed above, we anticipate that manufacturers would meet the proposed standards
largely by changing their technology mix from older to newer technologies. For this reason, our
estimated per-engine costs for the average OB/PWC engine reflect a mix of technology changes.
Table 6.3-11 presents the baseline technology mix by power class. This technology mix is based
on an analysis of sales projections submitted to EPA by OB/PWC manufacturers at time of
certification. These sales projections are confidential, but a general description of this analysis is
6-52
-------
Costs of Control
available in the docket.33
Table 6.3-11: Baseline Technology Mix for OB/PWC Engines
Outboards
9.9 hp
40 hp
75 hp
125 hp
225 hp
PWC
85 hp
130 hp
175 hp
2-Stroke
Carbureted
24%
32%
20%
20%
0%
30%
5%
0%
2-Stroke
Indirect Injection
0%
0%
0%
0%
25%
60%
0%
70%
2-Stroke
Direct Injection
0%
2%
10%
30%
60%
10%
5%
30%
4-Stroke
Carbureted
76%
35%
0%
0%
0%
0%
0%
0%
4-Stroke
Fuel Injection
0%
32%
70%
50%
15%
0%
90%
0%
To develop the control technology mix, we made three adjustments to the baseline
technology mix. First, we considered that all the 2-stroke carbureted and indirect injection
engines would be replaced by either 2-stroke direct injection or 4-stroke engines. Second, we
included calibration costs for the for the 2-stroke direct injection and 4-stroke engines for better
emission performance. These engines are well below the existing HC+NOx standards; however,
there is currently wide variability in certified emission levels. We believe the proposed
standards would require engine manufacturers to pay closer attention to emissions calibrations
for their higher-emitting new technology engines. Third, we included the conversion of a small
number of 2-stroke direct injection engines to 4-stroke based on product plans conveyed to us in
private conversations with manufacturers. While there is no way of knowing exactly what the
actual technology mix will be, we believe our analysis represents a reasonable scenario.
Table 6.3-12 presents the projected technology mix for this control scenario.
6-53
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Draft Regulatory Impact Analysis
Table 6.3-12: Projected Control Technology Mix for OB/PWC Engines
Outboards
9.9 hp
40 hp
75 hp
125 hp
225 hp
PWC
85 hp
130 hp
175 hp
2-Stroke
Carbureted
0%
0%
0%
0%
0%
0%
0%
0%
2-Stroke
Indirect Injection
0%
0%
0%
0%
0%
0%
0%
0%
2-Stroke
Direct Injection
0%
2%
10%
30%
50%
0%
5%
30%
4-Stroke
Carbureted
100%
66%
20%
0%
0%
100%
0%
0%
4-Stroke
Fuel Injection
0%
32%
70%
70%
50%
0%
95%
70%
We developed the per-engine costs based on the technology mix and technology cost
tables presented above. As discussed above, our cost estimates include both variable and fixed,
and we distinguish between near-term and long-term costs. Because our analysis amortizes fixed
costs over 5 years, the long-term costs are made up of variable costs only. Variable costs are
lower in the long term due to the learning effect discussed above. Table 6.3-13 presents these
average per-engine cost estimates.
Table 6.3-13: OB/PWC Per-Engine Cost Estimates (Without Fuel Savings)
OB aggregate
9.9 hp
40 hp
75 hp
125 hp
225 hp
PWC aggregate
85 hp
130 hp
175 hp
Short Term (years 1-5)
Fixed
$11
$5
$5
$8
$15
$27
$19
$29
$14
$45
Variable
$273
$69
$216
$203
$338
$690
$340
$870
$85
$1,290
Total
$284
$74
$222
$210
$353
$717
$359
$899
$98
$1,336
Long Term (years
6-10)
$219
$55
$173
$162
$270
$552
$272
$696
$68
$1,032
6.3.8 OB/PWC Aggregate Costs
Aggregate costs are calculated by multiplying the per-engine cost estimates described
above by projected engine sales. Engine sales are based on estimates supplied by the National
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Costs of Control
Marine Manufacturers Association (www.nmma.org) and projections for future years are based
on the growth rates in the NONROAD model. Fuel-con sumption reductions are calculated using
the NONROAD based on population estimates. These population estimates in the NONROAD
model are similar to those estimated by NMMA. A description of the sales and population data
and our analysis of the data are available in the docket.34 Table 6.3-14 presents the projected
costs of meeting the proposed exhaust emission standards over a 30-year time period, with and
without the fuel savings. Fuel savings from the proposed evaporative emission standards are not
included in this table, but they are presented separately below.
The population and sales data reported by NMMA, suggest that the NONROAD model
may somewhat underestimate the useful life of outboard and personal watercraft marine engines.
If useful life were back-calculated—dividing NMMA population by sales and adjusted for
growth—we would get a longer average life estimate. As a result, the per-engine fuel savings
described above may be understated. Because the current approach gives us a conservative
benefits estimate, and because we do not have new data on average lives for marine engines to
update the estimates in the NONROAD model, we are not proposing to update the model at this
time. For this reason, the 30-year stream may give a better view of the impact of the fuel savings
than the per-engine analysis.
At a 7 percent discount rate, over 30 years, the estimated annualized cost to
manufacturers for OB/PWC exhaust emission control is $108 million. The corresponding
estimated annualized fuel savings due to more efficient engines is $57 million. At a 3 percent
discount rate, the estimated annualized cost to manufacturers for OB/PWC exhaust emission
control is $103 million. The corresponding estimated annualized fuel savings due to more
efficient engines is $64 million.
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Draft Regulatory Impact Analysis
Table 6.3-14: Projected 30-Year Aggregate Cost Stream for OB/PWC Engines
Year
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
Without Fuel Savings
OB
$84,242,873
$84,850,618
$85,473,947
$86,097,276
$86,720,605
$67,170,271
$67,649,631
$68,122,998
$68,596,366
$69,069,734
$69,543,101
$70,016,469
$70,489,837
$70,963,204
$71,436,572
$71,909,940
$72,383,307
$72,859,671
$73,336,035
$73,812,398
$74,288,762
$74,765,126
$75,241,489
$75,717,853
$76,194,217
$76,670,580
$77,146,944
$77,623,308
$78,099,671
$78,576,035
PWC
$28,070,735
$28,273,243
$28,480,943
$28,688,644
$28,896,344
$22,049,479
$22,206,835
$22,362,224
$22,517,613
$22,673,001
$22,828,390
$22,983,779
$23,139,168
$23,294,557
$23,449,946
$23,605,334
$23,760,723
$23,917,096
$24,073,468
$24,229,840
$24,386,213
$24,542,585
$24,698,957
$24,855,329
$25,011,702
$25,168,074
$25,324,446
$25,480,819
$25,637,191
$25,793,563
With Fuel Savings
OB
$80,280,824
$76,945,029
$73,647,593
$70,386,332
$67,153,841
$43,776,465
$40,438,909
$37,127,048
$33,855,111
$30,639,110
$27,488,204
$24,419,419
$21,461,639
$18,701,687
$16,563,074
$14,854,769
$13,335,677
$11,975,643
$10,861,355
$9,875,510
$9,063,546
$8,383,095
$7,792,111
$7,318,336
$6,919,063
$6,603,636
$6,371,857
$6,192,965
$6,049,717
$5,935,965
PWC
$25,794,193
$23,741,117
$21,688,747
$19,661,793
$17,666,970
$8,674,759
$6,733,884
$4,863,926
$3,087,340
$1,449,882
$588,957
$(4,321)
$(464,863)
$(835,954)
$(1,140,064)
$(1,376,955)
$(1,557,763)
$(1,693,743)
$(1,784,708)
$(1,830,521)
$(1,842,333)
$(1,854,144)
$(1,865,948)
$(1,877,773)
$(1,889,590)
$(1,901,401)
$(1,913,212)
$(1,925,031)
$(1,936,841)
$(1,948,650)
6.4 Exhaust Emission Control Costs for Sterndrive/Inboard Marine
Engines
This section presents our cost estimates for meeting the proposed exhaust emission
standards for sterndrive and inboard marine engines.
Sterndrive and inboard (SD/I) marine engines are typically "marinized" using automotive
engine blocks. There are a few exceptions where unique engine blocks are used, but these
applications represent a very small portion of the sales volume. Typical automotive blocks are
3.0 liter in-line 4-cylinder engines, 4.3 liter V-6 engines, and V-8 engines ranging from 5.0 to 8.2
liters total displacement. For purposes of this analysis, we present costs for an in-line 4 cylinder
engine, a V-6 engine, and three V-8 engine configurations. In addition, this analysis considers
costs to the original engine manufacturer and to the engine "marinizer." Additional detail on the
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Costs of Control
projected costs may be found in the docket.35
Because California ARB has adopted standards similar to those we are proposing,
manufacturers have already started with design and testing efforts to meet our proposed
standards. To reflect this in the cost analysis, we include no estimated costs for R&D to
introduce the various emission-control technologies. This reflects the expectation that
manufacturers will not need to conduct additional R&D for EPA's requirements, since they are
introducing those technologies for sale in California. As noted below, we are including
estimated R&D expenditures as part a compliance cost, because EPA's proposed NTE standards
represent an incremental requirement beyond what California ARB has adopted.
6.4.1 Fuel Injection
Current SD/I engines are sold with carburetors or with fuel-injection systems. The
smaller 3.0 L 14 engines are typically carbureted while the larger 8.1 and 8.2 L V8 engines are
typically fuel injected. Our estimate is that about 25-30 percent of V6 engines and 70-80 percent
of the 5.0 - 6.2L V8 engines are currently sold with fuel injection. For the purpose of this
analysis we anticipate that all SD/I engines will need to be fuel injected to meet the proposed
emission standards. Fuel injection allows better control of the air-to-fuel ratio in the engine and
exhaust for better emission design control and catalyst efficiency.
We consider the use of a port fuel-injection system for this analysis, which refers to
individual injectors located at each intake port in the engine. In addition to the injectors, this
system includes a fuel rail, pressure regulator, electronic control module, manifold air pressure
and temperature sensors, a high pressure fuel pump, a throttle assembly, a throttle position
sensor, and a magnetic crankshaft pickup for engine speed. We also consider a cool fuel system
to prevent the occurrence of vapor lock in the fuel lines. Table 6.4-1 presents the incremental
costs of a port fuel-injection system compared to a carburetor-based fuel system. Because this
technology is widely used today, we include fixed costs for final calibrations as part of the cost
of certification and compliance in Section 6.4.4.
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Draft Regulatory Impact Analysis
Table 6.4-1: Projected Incremental Hardware Costs for Controlled Port Fuel Injection
Hardware Cost to Manufacturer
carburetor
injectors
pressure regulator
fuel filter
intake manifold
fuel rail
throttle assembly (w/ position sensor)
cool fuel system (w/ pump)
electronic control module
air intake temperature sensor
manifold air pressure sensor
crank position sensor
wiring/related hardware
Total Incremental Hardware Cost
Engine Manufacturer Markup
labor at $28/hr
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
3.0L 14
($140)
$68
$15
$1
$14
$80
$150
$115
$70
$5
$14
$16
$80
$488
$3
$1
$143
$24
$659
4.3L V6
($145)
$102
$15
$1
$25
$80
$150
$120
$65
$5
$14
$16
$80
$528
$4
$2
$155
$26
$715
5.0L V8
($145)
$136
$15
$1
$25
$80
$150
$120
$65
$5
$14
$16
$80
$562
$4
$2
$165
$28
$760
5.7L V8
($145)
$136
$15
$1
$30
$80
$150
$120
$65
$5
$14
$16
$80
$567
$4
$2
$166
$28
$767
8.1L V8
($145)
$160
$15
$1
$40
$80
$60
$120
$60
$5
$14
$16
$80
$506
$4
$2
$148
$25
$685
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Costs of Control
6.4.2 Exhaust Gas Recirculation
We do not anticipate that manufacturers will use exhaust gas recirculation (EGR) to meet
the proposed exhaust emission standards. However, in developing this proposal, we considered
the option of a standard based on emission reductions possible through the use of EGR. This
analysis is reflected in our alternatives discussion in Chapter 11. For this analysis, we consider
an EGR system with a valve, plumbing, and modification to the intake manifold. Table 6.4-2
presents incremental variable costs of a controlled engine with EGR compared to an
uncontrolled engine with port fuel injection and no EGR.
Table 6.4-2: Projected Incremental Hardware Costs for Exhaust Gas Recirculation
Hardware Cost to Manufacturer
intake manifold
exhaust gas recirculation
exhaust manifold
oxygen sensors
Total Incremental Hardware Cost
Engine Manufacturer Markup
labor at $28/hr
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
3.0L 14
$5
$25
$2
$17
$49
$1
$0
$15
$2
$67
4.3L V6
$5
$25
$5
$34
$69
$1
$0
$20
$3
$94
5.0L V8
$10
$25
$5
$34
$74
$1
$0
$22
$4
$101
5.7L V8
$10
$25
$5
$34
$74
$1
$0
$22
$4
$101
8.1L V8
$10
$25
$5
$34
$74
$1
$0
$22
$4
$101
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Draft Regulatory Impact Analysis
6.4.3 Catalysts
We anticipate that manufacturers will use small three-way catalysts to meet the proposed
SD/I exhaust emission standards. A catalyst will likely be placed in the riser of each exhaust
manifold upstream of where the water and exhaust gases mix. Catalyst sizes and configurations
are based on the developmental catalyst efforts on SD/I engines discussed in Chapter 4. Costs
are included to modify the exhaust manifolds for packaging of the catalyst. We believe these
catalysts will be used in conjunction with port fuel injection and closed-loop electronic control.
Therefore, we include the cost of an oxygen sensor upstream of each catalyst. The costs in
Table 6.4-3 are presented incremental to an open-loop port fuel injection.
Table 6.4-3: Projected Incremental Hardware Costs for Catalytic Control
Catalyst Unit Price
catalyst volume (L) (each)
number of catalysts
substrate diameter (cm)
substrate
ceria/alumina
Pt/Pd/Rd
can (18 gauge SS)
Total Material Cost
labor at $28/hr
labor overhead at 40%
supplier markup at 29%
Manufacturer Price per Unit
Hardware Cost to Manufacturer
catalysts
oxygen sensors
exhaust manifold
Total Incremental Hardware Cost
Engine Manufacturer Markup
labor at $28/hr
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
3.0L 14
1.00
1
9.5
$8
$11
$28
$3
$51
$5
$2
$17
$74
$74
$17
$10
$101
$2
$1
$30
$5
$139
4.3L V6
0.75
2
8.3
$7
$9
$21
$3
$39
$5
$2
$13
$59
$119
$34
$20
$173
$1
$0
$50
$9
$233
5.0L V8
0.88
2
9.0
$7
$10
$25
$3
$45
$5
$2
$15
$66
$132
$34
$20
$186
$1
$0
$54
$9
$251
5.7L V8
1.00
2
9.5
$8
$11
$28
$3
$51
$5
$2
$17
$74
$148
$34
$25
$207
$1
$0
$60
$10
$279
8.1L V8
1.40
2
11.0
$10
$16
$39
$4
$69
$5
$2
$22
$98
$195
$34
$30
$259
$1
$0
$76
$13
$349
As discussed above, we do not include research and development costs in our fixed costs
for SD/I engines. However, we do include tooling costs that would be associated with ramping
up production of California engines for the entire United States. These tooling costs are
presented in Table 6.4-4.
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Costs of Control
Table 6.4-4: Projected Incremental Tooling Costs for Catalytic Control
Fixed Costs to Engine Manufacturer
tooling
units/year
years to recover
fixed costs/unit
Fixed Costs to Engine Marinizer
tooling
units/year
years to recover
fixed costs/unit
Total Incremental Fixed Costs
3.0L 14
$30,000
15,000
5
$1
$35,000
2,000
5
$5
$5
4.3L V6
$35,000
15,000
5
$1
$45,000
2,000
5
$6
$6
5.0L V8
$40,000
15,000
5
$1
$50,000
2,000
5
$7
$7
5.7L V8
$40,000
15,000
5
$1
$55,000
2,000
5
$7
$8
8.1L V8
$45,000
15,000
5
$1
$55,000
1,000
5
$14
$15
6.4.4 Certification and Compliance
We estimate that certification costs for SD/I engines would come to about $130,000 per
engine family. We expect that manufacturers would combine similar engines into the same
family. The above certification cost estimate allows for two months of R&D for each engine
family as part of the certification process. This would include two engineers and three
technicians and the corresponding testing costs for the two-month period. Unless engine designs
were significantly changed, engine families could be recertified each year using carryover of this
original test data. This cost is therefore amortized over five years of engine sales with an
average volume of 2,000 engines per family. The resulting cost is $13 per engine.
6.4.5 Operating Cost Savings
We anticipate that manufacturers will convert their remaining carbureted engines to fuel
injection to meet the proposed standards. We believe this will result in fuel savings because of
the better fuel control offered by fuel injection compared to carburetion. The fuel consumption
rates we use for carbureted and fuel injected SD/I engines and their derivation are described in
more detail in the docket.36 We use the price of gasoline discussed earlier in this chapter.
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Draft Regulatory Impact Analysis
Table 6.4-5: Projected Fuel Savings for SD/I Engines
Annual Per-Engine Gallons Consumed
Average Life (years)
Anticipated Reduction in Fuel Consumption
Lifetime Gallons Saved
Lifetime Cost Savings
Discounted Cost Savings (7%)
228
19.7
2.3%
103
$186
$106
6.4.6 Total SD/I Engine Costs
We expect that SD/I engine manufacturers would use catalytic converters and electronic
fuel injection to meet the proposed standards. In 2003, about 60 percent of SD/I engines were
sold with electronic fuel injection. This estimate is based on confidential sales information
submitted to the California Air Resources Board by SD/I manufacturers certifying to the 2003
California exhaust emission standards. The manufacturers who certified in California represent
more than 90 percent of U.S. sales of SD/I engines. Manufacturers have indicated to us that they
are moving in the direction of selling more fuel-injected engines and using carburetors only on
their low-cost "introductory" engines. For this cost analysis, we use the projected technology
mix for 2009 from the NONROAD model which projects that about 85 percent of SD/I engines
sold will be fuel-injected. Table 6.4-6 presents our estimates of the sales mix between carbureted
and fuel-injected SD/I engines.
Table 6.4-6: Baseline Technology Mix for SD/I Engines
3.0LI-4
4.3LV-6
5.0LV-8
5.7LV-8
8.1LV-8
high performance
2003 MY California Certification
Carbureted
100%
75%
40%
10%
100%
~
Fuel Injection
0%
25%
60%
90%
0%
~
Projected 2009 Baseline
Carbureted
50%
20%
5%
0%
0%
50%
Fuel Injection
50%
80%
95%
100%
100%
50%
We developed the per-engine costs by assigning costs for catalysts to all SD/I engines
and costs for electronic fuel injection for engine models that are projected to be carbureted in
2009. As discussed above, our cost estimates include both variable and fixed costs, and we
distinguish between near-term and long-term costs. Because our analysis amortizes fixed costs
over 5 years, the long-term costs are made up of variable costs only. These variable costs are
lower in the long term due to the learning effect discussed above. Table 6.4-7 presents these
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Costs of Control
average per-engine cost estimates. To develop high-performance engine cost we considered that
larger catalysts would be needed, even than the 8.1L engine, due to higher exhaust flow rates.
Therefore, the variable costs were increased by 37 percent to account for this increase. Fixed
costs were based on an engine family size of 50 engines, compared to 2,000 engines for
traditional SD/I engines.
Table 6.4-7: SD/I Per-Engine Cost Estimates (Without Fuel Savings)
SD/I Aggregate
3.0L
4.3L
5.0L
5.7L
8.1L
high performance
Short Term (years 1-5)
Fixed
$20
$18
$19
$20
$21
$28
$95
Variable
$342
$465
$377
$297
$279
$349
$825
Total
$362
$483
$396
$317
$300
$377
$920
Long Term (years
6-10)
$274
$372
$301
$238
$223
$279
$672
6.4.7 SD/I Aggregate Costs
Aggregate costs are calculated by multiplying the per-engine cost estimates described
above by projected engine sales. Engine sales are based on estimates supplied by the National
Marine Manufacturers Association (www.nmma.org) and projections for future years are based
on the growth rates in the NONROAD model. Fuel consumption reductions are calculated using
the NONROAD based on population estimates. These population estimates in the NONROAD
model are similar to those estimated by NMMA. A description of the sales and population data
and our analysis of the data is available in the docket.37 Table 6.4-8 presents the projected costs
of the proposed rule over a 30-year time period with and without the fuel savings that would be
expected from meeting the exhaust emission standards. Fuel savings from the proposed
evaporative emission standards are not included in this table, but they are presented separately
below.
At a 7 percent discount rate, over 30 years, the estimated annualized cost to
manufacturers for SD/I exhaust emission control is $33 million. The corresponding estimated
annualized fuel savings due to more efficient engine controls is $10 million. At a 3 percent
discount rate, over 30 years, the estimated annualized cost to manufacturers for SD/I exhaust
emission control is $31 million. The corresponding estimated annualized fuel savings due to
more efficient engine controls is $11 million.
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Draft Regulatory Impact Analysis
Table 6.4-8: Projected 30-Year Aggregate Cost Stream for SD/I Engines
Year
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
Without Fuel Savings
$34,371,313
$34,619,275
$34,873,594
$35,127,914
$35,382,234
$26,919,578
$27,111,689
$27,301,399
$27,491,109
$27,680,818
$27,870,528
$28,060,238
$28,249,948
$28,439,658
$28,629,367
$28,819,077
$29,008,787
$29,199,697
$29,390,608
$29,581,518
$29,772,429
$29,963,339
$30,154,250
$30,345,160
$30,536,071
$30,726,981
$30,917,892
$31,108,802
$31,299,713
$31,490,623
With Fuel Savings
$33,494,477
$32,867,058
$32,183,227
$31,506,139
$30,816,636
$21,417,165
$20,680,689
$19,951,604
$19,238,380
$18,545,390
$17,864,335
$17,188,875
$16,506,937
$15,839,760
$15,182,967
$14,541,220
$13,918,790
$13,321,013
$12,751,094
$12,230,592
$11,947,322
$11,732,535
$11,567,788
$11,435,606
$11,325,500
$11,233,060
$11,157,682
$11,094,904
$11,044,775
$11,006,958
6.5 Evaporative Emission Control Costs for Small SI Equipment
This section presents our cost estimates for meeting the proposed evaporative emission
standards for land-based equipment using small spark-ignition engines.
In our analysis of the costs of the proposed evaporative emission standards for Small SI
equipment, we consider the approximately 250 equipment types used in the NONROAD model
to determine emission inventories. These equipment types are then aggregated into the five
engine classes, with each class divided by general equipment types and between residential and
commercial applications. For each of these aggregate categories, we determine weighted
average hose lengths and tank sizes which we use as inputs to our cost calculations. These
inputs are presented in more detail in the evaporative emission inventory discussion in Chapter
3. This discussion presents our cost estimates as a function of hose length and tank size. In
addition, we present examples of costs for four typical Small SI equipment configurations which
include a handheld (HH) configuration, a walk-behind mower (WBM), and two other non-
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Costs of Control
handheld (NHH) configurations. These configurations, which are presented in Table 6.5-1, are
based on average tank sizes and hose lengths used in our inventory model (see Chapter 3).
Although these typical configurations do not, by any means, represent all of the equipment types
included in our cost calculations, they should give a good indication of how we performed our
analysis.
Table 6.5-1: Typical Small SI Equipment Configurations
Fuel Tank Capacity (gallons)
Fuel Tank Material*
Fuel Tank Molding Process
Fuel Tank Weight (Ibs.)
Fuel Hose Length (in.)
Fuel Hose Inner Diameter (in.)
HH
0.25
HOPE
IM/BM
0.6
4
0.125
WBM
0.5
HOPE
IM/BM
0.8
8
0.25
NHH#1
2
HOPE
IM/BM
1.8
24
0.25
NHH #2
5
XLPE
RM
5.9
36
0.25
* HDPE = high-density polyethylene, XLPE = cross-link polyethylene
* IM = injection-molded, BM = blow-molded, RM = rotational-molded
The fuel tank weights are based on measurements made in our lab on many of the fuel
tanks that were included in our evaporative emission test programs. The higher weight to
capacity ratio of the smaller fuel tank is due to the smaller surface to volume ratio and due to
extra structural components often molded as part of the fuel tanks. We use the fuel tank weight
to determine costs of material changes. The method used to mold the fuel tank and material used
affect the permeation control strategies that may be used. This effect is discussed below.
Note that some handheld equipment has structurally-integrated constructions where the
fuel tank is part of the structure of the equipment. These fuel tanks are typically made out of
nylon 6 with up to 30 percent fiberglass reinforcement. Data in Chapter 5 suggest that these fuel
tanks would be able to meet the proposed tank permeation standards without changing the fuel
tank material.
6.5.1 Hose Permeation
Barrier fuel hose incremental costs estimates are based on costs shared confidentially by
component manufacturers. These costs are supported by the costs of existing products used in
other nonroad and automotive applications.38'39>40 For baseline hose, we consider nitrile rubber
hose such as that used to meet SAE J30 R7 recommendations. For handheld equipment, we
consider the baseline hose to be injected-molded rubber hose for structurally-integrated
constructions and clear elastomeric tubing for other equipment
For this analysis, we considered three primary approaches to reducing permeation from
fuel hoses. The first was the use of thermoplastic fuel lines such as those used in automotive
applications. The incremental cost of these fuel lines is about $0-0.10/ft compared to typical
hose used on Small SI equipment. However, there have been concerns expressed in the past by
manufacturers that this fuel line is not flexible or durable enough for small nonroad applications.
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Draft Regulatory Impact Analysis
Two other approaches are using thermoplastic or thermoelastomer barrier materials in the
fuel hose construction. Our estimate is that thermoplastic fuel lines, such as Teflon or THV800,
would result in an incremental cost to the manufacturer of about $0.75-0.85 per foot.
Manufacturers have expressed in the past that they would have to upgrade their fuel clamps for
the use of thermoplastic barrier hose. Therefore, we include an incremental cost for the two
clamps totaling $0.10. Manufacturers have recently shared with us that they believe the
proposed standards can be met through the use of a lower cost approach. In this approach, the
barrier layer is made of a thermoelastomer such as FKM. Our estimate of the incremental cost
for this approach is $0.20-0.30 per foot. Although the high flexibility of thermoelastomers such
as FKM may allow manufacturers to use existing hose clamps, we also include the hose clamp
cost due to the uncertainty of how manufacturers will construct their equipment with the new
hose.
In some handheld applications, the fuel lines are molded in intricate custom shapes rather
than extruded like traditional hoses. In these designs, a section of the fuel line is inside the fuel
tank while the remainder is external to the fuel tank. In addition, a vent line may be molded into
the same part. Because the tanks are typically sealed with a one way valve on the vent, the vent
lines are exposed to saturated vapor. The fuel lines may be formed from molded cured rubber
such as NBR or injection-molded out of a rubberized plastic such as Alcryn. A low permeation
approach would be to mold the fuel lines out of FKM which is a thermoelastomer used in other
fuel line applications. Based on a sample of six fuel lines (two of which included vent lines) we
got an average weight of 11 grams (0.025 Ibs.). Based on cost estimates of $1.00/lb. for NBR
and $10-15/lb. for FKM, we get a cost estimate of $0.25 to $0.35 per fuel line. Manufacturers
have raised the concern that if a new material is used, that they may need to modify their hose
connectors to make sure that the hose does not pull off the barbs. To account for this, we include
a $0.10 cost for the addition of clamps or hose connector modifications.
Table 6.5-2 presents the estimated incremental costs of low permeation hose for four
typical equipment configurations. These costs include the markup discussed above for overhead
and profit. Because these hose constructions are established technology, we consider the short
and long-term costs to be the same. We believe the proposed standards can be achieved using a
thermoelastic barrier and therefore use these costs in our analysis.
Table 6.5-2: Fuel Line Permeation Cost Estimates for Typical Small SI Equipment
thermoplastic barrier hose
thermoelastic barrier hose
thermoelastic molded fuel line
HH
4", 1/8" ID
$0.54
$0.28
$0.48
WBM
8", 1/4" ID
$0.86
$0.34
NA
NHH#1
2 ft, 1/4" I.D.
$2.32
$0.77
NA
NHH#2
3 ft, 1/4" I.D.
$3.42
$1.10
NA
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Costs of Control
6.5.2 Tank Permeation
As discussed in earlier chapters, plastic fuel tanks for Small SI equipment are constructed
in one of three primary molding processes: blow-molding, injection-molding, and rotational
molding. Blow-molded tanks are primarily made of high-density polyethylene (HDPE),
injection-molded tanks are primarily HDPE or nylon, and rotational molded tanks are primarily
cross-link polyethylene (XLPE). Because the molding process can affect the permeation control
approaches available, we discuss the technologies for each approach individually.
6.5.2.1 All HDPE fuel tanks
Surface treatments can be used to reduce permeation from HDPE fuel tanks, whether
they are blow-molded, injection-molded, or rotational-molded. Our surface treatment cost
estimates are based on price quotes from a companies that specialize in fluorination41 and
sulfonation.42 In the fluorination process, costs are based on the number of fuel tanks that will fit
into the fluorination treatment chamber. Therefore, costs are higher for larger fuel tanks,
because less tanks will fit in the chamber. The price sheet referenced for our fluorination prices
assumes rectangular shaped containers. These fuel tanks would stack easily in the fluorination
treatment chamber with little wasted space. However, tor irregular shaped fuel tanks, less fuel
tanks would fit in the treatment chamber due to dead space between the tanks when they are
placed in the support baskets in the chamber. To account for this inefficiency with typical
shaped fuel tanks, we consider a void space equal to about 25 percent of the volume of the fuel
tank. For handheld equipment, we consider a void space of 100 percent because of the
structurally-integrated nature of many tanks.
For sulfonation, the shape of the fuel tanks is less of an issue because the treatment
process is limited only by the spacing on the production line which is roughly the same for the
range of fuel tank sizes used in Small SI equipment. These prices do not include the cost of
transporting the tanks; we estimated that shipping, handling and overhead costs would be an
additional $0.03 to $0.76 per fuel tank depending on tank size (using the same void space
estimates as above).43
Manufacturers, with high enough production volumes, could reduce the costs of
sulfonating fuel tanks by constructing an in-house treatment facility. The cost of a sulfonation
production line facility that could treat 150-500 thousand fuel tanks per year (depending on tank
size) would be approximately $800,000.44 This facility, which is designed to last at least 10
years, is made up of a SO3 generator, a scrubber to clean up used gas, a conveyor belt, and
injection systems for the SO3 gas and for the neutralizing agent (ammonia solution). The
manufacturer of this equipment estimates that the operating costs, which includes electricity and
chemicals, would be about 3 cents per tank. We based our costs on a production capacity of
300,000 units per year for handheld tanks and 150,000 units per year for non-handheld tanks. In
the long term, the costs would be based on the full life of the equipment which we estimate to be
10 years for this analysis. Finally, we use a labor rate of $28/hr with a 40 percent markup for
overhead which is consistent with our engine costs above and apply one full time employee to
operation of the sulfonation machine. A manufacturer that sulfonates its fuel tanks in-house
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would not need to pay shipping costs. In the long run, we calculate that this approach will be
less expensive than shipping tanks to an outside facility.
6.5.2.2 Blow-molded fuel tanks
Manufacturers may reduce permeation from blow-molded fuel tanks by blending in a low
permeation material such as ethylene vinyl alcohol (EVOH) with the HDPE. This is typically
known by its trade name, Selar. The EVOH in the plastic forms non-continuous barrier platelets
in the tank during blow-molding that make it harder for fuel to permeation through the walls of
the tank. Using this approach, no changes should be necessary in the blow-molding equipment,
so the costs are based on increased material costs. We used 10 percent EVOH which costs about
$3-4 per pound and 90 percent HDPE which costs about $0.65-0.75 per pound.45 This equates to
a price increase of about $0.35 per pound. We then applied the material weights shown in
Table 6.5-1 to estimate costs per tank for this technology.
For higher production volumes, manufacturers may consider blow molding multi-layer
fuel tanks with continuous barriers. Practically, a new blow-molding machine would be required
because four or five additional injection screws would be necessary for the barrier layer, two
adhesion layers, an additional HDPE layer, and potentially a regrind layer. A machine that could
blow-mold multi-layer tanks would approximately double the price of the blow-molding
machine. For this analysis, we use a mono-layer machine cost of $1,000,000 and a multi-layer
machine cost of $3,000,00046, resulting in an increase in machine cost of $2,000,000. In
addition, tooling costs for each new tank design would be about $50,000. For this analysis we
considered a fuel tank with a material composition of 3 percent EVOH at $3.50/lb, 4 percent
adhesive layer at $l/lb, 45 percent regrind, and the remainder HDPE. Our analysis uses a total
annual production of 80,000-160,000 blow-molded tanks per year, depending on tank size
(smaller sizes would allow more tanks per mold), with 5 different molds. Capital costs are
amortized over 5 years in the short term and 10 years in the long-term (reflecting a 10 year life
of the machine).
6.5.2.3 Injection-molded fuel tanks
The technologies discussed above for blow-molded fuel tanks do not appear to be
feasible for injection-molded fuel tanks. The non-continuous barrier platelet approach does not
work well in this process because of the high shear stresses associated with injection molding.
Multi-layer rotomolded tanks would have to be formed by making separate molds, then fusing
the layers when the tank sides are welded together. While this may be possible, it would be
cumbersome. Barrier treatments would work for fuel tanks injected out of HDPE, but many
handheld tanks are injection molded out of nylon for better thermal resistance. At this time, it
appears that fluorination and sulfonation would not work effectively on nylon tanks. However,
nylon has low permeation on gasoline, and some nylon formulations are capable of meeting the
proposed standards which are based on test fuel with 10 percent ethanol.
The advantages of injection molding are that it has lower tooling costs than blow-
molding and it is a faster molding process than rotational-molding. Although injection-molding
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Costs of Control
does not lend itself well to multi-layer construction, there is another process with similar costs
and production rates called thermoforming which does. Thermoforming entails using sheets of
plastic that are heated and pulled into a mold using vacuum suction. As with injection molding,
two halves are then joined together. In thermoforming, however, the sides are combined while
the plastic is still molten rather than by welding as is used in injection-molding. By using sheets
of extruded multi-layer plastic, thermoforming can be used to produce low-permeation, multi-
layer fuel tanks.
Because the thermoforming process requires extruded sheets, this process requires the
addition of an extruder. A small extruder, which would support several thermoforming machines
considered in this analysis would cost $2-3 million. The thermoforming machine itself would
cost about two-thirds that of an injection molding machine because it has less moving parts (such
as the injection screw). However, we estimate that two thermoforming machines would be
necessary to maintain the cycle time possible with an injection molding machine. At the same
time, hot plate welding machines would not be necessary because the tanks halves are assembled
in the thermoforming machine. We use an incremental cost savings of $100,000 for the molding
machine. Mold costs are somewhat lower for thermoforming as well because they are made of
aluminum rather than hardened steel. We estimate that a four-cavity injection mold would cost
about $60-80,000 while a four-cavity thermoforming mold would cost $20-30,000. For this
analysis we use a production of 300,000 tanks per year using 5 different molds. In the short
term, we amortize the fixed costs over 5 years, while in the long term we use 10 years to
represent the full life of the machines. Incremental material costs are based on 3 percent EVOH
and 4 percent adhesion material to create the barrier layer.
Another option would be to mold the entire fuel tank of a low permeation material such
as an acetal copolymer, or a thermoplastic polyester. These materials have list prices in the
range of about $1-2 per pound which is about double the material cost of HDPE, but comparable
to the cost of nylon.47 In addition, these fuel tanks could be made out of metal, which does not
permeate. For larger marine fuel tanks, metal tanks are available that cost about 25-30 percent
more than plastic fuel tanks (made under low volume construction). Private conversations with
Small SI equipment manufacturers suggest that making small fuel tanks out of metal could
increase the cost of the tanks for Small SI equipment by 200-300 percent and would limit the
possibility of constructing complex designs.
6.5.2.4 Rotational-molded fuel tanks
Many larger fuel tanks are rotationally molded. This process is more cost-effective for
smaller production volumes than blow-molding or injection-molding because of the lower
tooling costs for new tank designs. However, this process is slower which limits its usefulness
for large production volumes. Typically, rotational-molded fuel tanks manufactured for Small SI
equipment are made of cross-link polyethylene (XLPE). Although XLPE is more expensive than
HDPE which may also be used in the rotational-molding process, it is considered to be more
impact resistant than HDPE. This is important because the rotational molded fuel tanks are often
larger fuel tanks mounted on the outside of the equipment where it could be exposed to impacts
such as stepping, thrown rocks, branches, etc.
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Draft Regulatory Impact Analysis
As discussed in Chapter 5, neither sulfonation or fluorination has been demonstrated to
be successful in creating a barrier on XLPE that would meet the proposed standards. Therefore,
we look to multi-layer approaches for our cost estimates. In the rotational-molding process, fuel
tanks may be formed with two layers. The traditional method is to add the first material to the
mold prior to entering the oven, and once that shell forms to add a second material through the
use of a drop box in the mold. Depending on the complexity and size of a drop box, it can add
from $1,000 to nearly $9,000 to the cost of the mold.48'49'50 One manufacturer is currently
making multi-layer rotational-molded fuel tanks for use Small SI equipment without the use of a
drop box. Their approach is proprietary, but the material manufacturer is making efforts to
develop an alternative to using a drop box as well.51 For this analysis, we include a $5,000 cost
for a drop box in the short term, but not in the long term. In addition, we do not project that this
process will have an increase on the cycle processing time because the increased heating time is
offset by decreased cooling time. The inner layer could be molded out of an acetal copolymer,
nylon, or even HDPE which could then be surface treated. Typical acetal copolymers cost about
the same as XLPE, although the rotational-molding grade may cost a little more.52 We use a cost
of $1.50/lb. for this acetal copolymer compared to XLPE which is approximately $1.20/lb.
Nylon, which can range in cost from $2 to $6 depending on the grade may also be used in
conjunction with XLPE to provide a permeation barrier. The advantage of nylon is that it bonds
to XLPE better than acetal copolymers. For this analysis, we consider the use of nylon at
$4.00/lb in a fuel tank with a 1 mm barrier and 4-5mm average total wall thickness. We
amortize the fixed cost of the drop boxes over 5 years of production of 1000 tanks per year for
each mold.
Another material is also available for molding an inner layer in rotomolded XLPE fuel
tanks. This material is poly butylene terephthalate cyclic oligimor and is known by the trade
name CBT®. With this material, no drop box is necessary. The CBT is added in the mold with
the XLPE resin. During the molding process, the XLPE shell forms in the mold. Due to
differences in viscosity and temperature properties, the CBT goes to the inside of the fuel tank.
It then polymerizes to form an inner liner. We use a cost of $5/lb. for CBT in this analysis and
use the same barrier thickness as discussed above.
Another technology that has been demonstrated for reducing permeation from XLPE fuel
tanks is a low permeation epoxy barrier. To apply this barrier, an adhesion treatment must first
be performed to increase the fuel tank surface energy so that the epoxy will adhere to the XLPE.
This can be done through a low level fluorination treatment. For this analysis we use the cost of
level 1 fluorination.53 We use the same void space and shipping costs discussed above for our
fluorination cost analysis. The epoxy could be applied by dipping the fuel tank or spraying it on
like paint and then must be cured using UV light. We include a fixed cost of $10,000 for a
volume of 100,000 fuel tanks per year to account for coating and curing equipment. In addition,
we apply the cost of one full time employee to apply the coating and use a labor rate of $28/hr
with a 40 percent markup for overhead which is consistent with our engine costs above. For
traditional epoxies, we estimate that the cost would be $6-7/lb. Manufacturers have commented
that UV-curable epoxy, which could be processed much faster, would cost $12-15/lb.54'55 We
use a cost of $12/lb. for this analysis. Because only a thin coating needed (we use 0.125 mm),
the epoxy layer makes up only about 3 percent of the material of the fuel tank. Because there are
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Costs of Control
benefits to the epoxy coating such as allowing the fuel tank to be painted, there may be an
incentive to use this technology even on HDPE fuel tanks. For that reason, we estimated the cost
for smaller HDPE tanks as well using the same general assumptions except for a larger
production volume of 150,000 tanks per year due to their smaller size.
6.5.2.5 Summary of Fuel Tank Costs per Equipment
Table 6.5-3 summarizes the incremental costs of the fuel tank permeation emission-
control strategies discussed above. For technologies sold by a supplier to the engine
manufacturers, an additional 29 percent markup is included for the supplier's overhead and
profit. Both long-term and short-term costs are presented. The long-term costs account for the
stabilization of the capital investments and the learning curve effect discussed above. We use
the same material and shipping costs for our short-term and long-term estimates because these
cost components are well established with a wide range of applications. As discussed above, for
the multilayer fuel tank constructions, we consider an EVOH barrier for hand-held and Class I
equipment and nylon barrier for Class II equipment.
Table 6.5-3: Tank Permeation Control Cost Estimates for Typical Small SI Equipment
fluorination3'b: short term
long term
sulfonation3'b: short term
long term
non-continuous platelets3
multi-layer3: short term
EVOH long term
multi-layer0: short term
PA 1 1 long term
multi-layer0: CBT
thermo-formingb: short term
long term
acetal-copolymer3'b'°
metal construction3'13'0
epoxy coating3'b'°: short term
long term
HH
0.25 gallons
IM/BM
$0.62
$0.50
$0.64
$0.52
$0.17
$4.13
$2.01
NA
NA
$0.36
$0.20
$0.62
$1.94
$1.26
$1.01
WBM
0.5 gallons
IM/BM
$0.77
$0.63
$1.25
$1.01
$0.22
$4.08
$1.98
NA
NA
$0.53
$0.29
$0.79
$3.87
$1.32
$1.06
NHH#1
2 gallons
IM/BM
$3.10
$2.52
$1.40
$1.16
$0.51
$3.80
$1.75
NA
NA
$1.50
$0.82
$1.82
$5.16
$2.56
$2.08
NHH#2
5 gallons
RM
NA
NA
NA
NA
$5.54
$3.40
$5.77
NA
$2.28
$9.68
$5.69
$4.64
a incremental to traditional
b incremental to traditional
c incremental to traditional
blow-molding
injection-molding
rotational-molding
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6.5.3 Venting Losses
Venting losses are made up of diurnal breathing losses and running losses which are
similar to diurnal emissions except that the heating event is caused by the engine. We are
proposing that equipment manufacturers install systems to capture their running losses by sealing
the fuel tank and venting vapor to the engine intake. For the purpose of our cost analysis, we
consider a system with a purge hose running from the fuel tank to the engine intake (with 2 hose
clamps) that is the same length of the fuel hose. We use a cost of $0.25/ft for the hose and $0.10
each for the two hose clamps. This is consistent with the above cost analysis for low permeation
hose. We also consider a fuel cap redesign to meet the proposed sealing requirements with a one
way valve to prevent a vacuum from occurring in the fuel tank as fuel is drawn out to the engine.
We use a cost of $1 for the valve and cap redesign. Also, we include a cost of $0.10 to account
for a limiting flow orifice in the purge line. Finally, using the labor costs discussed above, we
calculate an incremental assembly labor cost of about $0.20 per engine.
Diurnal emissions could be captured through the use of a carbon canister. The carbon
then could be purged by air drawn into the fuel tank as the fuel cools. This is known as passive
purge. This system would be similar to the running loss control system except that venting
would occur through a canister and the valving would be modified to provide liquid/vapor
separation. This valve would prevent fuel from entering the canister if the equipment were
tipped over. We estimate the cost of a canister to vary based on size ranging from about $2 for a
1 quart tank to about $4 for a five gallon tank. The majority of these canister costs for small fuel
tanks are for the canister, connections, and mounting hardware. As the fuel tank size increases,
the carbon becomes a more significant fraction of the cost. For this analysis, we add the cost of
the canister to the cost of running loss control and include another $0.20 for assembly costs.
Diurnal emissions could be controlled further through an active purge canister system. In
an active purge system, the canister would also be purged by the engine during operation. The
added components of this system compared to the passive purge system would include a line to
the air filter (or separate air filter for the canister breathing line) and a purge valve. This
amounts to an additional cost of $0.15/ft for the air line, $0.20 for two clamps, $1 for the purge
valve, and another $0.20 for assembly.
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Costs of Control
Table 6.5-4: Venting Control Cost Estimates for Typical Small SI Equipment
running loss: short term
long term
passive purge canister* : short term
long term
active purge canister* * : short term
long term
WBM
0.5 gallons
8", 1/4" ID
$2.06
$1.65
$3.07
$2.45
$1.93
$1.54
NHH#1
2 gallons
2 ft, 1/4" ID
$2.32
$1.85
$3.82
$3.06
$2.19
$1.75
NHH#1
5 gallons
3 ft, 1/4" I.D.
$2.51
$2.01
$4.38
$3.51
$2.38
$1.91
* incremental to running loss control
** incremental to passive purge canister
6.5.4 Certification and Compliance
The proposed running loss standards call for manufacturers to certify their running loss
systems based on design rather than requiring emission testing. However, they will still need to
integrate the emission-control technology into their designs and there will be some engineering
and clerical effort need to submit the required information for certification. We expect that in
the early years, plastic fuel tank manufacturers will perform durability and permeation testing on
their fuel tanks for certification. They will be able to carry over this data in future years and will
be able to carry across this data to other fuel tanks made of similar materials and using the same
permeation control strategy regardless of tank size or shape. Typical certification costs may be
spread between the tank manufacturer, hose manufacturer, and equipment manufacturer. For the
sake of this analysis, we combine the tank, hose, and boat certification costs to calculate the total
certification of an average fuel system. We estimate that 90 percent of fuel tank sales in Small
SI equipment are plastic and the remainder are metal.
For the first year we estimate fuel tank durability and certification testing to cost about
$15,000 per tank manufacturer on the assumption that the manufacturer will use the same
materials and permeation control strategy for all of their fuel tanks to reduce costs. Low
permeation fuel lines are largely an established technology. However, we include a cost of
$1,000 to perform certification testing on fuel lines. In addition, we estimate about $10,000 for
engineering and clerical work for the equipment manufacturers.
For handheld equipment manufacturers, we spread these costs over sales of 500,000 units
per year. For handheld and Class I equipment manufacturers, which are integrated
manufacturers, we base the costs on average annual sales per manufacturer. We estimate the
average annual sales to be about 500,000 units for handheld equipment and 100,000 units for
Class I equipment. Generally for Class II equipment, a large number equipment manufacturers
purchase their engines from a smaller number of engine manufacturers. We estimate average
annual sales per year to be 50,000 units for Class II.
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Draft Regulatory Impact Analysis
As with other fixed costs, we amortized the cost over 5 years of sales to calculate per unit
certification costs. Combining these costs, we get average fuel system integration and
compliance costs of about $0.01 for handheld equipment, $0.05 for Class I equipment, and $0.10
for Class II equipment.
6.5.5 Operating Cost Savings
Evaporative emissions are essentially fuel that is lost to the atmosphere. Over the
lifetime of a piece of Small SI equipment, this can result in a significant loss of fuel. The
proposed reduction in evaporative emissions would therefore result in meaningful fuel savings
which can be directly related to operating cost savings based on an average density of 6
Ibs/gallon for gasoline (based on lighter hydrocarbons which evaporate first) and the price of
gasoline described above. Table 6.5-5 presents the estimated fuel savings for Small SI
equipment associated with the proposed evaporative emission standards.
Table 6.5-5: Projected Evaporative Fuel Savings for Small SI Equipment
Evaporative HC Reduced [Ibs/life]
Lifetime Gallons Saved
Lifetime Cost Savings
Average Equipment Life [years]
Discounted Cost Savings (7%)
Handheld
1.4
0.2
$0.41
4.2
$0.40
Class I
4.9
0.8
$1.46
5.3
$1.32
Class II
28.6
4.7
$8.57
5.9
$5.98
6.5.6 Total Small SI Equipment Costs
We expect that Small SI manufacturers will use a variety of technologies to meet the
proposed fuel tank permeation standards. As discussed above, many options are available so the
technologies chosen will depend on the baseline fuel tank construction, the equipment
application, and the manufacturers' particular design philosophies. Hose permeation standards
will likely be met through the use of barrier hose constructions.
For the purpose of this analysis, we divided Small SI equipment into 23 categories to
better quantify differences in costs that may be associated with different equipment applications.
Earlier in this chapter, engine costs are presented as a function of design life. However, we
believe evaporative emission costs are more a function of the application than the design life due
to the differences in hose lengths and tank sizes and constructions. Manufacturers would not
likely design a less robust fuel system for equipment used with lower hour engines. Table 6.5-6
presents our assessment of the mix of the fuel system constructions used today. This assessment
is based on the NONROAD 2005 model and on confidential information supplied by Small SI
equipment manufacturers.
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Costs of Control
Table 6.5-6: Baseline Technology Mix for Small SI Equipment
Equipment Class
Fuel Line Description
Length ft*
construction
Fuel Tank Construction
gallons
material/process* *
Handheld Equipment
Class III commercial
Class III residential
Class IV commercial
Class IV residential
Class V
0.25
0.25
0.33
0.33
0.50
rubber hose
rubber hose
6% molded line
24% molded line
52% molded line
0.9
0.3
0.4
0.3
0.5
HOPE
HOPE
6% Nylon/94% HOPE
24% Nylon/76% HOPE
52% Nylon/48% HOPE
Class I Equipment
ag/const/gen ind/mat hand
commercial mowers
residential mowers
com. other L&G
res. other L&G
pumps/comp/press. wash
snow equipment
utility /rec. vehicles
welders/generators
0.72
0.72
0.62
0.72
0.62
0.72
0.63
0.72
0.72
rubber hose
rubber hose
rubber hose
rubber hose
rubber hose
rubber hose
rubber hose
rubber hose
rubber hose
1.6
0.8
0.4
1.1
0.6
0.8
0.3
3.6
0.8
100%IM
90%IM/10%BM
100%IM
90%IM/10%BM
100%IM
100%IM
100%IM
100%IM
100%IM
Class II Equipment
ag/const/gen ind/mat hand
commercial mowers
residential mowers
com. other L&G
res. other L&G
pumps/comp/press. wash
snow equipment
utility /rec. vehicles
welders/generators
3.6
6.5
3.2
1.5
1.1
2.6
1.2
2.7
3.8
rubber hose
rubber hose
rubber hose
rubber hose
rubber hose
rubber hose
rubber hose
rubber hose
rubber hose
5.4
4.7
2.6
1.2
5.0
4.7
0.7
3.9
6.0
60% EM/40% RM
60% EM/40% RM
70/18/12%IM/BM/RM
60% EM/40% RM
70/18/12%IM/BM/RM
60% EM/40% RM
60% EM/40% RM
60% EM/40% RM
60% EM/40% RM
* we use 1/8" I.D. for handheld and 1/4" I.D. for non-handheld hose
** IM = injection molded HOPE, BM = blow-molded HOPE, RM = rotational-molded XLPE
We base our fuel tank costs on several technologies. In our cost analysis for handheld
engines, we model costs based on fluorination for HDPE tanks, but we do not apply costs to
tanks that are molded out of nylon as these tanks would likely meet the proposed standards
today. For non-handheld equipment, we split the costs of permeation control of injected molded
FfDPE fuel tanks 50/50 between fluorination and converting to multi-layer thermoformed
constructions with an EVOH barrier. For blow-molded fuel tanks, we base our costs on using a
multi-layer blowmolded construction with an EVOH barrier. For rotational-molded XLPE fuel
tanks, we base our costs on rotational-molding a nylon layer in the tank.
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For fuel line permeation, we distinguish between the costs for traditional hose versus
molded fuel lines. Fuel hose costs are based on using a fluoroelastomer barrier within the
traditional construction. For molded fuel lines, we base the costs on molding the parts
completely out of a high-grade fluoroelastomer. We do not apply costs to fuel lines used in cold-
weather equipment.
In the case where current equipment designs are such that the fuel in the tank does not
heat up substantially during operation, equipment manufacturers would not need to add
additional hardware for running loss control. However, we are not able to quantify what fraction
of the equipment population this represents at this time. Therefore, we are applying the cost of
the running loss system described above for all non-handheld equipment in our analysis. This
cost approach presents a somewhat conservatively high cost of control for running loss. This
running loss control system would also control diffusion from Small SI equipment. In some
cases, manufacturers may choose to move the fuel tank further away from heat sources such as
the engine or hydraulic system to meet the proposed running loss requirement (or insulate the
tank). Presumably, manufacturers would not choose this option unless it were less expensive
than the running loss control system described above. Therefore, we are not attempting to
estimate the range of approaches that manufacturers may take to meet the proposed running loss
requirements.
As discussed above, our cost estimates include both variable and fixed costs, and we
distinguish between near-term and long-term costs. Because our analysis amortizes fixed costs
over 5 years, the long-term costs are generally made up of variable costs only. The exception to
this is fuel tank permeation control strategies where more expensive molding equipment is used.
We assume an equipment life of 10 years, so in the long term, the amortized additional cost of
the molding equipment is half, on average, of the short-term amortized cost over 5 years (5 years
of amortized payments/10 years of equipment life = l/2). In addition, variable costs are lower in
the long term due to the learning effect discussed in Section 6.1. Table 6.5-7 presents these
average per-engine cost estimates.
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Costs of Control
Table 6.5-7: Small SI per Equipment Cost Estimates (Without Fuel Savings)
Handheld aggregate
tank permeation
hose permeation
Class I aggregate
tank permeation
hose permeation
running loss
Class II aggregate
tank permeation
hose permeation
running loss
Short Term (years 1-5)
Fixed
$0.01
$0.01
$0
$0.47
$0.45
$0.02
$0
$1.25
$1.20
$0.04
$0
Variable
$0.81
$0.62
$0.19
$2.71
$0.32
$0.33
$2.05
$5.68
$2.08
$1.09
$2.51
Total
$0.82
$0.63
$0.19
$3.16
$0.75
$0.35
$2.05
$6.90
$3.26
$1.13
$2.51
Long Term (years 6-10)
Fixed
$0
$0
$0
$0.19
$0.19
$0
$0
$0.68
$0.68
$0
$0
Variable
$0.69
$0.50
$0.19
$2.10
$0.26
$0.20
$1.64
$4.62
$1.66
$0.96
$2.00
Total
$0.69
$0.50
$0.19
$2.29
$0.45
$0.20
$1.64
$5.30
$2.34
$0.96
$2.00
6.5.7 Small SI Equipment Aggregate Costs
Aggregate costs are calculated by multiplying the per-engine cost estimates described
above by projected equipment sales. Fuel savings are calculated directly from the projected HC
reductions due to the proposed evaporative emission standards. Table 6.5-8 presents the
projected costs of the proposed rule over a 30-year time period with and without the fuel savings
associated with reducing evaporative emissions.
At a 7 percent discount rate, over 30 years, the estimated annualized cost to
manufacturers for Small SI evaporative emission control is $67 million. The estimated
corresponding annualized fuel savings due to control of evaporative emissions from Small SI
equipment is $52 million. At a 3 percent discount rate, the estimated annualized cost to
manufacturers for Small SI evaporative emission control is $70 million. The estimated
corresponding annualized fuel savings due to control of evaporative emissions from Small SI
equipment is $58 million.
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Draft Regulatory Impact Analysis
Table 6.5-8: Projected 30-Year Aggregate Cost Stream for Small SI Evap
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
Without Fuel Savings
Handheld
$-
$5,714,115
$5,909,315
$6,017,988
$7,848,826
$7,981,700
$6,909,877
$6,922,632
$7,034,855
$7,147,090
$7,259,067
$7,371,143
$7,483,470
$7,595,660
$7,707,763
$7,819,853
$7,931,999
$8,044,212
$8,156,448
$8,268,656
$8,380,840
$8,493,060
$8,605,303
$8,717,528
$8,829,741
$8,941,949
$9,054,168
$9,166,396
$9,278,617
$9,390,834
$9,503,051
Class I
$3,869,095
$3,938,646
$4,008,024
$4,080,278
$34,157,324
$32,774,886
$33,321,924
$33,866,041
$34,402,748
$26,950,398
$27,372,435
$27,799,282
$28,223,637
$28,646,477
$29,066,350
$29,489,883
$29,912,857
$30,337,439
$30,765,267
$31,192,359
$31,618,433
$32,045,711
$32,473,046
$32,900,804
$33,328,357
$33,755,498
$34,182,354
$34,609,570
$35,036,864
$35,464,338
$35,891,721
Class II
$6,281,721
$6,394,682
$6,508,249
$39,786,661
$40,469,354
$39,835,064
$40,503,217
$41,167,585
$33,342,748
$33,879,410
$34,414,535
$34,954,723
$35,491,162
$36,027,436
$36,559,874
$37,095,737
$37,631,938
$38,171,542
$38,711,628
$39,250,255
$39,788,258
$40,327,667
$40,867,213
$41,407,443
$41,946,957
$42,485,978
$43,024,838
$43,564,162
$44,103,498
$44,643,012
$45,182,425
With Fuel Savings
Handheld
$-
$5,480,395
$5,230,762
$4,942,678
$6,193,002
$5,806,851
$4,336,640
$4,075,983
$3,968,662
$3,967,964
$3,997,894
$4,043,702
$4,098,612
$4,158,860
$4,219,200
$4,279,643
$4,340,208
$4,400,839
$4,461,480
$4,522,093
$4,582,681
$4,643,307
$4,703,955
$4,764,584
$4,825,202
$4,885,815
$4,946,439
$5,007,071
$5,067,698
$5,128,319
$5,188,941
Class I
$2,982,585
$2,097,799
$1,225,996
$415,185
$25,627,296
$20,174,259
$17,817,514
$16,541,314
$15,570,529
$6,863,628
$6,516,375
$6,346,214
$6,262,715
$6,230,543
$6,236,111
$6,281,352
$6,346,064
$6,412,326
$6,478,674
$6,544,241
$6,608,795
$6,674,550
$6,740,348
$6,806,591
$6,872,622
$6,938,242
$7,003,562
$7,069,255
$7,135,021
$7,200,976
$7,266,812
Class II
$4,213,867
$1,977,749
$(258,757)
$25,506,408
$19,923,826
$14,024,588
$10,833,852
$8,032,827
$(2,641,523)
$(4,071,321)
$(5,142,350)
$(5,931,671)
$(6,542,467)
$(6,972,441)
$(7,317,102)
$(7,598,592)
$(7,856,488)
$(8,091,169)
$(8,313,604)
$(8,526,931)
$(8,733,177)
$(8,932,174)
$(9,125,631)
$(9,314,633)
$(9,502,186)
$(9,687,202)
$(9,869,734)
$(10,050,377)
$(10,228,844)
$(10,405,188)
$(10,580,702)
6.6 Costs of Evaporative Emission Controls for Marine Vessels
This section presents our cost estimates for meeting the proposed evaporative emission
standards for marine vessels.
To determine the cost impacts of the proposed evaporative emission standards on marine
fuel systems, we considered three primary marine applications. The first is a porTable fuel tank
with a detachable fuel line and a primer bulb. The second is a personal watercraft vessel. The
third is a larger vessel with an installed fuel tank and fuel lines meeting SAE J1527
specifications. In our cost analysis, we consider a wide range of vessel sizes for each of these
categories. However, to simplify this discussion we only present our cost estimates for the three
typical applications shown in Table 6.6-1. For this illustration, costs are based on vessels with
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Costs of Control
one fuel tank and one engine. Although these typical configurations do not, by any means,
represent all of the vessel types included in our cost calculations, they should give a good
indication of how we performed our analysis.
Table 6.6-1: Typical Marine Vessel Fuel System Configurations
Fuel Tank Capacity (gallons)
Fuel Tank Material*
Fuel Tank Molding Process
Fuel Tank Weight (Ibs.)
Fuel Hose: Length (ft.)
Inner Diameter (in.)
Vent Hose: Length (ft.)
Inner Diameter (in.)
Fill Neck: Length (ft.)
Inner Diameter (in.)
PorTable Tank
6
HOPE
blow-molded
4.4
6, primer bulb
1/4
-
-
-
-
PWC
17
HOPE
blow-molded
12
5.7
1/4
2
1/4
1.9
1.5
Installed Tank
57
XLPE
rotational-molded
55
9.9
3/8
8.0
5/8
10.1
1.5
* HDPE = high-density polyethylene, XLPE = cross-link polyethylene
Fuel tank weights are based on measurements of fuel tanks used in our permeation testing
and are used to determine material costs. XLPE fuel tanks are typically thicker walled; thus they
typically weigh more per gallon of capacity. Fuel hose lengths are based on conversations with
(and confidential business information from) boat builders and fuel system suppliers. This data
is within the range of hose lengths included in the written comments made by one boat builder
on our earlier proposal.56
6.6.1 Hose Permeation
There are several grades of fuel system hose used in marine applications. For sterndrive
and inboard (SD/I) applications, Title 33 of the Code of Federal Regulations, Part 183 defines
fuel system requirements. These requirements reference SAE J1527 for fuel hose specifications.
For personal watercraft (PWC), fuel line specifications are defined in SAE J2046. For
outboards, no fuel hose specifications exist. Typically, larger vessels, with installed fuel tanks
use SAE J1527 Class I hose for lines filled with fuel and Class II hose for lines containing fuel
vapor. Inner diameters (ID) of these fuel system lines are typically 3/8" for fuel lines, 5/8" for
vent lines, and 1.5" for fill necks. PWC typically have fuel supply/return hose with a 1/4" ID.
PorTable marine fuel tanks for outboards typically have fuel lines with a 1/4" ID and a primer
bulb. Fill neck hose is made by wrapping several layers of materials over a mandrill and
vulcanizing the rubber in an oven. The remaining fuel lines are typically extruded. Fuel hose
meeting the CFR requirements typically has several layers for durability and flame resistance.
Barrier fuel hose incremental costs estimates are based on costs of existing products used
in marine and automotive applications.57'58'59'60'61 Because the manufacturing process is not
fundamentally changed in adding a barrier layer, this cost is mostly the result of more expensive
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Draft Regulatory Impact Analysis
materials. For 1/4" hose such as used in some small outboards and personal watercraft, we
estimate a cost increase of $0.25/ft for a thermoelastic barrier and $0.85/ft for a thermoplastic
barrier. These costs are consistent with the costs described above for Small SI equipment.
SD/I vessels are required to use marine fuel hose meeting Coast Guard requirements
specified in 33 CFR part 183. This hose is recommended by the American Boat and Yacht
Council for outboard boats not using porTable fuel tanks as well. Marine hose with a nylon
barrier is available today that meets these requirements. The cost differential of traditional
versus marine barrier hose for fuel and vent lines in the market today varies from no cost at all to
more than $1 per foot. One hose distributer stated that they sell both non-barrier and barrier hose
at the same price. They stated that the fuel resistance provided by the barrier layer allows the
hose construction to use a thinner wall and therefore use less rubber. Another hose distributor,
lists about a $1 cost markup for Al barrier hose compared to their Bl marine hose. Note that Bl
hose does not meet the Coast Guard fire requirements for fuel lines and this may be part of the
reason for the cost differential. For this analysis, we use a cost increase of $0.50/ft for fuel hose
and $1.00 for vent hose for vessels with installed fuel tanks. We use a higher incremental cost
for vent hose because this hose typically has a larger diameter, requiring more material.
For VA" fill neck hose, we estimate a cost increase of $2.00/ft. This cost increase is
based on our estimates of material and labor costs. The fill neck hose would be constructed in
the same manner as today except that a thin barrier layer would be included in the multi-layer
construction. One hose distributer advertises barrier fill-neck hose with a price markup of $9 per
foot. However, this cost markup likely represents the high costs typical of special orders where
setup costs must be spread over low hose production. Currently, little or none of this hose is
purchased by boat builders. Our price estimate is more consistent with differences in cost for
barrier versus non-barrier chemical hose manufactured in the same manner.
We do not expect the addition of a barrier layer to affect the flexibility of the hose
because marine hose is already fairly stiff and because the barrier layer is very thin and flexible.
In fact, the barrier hose samples we tested appeared a little more flexible than the baseline hose
because less wall thickness was needed for permeation control. Therefore, we believe special
hose clamps or fittings will typically be required.
Primer bulbs are typically formed from molded cured rubber such as NBR or injection-
molded out of a rubberized plastic such as Alcryn. Primer bulbs could also be molded from
FKM which is a fluoroelastomer used in fuel line applications. Primer bulbs typically weigh
between 0.1 and 0.2 Ibs, nitrile costs about $1.00/lb and FKM costs about $10-15/lb depending
on the level of fluorine in the material. If the whole primer bulb was molded out of FKM, it
would increase the material cost by about $1.50-2.00 per primer bulb. Alternatively,
manufacturers could save on material costs by injection molding an inner layer of Alcryn and
curing a coating of FKM over this shell. Using a higher grade of FKM ($15/lb) could help
minimize the amount of the fluoroelastomer needed. For the multi-layer design, we assume
about 30-50 percent of the material would be FKM which results in a material cost increase of
about $0.90 per primer bulb.
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Costs of Control
Table 6.6-2 presents our estimates of incremental costs for low permeation marine fuel
system hose. Primer bulb costs are presented both for 100 percent FKM and multi-layer
constructions. The incremental cost for the 1/4" fuel lines are presented for the thermoelastic
barrier and the costs for the heavier fuel hose are based on costs of existing nylon barrier marine
hose. These costs include a markup, and no long-term cost savings are applied to these costs
because they are primarily material costs.
Table 6.6-2: Hose Permeation Control Cost Estimates for Typical Marine Vessels
primer bulb
100% FKM
multi-layer
fuel supply/return
fill neck
vent hose
PorTable Tank
6', 1/4" ID fuel hose
primer bulb
$2.13
$1.16
$1.94
-
PWC
5.7', 1/4" ID fuel hose
1.9', 1.5 "ID fill neck
2.0', 1/4" ID vent hose
$1.84
$5.16
$0.65
Installed Tank
9.9', 3/8" ID fuel hose
10. 1', 1.5 "ID fill neck
8.0', 5/8 "ID vent hose
$6.58
$26.12
$10.29
6.6.2 Tank Permeation
PorTable fuel tanks and fuel tanks used in personal watercraft are typically blow-molded
out of FfDPE and have a capacity ranging from 4 to!8 gallons. Because of the manufacturing
process and material used, some permeation control technologies are available that are different
from what would be feasible for larger rotational-molded fuel tanks. Larger, low-production
volume marine fuel tanks are typically rotational-molded out of XLPE. Rotational-molding is
used for smaller production runs because of the much lower relative tooling costs compared to
blow-molding. For fuel tanks in vessels that are subject to the 33 CFR 183 fuel system
requirements, manufacturers have found that fuel tanks molded out of FtDPE will not pass the
fire test, while XLPE fuel tanks will. Therefore, XLPE is used in rotational-molded marine fuel
tanks.
6.6.2.1 Blow-Molded Fuel Tanks
Our surface treatment cost estimates are based on price quotes from companies that
specialize in this fluorination62 and sulfonation.63 The fluorination costs are a function of the
geometry of the fuel tanks because they are based on how many fuel tanks can be fit in a
treatment chamber. The price sheet referenced for fluorination assumes rectangular shaped
containers. For irregular shaped fuel tanks, the costs would be higher because they could not
efficiently utilize the chamber volume. There would be significant void space. We consider a
void space equal to about 25 percent of the volume of the fuel tank. For sulfonation, the shape of
the fuel tanks is less of an issue because the treatment process is limited only by the spacing on
the production line which is roughly the same for the range of fuel tank sizes used for
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Draft Regulatory Impact Analysis
porTable and personal watercraft fuel tanks. These prices do not include the cost of transporting
the tanks; we estimated that shipping, handling and overhead costs would be an additional $0.40-
$1.40 per fuel tank, for tanks ranging from 4-18 gallons.64
As discussed above for Small SI fuel tanks, manufacturers, with high enough production
volumes, could reduce the costs of sulfonating fuel tanks by constructing an in-house treatment
facility. We base our costs for marine fuel tanks on 150,000 tanks per year and use this approach
for our long-term cost determination for sulfonation.
Our estimate of the cost for non-continuous barrier platelets (generally known as Selar) is
based on increased material costs. No changes should be necessary to the blow-molding
equipment. We used 10 percent ethylene vinyl alcohol (EVOH) which is about $3-4 per pound
and 90 percent HDPE which is about $0.65-0.75 per pound.65 This equates to a price increase of
about $0.35 per pound. We then applied the material weights shown in Table 6.5-1 to estimate
costs per tank for this technology.
For higher production volumes, manufacturers may consider blow molding multi-layer
fuel tanks with continuous barriers. Practically, a new blow-molding machine would be required
because four or five additional injection screws would be necessary for the barrier layer, two
adhesion layers, an additional HDPE layer, and potentially a regrind layer. A machine that could
blow-mold multi-layer tanks would approximately double the price of the blow-molding
machine For this analysis, we use a mono-layer machine cost of $1,000,000 and a multi-layer
machine cost of $3,000,000 for smaller tanks and $4,000,000 for larger tanks (>6 gallons)66,
resulting in an increase in machine cost of $2,000,000-$3,000,000. In addition, tooling costs for
each new tank design would be about $50,000. For this analysis we considered a fuel tank with
a material composition of 3 percent EVOH at $3.50/lb, 4 percent adhesive layer at $l/lb, 45
percent regrind, and the remainder HDPE. Our analysis uses a total annual production of
60,000-80,000 blow-molded tanks per year, depending on tank size, with 5 different molds.
Capital costs are amortized over 5 years in the short term and 10 years in the long-term
(reflecting a 10 year life of the machine).
6.6.2.2 Rotational-Molded Fuel Tanks
Most installed fuel tanks are rotational-molded out of XLPE for the reasons discussed
above. As discussed above, barrier treatments have not been demonstrated to provide effective
permeation control for XLPE. In addition, Selar and traditional multi-layer blow-molding
approaches do not work for rotational-molded cross-link polyethylene fuel tanks.
Two approaches were discussed above in the Small SI section for rotational-molded
XLPE fuel tanks: 1) dual-layer molding with a barrier layer and 2) epoxy coating of fuel tanks.
These approaches could also be applied to marine fuel tanks. For the dual layer approach,
marine fuel tank manufacturers have expressed concern that the acetal copolymer will not adhere
well to the XLPE. For large fuel tanks, this could be an issue because the layers could pull apart
and cause leaks at the fittings. As an alternative, one company has developed an approach using
a high grade, non-hygroscopic nylon known a polyamide 11 as a barrier layer. This material
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Costs of Control
costs about $5-7/lb compared to XLPE which costs about $1.20/lb. The barrier layer would
likely be about 20 percent of the total material. Using a nylon cost of $6/lb. and a barrier fraction
of 30 percent, we get an average material cost of $2.64/lb. For the short term, we add a $5,000
cost to the mold or a drop box which we amortize over 100 tanks per year for 5 years.
Consistent with the analysis for Small SI equipment, we do not include the cost of a drop box in
the long term because of the ongoing development of a process that does not require a drop
box.67 In fact, one manufacture is already using a proprietary process to mold multi-layer
rotational-molded fuel tanks without a drop box.
Another material is also available for molding an inner layer in rotomolded XLPE fuel
tanks. This material is poly butylene terephthalate cyclic oligimor and is known by the trade
name CBT®. With this material, no drop box is necessary. The CBT is added in the mold with
the XLPE resin. During the molding process, the XLPE shell forms in the mold. Due to
differences in viscosity and temperature properties, the CBT goes to the inside of the fuel tank.
It then polymerizes to form an inner liner. We use a cost of $5/lb. for CBT in this analysis and
use the same barrier thickness as discussed above.
Another technology that has been demonstrated for reducing permeation from XLPE fuel
tanks is a low permeation epoxy barrier. To apply this barrier, an adhesion treatment must first
be performed to increase the fuel tank surface energy so that the epoxy will adhere to the XLPE.
This can be done through a low level fluorination treatment. For this analysis we use the cost of
level 1 fluorination.68 We use the same void space and shipping costs discussed above for our
fluorination cost analysis. Shipping costs are estimated to range from $4-$ 10 per tank for
20-130 gallon tanks. The epoxy could be applied by dipping the fuel tank or spraying it on like
paint and then the epoxy must be allowed to cure. We include a fixed cost of $10,000 for a
volume of 15,000 fuel tanks per year to account for coating and curing equipment. In addition,
we apply the cost of part of one employee's time (using a labor standard of 15,000 tanks
annually per employee) time to apply the coating and use a labor rate of $28/hr with a 40 percent
markup for overhead which is consistent with our engine costs above. We estimate that the
epoxy cost would be $6-7/lb. Manufacturers have commented that UV-curable epoxy, which
could be processed much faster, would cost $12-15/lb.69'70 We use a cost of $12/lb. for this
analysis. However with only a thin coating needed (we use 0.125 mm), the epoxy layer makes
up only about 2.0-2.5 percent of the material of the fuel tank. Because there are benefits to the
epoxy coating such as allowing the fuel tank to be painted, there may be an incentive to use this
technology even on HOPE fuel tanks. For that reason, we estimated the cost for porTable fuel
tanks as well using the same general assumptions except for a larger production volume of
100,000 tanks per year with a increased labor standard due to the smaller tank sizes.
6.6.2.3 Other Marine Fuel Tank Constructions
We do not anticipate that the permeation standard would affect the cost of metal fuel
tanks. Although some permeation can occur at rubber seals (such as for the sending unit), this
would be small due to the small exposed surface area of the seals.
Another type of fuel tank construction that is used in some applications, such as offshore
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Draft Regulatory Impact Analysis
racing boats, is fiberglass fuel tanks. This fiberglass is commonly made of vinyl ester or epoxy
which have high permeation rates. One manufacturer has developed a fiberglass composite that
uses treated volcanic ash in a carrier matrix to create a non-continuous permeation barrier. This
composite is known as an unsaturated polyester nanocomposite (UPE). In addition to being a
low permeation technology for fiberglass tanks, this construction could also be used as an
alternative for metal or plastic fuel tanks. These low permeation fiberglass constructions can be
fabricated or molded. We estimate that fabricated fiberglass composite fuel tanks would cost at
least as much as metal fuel tanks because of the labor involved in hand constructing the tanks.
However, these fuel tanks may also be molded with an average mold cost of $2,500.71 For the
purposes of this analysis we use a cost increase of 20 percent when comparing this technology to
rotational-molded fuel tanks which is a somewhat lower than the cost of a metal fuel tank.
6.6.2.4 Summary of Fuel Tank Costs per Vessel
Table 6.6-3 summarizes the incremental costs of the fuel tank permeation emission-
control strategies discussed above. For technologies sold by a supplier to the engine
manufacturers, an additional 29 percent markup is included for the supplier's overhead and
profit. Both long-term and short-term costs are presented. The long-term costs account for the
stabilization of the capital investments and the learning curve effect discussed above. We use
the same material, shipping, and fluorination costs for our short-term and long-term estimates
because these cost components are well established with a wide range of applications. As
discussed above, for the multilayer fuel tank constructions, we consider an EVOH barrier for
porTable and PWC fuel tanks and a polyamide 11 barrier for rotational-molded fuel tanks. UPE
fiberglass nanocomposite costs presented here are incremental to rotational-molded XLPE tanks.
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Costs of Control
Table 6.6-3: Tank Permeation Control Cost Estimates for Typical Marine Vessels
fluorination: short term
long term
sulfonation: short term
long term
non-continuous platelets
multi-layer: short term
EVOH long term
multi-layer: short term
PAH long term
multi-layer: CBT
UPE fiberglass short term
nanocomposite long term
epoxy coating: short term
long term
PorTable Tank
6 gallons
$9.30
$7.44
$1.67
$1.26
$1.27
$7.74
$4.22
NA
NA
NA
$5.47
$4.85
PWC
17 gallons
$26
$21
$3.27
$1.29
$3.37
$15
$8.58
NA
NA
NA
$12
$11
Installed Tank
57 gallons
NA
NA
NA
$81
$68
$81
$68
$54
$48
$39
$43
$39
6.6.3 Venting Losses
For porTable fuel tanks, the proposed standards would require the fuel cap to be modified
to remove the user-controlled screw and add a one-way valve. We estimate that the cost of a
vacuum relief valve would be about $0.50 more than the manual valve used on porTable fuel
tanks today. We double this cost to account for upgrading the valve for marine applications. For
personal watercraft, we are not claiming any costs or benefits because these vessels already seal
their fuel tanks with a pressure relief valve.72
Larger fuel tanks are currently vented to atmosphere. One emission-control technology
that could be used to meet our standards would be to seal the fuel tank and use a 1 psi pressure
relief valve to prevent over-pressure. However, manufacturers have commented that their fuel
tanks are not designed to withstand pressure and that the current molding process does not lend
itself to making the fuel tanks more pressure resistant. Their fuel tanks currently deflect
significantly at pressures as low as 1 psi. However, for some fuel tank constructions, a sealed
system may be a viable option. For our cost analysis of this approach, we estimate the cost of a
pressure relief valve to be about $1 based on products available in automotive applications. We
double this cost to account for either upgrading the valve for marine applications or adding a
redundant valve for safety reasons. For this case, we consider in the costs, changes in the fuel
tank design to make it more able to withstand 1 psi of pressure. We estimate that if
manufacturers were to make changes to the geometry of the fuel tank to help withstand 1 psi of
pressure without significant deflection, it could increase the material needed by 10 to 30 percent.
We include a cost estimate of $2,500 for the development of each new mold and amortize it over
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100 tanks per year for 5 years. If the pressure relief valve is placed in the fill-neck cap, no vent
hose would be needed, which would reduce the cost of the fuel system. For the long-term cost
estimate, we consider the cost savings of removing the vent line. For this analysis, based on
conversations with boat builders, we divide the aftermarket hose price73 by four to represent the
cost of the hose to the boat builder.
Diurnal emissions may also be controlled through the use of a carbon canister in the vent
line. The carbon would be purged by air drawn into the fuel tank as the fuel cools. This is
known as passive purge. With a canister system, no significant pressure would build up in the
fuel tank. The canister would be packaged in the existing vent line and a float valve or other
liquid/vapor separation device would be added to the fuel system to ensure that liquid fuel would
not enter the vent line during refueling. We include a cost of $2 for this valve and $0.40 for two
additional hose clamps. In our cost estimates, we consider a canister using marine grade carbon
which is harder and more moisture resistant than typical carbon used in automotive applications.
Data shows that about 2 liters of carbon would be necessary for a 50 gallon fuel tank.74 We
estimate the cost of a canister to vary based on size ranging from about $12 for a 20 gallon tank
to about $38 for a 100 gallon tank.
Pressure could be completely eliminated using a bladder fuel tank because there would
be no vapor space. Based on conversations with a manufacturer of bladder fuel tanks, the
incremental cost of adding a bladder to a fuel tank would increase the fuel tank cost by 30-100
percent, depending on the size and shape of the fuel tank. As with a control strategy using a
pressure relief valve in the fill neck, no vent hose would be needed with a bladder fuel tank.
Pressure in the fuel tank can be minimized by reducing the vapor space in the fuel tank.
A volume compensating air bag can be used to minimize pressure. This air bag would need to be
about 1/4 to 1/3 the volume of the fuel tank. For this analysis we use 1/3 the cost of the bladder
fuel tank to account for the smaller bag size. We also include the cost of a low pressure psi
valve which could be used in conjunction with this technology as a safety backup.
Table 6.6-4: Venting Control Cost Estimates for Typical Marine Vessels
pressure relief valve:
passive purge canister:
bladder fuel tank:
volume compensating
air bag:
short term
long term
short term
long term
short term
long term
short term
long term
PorTable Fuel Tank
6 gallons
$1.29
$1.03
NA
NA
NA
NA
NA
NA
Installed Fuel Tank
57 gallons
$26
$21
$32
$25
$259
$207
$91
$73
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Costs of Control
6.6.4 Certification and Compliance
We anticipate that manufacturers will use design based certification to as an alternative to
emission testing to meet the diurnal emission requirements. However, they will still need to
integrate the emission-control technology into their designs and there will be some engineering
and clerical effort need to submit the required information for certification. We expect that in
the early years, plastic fuel tank manufacturers will perform durability and permeation testing on
their fuel tanks for certification. They will be able to carry over this data in future years and will
be able to carry across this data to other fuel tanks made of similar materials and using the same
permeation control strategy regardless of tank size or shape. Typical certification costs may be
spread between the tank manufacturer, hose manufacturer, and boat builder. For the sake of this
analysis we combine the tank, hose, and boat certification costs to calculate the total certification
of an average fuel system. We estimate that 80 percent of fuel tank sales are plastic and about 25
percent of fuel tanks sold are porTable fuel tanks.
For the first year we estimate fuel tank durability and certification testing to cost about
$15,000 per tank manufacturer on the assumption that the manufacturer will use the same
materials and permeation control strategy for all of their fuel tanks to reduce costs. Low
permeation fuel lines are largely established technology. However, we include a cost of $1,000
to perform certification testing on marine hose. In addition, we estimate about $10,000 for
engineering and clerical work for the tank and hose manufacturers. Boat builder certification
should be a simple letter referencing the tank and hose certificates and design requirements. We
consider a cost of $500 for this effort.
For porTable fuel tank manufacturers we spread these costs over sales of 25,000 tanks
per year. For PWC manufacturers, which are integrated manufacturers, we base the costs on
average annual PWC sales which we estimate to be about 15,000 units per year. For vessels with
installed fuel tanks, the same tank manufacturer will often sell to many boat builders. Therefore,
we base the cost on average sales per tank manufacturer which we estimate to be about 40,000
per year. Although there is currently a limited offering of marine fuel hose products today, we
conservatively use the same lower unit volumes as for fuel tanks when applying hose testing
costs. This represents the scenario where porTable fuel tank manufacturers and PWC
manufacturers perform their own hose testing, while smaller boat builders rely on data from the
hose manufacturers. For non-integrated boat builders using installed fuel tanks, we estimate that
the average sales per year is approximately 250 vessels.
As with other fixed costs, we amortized the cost over 5 years of sales to calculate per unit
certification costs. Combining these costs, we get average fuel system integration and
compliance costs of about $0.22 for porTable fuel tanks, $0.35 for PWC, and $0.53 for fuel
systems on other vessels.
6.6.5 Operating Cost Savings
Evaporative emissions are essentially fuel that is lost to the atmosphere. Over the
lifetime of a marine vessel, this can result in a significant loss of fuel. The proposed reduction in
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Draft Regulatory Impact Analysis
evaporative emissions would therefore result in meaningful fuel savings which can be directly
related to operating cost savings based on an average density of 6 Ibs/gallon for gasoline (based
on lighter hydrocarbons which evaporate first) and the price of gasoline described above.
Table 6.6-5 presents the estimated fuel savings for marine vessels associated with the proposed
evaporative emission standards.
Table 6.6-5: Projected Evaporative Fuel Savings for Marine Vessels
Evaporative HC Reduced [Ibs/life]
Lifetime Gallons Saved
Lifetime Cost Savings
Average Equipment Life [years]
Discounted Cost Savings (7%)
Portable
88
14
$26
12.7
$18
PWC
58
9.4
$17
9.9
$13
Installed
247
41
$74
17
$45
6.6.6 Total Marine Vessel Costs
We expect that marine vessel manufactures will make use of a variety of technologies to
meet the proposed fuel tank permeation and diurnal emission standards. As discussed above,
many options are available so the technologies chosen will depend on the baseline fuel tank
construction, the vessel type, and the manufacturer's particular preferences. The proposed hose
permeation standards will likely be met through the use of barrier hose constructions.
In calculating the costs of this rule, we consider the marine vessel categories in the
NONROAD model. NONROAD divides marine vessels into outboard, personal watercraft, and
SD/I applications and further subdivides these applications into several engine power categories.
This analysis uses the unique hose and tank sizes for each subcategory in the NONROAD model
and described in Chapter 3. For this analysis, we treat all vessels with outboard engines up to 25
hp as having porTable fuel tanks made of plastic. This analysis considers all PWC to have
plastic fuel tanks as well. Based on our understanding of the market share of plastic versus
aluminum tanks, we use a split of 30 percent metal and 70 percent plastic for installed fuel tanks.
We base our cost analysis on likely technologies that manufactures may use. For
porTable and PWC fuel tanks and, we base our tank permeation control costs on multi-layer
coextrusion with an EVOH barrier. For larger installed fuel tanks, we split the costs 50/50
between dual-layer rotational-molded tanks with a nylon barrier and the use of a low-permeation
epoxy coating over the tanks in a post molding process. Diurnal control costs are based on
sealed systems for porTable marine tanks, current technology for PWC, and passive canister
systems for vessels with installed fuel tanks. Fuel supply line costs are based on thermoelastic
barrier technology. No costs or benefits are claimed for vent hose or fill neck hose.
As discussed above, our cost estimates include both variable and fixed costs, and we
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Costs of Control
distinguish between near-term and long-term costs. Because our analysis amortizes fixed costs
over 5 years, the long-term costs are generally made up of variable costs only. The exception to
this is fuel tank permeation control strategies where more expensive molding equipment is used.
We assume an equipment life of 10 years, so in the long term, the amortized additional cost of
the molding equipment is half, on average, of the short-term amortized cost over 5 years (5 years
of amortized payments/10 years of equipment life = l/2). In addition, variable costs are lower in
the long term due to the learning effect discussed in Section 6.1. Table 6.6-6 presents these
average per-engine cost estimates.
Table 6.6-6: Per Vessel Evaporative Emission Cost Estimates (Without Fuel Savings)
PorTable aggregate
tank permeation
hose permeation
diurnal venting
PWC aggregate
tank permeation
hose permeation
diurnal venting
Installed aggregate
tank permeation
hose permeation
diurnal venting
Short Term (years 1-5)
Fixed
$6.65
$6.64
$0.01
$0
$12.95
$12.93
$0.01
$0
$0.63
$0.23
$0.01
$0.40
Variable
$5.39
$1.00
$3.10
$1.29
$4.49
$2.64
$1.84
$0
$73.55
$35.31
$6.54
$31.69
Total
$12.04
$7.65
$3.10
$1.29
$17.43
$15.58
$1.86
$0
$74.18
$35.54
$6.54
$32.09
Long Term (years 6-10)
Fixed
$3.21
$3.21
$0
$0
$6.30
$6.30
$0
$0
$0
$0
$0
$0
Variable
$5.13
$1.00
$3.10
$1.03
$4.49
$2.64
$1.84
$0
$61.53
$29.63
$6.54
$25.35
Total
$8.34
$4.22
$3.10
$1.03
$10.79
$8.94
$1.84
$0
$61.53
$29.63
$6.54
$25.35
6.6.7 Marine Vessel Aggregate Costs
Aggregate costs are calculated by multiplying the per-engine cost estimates described
above by projected vessel sales. Vessel sales are based on estimates from the National Marine
Manufacturers Association (www.nmma.org) and projections for future years are based on the
growth rates in the NONROAD model. A description of the sales and population data and our
analysis of the data are available in the docket.75 Fuel savings are calculated directly from the
projected HC reductions due to the proposed evaporative emission standards. Table 6.6-7
presents the projected costs of the proposed rule over a 30-year time period with and without the
fuel savings associated with reducing evaporative emissions. For the purposes of combining
these costs with the exhaust emission costs described above, we also present the projected costs
by engine type in Table 6.6-8.
The population and sales data reported by NMMA, suggest that the NONROAD model
may somewhat underestimate the useful life of outboard and personal watercraft marine vessels.
If useful life were back-calculated—dividing NMMA population by sales and adjusted for
growth—we would get a longer average life estimate. As a result, the per-vessel fuel savings
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Draft Regulatory Impact Analysis
described above may be understated. Because the current approach gives us a conservative
benefits estimate, and because we do not have new data on average lives for marine vessels to
update the estimates in the NONROAD model, we are not proposing to update the model at this
time. For this reason, the 30-year stream may give a better view of the impact of the fuel savings
than the per-vessel analysis.
At a 7 percent discount rate, over 30 years, the estimated annualized cost to
manufacturers for marine evaporative emission control is $26 million. The estimated
corresponding annualized fuel savings due to control of evaporative emissions from boats is $25
million. At a 3 percent discount rate, the estimated annualized cost to manufacturers for marine
evaporative emission control is $26 million. The estimated corresponding annualized fuel
savings due to control of evaporative emissions from boats is $29 million.
Table 6.6-7: Projected 30-Year Aggregate Cost Stream for Marine Vessels
Year
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
Without Fuel Savings
Portable
$1,964,334
$1,978,506
$1,993,040
$2,007,575
$2,022,109
$907,533
$914,009
$920,405
$926,801
$933,196
$939,592
$945,987
$952,383
$958,779
$965,174
$971,570
$977,966
$984,402
$990,838
$997,274
$1,003,710
$1,010,146
$1,016,582
$1,023,018
$1,029,455
$1,035,891
$1,042,327
$1,048,763
$1,055,199
$1,061,635
PWC
$1,509,992
$1,520,885
$1,532,058
$1,543,230
$1,554,403
$942,509
$949,235
$955,877
$962,520
$969,162
$975,804
$982,446
$989,088
$995,730
$1,002,372
$1,009,014
$1,015,657
$1,022,341
$1,029,025
$1,035,709
$1,042,393
$1,049,077
$1,055,761
$1,062,446
$1,069,130
$1,075,814
$1,082,498
$1,089,182
$1,095,866
$1,102,551
Installed
$2,379,818
$13,357,033
$25,957,390
$26,146,688
$26,335,985
$26,130,013
$24,043,965
$22,304,923
$22,459,914
$22,614,905
$22,769,895
$22,924,886
$23,079,877
$23,234,867
$23,389,858
$23,544,849
$23,699,839
$23,855,811
$24,011,783
$24,167,754
$24,323,726
$24,479,698
$24,635,669
$24,791,641
$24,947,612
$25,103,584
$25,259,556
$25,415,527
$25,571,499
$25,727,471
With Fuel Savings
Portable
$1,696,777
$1,379,654
$1,056,961
$625,447
$227,276
$(1,293,196)
$(1,691,753)
$(2,083,707)
$(2,472,693)
$(2,851,048)
$(3,222,042)
$(3,570,455)
$(3,889,105)
$(4,166,588)
$(4,376,235)
$(4,557,295)
$(4,719,344)
$(4,869,408)
$(5,003,979)
$(5,128,330)
$(5,241,868)
$(5,346,193)
$(5,435,660)
$(5,518,237)
$(5,591,777)
$(5,652,081)
$(5,706,100)
$(5,755,039)
$(5,802,545)
$(5,848,308)
PWC
$1,460,514
$1,416,312
$1,212,780
$1,006,435
$810,625
$(4,533)
$(197,528)
$(384,702)
$(566,360)
$(739,824)
$(887,378)
$(1,018,989)
$(1,095,610)
$(1,152,037)
$(1,197,840)
$(1,236,005)
$(1,268,302)
$(1,295,056)
$(1,316,950)
$(1,334,722)
$(1,348,643)
$(1,359,565)
$(1,368,227)
$(1,376,889)
$(1,385,552)
$(1,394,215)
$(1,402,877)
$(1,411,539)
$(1,420,202)
$(1,428,864)
Installed
$1,930,889
$11,782,975
$23,138,203
$21,066,108
$19,068,161
$16,685,413
$12,428,196
$8,525,783
$6,535,757
$4,561,432
$2,607,303
$667,034
$(1,268,679)
$(3,182,282)
$(5,033,988)
$(6,730,209)
$(8,298,019)
$(9,680,934)
$(10,889,215)
$(11,989,416)
$(12,990,968)
$(13,836,968)
$(14,605,420)
$(15,226,617)
$(15,772,673)
$(16,251,345)
$(16,665,147)
$(17,031,083)
$(17,357,227)
$(17,650,084)
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Costs of Control
Table 6.6-8: Projected 30-Year Aggregate Cost Stream
for Marine Vessels by Engine Type
Year
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
Without Fuel Savings
OB
$4,022,410
$10,590,973
$17,386,587
$17,513,381
$17,640,175
$16,093,724
$14,852,627
$13,701,910
$13,797,121
$13,892,332
$13,987,542
$14,082,753
$14,177,964
$14,273,174
$14,368,385
$14,463,596
$14,558,807
$14,654,620
$14,750,433
$14,846,247
$14,942,060
$15,037,873
$15,133,687
$15,229,500
$15,325,313
$15,421,127
$15,516,940
$15,612,753
$15,708,567
$15,804,380
PWC
$1,509,992
$1,520,885
$1,532,058
$1,543,230
$1,554,403
$942,509
$949,235
$955,877
$962,520
$969,162
$975,804
$982,446
$989,088
$995,730
$1,002,372
$1,009,014
$1,015,657
$1,022,341
$1,029,025
$1,035,709
$1,042,393
$1,049,077
$1,055,761
$1,062,446
$1,069,130
$1,075,814
$1,082,498
$1,089,182
$1,095,866
$1,102,551
SD/I
$321,743
$4,744,565
$10,563,843
$10,640,881
$10,717,919
$10,943,821
$10,105,347
$9,523,418
$9,589,594
$9,655,769
$9,721,945
$9,788,120
$9,854,296
$9,920,472
$9,986,647
$10,052,823
$10,118,998
$10,185,593
$10,252,187
$10,318,782
$10,385,376
$10,451,970
$10,518,565
$10,585,159
$10,651,754
$10,718,348
$10,784,942
$10,851,537
$10,918,131
$10,984,726
With Fuel Savings
OB
$3,335,872
$8,658,576
$14,085,375
$12,010,652
$10,037,991
$6,406,222
$3,082,863
$(139,724)
$(2,098,191)
$(4,033,918)
$(5,946,347)
$(7,826,103)
$(9,665,614)
$(11,445,138)
$(13,099,198)
$(14,574,287)
$(15,910,006)
$(17,057,085)
$(18,024,386)
$(18,887,029)
$(19,667,131)
$(20,343,387)
$(20,957,927)
$(21,506,331)
$(21,999,412)
$(22,427,494)
$(22,797,796)
$(23,125,550)
$(23,420,202)
$(23,687,967)
PWC
$1,460,514
$1,416,312
$1,212,780
$1,006,435
$810,625
$(4,533)
$(197,528)
$(384,702)
$(566,360)
$(739,824)
$(887,378)
$(1,018,989)
$(1,095,610)
$(1,152,037)
$(1,197,840)
$(1,236,005)
$(1,268,302)
$(1,295,056)
$(1,316,950)
$(1,334,722)
$(1,348,643)
$(1,359,565)
$(1,368,227)
$(1,376,889)
$(1,385,552)
$(1,394,215)
$(1,402,877)
$(1,411,539)
$(1,420,202)
$(1,428,864)
SD/I
$291,795
$4,504,054
$10,109,789
$9,680,903
$9,257,446
$8,985,995
$7,653,579
$6,581,800
$6,161,255
$5,744,302
$5,331,609
$4,922,682
$4,507,829
$4,096,269
$3,688,976
$3,286,783
$2,892,643
$2,506,743
$2,131,192
$1,769,284
$1,434,296
$1,160,226
$916,847
$761,478
$634,962
$524,068
$426,549
$339,427
$260,430
$189,575
6.7 Cost Sensitivity Analysis
In developing the cost estimates described above, EPA used data from a wide variety of
sources. These sources included conversations with manufacturers and vendors, published
material costs, government cost tracking, and sales literature. In addition, we discussed many of
our cost estimates with industry experts. Through this process we have received information
suggesting that there is the potential for variability in some of the cost estimates used as inputs to
this analysis. For instance, fuel prices have been rising over the past few years which affects the
dollar value of our fuel savings estimates.
In this section, we perform an analysis of the sensitivity of our cost estimates to the
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Draft Regulatory Impact Analysis
observed variation in costs for several input components of the cost analysis. The input
components that we are focusing on for the sensitivity analysis are those that would be expected
to have a significant effect on the final cost results. These are components that we either
observed high variability when collecting the data, or industry has raised issues about the
uncertainty of the technology which may lead to cost uncertainty.
We are focusing on five elements of the cost analysis for this sensitivity analysis. These
five elements are:
1. gasoline prices
2. precious metal costs
3. fraction of Small SI equipment manufacturers that design their own mufflers
4. electronic fuel injection on all Class II engines with multiple cylinders
5. costs of rotational-molded tank technologies
6.7.1 Gasoline Price Sensitivity
To estimate fuel savings in the above analysis, we used fuel price information obtained
from the U.S. Department of Energy, Energy Information Administration.76 Although 2004 and
2005 gasoline prices are available in published reports, 2006 gasoline prices are not expected to
be reported until mid 2007. However, gasoline price samples throughout the year are available
on-line.77 Based on this information, the national average fuel price, with taxes, from January to
October 2006 was $2.68 per gallon. This price estimate includes both a $0.184/gallon federal
excise tax and approximately a $0.2I/gallon average state excise tax.78 Subtracting these taxes,
we get a fuel cost of $2.29/gallon for 2006.
To investigate the sensitivity of the cost analysis in this chapter to gasoline fuel price, we
looked at the U.S. average fuel prices for 2004 and 2006. These price estimates were calculated
in the same manner as the 2005 estimate. Table 6.7-1 presents these estimates. Fuel savings are
directly related to the gasoline price used in the cost analysis. Therefore, if the 2004 average
gasoline price were used in the cost analysis, the estimated fuel savings would have been about
22 percent lower. If the 2006 price were used, the estimated fuel savings would have been about
27 percent higher. Because of the recent trend of increasing gasoline prices, we may be
understating the fuel savings in our cost analysis. However, using the 2005 fuel price is
consistent with our use of 2005 dollars for the costs in this chapter.
Table 6.7-1 U.S. Average Gasoline Prices [S/Gallon]
Year
2004
2005
2006 (through October)
with taxes
$1.80
$2.20
$2.68
without taxes
$1.41
$1.81
$2.29
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6.7.2 Variation in Precious Metal Prices
Precious metal prices for Platinum and Rhodium have increased over the past 5 years.79
Prices for palladium are currently at their 1998 levels. However, a large spike in palladium
prices was seen in 2000 and 2001. Due to the high variability of this market, we get higher
precious metal cost estimates if we based the price estimates on a recent single month average
(September 2006). If we look at an average over a longer time period (10 years) we calculate
lower platinum costs, but higher rhodium and palladium costs. These precious metal price
estimates are presented in Table 6.7-2.
Table 6.7-2: Precious Metal Prices [per troy oz]
Rhodium
Palladium
Platinum
ICF 3 year Average
$1,121
$210
$811
September 2006
$4,835
$316
$1,134
10 Year Average
$1,356
$341
$623
6.7.2.1 Sensitivity of Small SI Catalyst Costs to Precious Metal Costs
To look at the sensitivity of our cost analysis for Small SI exhaust emission control, we
considered the precious metal cost variability described above. Based on the amount of each of
these precious metals in our projected catalyst designs, Table 6.7-3 presents the impact on per-
engine costs of using the spot price and 10 year average price in our analysis. These costs,
which are broken down by class and useful life, are presented for the near term without fuel
savings.
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Draft Regulatory Impact Analysis
Table 6.7-3: Sensitivity of Small SI Total Per Engine Cost Estimates
to Precious Metal Costs
CLASS
UL
TECH
RULE Cost/Equip
(3 yr avg precious
metal price)
I
125
OHV/SV
14.12
I
250
OHV
19.82
I
500
OHV
26.07
II
250
OHV
46.21
II
500
OHV
50.83
II
1000
OHV
92.17
SEPTEMBER 2006 PRICE
Cost/Equip
Increase
% Increase
$15.69
$1.57
10%
$22.60
$2.78
12%
$30.25
$4.18
14%
$47.48
$1.27
3%
$52.67
$1.84
4%
$96.11
$3.94
4%
10 YEAR AVERAGE
Cost/Equip
Increase
%Increase
$13.91
-$0.21
-1.5%
$19.45
-$0.37
-1.9%
$25.51
-$0.56
-2.2%
45.84
$-0.37
-1%
$51.39
$0.56
1%
$93.80
$1.63
2%
6.7.2.1 Sensitivity of SD/I Catalyst Costs to Precious Metal Costs
To look at the sensitivity of our cost analysis for SD/I exhaust emission control, we
considered the precious metal cost variability described above. Based on the amount of each of
these precious metals in our projected catalyst designs, Table 6.7-4 presents the impact on per-
engine costs of using the spot price and 10 year average price in our analysis. These costs,
which are presented for each of the engine sizes used above for the primary cost analysis, are
near term costs without fuel savings.
Table 6.7-4: Sensitivity of SD/I Cost Estimates to Precious Metal Costs
Primary Analysis
3.0L 14
$483
4.3L V6
$396
5.0L V8
$317
5.7L V8
$300
8.1L V8
$377
Aggregate
$360
September 2006 Precious Metal Prices
Cost
Increase
% Increase
$511
$28
5%
$417
$21
5%
$342
$24
7%
$328
$28
8%
$416
$39
9%
$386
$25
7%
10 Year Average Precious Metal Prices
Cost
Increase
% Increase
$479
-$4
-1%
$393
-$3
-1%
$314
-$4
-1%
$296
-$4
-1%
$371
-$6
-2%
$357
-$4
-1%
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Costs of Control
Catalyst manufacturers usually buy precious metals on contract, not at the market spot
price. Our primary analysis values appear reasonable.
6.7.3 Portion of Equipment Manufacturers Designing Own Muffler System and
Recertifying the Engine
This analysis considers that equipment manufacturers will purchase the muffler design
provided by the engine manufacturer in the engine's certified engine configuration. However,
due to the fact that engine manufacturers will likely not be able to provide catalysts in all of the
muffler designs used by equipment manufacturers, the smaller volume equipment manufacturer
will need to pick their muffler from the limited offerings of the engine manufacturer.
The muffler designs may or may not fit into the equipment produced by the equipment
manufacturer. If it does not, then the equipment manufacturer may choose to utilize the catalyst
brick from their engine manufacturer and work with a muffler manufacturer to redesign their
existing muffler. If they choose this option, then they must undergo expenses to redesign the
muffler and heat shield to apply the catalyst safely. The equipment manufacturer must also pay
for emission test of the new engine/muffler configuration as well as pay the certification fee to
EPA for engine certification.
Applications which may find issues using a predetermined muffler design include those
that have close coupled equipment shrouding or a closed equipment structure. EPA estimates
that 10 percent of equipment companies will find themselves in this situation with at least one
piece of equipment in their product line. Given there are an estimated 413 companies, 41
companies with three differently designed models each yields 123 models. Given that there are
at times more than one engine used in an equipment design, we can assume two engine types per
model - this yields a total of 246 redesigns and certifications. The fixed costs for this work are
listed in Table 6.7-5.
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Draft Regulatory Impact Analysis
Table 6.7-5: Costs for Equipment Manufacturers
to Perform Engine Certification, Class II OHV
Muffler/Heat Shield Design
Emission Test per Certified Engine
Configuration
Estimated EPA Certification Fee
TOTAL Per Equipment Model Per
10% of Equipment Manufacturers =
Engine Type
= 41(x41)
Three equipment models per equipment mfr.
Two engine types per Equipment Model (x2)
TOTAL ESTIMATED COST
Fixed Costs
$75,000
$2012
$800
$77,812
41
123
246
$19,141,752
If this occurred it would add about $19 million dollars to the total compliance cost or
about 0.86 percent of the total 30 year cost net present value.
6.7.4 Electronic Fuel Injection on Class II Engines with Multiple Cylinders
The current proposal states that only a portion of an engine manufacturers Class II engine
families of two or more cylinders per engine will incorporate electronic fuel injection. In the
event that success with the technology results in all Class II engines of two or more cylinders
using the technology, then the cost stream of this rulemaking will change. Table 6.7-6 compares
the estimated costs of catalysts and fuel injection.
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Costs of Control
Table 6.7-6: Cost Comparison Between Catalyst and EFI
Technology
Class II V-twin
250
500
1000
Variable Costs
V-Twin Catalyst
Electronic Fuel
Injection
Difference
$49.59
$78.99
$28.40
$53.47
$78.99
$25.52
$62.32
$78.99
$16.67
Fixed Costs
V-Twin Catalyst
Electronic Fuel
Injection
Difference
$364,133
$103,020
-$261,113
$364,133
$103,020
-$261,113
$364,133
$103,020
-$261,113
The resultant change in cost/equipment for this is shown in Table 6.7-7. The costs
presented here are for the near term and long term without fuel savings. The reason that costs do
not change very much overall is due to the fact that there is still a significant portion of Class II
engines that are single cylinder whose costs estimates are not changing.
Table 6.7-7
Sales Weighted Average Cost Per Class II Equipment
250
500
1000
Short Term (first year - includes fixed cost)
Proposal
All Class II V-Twin to EFI
Difference
$46.21
$46.80
$0.59
1.3%
$50.83
$49.71
-$1.12
2.2%
$92.17
$91.55
-$0.62
0.67%
Long Term (6th year and beyond)
Proposal
All Class II V-Twin to EFI
Difference
$32.56
$33.16
$0.60
1.8%
$27.13
$27.15
$0.02
0.07%
$49.80
$50.62
$0.82
1.6%
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Draft Regulatory Impact Analysis
The estimated fuel savings for a residential riding mower is $39.00 net present value over
its lifetime. EFI is estimated to cost $79.00 after consideration of the savings from removal of
the existing carburetor. Therefore, the increase in the overall hardware cost with fuel savings is
$40.00.
6.7.5 Costs of Rotational-Molded Tank Technologies
Many of the fuel tank permeation control technologies discussed in Chapter 5 are used
widely today. One exception is multi-layer rotationally-molded fuel tanks. One tank
manufacturer is currently producing fuel tanks for Small SI equipment with a nylon inner layer.
This manufacturer has stated that they are able to produce these fuel tanks using the normal
molding process without additional equipment. However, other manufacturers who sell tanks
into Small SI and marine applications have expressed concern that they do not know how to
mold tanks with nylon inner liners without the use of a drop box. As described above, a drop
box is an added component on a mold that opens during the molding process to add a second
layer of material into the mold. These manufacturers have indicated that they are working with
another material, CBT (discussed above and in Chapter 5), that would not require a drop box.
However, they have not finished their evaluation of this technology. Marine fuel tank
manufacturers have expressed the concern that if the cost of plastic fuel tanks were too high, that
more boat builders may begin using aluminum fuel tanks.
To examine the uncertainty in what technologies will be used to reduce permeation from
rotationally molded fuel tanks, we considered three factors listed below. As with the analysis
above, we present costs for typical fuel tank sizes rather than trying to present every fuel tank
size considered in the cost model. The two fuel tank sizes used here are a 5 gallon tank for
Small SI equipment and a 57 gallon fuel tank for boats.
1. Cost of using a drop box in the rotational-molding process
2. Sensitivity to variations in material costs
3. Consideration of replacing plastic with metal fuel tanks in marine industry
In the analysis described above, we include a $5,000 cost per mold in the near term to
account for the cost using drop boxes. This cost was based on a range of cost estimates supplied
by tank manufacturers ranging from $1,000 to nearly $9,000 per mold for adding drop boxes. In
the long term we projected that tank manufacturers would all be able to mold fuel tanks without
the use of a drop box. This projection was based on the current practices of one manufacturer
and on alternative processes that other manufacturers are investigating today. To look at the
sensitivity of tank permeation control costs for rotationally-molded fuel tanks, we consider costs
without drop boxes and with $9,000 drop boxes.
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Costs of Control
Table 6.7-8: Sensitivity of Rotomolded Tank Cost Estimates to Drop Box Cost
Primary Analysis ($5,000 drop box)
5 Gallon Small SI Tank
$5.54
57 Gallon Boat Tank
$81
Without Drop Box
Cost
Increase
% Increase
With $9,000 Drop Box
Cost
Increase
% Increase
$4.25
($1.29)
-23%
$6.58
1.04
19%
$68
($13)
-16%
$92
$10
13%
The analysis above considers three multi-layer approaches to rotationally-molded fuel
tanks. These approaches are molding with a nylon inner layer using a drop box, molding with a
slightly more expensive CBT layer without a drop box, and a post processing epoxy coating. All
three of these approaches would be sensitive to changes in barrier material prices. Because these
are new materials for fuel tank applications, it would be possible that material costs would
decrease over time with increased production volumes. At the same time, increases in material
costs could occur, especially for materials with prices tied closely to petroleum prices (such as
polyethylene). To consider the sensitivity of fuel tank cost to material costs, we consider the fuel
tank construction with a nylon barrier. Here we consider both a 20 percent decrease and a 20
percent increase in material costs, both for the nylon and the cross-link polyethylene. This
translates a cross-link polyethylene cost ranging from $0.96 to $1.44/lb. and nylon costs ranging
from to a nylon cost ranging from $3.20 to $4.80/lb. for Small SI and $4.8 to $7.2/lb. for marine
fuel tanks.
Table 6.7-9: Sensitivity of Rotomolded Tank Cost Estimates to Material Cost
Primary Analysis
5 Gallon Small SI Tank
$5.54
57 Gallon Boat Tank
$81
20% Decrease in Material Costs
Cost
Increase
% Increase
$5.18
($0.85)
-15%
$68
($14)
-17%
20% Increase in Material Costs
Cost
Increase
% Increase
$6.40
$0.86
15%
$95
($14)
17%
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Draft Regulatory Impact Analysis
Marine fuel tanks that are installed in marine vessels are primarily rotationally-molded
out of cross-link polyethylene. However, many fuel tank are also made of aluminum. Very
large fuel tanks (typically greater in size than rotationally-molded fuel tanks) are often made out
of fiberglass. Marine fuel tank manufacturers making rotationally-molded fuel tanks have
expressed the concern that if the costs were to increase too high, that many boat builders would
switch to using aluminum fuel tanks. Based on conversations with industry, plastic fuel tanks
sell for about 2/3 to 3/4 the price of aluminum fuel tanks.
One manufacturer of multi-layer rotationally-molded fuel tanks with a nylon inner layer
has stated that they sell these fuel tanks at a price about 50 percent higher than traditional mono-
layer fuel tanks. Although this puts the plastic tanks into the price range of metal fuel tanks,
there are other downstream costs that would also need to be considered. Boat builders have
indicated that it is common for aluminum fuel tanks to corrode when exposed to water. For this
reason, they typically include a large access panel to the fuel tank when metal fuel tanks are
used. The use of an access panel greatly reduces the cost of replacing a fuel tank if necessary.
This access panel adds cost and complexity to the boat and may affect where the fuel tank can be
positioned in the boat. Boat manufacturers have indicated that, when plastic fuel tanks are used,
the only access required is to the hose connections on one end of the fuel tank.
In addition to the cost of an access panel for removing corroded tanks, the cost of
replacing the fuel tank must be considered. This would essentially double the price of the metal
tank, even without considering labor costs. In addition, fuel spills could create other damage in
the boat or even a safety hazard. Repeated problems with fuel tank corrosion could hurt the
reputation of the boat builder and leave them open to litigation. For these reasons, many boat
builders that have already chosen to use plastic fuel tanks would be expected to continue to use
these fuel tanks, even if they were roughly the same cost as metal fuel tanks.
We analyzed at two effects that could have an impact on our estimate of the price of low
permeation plastic fuel tanks. It seems unlikely that a high cost drop box would be necessary
given that one manufacturer is already producing multi-layer tanks without using a drop box. In
addition, the CBT technology is designed to not require the use of a drop box. While material
costs may fluctuate, it is not likely that a 20 percent increase in nylon would be observed. The
volume of this material sold is large and this rule would not be expected to limit availability of
the material. In addition, manufacturers have indicated that nylon prices have not risen greatly
with increased petroleum costs. Even with a 20 percent material price increase it seems unlikely
that boat builders would switch to using metal tanks. Manufacturers using plastic tanks have
indicated that they do so more for durability advantages with respect to corrosion than for a price
savings. In addition, the life time cost savings of plastic fuel tanks would outweigh the material
price increase. These lifetime cost savings include the installation of access ports to allow
replacement of the tanks, actual replacement of corroded tanks, and customer perception of poor
quality if tanks were to corrode.
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Costs of Control
Chapter 6 References
1. "Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
2. "Update of EPA's Motor Vehicle Emission Control Equipment Retail Price Equivalent (RPE) Calculation
Formula," Jack Faucett Associates, Report No. JACKFAU-85-322-3, September 1985, Docket Identification EPA-
HQ-OAR-2004-0008-0204.
3. For further information on learning curves, see Chapter 5 of the Economic Impact, from "Regulatory Impact
Analysis—Control if Air Pollution from New Motor Vehicles: Tier 2 Motor Vehicle Emissions Standards and
Gasoline Sulfur Control Requirements," U.S. EPA, December 1999, EPA420-R-99-023. A copy of this document is
included in Air Docket A-2000-01, at Document No. II-A-83. The interested reader should also refer to previous
final rules for Tier 2 highway vehicles (65 FR 6698, February 10, 2000), marine diesel engines (64 FR 73300,
December 29, 1999), nonroad diesel engines (63 FR 56968, October 23, 1998), and highway diesel engines (62 FR
54694, October 21, 1997).
4. "Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
5."Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
6. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
7. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
8. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
9."Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
10."Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
11. "Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
12. "Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
13. "Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
6-101
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Draft Regulatory Impact Analysis
14. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
15. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
16. "Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
17."Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
18."Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
19."Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
20."Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
21. "Small SI Engine Technologies and Costs, Draft Report" ICF International, prepared for U.S. Environmental
Protection Agency, August 2006, Docket Identification EPA-HQ-OAR-2004-008-0253.
22. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
23. "Small SI Engine Technologies and Costs, Draft Report," ICF International, August 2006, Docket Identification
EPA-HQ-OAR-2004-008-0253.
24. "Small SI Engine Technologies and Costs, Draft Report," ICF International, August 2006, Docket Identification
EPA-HQ-OAR-2004-008-0253.
25. "Summary of 2002 Nonhandheld Equipment Market by Manufacturer Size", EPA Memo by Phil Carlson to
Docket EPA_HQ_OAR_2004_0008_0542.
26. "Build it, and they will come," OEM Off-Highway, page 74-78, November 1996.
27. "EFI Hits the Small Engine Market," Diesel Progress, pages 52-54, July 1998.
28. Memorandum from Alex Rogozhin, RTI, to Chi Li, U.S. EPA, "Calculation of Motor Gasoline Prices in Small SI
Rule EIA," November 10, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0449.
29. Memorandum from Alex Rogozhin, RTI, to Chi Li, U.S. EPA, "Calculation of Motor Gasoline Prices in Small SI
Rule EIA," November 10, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0449.
30. "Marine Outboard and Personal Watercraft SI Engine Technologies and Costs," ICF Consulting, prepared for
the U.S. Environmental Protection Agency, July 2006, Docket Identification EPA-HQ-OAR-2004-0008-0452.
31. Memorandum from Alex Rogozhin, RTI, to Chi Li, U. S. EPA, "Calculation of Motor Gasoline Prices in Small SI
Rule EIA," November 10, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0449.
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Costs of Control
32. "Updates to Technology Mix, Emissions Factors, Deterioration Rates, Power Distribution, and Fuel
Consumption Estimates for SI Marine Engines in the NONROAD Emissions Inventory Model," Memorandum from
Mike Samulski, U.S. EPA to Docket, November 30, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0361.
33. "Updates to Technology Mix, Emissions Factors, Deterioration Rates, Power Distribution, and Fuel
Consumption Estimates for SI Marine Engines in the NONROAD Emissions Inventory Model," Memorandum from
Mike Samulski, U.S. EPA to Docket, November 30, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0361.
34. Samulski, M., "Marine SI Sales and Price Estimates," U.S. EPA, August 30, 2004, Docket Identification EPA-
HQ-OAR-2004-0008-0448.
35. "Sterndrive and Inboard Marine SI Engine Technologies and Costs," ICF Consulting, prepared for the U.S.
Environmental Protection Agency, July 2006, Docket Identification EPA-HQ-OAR-2004-0008-0453.
36. "Updates to Technology Mix, Emissions Factors, Deterioration Rates, Power Distribution, and Fuel
Consumption Estimates for SI Marine Engines in the NONROAD Emissions Inventory Model," Memorandum from
Mike Samulski, U.S. EPA to Docket, November 30, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0361.
37. Samulski, M., "Marine SI Sales and Price Estimates," U.S. EPA, August 30, 2004, Docket Identification EPA-
HQ-OAR-2004-0008-0448.
38. Trident Marine Hose, "Retail Price List 2001," Docket Identification EPA-HQ-OAR-2004-0008-0226.
39. Denbow, R., Browning, L., Coleman, D., "Report Submitted for WA 2-9, Evaluation of the Costs and
Capabilities of Vehicle Evaporative Emission Control Technologies," ICF, ARCADIS Geraghty & Miller, March
22, 1999, Docket Identification EPA-HQ-OAR-2004-0008-0194.
40. "Meeting with Avon on June 27, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-01,
August 6, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0207.
41. "Information on Costs and Effectiveness of Fluorination Received from Fluoroseal," Memorandum from Mike
Samulski to Docket A-2000-1, March 27, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0201.
42. "Visit to Sulfo Technologies LLC on April 18, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket
A-2000-01, April 22, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0232.
43. "Shipping Costs," Memorandum from Glenn Passavant, U.S. EPA to Docket A-2000-01, March 27, 2002,
Docket Identification EPA-HQ-OAR-2004-0008-0222.
44. "Visit to Sulfo Technologies LLC on April 18, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket
A-2000-01, April 22, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0232.
45. "Plastic News," Resin Pricing for November 8, 2004, www.plasticnews.com, Docket Identification EPA-HQ-
OAR-2004-0008-0442.
46. Ward, Geoff, "Potential Small Entity Representative (SER) Response to Initial Outreach Document: Exhaust
and Evaporative Emissions Control from Small SI Engines and Equipment and Marine SI Engines and Vessels,"
Agri-Industrial Plastics, July 25, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0427.
47. "Plastic News," Resin Pricing for November 8, 2004, www.plasticnews.com, Docket Identification EPA-HQ-
OAR-2004-0008-0442.
48. "Visit to Kracor, Inc.," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-02, March 31, 2003,
Docket Identification EPA-HQ-OAR-2004-0008-0249.
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49. Written comments from Robert Porter, Inca Molded Products to Phil Carlson, U.S.EPA regarding impacts of
regulation on small business, July 24, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0426.
50. Written comments from Jim Harden, Grady-White Boats to Phil Carlson, U.S.EPA regarding impacts of
regulation on small business, July 25, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0437.
51. "Petro-Seal for Ultra-Low Fuel Permeation," Ron Partridge, Arkema Inc., Presentation at the International Boat
Exposition, October 25, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0252.
52. "Plastic News," Resin Pricing for November 8, 2004, www.plasticnews.com, Docket Identification EPA-HQ-
OAR-2004-0008-0442.
53. "Information on Costs and Effectiveness of Fluorination Received from Fluoroseal," Memorandum from Mike
Samulski to Docket A-2000-1, March 27, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0201.
54. Written comments from Robert Porter, Inca Molded Products to Phil Carlson, U.S.EPA regarding impacts of
regulation on small business, July 24, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0426.
55. Written comments from Jim Harden, Grady-White Boats to Phil Carlson, U.S.EPA regarding impacts of
regulation on small business, July 25, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0437.
56. "Comments by Brunswick Corporation; Notice of Proposed Rulemaking; Part 1045 Control of Emissions from
Spark-Ignition Marine Vessels," Rolf Lichtner, Mercury Marine, January 7, 2003, Docket Identification EPA-HQ-
OAR-2004-0008-0192.
57. Trident Rubber Inc., "Trident Marine Hose, Retail Price List 2001," Docket Identification EPA-HQ-
OAR-2004-0008-0226.
58. Denbow, R., Browning, L., Coleman, D., "Report Submitted for WA 2-9, Evaluation of the Costs and
Capabilities of Vehicle Evaporative Emission Control Technologies," ICF, ARCADIS Geraghty & Miller, March
22, 1999, Docket Identification EPA-HQ-OAR-2004-0008-0194.
59. "Meeting with Avon on June 27, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-01,
August 6, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0207.
60. Lawrence Marine; NovaFlex Group, "Industrial Price List: Marine Products," October 15, 2004, Docket
IdentificationEPA-HQ-OAR-2004-0008-0439.
61. Trident Rubber Inc., "Trident Marine Hose, Retail Price List, October 2005," Docket Identification EPA-HQ-
OAR-2004-0008-0444.
62. "Information on Costs and Effectiveness of Fluorination Received from Fluoroseal," Memorandum from Mike
Samulski to Docket A-2000-1, March 27, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0201.
63. "Visit to Sulfo Technologies LLC on April 18, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket
A-2000-01, April 22, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0232.
64. "Shipping Costs," Memorandum from Glenn Passavant, U.S. EPA to Docket A-2000-01, March 27, 2002,
Docket Identification EPA-HQ-OAR-2004-0008-0222.
65. "Plastic News," Resin Pricing for November 8, 2004, www.plasticnews.com, Docket Identification EPA-HQ-
OAR-2004-0008-0442.
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66. Ward, Geoff, "Potential Small Entity Representative (SER) Response to Initial Outreach Document: Exhaust
and Evaporative Emissions Control from Small SI Engines and Equipment and Marine SI Engines and Vessels,"
Agri-Industrial Plastics, July 25, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0427.
67. "Petro-Seal for Ultra-Low Fuel Permeation," Ron Partridge, Arkema Inc., Presentation at the International Boat
Exposition, October 25, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0252.
68. "Information on Costs and Effectiveness of Fluorination Received from Fluoroseal," Memorandum from Mike
Samulski to Docket A-2000-1, March 27, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0201.
69. Written comments from Robert Porter, Inca Molded Products to Phil Carlson, U.S.EPA regarding impacts of
regulation on small business, July 24, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0426.
70. Written comments from Jim Harden, Grady-White Boats to Phil Carlson, U.S.EPA regarding impacts of
regulation on small business, July 25, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0437.
71. "Marine Fuel Containment; A Permanent Solution," Jason Chambers, Engineered Composite Structures Inc.,
Presentation at the 2004 International Boat Exposition, October 25, 2004, Docket Identification EPA-HQ-
OAR-2004-0008-0247.
72. Meetings with NMMA on Marine Emission Standards," Memorandum from Mike Samulski, U.S. EPA to
Docket A-2000-02, March 4, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0250.
73. Trident Marine Hose, "Retail Price List 2001," Docket Identification EPA-HQ-OAR-2004-0008-0226.
74. "Activated Carbon for Use in Marine Evaporative Control Applications," MeadWestvaco Corporation,
Presentation at the International Boat Exposition, October 25, 2004, Docket Identification EPA-HQ-
OAR-2004-0008-0248.
75. Samulski, M., "Marine SI Sales and Price Estimates," U.S. EPA, August 30, 2004, Docket Identification EPA-
HQ-OAR-2004-0008-0448.
76. Memorandum from Alex Rogozhin, RTI, to Chi Li, U.S. EPA, "Calculation of Motor Gasoline Prices in Small SI
Rule EIA," November 10, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0449.
77. Energy Information Administration, "Retail Gasoline Historical Prices," downloaded from
http://www.eia.doe.gov/oil_gas/petroleum/data_publications/wrgp/mogas_history.html, on October 25, 2006, Docket
Identifications? A-HQ-OAR-2004-0008-0450.
78. Federal Highway Administration, "Tax Rates on Motor Fuel - 2003," downloaded from
http://www.eia.doe.gov/oil_gas/petroleum/data_publications/wrgp/gasoline_taxes.html on October 25, 2006, Docket
Identification EPA-HQ-OAR-2004-0008-0451.
79. Johnson Matthey, "Platinum Today," www.platinum.matthey.com, downloaded October 25, 2006, Docket
IdentificationEPA-HQ-OAR-2004-0008-0422.
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Cost Per Ton
CHAPTER 7: Cost Per Ton
This Chapter will present the cost effectiveness analysis we completed for our proposed
small spark ignition engine (<19 kW) and recreational marine (personal water craft,
sterndrive/inboard and outboard) emission standards. Under Clean Air Act section 213, we are
required to promulgate standards which reflect the greatest degree of emission reduction
achievable, giving appropriate consideration to cost, energy, and safety factors. The standards
setting process is not necessarily premised on setting the most cost effective standards, even
though this is a significant factor. Cost-effectiveness is a useful tool in evaluating the
appropriateness of our standards.
The cost-effectiveness analysis described in this chapter relies in part on cost information
from Chapter 6 and emissions information from Chapter 3 to estimate the dollars per ton of
emission reductions produced from our proposed standards. We have calculated the cost
effectiveness using a 30-year net present value approach that accounts for all costs and emission
reductions over a 30-year period. Finally, this chapter compares the cost effectiveness of the
new provisions with the cost effectiveness of other control strategies from previous and potential
future EPA programs.
Section 7.1 describes the calculation behind the 30 year net present value cost
effectiveness and Section 7.2 lists the results of the calculations for our combined small spark
ignition standards (exhaust and evaporative) and marine engines (exhaust and evaporative).
Table 7.2-.5 lists the results for the 30-year net present value cost effectiveness analysis for
Small SI and Marine. The results of the cost-effectiveness of comparative programs are listed in
Table 7.2-6.
7.1 30-Year Net Present Value Cost Effectiveness (Cost per Ton)
We have calculated the cost effectiveness of our program using a "30-year net present
value" approach that includes all nationwide emission reductions and costs for a 30 year period.
This timeframe captures both the early period of the program when only the new
equipment/engines meeting our standards will be in the fleet, and the later period when
essentially all vehicles/engines in the fleet will meet our standards. The 30-year net present
value approach does have one important drawback in that it includes the engine costs for engines
sold 30 years after the program goes into effect, but includes almost none of the emission
benefits from those engines. Thus the 30-year net present value approach does not necessarily
match all costs with all the emission reductions that those costs are intended to produce. It is
presented here, nevertheless, as a reasonable means by which to assess the cost effectiveness of
these programs.
We have calculated this "30-year net present value" cost-effectiveness using the net
present value of the annual emission reductions and costs described in Chapters 3 and 6,
respectively. The calculation of 30-year net present value cost-effectiveness follows the pattern
described above for the per-engine analysis:
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Draft Regulatory Impact Analysis
DNAE =
Where:
DNAE = Reduction in nationwide 30-year net present value emissions in tons
= Reduction in nationwide emissions in tons for year i of the program
= Year of the program, counting from year 1 to year 30
and
i-2008
Where:
DNAC = Nationwide 30-year net present value costs in dollars
(NC); = Nationwide costs in dollars for year i of the program
i = Year of the program from year 1 to year 30
The 30-year net present value cost-effectiveness is produced by dividing DNAC by DNAE. The
nationwide reductions in emissions for each year are given in Chapter 3. The results are given in
Tables within the following section.
7.2 Results
We calculated the cost-effectiveness of our program on a 30-year net present value basis
separately for our proposed Small SI standards <19kW and recreational marine standards. To do
this, we summed net present value of total costs from Chapter 6, and divided by the sum of the
net present value of tons reduced from Chapter 3. These costs and emission reductions are
repeated in Appendices 7-A and 7-B. The results are given in Table 7.2-1 to 7.2-2 for Small SI
engines and equipment and 7.2-3 and 7.2-4 for recreational marine engines and vessels.
Table 7.2-1: 30-year Net Present Value Cost-effectiveness of the Standards
for Small SI Engines <19kW Without Fuel Savings (7 percent discount rate)
Pollutants
HC+NOx
Exhaust
Evaporative
Exhaust + Evap
NPV Costs
(million $)
$3,315
$829
$4,144
NPVReduction
(tons)
1,785,000
1,074,000
2,860,000
Cost per Ton
$1860
$770
$1450
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Cost Per Ton
Table 7.2-2: 30-year Net Present Value Cost-effectiveness of the Standards
for Small SI Engines <19kW With Fuel Savings (7 percent discount rate)
Pollutants
HC+NOx
Exhaust
Evaporative
Exhaust + Evap
NPV Costs
(million $)
$2,539
$186
$2,725
NPVReduction
(tons)
1,785,000
1,074,000
2,860,000
Cost per Ton
$1420
$170
$950
Table 7.2-3: 30-year Net Present Value Cost-effectiveness of the Standards
for Marine Engines Without Fuel Savings (7 percent discount rate)
Pollutants
HC+NOx
Exhaust
Evaporative
Exhaust + Evap
NPV Costs
(million $)
$1,748
$324
$2,071
NPVReduction
(tons)
2,140,000
510,000
2,650,000
Cost per Ton
$820
$630
$780
Table 7.2-4: 30-year Net Present Value Cost-effectiveness of the Standards
for Marine Engines With Fuel Savings (7 percent discount rate)
Pollutants
HC+NOx
Exhaust
Evaporative
Exhaust + Evap
NPV Costs
(million $)
$917
$18
$934
NPVReduction
(tons)
2,140,000
510,000
2,650,000
Cost per Ton
$430
$35
$350
Because many of the benefits and costs are manifest in future years, we apply
discounting methods to adjust the dollar values of these effects to reflect the finding that society
as a whole typically values the realization (or avoidance) of a given effect differently depending
on when the effect occurs. In the discounting calculations used to produce the net present values
that were used in our cost-effectiveness calculations, we used a discount rate of 7 percent,
consistent with the 7 percent rate reflected in the cost-effectiveness analyses for other recent
mobile source programs. OMB Circular A-94 requires us to generate benefit and cost estimates
reflecting a 7 percent rate.
However, the cost and cost-effectiveness estimates for future proposed mobile source
programs could also reflect a 3 percent discount rate. The 3 percent rate is in the 2 to 3 percent
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Draft Regulatory Impact Analysis
range recommended by the Science Advisory Board's Environmental Economics Advisory
Committee for use in EPA social benefit-cost analyses, a recommendation incorporated in EPA's
new Guidelines for Preparing Economic Analyses (November 2000). Therefore, we have also
calculated the overall cost-effectiveness of today's rule based on a 3 percent rate to facilitate
comparison of the cost-effectiveness of this rule with future proposed rules which use the 3
percent rate. The results are shown in Tables 7.2-5 through 7.2-8.
Table 7.2-5: 30-year Net Present Value Cost-effectiveness of the Standards
for Small SI Engines <19kW Without Fuel Savings (3 percent discount rate)
Pollutants
HC+NOx
Exhaust
Evaporative
Exhaust + Evap
NPV Costs
(million $)
$5,502
$1,367
$6,869
NPVReduction
(tons)
3,228,000
1,893,000
5,121,000
Cost per Ton
$1,700
$720
$1,340
Table 7.2-6: 30-year Net Present Value Cost-effectiveness of the Standards
for Small SI Engines <19kW With Fuel Savings (3 percent discount rate)
Pollutants
HC+NOx
Exhaust
Evaporative
Exhaust + Evap
NPV Costs
(million $)
$4,109
$234
$4,342
NPVReduction
(tons)
3,228,000
1,893,000
5,121,000
Cost per Ton
$1,270
$120
$850
Table 7.2-7: 30-year Net Present Value Cost-effectiveness of the Standards
for Marine Engines Without Fuel Savings (3 percent discount rate)
Pollutants
HC+NOx
Exhaust
Evaporative
Exhaust + Evap
NPV Costs
(million $)
$2,632
$505
$3,137
NPVReduction
(tons)
3,824,000
954,000
4,778,000
Cost per Ton
$690
$530
$660
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Cost Per Ton
Table 7.2-8: 30-year Net Present Value Cost-effectiveness of the Standards
for Marine Engines With Fuel Savings (3 percent discount rate)
Pollutants
HC+NOx
Exhaust
Evaporative
Exhaust + Evap
NPV Costs
(million $)
$1,145
($66)
$1,079
NPVReduction
(tons)
3,824,000
954,000
4,778,000
Cost per Ton
$300
($70)
$230
Because one primary purpose of cost-effectiveness is to compare our program to
alternative programs, we listed the cost effectiveness of several previous EPA actions for
controlled emissions from mobile sources for NOx and NMHC in Table 7.2-9. The programs
shown in these tables are those for which cost-effectiveness was calculated in a similar manner
allowing for a comparison. (Note: costs adjusted to 2005 dollars.)
Table 7.2-9: Cost-effectiveness of
Recent Mobile Source Exhaust Emission Programs for HC+NOx, 2005$
(7 percent discount with fuel savings)
Program
2002 HH engines Phase 2
2001 NHH Engines Phase 2
1998 Marine SI engines
2004 Comm Marine CI
2007 Large SI exhaust
2006 ATV exhaust
2006 off-highway motorcycle
2006 recreational marine CI
2010 snowmobile
2006 <50cc highway motorcycle
2010 Class 3 highway motorcycle
$/ton
840
neg*
1900
200
80
300
290
700
1430
1860
1650
* fuel savings outweigh engineering/hardware costs
Costs adjusted to 2005$ using http://wwwl.jsc.msa.gov/bu2/inflateGDP.html
Permeation and other evaporative emission control measures we have implemented for
highway and off-highway motorcycles, large SI engines, ATVs, and snowmobiles have all had
cost effectiveness values of less than $0/ton due to the fuel savings.
The analyses supporting the values in Table 7.2-6 were conducted over the past ten years
and thus not all were done on a purely identical basis in terms of their analytical approach (e.g.,
factors such as cost streams and cost recovery). By comparing values in Table 7.2-6 for
NOx+HC to those presented above we can see that the cost-effectiveness of our proposed Small
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Draft Regulatory Impact Analysis
SI and recreational Marine SI standards fall within the range of these other programs. Some
previous programs have been more cost effective (lower $/ton) than the program we are
proposing today. However, it should be expected that the next generation of standards will be
more expensive than the last, because earlier reductions are usually easier and less expensive to
achieve and the least costly means for reducing emissions is generally pursued first.
This proposed rule also will bring environmental benefits related to reductions in carbon
monoxide (CO) emissions and emissions of direct particulate matter (PM). We have elected to
base our cost effectiveness analysis solely on HC+NOx for two reasons. First, with regard to
PM and CO, no new or additional technology beyond that needed to achieve the proposed
HC+NOx standards is expected to be required. These reductions will occur as part of the
technology and related efforts to meet the HC+NOx standards. Second, in the case of PM, we
are not setting standards but do expect reductions to occur as a result of engine changes and in
some cases the use of aftertreatment. In neither case is significant additional effort needed.
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Cost-Benefit Analysis
CHAPTER 8: Cost-Benefit Analysis
8.1 Overview
Mobile sources are significant contributors to air pollutant emissions across the country
and into the future. The Agency has determined that these emissions cause or contribute to air
pollution which may reasonably be anticipated to endanger public health or welfare, and is
therefore establishing standards to control these emissions. The health- and environmentally-
related effects associated with these emissions are a classic example of an externality-related
market failure. An externality occurs when one party's actions impose uncompensated costs on
another party. The proposed Small SI and Marine SI engine standards will help correct this
market failure.
EPA is required by Executive Order (E.O.) 12866 to estimate the benefits and costs of
major new pollution control regulations. Accordingly, the analysis presented here attempts to
answer three questions: (1) what are the physical health and welfare effects of changes in
ambient air quality resulting from particulate matter (PM) and ozone precursor emission
reductions (direct PM, NOX and VOC)? (2) what is the monetary value of the changes in these
effects attributable to the proposed rule? and (3) how do the monetized benefits compare to the
costs? It constitutes one part of EPA's thorough examination of the relative merits of this
regulation.
This chapter presents our analysis of the health and environmental benefits that can be
expected to occur as a result of the proposed standards throughout the period from initial
implementation through 2030. Nationwide, the engines subject to the proposed emission
standards in this rule are a significant source of mobile source air pollution. The proposed
standards would reduce exposure to VOC, direct PM2.5, NOx and CO emissions and help avoid a
range of adverse health effects associated with ambient ozone and PM2.s levels. In addition, the
proposed standards would help reduce exposure to CO, air toxics, and PM2.5 for persons who
operate or who work with or are otherwise active in close proximity to these engines.
The analysis presented in this chapter uses a methodology generally consistent with
benefits analyses performed for the recent analysis of the the Clean Air Nonroad Diesel Rule
(CAND) and the Mobile Source Air Toxics Rule (MSAT).u To the extent possible, we also
incorporate benefits analysis methods consistent with the approach used in the recent RIA for the
PM NAAQS.3 For this reason, the current chapter avoids repeating this information and refers to
the appropriate sections of each RIA. The benefits analysis relies on two major components:
1) Calculation of the impact of the proposed standards on the national direct PM and NOx
emissions inventories for two future years (2020 and 2030).
2) A benefits analysis to determine the changes in human health, both in terms of physical
effects and monetary value, based on a PM benefits transfer approach that scales CAND
results (see Section 8.2).
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Draft Regulatory Impact Analysis
It should be noted that since the CAND rule, EPA's Office of Air and Radiation (OAR) has
adopted a different format for its benefits analysis in which characterization of uncertainty is
integrated into the main benefits analysis. The benefits scaling approach used in the analysis of
the proposed standards limits our ability to integrate uncertainty into the main analysis. For the
benefits analysis of the final standards, we will adopt this integrated uncertainty approach.
Please see the PM NAAQS RIA for an indication of the uncertainty present in the base estimate
of benefits and the sensitivity of our results to the use of alternative concentration-response
functions.
A wide range of human health and welfare effects are linked to the emissions of VOCs,
direct PM and NOx and the resulting impact on ambient concentrations of ozone and PM2.5.
Recent studies have linked short-term ozone exposures with premature mortality. Exposure to
ozone has also been linked to a variety of respiratory effects including hospital admissions and
illnesses resulting in school absences. Potential human health effects associated with PM2.5
range from premature mortality to morbidity effects linked to long-term (chronic) and shorter-
term (acute) exposures (e.g., respiratory and cardiovascular symptoms resulting in hospital
admissions, asthma exacerbations, and acute and chronic bronchitis). Welfare effects potentially
linked to PM include materials damage and visibility impacts, while ozone can adversely affect
the agricultural and forestry sectors by decreasing yields of crops and forests.
EPA typically quantifies PM- and ozone-related benefits in its regulatory impact analyses
(RIAs) when possible. In the analysis of past air quality regulations, ozone-related benefits have
included morbidity endpoints and welfare effects such as damage to commercial crops. EPA has
not recently included a separate and additive mortality effect for ozone, independent of the effect
associated with fine particulate matter. For a number of reasons, including 1) advice from the
Science Advisory Board (SAB) Health and Ecological Effects Subcommittee (HEES) that EPA
consider the plausibility and viability of including an estimate of premature mortality associated
with short-term ozone exposure in its benefits analyses and 2) conclusions regarding the
scientific support for such relationships in EPA's 2006 Air Quality Criteria for Ozone and
Related Photochemical Oxidants (the CD), EPA is in the process of determining how to
appropriately characterize ozone-related mortality benefits within the context of benefits
analyses for air quality regulations. As part of this process, we are seeking advice from the
National Academy of Sciences (NAS) regarding how the ozone-mortality literature should be
used to quantify the reduction in premature mortality due to diminished exposure to ozone, the
amount of life expectancy to be added and the monetary value of this increased life expectancy
in the context of health benefits analyses associated with regulatory assessments. In addition, the
Agency has sought advice on characterizing and communicating the uncertainty associated with
each of these aspects in health benefit analyses.
Since the NAS effort is not expected to conclude until 2008, the agency is currently
deliberating how best to characterize ozone-related mortality benefits in its rulemaking analyses
in the interim. For the analysis of the proposed locomotive and marine standards, we do not
quantify an ozone mortality benefit. So that we do not provide an incomplete picture of all of the
benefits associated with reductions in emissions of ozone precursors, we have chosen not to
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Cost-Benefit Analysis
include an estimate of total ozone benefits in the proposed RIA. By omitting ozone benefits in
this proposal, we acknowledge that this analysis underestimates the benefits associated with the
proposed standards. Our analysis, however, indicates that the rule's monetized PM2 5 benefits
alone substantially exceed our estimate of the costs.
Table 8.1-1 summarizes the annual monetized health and welfare benefits associated with
the proposed standards for two years, 2020 and 2030. The PM2 5 benefits are scaled based on
relative changes in direct PM and NOx emissions between this rule and the proposed Clean Air
Nonroad Diesel (CAND) rule.A As explained in Section 8.2.1 of this chapter, the PM25 benefits
scaling approach is limited to those studies, health impacts, and assumptions that were used in
the proposed CAND analysis. As a result, PM-related premature mortality is based on the
updated analysis of the American Cancer Society cohort (ACS; Pope et al., 2002). However, it is
important to note that since the CAND rule, EPA's Office of Air and Radiation (OAR) has
adopted a different format for its benefits analysis in which characterization of the uncertainty in
the concentration-response function is integrated into the main benefits analysis. Within this
context, additional data sources are available, including a recent expert elicitation and updated
analysis of the Six-Cities Study cohort (Laden et al., 2006). Please see the PM NAAQS RIA for
an indication of the sensitivity of our results to use of alternative concentration-response
functions.
The analysis presented here assumes a PM threshold of 3 ug/m3, equivalent to
background. Through the RIA for CAIR, EPA's consistent approach had been to model
premature mortality associated with PM exposure as a nonthreshold effect; that is, with harmful
effects to exposed populations modeled regardless of the absolute level of ambient PM
concentrations. This approach had been supported by advice from EPA's technical peer review
panel, the Science Advisory Board's Health Effects Subcommittee (SAB-HES). However,
EPA's most recent PM2.5 Criteria Document concludes that "the available evidence does not
either support or refute the existence of thresholds for the effects of PM on mortality across the
range of concentrations in the studies," (p. 9-44).4 Furthermore, in the RIA for the PM NAAQS
we used a threshold of 10 ug/m3 based on recommendations by CAS AC for the Staff Paper
analysis. We consider the impact of a potential, assumed threshold in the PM-mortality
concentration response function in Section 8.6.2.2 of the RIA.
A Due to time and resource constraints, EPA scaled the final CAND benefits estimates from the benefits estimated
for the CAND proposal. The scaling approach used in that analysis, and applied here, is described in the RIA for the
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final CAND rule.2
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Draft Regulatory Impact Analysis
Table 8.1-1. Estimated Monetized PM-Related Health Benefits of the Proposed Standards
Using a 3% discount rate
Using a 7% discount rate
Total Benefits3' b'c (billions 2003$)
2020
$2.1 + B
S1.9 + B
2030
$3.4 + B
$3.1 + B
Benefits include avoided cases of mortality, chronic illness, and other morbidity health endpoints. PM-related
mortality benefits estimated using an assumed PM threshold at background levels (3 ug/m3). There is
uncertainty about which assumed threshold to use and this may impact the magnitude of the total benefits
estimate. For a more detailed discussion of this issue, please refer to Section 8.6.2.2 of the PJA.
For notational purposes, unqualified benefits are indicated with a "B" to represent the sum of additional
monetary benefits and disbenefits. A detailed listing of unqualified health and welfare effects is provided in
Table 8.1-2 of the RIA.
Results reflect the use of two different discount rates: 3 and 7 percent, which are recommended by EPA's
Guidelines for Preparing Economic Analyses5 and OMB Circular A-4.6 Results are rounded to two significant
digits for ease of presentation and computation.
Table 8.1-2 lists the full complement of human health and welfare effects associated with
PM, ozone and air toxics, and identifies those effects that are quantified for the primary estimate
and those that remain unquantified because of current limitations in methods or available data.
Table 8.1-2. Human Health and Welfare Effects of Pollutants Affected by the Proposed
Standards
Pollutant/Effect
Quantified and Monetized in Base
Estimates"
Unquantified Effects - Changes in:
PM/Healthb
Premature mortality based on cohort
study estimates0
Bronchitis: chronic and acute
Hospital admissions: respiratory
and cardiovascular
Emergency room visits for asthma
Nonfatal heart attacks (myocardial
infarction)
Lower and upper respiratory illness
Minor restricted-activity days
Work loss days
Asthma exacerbations (asthmatic
population)
Respiratory symptoms (asthmatic
population)
Infant mortality
Premature mortality: short-term exposures'1
Subchronic bronchitis cases
Low birth weight
Pulmonary function
Chronic respiratory diseases other than chronic bronchitis
Nonasthma respiratory emergency room visits
UVb exposure (+/-)e
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Cost-Benefit Analysis
Pollutant/Effect
Quantified and Monetized in Base
Estimates"
Unquantified Effects - Changes in:
PM/Welfare
Visibility in Southeastern Class I areas
Visibility in northeastern and Midwestern Class I areas
Household soiling
Visibility in we stern U.S. Class I areas
Visibility in residential and non-Class I areas
UVb exposure (+/-)e
Ozone/Healthf
Premature mortality: short-term exposures8
Hospital admissions: respiratory
Emergency room visits for asthma
Minor restricted-activity days
School loss days
Asthma attacks
Cardiovascular emergency room visits
Acute respiratory symptoms
Chronic respiratory damage
Premature aging of the lungs
Nonasthma respiratory emergency room visits
UVb exposure (+/-)e
Ozone/Welfare
Decreased outdoor worker productivity
Yields for:
- Commercial forests
- Fruits and vegetables, and
- Other commercial and noncommercial crops
Damage to urban ornamental plants
Recreational demand from damaged forest aesthetics
Ecosystem functions
UVb exposure (+/-)e
MSAT Health11
Cancer (benzene, 1,3-butadiene, formaldehyde,
acetaldehyde, naphthalene)
Anemia (benzene)
Disruption of production of blood components (benzene)
Reduction in the number of blood platelets (benzene)
Excessive bone marrow formation (benzene)
Depression of lymphocyte counts (benzene)
Reproductive and developmental effects (1,3-butadiene)
Irritation of eyes and mucus membranes (formaldehyde)
Respiratory irritation (formaldehyde)
Asthma attacks in asthmatics (formaldehyde)
Asthma-like symptoms in non-asthmatics (formaldehyde)
Irritation of the eyes, skin, and respiratory tract
(acetaldehyde)
Upper respiratory tract irritation and congestion (acrolein)
Neurotoxicity (n-hexane, toluene, xylenes)
MSAT Welfare11
Direct toxic effects to animals
Bioaccumulation in the food chain
Damage to ecosystem function
Odor
a Primary quantified and monetized effects are those included when determining the primary estimate of total
monetized benefits of the proposed standards.
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Draft Regulatory Impact Analysis
b In addition to primary economic endpoints, there are a number of biological responses that have been associated
with PM health effects including morphological changes and altered host defense mechanisms. The public health
impact of these biological responses may be partly represented by our quantified endpoints.
0 Cohort estimates are designed to examine the effects of long term exposures to ambient pollution, but relative risk
estimates may also incorporate some effects due to shorter-term exposures (see Kunzli, 2001 for a discussion of this
issue).7
d While some of the effects of short-term exposure are likely to be captured by the cohort estimates, there may be
additional premature mortality from short-term PM exposure not captured in the cohort estimates included in the
primary analysis.
e May result in benefits or disbenefits. See Section 8.5.3. for more details.
f In addition to primary economic endpoints, there are a number of biological responses that have been associated
with ozone health including increased airway responsiveness to stimuli, inflammation in the lung, acute
inflammation and respiratory cell damage, and increased susceptibility to respiratory infection. The public health
impact of these biological responses may be partly represented by our quantified endpoints.
gEPA sponsored a series of meta-analyses of the ozone mortality epidemiology literature, published in the July 2005
volume of the journal Epidemiology, which found that short-term exposures to ozone may have a significant effect
on daily mortality rates, independent of exposure to PM. EPA is currently considering how to include an estimate of
ozone mortality in its benefits analyses.
h The categorization of unqualified toxic health and welfare effects is not exhaustive.
Figure 8.1-1 illustrates the major steps in the PM benefits analysis. Given the change in
direct PM and NOx emissions modeled for the proposed standards, we use a benefits transfer
approach to scale PM benefits estimated for the CAND analysis (see Section 8.2 for a description
of the scaling approach). For the CAND analysis, EPA ran a sophisticated photochemical air
quality model, the Regional Modeling System for Aerosols and Deposition (REMSAD), to
estimate baseline and post-control ambient concentrations of PM for each future year (2020 and
2030). The estimated changes in ambient concentrations were then combined with population
projections to estimate population-level potential exposures to changes in ambient
concentrations. Changes in population exposure to ambient air pollution were then input to
impact functions8 to generate changes in the incidence of health effects. The resulting changes
in incidence were then assigned monetary values, taking into account adjustments to values for
growth in real income out to the year of analysis (values for health and welfare effects are in
general positively related to real income levels). Values for individual health and welfare effects
were summed to obtain an estimate of the total monetary value of the changes in emissions.
Finally, we scale the CAND results to reflect the magnitude of the direct PM and NOx emissions
changes we estimate will occur as a result of the proposed standards.
Benefits estimates calculated for the CAND analysis, and scaled for the proposed
B The term "impact function" as used here refers to the combination of a) an effect estimate obtained from the
epidemiological literature, b) the baseline incidence estimate for the health effect of interest in the modeled
population, c) the size of that modeled population, and d) the change in the ambient air pollution metric of interest.
These elements are combined in the impact function to generate estimates of changes in incidence of the health
effect. The impact function is distinct from the C-R function, which strictly refers to the estimated equation from
the epidemiological study relating incidence of the health effect and ambient pollution. We refer to the specific
value of the relative risk or estimated coefficients in the epidemiological study as the "effect estimate." In
referencing the functions used to generate changes in incidence of health effects for this RIA, we use the term
"impact function" rather than C-R function because "impact function" includes all key input parameters used in the
incidence calculation.
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Cost-Benefit Analysis
standards, were generated using the Environmental Benefits Mapping and Analysis Program
(BenMAP). BenMAP is a computer program developed by EPA that integrates a number of the
modeling elements used in previous RIA's (e.g., interpolation functions, population projections,
health impact functions, valuation functions, analysis and pooling methods) to translate modeled
air concentration estimates into health effect incidence estimates and monetized benefit
estimates. Interested parties may wish to consult the webpage
http://www.epa.gov/ttn/ecas/benmodels.html for more information.
Figure 8.1-1. Key Steps in Air Quality Modeling Based Benefits Analysis
INPUTS
Emissions inventories
(CAND)
Air quality monitoring data
C oncentration re sp o
functions
ise
PROCESSES
INPUTS
Mo del CAND baseline and
post-control ambient PM2j
(REMSAD)
Interpolation of projected air
concentration surfaces (base and
control)
BenMAP
integrated
model
Model population exposure to
changes in ambient concentrations
Estimate expected changes in
human health outcomes
Estimate monetary value of
changes in human health
Adjust monetary values for growth
in real income to year of analysis
Sum health and welfare monetary
values to obtain total monetary
benefits
All of the benefit estimates for the proposed control options in this analysis are based on
an analytical structure and sequence similar to that used in the benefits analyses for the CAND
final rule, the CAIR rule, and, when feasible, the final PM NAAQS analysis.0 By adopting the
major design elements, models, and assumptions developed in recent RIAs, we rely on methods
that have already received extensive review by the independent Science Advisory Board (SAB),
c See: Clean Air Nonroad Diesel final rule (69 FR 38958, June 29, 2004); Clean Air Interstate final rule (70 FR
25162, May 12, 2005); PM NAAQS (71 FR61144, Oct. 17, 2006).
8-7
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Draft Regulatory Impact Analysis
by the public, and by other federal agencies. In addition, we will be working through the next
section 812 prospective study to enhance our methods.0
This chapter is organized as follows. In Section 8.2, we provide an overview of the air
quality impacts modeled for the proposed standards that are used as inputs to the benefits
analysis. In Section 8.3, we document key differences between this benefits analysis and the
benefits analysis completed for the final CAIR and CAND rules. This section also presents and
discusses the key inputs and methods used in the benefits analysis. In Section 8.4, we report the
results of the analysis for human health and welfare effects. Section 8.5 qualitatively describes
benefits categories that are omitted from this analysis, due either to inadequate methods or
resources. Section 8.6 discusses how we incorporate uncertainty into our analysis. Section 8.7
discusses the health-based cost-effectiveness analysis for the proposed standards. Finally, in
Section 8.8, we present a comparison of the costs and benefits associated with the proposed
standards.
8.2 Air Quality Impacts
This section summarizes the methods for and results of estimating air quality for the 2020
and 2030 base case and proposed control scenario for the purposes of the benefits analysis. EPA
has focused on the health, welfare, and ecological effects that have been linked to ambient
changes in PM2.5 related to direct PM and NOx emission reductions estimated to occur due to the
proposed standards. We do this by scaling the modeled relationship between emissions and
ambient PM concentrations observed for the CAND analysis.8
8.2.1 PM Air Quality Impact Estimation
To estimate PM2.5 benefits from the proposed standards, we rely on a benefits transfer
technique. The benefits transfer approach uses as its foundation the relationship between
emission reductions and ambient PM2.5 concentrations modeled for the Clean Air Nonroad Diesel
(CAND) proposal.E For a given future year, we first calculate the ratio between CAND PM2.5
precursor emission reductions (direct PM and NOx) and PM2.5 precursor emission reductions
associated with the proposed standards (proposed emission reductions/CAND emission
reductions, displayed in Table 8.2-1). We multiply these ratios by the percent that each PM2.5
precursor contributes towards population-weighted reductions in total PM2 5 due to the CAND
standards (displayed in Table 8.2-2). This calculation results in a "benefits apportionment
factor" for the relationship between direct PM emissions and ambient PM2 5 and NOx emissions
and ambient PM2 5 (displayed in Table 8.2-3). The benefits apportionment factors are then
applied to the BenMAP-based incidence and monetized benefits from the CAND proposal. In
this way, we apportion the results of the proposed CAND analysis to its underlying PM2.5
precursor emission reductions and scale the apportioned benefits to reflect differences in
D Interested parties may want to consult the webpage: http://www.epa.gov/sciencel regarding components of the
812 prospective analytical blueprint.
E See 68 FR 28327, May 23, 2003.
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Cost-Benefit Analysis
emission reductions between the two rules. This benefits transfer method is consistent with the
approach used in other recent mobile and stationary source rules.0 We refer the reader to the
final CAND RIA for more details on this benefits transfer approach.9
Table 8.2-1. Comparison of 48-state Emission Reductions in 2020 and 2030 Between the
CAND Rule and Proposed Standards
Emissions Species
2020
NOx
Direct PM2 5
2030
NOx
Direct PM2 5
Reduction from Baseline (tons)
CAND Modeling
Inputs3
663,618
98,121
1,009,774
138,208
Small Si/Marine SI
Emissions
Changes13
72,257
4,896
98,146
6,299
Ratio of Reductions
(Proposal/ CAND)
0.11
0.05
0.10
0.05
a Includes all affected nonroad sources: land-based, recreational marine, commercial
marine, and locomotives. See the CAND RIA for more information regarding the
CAND emission inventories.
b Includes changes to the small spark ignition engine inventory (lawn and garden
equipment) and recreational marine spark ignition engine inventory.
Note that while the proposed regulations also control VOCs, which contribute to PM formation, the benefits
transfer scaling approach only scales benefits based on NOx, SO2, and direct PM emission reductions. PM benefits
will likely be underestimated as a result, though we are unable to estimate the magnitude of the underestimation.
G See: Clean Air Nonroad Diesel final rule (69 FR 38958, June 29, 2004); Nonroad Large Spark-Ignition Engines
and Recreational Engines standards (67 FR 68241, November 8, 2002); Final Industrial Boilers and Process Heaters
NESHAP (69 FR 55217, September 13, 2004); Final Reciprocating Internal Combustion Engines NESHAP (69 FR
33473, June 15, 2004); Final Clean Air Visibility Rule (EPA-452/R-05-004, June 15, 2005); Ozone Implementation
Rule (70 FR 71611, November 29, 2005).
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Draft Regulatory Impact Analysis
Table 8.2-2. Apportionment of Modeled CAND Preliminary Control Option Population-
weighted Change in Ambient PM2.s to Nitrate, Sulfate, and Primary Particles
Total PM2 5
Sulfate
Nitrate
Primary PM
2020
Population-weighted
Change (ug/m3)
Percent of Total
Change
0.316
0.071
0.041
0.203
22.5%
13.1%
64.4%
2030
Population-weighted
Change (ug/m3)
Percent of Total
Change
0.438
0.090
0.073
0.274
20.5%
16.8%
62.7%
Source: CAND RIA, Chapter 9.
Table 8.2-3. Calculation of PM2.s Benefits Apportionment Factors for the Proposed
Emission Reductions
NOx
Emissions
Direct PM
Emissions
2020
Ratio of
Emission
Reductions3
(1)
0.11
0.05
% of Total
Ambient
Changeb
(2)
0.131
0.644
Benefits
Apportionment
Factor
(1*2)
0.014
0.032
2030
Ratio of
Emission
Reductions3
(3)
0.10
0.05
% of Total
Ambient
Changeb
(4)
0.168
0.627
Benefits
Apportionment
Factor
(3*4)
0.016
0.029
3 Calculated by dividing the small SI and marine SI engine emission reductions by CAND emission reductions. See
Table 8.2-1.
b See Table 8.2-2.
8.3 PM-Related Health Benefits Estimation - Methods and Inputs
The analytical approach used in this benefits analysis is largely the same approach used
in the Final CAND benefits analysis and the reader is referred to that RIA for details on the
benefits methods and inputs. This analysis, however, also reflects some advances in data and
methods in epidemiology, economics, and health impact estimation consistent with the approach
used in the recent RIA for the PM NAAQS. Updates to the assumptions and methods used in
estimating PM2.s-related benefits since the analysis for the CAND rule include the following:
Consistent with the approach used in the recent RIA for the PM NAAQS, we have
updated our projections of mortality incidence rates to be consistent with the U.S.
Census population projections that form the basis of our future population estimates.
Compared to the methodology used in the CAIR analysis, this change will result in a
reduction in mortality impacts in future years, as overall mortality rates are projected
to decline for most age groups. A memorandum drafted by Abt Associates (Abt
Associates, 2005) contains complete details regarding the derivation of mortality rate
8-10
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Cost-Benefit Analysis
adjustment factors, and estimation of future-year mortality rates used in the
10
analysis. The scaled mortality benefits for the proposed standards have been
updated accordingly.
• Consistent with the approach used in the recent RIA for the PM NAAQS, we use a
revised mortality lag assumption. In the Final CAND, we used a five-year segmented
lag. Since that analysis, upon which the PM benefits transfer scaling approach is
based, the SAB Health Effects Subcommittee (HES) recommended that until
additional research has been completed, EPA should assume a segmented lag
structure characterized by 30 percent of mortality reductions occurring in the first
year, 50 percent occurring evenly over years 2 to 5 after the reduction in PM2.5, and
20 percent occurring evenly over the years 6 to 20 after the reduction in PM2 5. The
distribution of deaths over the latency period is intended to reflect the contribution of
short-term exposures in the first year, cardiopulmonary deaths in the 2- to 5-year
period, and long-term lung disease and lung cancer in the 6- to 20-year period. For
future analyses, the specific distribution of deaths over time will need to be
determined through research on causes of death and progression of diseases
associated with air pollution. It is important to keep in mind that changes in the lag
assumptions do not change the total number of estimated deaths but rather the timing
of those deaths. This approach is different than the 5-year segmented lag used in the
CAND analysis, and the scaled benefits analysis of the proposed standards has been
updated accordingly.
For the purposes of this RIA, the health impacts analysis is limited to those health effects
that are directly linked to ambient levels of air pollution and specifically to those linked to PM.
The specific studies from which effect estimates for the primary analysis are drawn are included
in Table 8.3-1. The specific unit values used for economic valuation of health endpoints are
included in Table 8.3-2.
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Draft Regulatory Impact Analysis
Table 8.3-1. Endpoints and Studies Used to Calculate Total Monetized Health Benefits"
Endpoint
Pollutant
Study
Study
Population
Premature Mortality
Premature mortality
— ACS cohort study,
all-cause
Premature mortality
— all-cause
PM25
PM25
Pope etal. (2002) n
Woodruff etal. (1997)12
>29 years
Infant (<1 year)
Chronic Illness
Chronic bronchitis
Nonfatal heart attacks
PM25
PM25
Abbey etal. (1995)13
Peters etal. (200 1)14
>26 years
Adults
Hospital Admissions
Respiratory
Cardiovascular
Asthma-related ER
visits
PM25
PM25
PM25
PM25
PM25
PM25
PM25
Pooled estimate:
Moolgavkar (2003)15— ICD 490-496 (COPD)
Ito (2003) 16— ICD 490-496 (COPD)
Moolgavkar (2000) 17— ICD 490-496 (COPD)
Ito (2003)— ICD 480-486 (pneumonia)
Sheppard (2003)18— ICD 493 (asthma)
Pooled estimate:
Moolgavkar (2003)— ICD 390-429 (all cardiovascular)
Ito (2003)— ICD 410-414, 427-428 (ischemic heart
disease, dysrhythmia, heart failure)
Moolgavkar (2000)— ICD 390-429 (all cardiovascular)
Norrisetal. (1999)19
>64 years
20-64 years
>64 years
<65 years
>64 years
20-64 years
0-18 years
Other Health Endpoints
Acute bronchitis
Upper respiratory
symptoms
Lower respiratory
symptoms
Asthma
exacerbations
Work loss days
MRADs
PM25
PM25
PM25
PM25
PM25
PM25
Dockeryetal. (1996)20
Pope etal. (1991)21
Schwartz and Neas (2000) 22
Pooled estimate:
Ostro et al. (200 1)23 (cough, wheeze and shortness of
breath)
Vedal et al. (1998)24 (cough)
Ostro (1987)25
Ostro and Rothschild (1989)26
8-12 years
Asthmatics, 9-
1 1 years
7-14 years
6-18yearsb
18-65 years
18-65 years
a The endpoints and studies used for the primary estimate of benefits associated with the proposed rule have been
subject to external technical guidance and review, including the Health Effects Subgroup (HES) of the EPA's
Science Advisory Board (SAB) and the Office of Management and Budget (OMB).
b The original study populations were 8 to 13 for the Ostro et al. (2001) study and 6 to 13 for the Vedal et al.
(1998) study. Based on advice from the SAB-HES, we extended the applied population to 6 to 18, reflecting the
common biological basis for the effect in children in the broader age group.
8-12
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Table 8.3-2. Unit Values Used for Economic Valuation of Health Endpoints (2000$)a
Health Endpoint
Premature Mortality (Value of a
Statistical Life)
Chronic Bronchitis (CB)
Nonfatal Myocardial Infarction
(heart attack)
3% discount rate
Age 0-24
Age 25^4
Age 45-54
Age 55-65
Age 66 and over
7% discount rate
Age 0-24
Age 25^4
AopdS S4
Age 55-65
Age 66 and over
Central Estimate of Value Per Statistical Incidence
1990 Income
Level
$5,500,000
$340,000
$66,902
$74,676
$78,834
$140,649
$66,902
$65,293
$73,149
$76,871
$132,214
$65,293
2020 Income
Level"
$6,600,000
$420,000
$66,902
$74,676
$78,834
$140,649
$66,902
$65,293
$73,149
$76,871
$132,214
$65,293
2030 Income
Level"
$6,800,000
$430,000
$66,902
$74,676
$78,834
$140,649
$66,902
$65,293
$73,149
$76,871
$132,214
$65,293
Derivation of Estimates
Point estimate is the mean of a normal distribution with a 95 percent
confidence interval between $1 and $10 million. Confidence interval is
based on two meta-analyses of the wage-risk VSL literature: $1 million
represents the lower end of the interquartile range from the Mrozek and
Taylor (2002)27 meta-analysis and $10 million represents the upper end of
the interquartile range from the Viscusi and Aldy (2003)28 meta-analysis.
The VSL represents the value of a small change in mortality risk aggregated
over the affected population.
Point estimate is the mean of a generated distribution of WTP to avoid a case
of pollution-related CB. WTP to avoid a case of pollution-related CB is
derived by adjusting WTP (as described in Viscusi et al., [1991]29) to avoid
a severe case of CB for the difference in severity and taking into account the
elasticity of WTP with respect to severity of CB.
Age-specific cost-of-illness values reflect lost earnings and direct medical
costs over a 5-year period following a nonfatal MI. Lost earnings estimates
are based on Cropper and Krupnick (1990). 30 Direct medical costs are based
on simple average of estimates from Russell et al. (1998)31 and Wittels et al.
(1990). 32
Lost earnings:
Cropper and Krupnick ( 1 990). Present discounted value of 5 years of lost
earnings:
age of onset: at 3% at 7%
25-44 $8,774 $7,855
45-54 $12,932 $11,578
55-65 $74,746 $66,920
Direct medical expenses: An average of:
1. Wittels et al. (1990) ($102,658— no discounting)
2. Russell et al. (1998), 5-year period ($22,331 at 3% discount rate; $21,1 13
at 7% discount rate)
(continued)
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Table 8.3-2. Unit Values Used for Economic Valuation of Health Endpoints (2000$)a (continued)
Health Endpoint
Central Estimate of Value Per Statistical
Incidence
1990 Income
Level
2020 Income
Level"
2030 Income
Level"
Derivation of Estimates
Hospital Admissions
Chronic Obstructive Pulmonary
Disease (COPD)
(ICD codes 490-492, 494-496)
Pneumonia
(ICD codes 480-487)
Asthma Admissions
All Cardiovascular
(ICD codes 390-429)
Emergency Room Visits for Asthma
$12,378
$14,693
$6,634
$18,387
$286
$12,378
$14,693
$6,634
$18,387
$286
$12,378
$14,693
$6,634
$18,387
$286
The COI estimates (lost earnings plus direct medical costs) are based on
ICD-9 code-level information (e.g., average hospital care costs, average
length of hospital stay, and weighted share of total COPD category illnesses)
reported in Agency for Healthcare Research and Quality (2000)33
(www.ahrq.gov).
The COI estimates (lost earnings plus direct medical costs) are based on
ICD-9 code-level information (e.g., average hospital care costs, average
length of hospital stay, and weighted share of total pneumonia category
illnesses) reported in Agency for Healthcare Research and Quality (2000)
(www.ahrq.gov).
The COI estimates (lost earnings plus direct medical costs) are based on
ICD-9 code-level information (e.g., average hospital care costs, average
length of hospital stay, and weighted share of total asthma category illnesses)
reported in Agency for Healthcare Research and Quality (2000)
(www.ahrq.gov).
The COI estimates (lost earnings plus direct medical costs) are based on
ICD-9 code-level information (e.g., average hospital care costs, average
length of hospital stay, and weighted share of total cardiovascular category
illnesses) reported in Agency for Healthcare Research and Quality (2000)
(www.ahrq.gov).
Simple average of two unit COI values:
(1) $311.55, from Smith etal. (1997)34 and
(2) $260.67, from Stanford et al. (1999). 35
(continued)
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Table 8.3-2. Unit Values Used for Economic Valuation of Health Endpoints (2000$)a (continued)
Health Endpoint
Central Estimate of Value Per Statistical
Incidence
1990 Income
Level
2020 Income
Level"
2030 Income
Level"
Derivation of Estimates
Respiratory Ailments Not Requiring Hospitalization
Upper Respiratory Symptoms (URS)
Lower Respiratory Symptoms (LRS)
Asthma Exacerbations
Acute Bronchitis
$25
$16
$42
$360
$27
$17
$45
$380
$27
$17
$45
$390
Combinations of the three symptoms for which WTP estimates are available
that closely match those listed by Pope et al. result in seven different
"symptom clusters," each describing a "type" of URS. A dollar value was
derived for each type of URS, using mid-range estimates of WTP (lEc,
1994)36 to avoid each symptom in the cluster and assuming additivity of
WTPs. The dollar value for URS is the average of the dollar values for the
seven different types of URS.
Combinations of the four symptoms for which WTP estimates are available
that closely match those listed by Schwartz et al. result in 1 1 different
"symptom clusters," each describing a "type" of LRS. A dollar value was
derived for each type of LRS, using mid-range estimates of WTP (lEc, 1994)
to avoid each symptom in the cluster and assuming additivity of WTPs. The
dollar value for LRS is the average of the dollar values for the 1 1 different
types of LRS.
Asthma exacerbations are valued at $42 per incidence, based on the mean of
average WTP estimates for the four severity definitions of a "bad asthma
day," described in Rowe and Chestnut (1986). 37 This study surveyed
asthmatics to estimate WTP for avoidance of a "bad asthma day," as defined
by the subjects. For purposes of valuation, an asthma attack is assumed to be
equivalent to a day in which asthma is moderate or worse as reported in the
Rowe and Chestnut (1986) study.
Assumes a 6-day episode, with daily value equal to the average of low and
high values for related respiratory symptoms recommended in Neumann et
al. (1994).38
(continued)
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Table 8.3-2. Unit Values Used for Economic Valuation of Health Endpoints (2000$)a (continued)
Health Endpoint
Central Estimate of Value Per Statistical Incidence
1990 Income
Level
2020 Income
Level"
2030 Income
Level"
Derivation of Estimates
Restricted Activity and Work/School Loss Days
Work Loss Days (WLDs)
Minor Restricted Activity Days
(MRADs)
Variable
(national
median = )
$51
$54
$55
County-specific median annual wages divided by 50 (assuming 2 weeks of
vacation) and then by 5 — to get median daily wage. U.S. Year 2000
Census, compiled by Geolytics, Inc.
Median WTP estimate to avoid one MRAD from Tolley et al. (1986).J9
a Although the unit values presented in this table are in year 2000 dollars, all monetized annual benefit estimates associated with the proposed standards have been inflated to
reflect values in year 2005 dollars. We use the Consumer Price Indexes to adjust both WTP- and COI-based benefits estimates to 2005 dollars from 2000 dollars.40 For WTP-
based estimates, we use an inflation factor of 1.13 based on the CPI-U for "all items." For COI-based estimates, we use an inflation factor of 1.24 based on the CPI-U for medical
care.
Our analysis accounts for expected growth in real income over time. Economic theory argues that WTP for most goods (such as environmental protection) will increase if real
incomes increase. Benefits are therefore adjusted by multiplying the unadjusted benefits by the appropriate adjustment factor to account for income growth over time. For a
complete discussion of how these adjustment factors were derived, we refer the reader to Chapter 9 of the CAND regulatory impact analysis (EPA, 2004). Note that similar
adjustments do not exist for cost-of-illness-based unit values. For these, we apply the same unit value regardless of the future year of analysis.
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Cost-Benefit Analysis
EPA typically estimates the welfare impacts of effects such as changes in recreational
visibility (related to reductions in ambient PM) and agricultural productivity (related to
reductions in ambient ozone) in its RIAs of air quality policy. For the analysis of the proposed
standards, however, we are unable to quantitatively characterize these impacts because of limited
data availability; we are not quantifying ozone benefits related to the proposed standards and the
PM scaling approach does not provide the spatial detail necessary to attribute specific air quality
improvements to specific areas of visual interest (Class I areas). Instead, we discuss these
welfare effects qualitatively in Section 8.5 of this chapter. We also qualitatively describe the
impacts of other environmental and ecological effects for which we do not have an economic
value.
8.4 Benefits Analysis Results for the Proposed Standards
Applying the impact and valuation functions described previously in this chapter to the
estimated changes in PM2.5 associated with the proposed standards results in estimates of the
changes in physical damages (e.g., premature mortalities, cases, admissions) and the associated
monetary values for those changes. Estimates of physical health impacts are presented in Table
8.4-1. Monetized values for those health endpoints are presented in Table 8.4-2, along with total
aggregate monetized benefits. All of the monetary benefits are in constant-year 2005 dollars.
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Draft Regulatory Impact Analysis
Table 8.4-1. Estimated Reduction in Incidence of Adverse Health Effects Related to the
Proposed Standards3
2020 2030
Health Effect Incidence Reduction
PM-Related Endpoints
Premature Mortality13'0
Adult, age 30+ and Infant, age <1 year 290 450
Chronic bronchitis (adult, age 26 and over) 200 290
Nonfatal myocardial infarction (adults, age 18 and older) 490 800
Hospital admissions—respiratory (all ages)d 160 270
Hospital admissions—cardiovascular (adults, age >18)e 130 200
Emergency room visits for asthma (age 18 years and younger) 210 310
Acute bronchitis (children, age 8-12) 470 700
Lower respiratory symptoms (children, age 7-14) 5,600 8,300
Upper respiratory symptoms (asthmatic children, age 9-18) 4,300 6,300
Asthma exacerbation (asthmatic children, age 6-18) 7,000 10,000
Work loss days (adults, age 18-65) 38,000 52,000
Minor restricted-activity days (adults, age 18-65) 220,000 310,000
a Incidences are rounded to two significant digits. PM estimates are nationwide.
b PM premature mortality impacts for adults are based on application of the effect estimate derived from the ACS
cohort study (Pope et al., 2002).41 Infant premature mortality based upon studies by Woodruff, et al 1997.42
0 PM-related mortality benefits estimated using an assumed PM threshold at background levels (3 ug/m3). There
is uncertainty about which threshold to use and this may impact the magnitude of the total benefits estimate. For
a more detailed discussion of this issue, please refer to Section 8.6.2.2 of the RIA.
d Respiratory hospital admissions for PM include admissions for COPD, pneumonia, and asthma.
e Cardiovascular hospital admissions for PM include total cardiovascular and subcategories for ischemic heart
disease, dysrhythmias, and heart failure.
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Cost-Benefit Analysis
Table 8.4-2. Estimated Monetary Value in Reductions in Incidence of Health and Welfare
Effects (in millions of 2005$)a'b
2020 2030
PM-Related Health Effect Estimated Value of Reductions
Premature mortality0'46
Adult, age 30+ and Infant, < 1 year
3% discount rate $2,000 $3,100
7% discount rate $1,800 $2,800
Chronic bronchitis (adults, 26 and over) $94 $140
Non-fatal acute myocardial infarctions
3% discount rate $50 $77
7% discount rate $48 $75
Hospital admissions for respiratory causes $2.9 $5.0
Hospital admissions for cardiovascular causes $3.1 $4.7
Emergency room visits for asthma $0.07 $0.11
Acute bronchitis (children, age 8-12) $0.20 $0.30
Lower respiratory symptoms (children, 7-14) $0.11 $0.16
Upper respiratory symptoms (asthma, 9-11) $0.13 $0.19
Asthma exacerbations $0.36 $0.54
Work loss days $5.8 $7.0
Minor restricted-activity days (MRADs) $14 $19
Monetized Totalf
Base Estimate:
3% discount rate $2,100+B $3,400+B
7% discount rate $1,900+B $3,100+B
Monetary benefits are rounded to two significant digits for ease of presentation and computation. PM benefits are
nationwide.
b Monetary benefits adjusted to account for growth in real GDP per capita between 1990 and the analysis year (2020 or
2030)
0 PM-related mortality benefits estimated using an assumed PM threshold at background levels (3 ug/m3). There
is uncertainty about which threshold to use and this may impact the magnitude of the total benefits estimate. For
a more detailed discussion of this issue, please refer to Section 8.6.2.2 of the RIA.
Valuation assumes discounting over the SAB recommended 20-year segmented lag structure described earlier. Results
reflect the use of 3 percent and 7 percent discount rates consistent with EPA and OMB guidelines for preparing
economic analyses (EPA, 2000; OMB, 2003).43'44
e Adult premature mortality estimates based upon the ACS cohort study (Pope et al., 2002).45 Infant premature
mortality based upon Woodruff et al 1997.
f B represents the monetary value of health and welfare benefits and disbenefits not monetized. A detailed listing is
provided in Table 8.1-2.
In addition to omitted benefits categories such as air toxics, ozone, and various welfare
effects, not all known PM-related health and welfare effects could be quantified or monetized.
Furthermore, we did not quantify reductions in secondary PM2.s and the associated health and
welfare effects. The monetized value of all of these unquantified effects is represented by adding
an unknown "B" to the aggregate total. The estimate of total monetized health benefits of the
proposed control package is thus equal to the subset of monetized PM-related health benefits
plus B, the sum of the nonmonetized health and welfare benefits.
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Draft Regulatory Impact Analysis
Total monetized benefits are dominated by benefits of mortality risk reductions. The
primary estimate projects that the proposed standards will result in 290 avoided premature deaths
annually in 2020 and 450 avoided premature deaths annually in 2030. The increase in annual
benefits from 2020 to 2030 reflects additional emission reductions from the proposed standards,
as well as increases in total population and the average age (and thus baseline mortality risk) of
the population.
Our estimate of total monetized benefits in 2020 for the proposed standards is $2.1 billion
using a three percent discount rate and $1.9 billion using a seven percent discount rate. In 2030,
the monetized benefits are estimated at $3.4 billion using a three percent discount rate and $3.1
billion using a seven percent discount rate. The monetized benefit associated with reductions in
the risk of premature mortality, which accounts for $2.0 billion in 2020 and $3.1 billion in 2030
(assuming a three percent discount rate), is over 90 percent of total monetized health benefits.
The next largest benefit is for reductions in chronic illness (CB and nonfatal heart attacks),
although this value is more than an order of magnitude lower than for premature mortality.
Hospital admissions for respiratory and cardiovascular causes, minor restricted activity days, and
work loss days account for the majority of the remaining benefits. The remaining categories
each account for a small percentage of total benefit; however, they represent a large number of
avoided incidences affecting many individuals. A comparison of the incidence table to the
monetary benefits table reveals that there is not always a close correspondence between the
number of incidences avoided for a given endpoint and the monetary value associated with that
endpoint. For example, there are over 100 times more work loss days than premature mortalities,
yet work loss days account for only a very small fraction of total monetized benefits. This
reflects the fact that many of the less severe health effects, while more common, are valued at a
lower level than the more severe health effects. Also, some effects, such as hospital admissions,
are valued using a proxy measure of willingness-to-pay (e.g., cost-of-illness).H As such, the full
value of these effects may be higher than that reported in Table 8.4-2.
8.5 Unquantified Health and Welfare Effects
In considering the monetized benefits estimates, the reader should remain aware of the
many limitations of conducting the analyses mentioned throughout this RIA. One significant
limitation of both the health and welfare benefits analyses is the inability to quantify many of the
effects listed in Table 8.1-2. For many health and welfare effects, such as changes in health
effects due to reductions in air toxics exposure, changes in ecosystem functions and PM-related
materials damage, reliable impact functions and/or valuation functions are not currently
available. In general, if it were possible to monetize these benefit categories, the benefits
estimates presented in this analysis would increase, although the magnitude of such an increase
is highly uncertain.
Other welfare effects that EPA has monetized in past RIAs, such as recreational
visibility, are omitted from the current analysis. Due to time and resource constraints, we did not
H See Table 12.3-2 for a description of how each particular endpoint is valued.
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run the full-scale PM air quality modeling needed to estimate this benefit category. Instead, we
relied on the PM scaling benefits transfer approach that provides analytical efficiency but
sacrifices the full range of outputs typically generated when models such as the Community
Multiscale Air Quality (CMAQ) model or the Regional Modeling System for Aerosols and
Deposition (REMSAD) are run.
Unquantified benefits are qualitatively discussed in the following health and welfare
effects sections. In addition to unquantified benefits, there may also be environmental costs
(disbenefits) that we are unable to quantify, which we qualitatively discuss as well. The net
effect of excluding benefit and disbenefit categories from the estimate of total benefits depends
on the relative magnitude of the effects. Although we are not currently able to estimate the
magnitude of these unquantified and unmonetized benefits, specific categories merit further
discussion. EPA believes, however, the unquantified benefits associated with health and non-
health benefit categories are likely significant and that their omission lends a downward bias to
the monetized benefits presented in this analysis.
8.5.1 Human Health Impact Assessment
In addition to the PM2.5 health effects discussed above, there is emerging evidence that
human exposure to PM may be associated a number of health effects not quantified in this
analysis (see Table 8.1-2). An improvement in ambient PM2.5 concentrations may reduce the
number of incidences within each of these unquantified effect categories that the U.S. population
would experience. Although these health effects are believed to be PM-induced, effect estimates
are not available for quantifying the benefits associated with reducing these effects.
Furthermore, the health effects associated with reductions in air toxics are not quantified in this
analysis.
The proposed standards will also reduce the national emissions inventory of precursors to
ozone, such as VOCs. Exposure to ozone has been linked to a variety of respiratory effects
including hospital admissions, emergency room visits, minor restricted activity days, worker
productivity and illnesses resulting in school absences. Emerging evidence has also shown that
human exposure to ozone may be associated with a number of other health effects not quantified
in this analysis (see Table 8.1-2). Ozone can also adversely affect the agricultural and forestry
sectors by decreasing yields of crops and forests. Although ozone benefits are typically
quantified in regulatory impact analyses, we have chosen not to evaluate them for this analysis.
As discussed in Chapter 2, the ozone modeling conducted for the proposed standards results in a
net reduction in ambient concentrations of ozone in 2020 and 2030. By omitting ozone benefits
in this proposal, we acknowledge that this analysis underestimates the benefits associated with
the proposed standards.
8.5.2 Welfare Impact Assessment
For many welfare effects, such as changes in ecosystem functions and PM-related
materials damage, reliable impact functions and/or valuation functions are not currently
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available. In general, if it were possible to monetize these benefit categories, the benefits
estimates presented in this analysis would increase, although the magnitude of such an increase
is highly uncertain.
8.5.2.1 Visibility Benefits
Changes in the level of ambient PM2.5 caused by the proposed standards will change the
level of visibility in much of the United States. Visibility directly affects people's enjoyment of
a variety of daily activities. Individuals value visibility both in the places they live and work, in
the places they travel to for recreational purposes, and at sites of unique public value, such as the
Great Smoky Mountains National Park. Though not quantified in this analysis, the value of
improvements in visibility monetized for regulatory analyses such as the final CAIR are
significant. We refer the reader to that analysis for a complete description of the methods used to
value visibility.47
8.5.2.2 gricultural and Forestry Benefits
The Ozone Criteria Document notes that "ozone affects vegetation throughout the United
States, impairing crops, native vegetation, and ecosystems more than any other air pollutant"
(EPA, 1996, page 5-11).48 Though we do not quantify the potential improvements in ambient
ozone concentrations associated with the proposed standards, it is possible that yields will
improve in areas of agricultural or forestry production impacted by the standards.
Well-developed techniques exist to provide monetary estimates of these benefits to
agricultural producers and to consumers. These techniques use models of planting decisions,
yield response functions, and agricultural products' supply and demand. The resulting welfare
measures are based on predicted changes in market prices and production costs. Models also
exist to measure benefits to silvicultural producers and consumers. However, these models have
not been adapted for use in analyzing ozone-related forest impacts. Because of resource
limitations, we are unable to provide agricultural or forestry benefits estimates for the proposed
standards.
8.5.2.2.1 Agricultural Benefits
Laboratory and field experiments have shown reductions in yields for agronomic crops
exposed to ozone, including vegetables (e.g., lettuce) and field crops (e.g., cotton and wheat).
The most extensive field experiments, conducted under the National Crop Loss Assessment
Network (NCLAN), examined 15 species and numerous cultivars. The NCLAN results show
that "several economically important crop species are sensitive to ozone levels typical of those
found in the United States."54 In addition, economic studies have shown a relationship between
observed ozone levels and crop yields.49
8.5.2.2.2Forestry Benefits
Ozone also has been shown conclusively to cause discernible injury to forest trees (EPA,
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1996; Fox and Mickler, 1996).54'50 In our previous analysis of the Heavy-Duty Engine/Diesel
Fuel rule, we were able to quantify the effects of changes in ozone concentrations on tree growth
for a limited set of species.
8.5.2.3 Benefits from Reductions in Materials Damage
The proposed standards that we modeled are expected to produce economic benefits in
the form of reduced materials damage. There are two important categories of these benefits.
Household soiling refers to the accumulation of dirt, dust, and ash on exposed surfaces. PM also
has corrosive effects on commercial/industrial buildings and structures of cultural and historical
significance. The effects on historic buildings and outdoor works of art are of particular concern
because of the uniqueness and irreplaceability of many of these objects.
Previous EPA benefits analyses have been able to provide quantitative estimates of
household soiling damage. Consistent with SAB advice, we determined that the existing data
(based on consumer expenditures from the early 1970s) are too out of date to provide a reliable
estimate of current household soiling damages (EPA-SAB-COUNCIL-ADV-98-003, 1998).51
EPA is unable to estimate any benefits to commercial and industrial entities from reduced
materials damage. Nor is EPA able to estimate the benefits of reductions in PM-related damage
to historic buildings and outdoor works of art. Existing studies of damage to this latter category
in Sweden (Grosclaude and Soguel, 1994)52 indicate that these benefits could be an order of
magnitude larger than household soiling benefits.
8.5.3 UVb Exposure
In contrast to the unquantified benefits of the proposed standards discussed above, it is
also possible that this rule will result in disbenefits in some areas of the United States. The
effects of ozone and PM on radiative transfer in the atmosphere can lead to effects of uncertain
magnitude and direction on the penetration of ultraviolet light and climate. Ground level ozone
makes up a small percentage of total atmospheric ozone (including the stratospheric layer) that
attenuates penetration of ultraviolet - b (UVb) radiation to the ground. EPA's past evaluation of
the information indicates that potential disbenefits would be small, variable, and with too many
uncertainties to attempt quantification of relatively small changes in average ozone levels over
the course of a year.53 EPA's most recent provisional assessment of the currently available
information indicates that potential but unquantifiable benefits may also arise from ozone-related
attenuation of UVb radiation.54 EPA believes that we are unable to quantify any net climate-
related disbenefit or benefit associated with the combined ozone and PM reductions in this rule.
8.6 Methods for Describing Uncertainty
In any complex analysis using estimated parameters and inputs from numerous models, there are
likely to be many sources of uncertainty. This analysis is no exception. As outlined both in this
and preceding chapters, many inputs were used to derive the benefits estimate, including
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emission inventories, air quality models (with their associated parameters and inputs),
epidemiological health effect estimates, estimates of values (both from WTP and COI studies),
population estimates, income estimates, and estimates of the future state of the world (i.e.,
regulations, technology, and human behavior). Each of these inputs may be uncertain and,
depending on its role in the benefits analysis, may have a disproportionately large impact on
estimates of total benefits. For example, emissions estimates are used in the first stage of the
analysis. As such, any uncertainty in emissions estimates will be propagated through the entire
analysis. Some of the key uncertainties in the quantified benefits analysis are presented in Table
8.6-1.
Table 8.6-1. Primary Sources of Uncertainty in the Quantified Benefits Analysis
1. Uncertainties Associated with Impact Functions
• The value of the PM effect estimate in each impact function.
• Application of a single impact function to pollutant changes and populations in all locations.
• Similarity of future-year impact functions to current impact functions.
• Correct functional form of each impact function.
• Extrapolation of effect estimates beyond the range of PM concentrations observed in the source
epidemiological study.
• Application of some impact functions only to those subpopulations matching the original study
population.
2. Uncertainties Associated with PM Concentrations
• Responsiveness of the models to changes in precursor emissions resulting from the control policy.
• Projections of future levels of precursor emissions, especially organic carbonaceous particle emissions.
• Model chemistry for the formation of ambient nitrate concentrations.
• Lack of speciation monitors in some areas requires extrapolation of observed speciation data.
• CMAQ model performance in the Western U.S., especially California indicates significant
underprediction of PM2 5.
3. Uncertainties Associated with PM Mortality Risk
• Differential toxicity of specific component species within the complex mixture of PM has not been
determined.
• The extent to which adverse health effects are associated with low-level exposures that occur many times
in the year versus peak exposures.
• The extent to which effects reported in the long-term exposure studies are associated with historically
higher levels of PM rather than the levels occurring during the period of study.
• Reliability of the limited ambient PM2 5 monitoring data in reflecting actual PM2 5 exposures.
5. Uncertainties Associated with Possible Lagged Effects
• The portion of the PM-related long-term exposure mortality effects associated with changes in annual PM
levels that would occur in a single year is uncertain as well as the portion that might occur in subsequent
years.
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6. Uncertainties Associated with Baseline Incidence Rates
• Some baseline incidence rates are not location specific (e.g., those taken from studies) and therefore may
not accurately represent the actual location-specific rates.
• Current baseline incidence rates may not approximate well baseline incidence rates in 2020 and 2030.
• Projected population and demographics may not represent well future-year population and demographics.
7. Uncertainties Associated with Economic Valuation
• Unit dollar values associated with health and welfare endpoints are only estimates of mean WTP and
therefore have uncertainty surrounding them.
• Mean WTP (in constant dollars) for each type of risk reduction may differ from current estimates because
of differences in income or other factors.
8. Uncertainties Associated with Aggregation of Monetized Benefits
• Health and welfare benefits estimates are limited to the available impact functions. Thus, unqualified or
unmonetized benefits are not included.
As part of EPA's approach to characterizing uncertainties in the benefits assessment, we
generate a probabilistic estimate of statistical uncertainty based on standard errors reported in the
underlying studies used in the benefits modeling framework, with particular emphasis on the
health impact functions. Using a Monte Carlo procedure, the distribution of each health endpoint
and its unit dollar value is characterized by the reported mean and standard error derived from
the epidemiology and valuation literature. Details on the distributions used to value individual
health endpoints are provided in Section 8.6.1, as well as in the CAIR RIA (Appendix B; EPA,
2005).55 It should be noted that the Monte Carlo-generated distributions of benefits reflect only
some of the uncertainties in the input parameters (described in Table 8.6-1). Uncertainties
associated with emissions, air quality modeling, populations, and baseline health effect incidence
rates are not represented in the distributions of benefits of attaining alternative standards. Issues
such as correlation between input parameters and the identification of reasonable upper and
lower bounds for input distributions characterizing uncertainty in additional model elements will
be addressed in future versions of the uncertainty framework.
In benefit analyses of air pollution regulations conducted to date, the estimated impact of
reductions in premature mortality has accounted for 85% to 95% of total benefits. Therefore, in
characterizing the uncertainty related to the estimates of total benefits it is particularly important
to attempt to characterize the uncertainties associated with this endpoint. As such, we
specifically discuss the uncertainty related to PM-related premature mortality in Section 8.6.2.
8.6.1 Analysis of Statistical Uncertainty
For the proposed standards, we did not attempt to assign probabilities to all of the
uncertain parameters in the model because of a lack of resources and reliable methods. At this
time, we simply generate estimates of the distributions of dollar benefits for PM health effects
and for total dollar benefits. For all quantified PM endpoints, we scaled the likelihood
distributions of the benefit estimates from the CAND uncertainty analysis,1 based on the same
1 U.S. Environmental Protection Agency. May 2004. Final Regulatory Analysis: Control of Emissions from
Nonroad Diesel Engines. Prepared by: Office of Air and Radiation. Available at http://www.epa.gov/nonroad-
diesel/2004fr.htm#documents. Accessed December 15, 2005.
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benefits transfer approach we used to estimate the benefits of the standards presented in Section
8.2. The CAND likelihood distributions were based solely on the statistical uncertainty
surrounding the estimated C-R functions and the assumed distributions around the unit values.
We use the benefits transfer approach to scale those distributions to reflect the predicted PM
precursor emission reductions of the proposed standards. Though the scaling approach adds
another element of uncertainty that we cannot characterize in the distributions, we believe the
scaled uncertainty is a reasonable approximation of the statistical uncertainty based on standard
errors reported in the underlying epidemiological and valuation studies.
Our scaled estimates of the likelihood distributions for health-related PM benefits should
be viewed as incomplete because of the wide range of sources of uncertainty that we have not
incorporated. The 5th and 95th percentile points of our scaled estimate are based on statistical
error, and cross-study variability provides some insight into how uncertain our estimate is with
regard to those sources of uncertainty. However, it does not capture other sources of uncertainty
regarding the benefits transfer scaling approach or the inputs to the CAND modeling upon which
the scaling is based, including emissions, air quality, baseline population incidence, and
projected exposures. It also does not account for aspects of the health science not captured in the
studies, such as the likelihood that PM is causally related to premature mortality and other
serious health effects. Thus, a likelihood description based on the standard error would provide a
misleading picture about the overall uncertainty in the estimates.
Both the uncertainty about incidence changesJ and uncertainty about unit dollar values
can be characterized by distributions. Each "likelihood distribution" characterizes our beliefs
about what the true value of an unknown variable (e.g., the true change in incidence of a given
health effect in relation to PM exposure) is likely to be, based on the available information from
relevant studies.K Unlike a sampling distribution (which describes the possible values that an
estimator of an unknown variable might take on), this likelihood distribution describes our
beliefs about what values the unknown variable itself might be. Such likelihood distributions
can be constructed for each underlying unknown variable (such as a particular pollutant
coefficient for a particular location) or for a function of several underlying unknown variables
(such as the total dollar benefit of a regulation). In either case, a likelihood distribution is a
characterization of our beliefs about what the unknown variable (or the function of unknown
variables) is likely to be, based on all the available relevant information. A likelihood
description based on such distributions is typically expressed as the interval from the 5th
percentile point of the likelihood distribution to the 95th percentile point. If all uncertainty had
been included, this range would be the "credible range" within which we believe the true value is
likely to lie with 90 percent probability.
1 Because this is a national analysis in which, for each endpoint, a single C-R function is applied everywhere, there
are two sources of uncertainty about incidence: statistical uncertainty (due to sampling error) about the true value of
the pollutant coefficient in the location where the C-R function was estimated and uncertainty about how well any
given pollutant coefficient approximates (3*.
K Although such a "likelihood distribution" is not formally a Bayesian posterior distribution, it is very similar in
concept and function (see, for example, the discussion of the Bayesian approach in Kennedy, 1990. A Guide to
Econometrics. 2nd ed. MIT Press: Cambridge, MA., pp. 168-172).
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8.6.1.1 Monte Carlo Approach
The uncertainty about the total dollar benefit associated with any single endpoint
combines the uncertainties from these two sources (the C-R relationship and the valuation) and is
estimated with a Monte Carlo method. In each iteration of the Monte Carlo procedure, a value is
randomly drawn from the incidence distribution, another value is randomly drawn from the unit
dollar value distribution; the total dollar benefit for that iteration is the product of the two.L
When this is repeated for many (e.g., thousands of) iterations, the distribution of total dollar
benefits associated with the endpoint is generated.
Using this Monte Carlo procedure, a distribution of dollar benefits can be generated for
each endpoint. As the number of Monte Carlo draws gets larger and larger, the Monte Carlo-
generated distribution becomes a better and better approximation of a joint likelihood
distribution (for the considered parameters) making up the total monetary benefits for the
endpoint.
After endpoint-specific distributions are generated, the same Monte Carlo procedure can
then be used to combine the dollar benefits from different (nonoverlapping) endpoints to
generate a distribution of total dollar benefits.
The estimate of total benefits may be thought of as the end result of a sequential process
in which, at each step, the estimate of benefits from an additional source is added. Each time an
estimate of dollar benefits from a new source (e.g., a new health endpoint) is added to the
previous estimate of total dollar benefits, the estimated total dollar benefits increases. However,
our bounding or likelihood description of where the true total value lies also increases as we add
more sources.
As an example, consider the benefits from reductions in PM-related hospital admissions
for cardiovascular disease. Because the actual dollar value is unknown, it may be described
using a variable, with a distribution describing the possible values it might have. If this variable
is denoted as XI, then the mean of the distribution, E(X1) and the variance of XI, denoted
Var(Xl), and the 5th and 95th percentile points of the distribution (related to Var(Xl)), are ways
to describe the likelihood for the true but unknown value for the benefits reduction.
Now suppose the benefits from reductions in PM-related hospital admissions for
respiratory diseases are added. Like the benefits from reductions in PM-related hospital
admissions for cardiovascular disease, the likelihood distribution for where we expect the true
value to be may be considered a variable, with a distribution. Denoting this variable as X2, the
benefits from reductions in the incidence of both types of hospital admissions is XI + X2. This
variable has a distribution with mean E(X1 + X2) = E(X1) + E(X2), and a variance of Var(Xl +
L This method assumes that the incidence change and the unit dollar value for an endpoint are stochastically
independent.
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X2) = Var(Xl) + Var(X2) + 2Cov(Xl,X2); if XI and X2 are stochastically independent, then it
has a variance of Var(Xl + X2) = Var(Xl) + Var(X2), and the covariance term is zero.
The benefits from reductions in all nonoverlapping PM-related health and welfare
endpoints are (Xm+1, ..., Xn) is X = XI + ... + Xn. The mean of the distribution of total
benefits, X, is
E(X) = E(X1) + E(X2) + ... + E(Xn)
and the variance of the distribution of total benefits—assuming that the components are
stochastically independent of each other (i.e., no covariance between variables), is
Var(X) = Var(Xl) + Var(X2) + ... + Var(Xn)
If all the means are positive, then each additional source of benefits increases the point estimate
(mean) of total benefits. However, with the addition of each new source of benefits, the variance
of the estimate of total benefits also increases. That is,
E(X1) < E(X1 + X2) < E(X1 + X2 + X3) < ... < E(X1 + ... + Xn) = E(X)
Var(Xl) < Var(Xl + X2) < Var(Xl + X2 + X3) < ... < Var(Xl + ... + Xn) = Var(X)
That is, the addition of each new source of benefits results in a larger mean estimate of total
benefits (as more and more sources of benefits are included in the total) about which there is less
certainty. This phenomenon occurs whenever estimates of benefits are added.
Calculated with a Monte Carlo procedure, the distribution of X is composed of random
draws from the components of X. In the first draw, a value is drawn from each of the
distributions, XI, X2, through Xn; these values are summed; and the procedure is repeated again,
with the number of repetitions set at a high enough value (e.g., 5,000) to reasonably trace out the
distribution of X. The 5th percentile point of the distribution of X will be composed of points
pulled from all points along the distributions of the individual components and not simply from
the 5th percentile. Although the sum of the 5th percentiles of the components would be
represented in the distribution of X generated by the Monte Carlo, it is likely that this value
would occur at a significantly lower percentile. For a similar reason, the 95th percentile of X
will be less than the sum of the 95th percentiles of the components, and instead the 95th
percentile of X will be composed of component values that are significantly lower than the 95th
percentiles.
The physical effects estimated in this analysis are assumed to occur independently. It is
possible that, for any given pollution level, there is some correlation between the occurrence of
physical effects, due to say avoidance behavior or common causal pathways and treatments (e.g.,
stroke, some kidney disease, and heart attack are related to treatable blood pressure). Estimating
accurately any such correlation, however, is beyond the scope of this analysis, and instead it is
simply assumed that the physical effects occur independently.
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8.6.1.2 Monte Carlo Results
Based on the Monte Carlo techniques and benefits transfer methods described above, we
scaled the CAND likelihood distributions for the dollar value of total PM health-related benefits
for the proposed standards. For this analysis, the likelihood descriptions for the true value of
each of the health endpoint incidence estimates, including premature mortality, were based on
classical statistical uncertainty measures. The measures include the mean and standard deviation
of the C-R relationships in the epidemiological literature, and assumptions of particular
likelihood distribution shapes for the valuation of each health endpoint value based on reported
values in the economic literature. The distributions for the value used to represent incidence of a
health effect in the total benefits valuation represent both the simple statistical uncertainty
surrounding individual effect estimates and, for those health endpoints with multiple effects from
different epidemiology studies, interstudy variability. Distributions for unit dollar values are
summarized in Table 8.3-2.
Results of the scaled Monte Carlo simulations are presented in Table 8.6-2. The table
provides the scaled means of the distributions and the estimated 5th and 95th percentiles of the
distributions. The contribution of mortality to the mean benefits and to both the 5th and 95th
percentiles of total benefits is substantial, with mortality accounting for over 90 percent of the
mean estimate, and even the 5th percentile of mortality benefits dominating close to the 95th
percentile of all other benefit categories. Thus, the choice of value and the shape for likelihood
distribution for VSL should be examined closely and is key information to provide to decision
makers for any decision involving this variable. The 95th percentile of total benefits is
approximately twice the mean, while the 5th percentile is approximately one-fourth of the mean.
The overall range from 5th to 95th represents about one order of magnitude.
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Table 8.6-2. Distribution of Value of Annual PM-Related Human Health Benefits in 2030
for the Proposed Standards"
Endpoint
Monetary Benefits'1' c (Millions 2003$, Adjusted for Income
Growth)
5th Percentile Mean 95th Percentile
Premature mortality0, Long-term exposure
Adults, 30+ yrs and Infants,
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8.6.2 Additional Approaches to Characterizing Uncertainty Related to PM-Mortality
As part of an overall program to improve the Agency's characterization of uncertainties in
health benefits analyses, we attempt to address uncertainties associated with the PM2.5 mortality
health impact function relationship and valuation. Use of the ACS cohort (Pope et al., 2002)
mortality function to support this analysis does not address uncertainty associated with: (a)
potential of the study to incompletely capture short-term exposure-related mortality effects, (b)
potential mis-match between study and analysis populations which introduces various forms of
bias into the results, (c) failure to identify all key confounders and effects modifiers, which could
result in incorrect effects estimates relating mortality to PM2.5 exposure, and (d) model
uncertainty. EPA is researching methods to characterize all elements of uncertainty in the dose-
response function for mortality.
As is discussed in detail in the final PM NAAQS RIA, EPA uses three methods to
quantify uncertainties in the mortality function, including: the statistical uncertainty derived from
the standard errors reported in the ACS cohort study, the presentation of additional estimates of
mortality based upon the peer-reviewed literature, and the use of results of an expert elicitation
conducted to explore a more thorough characterization of uncertainties in the mortality estimate.
Because this analysis utilizes the PM scaling benefits transfer approach to estimate mortality
incidence for the proposed standards, we cannot quantify the PM mortality uncertainty to the
same extent as was done for the CAIR or PM NAAQS analyses. However, in a similar fashion
to the analysis conducted for the Clean Air Visibility Rule (CAVR),56 we can scale the results of
the CAND mortality uncertainly analysis to the PM precursor emission changes modeled for the
proposed standards.
8.6.2.1 Uncertainty Associated with the Concentration-Response Function
In the benefit analysis of the CAND 2030 emission control standards, the statistical
uncertainty represented by the standard error of the American Cancer Society cohort study (Pope
et al, 2002) was one and one-half times the mean benefit estimate at the 95th percentile and less
than one-half of the mean at the 5th percentile. The CAND analysis also derived mortality from
the reanalysis of the Harvard Six-Cities study (Krewski et al., 2000).57 At the time of the CAND
analysis, EPA's Science Advisory Board provided guidance stating, "The Six-Cities estimates
may be used in a sensitivity analysis to demonstrate that with different but also plausible
selection criteria for C-R functions, benefits may be considerably larger than suggested by the
ACS study." (EPA-SAB-COUNCIL-ADV-04-002).58 In the CAND analysis, the Harvard Six-
Cities mean benefits estimate was over twice the size of the mean estimate of mortality benefits
derived from the ACS study.
Recently, a new peer-reviewed extension of the Six-Cities study has been published
(Laden et al., 2006).59 This follow-up to the Harvard Six-Cities study both confirmed the effect
size from the first analysis and provided additional evidence that reductions in PM2.5 are likely
associations with reductions in the risk of premature death. This additional evidence stems from
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the observed reductions in PM2.s in each city during the extended follow-up period. Laden et al.
(2006) found that mortality rates consistently went down at a rate proportionate to the observed
reductions in PM2 5. In the recently finalized PM NAAQS RIA, results from this study were
presented as an additional estimate of premature mortality benefits along with the benefits
derived from the ACS study. The mean benefits estimate derived from the Six-Cities study was
more than twice the size of the mean estimate of mortality benefits derived from the ACS study.
Because this study was not available during the CAND analysis, from which the benefits of the
proposed standards are scaled, we are unable to provide an estimate of mortality benefits based
on the Six-Cities study for this proposed analysis. However, based on the relationship between
the Six-Cities study and the ACS cohort study observed in the final PM NAAQS RIA, we can
surmise that the mean estimate of PM-related mortality associated with the proposed standards
could be approximately twice as large. For a full discussion of the epidemiological basis of
EPA's premature mortality estimates, we refer the reader to Chapter 5.1 of the final PM NAAQS
RIA.
EPA recently completed a full-scale expert elicitation that incorporated peer-review
comments on the pilot application used in CAND, and that provides a more robust
characterization of the uncertainty in the premature mortality function. This expert elicitation
was designed to evaluate uncertainty in the underlying causal relationship, the form of the
mortality impact function (e.g., threshold versus linear models) and the fit of a specific model to
the data (e.g., confidence bounds for specific percentiles of the mortality effect estimates).
Additional issues, such as the ability of long-term cohort studies to capture premature mortality
resulting from short-term peak PM exposures, were also addressed in the expert elicitation. The
recently published RIA supporting the Particulate Matter National Ambient Air Quality
Standards (PM NAAQS) used the results of this expert elicitation to quantitatively characterize
uncertainty.
Due to the analytical constraints associated with the PM benefits scaling approach, we are
unable to assess the premature mortality health impacts derived from the formally elicited expert
judgments. Compared to the final PM NAAQS estimate of mean premature mortality derived
from the ACS cohort study, however, expert-based mortality incidence ranged from
approximately 50 percent of the mean ACS estimate to approximately five times the size of the
mean ACS estimate. In total, PM-related premature mortality derived from eleven of the experts
was greater than the ACS estimate, while one expert-based estimate fell below the ACS result.
8.6.2.2 PM2.5-Mortality Cutpoint/Threshold Analysis
Another source of uncertainty that has received recent attention from several scientific
review panels is the shape of the concentration-response function for PM-related mortality, and
specifically whether there exists a threshold below which there would be no benefit to further
reductions in PM2.5. The consistent advice from EPA's SABM has been to model premature
M The advice from the 2004 SAB-HES (EPA-SAB-COUNCIL-ADV-04-002)69 is characterized by the following:
"For the studies of long-term exposure, the HES notes that Krewski et al. (2000) have conducted the most careful
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mortality associated with PM exposure as a nonthreshold effect, that is, with harmful effects to
exposed populations regardless of the absolute level of ambient PM concentrations. However,
EPA's most recent PM2.5 Criteria Document concludes that "the available evidence does not
either support or refute the existence of thresholds for the effects of PM on mortality across the
range of concentrations in the studies."60 Some researchers have hypothesized the presence of a
threshold relationship. That is, the hypothesized relationship includes the possibility that there
exists a PM concentration level below which further reductions no longer yield premature
mortality reduction benefits.
To consider the impact of a threshold in the response function for the chronic mortality
endpoint, the final PM NAAQS RIA61 constructed a sensitivity analysis by assigning different
cutpoints below which changes in PM2.5 are assumed to have no impact on premature mortality.
In applying the cutpoints, the PM NAAQS analysis adjusted the mortality function slopes
accordingly.N Five cutpoints (including the base case assumption) were included in the
sensitivity analysis: (a) 14 |ig/m3 (assumes no impacts below a level being considered at the time
for the annual PM2.5 NAAQS), (b) 12 |ig/m3 (c) 10 |ig/m3 (reflects comments from CASAC,
2005), 62 (d) 7.5 |ig/m3 (reflects recommendations from SAB-HES to consider estimating
mortality benefits down to the lowest exposure levels considered in the ACS cohort study (Pope
et al., 2002) used as the basis for modeling chronic mortality) 63 and (e) background or 3 |ig/m3
(reflects NRC recommendation to consider effects all the way to background).64 The results of
the sensitivity analysis displayed the change in avoided mortality cases and associated monetary
benefits associated with the alternative cutpoints (see the final PM NAAQS RIA, Chapter 5.1
and Tables 5-28 to 5-31).
A sensitivity analysis such as this can be difficult to interpret, because when a threshold
above the lowest observed level of PM2.s in the underlying ACS cohort study (Pope et al., 2002)
is assumed, the slope of the concentration-response function above that level must be adjusted
upwards to account for the assumed threshold.0 Depending on the amount of slope adjustment
and the proportion of the population exposed above the assumed threshold, the estimated
mortality impact can either be lower (if most of the exposures occur below the threshold) or
higher (if most of the exposures occur above the threshold). To demonstrate this, we present an
example from the proposed PM NAAQS RIA. In its examination of the benefits of attaining
alternative PM NAAQS in Chicago/ the analysis found that, because annual mean levels are
generally higher in Chicago, there was a two-part pattern to the relationship between assumed
work on this issue. They report that the associations between PM25 and both all-cause and cardiopulmonary
mortality were near linear within the relevant ranges, with no apparent threshold. Graphical analyses of these
studies (Dockery et al., 1993, Figure 3, and Krewski et al., 2000, page 162) also suggest a continuum of effects
down to lower levels. Therefore, it is reasonable for EPA to assume a no threshold model down to, at least, the low
end of the concentrations reported in the studies."
N Note that the PM NAAQS analysis only adjusted the mortality slopes for the 10 ug/m3, 12 ug/m3 and 14 ug/m3
cutpoints since the 7.5 ug/m3 and background cutpoints were at or below the lowest measured exposure levels
reported in the Pope et al. (2002) study for the combined exposure dataset.
0 See NAS (2002)71 and CASAC (2005)68 for discussions of this issue.
p See the proposed PM NAAQS RIA (2005),67 Appendix A, pp. A63-A64.
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Draft Regulatory Impact Analysis
threshold and mortality impacts. As the threshold increased from background to 7.5 ug/m3, the
mortality impact fell (because there is no slope adjustment). However, at an assumed threshold
of 10 ug/m3, estimated mortality impacts actually increased, because the populations exposed
above 10 ug/m3 were assumed to have a larger response to particulate matter reductions (due to
the increased slope above the assumed threshold). And finally, mortality impacts again fell to
zero if a 15 ug/m3 threshold was assumed, because these impacts were measured incremental to
attainment of the current standard.
We are unable to do this type of sensitivity analysis for the analysis of the proposed
standards because of the analytical limitations of the PM benefits scaling procedure. When EPA
conducted the CAND analysis (from which the primary estimates of benefits for the proposed
standards are based), there were no PM mortality concentration-response functions with the
slope adjusted upwards to account for an assumed threshold. Instead, our primary PM benefits
estimate for the proposed standards reflects a background threshold assumption of 3 ug/m3. We
present in Table 8.6-3 the results of our scaled PM-related mortality benefits in the context of its
relationship to other cutpoints.
Table 8.6-3. PM-Related Mortality Benefits of the Proposed Standards: Cutpoint
Sensitivity Analysis3
Certainty that Benefits are
At Least Specified Value
More Certain that Benefits
Are at Least as Large
^
V
7
Less Certain that Benefits
Are at Least as Large
Level of Assumed
Threshold
14 ug/m3 c
12 ug/m3
10 ug/m3 d
7.5 ug/m3 e
3 ug/m3 f
Discount
Rate
3%
7%
3%
7%
3%
7%
3%
7%
3%
7%
PM Mortality Benefits (Billion 2003$)
2020 2030
N/Ab
N/A
N/A
N/A
$3.3 $6.3
$3.0 $5.7
a Note that this table only presents the effects of a outpoint on PM-related mortality incidence and valuation
estimates.
b Not Available. We are unable to provide cutpoint analysis results for the proposed standards because of the
analytical limitations of the PM benefits scaling procedure.
0 EPA intends to analyze a cutpoint between 12 ug/m3and 15 ug/m3 for the final RIA.
d CASAC (2005)68
e SAB-HES (2004)69
fNAS(2002)71
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Cost-Benefit Analysis
8.7 Health-Based Cost Effectiveness Analysis
Health-based cost-effectiveness analysis (CEA) and cost-utility analysis (CUA) have
been used to analyze numerous health interventions but have not been widely adopted as tools to
analyze environmental policies. The Office of Management and Budget (OMB) issued Circular
A-4 guidance on regulatory analyses, requiring Federal agencies to "prepare a CEA for all major
rulemakings for which the primary benefits are improved public health and safety to the extent
that a valid effectiveness measure can be developed to represent expected health and safety
outcomes." Environmental quality improvements may have multiple health and ecological
benefits, making application of CEA more difficult and less straightforward. For the CAIR
analysis, the first to incorporate an analysis of this kind, CEA provided a useful framework for
evaluation: nonhealth benefits were substantial, but the majority of quantified benefits came
from health effects. EPA included in the CAIR RIA a preliminary and experimental application
of one type of CEA—a modified quality-adjusted life-years (QALYs) approach. For CAIR,
EPA concluded that the direct usefulness of cost-effectiveness analysis is mitigated by the lack
of rule alternatives to compare relative effectiveness, but that comparisons could still be made to
other benchmarks bearing in mind methodological differences.
QALYs were developed to evaluate the effectiveness of individual medical treatments,
and EPA is still evaluating the appropriate methods for CEA of environmental regulations.
Agency concerns with the standard QALY methodology include the treatment of people with
fewer years to live (the elderly); fairness to people with preexisting conditions that may lead to
reduced life expectancy and reduced quality of life; and how the analysis should best account for
nonhealth benefits, such as improved visibility.
The Institute of Medicine (a member institution of the National Academies of Science)
established the Committee to Evaluate Measures of Health Benefits for Environmental, Health,
and Safety Regulation to assess the scientific validity, ethical implications, and practical utility
of a wide range of effectiveness measures used or proposed in CEA. This committee prepared a
report titled "Valuing Health for Regulatory Cost-Effectiveness Analysis," which concluded that
CEA is a useful tool for assessing regulatory interventions to promote human health and safety,
although not sufficient for informed regulatory decisions (Miller, Robinson, and Lawrence,
2006).65 They emphasized the need for additional data and methodological improvements for
CEA analyses, and urged greater consistency in the reporting of assumptions, data elements, and
analytic methods. They also provided a number of recommendations for the conduct of
regulatory CEA analyses. EPA is evaluating these recommendations and will determine a
response for upcoming analyses.
In Appendix G of the RIA for the CAIR,63 EPA conducted an extensive cost-
effectiveness analysis using morbidity inclusive life years (MILY). That analysis concluded that
reductions in PM2 5 associated with CAIR were expected to be cost-saving (because the value of
expenditures on illnesses and non-health benefits exceeded costs), and that costs of the CAIR
could have been significantly higher and still result in cost-effective improvements in public
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Draft Regulatory Impact Analysis
health. Because the current analysis relies on a benefits transfer approach to estimate PM-related
benefits, scaling PM benefits from the CAND rule, we do not have the necessary inputs to
develop a valid cost-effectiveness measure for the proposed standards. Furthermore, the CAND
analysis did not include a health-based CEA, the results of which might have been scaled in a
similar fashion to the benefits.
For the CAVR rule, EPA was able to draw inferences from the CAIR CEA by scaling the
relative magnitude of the costs and health impacts between the two rules.66 While the CAVR
was not expected to be cost-saving like CAIR, EPA expected that CAVR was likely to have a
relatively low cost per MILY. For the proposed standards, however, it is difficult to draw similar
inferences with CAIR because the geographic distribution of emission changes, the distribution
of those changes over time, and the age distribution of the mortality and chronic disease
reductions are all expected to differ between the two rules. For these reasons, we do not scale
the CAIR health-based cost-effectiveness analysis for the proposed standards.
8.8 Comparison of Costs and Benefits
The proposed rule establishes separate standards that reduce the evaporative and exhaust
emissions from small SI and marine SI engines. A full appreciation of the overall economic
consequences of these provisions requires consideration of the benefits and costs expected to
result from each standard. Due to limitations in data availability and analytical methods,
however, we are only able to present the benefits of the entire proposed rule in the aggregate for
both PM2.5 and ozone. There are also a number of health and environmental effects associated
with the proposed standards that we were unable to quantify or monetize (see Table 8.1-2).
Table 8.8-1 contains the estimates of monetized benefits of the proposed standards and
estimated social welfare costs for each of the proposed control programs.*2 The annual social
welfare costs of all provisions of this proposed rule are described more fully in Chapter 9. The
results in Table 8.8-1 suggest that the 2020 and 2030 monetized benefits of the proposed
standards are much greater than the expected social welfare costs. Specifically, the annual
benefits of the program would be approximately $2.1 + B billion annually in 2020 using a three
percent discount rate (or $1.9 + B billion using a seven percent discount rate), compared to
estimated social welfare costs of approximately $252 million in that same year. The net benefits
are expected to increase to $3.4 + B billion annually in 2030 using a three percent discount rate
(or $3.1 + B billion using a seven percent discount rate), even as the social welfare costs of that
program fall to $241 million.
In Table 8.8-1, we present the costs and PM-related benefits related to each of the two
broad engine classes regulated by the proposed standards: Small SI and Marine SI engines.
Table 8.8-1 also presents the costs and PM-related benefits related to the specific engine classes
regulated by the proposed standards: Small SI - Class I, Class II, and Handheld (HH); Marine SI
Q Social costs represent the welfare costs of the rule to society. These social costs do not consider transfer payments
(such as taxes) that are simply redistributions of wealth.
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Cost-Benefit Analysis
- Sterndrive/Inboard (SD/I), and Outboard/Personal Water Craft (OB/PWC). Using the same
PM scaling approach described in Section 8.2.2., we are able to split out the estimated PM
benefits related to the different Small SI and Marine SI engine classes. One can see that in all
cases, the PM benefits accrued by the engine classes are greater than the costs, even when fuel
savings is not factored into the cost estimate. The benefit-to-cost ratio would be even greater if
we estimated the ozone benefits related to the proposed standards.
Table 8.8-1. Summary of Annual Benefits and Costs of the Proposed Standards3
(Millions of 2005 dollars)
Description
Estimated Social Welfare Costsb'c
Small SI
Class I
Class II
HHd
Marine SI
SD/I
OB/PWC
Total
Fuel Savings
Total Social Welfare Costs
Estimated Benefits6''
PM-Only Small SI Benefits
3 percent discount rate
7 percent discount rate
Class I
3 percent discount rate
7 percent discount rate
Class II
3 percent discount rate
7 percent discount rate
PM-Only Marine SI Benefits
3 percent discount rate
7 percent discount rate
SD/I
3 percent discount rate
7 percent discount rate
OB/PWC
3 percent discount rate
7 percent discount rate
Total Benefits8
3 percent discount rate
7 percent discount rate
Annual Net Benefits (Total Benefits-Total Costs)8
3 percent discount rate
7 percent discount rate
2020
(Millions of 2005
dollars)
$351
$145
$199
$7
$154
$41
$113
$505
$(253)
$252
$861
$782
$478
$434
$383
$348
$1,280
$1,160
$209
$190
$1,070
$969
$2,140+B
$1,940+B
$1,890+B
$1,690+B
2030
(Millions of 2005
dollars)
$404
$167
$229
$8
$164
$44
$120
$569
$(327)
$241
$1,280
$1,160
$647
$587
$627
$570
$2,110
$1,190
$487
$442
$1,620
$1,470
$3,380+B
$3,070+B
$3,140+B
$2,830+B
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Draft Regulatory Impact Analysis
a All estimates are rounded to three significant digits and represent annualized benefits and costs anticipated for the years 2020
and 2030. Columnar totals may not sum due to rounding.
bNote that costs are the annual total costs of reducing all pollutants associated with each provision of the proposed control
package, while the benefits reflect the value of reductions in PM2 5 only.
0 To calculate annual fixed costs, we use a 7 percent average before-tax rate of return on private capital (see Chapter 9). We do
not present annual costs using an alternative rate of return. In Chapter 9, however, we use both a 3 percent and 7 percent social
discount rate to calculate the net present value of total social costs consistent with EPA and OMB guidelines for preparing
economic analyses (US EPA, 2000 and OMB, 2003).R'S
d Handheld emission reductions associated with the proposed standards, volatile organic hydrocarbons, are not accounted for in
the PM benefits scaling approach. The PM benefit scaling approach is based upon changes in NOx and direct PM2 5 (see section
8.2). We therefore do not estimate any PM-related benefits associated with emission reductions in the handheld engine class.
e PM-related benefits in this table are nationwide.
f Valuation of premature mortality based on long-term PM exposure assumes discounting over the SAB recommended 20-year
segmented lag structure described in section 8.3. Valuation of non-fatal myocardial infarctions is based on the cost-of-illness
over a 5-year period after the incident. The valuation of both endpoints therefore requires the use of a discount rate. We present
the PM-related benefits results using a 3 percent and 7 percent social discount rate consistent with EPA and OMB guidelines for
preparing economic analyses (US EPA, 2000 and OMB, 2003).
gNot all possible benefits or disbenefits are quantified and monetized in this analysis. B is the sum of all unquantified benefits
and disbenefits. Potential benefit categories that have not been quantified and monetized are listed in Table 8.1-2.
RU.S. Environmental Protection Agency, 2000. Guidelines for Preparing Economic Analyses.
www.vosemite 1 .epa.gov/ee/epa/eed/hsf/pages/Guideline.html.
s Office of Management and Budget, The Executive Office of the President, 2003. Circular A-4.
http://www.whitehouse.gov/omb/circulars.
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52 Grosclaude, P., and N.C. Soguel. 1994. "Valuing Damage to Historic Buildings Using a Contingent Market: A
Case Study of Road Traffic Externalities." Journal of Environmental Planning and Management 37: 279-287.
53 U.S. Environmental Protection Agency. 2005. Air Quality Criteria for Ozone and Related Photochemical
Oxidants (First External Review Draft). January. http://cfpub.epa.gov/ncea/cfm/recordisplav.cfm?deid= 114523
54 EPA, 2005. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Second External Review Draft).
August, http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid= 137307
55 U.S. Environmental Protection Agency. March 2005. Regulatory Impact Analysis for the Final Clean Air
Interstate Rule. Prepared by: Office of Air and Radiation. Available at http://www.epa.gov/cair. Accessed
December 15, 2005.
56 U.S. Environmental Protection Agency. June 2005. Regulatory Impact Analysis for the Final Clean Air Visibility
Rule or the Guidelines for Best Available Retrofit Technology (BART) Determinations Under the Regional Haze
Regulations. Prepared by: Office of Air and Radiation. Available at
http://www.epa.gov/visibilitv/pdfs/bart ria 2005 6 15.pdf. Accessed December 15, 2005.
57 Krewski D., R.T. Burnett, M.S. Goldbert, K. Hoover, J. Siemiatycki, M. Jerrett, M. Abrahamowicz, and W.H.
White. July 2000. Reanalysis of the Harvard Six Cities Study and the American Cancer Society Study of
Particulate Air Pollution and Mortality. Special Report to the Health Effects Institute, Cambridge MA.
58 EPA-SAB-COUNCIL_ADV_04-002. March 2004. Advisory on Plans for Health Effects Analysis in the
Analytical Plan for EPA 's Second Prospective Analysis - Benefits and Costs of the Clean Air Act, 1990-2020:
Advisory by the Health Effects Subcommittee of the Advisory Council on Clean Air Compliance Analysis.
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Draft Regulatory Impact Analysis
59 Laden, F., J. Schwartz, F.E. Speizer, and D. W. Dockery. 2006. Reduction in Fine Paniculate Air Pollution and
Mortality. American Journal of Respiratory and Critical Care Medicine. 173: 667-672.
60 U.S. EPA. 2004. Air Quality Criteria for Paniculate Matter, Volume II. Office of Research and Development.
EPA/600/P-99/002bF, October.
61 U.S. Environmental Protection Agency. October 2006. Final Regulatory Impact Analysis (RIA) for the Proposed
National Ambient Air Quality Standards for Particulate Matter. Prepared by: Office of Air and Radiation.
Available at http://www.epa.gov/ttn/ecas/ria.html Accessed October 18, 2006.
62 Clean Air Science Advisory Committee. June 2005. EPA 's Review of the National Ambient Air Quality
Standards for Particulate Matter (Second Draft PM Staff Paper, January 2005). A Review by the PM Review Panel
of the EPA Clean Air Science Advisory Committee. EPASAB-CASAC-05-007.
63 EPA-SAB-COUNCIL_ADV_04-002. March 2004. Advisory on Plans for Health Effects Analysis in the
Analytical Plan for EPA 's Second Prospective Analysis - Benefits and Costs of the Clean Air Act, 1990-2020:
Advisory by the Health Effects Subcommittee of the Advisory Council on Clean Air Compliance Analysis.
64 National Research Council (NRC). 2002. Estimating the Public Health Benefits of Proposed Air Pollution
Regulations. Washington, DC: The National Academies Press.
65 Miller W, Robinson LA, Lawrence RS, eds. Valuing Health: Cost Effectiveness Analysis for Regulation.
Committee to Evaluate Measures of Health Benefits for Environmental, Health, and Safety Regulation (Lawrence
RS, chair), Board on Health Care Services, Institute of Medicine, National Academy Press, Washington D.C., 2006.
66 U.S. Environmental Protection Agency. June 2005. Regulatory Impact Analysis for the Final Clean Air Visibility
Rule or the Guidelines for Best Available Retrofit Technology (BART) Determinations Under the Regional Haze
Regulations. Prepared by: Office of Air and Radiation. Available at
http://www.epa.gov/visibilirv/pdfs/bart ria 2005 6 15.pdf. Accessed December 15, 2005.
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Economic Impact Analysis
CHAPTER 9: Economic Impact Analysis
We prepared a draft Economic Impact Analysis (EIA) to estimate the economic impacts
of the proposed emission control program on the Small SI and Marine SI engine and equipment
markets. In this chapter we describe the Economic Impact Model (EIM) developed to estimate
the market-level changes in price and outputs for affected markets and the social costs of the
program as well as the expected distribution of those costs across affected economic sectors. We
also present the results of our analysis.
We estimate the net social costs of the proposed program to be about $241 million in
2030.l'2 This estimate reflects the estimated compliance costs associated with the Small SI and
Marine SI engine standards and the expected fuel savings from improved evaporative controls.
When the fuel savings are not taken into account, the results of the economic impact modeling
suggest that the social costs of these programs are expected to be about $569 million in 2030.
Consumers of Small SI and Marine products are expected to bear about 75 percent of these costs.
Small SI engine and equipment manufacturers are expected to bear 6 percent and 19 percent,
respectively. We estimate fuel savings of about $327 million in 2030, which will accrue to
consumers.
With regard to market-level impacts in 2030, the average price increase for Small SI
engines is expected to be about 9.1 percent ($17 per unit). The average price increase for Marine
SI engines is expected to be about 1.7 percent ($195 per unit). The largest average price increase
for Small SI equipment is expected to be about 5.6 percent ($15 per unit) for Class I equipment.
The largest average price increase for Marine SI vessels is expected to be about 2.1 percent
($178 per unit) for Personal Watercraft.
9.1 Overview and Results
9.1.1 What is an Economic Impact Analysis?
An Economic Impact Analysis (EIA) is prepared to inform decision makers about the
potential economic consequences of a regulatory action. The analysis consists of estimating the
social costs of a regulatory program and the distribution of these costs across stakeholders.
These estimated social costs can then be compared with estimated social benefits (as presented in
Chapter 8). As defined in EPA's Guidelines for Preparing Economic Analyses (EPA 2000, p
'All estimates presented in this section are in 2005$.
2This analysis is based on an earlier version of the engineering costs developed for this rule. The net
present value of the engineering costs used in this analysis (without taking the fuel savings into account, at a 3
percent discount rate over the period of the analysis) is $10.0 billion, which is about $100 million less than the net
present value of the final estimated engineering costs, $10.1 billion. We do not expect that a difference of this
magnitude would change the overall results of this economic impact analysis, in terms of market impacts and how
the costs are expected to be shared among stakeholders.
9-1
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Draft Regulatory Impact Analysis
113), social costs are the value of the goods and services lost by society resulting from a) the use
of resources to comply with and implement a regulation and b) reductions in output. In this
analysis, social costs are explored in two steps. In the market analysis, we estimate how prices
and quantities of goods affected by the proposed emission control program can be expected to
change once the program goes into effect. In the economic welfare analysis, we look at the total
social costs associated with the program and their distribution across stakeholders.
9.1.2 What Methodology Did EPA Use in this Economic Impact Assessment?
The Economic Impact Model (EIM) is a behavioral model developed for this proposal to
estimate price and quantity changes and total social costs associated with the emission controls
under consideration. The model relies on basic microeconomic theory to simulate how
producers and consumers of affected products can be expected to respond to an increase in
production costs as a result of the proposed emission control program. The economic theory that
underlies the model is described in detail in Section 9.2.
The EIM is designed to estimate the economic impacts of the proposed program by
simulating economic behavior. This is done by creating a model of the initial, pre-control
market for a product, shocking it by the estimated compliance costs, and observing the impacts
on the market. At the initial, pre-control market equilibrium, a market is characterized by a price
and quantity combination at which consumers are willing to purchase the same amount of a
product that producers are willing to produce at that price (demand is equal to supply). The
control program under consideration would increase the production costs of affected goods by
the amount of the compliance costs. This generates a "shock" to the initial equilibrium market
conditions. Producers of affected products will try to pass some or all of the increased costs on
to the consumers of these goods through price increases. In response to the price increases,
consumers will decrease their demand for the affected goods. Producers will react to the
decrease in quantity demanded by decreasing the quantity they produce; the market will react by
setting a higher price for those fewer units. These interactions continue until a new market
equilibrium price and quantity combination is achieved. The amount of the compliance costs
that can be passed on to consumers is ultimately limited by the price sensitivity of purchasers
and producers in the relevant market (price elasticity of demand and supply). The EIM explicitly
models these behavioral responses and estimates new equilibrium prices and output and the
resulting distribution of social costs across these stakeholders (producers and consumers).
The EIM is a behavioral model. The estimated social costs of this emission control
program are a function of the ways in which producers and consumers of the engines and
equipment affected by the standards change their behavior in response to the costs incurred in
complying with the standards. These behavioral responses are incorporated in the EIM through
the price elasticity of supply and demand (reflected in the slope of the supply and demand
curves), which measure the price sensitivity of consumers and producers. An "inelastic" price
elasticity (less than one) means that supply or demand is not very responsive to price changes (a
one percent change in price leads to less than one percent change in demand). An "elastic" price
elasticity (more than one) means that supply or demand is sensitive to price changes (a one
percent change in price leads to more than one percent change in demand). A price elasticity of
9-2
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Economic Impact Analysis
one is unit elastic, meaning there is a one-to-one correspondence between a change in price and
change in demand. The price elasticities used in this analysis are described in Section 9.3
andwere estimated using well-established econometric methods. It should be noted that demand
in the engine markets is internally derived from the Small SI equipment and Marine SI vessel
markets as part of the process of running the model. This is an important feature of the EIM,
which allows it to link the engine and equipment components of each model and simulate how
compliance costs can be expected to ripple through the affected market.
9.1.3 What Economic Sectors are Included in the Economic Impact Model?
There are two broad economic sectors affected by the emission control program
described in this proposal: (1) Small SI engines and equipment, and (2) Marine SI engines and
equipment. For Small SI engines and equipment we model one integrated handheld engine and
equipment category. On the nonhandheld side, the model distinguishes between 6 engine
categories, depending on engine class and useful life (Class I: UL125, UL250, and UL500;
Class II: UL250, UL500, UL1000), and 8 nonhandheld equipment categories
(agriculture/construction/ general industrial; utility and recreational vehicles; lawn mowers;
tractors; other lawn and garden; gensets/welders; pumps/compressors/pressure washers; and
snowblowers). For Marine SI engines and equipment, the model distinguishes between
sterndrives and inboards (SD/I), outboards (OB), and personal watercraft (PWC); SD/I and OB
are further classified by whether they are luxury or not. These markets are described in Section
9.3 and in more detail in the industry characterizations prepared for this proposal.
This analysis assumes that the all of these products are purchased and used by residential
households. This means that to model the behavior change associated with proposed standards
we model all uses as residential lawn and garden care, power generation (Small SI) or personal
recreation (Marine SI). We do not explicitly model commercial uses (how the costs of
complying with the proposed programs may affect the production of goods and services that use
Small SI or Marine SI engines or equipment as production inputs); we treat all commercial uses
as if they were residential uses. We believe this approach is reasonable because the commercial
share of the end use markets for both Small SI and Marine SI equipment is very small (see
Section 9.3.1.1). In addition, for any commercial uses of these products the share of the cost of
these products to total production costs is also small (e.g., the cost of a Small SI generator is only
a very small part of the total production costs for a construction firm). Therefore, a price
increase of the magnitude anticipated for this control program is not expected to have a
noticeable impact on prices or quantities of goods or services produced using Small SI or Marine
SI equipment as inputs (e.g., commercial turf care, construction, or fishing).
In the ELM the Small SI and Marine SI markets are not linked (there is no feedback
mechanism between the Small SI and Marine SI market segments). This is appropriate because
the affected equipment is not interchangeable and because there is very little overlap between the
engine producers in each market. These two sectors represent different aspects of economic
activity (lawn and garden care and power generation as opposed to recreational marine) and
production and consumption of one product is not affected by the other. In other words, an
increase in the price of lawnmowers is not expected to have an impact on the production and
9-3
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Draft Regulatory Impact Analysis
supply of personal watercraft, and vice versa. Production and consumption of each of these
products are the results of other factors that have little crossover impacts (the need for residential
garden upkeep or power generation; the desire for personal recreation).
Consistent with the proposed emission controls, this Economic Impact Analysis covers
engines sold in 49 states. California engines are not included because California has its own
state-level controls for Small SI and Marine SI engines. The sole exceptions are Small SI
engines used in agriculture and construction applications in California: these engines are
included in the control program of this analysis because the Clean Air Act preempts California
from setting standards for those engines.
Table 9.1-1 summarizes the markets included in this Economic Impact Analysis. More
detailed information on the markets and model data inputs is provided in Section 9.3.3, and in
the industry profiles prepared for this proposal (See Chapter 1, & RTI, 2006 ).
In the ELM, the Small SI and Marine SI markets are not linked (there is no feedback
mechanism between the Small SI and Marine SI market segments). This is appropriate because
the affected equipment is not interchangeable and because there is very little overlap between the
engine producers in each market. These two sectors represent different aspects of economic
activity (lawn and garden care and power generation as opposed to recreational marine) and
production and consumption of one product is not affected by the other. In other words, an
increase in the price of lawnmowers is not expected to have an impact on the production and
supply of personal watercraft, and vice versa. Production and consumption of each of these
productions are the results of other factors that have little cross-over impacts (the need for
residential garden upkeep or power generation; the desire for personal recreation).
9-4
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Economic Impact Analysis
Table 9.1-1: Summary of Markets in Economic Impact Model
Model Dimension
Small SI
Marine SI
Description of Markets
HANDHELD
No distinction between engine and
equipment types for this analysis
NONHANDHELD
Engine types
Class I (125, 250, 500 hours)
Class II (250, 500, 1000 hours)
Equipment types
Lawn mowers
Lawn and garden tractors
Pumps/compressors/pressure washers
Agriculture/construction/industrial
Other lawn and garden
Gensets/welders
Snowblowers
Utility and recreational vehicles
Engine and equipment types
SD/I recreational (runabouts,
airboats, jetboats)
SD/I luxury (yachts, cruisers, offshore)
OB recreational (runabouts, pontoons,
fishing)
OB luxury (yacht, cruiser, express
fish)
Personal watercraft (PWC)
Engine sizes
Less than 25 hp
26 to 50 hp
51 to 100 hp
101 to 175 hp
176 to 300 hp
Greater than 3 00 hp
Geographic scope
49 state, plus agriculture and
construction for California
49 state
(no California engines or equipment)
Market structure
Perfectly competitive
Perfectly competitive
Baseline population
EPA certification database
PSR OE Link sales database
EPA and CARB certification database
NMMA published statistical data
Growth projections
EPA's 2005 Nonroad model
EPA's 2005 Nonroad model
Supply elasticity
Econometric estimate (elastic)
Econometric estimate (elastic)
Demand elasticity
Econometric estimate
Gensets, all handheld: elastic
Lawn mowers: inelastic
All others: unit elastic
Econometric estimate (elastic)
Regulatory shock
Handheld (integrated market): direct
compliance costs (fixed + variable)
cause shift in supply function
Nonhandheld:
Engine: direct compliance costs
cause shift in supply function
Equipment (Class I): no direct
compliance costs but higher engine
prices cause shift in supply function
Equipment (Class II): direct
compliance costs plus higher engine
prices cause shift in supply function
PWC (integrated): direct compliance
costs (fixed + variable) cause shift in
supply function
SD/I and Outboard luxury:
Engine: direct compliance costs
cause shift in supply function
Vessel: direct compliance costs plus
higher engine prices cause shift in
supply function
Outboard recreational:
Engine: direct compliance costs
cause shift in supply function
Vessel: direct compliance costs
cause shift in supply function
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Draft Regulatory Impact Analysis
9.1.4 Summary of Results
The EIA consists of two parts: a market analysis and welfare analysis. The market
analysis looks at expected changes in prices and quantities for affected products. The welfare
analysis looks at economic impacts in terms of annual and present value changes in social costs.
We performed a market analysis for all years and all engines and equipment markets. In
this section we present summarized results for selected markets and years. More detail can be
found in the appendices to this chapter and in the docket for this rule (Li, 2007). Also included
in Appendix 9H are sensitivity analyses for several key inputs.
In this analysis, initial market equilibrium conditions are shocked by the sum of fixed and
variable costs. For the market analysis, this leads to a small increase in estimated price impacts
for the years 2011 through 2016, the period during which fixed costs are recovered. The
increase is small because, for many elements of the program, annual per unit fixed costs are
smaller than annual per unit variable costs. For the welfare analysis, applying both fixed and
variable costs means that the burden of the social costs attributable to producers and consumers
remains fixed throughout the period of analysis. This is because producers pass the fixed costs
to consumers at the same rate as the variable costs instead of having to absorb them internally.
9.1.4.1 Market Analysis Results
In the market analysis, we estimate how prices and quantities of goods affected by the
proposed emission control program can be expected to change once the program goes into effect.
The analysis relies on the initial market equilibrium prices and quantities for each type of
equipment and the price elasticity of supply and demand. It predicts market reactions to the
increase in production costs due to the new compliance costs (variable and fixed). It should be
noted that this analysis does not allow any other factors of production to vary. In other words, it
does not consider that manufacturers may adjust their production processes or marketing
strategies in response to the control program. Also, as explained above, while the markets are
shocked by both fixed and variable costs, the market shock is not offset by fuel savings.
A summary of the estimated market impacts is presented in Table 9.1-2 for 2013, 2018,
and 2030. These years were chosen because 2013 is the year of highest compliance; after 2018,
the fixed costs are recovered and the market impacts reflect variable costs as well as growth in
equipment population; and 2030 illustrates the long-term impacts of the program.
Market level impacts are reported for the engine and equipment markets separately. This
is because the EIM is a two-level model that treats these markets separately. However, changes
in equipment prices and quantities are due to impacts of both direct equipment compliance costs
and indirect engine compliance costs that are passed through to the equipment market from the
engine market through higher engine prices.
The average market-level impacts presented in this section are designed to provide a
9-6
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Economic Impact Analysis
broad overview of the expected market impacts that is useful when considering the impacts of
the rule on the economy as a whole. The average price impacts are product-weighted averages
of the results for the individual engine and equipment categories included in that sub-sector (e.g.,
the estimated Marine SI engine price and quantity changes are weighted averages of the
estimated results for all of the Marine SI engine markets). The average quantity impacts are the
sum of the decrease in units produced units across sub-markets. Price increases and quantity
decreases for specific types of engines and equipment are likely to be different.
Although each of the affected equipment in this analysis generally require one engine
(the exception being Marine SI sterndrive/inboards), the estimated decrease in the number of
engines produced in Table 9.1-2 is less than the estimated decrease in the number of equipment
produced. At first glance, this result seems counterintuitive because it does not reflect the
approximate one-to-one correspondence between engines and equipment. This discrepancy
occurs because the engine market-level analysis examines only output changes for engines that
are produced by independent engine manufacturers and subsequently sold to independent
equipment manufacturers. Engines produced and consumed by vertically integrated
equipment/engine manufactures are not explicitly modeled. Therefore, the market-level analysis
only reflects engines sold on the "open market," and estimates of output changes for engines
consumed internally are not reflected in this number.3 Despite the fact that changes in
consumption of internally consumed engines in not directly reported in the market-level analysis
results, the costs associated with these engines are included in the market-level analysis (as
supply shift for the equipment markets). In addition, the cost and welfare analyses include the
compliance costs associated with internally consumed engines.
9.1.4.1.1 Marine SI Market Analysis
The average price increase for Marine SI engines in 2013, the high cost year, is estimated
to be about 2.3 percent, or $257. By 2018, this average price increase is expected to decline to
about 1.7 percent, or $196, and remain at that level for later years. The market impact analysis
predicts that with these increases in engine prices the expected average decrease in total sales in
2013 is about 2.0 percent, or 8,800 engines. This decreases to about 1.6 percent in 2018, or
about 7,000 engines.
On the vessel side, the average price change reflects the direct equipment compliance
costs plus the portion of the engine costs that are passed on to the equipment purchaser (via
higher engine prices). The average price increase in 2013 is expected to be about 1.3 percent, or
$232. By 2018, this average price increase is expected to decline to about 1 percent, or $178.
These price increases are expected to vary across vessel categories. The category with the
largest price increase in 2013 is expected to be personal watercraft engines, with an estimated
price increase of about 2.8 percent in 2013; this is expected to decrease to 2.1 percent in 2018.
3For example, PWC and handheld equipment producers generally integrate equipment and engine
manufacturing processes and are included in the EIM as one-level equipment markets. Since there is no engine
market for these engines, the EIM does not include PWC and handheld engine consumption changes in engine
market-level results.
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Draft Regulatory Impact Analysis
The smallest expected change in 2013 is expected to be for sterndrive/inboards and outboard
recreational vessels, which are expected to see price increases of about 0.7 percent. The market
impact analysis predicts that with these increases in vessel prices the expected average decrease
in quantity produced in 2013 is about 2.7 percent, or 11,000 vessels. This is expected to
decrease to about 2.0 percent in 2018, or about 8,600 vessels. The personal watercraft category
is expected to experience the largest decline in 2013, about 5.6 percent (4,800 vessels). The
smallest percentage decrease in production is expected for sterndrive/inboards at 1.4 percent
(1,300 vessels); the smallest absolute decrease in quantity is expected for outboard recreational
vessels, at 113 vessels (1.5 percent).
9.1.4.1.2 Small SI Market Analysis
The average price increase for Small SI engines in 2013, the high cost year, is estimated
to be about 11.7 percent, or $22. By 2018, this average price increase is expected to decline to
about 9.1 percent, or $17, and remain at that level for later years. The market impact analysis
predicts that with these increases in engine prices the expected average decrease in total sales in
2013 is expected to be about 2.3 percent, or 371,000 engines. This is expected to decrease to
about 1.7 percent in 2018, or about 299,000 engines.
On the equipment side, the average price change reflects the direct equipment compliance
costs plus the portion of the engine costs that are passed on to the equipment purchaser (via
higher engine prices). The average price increase for all Small SI equipment in 2013 is expected
to be about 3.1 percent, or $14. By 2018, this average price increase is expected to decline to
about 2.4 percent, or $10. The average price increase and quantity decrease differs by category
of equipment. As shown in Table XII.F-2, the price increase for Class I equipment is estimated
to be about 6.9 percent ($19) in 2013, decreasing to 5.5 percent ($15) in 2018. The market
impact analysis predicts that with these increases in equipment prices the expected average
decrease in the quantity of Class I equipment produced in 2013 is about 2.2 percent, or 219,400
units. This is expected to decrease to about 1.8 percent in 2018, or about 189,700 units. For
Class II equipment, a higher price increase is expected, about 3.9 percent ($41) in 2013,
decreasing to 2.6 percent ($25) in 2018. The expected average decrease in the quantity of Class
II equipment produced in 2013 is about 4.3 percent, or 157,300 units, decreasing to 2.8 percent,
or about 114,000 units, in 2018.
For the handheld equipment market, prices are expected to increase about 0.3 percent for
all years, and quantities are expected to decrease about 0.6 percent.
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Economic Impact Analysis
Table 9.1-2: Summary of Estimated Market Impacts for 2013, 2018, 2030 (2005$)
Market
Change
Absolute
in Price
Percent
Change
Absolute
in Quantity
Percent
2013
Marine
Engines
Equipment
SD/I
OB Recreational
OB Luxury
PWC
Small SI
Engines
Equipment
Class I
Class II
HH
$257
$232
$252
$638
$206
$237
$22
$14
$19
$41
$0.3
2.3%
1.3%
0.7%
0.7%
1.1%
2.8%
11.7%
3.1%
6.9%
3.9%
0.3%
-8,846
-10,847
-1,336
-113
-4,579
-4,819
-371,097
-482,942
-219,400
-157,306
-106,236
-2.0%
-2.7%
-1.4%
-1.5%
-2.1%
-5.6%
-2.3%
-1.9%
-2.2%
-4.3%
-0.6%
2018
Marine
Engines
Equipment
SD/I
OB Recreational
OB Luxury
PWC
Small SI
Engines
Equipment
Class I
Class II
HH
$196
$178
$195
$496
$160
$178
$17
$10
$15
$25
$0.2
1.7%
1.0%
0.5%
0.6%
0.8%
2.1%
9.1%
2.4%
5.5%
2.6%
0.3%
-7,002
-8,563
-1,072
-91
-3,634
-3, 766
-298,988
-401,025
-189,771
-113,999
-97,255
-1.6%
-2.0%
-1.1%
-1.1%
-1.6%
-4.2%
-1.7%
-1.4%
-1.8%
-2.8%
-0.5%
2030
Marine
Engines
Equipment
SD/I
OB Recreational
OB Luxury
PWC
Small SI
Engines
Equipment
Class I
Class II
HH
$195
$179
$195
$496
$160
$178
$17
$10
$15
$25
tfrt •>.
1.7%
1.0%
0.5%
0.6%
0.8%
2.1%
9.1%
2.4%
5.6%
2.6%
0 1%
-7,728
-9,333
-1,161
-98
-3,998
-4,076
-354,915
-475,825
-225,168
-135,400
-775 757
-1.6%
-2.0%
-1.1%
-1.1%
-1.7%
-4.2%
-1.7%
-1.4%
-1.8%
-2.8%
-0 V/n
9-9
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Draft Regulatory Impact Analysis
9.1.4.2 Economic Welfare Results
In the economic welfare analysis we look at the costs to society of the proposed program
in terms of losses to consumer and producer surplus. These surplus losses are combined with
estimated fuel savings to estimate the net economic welfare impacts of the program. Estimated
annual net social costs for selected years are presented in Table 9.1-3. This table shows that total
social costs for each year are slightly less than the total engineering costs. This is because the
total engineering costs do not reflect the decreased sales of engines and equipment that are
incorporated in the total social costs.
9-10
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Economic Impact Analysis
Table 9.1-3: Estimated Annual Engineering and Social Costs Through 2038
(2005$, Smillion)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPVat3%a
NPV at 7%a
Total Net Engineering Net Social
Engineering Total Social . Costs Costs
Costs Costs (including fuel (including fuel
savings) savings)
$9.5
$171.7
$191.1
$470.5
$647.3
$652.5
$621.1
$627.0
$520.9
$492.6
$497.2
$503.6
$510.0
$516.4
$522.7
$529.1
$535.8
$542.3
$548.7
$555.2
$561.6
$568.0
$574.5
$580.9
$587.4
$593.8
$600.3
$606.7
$613.1
$619.6
$626.0
$9,996.2
S5 863 6
$9.5
$168.8
$188.0
$463.4
$638.2
$643.4
$613.1
$619.0
$515.2
$487.5
$492.0
$498.4
$504.7
$511.0
$517.3
$523.7
$530.3
$536.7
$543.1
$549.4
$555.8
$562.2
$568.6
$575.0
$581.3
$587.7
$594.1
$600.5
$606.9
$613.2
$619.6
$9,882.
$5794
$3.1
$13.7
$25.4
$64.9
$103.5
$136.5
$161.2
$182.3
$200.9
$216.2
$229.9
$242.1
$253.1
$263.3
$272.9
$281.4
$289.3
$296.6
$303.6
$310.1
$316.3
$322.0
$327.3
$332.3
$337.1
$341.7
$346.1
$350.4
$354.5
$358.5
$362.5
2 $4,356.
1 S9 991
$6.4
$157.9
$165.7
$405.7
$543.8
$516.0
$459.9
$444.7
$320.0
$276.4
$267.3
$261.5
$256.9
$253.1
$249.8
$247.7
$246.5
$245.6
$245.1
$245.1
$245.3
$246.1
$247.2
$248.6
$250.3
$252.1
$254.2
$256.3
$258.6
$261.1
$263.6
2 $5,640.1
5 S3 579 1
$6.4
$155.1
$162.6
$398.5
$534.7
$506.9
$451.9
$436.7
$314.2
$271.3
$262.1
$256.2
$251.6
$247.8
$244.4
$242.3
$241.0
$240.0
$239.5
$239.3
$239.5
$240.2
$241.3
$242.6
$244.2
$246.0
$248.0
$250.1
$252.3
$254.7
$257.1
$5,562.0
S3 509 6
aEPA EPA presents the present value of cost and benefits estimates using both a three percent and a seven
percent social discount rate. According to OMB Circular A-4, "the 3 percent discount rate represents the
'social rate of time preference'. . . [which] means the rate at which 'society' discounts future consumption flows
to their present value " ; "the seven percent rate is an estimate of the average before-tax rate of return to private
capital in the U.S. economy . . . [that] approximates the opportunity cost of capital."
9-11
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Draft Regulatory Impact Analysis
Figure 9.1-1: Estimated Engineering, Total Social, Net Social Costs and Fuel Savings
$700.0 n
$600.0
$500.0
| $400.0 -
1 $300.0
** $200.0
$100.0 -
$0.0
Total Engineering Costs
-Fuel Savings
Total Social Costs
Net Social Costs
Table 9.1-4 shows how total social costs are expected to be shared across stakeholders,
for selected years. According to these results, consumers in the Marine SI market are expected
to bear approximately 66 percent of the cost of the Marine SI program. This is expected to be
offset by the fuel savings. Vessel manufacturers are expected to bear about 22 percent of that
program, and engine manufacturers the remaining 11 percent. In the Small SI market,
consumers are expected to bear 79 percent of the cost of the Small SI program. This will also be
offset by the fuel savings. Equipment manufacturers are expected to bear about 17 percent of
that program, and engine manufacturers the remaining 4 percent. The estimated percentage
changes in surplus are the same for all years because the initial equilibrium conditions are
shocked by both fixed and variable costs; producers would pass the fixed costs to consumers at
the same rate as the variable costs.
9-12
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Economic Impact Analysis
Table 9.1-4: Summary of Estimated Social Costs for 2013, 2018, 2030 (2005$, Smillion)
Market
Absolute Change
in Surplus
Percent Change in
Surplus
Fuel
Savings
total Change in
Surplus
2013
Marine SI
Engine Manufacturers
Equipment Manufacturers
End User (Households)
Subtotal
Small SI
Engine Manufacturers
Equipment Manufacturers
End User (Households)
Subtotal
TOTAL
-$21.54
-$42.23
-$125.14
-$188.91
-$18.36
-$80.16
-$355.95
-$454.47
-$643.38
11%
22%
66%
4%
18%
78%
$42.27
$94.26
$136.53
-$21.54
-$42.23
-$82.87
-$146.64
-$18.36
-$80.16
-$261.69
-$360.21
-$506.85
2018
Marine SI
Engine Manufacturers
Equipment Manufacturers
End User (Households)
Subtotal
Small SI
Engine Manufacturers
Equipment Manufacturers
End User (Households)
Subtotal
TOTAL
-$17.29
-$34.02
-$100.19
-$151.50
-$13.89
-$57.65
-$268.95
-$340.49
-$491.99
11%
22%
66%
4%
17%
79%
$87.12
$142. 78
$229.90
-$17.29
-$34.02
-$13.07
-$64.38
-$13.89
-$57.65
-$126.17
-$197.71
-$262.09
2030
Marine SI
Engine Manufacturers
Equipment Manufacturers
End User (Households)
Subtotal
Small SI
Engine Manufacturers
Equipment Manufacturers
End User (Households)
Subtotal
TOTAT,
-$18.81
-$36.97
-$108.52
-$164.30
-$16.49
-$68.45
-$319.31
-$404.25
-«T/ffl ??
11%
23%
66%
4%
17%
79%
$149.36
$177.89
X17.7 ' ?.*
-$18.81
-$36.97
$40.84
-$14.94
-$16.49
-$68.45
-$141.42
-$226.36
-*?41 W
Table 9.1-5 contains more detailed information on the sources of the social costs for
2013. This table shows that vessel and equipment manufacturers are expected to bear more of
the burden of the program than engine manufacturers. On the marine side, the loss of producer
surplus for the vessel manufacturers has two sources. First, they would bear part of the burden
of the equipment costs. Second, they would also bear part of the engine costs, which are passed
on to vessel manufacturers in the form of higher engine prices. Vessel manufacturers would not
be able to pass along a greater share of the engine and vessel compliance costs to end consumers
due to the elastic price elasticity of demand for consumers of these vessels. On the Small SI
side, equipment manufacturers can pass on more of the compliance costs to end consumers
9-13
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Draft Regulatory Impact Analysis
because the price elasticity of demand in these markets is less elastic.
Table 9.1-5: Estimated Surplus Changes by Market and Stakeholder for 2013
(2005$, Smillion)
Scenario
Engine Manufacturers
Equipment Manufacturers
Engine Price Changes
Equipment Cost Changes
End User (Households)
Engine Price Changes
Equipment Price Changes
Subtotal
Engine Manufacturers
Equipment Manufacturers
Engine Price Changes
Equipment Cost Changes
End User (Households)
Engine Price Changes
Equipment Cost Changes
Subtotal
TOT AT,
Engineering
Compliance
Costs
$133.2
$59.1
$192.2
$371.9
$88.4
$460.3
$652.5
Producer
Surplus
Marine SI
-$21.5
-$42.2
-$18.7
-$23.6
-$63.8
Small SI
-$18.4
-$80.2
-$59.0
-$21.1
-$98.5
-S162.3
Consumer
Surplus
-$125.1
-$91.8
-$33.3
-$125.1
-$355.9
-$289.8
-$66.1
-$355.9
-X481.1
Total
Surplus
-$21.5
-$42.2
-$125.1
-$188.9
-$18.4
-$80.2
-$355.9
-$454.5
-S643.4
Fuel Net
Savings Surplus
-$21.5
-$42.2
$42.3 -$82.8
$42.3 -$146.6
-$18.4
-$80.2
$94.3 -$261.7
$94.3 -$360.2
$136.6 -$506.8
The present value of net social costs of the proposed standards through 2038 at a 3
percent discount rate, shown in Table XII.F-6, is estimated to be $5.5 billion, taking the fuel
savings into account. We also performed an analysis using a 7 percent social discount rate.
Using that discount rate, the present value of the net social costs through 2038 is estimated to be
$3.5 billion, including the fuel savings.
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Economic Impact Analysis
Table 9.1-6. Estimated Net Social Costs Through 2038 by Stakeholder (2005$, Smillion)
Total Change in Percentage Change Net Change in
Market Surplus in Total Surplus Fuel Savings Surplus
Marine SI
Engine Manufacturers
Equipment Manufacturers
End User (Households)
Subtotal
Small SI
Engine Manufacturers
Equipment Manufacturers
End User (Households)
Subtotal
TOTAL
Marine SI
Engine Manufacturers
Equipment Manufacturers
End User (Households)
Subtotal
Small SI
Engine Manufacturers
Equipment Manufacturers
End User (Households)
Subtotal
TOTAT,
Net Present Value 3%
-$354.4
-$688.8
-$2,058.8
-$3,102.0
-$275.0
-$1,171.8
-$5,333.4
-$6,780.2
-$9,882.2
Net Present Value 7%
-$216.4
-$417.6
-$1,259.9
-$1,893.8
-$157.8
-$680.4
-$3,062.1
-$3,900.3
-$5.794.2
11%
22%
66%
4%
17%
79%
11%
22%
66%
4%
17%
79%
$1,831.3
$1,831.3
$2,524.8
$2,524.8
$4,356.1
$937.1
$937.1
$1,354.4
$1,354.4
$2.291.5
-$354.4
-$688.8
-$227.5
-$1,270.7
-$275.0
-$1,171.8
-$2,808.6
-$4,255.4
-$5,526.1
-$216.4
-$471.6
-$322.8
-$956.8
-$157.8
-$680.4
-$1,707.7
-$2,545.9
-$3.502.6
9-15
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Draft Regulatory Impact Analysis
9.2 Economic Methodology
Economic impact analysis uses a combination of theory and econometric modeling to
evaluate potential behavior changes associated with a new regulatory program. As noted above,
the goal is to estimate the impact of the regulatory program on producers and consumers. This is
done by creating a mathematical model based on economic theory and populating the model
using publically available price and quantity data. A key factor in this type of analysis is the
responsiveness of the quantity of engines and equipment demanded by consumers or supplied by
producers to a change in the price of that product. This relationship is called the elasticity of
demand or supply.
The EIM's methodology is rooted in applied microeconomic theory and was developed
following the OAQPS Economic Analysis Resource Document (EPA 1999). This section
discusses the economic theory underlying the modeling for this EIA and several key issues that
affect the way the model was developed.
9.2.1 Behavioral Economic Models
Models incorporating different levels of economic decision making can generally be
categorized as w/Y/z-behavior responses or without-bohavior responses. The EIM is a behavioral
model.
Engineering cost analysis is an example of the latter and provides detailed estimates of
the cost of a regulation based on the projected number of affected units and engineering
estimates of the annualized costs. The result is an estimate of the total compliance costs for a
program. However, these models do not attempt to estimate how a regulatory program will
change the prices or output of an affected industry. Therefore, the results may over-estimate the
total costs of a program because they do not take decreases in quantity produced into account.
The w/Y/7-behavior response approach builds on the engineering cost analysis and
incorporates economic theory related to producer and consumer behavior to estimate changes in
market conditions. As Bingham and Fox (1999) note, this framework provides "a richer story"
of the expected distribution of economic welfare changes across producers and consumers. In
behavioral models, manufacturers of goods affected by a regulation are economic agents that can
make adjustments, such as changing production rates or altering input mixes, that will generally
affect the market environment in which they operate. As producers change their production
levels in response to a new regulation, consumers of the affected goods are typically faced with
changes in prices that cause them to alter the quantity that they are willing to purchase. These
changes in price and output resulting from the market adjustments are used to estimate the
distribution of social costs between consumers and producers.
If markets are competitive and per-unit regulatory costs are small, the behavioral
approach will yield approximately the same total cost impact as the engineering cost approach.
However, the advantage of the w/Y/z-behavior response approach is that it illustrate how the costs
9-16
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Economic Impact Analysis
flow through the economic system and it identifies which stakeholders, producers, and
consumers are most likely to be affected.
9.2.2 What Is the Economic Theory Underlying the EIM?
The EIM is a multi-market partial-equilibrium numerical simulation model that estimates
price and quantity changes in the intermediate run under competitive market conditions. Each of
these model features is described in this section.
9.2.2.1 Partial Equilibrium Multi-Market Model
In the broadest sense, all markets are directly or indirectly linked in the economy, and a
new regulatory program will theoretically affect all commodities and markets to some extent.
However, not all regulatory programs have noticeable impacts on all markets. For example, a
regulation that imposes significant per unit compliance costs on an important manufacturing
input, such as steel, will have a larger impact on the national economy. A regulation that
imposes a small direct compliance cost on an important input, or any direct compliance costs on
an input that is only a small share of production costs, would be expected to have less of an
impact on all markets in the economy.
The appropriate level of market interactions to be included in an economic impact
analysis is determined by the number of industries directly affected by the requirements and the
ability of affected firms to pass along the regulatory costs in the form of higher prices. There are
at least three alternative approaches for modeling interactions between economic sectors, that
reflect three different levels of analysis.
In ^partial equilibrium model, individual markets are modeled in isolation. The only
factor affecting the market is the cost of the regulation on facilities in the industry being
modeled; there are no interaction effects with other markets. Conditions in other markets are
assumed either to be unaffected by a policy or unimportant for cost estimation.
In a multi-market model, a subset of related markets is modeled together, with sector
linkages, and hence selected interaction effects, explicitly specified. This approach represents an
intermediate step between a simple, single-market partial equilibrium approach and a full general
equilibrium approach. This technique has most recently been referred to in the literature as
"partial equilibrium analysis of multiple markets" (Berck and Hoffmann, 2002).
In a general equilibrium model, all sectors of the economy are modeled together,
incorporating interaction effects between all sectors included in the model. General equilibrium
models operationalize neoclassical microeconomic theory by modeling not only the direct effects
of control costs but also potential input substitution effects, changes in production levels
associated with changes in market prices across all sectors, and the associated changes in welfare
economy-wide. A disadvantage of general equilibrium modeling is that substantial time and
resources are required to develop a new model or tailor an existing model for analyzing
regulatory alternatives.
9-17
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Draft Regulatory Impact Analysis
This analysis uses a partial equilibrium approach in that it models only those markets that
are directly affected by the proposed emission control program: the Small SI and Marine SI
markets. In addition, these markets are modeled separately. This approach is appropriate
because the Small SI and Marine SI sector represent different activities (residential garden care
and personal recreation), and production and consumption of one is not affected by the other. In
other words, an increase in the price of lawnmowers is not expected to have an impact on the
production and supply of recreational marine vessels, and vice versa. Production and
consumption of these products are the result of other factors that have little cross-over impacts.
The EIM uses a single-market approach for some sectors (Small SI handheld, Class I
nonhandheld, personal watercraft, outboards recreational) and a two-market approach for the
others (Small SI Class II nonhandheld; sterndrive/inboards; and outboards luxury) reflecting
whether the markets are integrated and whether the controls affect only engines or both engines
and equipment. The advantage of a two-market approach is that it allows us to describe the
expected distribution of the program's effects across equipment and engine markets as well as
the effects on purchasers of these engines and equipment. To simulate these relationships, the
ELM consists of a series of standard partial equilibrium models that are linked through
interactions between the equipment and engine markets. As a result, the model estimates
changes in prices and quantities across all markets simultaneously for each of the linked engine
and equipment markets.
The EIM does not specifically estimate potential price and quantity impacts on final
goods and services that may be produced by equipment that would be subject to the proposed
controls in the agricultural and construction sectors. This is appropriate because the vast
majority of engines and equipment that would be subject to the proposed standards are purchased
for residential use (recreational marine; home lawn and garden and residential utility uses; see
Section 9.3 and the industry characterization prepared for this rule). Not only is the share of
commercial users of this equipment small, but such equipment represents only a small portion of
the total production costs for application markets such as agriculture, construction or
manufacturing. The proposed standards would affect only a very small part of total inputs for
those markets and would not be expected to result in an adverse impact on output and prices of
goods produced in these commercial application sectors.
It should also be noted that the economic impact model employed for this analysis
estimates the market-level economic impacts of the rule. It is not a firm-level analysis and
therefore the impact for any particular manufacturer may be greater or less than the average
impact for the market as a whole. This difference can be important, particularly where the rule
affects different firms' costs over different volumes of production. However, to the extent there
are differential effects, EPA believes that the wide array of flexibilities provided in this rule are
adequate to address any cost inequities that are likely to arise.
9.2.2.2 Perfect Competition Model
For all markets that are modeled, the analyst must characterize the degree of competition
within each market. The discussion generally focuses on perfect competition (price-taking
9-18
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Economic Impact Analysis
behavior) versus imperfect competition (the lack of price-taking behavior). This EIM is abased
on an assumption of perfect competition. This means that consumers and firms are price takers
and do not have the ability to influence market prices.
In a perfectly competitive market at equilibrium the market price equals the value society
(consumers) places on the marginal product, as well as the marginal cost to society (producers).
Producers are price takers, in that they respond to the value that consumers put on the product. It
should be noted that the perfect competition assumption is not primarily about the number of
firms in a market. It is about how the market operates: whether or not individual firms have
sufficient market power to influence the market price. Indicators that allow us to assume perfect
competition include absence of barriers to entry, absence of strategic behavior among firms in
the market, and product differentiation.4 Finally, according to contestable market theory,
oligopolies and even monopolies will behave very much like firms in a competitive market if it
is possible to enter particular markets costlessly (i.e., there are no sunk costs associated with
market entry or exit). This would be the case, for example, when products are substantially
similar.
In contrast, imperfect competition implies firms have some ability to influence the market
price of output they produce. One of the classic reasons firms may be able to do this is their
ability to produce commodities with unique attributes that differentiate them from competitors'
products. This allows them to limit supply, which in turn increases the market price, given the
traditional downward-sloping demand curve. Decreasing the quantity produced increases the
monopolist's profits but decreases total social surplus because a less than optimal amount of the
product is being consumed. In the monopolistic equilibrium, the value society (consumers)
places on the marginal product exceeds the marginal cost to society (producers) of producing the
last unit. Thus, social welfare would be increased by inducing the monopolist to increase
production. Social cost estimates associated with a proposed regulation are larger with
monopolistic market structures and other forms of imperfect competition because the regulation
exacerbates the existing social inefficiency of too little output from a social perspective. The
Office of Management and Budget (OMB) explicitly mentions the need to consider these market
power-related welfare costs in evaluating regulations under Executive Order 12866 (OMB,
1996).
Perfect competition is a widely accepted economic practice for this type of analysis and
only in rare cases are other approaches used (EPA 2000, p. 126). For the markets under
consideration in this EIA, we assume the perfectly competitive market structure. This is because
these markets do not exhibit evidence of noncompetitive behavior: there are no indications of
barriers to entry, the firms in these markets are not price setters, and there is no evidence of high
levels of strategic behavior in the price and quantity decisions of the firms.
4The number of firms in a market is not a necessary condition for a perfectly competitive market. See
Robert H. Frank, Microeconomics and Behavior, 1991, McGraw-Hill, Incl., p. 33.
9-19
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Draft Regulatory Impact Analysis
As described in the industry profiles for this proposed regulation (RTI, 2004), several of
the recreational marine and Small SI sectors are highly concentrated and thus have the potential
for the emergence of imperfect competition and price-setting behavior. Nonetheless, our
analysis suggests that mitigating factors will limit this potential for raising price above marginal
cost and thus that the assumption of perfect competition is justified. Among the mitigating
factors are the presence of substantial import competition, relative ease of entry, existing excess
production capacity, and a historical tendency of market participants to compete on price. These
markets are also mature markets, as evidenced by unit sales growing at the rate of population
increases. Pricing power in such markets is typically limited, and empirical data indicates that
price pressure has existed in these markets for years and firms in these markets are price takers.5
In addition, the products produced within each market are somewhat homogeneous in that
engines and equipment from one firm can be purchased instead of engines and equipment from
another firm, enhancing competition.
According to contestable market theory, oligopolies and even monopolies will behave
very much like firms in a competitive market if it is possible to enter particular markets
costlessly (i.e., there are no sunk costs associated with market entry or exit). This is the case
with these markets as there is significant excess production capacity in both the Small SI and
Marine SI industries, in part due to improved productivity and efficiency in current plants. Data
on domestic plant capacity utilization rates are published by the U.S. Census (U.S. Census,
2005). The full production capability is defined as "the maximum level of production that an
establishment could reasonably expect to attain under normal and realistic operating conditions
fully utilizing the machinery and equipment in place." Recent domestic data for 2000 to 2004
indicate the internal combustion engine industry (NAICS 333618 Other Equipment
Manufacturing) operated at 53 to 73 percent of full production capability. Similar data for
vessels (NAICS 336612 Boat Building) indicate this industry operated between 59 and 62
percent of full production capability. The small SI equipment industry (NAICS 333112, lawn &
garden tractor and home & lawn garden equipment manufacturing) operated at 50 to 65 percent
of full production capability. Idle production capacity also limits the ability of firms to raise
prices, since competitors can easily capture market share by increasing their production at the
expense of a producer that increases its prices.
Finally, domestic producers face substantial competition from foreign manufacturers
(RTI, 2006). These overseas firms may have strong incentives to compete vigorously on price
with the well-established U.S. firms. For all of these reasons it is appropriate to use a perfect
competition model to estimate the economic impacts of this proposal.
9.2.2.3 Intermediate-Run Model
In developing the multi-market partial equilibrium model, the choices available to
producers must be considered. For example, are producers able to increase their factors of
5 RTI (2006). Historical Market Data and Trends, Industry Profile for Small SI Engines and Equipment,
Section 2.5. Draft Report
9-20
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Economic Impact Analysis
production (e.g., increase production capacity) or alter their production mix (e.g., substitution
between materials, labor, and capital)? These modeling issues are largely dependent on the time
horizon for which the analysis is performed. Three benchmark time horizons are discussed
below: the very short run, the long run, and the intermediate run. This discussion relies in large
part on the material contained in the OAQPSEconomic Analysis Resource Guide (U.S. EPA,
1999).
The EIM models market impacts in the intermediate run. The use of the intermediate run
means that some factors of production are fixed and some are variable. This modeling period
allows analysis of the economic effects of the rule's compliance costs on current producers. As
described below, a short-run analysis imposes all compliance costs on producers, while a
long-run analysis imposes all costs on consumers. The use of the intermediate time frame is
consistent with economic practices for this type of analysis.
In the very short run, all factors of production are assumed to be fixed, leaving the
directly affected entity with no means to respond to increased costs associated with the
regulation (e.g., they cannot adjust labor or capital inputs). Within a very short time horizon,
regulated producers are constrained in their ability to adjust inputs or outputs due to contractual,
institutional, or other factors and can be represented by a vertical supply curve, as shown in
Figure 9.2-1. In essence, this is equivalent to the nonbehavioral model described earlier.
Neither the price nor quantity changes and the manufacturer's compliance costs become fixed or
sunk costs. Under this time horizon, the impacts of the regulation fall entirely on the regulated
entity. Producers incur the entire regulatory burden as a one-to-one reduction in their profit.
This is referred to as the "full-cost absorption" scenario and is equivalent to the engineering cost
estimates. Although there is no hard and fast rule for determining what length of time
constitutes the very short run, it is inappropriate to use this time horizon for this analysis because
it assumes economic entities have no flexibility to adjust factors of production.
9-21
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Draft Regulatory Impact Analysis
Figure 9.2-1: Short Run: All Costs Born by Producers
Price
Output
In the long run, all factors of production are variable, and producers can be expected to
adjust production plans in response to cost changes imposed by a regulation (e.g., using a
different labor/capital mix). Figure 9.2-2 illustrates a typical, if somewhat simplified, long-run
industry supply function. The function is horizontal, indicating that the marginal and average
costs of production are constant with respect to output.6 This horizontal slope reflects the fact
that, under long-run constant returns to scale, technology and input prices ultimately determine
the market price, not the level of output in the market.
Market demand is represented by the standard downward-sloping curve. The market is
assumed here to be perfectly competitive; equilibrium is determined by the intersection of the
supply and demand curves. In this case, the upward shift in the market supply curve represents
the regulation's effect on production costs. The shift causes the market price to increase by the
full amount of the per-unit control cost (i.e., from P to P'). With the quantity demanded sensitive
to price, the increase in market price leads to a reduction in output in the new with-regulation
equilibrium (i.e., Q to Q'). As a result, consumers incur the entire regulatory burden as
represented by the loss in consumer surplus (i.e., the area P ac P'). In the nomenclature of EIAs,
this long-run scenario is typically referred to as "full-cost pass-through" and is illustrated in
Figure 9.2-2.
6 The constancy of marginal costs reflects an underlying assumption of constant returns to scale of
production, which may or may not apply in all cases.
9-22
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Economic Impact Analysis
Figure 9.2-2: Long Run: Full-Cost Pass-Through
With Regulation
y Without Regulation
Output
Taken together, impacts modeled under the long-run/full-cost-pass-through scenario
reveal an important point: under fairly general economic conditions, a regulation's impact on
producers is transitory. Ultimately, the costs are passed on to consumers in the form of higher
prices. However, this does not mean that the impacts of a regulation will have no impact on
producers of goods and services affected by a regulation. For example, the long run may cover
the time taken to retire all of today's capital vintage, which could take decades. Therefore,
transitory impacts could be protracted and could dominate long-run impacts in terms of present
value. In addition, to evaluate impacts on current producers, the long-run approach is not
appropriate. Consequently a time horizon that falls between the very
short-run/full-cost-absorption case and the long-run/full-cost-pass-through case is most
appropriate for this El A.
The intermediate run time frame allows examination of impacts of a regulatory program
during the transition between the short run and the long run. In the intermediate run, some
factors are fixed; some are variable. In other words, producers can adjust some, but not all,
factors of production, meaning they will bear some portion of the costs of the regulatory
program. The existence of fixed production factors generally leads to diminishing returns to
those fixed factors. This typically manifests itself in the form of a marginal cost (supply)
function that rises with the output rate, as shown in Figure 9.2-3.
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Draft Regulatory Impact Analysis
Figure 9.2-3: Intermediate Run: Partial-Cost Pass-Through
Price
Increase
With Regulation
Unit Cost Increase
Without Regulation
Output
Again, the regulation causes an upward shift in the supply function. The lack of resource
mobility may cause producers to suffer profit (producer surplus) losses in the face of regulation;
however, producers are able to pass through some of the associated costs to consumers, to the
extent the market will allow. As shown, in this case, the market-clearing process generates an
increase in price (from P to P') that is less than the per-unit increase in costs, so that the
regulatory burden is shared by producers (net reduction in profits) and consumers (rise in price).
In other words, there is a loss of both producer and consumer surplus.
Consistent with other economic impact analyses performed by EPA, this EIM uses an
intermediate run approach. This approach allows us to examine the market and social welfare
impacts of the program as producers adjust their output and consumers adjust their consumption
of affected products in response to the increased production costs. During this period, the
distribution of the welfare losses between producer and consumer depends in large part on the
relative supply and demand elasticity parameters used in the model. For example, if demand for
Small SI equipment is relatively inelastic (i.e., demand does not decrease much as price
increases), then most of the direct compliance cost on refiners will be passed along to Small SI
equipment consumers in the form of higher prices.
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Economic Impact Analysis
9.2.3 How is the EIM Used to Estimate Economic Impacts?
9.2.3.1 Estimation of Market Impacts (Single Market)
A graphical representation of a general economic competitive model of price formation,
as shown in Figure 9.2-4(a), posits that market prices and quantities are determined by the
intersection of the market supply and market demand curves. Under the baseline scenario, a
market price and quantity (p,Q) are determined by the intersection of the downward-sloping
market demand curve (DM) and the upward-sloping market supply curve (SM). The market
supply curve reflects the sum of the domestic (Sd) and import (S;) supply curves.
Figure 9.2-4: Market Equilibrium without and with Regulation
= P
Q
Domestic Supply
Foreign Supply
Market
a) Baseline Equilibrium
P'
P
S'.
J I
Q' Q
Domestic Supply
Foreign Supply
Market
b) With-Regulation Equilibrium
With the regulation, the costs of production increase for suppliers. The imposition of
these regulatory control costs is represented as an upward shift in the supply curve for domestic
and import supply by the estimated compliance costs. As a result of the upward shift in the
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supply curve, the market supply curve will also shift upward as shown in Figure 9.2-3(b) to
reflect the increased costs of production.
At baseline without the proposed rule, the industry produces total output, Q, at price, p,
with domestic producers supplying the amount qd and imports accounting for Q minus qd, or qf.
With the regulation, the market price increases from p to p', and market output (as determined
from the market demand curve) decreases from Q to Q'. This reduction in market output is the
net result of reductions in domestic and import supply.
As indicated in Figure 9.2-4, when the proposed standards are applied the supply curve
will shift upward by the amount of the estimated compliance costs. The demand curve, however,
does not shift in this analysis. This is explained by the dynamics underlying the demand curve.
The demand curve represents the relationship between prices and quantity demanded. Changes
in prices lead to changes in the quantity demanded and are illustrated by movements along a
fixed demand curve. In contrast, changes in any of the other variables would lead to change in
demand and are illustrated as shifts in the position of the demand curve.7 For example, an
increase in the number of consumers in a market would cause the demand curve to shift outward
because there are more individuals willing to buy the good at every price. Similarly, an
exogenous increase in nominal income would also lead the demand curve to shift outward as
people choose to buy more of a good at a given price. Changes in the prices of related good and
tastes or preferences can also lead to demand curve shifts.
The proposed standards are expected to increase the costs of production in the Small SI
engine and equipment and Marine SI engine vessel markets and ultimately lead to higher
equilibrium prices in the affected markets. As these prices increase, the quantity demanded falls
(i.e., the price change leads to a movement along the demand curve).8 However, the proposed
program is not expected to lead to shifts in the demand curve for several reasons. First, the
assume the program will not directly influence prices of related goods (i.e., prices of any
potential substitutes remain constant in the analysis). In addition, the program will not change
nominal incomes through public finance mechanisms (e.g., lump sum subsidies/taxes) or change
labor supply decisions. Finally, we assume tastes and preference will not change during the
period of analysis. For all of these reasons, it would be inappropriate to shift the demand curve
for this analysis.
7 An accessible detailed discussion of these concepts can be found in Chapter 5-7 of Nicholson's (1998)
intermediate microeconomics textbook.
8 Nicholson (1998) provides an example of the effects of a price increase on the quantity consumed (p: 134-
135). Throughout this discussion, we use uncompensated Marshallian demand functions. As a result, a price
increase will also change an individual's "real" income and reinforce substitution quantity responses to a good's
price change through an "income" effect. Both substitution and (real) income effects are therefore built in the
Marshallian demand function used for this analysis. It is important to note, however, that this type of "income"
effect is conceptually different from an exogenous change in nominal income that leads to a shift in a demand
function.
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Economic Impact Analysis
9.2.3.2 Incorporating Multi-Market Interactions
The above description is typical of the expected market effects for a single product
markets (e.g., Small SI handheld and Class I nonhandheld; personal watercraft) considered in
isolation. However, several of the markets considered in this EIA are more complicated because
the engine and equipment manufacturers are not integrated.
When both engine and equipment markets are considered separately, the regulatory
program will affect equipment producers in two ways. First, equipment producers are affected
by higher input costs (increases in the price of gasoline engines) associated with the rule.
Second, the standards will also impose additional production costs on equipment producers
associated with equipment changes necessary to accommodate changes in engine design. In the
sections that follow, we describe the demand relationships between these markets and how they
are incorporated in the economic model.
In markets such as Class II nonhandheld or SD/I marine, the demand for engines is
directly linked to the production of equipment or vessels that uses those engines.9 This means
that it is reasonable to assume that the input-output relationship between the gasoline engines
and the equipment is strictly fixed and that the demand for engines varies directly with the
demand for equipment.10 A demand curve specified in terms of its downstream consumption is
referred to as a derived demand curve. Figure 9.2-5 illustrates how a derived demand curve is
identified.
9 In marine applications, one or two engines are used per boat, depending on its intrinsic design, and this
configuration is insensitive to small changes in engine used. In the case of Small SI equipment, the one-to-one
correspondence is exact. Furthermore, there is no potential for technical substitution, i.e., to make gasoline
equipment one needs a gasoline engine.
10 This one-to-one relationship holds for engines sold on the market and for engines consumed internally by
integrated engine/equipment manufacturers.
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Draft Regulatory Impact Analysis
Figure 9.2-5: Derived Demand for Engines
Price
Equipment
($/Q)
APr
AQr
Q - Equipment
Price
Engines
($/Q)
t
AP
eng
AQ
eng
Unit Cost Increase
Derived
Demand
Q - Engines
eng
Consider an event in the marine equipment market that causes the price of equipment to
increase by AP (such as an increase in the price of engines). This increase in the price of
equipment will cause the supply curve in the equipment market to shift up, leading to a
decreased quantity (AQE). The change in equipment production leads to a decrease in the
demand for engines (AQEng). The new point (QE - AQE, P - AP) traces out the derived demand
curve. Note that the supply and demand curves in the marine equipment markets are needed to
identify the derived demand in the engine market. All of the market supply and demand curves
and the elasticity parameters used in the EIM are described in Appendix 9E
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Economic Impact Analysis
9.2.3.3 Estimation of Social Costs
The economic welfare implications of the market price and output changes with the
regulation can be examined by calculating consumer and producer net "surplus" changes
associated with these adjustments. This is a measure of the negative impact of an environmental
policy change and is commonly referred to as the "social cost" of a regulation. It is important to
emphasize that this measure does not include the benefits that occur outside of the market, that
is, the value of the reduced levels of air pollution with the regulation. Including this benefit will
reduce the net cost of the regulation and even make it positive.
The demand and supply curves that are used to project market price and quantity impacts
can be used to estimate the change in consumer, producer, and total surplus or social cost of the
regulation (see Figure 9.2-6).
The difference between the maximum price consumers are willing to pay for a good and
the price they actually pay is referred to as "consumer surplus." Consumer surplus is measured
as the area under the demand curve and above the price of the product. Similarly, the difference
between the minimum price producers are willing to accept for a good and the price they actually
receive is referred to as "producer surplus." Producer surplus is measured as the area above the
supply curve below the price of the product. These areas can be thought of as consumers' net
benefits of consumption and producers' net benefits of production, respectively.
In Figure 9.2-6, baseline equilibrium occurs at the intersection of the demand curve, D,
and supply curve, S. Price is P[ with quantity Qj. The increased cost of production with the
regulation will cause the market supply curve to shift upward to S'. The new equilibrium price
of the product is P2. With a higher price for the product there is less consumer welfare, all else
being unchanged. In Figure 9.2-6(a), area A represents the dollar value of the annual net loss in
consumers' welfare associated with the increased price. The rectangular portion represents the
loss in consumer surplus on the quantity still consumed due to the price increase, Q2, while the
triangular area represents the foregone surplus resulting from the reduced quantity consumed,
Qi-Q2-
In addition to the changes in consumers' welfare, there are also changes in producers'
welfare with the regulatory action. With the increase in market price, producers receive higher
revenues on the quantity still purchased, Q2. In Figure 9.2-6(b), area B represents the increase in
revenues due to this increase in price. The difference in the area under the supply curve up to the
original market price, area C, measures the loss in producer surplus, which includes the loss
associated with the quantity no longer produced. The net change in producers' welfare is
represented by area B - C.
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Figure 9.2-6: Market Surplus Changes with Regulations
Consumer and Producer Surplus
$/Q
Q2 Q1
(a) Change in Consumer Surplus with
Regulation
Q/t
$/Q
Q2 Q1
(b) Change in Producer Surplus with
Regulation
Q/t
$/Q
Q2 Q1 Q/t
(c) Net Change in Economic Welfare with
Regulation
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Economic Impact Analysis
The change in economic welfare attributable to the compliance costs of the regulations is
the sum of consumer and producer surplus changes, that is, -(A) + (B-C). Figure 9.2-6(c) shows
the net (negative) change in economic welfare associated with the regulation as area D.
9.2.4 How Are Special Market Characteristics Addressed?
In addition to the general model features described in Section 9.2.2, there are several
specific characteristics of the Small SI and Marine SI markets that need to be addressed in the
EEVI. These are the treatment of fixed and variable costs, fuel savings, programmatic
flexibilities, and substitution, and distribution systems effects.
9.2.4.1 Fixed and Variable Costs in a Competitive Market
The estimated engineering compliance costs, consisting of fixed costs (R&D,
capital/tooling, certification costs), variable costs, and operating costs provide an initial measure
of total annual compliance costs without accounting for behavioral responses. The starting point
for assessing the market impacts of a regulatory action is to incorporate the regulatory
compliance costs into the production decision of the firm.
In general, shifting the supply curve by the total cost per unit implies that both capital
and operating costs vary with output levels. At least in the case of capital, this raises some
questions. In the long run, all inputs (and their costs) can be expected to vary with output. But a
short(er)-run analysis typically holds some capital factors fixed. For instance, to the extent that a
market supply function is tied to existing facilities, there is an element of fixed capital (or
one-time R&D). As indicated above, the current market supply function might reflect these
fixed factors with an upward slope. As shown in Figure 9.2-7, the marginal cost (MC) curve will
only be affected, or shift upwards, by the per-unit variable compliance costs (cl=TVCC/q),
while the average total cost (ATAC) curve will shift up by the per-unit total compliance costs
(c2=TCC/q). Thus, the variable costs will directly affect the production decision (optimal output
rate), and the fixed costs will affect the closure decision by establishing a new higher reservation
price for the firm (i.e., Pm'). In other words, the fixed costs are important in determining
whether the firm will stay in this line of business (i.e., produce anything at all), and the variable
costs determine the level (quantity) of production.
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Figure 9.2-7: Modeling Fixed Costs
$/q
q
(a) Upward-sloping supply function
Depending on the industry type, fixed costs associated with complying with a new
regulation can generally be treated differently in an analysis of market impacts. In a competitive
market, the industry supply curve is generally based on the market's marginal cost curve; fixed
costs do not influence production decisions at the margin. Therefore, the market anlaysis for a
competitive market is based on variable costs only.
The nature of the Small SI and Marine SI markets suggests the market supply curve shifts
in the model should include fixed and variable compliance costs. This is because Small SI and
Marine SI engine and equipment manufacturers produce a product that changes very little over
time. These manufacturers may not engage in research and development to improve their
products on a continuous basis (as opposed to highway vehicles or nonroad engines and
equipment). In this case, the product changes that would be required to comply with the
proposed standards would require these manufacturers to devote new funds and resources to
product redesign and facilities changes. In this situation, Small SI and Marine SI engine and
equipment manufacturers would be expected to increase their prices by the full amount of the
compliance costs (both fixed and variable) to attempt to recover those costs. This is in contrast
to the nonroad diesel engine and equipment markets: manufacturers in those markets generally
allocate redesign resources each year to accommodate a changing market. To reflect these
conditions, the supply shift in this EIM is based on both fixed and variable costs, even though
the model assumes perfect competition. A sensitivity analysis was performed to investigate the
impacts under the alternative scenario of shifting the supply curve by the variable costs only.
The results of that analysis can be found in Appendix 9H.
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9.2.4.2 Fuel Savings and Fuel Taxes
If all the costs of the regulation are not reflected in the supply shift, then the producer and
consumer surplus changes reflected in Figure 9.2-6(c) will not capture the total social costs of
the regulation. This will be the case, for example, if there are cost savings attributable to a
program that are not readily apparent to consumers.
In this case, the proposed evaporative and exhaust controls are expected to result in fuel
savings for users. Small SI engine and equipment manufacturers are expected to use fuel
injection techniques to comply with the proposed standards for some of their two-cylinder Class
II engines. These fuel injected engines are expected to have better fuel efficiency than
carbureted engines. Marine SI manufacturers are expected to use 4-stroke and direction-
injection 2-stroke technology for outboards and PWC. In addition, all sterndrive and inboard
engines are expected to use fuel injection. These technologies are expected to result in
reductions in fuel consumption.
These fuel savings are not included in the market analysis for this economic impact
analysis. This is because all available evidence suggests that fuel savings do not affect consumer
decisions with respect to the purchase of this equipment. Unlike motor vehicles or other
consumer goods, neither Small SI nor Marine SI equipment is labeled with expected fuel
consumption or expected annual operating costs. Therefore, there is no information available for
the consumer to use to make this decision. Instead consumers base their purchase decision on
other attributes of the product for which the manufacturer provides information. For lawn
mowers this may be the horsepower of the engine, whether the machine has a bag or has a
mulching feature, its blade size, etc. For PWC it may be how many people it can carry, its
maximum speed, its horsepower, etc. In many cases, especially for Small SI equipment, the
consumer may not even be aware of the fuel savings when operating the equipment, especially if
he or she uses the same portable fuel storage container to fuel several different pieces of
equipment.
These fuel savings are included in the social cost analysis. This is because they are
savings that accrue to society. These savings are attributed to consumers of the relevant
equipment. As explained in more detail in 9.3.5, the social cost analysis is based on the
equivalent of the pre-tax price of gasoline in that analysis. Although the consumer will realize a
savings equal to the pump price of gasoline (post-tax), part of that savings is offset by a tax loss
to governmental agencies and is thus a loss to consumers of the services supported by those
taxes. This tax revenue loss, considered a transfer payment in this analysis, does not affect the
benefit-cost analysis results.
9.2.4.3 Flexibility Provisions
Consistent with the engineering cost estimates, the EIM does not include cost savings
associated with compliance flexibility provisions or averaging, banking, and trading provisions.
As a result, the results of this EIA can be viewed as somewhat conservative.
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Draft Regulatory Impact Analysis
9.2.4.4 Substitution
Gasoline-powered SI engines convert the potential energy contained in the fuel into
mechanical energy, which can then be used to do useful work, to provide locomotion, and/or to
generate electricity. These machines are technologically similar compression-ignition engines
powered by diesel fuel, and often compete in the same equipment and applications markets.
Similarly, electric motors are capable of performing many of the same tasks as gasoline engines
in small and inexpensive equipment.
The relationships modeled in the EIM do not include substitution away from Small SI
and Marine SI engines and equipment to diesel or electric alternatives. This is appropriate
because consumers are not likely to make these substitutions. Diesel engines' superior
efficiency in energy conversion makes them more attractive for large engines, and for those with
long required service lives, whether measured in operating hours or years of service.
Gasoline-powered engines, on the other hand, have lower initial cost, and utilization in garden or
recreational activities is not high enough for diesel fuel efficiency to overcome this gasoline
advantage. On the SI marine side, the current population of recreational boats is
overwhelmingly powered by gasoline engines, even in the large horsepower classes where
diesel's superior efficiency would seem to provide significant cost advantages, and gasoline
engines are the prevalent choice for garden equipment and residential generators. On the Small
SI side, substitution to diesel is not a viable option for most residential consumers, either because
diesel equipment does not exist (e.g., diesel string trimmers) or because there would be a large
price premium that would discourage the use of diesel equipment (e.g., diesel lawnmowers and
diesel recreational marine vessels). In addition, most households are not equipped to handle the
additional fuel type and misfueling would carry a high cost. Finally, the lack of a large
infrastructure system already in place like the one supporting the use of gasoline equipment for
residential and recreational purposes, including refueling and maintenance, represents a large
barrier to substitution from gasoline to diesel equipment. With regard to electric alternatives, the
impact of substitution to electric for Small SI equipment (there are no comparable options for
Marine SI) is also expected to be negligible. Gasoline is the power source of choice for small
and inexpensive equipment due to its low initial cost. Gasoline equipment is also inherently
portable, which make them more attractive to competing electric equipment that must be
connected with a power grid or use batteries that require frequent recharging. Data that would
allow investigation of the details of this clear consumer preference are not available, but it is
reasonable to assume that increases in the cost of gasoline engines of the magnitude associated
with this program would not cause widespread substitution to diesel or electric alternatives.
9.2.4.5 Distribution System Effects
The market interactions modeled in the EIM are those between producers and consumers
of the specified engines and equipment that use those engines. The EIM does not consider sales
distribution networks or how the regulated goods are sold to final consumers through
wholesalers and/or retailers. This is appropriate because the proposed regulatory program does
not impose additional costs on the distribution networks and those relationships are not expected
to change as a result of the standards.
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In the case of Small SI equipment, however, concerns have been raised about the
potential for dominant retailers (big box stores such as Wal-Mart, Sears and K-Mart) to affect
market equilibria and the ability of manufacturers to pass along cost increases associated with
new emission control requirements. Specifically, some Small SI equipment manufacturers assert
that Big Box stores impose a price structure that would force them to absorb the compliance
costs associated with the proposed standards. They contend that this is a relatively new
phenomenon for their market and that EPA should consider these effects in the economic impact
analysis for this proposal.
Dominant retailers are a fairly well-understood sector of the consumer good distribution
network, especially with regard to clothing and household goods. These stores reduce product
prices by exerting important influences on relevant producers. Specifically, they discipline
markets by encouraging manufacturers to compete on price, and force inefficient firms to cut
costs or leave the market.
Dominant retailers may also prevent efficient producers from passing on increases in
fixed costs to consumers, including R&D costs associated with engine or equipment redesign.
So, for example, it may be the case that if a particular firm redesigns a lawnmower to produce
more power a dominant retailer may not choose to change its pricing structure to account for that
redesign. Nevertheless, the firm may still choose to incorporate the design change in the hope of
capturing a greater share of the market and/or improve its name recognition.
It is unlikely, however, that a dominant retailer could prevent firms from passing on
market-wide increases in marginal costs in response to a regulatory program. Profit maximizing
manufacturers will continue to follow a marginal cost equals price pricing rule regardless of the
distribution arrangements. A dominant retailer could not force the manufacturer to produce units
where the marginal cost exceeds the price. If large retail distributors attempted to prevent
efficient manufacturers from raising prices in response to the standards, manufacturers would
likely respond to a retailer's price pressure by reducing output. This would result in large excess
demand in the equipment market which would ultimately have to be satisfied through some sort
of arbitrage mechanism to a new higher equilibrium price.
An individual manufacturing company has little, if any, ability to pass on a price increase
if it is the only entity affected by that price increase. In such a case, retailers would clearly have
an incentive to purchase comparable engines or equipment that were not affected by the price
increase, placing the affected firm at a competitive disadvantage and reducing its market share.
However, in this case all engine manufacturers will face increased marginal costs of production
associated with the regulatory program. Therefore, the program does not necessarily put one
engine manufacturer at a competitive disadvantage, although manufacturers that can more easily
accommodate the new requirements will likely see lower costs than those who cannot.
9.3 EIM Data Inputs and Model Solution
The EIM is a computer model comprised of a series of spreadsheet modules that simulate
the supply and demand characteristics of the markets under consideration. The model equations,
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presented in Appendix D to this chapter, are based on the economic relationships described in
Section 9.2. The EIM analysis consists of four basic steps:
• Define the initial equilibrium conditions of the markets under consideration
(equilibrium prices and quantities and behavioral parameters; these yield
equilibrium supply and demand curves).
• Introduce a policy "shock" into the model based on estimated compliance costs
that shift the supply functions.
• Use a solution algorithm to estimate a new, with-regulation equilibrium price and
quantity for all markets.
Estimate the change in producer and consumer surplus in all markets included in
the model.
Supply responses and market adjustments can be conceptualized as an interactive
process. Producers facing increased production costs due to compliance are willing to supply
smaller quantities at the baseline price. This reduction in market supply leads to an increase in
the market price that all producers and consumers face, which leads to further responses by
producers and consumers and thus new market prices, and so on. The new with-regulation
equilibrium reflects the new market prices where total market supply equals market demand.
The remainder of this section describes the data used to construct the EIM: initial
equilibrium market conditions (equilibrium prices and quantities), compliance cost inputs, and
model elasticity parameters. Also included is a brief discussion of the analytical expression used
to estimate with-regulation market conditions.
9.3.1 Description of Product Markets
This EIM estimates the behavioral responses of the Small SI and Marine SI markets to
the cost of complying with the proposed emission control program. Each of these markets is
very briefly described below. More information can be found in the industry characterizations
prepared for this proposal (Chapter 1 and RTI 2006).
9.3.1.1 Small SI Market
The Small SI market is the market for a variety of nonroad equipment powered by two-
stroke or four-stroke spark-ignition engines rated up to 19 kW (25 hp). This economic impact
assessment distinguishes between two Small SI market sectors: handheld and nonhandheld. The
handheld (HH) sector consists generally of equipment that is carried by the operator and is
operated multipositionally, although some equipment in this category may have two wheels. HH
equipment includes string trimmers, edgers, leaf blowers, and chain saws. The nonhandheld
(NHH) sector consists mostly of wheeled equipment such as lawn mowers, garden tractors, and
wheeled trimmers, blowers, and edgers. Also included in the Small SI market are generators,
compressors, and construction, agricultural, and small industrial equipment, as well as some
recreational and utility vehicles and snowblowers.
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Economic Impact Analysis
The HH market can be characterized as an integrated market in which producers
manufacture both the engine and the associated equipment. In the NHH market, in contrast, the
engine and equipment manufacturers are typically separate entities. Engines produced by a
manufacturer for use in its own equipment are called "captive" engines. Engines produced by
manufacturers for sale on the open market to anyone who wants to buy them are called
"merchant" engines. This distinction is important because compliance costs affect captive and
merchant engines differently. Engine-related compliance costs for captive engines are absorbed
into the equipment costs of integrated suppliers in their entirety. In contrast, nonintegrated
suppliers who buy merchant engines absorb only part of the engine compliance costs into their
equipment costs; the rest is borne by the engine manufacturer. Depending on the price
sensitivity of demand in the engine market, the pass-through of engine compliance costs to the
equipment manufacturer may be larger (more inelastic demand) or smaller (more elastic
demand).
This analysis makes the simplifying assumption that virtually all Small SI equipment is
sold to residential end-users for their personal use and a negligible number are sold to
commercial entities for use as an input to the production of goods or services. This simplifying
assumption allows us to disregard the impact of the compliance costs on the production of goods
and services that would have Small SI equipment as an input. Any such impacts would be
expected to be negligible given the relative share of Small SI equipment to any such production
processes. This assumption is supported by data from the Outdoor Power Equipment and Engine
Service Association (OPEESA), contained in Table 9.3-1, which indicates that only about 3
percent of the NHH products sold in 2003 and 2004 were sold to commercial users. The rest, 97
percent, were sold to residential users. While this data reflects only NHH equipment, a similar
situation likely exists for HH equipment given the nature of that equipment (light-duty lawn and
garden equipment or gensets). Recent EPA certification data also supports this simplifying
assumption. According to model year 2005 data, about 5 percent of Class I and 7 percent of
Class II engines were high hour useful life (commercial) categories, or a total of about 9 percent
of Classes I and II combined. About 19 percent of HH engines were high useful life categories.
Table 9.3-1: Share of Residential and Commercial Small SI Shipments (Various years)
Total Commercial Turf Products
Total Consumer NHH Products
Commercial Unit Volume NHH Share
HH products (assumed consumer)
Commercial share - all Small SI
2003
297,085
8,598,901
3.3%
12,600,440
1.4%
2004
234,475
8.188,614
2.8%
11,949,557
1.2%
Source: Outdoor Power Equipment & Engine Service Association, 2004.
The analysis also assumes that there is a one-to-one correspondence between engines and
equipment (there is only one engine per equipment unit) and that there is no market for loose
engines. These assumptions are reasonable given the nature of this equipment and because
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Draft Regulatory Impact Analysis
owners generally do not repower this equipment when the engine fails; instead, they repair the
engine or replace the equipment. This assumption makes it possible to estimate the number of
engines produced directly from the number of equipment.
9.3.1.1.1 Handheld Market
The HH engine market consists of Class III (< 20 cc), IV (20-50 cc) and V (>50 cc)
engines. These engines are used in similar types of equipment, all of which are small and
relatively lightweight. According to the industry profile prepared for this rule, the HH market is
an integrated market in that about 90 percent of HH engines are "captive" engines, with the
engine and equipment manufacturer being the same company (RTI, 2006). An integrated market
means the EIM can use a one-market approach.
For the purpose of this analysis, all HH engines and equipment are grouped into one
engine/equipment market. This is reasonable both because it is an integrated market and because
the estimated compliance costs for the HH standards are expected to be similar for all types of
HH engines and equipment regardless of size or application. The proposed standards for HH
consist only of evaporative emission controls and tThe cost to comply with the standards are
primarily related to fuel tank volume and fuel hose length, which do not vary significantly for
most equipment.
9.3.1.1.2 NonhandheldMarket
The NHH engine market consists of Class I (<225 cc) and Class II (>225 cc) engines.
There are three useful life categories for each and the costs for complying with the exhaust
standards will vary by useful life category for each engine class. According to the industry
profile prepared for this rule, the NHH market is not integrated in that about 95 percent of Class
I and Class II NHH engines are merchant engines (RTI, 2006). The model thus explores the
impacts on engine producers and equipment producers separately. This means it is necessary to
use a two-market approach, with the engine and equipment markets sharing some of the
compliance costs and consumers bearing the rest.
Snowblowers engines are treated differently under EPA's proposed program. The
proposed program would impose only evaporative controls on these engines. Because Class I
manufacturers of snowblower engines make the whole engine as a set (i.e., including fuel tank
and fuel lines), it was decided to place all of the compliance costs on the engine manufacturer.
These manufacturers are expected to produce a separate snowblower engine to be used in this
equipment. Class II engines are commonly sold without fuel tanks, and so the evaporative
controls for Class II snowblowers are attributed to the equipment manufacturer.
The nine Small SI nonhandheld engine markets are summarized in Table 9.3-2.
Table 9.3-2: Small SI Nonhandheld Engine Categories
9-38
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Economic Impact Analysis
Class
Class I
Class I - Snowblower
Class II
Useful Life
125 hours
250 hours
500 hours
125 hours
250 hours
500 hours
250 hours
500 hours
1000 hours
The EIM includes eight types of NHH equipment, as described in Table 9.3-3. However,
because not all engine/equipment combination are applicable, there are a total of 40
engine/equipment markets. Specifically, there are no Class II lawnmowers, there are no Class I
tractors, and all equipment in the "other lawn and garden" category using Class I engines are in
the UL125 grouping.
Table 9.3-3: Nonhandheld Equipment Categories
Equipment
Agriculture/construction/general industrial
Utility and recreational vehicles
Lawn mowers
Tractors
Lawn and garden, other
Gensets/welders
Pumps/compressors/pressure washers
Snowblowers
Class I
Yes
Yes
Yes
No
UL125 only
Yes
Yes
Yes
Class II
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
9.3.1.2 Marine SI market
The Marine SI market is the market for a variety of marine vessels powered by gasoline
engines. These proposed Marine SI standards discussed here are for propulsion engines only.
Auxiliary Marine SI engines <37 kW are included as Small SI engines for this rule. Larger
auxiliary Marine SI engines were covered in the new standards for Large SI engines. Many of
the auxiliary Marine SI engines are being designed with catalysts independent of the proposed
9-39
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Draft Regulatory Impact Analysis
standards, so the proposed standards will codify what is already happening in the industry and
force new entrants in the market to employ the same types of emission controls. Given that the
industry is already using catalysts, the estimated costs of complying are with the proposed
standards are negligible. These engines typically use the same fuel tank as the propulsion
engines so evaporative emission controls for these engines impose a nominal cost that is already
covered in the vessel costs since the vessel costs include costs for hoses and tanks. The impact
of treating marine Auxiliary Marine SI engines in this way are expected to be minimal because
the number of vessels with installed auxiliary units is small and limited to sterndrive/inboard and
outboard luxury vessels: about 23,000 out of a total of 378,500 vessels.
9.3.1.2.1 Marine SI Engine Markets
Unlike Small SI engines that can be used in a variety of different types of equipment,
Marine SI engines are designed and manufactured for specific applications. Engines used in
sterndrive or inboard vessels are different from those used in outboard applications, and are
made by different manufacturers. Outboards and SD/I engines produced for luxury vessels are
different from those produced for the general market. Personal watercraft, on the other hand, are
generally an integrated system. Taking this into consideration, there are 15 engine markets
included in this EIA, based on design and horsepower. These are described in Table 9.3-4.
Table 9.3-4: Marine SI Engine Markets
Engine Design
PWC
SD/I Recreation
SD/I Luxury
OB Recreational
OB Luxury
<25hp
XXX
25-50 hp
XXX
5 1-100 hp
XXX
XXX
101-175 hp
XXX
XXX
XXX
XXX
176-300 hp
XXX
XXX
XXX
XXX
XXX
>301 hp
XXX
XXX
Similar to the Small SI market, most marine SI engines are used for recreational
purposes. According to a 2000 study of the boat building industry, about 79 percent of Marine
SI vessels are used for recreational purposes and only 7 percent for commercial purposes, with
the remaining 14 percent for other purposes (CCA, 2000).n The propulsion system of choice for
commercial marine vessels is diesel due to its greater reliability and lower fuel costs. The
combustion characteristics of diesel engines also make them a better choice for vessels that are
likely to spend large amounts of time at sea. While gasoline marine engines are used in
applications such as lifeboats, patrol boats and small fishing vessels, their numbers are not large
enough to warrant separate consideration in this Economic Impact Analysis.
"This study looked at NAICS 336612-establishments primarily engaged in building boats, defined as
watercraft not built in shipyards and typically of the type suitable or intended for personal use; it is not clear what is
meant by "other" in this study.
9-40
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Economic Impact Analysis
For the purposes of this analysis, all personal watercraft manufacturers are considered to
be integrated manufacturers, and thus the engines are "captive." This is reasonable because
personal watercraft are similar to land-based recreational vehicles in that the engines are
produced by the equipment manufacturer specifically for certain models.
The other two primary types of SI marine engines are outboards and sterndrives/inboards
(SD/I). For these engines, we model a merchant relationship between the engine manufacturers
and boat builders. This is reasonable because these engines are typically sold on the open
market (outboards) or sold internally but through a market-type relationship between the engine
and the equipment businesses (SD/I).
Outboard engines are typically produced by the engine manufacturer with little or no
knowledge of what vessels the engines will be used on. Outboards are a self-contained
assembly, with a power unit and drive unit, that can be fit to a wide range of boats. They may be
used either with a portable fuel tank or connected to a fuel system installed on a vessel. In most
cases, the engine manufacturer and boat builder are separate companies. However, it is
becoming more common for engine manufacturing companies to purchase boat builders. Based
on conversations with engine manufacturers and boat builders, we have received indications that
this trend has not significantly changed the relationship between the engine business units and
the boat building business units. The boat builders typically pay market price for the engines
and there is little integration of design beyond a typical manufacturer/supplier relationship. It
seems that engine manufacturers generally buy outboard vessel building companies to gain
access to target markets rather than to develop an integrated design. Generally, the vessel is sold
without the engine and the consumer chooses the engine at the point of sale. This means that the
vessel builder may not be involved in the transaction and that the distribution of the compliance
costs is between the engine builder and the end consumer rather than between the engine builder
and the vessel builder.
The relationship between engine manufacturers and boat builders is similar for SD/I
engines as for outboard engines. One difference is that there are only two large businesses and
many small businesses producing SD/I engines. These small businesses typically do not produce
boats or own companies that do. SD/I engines are often sold to buyer groups created by boat
builders to gain volume discounts on engines. Because of this, SD/I engine manufacturers often
do not know what boats their engines are being used in. In the case where a large SD/I
manufacturer has purchased boat building companies, the relationship is similar to that for
outboards. Nevertheless, the distribution of compliance costs would be between the engine
manufacturer and the vessel builder, since the engine is integrated in the final vessel design.
9.3.1.2.2 Marine SI Equipment Markets
There are five types of marine vessel markets:
• SD/I recreational (runabouts, airboats, jetboats)
• SD/I luxury (yachts, cruisers offshore)
OB recreational (runabouts, pontoons, fishing)
9-41
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Draft Regulatory Impact Analysis
• OB luxury (yacht, cruiser, express fish)
• Personal watercraft
Of the 30 possible engine/vessel combinations, there are 15 combinations that are not
applicable. For example, SD/I vessels use engines above 100 hp only. Personal watercraft use
engines above 50 hp but do not use engines above 300 hp. This yields a total of 15 engine/vessel
markets.
Table 9.3-5: Marine SI Vessel Types
Vessel
PWC
SD/I Recreational
SD/I Luxury
OB Recreational
OB Luxury
<25hp
XXX
25-50 hp
XXX
5 1-100 hp
XXX
XXX
101-175 hp
XXX
XXX
XXX
XXX
176-300 hp
XXX
XXX
XXX
XXX
XXX
>301 hp
XXX
XXX
Unlike Small SI equipment, there is not a one-to-one relationship between engines and
equipment. Some vessels may have more than one propulsion engine. Table 9.3-6 shows the
average number of engines per vessel assumed for the purposes of this analysis. In this table,
OB engines per boat sale represents the average number of engines per outboard vessel in
general. This average consists of three components: 1) some outboard vessels have more than
one engine; 2) engines that are made as replacement engines; and 3) loose engines that are not
sold with the boat, such as "kicker" engines which are used for low speed trolling.
Table 9.3-6: Average Number of Marine SI Engines per Vessel (2005)
Vessel
PWC
SD/I Recreational
SD/I Luxury
OB Recreational
OB Luxury
OB Engine/boat sale
<25hp
1.25
25-50 hp
1.25
51-100 hp
1.00
1.29
101-175 hp
1.00
1.00
1.29
2.50
176-300 hp
1.00
1.02
1.25
1.29
2.50
>301 hp
1.01
1.52
Average
1.00
1.01
1.39
1.28
2.50
1.47
9.3.1.3 Market Linkages
In the ELM, the Small SI and Marine SI markets are not linked (there is no feedback
mechanism between the Small SI and Marine SI market segments). This is appropriate because
the affected equipment is not interchangeable and because there is very little overlap between the
engine producers in each market. These two sectors represent different aspects of economic
9-42
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Economic Impact Analysis
activity (lawn and garden care and power generation as opposed to recreational marine) and
production and consumption of one product is not affected by the other. In other words, an
increase in the price of lawnmowers is not expected to have an impact on the production and
supply of personal watercraft, and vice versa. Production and consumption of each of these
productions are the results of other factors that have little cross-over impacts (the need for
residential garden upkeep or power generation; the desire for personal recreation).
9.3.2 Market Equilibrium Conditions
The starting point for the economic impact analysis is initial market equilibrium
conditions (prices and quantities) that exist prior to the implementation of new standards. At
pre-control market equilibrium conditions, consumers are willing to purchase the same amount
of a product that producers are willing to produce at the market price.
9.3.2.1 Small SI Initial Equilibrium Quantities and Prices
9.3.2.1.1 Small SI Engine and Equipment Initial Equilibrium Quantities
The EIM uses the same engine sales quantities that are used in the Small SI cost analysis
presented in Chapter 6. The sales numbers for 2005 are reproduced in Tables 9.3-7 and 9.3-8.
They are based on engine and equipment sales are for 49 states (all states except California) for
2005. However, the sales numbers include construction and agriculture equipment sold in
California, since that equipment is not covered by California's small engine program.
These engine sales numbers are taken from EPA's NONROAD 2005 emission inventory
model. To breakout the sales data by equipment, industry information from Power Systems
Research database-OELink was used to characterize the distribution of equipment by the eight
different equipment categories noted earlier. In addition, the sales within each equipment
category were apportioned to the different useful life categories based on the fraction of engines
certified in each class determined from EPA certification data for model year 2005.
Because of the one-to-one correspondence between Small SI engines and equipment, the
number of equipment is equal to the number of engines sold in a given year.
Table 9.3-7: Small SI Handheld Engine
and Equipment Sales (2005)
Sales - All Handheld Engines, Equipment
8,153,106
9-43
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Draft Regulatory Impact Analysis
Table 9.3-8: Small SI Nonhandheld Engine and
Equipment Sales (2005)
Application
Agricultural/Construction/
General Industrial/ Material
Handling Equip
Utility and Rec Vehicles
^awn Mowers
Tractors
^awn and Garden Other
Gensets/ Welders
3umps/ Compressors/
3ressure Washers
Snowblowers
Total
Class I
UL125
71,682
81,703
5,895,682
NA
647,256
271,391
579,773
551,506
8,098,993
UL250
7,675
8,748
631,264
NA
NA
29,058
62,078
59,051
797,874
UL500
5,287
6,026
434,859
NA
NA
20,017
42,763
40,679
549,631
Class II
UL250
71,380
173,846
NA
1,701,351
127,915
605,169
253,971
475,353
3,408,985
UL500
15,503
37,758
NA
369,523
27,782
131,439
55,161
103,244
740,410
UL1000
17,585
42,827
NA
419,134
31,512
149,086
62,576
117,105
839,816
Total
189,112
350,908
6,961,805
2,490,008
834,465
1,206,160
1,056,322
1,346,938
14,435,709
9.3.2.1.2 Small SI Engine and Equipment Initial Equilibrium Prices
The initial equilibrium prices for Small SI engines and equipment are contained in Tables
9.3-9 and 9.3-10. The engine prices were prices estimated by EPA using prices compiled from
various websites and obtained from manufacturers. The engine prices were averaged for each
useful life category for each class. The equipment prices were gathered through a survey of
retailers, government dealers, and equipment websites (Caffrey, 2006).
For the handheld market, although all costs are placed on the engine manufacturer, the
engine and equipment manufacturers are integrated so only the equipment price is necessary for
the analysis.
Table 9.3-9: Small SI Handheld Engine and
Equipment Prices (2005$)
Equipment Price
$87
9-44
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Economic Impact Analysis
Table 9.3-10: Small SI Nonhandheld Engine and
Equipment Equilibrium (2005$)
Application
Agricultural/Construction/ General
industrial/ Material Handling Equip
Utility and Rec Vehicles
^awn Mowers
Tractors
^awn and Garden Other
Gensets/ Welders
3umps/ Compressors/ Pressure Washers
Snowblowers
Class I
UL 125
$1,108
$570
$218
$245
$999
$96
$324
UL250
$1,621
$750
$420
$1,428
$661
$480
UL500
$2,133
$931
$2,786
$1,856
$1,225
$637
Class II
UL250
$1,825
$2,894
$1,937
$312
$666
$349
$665
UL500
$3,538
$3,981
$5,241
$969
$1,414
$1,485
$890
UL 1000
$5,251
$5,068
$6,841
$1,626
$2,162
$2,834
$1,115
9.3.2.2 Marine SI Initial Equilibrium Quantities and Prices
9.3.2.2.1 Marine SI Engine and Equipment InitialEquilibrium Quantities
The EIM uses the same engine sales quantities that are used in the Marine SI cost
analysis presented in Chapter 6. The sales numbers for 2005 are reproduced in Tables 9.3-11
and 9.3-12. The engine sales data are derived for 2003 from certification databases for EPA and
the California Air Resources Board and nationwide statistical data published by the National
Marine Manufacturers Association (Samulski, 2004). These 2003 sales were adjusted to 2005
and future years using the growth rate described in 9.3.4.
Table 9.3-11: Marine SI Engine Sales (2005)
Vessel
PWC
SD/I Recreational
SD/I Luxury
OB Recreational
OB Luxury
OB loose engines
Total
<25hp
38,529
32,667
71,196
25-50 hp
52,858
52,858
51-100 hp
20,825
79,083
99,909
101-175 hp
57,257
15,069
46,229
9,043
127,599
176-300 hp
3,767
35,668
9,565
42,680
9,043
100,724
>301 hp
25,975
12,960
38,935
Total
81,849
76,712
22,525
259,380
18,087
32,667
491,220
9-45
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Draft Regulatory Impact Analysis
Table 9.3-12: Marine SI Vessel Sales (2005)
Vessel
PWC
SD/I Recreational
SD/I Luxury
OB Recreational
OB Luxury
Total
<25hp
30,823
30,823
25-50 hp
42,287
42,287
51-100 hp
20,825
61,182
82,007
101-175 hp
57,257
15,069
35,765
3,617
111,708
176-300 hp
3,767
34,894
7,630
33,019
3,617
82,928
>301 hp
25,645
8,542
34,186
Total
81,849
75,608
16,172
203,076
7,235
383,940
9.3.2.2.2 Marine SI Engine and Vessel InitialEquilibrium Prices
The Marine SI engine and vessel initial equilibrium prices are contained in Tables 9.3-13
and 9.3-14. They are based on advertised prices in trade literatures and on the web and on
statistical data collected by the National Marine Manufacturers Association (Samulski, 2004).
For the estimated vessel prices, replacement engines are included but are discounted at 7 percent
for outboard recreational and luxury outboard and sterndrive vessels. The discount is used to
account for the assumption that replacement engines are purchased several years after the boat is
purchased. For this analysis, the discount is based on the average useful engine life estimates in
the NONROAD2005 model. The original price data was 2003 data; these were adjusted by
applying the Product Price Index Series published by the U.S. Bureau of Labor Statistics.12
Table 9.3-13: Marine SI Engine Prices (2005$)
Vessel
PWC
SD/I Recreational
SD/I Luxury
OB Recreational
OB Luxury
OB loose engines
<25hp
$2,606
$2,491
25-50 hp
$5,693
5 1-100 hp
N/A
$9,114
101-175 hp
N/A
$7,577
$13,481
$26,001
176-300 hp
N/A
$12,604
$16,508
$20,786
$40,074
>301 hp
$18,715
$31,959
12For Marine SI engines, the PPI for Gasoline Engines (except aircraft, automobile, highway truck, bus, and
tank; PCU3336183336181) was used; the ratio for this index is 110.1/105.7= 1.042. For marine vessel, the PPI for
Boat Building (PCU 336612336612) was used; the ratio for this index is 206.7/194.2 = 1.064.
9-46
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Economic Impact Analysis
Table 9.3-14: Marine SI Vessel Prices* (2005$)
Vessel
PWC
SD/I Recreational
SD/I Luxury
OB Recreational
OB Luxury
<25hp
$3,658
25-50 hp
$10,884
5 1-100 hp
$7,566
$21,561
101-175 hp
$9,982
$16,549
$32,467
$65,097
176-300
hp
$11,960
$32,356
$58,024
$49,420
$104,562
>301 hp
$46,432
$205,658
* Includes replacement engines discounted at 7% for outboard recreational and luxury outboard in sterndrive/inboard
vessels.
9.3.3 Compliance Costs
The social costs of the proposed standards are estimated by shocking the initial market
equilibrium conditions by the amount of the compliance costs. The compliance costs used in this
analysis are the engineering compliance costs described in Chapters 6 of this RIA and are
summarized in this section.
The fixed cost portion of the engineering costs incorporate a 7 percent cost of capital
recovered over the first five years of the exhaust standards even though the costs actually occur
prior to the beginning of the program. The period of recovery is 2011 through 2015 for Class I
Small SI engines and 2012 through 2016 for Class II Small SI engines. Marine engine fixed
costs are recovered over the period 2009 through 2013 for engines and 2011 through 2016 for
vessels, PWC, and outboards <25 hp. The other marine vessels have a small amount of fixed
costs associated with the evaporative controls.
9.3.3.1 Small SI Market Compliance Costs
The Small SI engine and equipment compliance costs are summarized in Tables 9.3-15
and 9.3-16. There is one set of compliance costs for HH engines, since there is only one market.
There are nine sets of engine compliance costs for NHH engines, one for each engine market.
These costs begin in 2009 for HH and 2008 for NHH; the costs changes over time reflecting the
phase-in of the different standards.
There are no equipment compliance cost estimates for HH or for Class I NHH equipment.
Since the HH market is integrated, all costs are applied to engines. For NHH Class I equipment,
the engine manufacturers typically produce a complete engine and fuel system package.
Therefore, the proposed program is not expected to impose any additional costs on the
equipment manufacturers. Costs are provided for NHH Class II equipment, reflecting the need
for evaporative and emission controls. An average cost for all Class II equipment was applied in
this analysis to each of the equipment categories.
9-47
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Draft Regulatory Impact Analysis
Table 9.3-15: Compliance Costs per Engine - Small SI (2005$)
Class
Useful
Life
Cost
Type
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017+
Handheld
All Engines
Variable
Fixed
Total
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.81
$0.01
$0.82
$0.81
$0.01
$0.82
$0.81
$0.01
$0.82
$0.81
$0.01
$0.82
$0.81
$0.01
$0.82
$0.69
$0.00
$0.69
$0.69
$0.00
$0.69
$0.69
$0.00
$0.69
Nonhandheld
1
1
1
1
1
1
2
2
2
125
250
500
125
Snow-
blower
250
Snow-
blower
500
Snow-
blower
250
500
1,000
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$0.33
$0.02
$0.35
$32.74
$3.63
$36.37
$25.87
$6.13
$32.00
$58.53
$16.00
$74.53
$13.30
$1.53
$14.83
$15.64
$4.91
$20.55
$19.46
$7.03
$26.49
$2.69
$0.47
$3.16
$2.69
$0.47
$3.16
$2.69
$0.47
$3.16
$32.74
$3.56
$36.30
$25.87
$6.02
$31.89
$58.53
$15.73
$73.99
$13.17
$1.49
$14.66
$15.51
$4.81
$20.32
$19.33
$6.89
$26.22
$2.56
$0.45
$3.01
$2.56
$0.45
$3.01
$2.56
$0.45
$3.01
$32.74
$3.50
$36.24
$25.87
$5.92
$31.79
$58.53
$15.46
$73.73
$13.19
$1.47
$14.66
$15.53
$4.74
$20.26
$19.35
$6.79
$26.13
$2.58
$0.45
$3.03
$2.58
$0.45
$3.03
$2.58
$0.45
$3.03
$32.74
$3.44
$36.18
$25.87
$5.82
$31.69
$58.53
$15.20
$73.73
$13.19
$1.46
$14.64
$15.53
$4.67
$20.19
$19.35
$6.68
$26.03
$2.58
$0.45
$3.03
$2.58
$0.45
$3.03
$2.58
$0.45
$3.03
$32.74
$3.39
$36.13
$25.87
$5.73
$31.60
$58.53
$14.96
$73.49
$13.19
$1.44
$14.63
$15.53
$4.60
$20.13
$19.35
$6.59
$25.93
$2.58
$0.45
$3.03
$2.58
$0.45
$3.03
$2.58
$0.45
$3.03
$27.06
$0.00
$27.06
$21.63
$0.00
$21.63
$45.00
$0.00
$45.00
$11.95
$0.19
$12.14
$14.21
$0.19
$14.40
$17.73
$0.19
$17.92
$2.10
$0.19
$2.29
$2.10
$0.19
$2.29
$2.10
$0.19
$2.29
$27.06
$0.00
$27.06
$21.63
$0.00
$21.63
$45.00
$0.00
$45.00
-------
Economic Impact Analysis
Table 9.3-16: Compliance Costs per Equipment - Small SI (2005$)
Class
Useful
Life
Cost
Type
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017+
Handheld
All Engines
Variable
Fixed
Total
No equipment costs for HH; all costs are allocated to engine manufacturer
Nonhandheld
1
2
2
2
125
250
500
1000
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
No equipment costs for NHH Class I; all costs are allocated to engine manufacturer
$1.09
$0.04
$1.13
$1.09
$0.04
$1.13
$1.09
$0.04
$1.13
$1.09
$0.04
$1.13
$1.09
$0.04
$1.13
$1.09
$0.04
$1.13
$1.09
$0.04
$1.13
$1.09
$0.04
$1.13
$1.09
$0.04
$1.13
$6.44
$5.11
$11.55
$6.44
$19.03
$25.47
$6.44
$16.93
$23.36
$6.44
$5.05
$11.48
$6.44
$18.73
$25.16
$6.44
$16.66
$23.10
$6.31
$4.94
$11.24
$6.31
$18.38
$24.69
$6.31
$16.35
$22.66
$6.31
$4.87
$11.18
$6.31
$18.10
$24.41
$6.31
$16.10
$22.41
$6.31
$4.81
$11.12
$6.31
$17.83
$24.13
$6.31
$15.86
$22.16
$5.40
$0.68
$6.08
$5.40
$0.68
$6.08
$5.40
$0.68
$6.08
$5.40
$0.68
$6.08
$5.40
$0.68
$6.08
$5.40
$0.68
$6.08
9.3.3.2 Marine SI Market Compliance Costs
The Marine SI engine and equipment compliance costs are summarized in Tables 9.3-17
and 9.3-18. Cost estimates are given for each of the 15 engine/equipment combinations, plus
cost estimates for loose OB engines. The engine costs begin in 2009 and decrease in 2014 when
the fixed costs are fully amortized. In addition, we apply a one time learning curve correction to
the variable cost in the sixth year. The engine compliance costs remain the same for 2014 and
later years. The equipment costs are more complicated due to the phase in of the different
standards. They begin in 2009, increase until about 2012, and then decrease in 2018. Equipment
compliance costs remain the same for 2018 and later years.
9-49
-------
Table 9.3-17: Compliance Costs per Engine - Marine SI (2005$)
Application
Category
PWC
PWC
PWC
SD/I Recreational
SD/I Recreational
SD/I Recreational
SD/I Luxury
SD/I Luxury
OB Recreational
HP
Category
50-100
100-175
175-300
100-175
175-300
300 +
175-300
300 +
<25
Cost
Type
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
2008
2009
$870
$29
$899
$85
$13
$98
$1,290
$45
$1,335
$421
$19
$440
$292
$20
$312
$349
$28
$377
$292
$20
$312
$349
$28
$377
$69
2010
$870
$29
$899
$85
$13
$98
$1,290
$45
$1,335
$421
$19
$440
$292
$20
$312
$349
$28
$377
$292
$20
$312
$349
$28
$377
$69
2011
$870
$29
$899
$85
$13
$98
$1,290
$45
$1,335
$421
$19
$440
$292
$20
$312
$349
$28
$377
$292
$20
$312
$349
$28
$377
$69
2012
$870
$29
$899
$85
$13
$98
$1,290
$45
$1,335
$421
$19
$440
$292
$20
$312
$349
$28
$377
$292
$20
$312
$349
$28
$377
$69
2013
$870
$29
$899
$85
$13
$98
$1,290
$45
$1,335
$421
$19
$440
$292
$20
$312
$349
$28
$377
$292
$20
$312
$349
$28
$377
$69
2014
$696
—
$696
$68
...
$68
$1,032
...
$1,032
$337
...
$337
$234
...
$234
$279
...
$279
$234
...
$234
$279
...
$279
$55
2015
$696
...
$696
$68
...
$68
$1,032
...
$1,032
$337
...
$337
$234
...
$234
$279
...
$279
$234
...
$234
$279
...
$279
$55
2016
$696
...
$696
$68
...
$68
$1,032
...
$1,032
$337
...
$337
$234
...
$234
$279
...
$279
$234
...
$234
$279
...
$279
$55
2017
$696
...
$696
$68
...
$68
$1,032
...
$1,032
$337
...
$337
$234
...
$234
$279
...
$279
$234
...
$234
$279
...
$279
$55
2018-23
$696
...
$696
$68
...
$68
$1,032
...
$1,032
$337
...
$337
$234
...
$234
$279
...
$279
$234
...
$234
$279
...
$279
$55
2024+
$696
...
$696
$68
...
$68
$1,032
...
$1,032
$337
...
$337
$234
...
$234
$279
...
$279
$234
...
$234
$279
...
$279
$55
-------
Application
Category
OB Recreational
OB Recreational
OB Recreational
OB Recreational
OB Luxury
OB Luxury
OB Loose Engines
HP
Category
25-50
50-100
100-175
175-300
100-175
175-300
<25
Cost
Type
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
2008
2009
$5
$74
$216
$6
$222
$203
$8
$211
$338
$15
$353
$690
$27
$717
$338
$15
$353
$690
$27
$717
$69
$5
$74
2010
$5
$74
$216
$6
$222
$203
$8
$211
$338
$15
$353
$690
$27
$717
$338
$15
$353
$690
$27
$717
$69
$5
$74
2011
$5
$74
$216
$6
$222
$203
$8
$211
$338
$15
$353
$690
$27
$717
$338
$15
$353
$690
$27
$717
$69
$5
$74
2012
$5
$74
$216
$6
$222
$203
$8
$211
$338
$15
$353
$690
$27
$717
$338
$15
$353
$690
$27
$717
$69
$5
$74
2013
$5
$74
$216
$6
$222
$203
$8
$211
$338
$15
$353
$690
$27
$717
$338
$15
$353
$690
$27
$717
$69
$5
$74
2014
—
$55
$173
...
$173
$162
...
$162
$270
...
$270
$552
...
$552
$270
...
$270
$552
$552
$55
$55
2015
...
$55
$173
...
$173
$162
...
$162
$270
...
$270
$552
...
$552
$270
...
$270
$552
$552
$55
$55
2016
...
$55
$173
...
$173
$162
...
$162
$270
...
$270
$552
...
$552
$270
...
$270
$552
$552
$55
$55
2017
...
$55
$173
...
$173
$162
...
$162
$270
...
$270
$552
...
$552
$270
...
$270
$552
$552
$55
$55
2018-23
...
$55
$173
...
$173
$162
...
$162
$270
...
$270
$552
...
$552
$270
...
$270
$552
$552
$55
$55
2024+
...
$55
$173
...
$173
$162
...
$162
$270
...
$270
$552
...
$552
$270
...
$270
$552
$552
$55
$55
-------
Table 9.3-18: Compliance Costs per Equipment- Marine SI (2005$)
Application
Category
PWC
PWC
PWC
SD/I
Recreational
SD/I
Recreational
SD/I
Recreational
SD/I
Luxury
SD/I
Luxury
HP Category
50-100
100-175
175-300
100-175
175-300
300 +
175-300
300 +
Cost Type
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
2008
2009
$1.6
$0.4
$1.9
$1.9
$0.4
$2.3
$1.9
$0.4
$2.3
$3.8
$0.5
$4.4
$4.5
$0.5
$5.0
$5.2
$0.5
$5.7
$9.0
$0.5
$9.6
$10.3
$0.5
$10.9
2010
$1.6
$0.4
$1.9
$1.9
$0.4
$2.3
$1.9
$0.4
$2.3
$31.4
$0.5
$31.9
$42.8
$0.5
$43.3
$70.7
$0.5
$71.2
$85.5
$0.5
$86.0
$141.4
$0.5
$141.9
2011
$3.8
$12.1
$15.9
$4.7
$13.3
$18.0
$4.7
$13.3
$18.0
$31.4
$0.5
$31.9
$42.8
$0.5
$43.3
$70.7
$0.5
$71.2
$85.5
$0.5
$86.0
$141.4
$0.5
$141.9
2012
$3.8
$12.1
$15.9
$4.7
$13.3
$18.0
$4.7
$13.3
$18.0
$67.2
$0.6
$67.8
$92.3
$0.6
$93.0
$155.6
$0.6
$156.3
$184.7
$0.8
$185.4
$311.2
$0.8
$312.0
2013
$3.8
$12.1
$15.9
$4.7
$13.3
$18.0
$4.7
$13.3
$18.0
$67.2
$0.6
$67.8
$92.3
$0.6
$93.0
$155.6
$0.6
$156.3
$184.7
$0.8
$185.4
$311.2
$0.8
$312.0
2014
$3.8
$12.1
$15.9
$4.7
$13.3
$18.0
$4.7
$13.3
$18.0
$67.2
$0.6
$67.8
$92.3
$0.6
$93.0
$155.6
$0.6
$156.3
$184.7
$0.8
$185.4
$311.2
$0.8
$312.0
2015
$3.8
$12.1
$15.9
$4.7
$13.3
$18.0
$4.7
$13.3
$18.0
$67.2
$0.6
$67.8
$92.3
$0.1
$92.4
$155.6
$0.1
$155.7
$184.7
$0.2
$184.9
$311.2
$0.2
$311.5
2016
$3.8
$12.1
$15.9
$4.7
$13.3
$18.0
$4.7
$13.3
$18.0
$61.7
$0.1
$61.8
$84.7
$0.1
$84.8
$142.5
$0.1
$142.6
$169.4
$0.2
$169.6
$285.0
$0.2
$285.3
2017
$3.8
$5.9
$9.7
$4.7
$6.5
$11.2
$4.7
$6.5
$11.2
$61.7
$61.7
$84.7
$84.7
$142.5
...
$142.5
$169.4
...
$169.4
$285.0
...
$285.0
2018-23
$3.8
$5.9
$9.7
$4.7
$6.5
$11.2
$4.7
$6.5
$11.2
$56.3
$56.3
$78.9
$78.9
$135.6
...
$135.6
$157.8
...
$157.8
$271.3
...
$271.3
2024+
$3.8
$5.9
$9.7
$4.7
$6.5
$11.2
$4.7
$6.5
$11.2
$56.3
$56.3
$78.9
$78.9
$135.6
...
$135.6
$157.8
...
$157.8
$271.3
...
$271.3
-------
Application
Category
OB
Recreational
OB
Recreational
OB
Recreational
OB
Recreational
OB
Recreational
OB
Luxury
OB
Luxury
OB
Loose
Engines
HP Category
<25
25-50
50-100
100-175
175-300
100-175
175-300
<25
Cost Type
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
Variable
Fixed
Total
2008
2009
$3.1
$0.2
$3.3
$4.4
$0.5
$5.0
$6.5
$0.5
$7.0
$7.7
$0.5
$8.3
$9.0
$0.5
$9.6
$15.5
$0.5
$16.0
$18.1
$0.5
$18.6
$3.0
$6.0
$3.0
2010
$4.4
$0.2
$4.6
$17.3
$0.5
$17.8
$26.7
$0.5
$27.3
$40.6
$0.5
$41.1
$57.9
$0.5
$58.4
$81.1
$0.5
$81.6
$115.8
$0.5
$116.4
$4.0
$0.0
$5.0
2011
$5.4
$6.7
$12.0
$17.3
$0.5
$17.8
$26.7
$0.5
$27.3
$40.6
$0.5
$41.1
$57.9
$0.5
$85.4
$81.1
$0.5
$81.6
$115.8
$0.5
$116.4
$5.0
$7.0
$12.0
2012
$5.4
$6.7
$12.0
$30.9
$0.6
$31.6
$47.7
$0.6
$48.3
$73.8
$0.6
$74.5
$107.0
$0.6
$107.6
$147.6
$0.8
$148.4
$213.9
$0.8
$214.7
$5.0
$7.0
$12.0
2013
$5.4
$6.7
$12.0
$30.9
$0.6
$31.6
$47.7
$0.6
$48.3
$73.8
$0.6
$74.5
$107.0
$0.6
$107.6
$147.6
$0.8
$148.4
$213.9
$0.8
$214.7
$5.0
$7.0
$12.0
2014
$5.4
$6.7
$12.0
$30.9
$0.6
$31.6
$47.7
$0.6
$48.3
$73.8
$0.6
$74.5
$107.0
$0.6
$107.6
$147.6
$0.8
$148.4
$213.9
$0.8
$214.7
$5.0
$7.0
$12.0
2015
$5.4
$6.7
$12.0
$30.9
$0.6
$31.6
$47.7
$0.6
$48.3
$73.8
$0.6
$74.5
$107.0
$0.6
$107.6
$147.6
$0.8
$148.4
$213.9
$0.8
$214.7
$5.0
$6.0
$12.0
2016
$5.1
$3.2
$8.3
$28.3
$0.1
$28.5
$43.6
$0.1
$43.7
$67.3
$0.1
$67.4
$97.2
$0.1
$97.3
$134.5
$0.2
$134.7
$14.4
$0.2
$194.6
$5.0
$6.0
$12.0
2017
$5.1
$3.2
$8.3
$28.3
$0.1
$28.5
$43.6
$0.1
$43.7
$67.3
$0.1
$67.4
$97.2
$0.1
$97.3
$134.5
$0.2
$134.7
$14.4
$0.2
$194.6
$5.0
$3.0
$8.0
2018-23
$5.1
$3.2
$8.3
$23.6
—
$23.6
$38.6
...
$38.6
$61.7
...
$61.7
$91.0
...
$91.0
$123.4
...
$123.4
$182.0
...
$182.0
$5.0
$3.0
$8.0
2024+
$6.1
$6.5
$12.6
$23.6
...
$23.6
$38.6
...
$38.6
$61.7
...
$61.7
$91.0
...
$91.0
$123.4
...
$123.4
$182.0
...
$182.0
$6.0
$6.0
$13.0
-------
Draft Regulatory Impact Analysis
9.3.4 Growth Rates
The growth rates used in this analysis for future Small SI and Marine SI engines and
equipment sales are from EPA's Nonroad 2005 model and are the same the same as those use for
the cost analysis (EPA 2004b). Because the growth rates are linear, the annual growth rate
decreases over time. For Small SI, the growth rate is approximately 2 percent per year beginning
in 2008 to decreases to approximately 1.5 percent for 2020 and later years. The growth rate for
Marine SI is about 0.8 percent per year in the early years and 0.6 percent in later years.
9.3.5 Fuel Savings
As noted in Section 9.2.4.2, there are fuel savings attributable to the proposed emission
control program, reflecting the reduction in evaporative emissions and the use of more
fuel-efficient engine technology to meet the proposed engine exhaust standards. As explained in
that section, these savings are included in the economic welfare analysis as a separate line item.
Consumers of Small SI and Marine SI engines and equipment will realize an increase in their
welfare equivalent to the amount of gallons of gasoline saved multiplied by the retail price of the
gasoline (post-tax price). In the engineering cost analysis the fuel savings are estimated in this
manner. However, in the context of the social welfare analysis, some of this increase in
consumer welfare is offset by lost tax revenues to local, state, and federal governments. These
welfare losses must be accounted for as well. Therefore, the net change in social welfare is the
difference between the increase in consumer welfare and the lost tax revenues. This is
equivalent to using the pre-tax price of gasoline to estimate the fuel savings for the social welfare
analysis.
The amount of gallons of gasoline fuel saved is composed of two parts. First, upgrades
in engine technology is expected to reduce fuel consumption rates. These fuel consumption
reductions were calculated using the NONROAD2005 model. In addition, fuel savings due to
evaporative emission control is estimated based on the VOC reductions attributable to these
controls. Tons of annual VOC reductions are translated to gallons of gasoline saved using a fuel
density of 6 Ibs per gallon (for lighter hydrocarbons which evaporate first).
Because the gallons of gasoline saved are based on estimated national reductions and
were not estimated by PADD, we estimated a national average retail gasoline price (RTI,
Memorandum on Calculation Motor Gasoline Prices in Small SI rule EIA, 2006). This estimate
is the sum of the weighted average of pre-tax gasoline prices by PADD and the weighted average
gasoline tax by PADD, using data from the 2005 Petroleum Marketing Annual (DoE 2005, Table
31). The results of this analysis are shown in Tables 13.3-19 and 13.3-20.
9-54
-------
Economic Impact Analysis
Table 9.3-19: Estimated National Average Fuel Prices (2005$)
PADD
PADD 1
PADD 2
PADD 3
PADD 4
PADD 5
(excluding CA)
Total
Weight
0.40
0.31
0.18
0.04
0.07
Pre-tax
Price/Gallon
$1.819
$1.792
$1.787
$1.848
$1.938
$1.814
Average State
Taxes
$0.207
$0.209
$0.194
$0.225
$0.198
Federal Tax
$0.184
$0.184
$0.184
$0.184
$0.184
Post-Tax
Price/Gallon
$2.210
$2.185
$2.165
$2.257
$2.320
$2.204
Source: 2005 Petroleum Marketing Annual (Table 31). U.S. Department of Energy, Energy Information
Administration (DoE 2005). Memorandum on Calculation Motor Gasoline Prices in Small SI Rule EM, RTI, 2006.
From 2009 until 2016 the estimated consumer savings associated with reduced gasoline
consumption from the gas can controls increases sharply, from $16.7 million to $244 million.
After 2016 the savings continue to accrue, but at a reduced rate as the engines and equipment
population turns over and fuel savings are due to the continuing benefits of using compliant
engines and equipment. Similarly, the tax revenue losses are expected to be increased from $3
million in 2009 to $43 million in 2016.
9-55
-------
Draft Regulatory Impact Analysis
Table 13.3-20: Estimated Fuel Savings and Tax Revenue Impacts (2005$)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
Small SI
Gallons
1,710,034
3,430,377
5,447,927
22,646,301
38,820,204
51,968,776
60,526,996
67,159,572
72,453,313
75,973,455
78,721,263
81,051,936
83,107,200
84,875,051
86,484,675
87,990,954
89,466,431
90,924,555
92,374,877
93,815,016
95,245,161
96,666,097
98,077,275
99,481,730
100,883,561
102,282,368
103,678,793
105,073,460
106,463,214
107,848,254
109,231,748
Marine SI
Gallons
0
4,143,348
8,561,114
13,117,609
18,222,489
23,304,500
28,367,111
33,371,341
38,326,645
43,218,105
48,034,529
52,441,003
56,436,144
60,288,468
63,989,930
67,173,629
70,031,410
72,627,522
74,999,472
77,157,506
79,117,289
80,838,412
82,349,823
83,737,102
84,965,626
86,094,905
87,140,798
88,101,996
88,990,652
89,818,189
90,613,170
Total Gallons
1,710,034
7,573,726
14,009,041
35,763,910
57,042,693
75,273,275
88,894,107
100,530,913
110,779,958
119,191,560
126,755,792
133,492,939
139,543,344
145,163,518
150,474,605
155,164,583
159,497,841
163,552,076
167,374,349
170,972,522
174,362,449
177,504,508
180,427,098
183,218,832
185,849,187
188,377,272
190,819,590
193,175,456
195,453,866
197,666,443
199,844,918
Consumer
Fuel Savings
(Million$)
$3.8
$16.7
$30.9
$78.8
$125.7
$165.9
$195.9
$221.5
$244.1
$262.6
$279.3
$294.2
$307.5
$319.9
$331.6
$341.9
$351.5
$360.4
$368.8
$376.7
$384.2
$391.1
$397.6
$403.7
$409.5
$415.1
$420.5
$425.7
$430.7
$435.6
$440.4
Tax Revenue
Impacts
(Million$)
$0.7
$3.0
$5.5
$13.9
$22.2
$29.3
$34.7
$39.2
$43.2
$46.5
$49.4
$52.0
$54.4
$56.6
$58.7
$60.5
$62.2
$63.8
$65.2
$66.6
$68.0
$69.2
$70.3
$71.4
$72.4
$73.4
$74.4
$75.3
$76.2
$77.1
$77.9
Net Fuel
Savings
(MillionsS)
$3.1
$13.7
$25.4
$64.9
$103.5
$136.5
$161.2
$182.3
$200.9
$216.2
$229.9
$242.1
$253.1
$263.3
$272.9
$281.4
$289.3
$296.6
$303.6
$310.1
$316.3
$321.9
$327.3
$332.3
$337.1
$341.7
$346.1
$350.4
$354.5
$358.5
$362.5
9.3.6 Supply and Demand Elasticity Estimates
The estimated market impacts and economic welfare costs of this emission control
program are a function of the ways in which producers and consumers of the Small SI and
Marine SI engines and equipment affected by the standards change their behavior in response to
the costs incurred in complying with the standards. These behavioral responses are incorporated
in the EEVI through the price elasticity of supply and demand (reflected in the slope of the supply
and demand curves), which measure the price sensitivity of consumers and producers.
Because we were unable to find published supply and demand elasticities for the Small
SI and Marine SI markets, we estimated these parameters using the procedures described in
Appendix 9E. These methods are well-documented and are consistent with generally accepted
9-56
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Economic Impact Analysis
econometric practice. It should be noted that these elasticities reflect intermediate-run
behavioral changes. In the long run, supply and demand are expected to be more elastic.
The estimated supply and demand elasticities were based on best data we could find. For
supply elasticities, we used the industry-level data published by the National Bureau of
Economic Research (NBER)-Center for Economic Studies (Bartlesman, Becker, and Gray,
2000). For demand elasticities, in addition to data from the NBER, we used the Current
Industrial Reports (CIR) series from the U.S. Census Bureau to produce an annual summary of
the production of motors and generators and a summary of production of several types of lawn
and garden equipment; both of these reports include the number of units manufactured and the
value of production (U.S. Census Bureau, 1998; 2000). For walk-behind lawnmowers, we used
several data series reported in a study by Air Improvement Resource, Inc., and National
Economic Research Associates (AIR/NERA, 2003). The U.S. Census Bureau publishes
historical data on household income and housing starts (U.S. Census Bureau, 2002; 2004), and
we collected price, wage, and material cost indexes from the Bureau of Labor Statistics (BLS,
2004a,b,c,d,e). In cases where a price index was not available, we used the most recent implicit
gross domestic product (GDP) price deflator reported by the U.S. Bureau of Economic Analysis
(BEA, 2004).13 It should be noted that the aggregate data we used to estimate elasticities include
data on other markets as well as the Small SI or Marine SI markets. If we had been able to
obtain market-specific data for Small SI or Marine SI only, the estimated price elasticities may
have been different.
Tables 9.3-21 and 9.3-22 provide a summary of the demand and supply elasticities used
to estimate the economic impact of the proposed rule.
The estimated supply elasticities for all of the equipment and engine markets are elastic,
ranging from 2.3 for all recreational marine except PWC, to 3.3 for generators, 3.4 for PWCs and
all Small SI applications except generators, and 3.8 for engines. This means that quantities
supplied are expected to be fairly sensitive to price changes (e.g., a 1 percent change in price
yields a 3.3 percent change in quantity of generators produced).
On the demand side, the Marine SI equipment market estimated demand elasticity is
elastic, at -2.0. This is consistent with the discretionary nature of purchases of recreational
marine vessels (consumers can easily decide to spend their recreational budget on other
alternatives).
The estimated demand elasticity for handheld equipment is elastic, at -1.9. This suggests
that consumers are more sensitive to price changes for handheld equipment than for other Small
SI equipment. In other words, they are more likely to change their purchase decision for a small
change in the price of a string trimmer, perhaps opting for trimmer shears or deciding to forego
trimming altogether.
13A11 values are expressed in 1987$. Note the GDP deflators have been updated since the original
estimation of supply elasticities for the Clean Air Nonroad Diesel rule. As a result, the elasticity estimation method
is the same; however, the coefficients may vary slightly.
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Draft Regulatory Impact Analysis
The estimated demand elasticity for lawnmowers is very inelastic at -0.2. This suggests
that consumers of this equipment are not very sensitive to price changes. Most of this equipment
is sold to individual homeowners, who are often required by local authorities to keep their lawns
trimmed. Household ownership of a gasoline lawnmower is often their least expensive option.
Lawncare services are more expensive since the price for these services includes labor and other
factors of production. Purchasing other equipment may also not be attractive, since electric and
diesel mowers are generally more expensive and often less convenient. Finally, the option of
using landscape alternatives (e.g., prairie, wildflower, or rock gardens) may not be attractive for
home homeowners who may also use their yards for recreational purposes. For all these reasons,
the price sensitivity of homeowners to lawnmower prices would be expected to be inelastic.
All the other demand elasticities, for gensets, welders, compressors, and agriculture/
construction equipment, are about unit elastic, at -1.0 meaning a 1 percent change in price is
expected to result in a 1 percent change in demand.
The demand elasticities for the engine markets are internally derived as part of the
process of running the model. This is an important feature of the EIM, which allows it to link
the engine and equipment components of each model and simulate how compliance costs can be
expected to ripple through the affected market. In actual markets, for example, the quantity of
lawnmowers produced in a particular period depends on the price of engines (the Small SI
engine market) and the demand for equipment by residential consumers. Similarly, the number
of engines produced depends on the demand for engines (the lawnmower market), which
depends on consumer demand for equipment. Changes in conditions in one of these markets will
affect the others. By designing the model to derive the engine demand elasticities, the EIM
simulates these connections between supply and demand among the product markets and
replicates the economic interactions between producers and consumers.
Because the elasticity estimates are a key input to the model, a sensitivity analysis for
supply and demand elasticity parameters was performed as part of this analysis in considering
the uncertainty involved in the estimated elasticities. The results are presented in Appendix 9H.
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Economic Impact Analysis
Table 9.3-21: Summary of Market Supply Elasticities Used in EIM
Market Estimate
Engine Markets 3 . 8
Small SI and Marine SI
Marine Equipment Markets
PWC 3.4
All other vessel types 2.3
Small SI Equipment Markets
Gensets/w elders 3 . 3
All other Small SI 3.4
equipment (handheld
and nonhandheld)
Source
EPA econometric
estimate
EPA econometric
estimate
EPA econometric
estimate
EPA econometric
estimate
EPA econometric
estimate
Method
Cobb-Douglas
production function
Cobb-Douglas
production function
Cobb-Douglas
production function
Cobb-Douglas
production function
Cobb-Douglas
production function
Input Data Source
Bartlesman et al
(2000); 1958-1996;
SIC 3519
Bartlesman et al
(2000); 1958-1996;
SIC 3799
Bartlesman et al
(2000); 1958-1996;
SIC 3732
Bartlesman et al
(2000); 1958-1996;
SIC 3621
Bartlesman et al
(2000); 1958-1996;
SIC 3524
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Draft Regulatory Impact Analysis
Table 9.3-22: Summary of Market Demand Elasticities Used in EIM
Market
Estimate Source
Method
Input Data Source
Engine Markets
Small SI and Marine SI
Derived Demand
Marine Equipment Markets
All vessel types -2.0
EPA econometric
estimate
Simultaneous
equation (3 SLS)
Bartlesman et al (2000);
1958-1996; SIC 3732
Small SI Equipment Markets
HANDHELD: All -1.9
NONHANDHELD
Lawn mowers
-0.2
Other lawn and garden -0.9
Gensets/welders - Class I -1.4
Gensets/welders - Class
II
-1.1
All other nonhandheld -1.0
EPA econometric
estimate
Simultaneous
equation (2SLS)
EPA econometric
estimate
EPA econometric
estimate
EPA econometric
estimate
EPA econometric
estimate
Simultaneous
equation (3 SLS)
Simultaneous
equation (2SLS)
Simultaneous
equation (2SLS)
Simultaneous
equation (2SLS)
EPA econometric Simultaneous
estimate equation (2SLS)
U.S. Census Bureau,
Current Industrial
Reports, MA333A 2000
and selected previous
years; 1980-1997
AIR/NERA (2003);
1973-2002
Bureau, Current
Industrial Reports,
MA333A 2000 and
selected previous years;
1980-1997
Bureau, Current
Industrial Reports,
MA333A 2000 and
selected previous years;
1980-1997
Bureau, Current
Industrial Reports,
MA333A 2000 and
selected previous years;
1980-1997
U.S. Census Bureau,
Current Industrial
Reports, MA333A 2000
and selected previous
years; 1980-1997
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Economic Impact Analysis
9.3.7 Economic Impact Model Structure
9.3.7.1 Computing Baseline and With-Regulation Equilibrium Conditions
The economic impact analysis is conducted using the data and the supply and demand
framework described above. The price and quantity data, along with the supply and demand
elasticities, are used to identify the market supply and demand curves. The regulatory costs are
then used to shift the supply curve, and the resulting new equilibrium determines the market
impacts and distribution of social impacts.
Figure 9.3-1 illustrates the economic impact modeling structure. Point A represents the
initial baseline equilibrium price and quantity (corresponding to the prices and quantities
presented in section 9.3.2). The slope of the supply and demand curves passing through the
baseline point A are determined by applying the appropriate supply and demand elasticities
presented in section 9.3.6. These slopes reflect the responsiveness of producers and consumers
when prices change and determine how much of the compliance costs producers are able to pass
along to consumers in the with-regulation equilibrium.
The compliance costs associated with the regulation (presented in Section 9.3.3) enter the
model expressed as per-unit costs and result in an upward shift in the supply curve from S0 to St
in Figure 9.3-1. Note that the demand curve does not shift because consumer preferences and
income are not affected by the regulation.
With the addition of the compliance costs, if prices were not allowed to adjust demanders
would still want to consume the quantity at point A, but suppliers would only be willing to
supply the quantity at point B (i.e., demand exceeds supply at the baseline price, P). The model
then solves for the new equilibrium price (P*) where the quantity demanded equals the quantity
supplied. The movement from the baseline equilibrium point A to with-regulation equilibrium
point C determines the market impacts (changes in price and quantity) as well as the distribution
of social costs. Appendix 9D describes the set of supply and demand equations included in the
model. Given the number of equations included in the model, the solution algorithm described
below is used to identify the new with-regulation set of equilibrium prices and quantities (Point
C).
The analysis illustrated in Figure 9.3-1 is repeated for each year included in the period of
analysis. For future years, a projected time series of prices and quantities are developed and
used as the baseline (point A) from which market changes are evaluated. The engineering cost
analysis provides quantities for future years using historical annual growth rates. In contrast,
there is much more uncertainty surrounding future prices for these markets. As a result, we use a
constant 2005 observed prices for the relevant markets during the period of analysis.
9.3.7.2 Solution Algorithm
Supply responses and market adjustments can be conceptualized as an interactive
process. Producers facing increased production costs due to compliance are willing to supply
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Draft Regulatory Impact Analysis
smaller quantities at the baseline price. This reduction in market supply leads to an increase in
the market price that all producers and consumers face, which leads to further responses by
producers and consumers and thus new market prices, and so on. The new with-regulation
equilibrium is the result of a series of iterations in which price is adjusted and producers and
consumers respond, until a set of stable market prices arises where total market supply equals
market demand. Market price adjustment takes place based on a price-revision rule, described
below, that adjusts price upward (downward) by a given percentage in response to excess
demand (excess supply).
The EIM model uses a similar type of algorithm for determining with-regulation
equilibria and the process can be summarized by six recursive steps:
1. Impose the control costs on affected supply segments, thereby affecting their
supply decisions.
2. Recalculate the market supply in each market. Excess demand currently exists.
3. Determine the new prices via a price revision rule. We use a rule similar to the
factor price revision rule described by Kimbell and Harrison (1986). P; is the
market price at iteration I, qd is the quantity demanded, and qs is the quantity
supplied. The parameter z influences the magnitude of the price revision and
speed of convergence. The revision rule increases the price when excess demand
exists, lowers the price when excess supply exists, and leaves the price unchanged
when market demand equals market supply. The price adjustment is expressed as
follows:
(10.1)
4. Recalculate market supply with new prices,
5. Compute market demand in each market.
6. Compare supply and demand in each market. If equilibrium conditions are not
satisfied, go to Step 3, resulting in a new set of market prices. Repeat until
equilibrium conditions are satisfied (i.e., the ratio of supply and demand is
arbitrarily close to one). When the ratio is appropriately close to one, the
market-clearing condition of supply equals demand is satisfied.
9.3.7.3 Estimating Impacts
Using the static partial equilibrium analysis, the EIM model loops through each year
calculating new market equilibriums based on the projected baseline economic conditions and
compliance cost estimates that shift the supply curves in the model. The model calculates price
and quantity changes and uses these measures to estimate the social costs of the rule and
partition the impact between producers and consumers.
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9.4 Methods for Describing Uncertainty
Every economic impact analysis examining the market and social welfare impacts of a
regulatory program is limited to some extent by limitations in model capabilities, deficiencies in
the economic literatures with respect to estimated values of key variables necessary to configure
the model, and data gaps. In this EIA, there are three main potential sources of uncertainty: (1)
uncertainty resulting from the way the EIM is designed, particularly from the use of a partial
equilibrium model; (2) uncertainty resulting from the values for key model parameters,
particularly the price elasticity of supply and demand; and (3) uncertainty resulting from the
values for key model inputs, particularly baseline equilibrium price and quantities. Sources of
uncertainty that have a bearing on the results of the EIA for the proposed program are listed and
described in more detail in Table 9.4-1.
The values used for the price elasticities of supply and demand are critical parameters in
the EIM. The values of these parameters have an impact on both the estimated change in price
and quantity produced expected as a result of compliance with the proposed standards and on
how the burden of the social costs will be shared among producer and consumer groups. In
selecting the values to use in the EIM it is important that they reflect the behavioral responses of
the industries under analysis.
The first source of values for elasticities of supply and demand is the published economic
literature. These estimates are peer reviewed and generally constitute reasonable estimates for
the industries in question. In this analysis, because we were unable to find published supply and
demand elasticities for the Small SI and Marine SI markets, we estimated these parameters
econometrically using the procedures described in Appendix 9E.
The estimates of supply elasticities reflect a production function approach using data at
the aggregate industry level. This method was chosen because of limitations with the available
data: we were not able to obtain firm-level or plant-level production data for companies that
operate in the affected sectors. However, the use of aggregate industry level data may not be
appropriate or an accurate way to estimate the price elasticity of supply compared to firm-level
or plant-level data. This is because, at the aggregate industry level, the size of the data sample is
limited to the time series of the available years and because aggregate industry data may not
reveal each individual firm or plant production function (heterogeneity). There may be
significant differences among the firms that may be hidden in the aggregate data but that may
affect the estimated elasticity. In addition, the use of time series aggregate industry data may
introduce time trend effects that are difficult to isolate and control.
To address these concerns, EPA intends to investigate estimates for the price elasticity of
supply for the affected industries for which published estimates are not available, using
alternative methods and data inputs. This research program will use the cross-sectional data
model at either the firm-level or plant level from the U.S. Census Bureau to estimate these
elasticities. We plan to use the results of this research provided the results are robust and that
they are available in time for the analysis for the final rule.
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Table 9 .4-1 Primary Sources of Uncertainty in the Economic Impact Analysis
Source of Uncertainty Description Potential Impact
UNCERTAINTIES ASSOCIATED WITH ECONOMIC IMPACT MODEL STRUCTURE
Partial equilibrium
model
The EIM domain is limited to the economic sectors
directly affected by the emission control program;
impacts on secondary markets are not accounted for.
However, such impacts are not expected to be large
since directly affected products and services (small SI
equipment and marine SI vessels) are mostly used by
households and only a very small portion of these
engines and equipment are used as production inputs
to other industry (e.g., agriculture, manufacturing,
construction). In addition, Small SI engines and
equipment would not be a large share of total
production costs for final goods and services in those
commercial markets.
Results understate social
costs; magnitude of impact is
uncertain.
National level model
The EIM considers only national-level impacts;
regional impacts are not modeled. This is appropriate
because Small SI engine and equipment or Marine SI
engine and vessel markets are national markets.
While there may be some regional differences these
are likely to be small due to the competitive nature of
the manufacture industry.
Impacts uncertain
Supply side
assumptions
On the supply side, industries are assumed to be
mature and behave linearly within the range of
analysis; no substitution between production inputs.
This is appropriate because per unit compliance costs
are not large enough to prompt a major change in
product design or assembly.
Impacts uncertain
Demand side
assumption
On the demand side, end consumer's preferences or
consumption patterns are assumed to be constant and
behave linearly within the range of analysis. This is
appropriate because all other factors in the demand
function will not be changed by the proposed rule.
Impacts uncertain
Constant price
assumption
Prices are assumed to be constant across the period of
analysis. This is a reasonable assumption since it is
not possible to predict changes in these prices over
time (see Appendix G).
Impacts uncertain
Period of analysis
Each period of analysis is assumed to be independent
of previous period and producers are assumed to not
engage in long-term planning to smooth the
compliance costs over a longer period of time.
Because the new exhaust standards will not go into
effect for several years after the program is finalized,
producers may in fact take the full program into
account in production plans to minimize their costs.
Estimated price changes may
be too high for early periods,
too low for later periods;
magnitude of impact is
uncertain
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Economic Impact Analysis
Market shock
In the EIM, the market is shocked by the full
compliance costs, including variable and fixed costs.
This is appropriate because producers in these
industries may not engage in R&D on a continuous
basis and thus the product changes that would be
required to comply with the proposed standards
would require manufacturers to devote new funds and
resources to product redesign. A sensitivity analysis
performed that excludes fixed costs in supply shift.
Results may overstate
distribution of social costs to
some producers, understate
market impacts; magnitude of
impact is uncertain
Sensitivity analysis performed
UNCERTAINTIES ASSOCIATED WITH PRICE ELASTICITY ESTIMATION
Uncertainty resulting from the functional form used
in the estimation, the data used (aggregate or
firm-level), the time period involved, sample size.
Impacts on distribution of
social costs among
stakeholders (e.g., higher
supply elasticity would result
in less social costs for
manufacturers and more
social costs for consumers)
Impacts on market analysis
(change in price, change in
quantity produced)
Magnitude of impact is
uncertain
Sensitivity analysis performed
UNCERTAINTIES ASSOCIATED WITH DATA INPUTS
Submarket groupings
Baseline equilibrium
prices
Baseline equilibrium
quantities
Submarket data is assumed to be representative and
capture the range of affected equipment. However,
the product groupings in NAICS or SIC 4-digit
categories may include other engines or equipment
that may not have the same production or
consumption characteristics; these groupings not
behave the same way as the directly -affected
industries.
Estimated baseline equilibrium prices are assumed to
be representative and capture the range of affected
equipment, and reflect actual transaction prices.
However, the actual prices paid by consumers may be
different. Also, the mix of products included in price
analysis may not be representative of the population.
Estimated baseline equilibrium quantities and future
quantities assumed to be representative; these are the
same as the cost analysis.
Impacts on social welfare and
market analyses uncertain
Impacts on market analysis
uncertain
Impacts on market analysis
uncertain
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Draft Regulatory Impact Analysis
To explore the effects of key sources of uncertainty, we performed a sensitivity analysis
in which we examine the results of using alternative values for the price elasticity of supply and
demand (using the upper and lower bound of at 95 percent confidence interval around the point
estimate for each elasticity estimate), alternative methods to shock to the market equilibrium
(using variable costs only) and alternative baseline equilibrium prices for lawnmowers and
tractors. The results of these analyses are contained in Appendix 9H. A summary of the results
are presented in Table 9.4-2.
Table 9.4-2. Results of Sensitivity Analysis
Parameter
Year
Change in Value
Impact
Price
Elasticity of
Supply
2013
More elastic
(upper bound of
95 percent
confidence
interval for each
elasticity
estimate)
Negligible impact on expected price increase and quantity
decrease (less than 0.2 additional increase in price increase
compared to primary analysis; less than 0.2 additional increase in
quantity decrease compared to primary analysis)
More elasticity price elasticity of supply associated with increase
in social cost burden for users of Small SI and Marine SI engines
and equipment (shift of about 1.4 percent of burden of compliance
costs from producers to consumers in Marine SI market; shift of
about 2.0 percent of burden of compliance costs from producers to
consumers in Small SI market)
2013
Less Elastic
(lower bound of
95 percent
confidence
interval for each
elasticity
estimate)
Negligible impact on expected price increase and quantity
decrease (less than 0.1 additional increase in price increase
compared to primary analysis; less than 0.2 percent additional
increase in quantity decrease compared to primary analysis)
Higher value associated with increase in social cost burden for
producers of Small SI and Marine SI engines and equipment (shift
of about 1.3 percent of burden of compliance costs from
consumers to producers in Marine SI market; shift of about 1.9
percent of burden of compliance costs from consumers to
producers in Small SI market)
Price
Elasticity of
Demand
2013
More Elastic
(upper bound of
95 percent
confidence
interval for each
elasticity
estimate)
Negligible impact on expected price increase and quantity
decrease (less than 1.0 percent additional increase in price
increase compared to primary analysis; less than 1.5 additional
increase in quantity decrease, compared to primary analysis)
More elastic price elasticity of demand associated with increase
in social cost burden for producers of Small SI and Marine SI
engines and equipment (shift of about 11 percent of burden of
compliance costs from consumers to producers in Marine SI
market; shift of about 10 percent of burden of compliance costs
from consumers to producers in Small SI market)
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Economic Impact Analysis
2013 Less Elastic
(lower bound of
95 percent
confidence
interval for each
elasticity
estimate)
Negligible impact on expected price increase and quantity
decrease (less than 2.0 percent additional increase in price
increase compared to primary analysis; less than 2.5 additional
increase in quantity decrease, compared to primary analysis)
Less elastic price elasticity of demand associated with increase in
social cost burden for users of Small SI and Marine SI engines and
equipment (shift of about 30.5 percent of burden of compliance
costs from producers to consumers in Marine SI market; shift of
about 14.5 percent of burden of compliance costs from producers
to consumers in Small SI market)
Market
Supply Shift
2013
Include only
variable costs
Smaller projected price increases and quantity decreases (less than
1.5 percent additional increase in price compared to primary
analysis; less than 1.0 percent additional increase in quantity
decrease, compared to primary analysis)
Engine and equipment manufacturers expected to bear larger share
of total compliance costs (shift of about 3.1 percent of burden of
compliance costs from consumers to producers in Marine SI
market; shift of about 16.2 percent of burden of compliance costs
from consumers to producers in Small SI market)
Alternative
Baseline
Equilibrium
Price -
Lawnmowers
and Tractors
2013 Lower baseline
equilibrium price
Larger percent increase in price and percent decrease in quantity,
although absolute changes are smaller (about 2 percent additional
price increase for both sectors compared to primary analysis;
about 0.4 percent additional quantity decrease for lawn mowers
and about 1.9 percent additional quantity decrease for tractors
compared to primary analysis)
Social welfare impacts unchanged.
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Chapter 9 References
Air Improvement Resource, Inc. and National Economic Research Associates, Inc. (AIR/NERA). 2003. "Cost-
Effectiveness Analyses of Alternative California Air Resources Board Tier 3 Non-Handheld Exhaust Emission
Proposals." Prepared for Engine Manufacturers Association and Outdoor Power Equipment Institute. Docket
IdentificationEPA-HQ-OAR-2004-0008-0458
Allen, R.G.D. 1938. Mathematical Analysis for Economists. New York: St. Martin's Press.
Baumol, William. "Contestable Markets: An Uprising in the theory of Industry Structure,"
American Economic Review, 72, March 1982:1-15.
Baumol, William, John Panzer, and Robert Willig. 1982. Contestable Markets and the Theory of
Industry Structure, San Diego, CA: Harcourt, Brace, Jovanovich.
Berck, P., and S. Hoffmann. 2002. "Assessing the Employment Impacts." Environmental and
Resource Economics 22:133-156.
Bingham, T.H., and TJ. Fox. 1999. "Model Complexity and Scope for Policy Analysis."
Public Administration Quarterly 23(3).
Caffrey, C, and Cle Jackson, Zuimdie Guerra. September 2006. Memorandum to Docket EPA-HQ-OAR-2004-0008
Re: Small SI Engine Sales and Price Estimates. A copy of this document is available in Docket EPA-HQ-OAR-
2004-0008. Docket Identification EPA-HQ-OAR-2004-0008-0491.
Fullerton, D., and G. Metcalf. 2002. "Tax Incidence." In A. Auerbach and M. Feldstein, eds., Handbook of Public
Economics, Vol.4, Amsterdam: Elsevier.
Harberger, Arnold C. 1974. Taxation and Welfare. Chicago: University of Chicago Press.
Hicks, J.R., 1961. Marshall's Third Rule: A Further Comment. Oxford Economic Papers
13:262-65. Docket Identification EPA-HQ-OAR-2004-0008-0459
Hicks, J.R., 1966. The Theory of Wages. 2nd Ed. New York: St. Martins Press, pp. 233-247.
Docket Identification EPA-HQ-OAR-2004-0008-0460
Kimbell, L.J., and G. W. Harrison. 1986. "On the Solution of General Equilibrium Models."
Economic Modeling 3:197-212.
Li, Chi. March 16, 2007. Memorandum to Docket EPA-HQ-OAR-2004-0008 Detailed Results From Economic
Impact Model.
NBER-CES. National Bureau of Economic Research and U.S. Census Bureau, Center for
Economic Research. 2002. NBER-CES Manufacturing Industry Database, 1958 -1996.
http ://www. nber. org/nberces/nbprod96 .htm
Nicholson, W. 1998. Microeconomic Theory: Basic Principles and Extensions. Fort Worth: Dryden Press.
Office Management and Budget (OMB). 1996. Executive Analysis of Federal Regulations
Under Executive Order 12866. Executive Office of the President, Office Management and
Budget. January 11, 1996. A copy of this document is available at
http://www.whitehouse.gov/omb/inforeg/print/riaguide.html.
9-68
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Economic Impact Analysis
Outdoor Power Equipment & Engine Service Association. OPE-IN-THE-KNOW, Volume LXXIV, December 30,
2004. "The Business of Outdoor Power Equipment". Docket Identification EPA-HQ-OAR-2004-0008-0478.
Raboy, David. 1987. "Results of an Economic Analysis of Proposed Excise Taxes on Boats." Washington, DC.
Docket Identification EPA-HQ-OAR-2004-0008-0462.
RTI International (RTI). 2005. "Economic Impact Analysis (EIA) for Additional Tier of Emissions Standards for
Nonroad Spark Ignition Engines and Equipment: Revised Draft Analysis Plan." EPA Contract No. 68-D-99-024.
Docket Identification EPA-HQ-OAR-2004-0008-0463.
RTI International (RTI). 2006a. "Draft Industry Profile for Recreational Marine Industry." Research Triangle Park,
NC: RTI. EPA Contract No. 68-D-99-024. Docket Identification EPA-HQ-OAR-2004-0008-0492
RTI International (RTI). 2006b. "Draft Industry Profile for Small Nonroad Spark-Ignition Engines and Equipment."
Research Triangle Park, NC: RTI. EPA Contract No. 68-D-99-024. Docket Identification EPA-HQ-OAR-2004-
0008-0469.
RTI International (RTI). 2006c. "Memorandum on Calculation Motor Gasoline Prices in Small SI rule EIA". EPA
Contract No. 68-D-99-024. A copy of this document is available in EPA-HQ-OAR-2004-0008. Docket
IdentificationEPA-HQ-OAR-2004-0008-0449.
Samulski, M. August 2004. Memorandum to Docket EPA-HQ-OAR-2004-0008 Re: Draft Marine SI Sales and
Prices Estimates. Docket Identification EPA-HQ-OAR-2004-0008-0448.
U.S. Bureau of Economic Analysis. 2004. Table 1.1.9, Implicit Price Deflators for Gross Domestic Product. Last
revised April 29, 2004. Docket Identification EPA-HQ-OAR-2004-0008-0473.
U.S. Bureau of Labor Statistics. 2004a. Producer Price Index Industry Data: (1) Plastic Material and Resins
Manufacturing. Series ID: PCU325211325211 (May 14, 2004), (2) Consumer Nonriding Lawn, Garden, and Snow
Equipment. Series ID: PCU3331123331121 (May 20, 2004), (3) Other Engine Equipment Manufacturing. Series ID:
PCU3336183336181 (May 20, 2004), (4) Rotary, Push Type Gasoline Engine Powered. Series ID: WPU12660201 (
August 10, 2004). A copy of this document is available in the Docket. Docket Identification EPA-HQ-OAR-2004-
0008-0474.
U.S. Bureau of Labor Statistics. 2004b. Average Hourly Earnings of Production Workers (Boat Building: Series ID
CEU3133661206; Farm Machinery and Equipment: Series ID EEU31352306). Obtained May 18, 2004. Docket
IdentificationEPA-HQ-OAR-2004-0008-0474.
U.S. Census Bureau. 1998 and selected other previous years. Current Industrial Reports. Motors and Generators.
MA335H (MA36H prior to 1998). Washington, DC: U.S. Government Printing Office. Docket Identification EPA-
HQ-OAR-2004-0008-0475.
U.S. Census Bureau. 2000 and selected other previous years. Current Industrial Reports. Farm Machinery and Lawn
and Garden Equipment. MA333A (MA35A prior to 1998). Washington, DC: U.S. Government Printing Office.
Docket Identification EPA-HQ-OAR-2004-0008-0476.
U.S. Census Bureau. 2005. Survey of Plant Capacity: 2004. Current Industrial Reports MQ-C1(04). Table 1. A
copy of this document can be found at . Table la.
U.S. Department of Energy, Energy Information Administration. 2006. "Petroleum Marketing Annual 2005." A
copy of this document can be found at
http://www.eia.doe.gov/oil_gas/petroleum/data_publications/petroleum_marketing_annual/pma.html. Table 31.
U.S. Environmental Protection Agency. 1999. OAQPS Economic Analysis Resource Document.
9-69
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Draft Regulatory Impact Analysis
Research Triangle Park, NC: EPA. A copy of this document can be found at
http://www.epa.gov/ttn/ecas/econdata/6807-305.pdf.
U.S. Environmental Protection Agency. 2000. Guidelines for Preparing Economic Analyses.
EPA-240-R-00-003, September 2000.
U.S. Environmental Protection Agency. 2004. Final Regulatory Analysis: Control of Emissions from Nonroad
Diesel Engines. EPA-420-R-04-007. Research Triangle Park, NC: EPA.
9-70
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Economic Impact Analysis
Appendix 9A: Impacts on Small SI Markets
This appendix provides the time series of impacts from 2008 through 2038 for the
following Small SI engines and equipment markets; a complete set of results for all markets can
be found in the docket for this rule (Li, 2007). Results are presented for equipment in the Class I
UL125 and Class IIUL250 categories because those are the categories with the highest sales.
• Class I engines
• Class II engines
Agriculture/construcion/general industrial, UL125 and UL250
Utility and recreational vehicles, UL125 and UL250
• Lawn mowers, UL125
Tractors, UL250
• Lawn and garden other, UL125 and UL250
• Gensets/welders, UL125 and 250
• Pumps/compressors, pressure washers, UL125 and UL250
Snowblowers, UL125 and UL250
Table 9A-1 through Table 9 A-17 provide the time series of impacts for each engine class
market and each selected equipment market, respectively, includes the following:
• average engine or equipment price
• average engineering costs (variable and fixed) per engine or equipment
• absolute change in the market price ($)
• relative change in market price (%)
relative change in market quantity (%)
total engineering costs associated with each engine or equipment market
changes in producer surplus associated with each engine or equipment market
All prices and costs are presented in 2005 dollars and real engine or equipment prices are
assumed to be constant during the period of analysis. Net present values were estimated using
social discount rates of 3 percent and 7 percent over the period of analysis.
9-71
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Draft Regulatory Impact Analysis
Table 9A-1 : Impact on Small SI Engine Market
Class I (Average Price per Engine = $130)a
Small SI Engine (Class I)
Engineering
Year Cost/Unit
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
$0
$0
$0
$0
$15
$15
$15
$15
$15
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
$12
Absolute
Change in
Price
$0
$0
$0
$0
$14
$14
$14
$14
$14
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
Change in Change in
Price Quantity
(%) (%)
0.3% 0.0%
0.3% 0.0%
0.3% 0.0%
0.3% 0.0%
10.9% -2.0%
10.7% -2.0%
10.7% -2.0%
10.7% -2.0%
10.7% -2.0%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
8.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
.6%
Total
Engineering
Costs
(million $)
$0.0
$3.6
$3.7
$3.7
$161.9
$162.8
$165.4
$167.8
$170.2
$139.0
$141.2
$143.4
$145.6
$147.7
$149.9
$152.1
$154.3
$156.5
$158.7
$160.9
$163.1
$165.3
$167.5
$169.7
$171.9
$174.1
$176.3
$178.5
$180.7
$182.9
$185.2
$2,630.8
$1,466.2
Change in Engine
Manufacturers
Surplus
(million $)
-$0.2
-$0.2
-$0.2
-$0.2
-$7.3
-$7.4
-$7.5
-$7.6
-$7.7
-$6.3
-$6.4
-$6.5
-$6.6
-$6.7
-$6.8
-$6.9
-$7.0
-$7.1
-$7.2
-$7.3
-$7.4
-$7.5
-$7.6
-$7.7
-$7.8
-$7.9
-$7.9
-$8.1
-$8.2
-$8.3
-$8.4
-$119.5
-$66.7
Figures are in 2005 dollars.
9-72
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Economic Impact Analysis
Table 9A-2. Impact on Small SI Engine Market
Class II (Average Price per Engine = $290)a
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
Engineering
Cost/Unit
$0
$0
$0
$42
$42
$42
$42
$42
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
$29
Small
Absolute
Change in
Price
$0
$0
$0
$40
$40
$40
$40
$40
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
$28
SI Engine (Class II)
Change in
Price
(%)
0.0%
0.0%
0.0%
14.0%
13.9%
13.9%
13.9%
13.8%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
10.1%
Change in
Quantity
(%)
-0.1%
-0.1%
-0.1%
-3.1%
-3.1%
-3.1%
-3.0%
-3.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
Total
Engineering
Costs
(million $)
$0.0
$0.0
$0.0
$202.2
$205.2
$208.3
$211.3
$214.3
$152.7
$155.1
$157.6
$160.1
$162.5
$165.0
$167.4
$169.9
$172.4
$174.8
$177.3
$179.8
$182.3
$184.7
$187.2
$189.7
$192.2
$194.7
$197.1
$199.6
$202.1
$204.6
$207.0
$3,164.8
$1,828.9
Change in Engine
Manufacturers
Surplus
(million $)
-$0.2
-$0.2
-$0.2
-$10.8
-$10.9
-$11.0
-$11.2
-$11.3
-$7.3
-$7.4
-$7.5
-$7.6
-$7.8
-$7.9
-$8.0
-$8.1
-$8.2
-$8.3
-$8.5
-$8.6
-$8.7
-$8.8
-$8.9
-$9.1
-$9.2
-$9.3
-$9.4
-$9.5
-$9.7
-$9.8
-$9.9
-$156.3
-$91.5
Figures are in 2005 dollars.
9-73
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Draft Regulatory Impact Analysis
Table 9A-3 : Impact on Small SI Equipment Market
Handheld (Average Price per Equipment = $87)a'b
Small SI Equipment (Handheld)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Absolute
Engineering Change in
Cost/Unit Price
$0
$0
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$1
$0
$0
$1
$1
$1
$1
$1
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
2005 dollars.
per equipment for the market
Total
Change Change in Engineering Change in Equipment
in Price Quantity Costs Manufacturers Surplus
(%) (%) (millions) (million $)
0.0% 0.0%
0.0% 0.0%
0.6%
0.6%
0.6%
0.6%
0.6%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
.1%
.1%
.1%
.1%
.1%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
is a weighted average
$0.0
$0.0
$7.3
$7.4
$7.5
$7.7
$7.8
$6.7
$6.8
$6.9
$7.0
$7.1
$7.2
$7.4
$7.5
$7.6
$7.7
$7.8
$7.9
$8.0
$8.1
$8.2
$8.3
$8.4
$8.5
$8.7
$8.8
$8.9
$9.0
$9.1
$9.2
$139.9
$81.3
of the price of equipment by
$0.0
$0.0
-$2.6
-$2.6
-$2.7
-$2.7
-$2.8
-$2.4
-$2.4
-$2.5
-$2.5
-$2.6
-$2.6
-$2.6
-$2.7
-$2.7
-$2.7
-$2.8
-$2.8
-$2.9
-$2.9
-$2.9
-$3.0
-$3.0
-$3.1
-$3.1
-$3.1
$o ^
3.2
$o *•>
3.2
-$3.2
-$3.3
-$49.9
-$29.0
hp.
9-74
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Economic Impact Analysis
Table 9A-4: Impact on Small SI Equipment Market: Class I Ag/Constr./Gen. Ind/ Material
Handling Equipment UL 125 (Average Price per Equipment = $l,108)a'b
Class 1 Agricultural/Construction/General Industrial/ Material
Handling Equipment UL 125
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Engineering
Cost/Unit
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
Absolute
Change in
Price
$0
$0
$0
$0
$12
$12
$12
$12
$12
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
2005 dollars.
per equipment for the market
Change
in Price
(%)
0.0%
0.0%
0.0%
0.0%
1.1%
1.1%
1.1%
1.1%
1.1%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
is a wei|
Total
Change in Engineering Change in Equipment
Quantity Costs Manufacturers Surplus
(%) (million $) (million $)
0.0%
0.0%
0.0%
0.0%
-1.1%
-1.1%
-1.1%
-1.1%
-1.1%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
jhted average
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
of the price of equipment by
$0.0
$0.0
$0.0
$0.0
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.2
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$4.8
-$2.7
hp.
9-75
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Draft Regulatory Impact Analysis
Table 9A-5:
Impact on Small SI Equipment Market: Class I Utility and Recreational Vehicles
UL 125 (Average Price per Equipment = $570)a'b
Small SI Equipment (Class
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Engineering
Cost/Unit
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
Absolute
Change in
Price
$0
$0
$0
$0
$12
$12
$12
$12
$12
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
2005 dollars.
per equipment for the market
I Utility
125)
Change
in Price
(%)
0.0%
0.0%
0.0%
0.0%
2.1%
2.0%
2.0%
2.0%
2.0%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
1.6%
is a wei|
and Recreational Vehicles UL
Total
Change in Engineering Change in Equipment
Quantity Costs Manufacturers Surplus
(%) (million $) (million $)
0.0%
0.0%
0.0%
0.0%
-2.1%
-2.0%
-2.0%
-2.0%
-2.0%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
-1.6%
jhted average
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
of the price of equipment by
$0.0
$0.0
$0.0
$0.0
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.3
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$5.1
-$2.8
hp.
9-76
-------
Economic Impact Analysis
Table 9A-6
: Impact on Small SI Equipment Market: Class I Lawn Mowers UL 125 (Average
Price per Equipment = $218)a'b
Small SI Equipment
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Engineering
Cost/Unit
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
2005 dollars.
per equipment
Absolute
Change in
Price
$0
$0
$0
$0
$14
$14
$14
$14
$14
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
$11
for the market
(Class I
Change
in Price
(%)
0.1%
0.1%
0.1%
0.1%
6.6%
6.6%
6.6%
6.6%
6.5%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
5.2%
Lawn Mowers
Change in
Quantity
(%)
0.0%
0.0%
0.0%
0.0%
-1.3%
-1.2%
-1.2%
-1.2%
-1.2%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
-1.0%
UL 125)
Total
Engineering
Costs
(million $)
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
Change in Equipment
Manufacturers Surplus
(million $)
-$0.1
-$0.1
-$0.1
-$0.1
-$5.4
-$5.4
-$5.5
-$5.6
-$5.7
-$4.6
-$4.7
-$4.8
-$4.8
-$4.9
-$5.0
-$5.1
-$5.1
-$5.2
-$5.3
-$5.4
-$5.4
-$5.5
-$5.6
-$5.6
-$5.7
-$5.8
-$5.9
-$5.9
-$6.0
-$6.1
-$6.2
-$87.6
-$48.8
is a weighted average of the price of equipment by hp.
9-77
-------
Draft Regulatory Impact Analysis
Table 9A-7: Impact on Small SI Equipment Market: Class I Other Lawn and Garden Equipment
UL 125 (Average Price per Equipment = $245)a'b
Small SI Equipment (Class
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Absolute
Engineering Change in
Cost/Unit Price
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$12
$12
$12
$12
$12
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
2005 dollars.
per equipment for the market
I Other Lawn and Garden Equipment
UL 125)
Change
in Price
(%)
0.1%
0.1%
0.1%
0.1%
4.9%
4.9%
4.9%
4.9%
4.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
3.9%
is a wei|
Total
Change in Engineering Change in Equipment
Quantity Costs Manufacturers Surplus
(%) (million $) (million $)
-0.1%
-0.1%
-0.1%
-0.1%
-4.4%
-4.4%
-4.4%
-4.4%
-4.4%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
-3.5%
jhted average
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
of the price of equipment by
-$0.1
-$0.1
-$0.1
-$0.1
-$2.3
-$2.3
-$2.4
-$2.4
-$2.4
-$2.0
-$2.0
-$2.0
-$2.1
-$2.1
-$2.1
-$2.2
-$2.2
-$2.2
-$2.3
-$2.3
-$2.3
-$2.4
-$2.4
-$2.4
-$2.5
-$2.5
-$2.5
-$2.5
-$2.6
-$2.6
-$2.6
-$37.7
-$21.1
hp.
9-78
-------
Economic Impact Analysis
Table 9A-8:
Impact on Small SI Equipment Market: Class I Gensets/Welders UL 125 (Average
Price per Equipment = $999)a'b
Small SI Equipment (Class I Gensets/Welders UL 125)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Engineering
Cost/Unit
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
2005 dollars.
per equipment
Absolute
Change in
Price
$0
$0
$0
$0
$11
$11
$11
$11
$11
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
for the market
Change
in Price
(%)
0.0%
0.0%
0.0%
0.0%
1.1%
1.1%
1.1%
1.1%
1.1%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
0.9%
Total
Change in Engineering Change in Equipment
Quantity Costs Manufacturers Surplus
(%) (million $) (million $)
0.0%
0.0%
0.0%
0.0%
-1.5%
-1.5%
-1.5%
-1.5%
-1.5%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
is a weighted average
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
of the price of equipment by
$0.0
$0.0
$0.0
$0.0
-$1.4
-$1.4
-$1.4
-$1.4
-$1.4
-$1.2
-$1.2
-$1.2
-$1.2
-$1.2
-$1.3
-$1.3
-$1.3
-$1.3
-$1.3
-$1.4
-$1.4
-$1.4
-$1.4
-$1.4
-$1.5
-$1.5
-$1.5
-$1.5
-$1.5
-$1.5
-$1.6
-$22.1
-$12.3
hp.
9-79
-------
Draft Regulatory Impact Analysis
Table 9A-9: Impact on Small SI Equipment Market: Class I Pumps/Compressors/Pressure
Washers UL 125 (Average Price per Equipment = $96)a'b
Small SI Equipment (Class I Pumps/Compressors/Pressure
Washers UL 125)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Engineering
Cost/Unit
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
Absolute
Change in
Price
$0
$0
$0
$0
$12
$12
$12
$12
$12
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
$9
2005 dollars.
per equipment for the market
Change
in Price
(%)
0.3%
0.3%
0.3%
0.3%
12.3%
12.2%
12.2%
12.1%
12.1%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
9.7%
is a weig
Total
Change in Engineering Change in Equipment
Quantity Costs Manufacturers Surplus
(%) (million $) (million $)
-0.3%
-0.3%
-0.3%
-0.3%
-12.3%
-12.2%
-12.2%
-12.1%
-12.1%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
-9.7%
;hted average
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
of the price of equipment by
-$0.1
-$0.1
-$0.1
-$0.1
-$2.2
-$2.2
-$2.2
-$2.2
-$2.3
-$1.9
-$1.9
-$1.9
-$2.0
-$2.0
-$2.0
-$2.0
-$2.1
-$2.1
-$2.1
-$2.2
-$2.2
-$2.2
-$2.3
-$2.3
-$2.3
-$2.3
-$2.4
-$2.4
-$2.4
-$2.5
-$2.5
-$35.6
-$19.9
hp.
9-80
-------
Economic Impact Analysis
Table 9 A- 10
: Impact on Small SI Equipment Market: Class I Snowblowers UL 125 (Average
Price per Equipment = $324)a'b
Small
Engineering
Year Cost/Unit
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
SI Equipment (Class I Snowblowers UL 125)
Absolute
Change in
Price
$0
$0
$0
$0
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
$2
Change
in Price
(%)
0.1%
0.1%
0.1%
0.1%
0.7%
0.7%
0.7%
0.7%
0.7%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
Total
Change in Engineering Change in Equipment
Quantity Costs Manufacturers Surplus
(%) (million $) (million $)
-0.1%
-0.1%
-0.1%
-0.1%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
-0.5%
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
$0.0
-$0.1
-$0.1
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.3
-$0.3
-$0.3
-$0.3
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$0.4
-$6.4
-$3.6
a Figures are in 2005 dollars.
b Average price per equipment for the market is a weighted average of the price of equipment by hp.
9-81
-------
Draft Regulatory Impact Analysis
Table 9A-1 1 : Impact on Small SI Equipment Market: Class II Agri/Constr./G. Ind/ Material
Handling Equipment UL 250 (Average Price per Equipment = $l,825)a'b
Small SI Equipment (Class II Agricultural/Construction /General
Industrial/ Material Handling Equipment UL 250)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Absolute Change
Engineering Change in in Price
Cost/Unit Price (%)
$0
$1
$1
$12
$11
$11
$11
$11
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$1 0.0%
$1 0.0%
$1 0.0%
$35
$35
$35
$35
$35
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
.9%
.9%
.9%
.9%
.9%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
2005 dollars.
per equipment for the market is a wei|
Total
Change in Engineering Change in Equipment
Quantity Costs Manufacturers Surplus
(%) (million $) (million $)
0.0%
0.0%
0.0%
-1.9%
-1.9%
-1.9%
-1.9%
-1.9%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
jhted average
$0.0
$0.1
$0.1
$0.9
$0.9
$0.9
$0.9
$0.9
$0.5
$0.5
$0.5
$0.6
$0.6
$0.6
$0.6
$0.6
$0.6
$0.6
$0.6
$0.6
$0.6
$0.6
$0.6
$0.7
$0.7
$0.7
$0.7
$0.7
$0.7
$0.7
$0.7
$11.9
$7.1
of the price of equipment by
$0.0
$0.0
$0.0
-$0.8
-$0.8
-$0.9
-$0.9
-$0.9
-$0.6
-$0.6
-$0.6
-$0.7
-$0.7
-$0.7
-$0.7
-$0.7
-$0.7
-$0.7
-$0.7
-$0.7
-$0.7
-$0.8
-$0.8
-$0.8
-$0.8
-$0.8
-$0.8
-$0.8
-$0.8
-$0.8
-$0.8
-$12.9
-$7.6
hp.
9-82
-------
Economic Impact Analysis
Table 9A-12: Impact on Small SI Equipment Market: Class II Utility and Recreational Vehicle
UL 250 (Average Price per Equipment = $2,894)a'b
Small SI Equipment (Class
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Engineering
Cost/Unit
$0
$1
$1
$12
$11
$11
$11
$11
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
Absolute
Change in
Price
$1
$1
$1
$35
$35
$35
$35
$35
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
2005 dollars.
per equipment for the market
II Utility and Recreational Vehicle UL
250)
Change
in Price
(%)
0.0%
0.0%
0.0%
1.2%
1.2%
1.2%
1.2%
1.2%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
0.8%
is a wei|
Total
Change in Engineering Change in Equipment
Quantity Costs Manufacturers Surplus
(%) (million $) (million $)
0.0%
0.0%
0.0%
-1.2%
-1.2%
-1.2%
-1.2%
-1.2%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
jhted average
$0.0
$0.2
$0.2
$2.2
$2.3
$2.3
$2.3
$2.3
$1.3
$1.3
$1.3
$1.3
$1.4
$1.4
$1.4
$1.4
$1.5
$1.5
$1.5
$1.5
$1.5
$1.6
$1.6
$1.6
$1.6
$1.6
$1.7
$1.7
$1.7
$1.7
$1.7
$29.2
$17.5
of the price of equipment by
-$0.1
-$0.1
-$0.1
-$2.0
-$2.0
-$2.1
-$2.1
-$2.1
-$1.5
-$1.5
-$1.6
-$1.6
-$1.6
-$1.6
-$1.7
-$1.7
-$1.7
-$1.7
-$1.8
-$1.8
-$1.8
-$1.8
-$1.9
-$1.9
-$1.9
-$1.9
-$2.0
-$2.0
-$2.0
-$2.0
-$2.1
-$31.7
-$18.4
hp.
9-83
-------
Draft Regulatory Impact Analysis
Table 9A-13: Impact on
Small SI Equipment Market: Class II Tractors UL 250 (Average Price
per Equipment = $l,937)a'b
Small SI Equipment (Class
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
Engineering
Cost/Unit
$0
$1
$1
$12
$11
$11
$11
$11
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
Absolute Change
Change in in Price
Price (%)
$1 0.0%
$1 0.0%
$1 0.0%
$35
$35
$35
$35
$35
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
.8%
.8%
.8%
.8%
.8%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
II Tractors UL
Change in
Quantity
(%)
0.0%
0.0%
0.0%
-1.8%
-1.8%
-1.8%
-1.8%
-1.8%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
-1.3%
250)
Total
Engineering
Costs
(million $)
$0.0
$2.1
$2.1
$22.0
$22.2
$22.1
$22.4
$22.6
$12.6
$12.8
$13.0
$13.2
$13.4
$13.6
$13.8
$14.0
$14.2
$14.4
$14.6
$14.8
$15.0
$15.2
$15.4
$15.6
$15.8
$16.0
$16.2
$16.4
$16.6
$16.8
$17.0
$285.9
$171.3
Change in Equipment
Manufacturers Surplus
(million $)
-$0.4
-$0.5
-$0.5
-$19.7
-$19.9
-$20.2
-$20.5
-$20.7
-$14.8
-$15.1
-$15.3
-$15.5
-$15.8
-$16.0
-$16.3
-$16.5
-$16.7
-$17.0
-$17.2
-$17.5
-$17.7
-$17.9
-$18.2
-$18.4
-$18.7
-$18.9
-$19.1
-$19.4
-$19.6
-$19.9
-$20.1
-$308.5
-$178.8
a Figures are in 2005 dollars.
b Average price per equipment for the market is a weighted average of the price of equipment by hp.
9-84
-------
Economic Impact Analysis
Table 9A-14: Impact on Small SI Equipment Market: Class II Other Lawn and Garden
Equipment UL 250(Average Price per Equipment = $3 12)a'b
Small SI Equipment (Class II Other Lawn and Garden Equipment
UL 250)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Absolute
Engineering Change in
Cost/Unit Price
$0
$1
$1
$12
$11
$11
$11
$11
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$1
$1
$1
$36
$36
$36
$36
$36
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
2005 dollars.
per equipment for the market
Change
in Price
(%)
0.3%
0.3%
0.3%
11.6%
11.6%
11.5%
11.5%
11.5%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
8.0%
is a wei|
Total
Change in Engineering Change in Equipment
Quantity Costs Manufacturers Surplus
(%) (million $) (million $)
-0.2%
-0.2%
-0.2%
-10.5%
-10.4%
-10.4%
-10.3%
-10.3%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
-7.2%
jhted average
$0.0
$0.2
$0.2
$1.7
$1.7
$1.7
$1.7
$1.7
$0.9
$1.0
$1.0
$1.0
$1.0
$1.0
$1.0
$1.
$1.
$1.
$1.
$1.
$1.
$1.
$1.2
$1.2
$1.2
$1.2
$1.2
$1.2
$1.3
$1.3
$1.3
$21.7
$13.1
of the price of equipment by
$0.0
$0.0
$0.0
-$1.3
-$1.3
-$1.3
-$1.4
-$1.4
-$1.0
-$1.0
-$1.0
-$1.0
-$1.1
-$1.1
-$1.1
-$1.1
-$1.1
-$1.1
-$1.2
-$1.2
-$1.2
-$1.2
-$1.2
-$1.2
-$1.3
-$1.3
-$1.3
-$1.3
-$1.3
-$1.3
-$1.4
-$20.6
-$11.9
hp.
9-85
-------
Draft Regulatory Impact Analysis
Table 9A-1 5: Impact
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Small SI
Engineering
Cost/Unit
$0
$1
$1
$12
$11
$11
$11
$11
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
2005 dollars.
per equipment
on Small SI Equipment Market: Class II Gensets/Welders UL 250
(Average Price per Equipment = $666)a'b
Equipment
Absolute
Change in
Price
$1
$1
$1
$34
$34
$34
$34
$34
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
$24
(Class II Gensets/Welders
Change
in Price
(%)
0.1%
0.1%
0.1%
5.2%
5.2%
5.1%
5.1%
5.1%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
3.6%
Change in
Quantity
(%)
-0.1%
-0.1%
-0.1%
-5.7%
-5.7%
-5.6%
-5.6%
-5.6%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
-3.9%
UL 250)
Total
Engineering
Costs
(million $)
$0.0
$0.7
$0.8
$7.8
$7.9
$7.9
$8.0
$8.0
$4.5
$4.5
$4.6
$4.7
$4.8
$4.8
$4.9
$5.0
$5.0
$5.1
$5.2
$5.3
$5.3
$5.4
$5.5
$5.6
$5.6
$5.7
$5.8
$5.8
$5.9
$6.0
$6.1
$101.7
$60.9
Change in Equipment
Manufacturers Surplus
(million $)
-$0.2
-$0.2
-$0.2
-$7.5
-$7.7
-$7.7
-$7.9
-$8.0
-$5.7
-$5.8
-$5.9
-$6.0
-$6.1
-$6.2
-$6.3
-$6.4
-$6.5
-$6.6
-$6.6
-$6.7
-$6.8
-$6.9
-$7.0
-$7.1
-$7.2
-$7.3
-$7.4
-$7.5
-$7.6
-$7.7
-$7.8
-$119.0
-$68.9
for the market is a weighted average of the price of equipment by hp.
9-86
-------
Economic Impact Analysis
Table 9A-16: Impact on Small SI Equipment Market: Class II Pumps/Compressors/ Pressure
Washers UL 250 (Average Price per Equipment = $349)a'b
Small SI Equipment (Class II Pumps/Compressors/Pressure
Washers UL 250)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Engineering
Cost/Unit
$0
$1
$1
$12
$11
$11
$11
$11
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
$6
Absolute
Change in
Price
$1
$1
$1
$35
$35
$35
$35
$35
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
$25
2005 dollars.
per equipment for the market
Change
in Price
(%)
0.2%
0.2%
0.2%
10.2%
10.1%
10.1%
10.0%
10.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
7.0%
is a wei|
Total
Change in Engineering Change in Equipment
Quantity Costs Manufacturers Surplus
(%) (million $) (million $)
-0.2%
-0.2%
-0.2%
-10.2%
-10.1%
-10.1%
-10.0%
-10.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
-7.0%
jhted average
$0.0
$0.3
$0.3
$o o
J.J
$1 1
J.J
$3.3
$3.3
$3.4
$1.9
$1.9
$1.9
$2.0
$2.0
$2.0
$2.1
$2.1
$2.1
$2.1
$2.2
$2.2
$2.2
$2.3
$2.3
$2.3
$2.4
$2.4
$2.4
$2.5
$2.5
$2.5
$2.5
$42.6
$25.5
of the price of equipment by
-$0.1
-$0.1
-$0.1
-$2.8
-$2.9
-$2.9
-$2.9
-$3.0
-$2.2
-$2.2
-$2.2
-$2.3
-$2.3
-$2.3
-$2.4
-$2.4
-$2.4
-$2.5
-$2.5
-$2.5
-$2.6
-$2.6
-$2.6
-$2.7
-$2.7
-$2.7
-$2.8
-$2.8
-$2.8
-$2.9
-$2.9
-$44.8
-$26.0
hp.
9-87
-------
Draft Regulatory Impact Analysis
Table 9A-17:
Impact on
Small
Engineering
Year Cost/Unit
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
$0
$1
$1
$7
$7
$7
$7
$7
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
$5
Small SI Equipment Market: Class II Snowblowers UL 250 (Average
Price per Equipment = $665)a'b
SI Equipment (Class II Snowblowers UL 250)
Absolute
Change in
Price
$1
$1
$1
$5
$5
$5
$5
$5
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
$4
Change
in Price
(%)
0.1%
0.1%
0.1%
0.8%
0.8%
0.8%
0.8%
0.8%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
Change in
Quantity
(%)
-0.1%
-0.1%
-0.1%
-0.8%
-0.8%
-0.8%
-0.8%
-0.8%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
-0.6%
Total
Engineering Change in Equipment
Costs Manufacturers Surplus
(million $) (million $)
$0.0
$0.6
$0.6
$3.7
$3.7
$O *1
3.7
$O *1
3.7
$3.8
$3.0
$3.1
$3.1
$3.2
$o ^
3.2
$o o
3.3
$o o
3.3
$3.4
$3.4
$3.5
$3.5
$3.6
$o s:
3.6
$O *1
3.7
$O *1
3.7
$3.8
$3.8
$3.9
$3.9
$4.0
$4.0
$4.0
$4.1
$62.2
$35.9
-$0.1
-$0.1
-$0.1
-$0.8
-$0.8
-$0.8
-$0.9
-$0.9
-$0.7
-$0.7
-$0.7
-$0.7
-$0.7
-$0.7
-$0.8
-$0.8
-$0.8
-$0.8
-$0.8
-$0.8
-$0.8
-$0.8
-$0.8
-$0.9
-$0.9
-$0.9
-$0.9
-$0.9
-$0.9
-$0.9
-$0.9
-$14.1
-$8.2
a Figures are in 2005 dollars.
b Average price per equipment for the market
is a weighted average of the price of equipment by hp.
9-8
-------
Economic Impact Analysis
Appendix 9B: Impacts on Marine SI Markets
This appendix provides the time series of impacts from 2008 through 2038 for the
following Small SI engines and equipment markets; a complete set of results for all markets can
be found in the docket for this rule (Li, 2007). For engine markets, Results are presented for the
aggregated categories by power. For the vessel markets, results are presented for the categories
with the highest sales.
Marine SI engines: <25 hp; 26-50 hp; 51-100 hp; 101-175 hp; 176-300 hp; >300 hp
SD/I, 175-300 hp and >300 hp
OB recreational, 50-100 hp
OB luxury, 175-300 hp
PWC 100-175 hp
Table 9B-1 through Table 9A-11 provide the time series of impacts for each engine class
market and each selected equipment market, respectively, includes the following:
• average engine or equipment price
• average engineering costs (variable and fixed) per engine or equipment
absolute change in the market price ($)
relative change in market price (%)
relative change in market quantity (%)
total engineering costs associated with each engine or equipment market
• changes in producer surplus associated with each engine or equipment market
All prices and costs are presented in 2005 dollars and real engine or equipment prices are
assumed to be constant during the period of analysis. Net present values were estimated using
social discount rates of 3 percent and 7 percent over the period of analysis.
9-89
-------
Draft Regulatory Impact Analysis
Table 9B-1 : Impact on Marine SI Engine Market:
<25hp (Average Price per Engine = $2,500)a
Marine SI Engine (<25hp)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
Engineering
Cost/Unit
$0
$74
$74
$74
$74
$74
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
$55
Absolute
Change in
Price
$0
$50
$49
$47
$47
$47
$35
$35
$35
$36
$36
$36
$36
$36
$36
$36
$34
$34
$34
$34
$34
$34
$34
$34
$34
$34
$34
$34
$34
$34
$34
Change in
Price
(%)
0.0%
2.0%
1.9%
1.9%
1.9%
1.9%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
1.4%
Change in
Quantity
(%)
0.0%
-3.6%
-3.6%
-3.9%
-3.9%
-3.9%
-3.1%
-3.1%
-3.0%
-2.9%
-2.9%
-2.9%
-2.9%
-2.9%
-2.9%
-2.9%
-3.1%
-3.1%
-3.1%
-3.1%
-3.1%
-3.1%
-3.1%
-3.1%
-3.1%
-3.1%
-3.1%
-3.1%
-3.1%
-3.1%
-3.1%
Total
Engineering
Costs
(million $)
$0.0
$5.4
$5.4
$5.5
$5.5
$5.6
$4.2
$4.2
$4.3
$4.3
$4.3
$4.3
$4.4
$4.4
$4.4
$4.5
$4.5
$4.5
$4.6
$4.6
$4.6
$4.6
$4.7
$4.7
$4.7
$4.8
$4.8
$4.8
$4.8
$4.9
$4.9
$90.1
$55.6
Change in Engine
Manufacturers
Surplus
(million $)
$0.0
-$1.7
-$1.8
-$1.9
-$1.9
-$2.0
-$1.5
-$1.5
-$1.6
-$1.5
-$1.5
-$1.5
-$1.5
-$1.5
-$1.5
-$1.6
-$1.7
-$1.7
-$1.7
-$1.7
-$1.7
-$1.7
-$1.7
-$1.7
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$32.0
-$19.6
Figures are in 2005 dollars.
9-90
-------
Economic Impact Analysis
Table 9B-2: Impact on Marine SI Engine Market:
26-50hp (Average Price per Engine = $5,700)a
Marine SI Engine (26-50hp)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
Engineering
Cost/Unit
$0
$222
$222
$222
$222
$222
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
$173
Absolute
Change in
Price
$0
$187
$185
$185
$183
$183
$142
$142
$142
$142
$143
$143
$143
$143
$143
$143
$143
$143
$143
$143
$143
$143
$143
$143
$143
$143
$143
$143
$143
$143
$143
Change in
Price
(%)
0.0%
3.3%
3.3%
3.3%
3.2%
3.2%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
2.5%
Change in
Quantity
(%)
0.0%
-2.3%
-2.4%
-2.4%
-2.6%
-2.6%
-2.1%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
-2.0%
Total
Engineering
Costs
(million $)
$0.0
$12.1
$12.2
$12.2
$12.3
$12.4
$9.8
$9.8
$9.9
$10.0
$10.0
$10.1
$10.2
$10.2
$10.3
$10.4
$10.4
$10.5
$10.6
$10.6
$10.7
$10.8
$10.9
$10.9
$11.0
$11.1
$11.1
$11.2
$11.3
$11.3
$11.4
$207.2
$127.2
Change in Engine
Manufacturers
Surplus
(million $)
$0.0
-$1.9
-$2.0
-$2.0
-$2.1
-$2.1
-$1.7
-$1.7
-$1.7
-$1.7
-$1.7
-$1.7
-$1.7
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$1.9
-$1.9
-$1.9
-$1.9
-$1.9
-$1.9
-$1.9
-$1.9
-$2.0
-$35.1
-$21.5
Figures are in 2005 dollars.
9-91
-------
Draft Regulatory Impact Analysis
Table 9B-3 : Impact on Marine SI Engine Market:
51-100hp (Average Price per Engine = $9,100)a
Marine SI Engine (51-100hp)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
Engineering
Cost/Unit
$0
$211
$211
$211
$211
$211
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
$162
Absolute
Change in
Price
$0
$182
$180
$180
$178
$178
$136
$136
$136
$136
$137
$137
$137
$137
$137
$137
$137
$137
$137
$137
$137
$137
$137
$137
$137
$137
$137
$137
$137
$137
$137
Change in Change in
Price Quantity
(%) (%)
0.0% 0.0%
2.0%
2.0%
2.0%
1.9%
1.9%
1.5%
1.5%
1.5%
1.5%
1.5%
.5%
.5%
.5%
.5%
.5%
.5%
.5%
.5%
.2%
.3%
.3%
.4%
.4%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.5% -1.1%
.5% -1.1%
.5% -1.1%
.5% -1.1%
1.5% - .1%
1.5% - .1%
1.5% - .1%
1.5% - .1%
1.5% - .1%
1.5% - .1%
1.5% - .1%
1.5% - .1%
Total
Engineering
Costs
(million $)
$0.0
$17.2
$17.3
$17.4
$17.5
$17.7
$13.7
$13.8
$13.9
$14.0
$14.1
$14.2
$14.3
$14.4
$14.5
$14.6
$14.7
$14.8
$14.9
$15.0
$15.1
$15.2
$15.3
$15.4
$15.5
$15.6
$15.7
$15.7
$15.8
$15.9
$16.0
$292.3
$179.7
Change in Engine
Manufacturers
Surplus
(million $)
$0.0
-$2.3
-$2.5
-$2.5
-$2.7
-$2.8
-$2.2
-$2.3
-$2.2
-$2.2
-$2.2
-$2.2
-$2.2
-$2.3
-$2.3
-$2.3
-$2.3
-$2.3
-$2.3
-$2.4
-$2.4
-$2.4
-$2.4
-$2.4
-$2.4
-$2.4
-$2.5
-$2.5
-$2.5
-$2.5
-$2.5
-$46.4
-$29.5
Figures are in 2005 dollars.
9-92
-------
Economic Impact Analysis
Table 9B-4: Impact on Marine SI Engine Market:
101-175hp (Average Price per Engine =$1 l,800)a
Marine SI Engine (101-175hp)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
Engineering
Cost/Unit
$0
$371
$371
$371
$371
$371
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
$284
Absolute
Change in
Price
$0
$319
$315
$315
$312
$312
$237
$237
$238
$238
$238
$238
$238
$238
$238
$238
$238
$238
$238
$238
-------
Draft Regulatory Impact Analysis
Table 9B-5: Impact on Marine SI Engine Market:
176-300hp (Average Price per Engine =$19,000)a
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
Marine SI Engine (176-300hp)
Absolute Change in Change in
Engineering Change in Price Quantity
Cost/Unit Price (%) (%)
$0
$527
$527
$527
$527
$527
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$402
$0 0.0% 0.0%
$456 2.4%
$451 2.4%
$451 2.4%
$445 2.4%
$445 2.4%
$337 1.8%
$338 1.8%
$339 1.8%
$339 1.8%
$339 .8%
$339 .8%
$339 .8%
$339 .8%
$339 .8%
$339 .8%
$339 .8%
$339 .8%
.3%
.4%
.4%
.5%
.5%
.2%
.2%
.2%
.2%
.2%
.2%
.2%
.2%
.2%
.2%
.2%
.2%
$339 .8% -1.2%
$339 .8% -1.2%
$339 .8% -1.2%
$339 .8% -1.2%
$339 .8% -1.2%
$339 1.8% - .2%
$339 1.8% - .2%
$339 1.8% - .2%
$339 1.8% - .2%
$339 1.8% - .2%
$339 1.8% - .2%
$339 1.8% - .2%
$339 1.8% - .2%
Total
Engineering
Costs
(million $)
$0.0
$52.7
$53.0
$53.4
$53.8
$54.2
$41.7
$42.0
$42.3
$42.6
$42.9
$43.2
$43.5
$43.8
$44.1
$44.3
$44.6
$44.9
$45.2
$45.5
$45.8
$46.1
$46.4
$46.7
$47.0
$47.3
$47.6
$47.9
$48.2
$48.5
$48.8
$890.6
$548.1
Change in Engine
Manufacturers
Surplus
(million $)
$0.0
-$7.1
-$7.6
-$7.7
-$8.3
-$8.3
-$6.7
-$6.8
-$6.7
-$6.7
-$6.7
-$6.8
-$6.8
-$6.9
-$6.9
-$6.9
-$7.0
-$7.0
-$7.1
-$7.1
-$7.2
-$7.2
-$7.3
-$7.3
-$7.4
-$7.4
-$7.4
-$7.5
-$7.6
-$7.6
-$7.6
-$137.3
-$83.8
Figures are in 2005 dollars.
9-94
-------
Economic Impact Analysis
Table 9B-6: Impact on Marine SI Engine Market:
300+ hp (Average Price per Engine = $18,000)a
Marine SI Engine (300+ hp)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
Engineering
Cost/Unit
$0
$377
$377
$377
$377
$377
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
$279
Absolute
Change in
Price
$0
$343
$337
$337
$328
$328
$239
$239
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
$241
Change in
Price
(%)
0.0%
1.6%
1.5%
1.5%
1.5%
1.5%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
1.1%
Change in
Quantity
(%)
0.0%
-0.6%
-0.7%
-0.7%
-0.9%
-0.9%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
-0.7%
Total
Engineering
Costs
(million $)
$0.0
$11.9
$12.0
$12.1
$12.2
$12.3
$9.2
$9.3
$9.3
$9.4
$9.5
$9.5
$9.6
$9.7
$9.7
$9.8
$9.9
$9.9
$10.0
$10.1
$10.1
$10.2
$10.3
$10.3
$10.4
$10.4
$10.5
$10.6
$10.6
$10.7
$10.8
$198.0
$122.2
Change in Engine
Manufacturers
Surplus
(million $)
$0.0
-$1.4
-$1.6
-$1.7
-$2.0
-$2.0
-$1.7
-$1.7
-$1.6
-$1.6
-$1.6
-$1.6
-$1.6
-$1.6
-$1.7
-$1.7
-$1.7
-$1.7
-$1.7
-$1.7
-$1.7
-$1.7
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$1.8
-$32.5
-$19.7
Figures are in 2005 dollars.
9-95
-------
Draft Regulatory Impact Analysis
Table 9B-7: Impact on Marine Vessels Market:
SD/I Recreational 175-300 hp (Average Price per Equipment = $32,3
67)a
3.2
$o ^
3.2
$3.3
$3.3
$3.3
$3.3
$3.3
$O A
3.4
$O /\
3.4
$O A
3.4
$O A
3.4
$O A
3.4
$0.0
-$4.9
-$5.5
-$5.5
-$6.3
-$6.3
-$5.1
-$5.2
-$5.1
-$5.1
-$5.1
-$5.1
-$5.1
-$5.2
-$5.2
-$5.2
-$5.3
-$5.3
-$5.3
-$5.4
-$5.4
-$5.5
-$5.5
-$5.5
-$5.6
-$5.6
-$5.6
-$5.7
-$5.7
-$5.7
-$5.8
$56.1 -$102.9
2005 dollars.
per equipment for the market
is a wei|
jhted average
$32.5
of the price of equipment by
-$62.6
hp.
9-96
-------
Economic Impact Analysis
Table 9B-8: Impact on Marine Vessels Market:
SD/I Luxury 300+ hp (Average Price per Equipment = $205,729)a'b
Marine Vessel (SD/I Luxury 300+ hp)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Engineering
Cost/Unit
$0
$11
$142
$142
$312
$312
$312
$311
$285
$285
$271
$271
$271
$271
$271
$271
$271
$271
$271
$271
$271
$271
$271
$271
$271
$271
$271
$271
$271
$271
$271
Absolute
Change in
Price
$0
$292
$358
$358
$443
$443
$369
$369
$356
$356
$349
$349
$349
$349
$349
$349
$349
$349
$349
$349
$349
$349
$349
$349
$349
$349
$349
$349
$349
$349
$349
2005 dollars.
per equipment for the market
Change
in Price
(%)
0.0%
0.1%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
0.2%
is a wei|
Total
Change in Engineering Change in Equipment
Quantity Costs Manufacturers Surplus
(%) (million $) (million $)
0.0%
-0.3%
-0.3%
-0.3%
-0.4%
-0.4%
-0.4%
-0.4%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
-0.3%
jhted average
$0.0
$0.1
$1.3
$1.3
$2.8
$2.8
$2.8
$2.9
$2.6
$2.7
$2.5
$2.6
$2.6
$2.6
$2.6
$2.6
$2.6
$2.7
$2.7
$2.7
$2.7
$2.7
$2.8
$2.8
$2.8
$2.8
$2.8
$2.8
$2.9
$2.9
$2.9
$46.7
$27.0
of the price of equipment by
$0.0
-$2.2
-$2.8
-$2.8
-$3.5
-$3.5
-$2.9
-$2.9
-$2.9
-$2.9
-$2.8
-$2.9
-$2.9
-$2.9
-$2.9
-$2.9
-$3.0
-$3.0
-$3.0
$O f\
3.0
$o r\
3.0
-$3.1
-$3.1
-$3.1
-$3.1
-$3.1
$o ^
3.2
$o *•>
3.2
$o ^
3.2
-$3.2
-$3.2
-$56.7
-$34.2
hp.
9-97
-------
Draft Regulatory Impact Analysis
Table 9B-9: Impact on Marine Vessels Market:
OB Recreational 50-100 hp (Average Price per Equipment = $21,569)a'b
Marine Vessel (OB Recreational 50-100 hp)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Engineering
Cost/Unit
$0
$7
$27
$27
$48
$48
$48
$48
$44
$44
$39
$39
$39
$39
$39
$39
$39
$39
$39
$39
$39
$39
$39
$39
$39
$39
$39
$39
$39
$39
$39
Absolute
Change in
Price
$0
$130
$139
$139
$149
$149
$120
$119
$118
$118
$115
$115
$115
$115
$115
$115
$115
$115
$115
$115
$115
$115
$115
$115
$115
$115
$115
$115
$115
$115
$115
2005 dollars.
per equipment for the market
Total
Change Change in Engineering Change in Equipment
in Price Quantity Costs Manufacturers Surplus
(%) (%) (millions) (million $)
0.0% 0.0%
0.6%
0.6%
0.6%
0.7%
0.7%
0.6%
0.6%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
.2%
.3%
.3%
.4%
.4%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
.1%
is a weighted average
$0.0
$0.4
$1.7
$1.7
$3.1
$3.1
$3.2
$3.1
$2.9
$2.9
$2.6
$2.6
$2.6
$2.6
$2.7
$2.7
$2.7
$2.7
$2.7
$2.8
$2.8
$2.8
$2.8
$2.8
$2.8
$2.9
$2.9
$2.9
$2.9
$2.9
$2.9
$49.7
$29.2
of the price of equipment by
$0.0
-$0.2
-$0.8
-$0.8
-$1.4
-$1.5
-$1.5
-$1.5
-$1.3
-$1.4
-$1.2
-$1.2
-$1.2
-$1.2
-$1.2
-$1.2
-$1.3
-$1.3
-$1.3
-$1.3
-$1.3
-$1.3
-$1.3
-$1.3
-$1.3
-$1.3
-$1.3
-$1.3
-$1.4
-$1.4
-$1.4
-$23.2
-$13.6
hp.
9-98
-------
Economic Impact Analysis
Table 9B-10: Impact on Marine Vessels Market:
OB Luxury 175-300 hp (Average Price per Equipment = $104,598)a'b
Marine Vessel
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Engineering
Cost/Unit
$0
$19
$116
$116
$215
$215
$215
$214
$195
$195
$182
$182
$182
$182
$182
$182
$182
$182
$182
$182
$182
$182
$182
$182
$182
$182
$182
$182
$182
$182
$182
Absolute
Change in
Price
$0
$763
$804
$804
$845
$845
$672
$672
$663
$663
$658
$658
$658
$658
$658
$658
$658
$658
$658
$658
$658
$658
$658
$658
$658
$658
$658
$658
$658
$658
$658
2005 dollars.
per equipment for the market
(OB Luxury 175-300 hp)
Total
Change Change in Engineering Change in Equipment
in Price Quantity Costs Manufacturers Surplus
(%) (%) (millions) (million $)
0.0% 0.0%
0.7%
0.8%
0.8%
0.8%
0.8%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
.5%
.5%
.5%
.6%
.6%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
.3%
is a weighted average
$0.0
$0.1
$0.4
$0.4
$0.8
$0.8
$0.8
$0.8
$0.8
$0.8
$0.7
$0.7
$0.7
$0.7
$0.7
$0.7
$0.8
$0.8
$0.8
$0.8
$0.8
$0.8
$0.8
$0.8
$0.8
$0.8
$0.8
$0.8
$0.8
$0.8
$0.8
$13.4
$7.8
of the price of equipment by
$0.0
-$2.5
-$2.6
-$2.6
-$2.8
-$2.8
-$2.2
-$2.3
-$2.2
-$2.3
-$2.3
-$2.3
-$2.3
-$2.3
-$2.3
-$2.3
-$2.4
-$2.4
-$2.4
-$2.4
-$2.4
-$2.4
-$2.4
-$2.5
-$2.5
-$2.5
-$2.5
-$2.5
-$2.5
-$2.6
-$2.6
-$46.4
-$28.4
hp.
9-99
-------
Draft Regulatory Impact Analysis
Table 9B-1 1 : Impact on Marine Vessels Market:
PWC 100-175 hp (Average Price per Equipment = $9,986)a'b
Marine Vessel (PWC 100-175 hp)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
NPV (3%)
NPV (7%)
a Figures are in
b Average price
Absolute
Engineering Change in
Cost/Unit Price
$0
$98
$98
$98
$98
$98
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$68
$0
$63
$63
$73
$73
$73
$54
$54
$54
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
$50
2005 dollars.
per equipment for the market
Total
Change Change in Engineering Change in Equipment
in Price Quantity Costs Manufacturers Surplus
(%) (%) (millions) (million $)
0.0% 0.0%
0.6%
0.6%
0.7%
0.7%
0.7%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
.3%
.3%
.5%
.5%
.5%
.1%
.1%
.1%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
.0%
is a weighted average
$0.0
$5.8
$5.8
$5.9
$5.9
$6.0
$4.2
$4.2
$4.2
$4.2
$4.3
$4.3
$4.3
$4.4
$4.4
$4.4
$4.4
$4.5
$4.5
$4.5
$4.6
$4.6
$4.6
$4.7
$4.7
$4.7
$4.7
$4.8
$4.8
$4.8
$4.9
$91.2
$56.8
of the price of equipment by
$0.0
-$2.2
-$2.2
-$2.6
-$2.6
-$2.6
-$1.9
-$1.9
-$2.0
-$1.8
-$1.8
-$1.9
-$1.9
-$1.9
-$1.9
-$1.9
-$1.9
-$1.9
-$1.9
-$2.0
-$2.0
-$2.0
-$2.0
-$2.0
-$2.0
-$2.0
-$2.0
-$2.1
-$2.1
-$2.1
-$2.1
-$39.2
-$24.3
hp.
9-100
-------
Economic Impact Analysis
Appendix 9C: Time Series Projections of Social Cost
This appendix provides a time series of the rule's projected social costs for each year
through 2038. Costs are presented in 2005 dollars. In addition, this appendix includes the net
present values by stakeholder using social discount rates of 3 percent and 7 percent over the
period of analysis. As a result, it illustrates how the choice of discount rate determines the
present value of the total social costs of the program.
9-101
-------
Table 9C: Time Series Projection of Social Costs: 2008 to 2038 (Million $)a
Consumer Surplus Change, Total
Marine SI
End users (households)
Small SI
End users (households)
Producer Surplus Change, Total
Marine SI
Engine manufacturers
Equipment manufacturers
Small SI
Engine manufacturers
Equipment manufacturers
Fuel Savings
Consumer savings
Fuel
Tax
Government revenue
Total Surplus Change
2008
-$7.5
$0.0
-$7.5
-$2.0
$0.0
$0.0
$0.0
-$2.0
-$0.4
-$1.7
$3.1
$3.8
$3.1
$0.7
-$0.7
-$6.4
2009
-$118.2
-$110.6
-$7.6
-$50.6
-$48.5
-$18.1
-$30.4
-$2.1
-$0.4
-$1.7
$13.7
$16.7
$13.7
$3.0
-$3.0
-$155.1
2010
-$128.5
-$116.1
-$12.4
-$59.5
-$54.8
-$19.5
-$35.3
-$4.7
-$0.4
-$4.3
$25.4
$30.9
$25.4
$5.5
-$5.5
-$162.6
2011
-$331.6
-$117.8
-$213.7
-$131.8
-$56.0
-$19.8
-$36.2
-$75.8
-$10.9
-$64.8
$64.9
$78.8
$64.9
$13.9
-$13.9
-$398.5
2012
-$477.2
-$124.2
-$353.0
-$160.9
-$63.3
-$21.4
-$41.9
-$97.6
-$18.2
-$79.4
$103.5
$125.7
$103.5
$22.2
-$22.2
-$534.7
2013
-$481.1
-$125.1
-$356.0
-$162.3
-$63.8
-$21.5
-$42.2
-$98.5
-$18.4
-$80.2
$136.5
$165.9
$136.5
$29.3
-$29.3
-$506.9
2014
-$460.7
-$99.6
-$361.0
-$152.5
-$52.6
-$17.4
-$35.2
-$99.9
-$18.6
-$81.3
$161.2
$195.9
$161.2
$34.7
-$34.7
-$451.9
2015
-$465.4
-$100.3
-$365.1
-$153.6
-$52.9
-$17.5
-$35.4
-$100.8
-$18.9
-$81.9
$182.3
$221.5
$182.3
$39.2
-$39.2
-$436.7
2016
-$389.4
-$100.0
-$289.5
-$125.7
-$52.0
-$17.3
-$34.7
-$73.7
-$15.0
-$58.8
$200.9
$244.1
$200.9
$43.2
-$43.2
-$314.2
2017
-$365.1
-$100.3
-$264.8
-$122.4
-$52.0
-$17.4
-$34.6
-$70.4
-$13.7
-$56.8
$216.2
$262.6
$216.2
$46.5
-$46.5
-$271.3
2018
-$369.1
-$100.2
-$269.0
-$122.9
-$51.3
-$17.3
-$34.0
-$71.5
-$13.9
-$57.7
$229.9
$279.3
$229.9
$49.4
-$49.4
-$262.1
(continued)
-------
Table 9C: Time Series Projection of Social Costs (Million $) (continued)
Consumer Surplus Change, Total
Marine SI
End users (households)
Small SI
End users (households)
Producer Surplus Change, Total
Marine SI
Engine manufacturers
Equipment manufacturers
Small SI
Engine manufacturers
Equipment manufacturers
Fuel Savings
Consumer savings
Fuel
Tax
Government revenue
Total Surplus Change
2019
-$374.1
-$100.9
-$273.2
-$124.3
-$51.7
-$17.4
-$34.3
-$72.7
-$14.1
-$58.6
$242.1
$294.2
$242.1
$52.0
-$52.0
-$256.2
2020
-$378.9
-$101.6
-$277.4
-$125.8
-$52.0
-$17.5
-$34.5
-$73.8
-$14.3
-$59.5
$253.1
$307.5
$253.1
$54.4
-$54.4
-$251.6
2021
-$383.8
-$102.3
-$281.5
-$127.3
-$52.4
-$17.6
-$34.7
-$74.9
-$14.5
-$60.4
$263.3
$319.9
$263.3
$56.6
-$56.6
-$247.7
2022
-$388.6
-$102.9
-$285.7
-$128.7
-$52.7
-$17.8
-$35.0
-$76.0
-$14.8
-$61.2
$272.9
$331.6
$272.9
$58.7
-$58.7
-$244.4
2023
-$393.5
-$103.6
-$289.9
-$130.2
-$53.1
-$17.9
-$35.2
-$77.1
-$15.0
-$62.1
$281.4
$341.9
$281.4
$60.5
-$60.5
-$242.2
2024
-$398.4
-$104.4
-$294.1
-$131.9
-$53.7
-$18.1
-$35.6
-$78.2
-$15.2
-$63.0
$289.3
$351.5
$289.3
$62.2
-$62.2
-$241.0
2025
-$403.3
-$105.1
-$298.3
-$133.3
-$54.0
-$18.2
-$35.8
-$79.3
-$15.4
-$63.9
$296.6
$360.4
$296.6
$63.8
-$63.8
-$240.0
2026
-$408.2
-$105.8
-$302.5
-$134.8
-$54.4
-$18.3
-$36.0
-$80.5
-$15.6
-$64.8
$303.6
$368.8
$303.6
$65.2
-$65.2
-$239.5
2027
-$413.1
-$106.5
-$306.7
-$136.3
-$54.7
-$18.5
-$36.3
-$81.6
-$15.8
-$65.7
$310.1
$376.7
$310.1
$66.6
-$66.6
-$239.3
2028
-$418.0
-$107.1
-$310.9
-$137.8
-$55.1
-$18.6
-$36.5
-$82.7
-$16.1
-$66.7
$316.3
$384.2
$316.3
$68.0
-$68.0
-$239.5
2029
-$422.9
-$107.8
-$315.1
-$139.3
-$55.4
-$18.7
-$36.7
-$83.8
-$16.3
-$67.6
$321.9
$391.1
$321.9
$69.2
-$69.2
-$240.2
(continued)
-------
Table 9C: Time Series Projection of Social Costs (million $) (continued)
Consumer Surplus Change, Total
Marine SI
End users (households)
Small SI
End users (households)
Producer Surplus Change, Total
Marine SI
Engine manufacturers
Equipment manufacturers
Small SI
Engine manufacturers
Equipment manufacturers
Fuel Savings
Consumer savings
Fuel
Tax
Government revenue
Total Surplus Change
2030
-$427.8
-$108.5
-$319.3
-$140.7
-$55.8
-$18.8
-$37.0
-$84.9
-$16.5
-$68.5
$327.3
$397.6
$327.3
$70.3
-$70.3
-$241.3
2031
-$432.7
-$109.2
-$323.5
-$142.2
-$56.1
-$18.9
-$37.2
-$86.1
-$16.7
-$69.4
$332.3
$403.7
$332.3
$71.4
-$71.4
-$242.6
2032
-$437.6
-$109.9
-$327.7
-$143.7
-$56.5
-$19.1
-$37.4
-$87.2
-$16.9
-$70.3
$337.1
$409.5
$337.1
$72.4
-$72.4
-$244.2
2033
-$442.6
-$110.6
-$332.0
-$145.2
-$56.9
-$19.2
-$37.7
-$88.3
-$17.1
-$71.2
$341.7
$415.1
$341.7
$73.4
-$73.4
-$246.0
2034
-$447.5
-$111.3
-$336.2
-$146.6
-$57.2
-$19.3
-$37.9
-$89.4
-$17.4
-$72.1
$346.1
$420.5
$346.1
$74.4
-$74.4
-$248.0
2035
-$452.4
-$112.0
-$340.4
-$148.1
-$57.6
-$19.4
-$38.2
-$90.6
-$17.6
-$73.0
$350.4
$425.7
$350.4
$75.3
-$75.3
-$250.1
2036
-$457.3
-$112.7
-$344.6
-$149.6
-$57.9
-$19.5
-$38.4
-$91.7
-$17.8
-$73.9
$354.5
$430.7
$354.5
$76.2
-$76.2
-$252.3
2037
-$462.2
-$113.4
-$348.8
-$151.1
-$58.3
-$19.7
-$38.6
-$92.8
-$18.0
-$74.8
$358.5
$435.6
$358.5
$77.1
-$77.1
-$254.7
2038
-$467.1
-$114.1
-$353.0
-$152.5
-$58.6
-$19.8
-$38.9
-$93.9
-$18.2
-$75.7
$362.5
$440.4
$362.5
$77.9
-$77.9
-$257.1
NPV
(3%)
-$7,392.2
-$2,058.8
-$5,333.4
-$2,490.0
-$1,043.2
-$354.4
-$688.8
-$1,446.9
-$275.0
-$1,171.8
$4,356.1
$5,292.3
$4,356.1
$936.2
-$936.2
-$5,526.1
NPV (7%)
-$4,322.0
-$1,259.9
-$3,062.1
-$1,472.0
-$633.9
-$216.2
-$417.6
-$838.2
-$157.8
-$680.4
$2,291.5
$2,784.0
$2,291.5
$492.5
-$492.5
-$3,502.6
Figures are in 2005 dollars.
-------
Economic Impact Analysis
Appendix 9D: Overview of Model Equations and Calculation
To develop the economic impact model, we use set of nonlinear supply and demand
equations for the affected markets and transform them into a set of linear supply and demand
equations. These resulting equations describe stakeholder production and consumption
responses to policy-induced cost and price changes in each market. They also are used to
specify the conditions for a new with-policy equilibrium. We describe these equations in more
detail below.
9D.1 Economic Model Equations
Supply Equations
First, we consider the formal definition of the elasticity of supply with respect to changes
in own price:
(9D1)
1 1 /
dpi p
Next, we can use "hat" notation to transform Eq. (C. 1) to proportional changes and rearrange
terms:
Q, = esp (9D.la)
where
Qs = percentage change in the quantity of market supply,
es = market elasticity of supply, and
p = percentage change in market price.
As Fullerton and Metcalfe (2002) note, this approach takes the elasticity definition and turns it
into a linear behavioral equation for each market.
To introduce the direct impact of the regulatory program, we assume the direct per-unit
compliance cost (c) leads to a proportional shift in the marginal cost of production. Under the
assumption of perfect competition (price equals marginal cost), we can approximate this shift at
the initial equilibrium point as follows:
MC = -- = — • (9D.2)
p0
The with-regulation supply response to price and cost changes can now be written as:
9-105
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Draft Regulatory Impact Analysis
(9D.3)
For equipment producers, the supply response should also simultaneously accounts for changes
in equilibrium input prices (engines). To do this, we modify Eq. (9D.2) as follows:
M _
MC0 Po (9D.3a)
where Apengine is the equilibrium change in the engine price and a is the ratio of engines used per
unit of equipment. For example, if one piece of equipment uses only one engine, then a = 1 .
This equation can accommodate other engine to equipment ratios by multiplying Apeng by the
appropriate engine-to-equipment ratio (a).
Demand Equations
Similar to supply, we can characterize equipment demand responses to price changes as:
4 = r\dp (9D.4)
where
Qd = percentage change in the quantity of market demand,
r|d = market elasticity of demand, and
p = percentage change in market price.
In contrast to equipment demand, the demand for engines is a derived demand and is related to
equipment supply decisions. In order to maintain a constant engine-to-equipment ratio, the
demand for engines is specified as:
yv /*.
Qdengines = Qsequipment (9D.5)
Market Equilibrium Conditions
In response to the exogenous increase in equipment and engine production costs,
stakeholder responses are completely characterized by represented in Eq. (9D.3)(equipment and
engine supply), Eq. (9D.4) (equipment demand), and Eq. (9D.5)(engine demand). Next, we
specify the relationship that must hold for markets to "clear", that is, supply in each market
equals demand. Given the equations specified above, the new equilibrium satisfies the condition
that for each market, the proportional change in supply equals the proportional change in
demand:
& = Q, (9D-6)
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Economic Impact Analysis
9D.2 Computing With-Regulation Equilibrium Conditions
The choice of efficient model solution algorithms depends on several factors such as the
number of markets included in the economic model, complexity of interactions between
consumers and producers within these markets, and the software used to construct the model. To
find the new market equilibrium prices and quantities, we used a solution algorithm that has
proven very useful in "searching" for the equilibrium prices and quantities for partial equilibrium
spreadsheet simulations with complicated relationships. We describe this approach in more detail
below.
9D.2.1 Conceptual Description of RTFs Spreadsheet Model Solution Algorithm:
PE_Walrasian_Auctioneer©2005
The French economist Leon Walras proposed one early model of market price adjustment
by using the following thought experiment. Suppose there is a hypothetical agent that facilitates
market adjustment by playing the role of an "auctioneer." He announces prices, collects
information about supply and demand responses (without transactions actually taking place), and
continues this process until market equilibrium is achieved.
For example, consider the with-regulation supply and demand conditions at the without-
regulation equilibrium price (P) (see Figure 9D-la). The auctioneer determines that the quantity
demanded (A) exceeds the quantity supplied (B) at this price and calls out a new (higher) price
(P') based on the amount of excess demand. Consumers and producers make new consumption
and production choices at this new price (i.e., they move along their respective demand and
supply functions), and the auctioneer checks again to see if excess demand or supply exists. This
process continues until P = P* (point C in Figure 9D-la) is reached (i.e., excess demand is zero
in the market). A similar analysis takes place when excess supply exists. The auctioneer calls out
lower prices when the price is higher than the equilibrium price.
Figure 9D-la. Computing with Regulation Equilibrium
$/Q
Price
Increase
S,: With Regulation
Q/t
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Draft Regulatory Impact Analysis
The model uses a similar type of algorithm for determining with-regulation equilibria,
and the process can be summarized by six recursive steps:
1. Impose the control costs on affected supply segments, thereby affecting their supply
decisions.
2. Recalculate the market supply in each market. Excess demand currently exists.
3. Determine the new prices via a price revision rule. We used a rule similar to the
factor price revision rule described by Kimbell and Harrison (1986). P; is the market
price at iteration i, qd is the quantity demanded, and qs is the quantity supplied. The
parameter z influences the magnitude of the price revision and the speed of
convergence. The revision rule increases the price when excess demand exists,
lowers the price when excess supply exists, and leaves the price unchanged when
market demand equals market supply. The price adjustment is expressed as follows:
(9D.7)
4. Recalculate market supply with new prices.
5. Compute market demand in each market.
6. Compare supply and demand in each market. If equilibrium conditions are not
satisfied, go to Step 3, resulting in a new set of market prices. Repeat until
equilibrium conditions are satisfied (i.e., the ratio of supply and demand is arbitrarily
close to one). When the ratio is appropriately close to one, the market-clearing
condition of supply equals demand is satisfied.
9D.2.2 Consumer and Producer Welfare Calculations
The change in consumer surplus in the affected markets can be estimated using the
following linear approximation method:
ACS = -Q1«Ap + 0.5«AQ«Ap. (9D.8)
As shown, higher market prices and reduced consumption lead to welfare losses for consumers.
A geometric representation of this calculation is illustrated in Figure 9D-lb.
For affected supply, the change in producer surplus can be estimated with the following
equation:
APS = Ch • (Ap - c) - 0.5 • AQ • (Ap - c). (9D.9)
Increased regulatory costs and output declines have a negative effect on producer surplus,
because the net price change (Ap - c) is negative. However, these losses are mitigated, to some
degree, as a result of higher market prices. A geometric representation of this calculation is
illustrated in Figure 9D-lb.
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Economic Impact Analysis
A consumer surplus
A producer surplus
A total surplus
=-[fghd + dhc]
=[fghd - aehb] - bdc
=-[aehb + dhc + bdc]
Figure 9D-lb. Welfare Calculations
Price
Increase
: With Regulation
Unit Cost Increase
S0: Without Regulation
Output
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Draft Regulatory Impact Analysis
Appendix 9E: Elasticity Parameters for Economic Impact Modeling
The Economic Impact Model (EIM) relies on elasticity parameters to estimate the
behavioral response of consumers and producers to the regulation and its associated social costs.
To operationalize the market model, supply and demand elasticities are needed to represent the
behavioral adjustments that are likely to be made by market participants. The following
parameters are needed:
supply and demand elasticities for Marine SI equipment markets
supply and demand elasticities for Small SI equipment markets
supply elasticities for Marine SI engine markets
• supply elasticities for Small SI engine markets
Note that demand elasticities for the Marine SI and Small SI engine markets are not
estimated because they are derived internally in the model. They are a function of changes in
output levels in the equipment markets.
Tables 9E-1 and 9E-2 contain the demand and supply elasticities used to estimate the
economic impact of the rule. Two methods were used to obtain the supply and demand
elasticities used in the EIM. First, the professional literature was surveyed to identify elasticity
estimates used in published studies. Second, when literature estimates were not available for
specific markets, established econometric techniques were used to estimate supply and demand
elasticity parameters directly. Since very few studies have been identified to quantify elasticities
for Small SI and Marine SI markets in the literature survey, the supply and demand elasticities
for all of the equipment and engine markets were estimated econometrically.
This appendix describes the methods used to estimate demand and supply elasticities for
Marine SI and Small SI engines and equipment markets and presents the data sources and the
regression results obtained from applying those methods.
Finally, it should be noted that these elasticities reflect intermediate run behavioral
changes. In the long run, supply and demand are expected to be more elastic since more
substitutes may become available.
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Economic Impact Analysis
Table 9E-1: Summary of Market Supply Elasticities Used in the Market Model
Markets
Estimate
Source
Method
Input Data Summary
Recreational
Marine
All vessel types 2.3
except PWC
PWC 3.4
Small SI
All lawn and 3.4
garden
equipment
Generators 3.3
All Engines
Categories
EPA econometric
estimate
Table 9E-4
EPA econometric
estimate
Table 9E-5
EPA econometric
estimate
Table 9E-6
EPA econometric
estimate
Table 9E-7
EPA econometric
estimate
Table 9E-3
Cobb-Douglas production
function
Cobb-Douglas production
function
Cobb-Douglas production
function
Cobb-Douglas production
function
Cobb-Douglas production
function
Bartlesman et al.
(2000); 1958-1996;
SIC 3732
Bartlesman et al.
(2000); 1958-1996;
SIC 3799
Bartlesman et al.
(2000); 1958-1996;
SIC 3524
Bartlesman et al.
(2000); 1966-1996;
SIC 3621
Bartlesman et al.
(2000); 1958-1996;
SIC 3519
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Draft Regulatory Impact Analysis
Table 9E-2: Summary of Market Demand Elasticities Used in the Market Model
Primary Input Data
Market
Equipment
All recreational
marine (including
PWC)
Lawnmowers
Estimate
-2.0
-0.2
Source Method
EPA econometric Simultaneous
estimate equation (3 SLS)
Table 9E-8
EPA econometric estimate Simultaneous
Summary
Bartlesman et al. (2000);
1958-1996; SIC 3732
AIR/NERA (2003);
Lawn and garden -1.0
tractors
Pumps/compressors/ -1.0"
pressure washers,
snowblowers
Agriculture, -1.0a
construction,
general industrial
Other lawn and -0.9b
garden
Table 9E-9, equation (3SLS)
Column 2
EPA econometric estimate Simultaneous
Table 9E-9, equation (2SLS)
Column 5
EPA econometric estimate Simultaneous
Table 9E-9, equation (2SLS)
Column 5
EPA econometric estimate Simultaneous
Table 9E-9, equation (2SLS)
Column 5
EPA econometric estimate Simultaneous
Table 9E-9, equation (2SLS)
Column 3
1973-2002
U.S. Census Bureau, Current
Industrial Reports, MA333A
2000 and selected previous
years; 1980-1997
U.S. Census Bureau, Current
Industrial Reports, MA333A
2000 and selected previous
years; 1980-1997
U.S. Census Bureau, Current
Industrial Reports, MA333A
2000 and selected previous
years; 1980-1997
U.S. Census Bureau, Current
Industrial Reports, MA333A
2000 and selected previous
years; 1980-1997
All handheld lawn
and garden
equipment
-1.9 EPA econometric estimate Simultaneous
Table 9E-9, equation (2SLS)
Column 4
U.S. Census Bureau, Current
Industrial Reports, MA333A
2000 and selected years;
1980-1997
Gensets/welders
Class 1
-1.4 EPA econometric
estimate
Table 9E-10,
Column 2
Simultaneous
equation (3 SLS)
U.S. Census Bureau, Current
Industrial Reports, MA335H
2000 and selected years;
1980-1997
Gensets/welders
Class 2
All Engines
-1.1 EPA econometric
estimate
Table 9E-10,
Column 3
Derived demand
Simultaneous
equation (3 SLS)
NA
U.S. Census Bureau, Current
Industrial Reports, MA335H
2000 and selected years;
1980-1997
a Uses econometric estimate for lawn and garden tractors.
b Uses econometric estimate for commercial mowers.
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Economic Impact Analysis
9E.1 Supply Elasticities
We use a two-steps approach to estimate the price elasticity of supply. In the first step,
we estimate an industry production function by using the regression model. In the second step,
we calculate the supply elasticity by the parameters estimated in the estimated production
function. This section discusses the regression model used to estimate the industry production
function, data sources used for the regression, and estimated results for supply elasticities. The
economics theory on the relationship between the supply elasticity and the production function is
discussed in Appendix 9F.
In economics, the production function is defined as the relationship between inputs and
outputs of the production process. In this case, we assume that Small SI and Marine SI industry
follows the Cobb-Douglas production function, and is specified as
Qt = A (K/K (L,)^ (M/" tA (9E. 1)
where
Qt = output in year t,
Kt = real capital consumed in production in year t,
Lt = quantity of labor used in year t,
Mt = material inputs in year t, and
t = a time trend variable to reflect technology changes.
This equation can be written in linear form by taking the natural logarithms of each side of the
equation. The parameters of this model, aK, aL, aM, can then be estimated using linear regression
techniques:
In Qt = In A + aK In Kt + aL In Lt + aM In Mt + A In t (E9.2)
Under the assumptions of a competitive market and perfect competition, the elasticity of supply
with respect to the price of the final product can be expressed in terms of the parameters of the
production function:14
Supply Elasticity = (aL + aM) / (1 - aL - aM). (9E.3)
To maintain the desired properties of the Cobb-Douglas production function, the analyst
must place restrictions on the estimated coefficients. For example, if aL + aM = 1, then the supply
elasticity will be undefined. Alternatively, if aL + aM > 1, this yields a negative supply elasticity.
Thus, a common assumption is that aK + aL + aM = 1. This implies constant returns to scale,
which is consistent with most empirical studies.
14 Appendix 9F provides the derivation of this result.
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Draft Regulatory Impact Analysis
9E.1.1 Data Sets
The National Bureau of Economic Research-Center for Economic Studies (Bartlesman,
Becker, and Gray, 2000) publishes industry-level data used for the analysis. In cases where a
price index was not available, we used the most recent implicit gross domestic product (GDP)
price deflator reported by the U.S. Bureau of Economic Analysis (BEA, 2004).15 The following
variables were used:
• value of shipments (NBER-CES),
• price index of value shipments (NBER-CES),
• production worker wages (NBER-CES),
• GDP deflator (BEA)
• cost of materials (NBER-CES),
• price index for materials (NBER-CES), and
• value added (NBER-CES).
To provide a measure of capital consumed, a capital variable was calculated as follows:
Capital = (Value added - Production worker wages)/GDP deflator
9E.1.2 Results of Supply Elasticity Estimation
We used an autoregressive error model to estimate Eq. (9E.2). SAS procedure PROC
AUTOREG computes a linear regression corrected for serial correlation. We assume the error
term is AR(2). This approach is identical to the one used successfully for the Nonroad CI
Engines and Equipment EIA completed in 2003 (EPA, 2004), with some of the data series
updated with the most recent data. Using this model, reasonable estimates were obtained for
Small SI products. Durbin-Watson statistics were calculated to check for autocorrelation and
Goldfeld-Quandt tests to check for heteroskedasticity. As shown in Tables 9E-3 through 9E-7,
supply elasticity estimates for Small SI products range from 2.3 (Boat Building) to 3.8
(Engines).
15 All values are expressed in $1987. Note the GDP deflators have been updated since RTFs estimation of
supply elasticities for the nonroad rule. As a result, the elasticity estimation method is the same; however, the
coefficient estimates may vary slightly.
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Economic Impact Analysis
Table 9E-3: Gasoline Engines: SIC
Classified: 1958 to 1996
Number of Observations = 39
Total R-square = 0.9978
Durbin-Watson = 1.80 (1% critical
Goldfeld-Quandt F = 3.10 (p-value
Supply Elasticity = 3.8
Variable
intercept
InK
InL
InM
Int
3519 Internal Combustion Engines, Not Elsewhere
values = 1.085, 1.517)
= 0.018); DF=14
Estimated Coefficients
0.962
0.207
0.207
0.587
0.022
Table 9E-4: Gasoline-Powered Boats: SIC 3732 Boat Building
Number of Observations = 39
Total R-square = 0.9976
Durbin-Watson = 1.89 (1% critical
Goldfeld-Quandt F = 1.76 (p-value
Supply Elasticity = 2.3
Variable
intercept
InK
InL
InM
Int
values = 1.085, 1.517)
= 0.141);DF=14
Estimated Coefficients
1.144
0.303
0.328
0.369
0.022
t-statistic
24.21
4.73
5.60
13.04
2.37
and Repairing:
t-statistic
25.42
5.73
7.28
7.34
1.56
p value
O.OOOl
O.OOOl
O.OOOl
O.OOOl
0.0238
1958 to 1996
p-value
O.OOOl
O.OOOl
O.OOOl
O.OOOl
0.1295
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Draft Regulatory Impact Analysis
Table 9E-5: PWCs, ATVs, Snowmobiles: SIC 3799 Transportation Equipment, Not Elsewhere
Classified: 1958 to 1996
Number of Observations = 39
Total R-square = 0.9978
Durbin-Watson = 1.758 (1% critical values =
Goldfeld-Quandt F = 2.99 (p-value = 0.025)
Supply Elasticity = 3.4
= 1.085, 1.517)
; DF=14
Variable Estimated Coefficients
intercept
InK
InL
InM
Int
Table 9E-6: Small Handheld/Nonhandheld:
Lawn and Garden Equipment: 1958 to 1996
Number of Observations = 39
Total R-square = 0.9964
Durbin-Watson = 1.71 (1% critical values =
Goldfeld-Quandt F = 2.08 (p-value = 0.084)
Supply Elasticity = 3.4
0.786
0.229
0.127
0.644
0.028
SIC 3 524 Lawn and
1.085, 1.517)
; DF=14
Variable Estimated Coefficients
intercept
InK
InL
InM
Int
0.662
0.225
0.068
0.707
0.042
t-statistic
19.4
10.4
4.57
20.2
2.90
Garden Tractors
t-statistic
13.03
3.69
1.79
11.09
2.77
p value
O.OOOl
O.OOOl
O.OOOl
O.OOOl
0.0065
and Home
p value
O.OOOl
0.0008
0.0822
O.OOOl
0.0091
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Economic Impact Analysis
Table 9E-7: Gensets and Marine Generators: SIC 3621 Motors and Generators: 1966 to 1996
Number of Observations = 31
Total R-square = 0.9930
Durbin-Watson = 1.749 (1% critical values = 0.960,1.510 )
Goldfeld-Quandt F = 0.89 (p-value = 0.576); DF=11
Supply Elasticity = 3.3
Variable
intercept
InK
InL
InM
Int
Estimated Coefficients
1.0119
0.2346
0.1574
0.6081
-0.0127
t-statistic
19.6
4.62
3.15
11.64
-0.51
p value
O.0001
O.0001
0.0042
O.OOOl
0.6176
9E.2 Demand Elasticities
To obtain demand elasticity parameters, we estimated a simultaneous system of demand
and supply equations using instrumental variables methodology by either two-stage least squares
(2SLS) or three-stage least squares (3SLS) regression. This type of partial equilibrium market
supply/demand model is specified as a system of interdependent equations in which the price and
output of a product are simultaneously determined by the interaction of producers and consumers
in the market. In simultaneous equation models, where variables in one equation feed back into
variables in another equation, the error terms are correlated with the endogenous variables (price
and output). Use of a single-equation ordinary least squares (OLS) estimation of individual
equations will lead to biased and inconsistent parameter estimates because it does not account for
the correlation of the error term with the endogenous variables. In 2SLS or 3SLS, however, each
equation is identified through the inclusion of exogenous variables as instruments that control for
shifts in the supply and demand curves over time.
Exogenous variables influencing the demand for gasoline-powered boats and Small SI
equipment include measures of general economic activity (per capita household or disposable
income, number of households or housing starts). Exogenous variables influencing the cost of
production and supply of boats and Small SI equipment include changes in prices of key inputs
like labor and raw materials.
The supply/demand system for gasoline powered equipment can be defined as follows:
Qtd = f(Pt,Zt) + ut (9E.4)
Qts = g(Pt,Wt) + vt (9E.5)
Q,d = Q,s (9E.6)
Eq. (9E.4) shows quantity demanded as a function of price, Pt; a vector of demand shifters, Zt
(e.g., measures of economic activity); and an error term, ut. Eq. (9E.5) represents quantity
supplied as a function of price and a vector of supply shifters, Wt (e.g., input prices), and an error
9-117
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Draft Regulatory Impact Analysis
term, vt, while Eq. (9E.6) specifies the equilibrium condition that quantity supplied equals
quantity demanded, creating a system of three equations with three endogenous variables. The
interaction of the specified market forces solves this system, generating equilibrium values for
the variables Pt* and Qt* = Qtd* = Qts*.
To generate demand and supply elasticity estimates simultaneously, we used 2SLS and/or
3SLS procedures. For the 2SLS estimates, observed price is regressed against the exogenous
instruments (i.e., the supply and demand "shifter" variables). The fitted (or predicted) values for
the price variable are then employed as observations of the right-hand side price variable in the
supply and demand equations. In the second stage, the 2SLS estimators are generated by running
OLS on these calculated instrumental variables. Also, the 2SLS estimates are used to estimate
errors in the structural equations, which then can be used to estimate the variance-covariance
matrix of the structural equations' errors. For the 3SLS estimates, this information is used at the
third stage to perform a generalized least squares (GLS) estimation of a single large equation
composed from the individual structural equations. If this process is done with all variables
expressed in natural logarithms, the coefficient on the price variable in the demand equation
yields an estimate of the constant elasticity of demand.
9E.2.1 Demand Equation Estimation
Demand equations were estimated using a general specification where the quantity of
boats or Small SI equipment consumed is expressed as a function of price, number of households
or housing starts, per capita household or disposable income, and a time trend. Trends were
included as a general way to model the effects of changes in tastes and preferences. All price and
income variables were deflated by the implicit gross domestic product (GDP) deflator. The
endogenous variables in the equations are unit sales and own-price. The exogenous variables
include the household and income variables and the time trend. The list of instruments includes
these exogenous variables and supply factors influencing the price of the product: wages and a
producer price index for material inputs.
9E.2.2 Data Sets
The National Bureau of Economic Research (NBER) data discussed in the supply
elasticity section of the analysis plan ( RTI, 2005) contain data on production quantities, price
indices, and suitable instruments to inform a demand analysis for recreational boats (SIC 3732).
In its Current Industrial Reports (CIR) series, the U.S. Census Bureau produces an annual
summary of the production of motors and generators and a summary of production of several
types of lawn and garden equipment; both of these reports include the number of units
manufactured and the value of production (U.S. Census Bureau, 1998; 2000). For the
walk-behind lawnmowers regression, we used several data series reported in a study by Air
Improvement Resource, Inc., and National Economic Research Associates (AIR/NERA, 2003).
The U.S. Census Bureau publishes historical data on household income and housing starts (U.S.
Census Bureau, 2002; 2004), and we collected price, wage, and material cost indexes from the
Bureau of Labor Statistics (BLS) (BLS, 2004a,b,c,d,e). Lastly, we obtained an implicit GDP
price deflator from the U.S. Bureau of Economic Analysis (BEA) (BEA, 2004). The following
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Economic Impact Analysis
variables from these sources were used in the regression:
unit sales of boats (Bartlesman et al., 2000),
price index for boats (Bartlesman et al., 2000),
lawn and garden equipment units produced (U.S. Census Bureau, AIR/NERA),
lawn and garden equipment value of production (U.S. Census Bureau),
producer price index for walk-behind lawnmowers (BLS),
households (U.S. Census Bureau),
housing starts (U.S. Census Bureau),
per capita income and population (U.S. Census Bureau, 2002; BEA, 2004),
average hourly earnings for production workers (BLS; Bartlesman et al., 2000),
price index for plastic and other materials and engines (BLS; Bartlesman et al., 2000),
and GDP deflator (BEA).
Some care was needed in using the time series from the CIR data set. Occasional changes
in category definition and the Census Bureau's need to suppress some data to maintain
confidentiality created difficulties in constructing consistent data series over the 2-decade time
period. Nonetheless, we were able to assemble the following series: commercial nonriding
mowers, commercial riding mowers, consumer lawn mowers, tillers and two-wheel tractors,
snow throwers, edgers and trimmers, vacuums and blowers, and lawn and garden tractors.
Statistically significant parameter estimates were obtained for commercial nonriding mowers,
tillers/two-wheel tractors, edgers/trimmers, and lawn and garden tractors.
We were not able to obtain a useful elasticity estimate for consumer lawn mowers using
CIR data, perhaps because of aggregation biases in that category of the CIR data set. Because
consumer lawn mowers are a critical segment of the entire Small SI sector, we used an alternate
data set for our demand elasticity estimate. The data AIR/NERA used in their recent study
proved very useful in this regard (AIR/NERA, 2003). In that study, the authors used a
single-equation OLS regression to obtain a demand elasticity parameter, a procedure that RTI
believes to be inadequate because the market process simultaneously determines price and
quantity in the demand equation. However, using the same data series cited by AIR/NERA
supplemented by data collected by RTI, we were able to obtain a reasonable estimate using the
3SLS regression described above.
9E.2.3 Results of Demand Elasticity Estimation
In this section, we present regression results used in the EIA. Table 9E-8 shows the
parameter estimate for the marine sector, which is -2.0. Although the methodology and data sets
are quite different, this result is consistent with the ones obtained by Raboy (1987) in his study
almost 20 years ago.
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Table 9E-8: Results of Econometric Estimation of Boat Demand Equation: 1958 to 1996
Recreational Boats—SIC 3732
Dependent Variable—Regression Unit Sales per Capita
Intercept -27.9
(-10.3)
Price -2.0
(-2.04)
Disposable income per capita 1.83
(5.85)
Trend -0.19
(-2.15)
Adjusted R2 0.81
Observations (years) 39
(1958-1996)
Notes: 1. Numbers in parentheses are t-ratios (coefficient estimate divided by its standard
error) (except for the year ranges in the last row of the table).
2. All exogenous and endogenous variables are in natural log.
In Table 9E-9, we present demand elasticity results for Small SI equipment. Our estimate
for walk-behind lawnmowers is -0.2 (inelastic). The value obtained for other nonhandheld
categories such as commercial nonriding mowers and lawn and garden tractors is higher at (-0.9,
-1.0). In contrast, the demand estimate for edgers/trimmers is elastic (-1.9), suggesting that
consumers are more willing to forego purchases of these items at higher prices. The
edgers/trimmers' value was used for all handheld equipment. Results for generators, which range
from -1.1 to -1.4, are shown in Table 9E-10.
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Table 9E-9: Results of Econometric Estimation of Small SI Demand
1980 to 1997 (1973-2002 for Consumer Mowers)
Dependent
Variable —
Regression
Method
Intercept
Price
Per capita income
Housing starts per HH (1
lag)
Trend
Adjusted or system
weighted R2
Observations (years)
Consumer Walk-
Behind Mowers
Units Sold per
Household
3SLS
-0.64
(-2.71)
-0.2
(-3.73)
—
0.23
(4.71)
—
0.547
29
(1973-2002)
Commercial
Mowers
Units Produced
2SLS
-35.19
(-4.41)
-0.9
(-2.74)
4.8
(5.76)
—
-0.20
(-1.58)
0.663
18
(1980-97)
Edgers and
Trimmers
Units Produced
2SLS
-4.69
(-0.63)
-1.9
(-6.05)
1.47
(1.79)
—
0.32
(2.52)
0.877
18
(1980-97)
Equations:
Lawn and
Garden Tractors
Units Produced
2SLS
-7.22
(-1.46)
-1.0
(-2.29)
2.2
(4.36)
—
0.02
(0.26)
0.939
18
(1980-97)
Notes: 1. Numbers in parentheses are t-ratios (coefficient estimate divided by its standard error) (except for the
year ranges in the last row of the table).
2. All exogenous and endogenous variables are in natural log.
3. For lawnmowers, the income variable is actually per capita disposable income.
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Table 9E-10: Results of Econometric Estimation of Gasoline-Powered Generators
Demand Equations: 1973 to 1998
Units Produced
Dependent Variable-Regression Small Generators (<5kW) Large Generators (>15kW)
Intercept 16.4 -14.3
(2.64) (-2.48)
Price -1.4 -1.1
(-3.64) (-8.59)
Per capita income -0.46 2.7
(-0.71) (4.34)
Trend -0.02 -0.16
(-0.51) (-1.53)
Adjusted R2 0.609 0.723
Observations (years) 26 26
(1973-1998) (1973-1998)
Notes: 1. Numbers in parentheses are t-ratios (coefficient estimate divided by its standard error) (except for the
year ranges in the last row of the table).
2. All exogenous and endogenous variables are in natural log.
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Appendix 9F: Derivation of Supply Elasticity
In economics, a production function is used to describe the relationship between inputs
and outputs of the production process. The production function in general is defined as follows
Q =f(L, K, M, t)
Q = the quantity of the outputs supplied
L = the labor input or the number of labor hours
K = real capital stock or real capital consumed in the production
M= the material inputs
t = a time trend variable to reflect technology changes
In the competitive market, market forces constrain firms to produce at the cost
minimizing output level. Cost minimization allows for the duality mapping of a firm's
technology (summarized by the firm's production function) to the firm's economic behavior
(summarized by the firm's cost function). The total cost function of an industry in the short term
follows:
TC = h(C,K,t,Qs)
where TC is the total cost of production, C is the variable cost of production (such as the cost of
materials and labor), and the other variables have previous defined. This approach assumes that
capital stock is fixed, or a sunk cost of production. This assumption is consistent with the goal
of the modeling post-control market changes likely to occur. Firms facing proposed regulatory
emission controls will consider embedded capital stock as a fixed or sunk cost in economic
decision making. Differentiating the total cost function with respect to Qs derives the marginal
cost function:
MC= h'(C,K,t,Qs)
where MC is the marginal cost of production and all other variables have been previously
defined.
Profit maximizing competitive firms will choose to produce the quantity of output that
equate the market price (P) to the marginal cost of the production (MC). Setting the price equal
to the preceding marginal cost function and solving for Qs yields the following implied supply
function:
Qs= S(P,PLPM_,K,t,)
where P is the market price of the products, PL is the price of the labor, PM is the price of
materials, and all other variables have been previously defined.
To illustrates how the supply elasticity used in Appendix 9E can be expressed in terms of
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the parameters of the production function (Equation 9E.3), we assume that production function is
represented by a Cobb-Douglas function with only two inputs (capital [K] and labor [L]) with a
constant return to scale,
Q=LaK1-a (9F.1)
where Q = output, L = labor input, and K = capital input. The cost function is written as
TC = wL + rK (9F.2)
where w = wage rate or unit labor cost, r = interest cost or unit capital cost. From equation
(9F.1), L can be written as,
(9F.3)
Substituting L in the cost function with equation (9F.3),
Differentiating cost function with respect to Q, the marginal cost function is
MC = w {(!/ a) Q (1/a) -' K
We have
Q = (a/w)a/ (1-tt) P ttl (1-tt) K (9F.4)
Taking log function on both sides,
lnQ = a/(l-a) In ( afw) + a/(l-a) lnP+ InK (9F.5)
The price elasticity of supply can be written as
Supply elasticity = din Q/ din P = a /(I- a) (9F.6)
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Appendix 9G: Initial Market Equilibrium - Price Forecasts
The EIM analysis begins with current market conditions: equilibrium supply and
demand. To estimate the economic impact of a regulation, standard practice uses projected
market equilibrium (time series of prices and quantities) as the baseline and evaluates market
changes from this projected baseline. Consequently, it is necessary to forecast equilibrium
prices and quantities for future years.
Equilibrium price forecasts typically use one of two approaches (EPA 1999, p 5-25). The
first assumes a constant (real) price of goods and services over time. The second models a
specific time series where prices may change over time due to exogenous factors.
In the absence of shocks to the economy or the supply of raw materials, economic theory
suggests that the equilibrium market price for goods and services should remain constant over
time. As shown in Figure 7G-1, demand grows over time, in the long run, capacity will also
grow as existing firms expand or new firms enter the market and eliminate any excess profits.
This produces a flat long run supply curve. Note that in the short to medium run time frame the
supply curve has a positive slope due to limitations in how quickly firms can react.
S/Q
Short Run
Supply
Short Run
Short Run
Long Run
Supply
Q.
Figure 9G-1. Prices and Quantities in Long Run Market Equilibrium
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If capacity is constrained (preventing the outward shift of the baseline supply curve) or if
the price of production inputs increase (shifting the baseline supply curve upward over time),
then prices may trend upward reflecting that either the growth in demand is exceeding supply or
the commodity is becoming more expensive to produce.
It is very difficult to develop forecasts events (such as those mentioned above) that
influence long run prices. As a result, the approach used in this analysis is to use a constant
2005 observed price.
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Appendix 9H: Sensitivity Analysis
The Economic Impact Analysis presented in this Chapter 9 is based on the Economic
Impact Model (EIM) developed for this analysis. The EIM reflects certain assumptions about
behavioral responses (modeled by supply and demand elasticities), how costs are treated by
producers, what the baseline equipment prices are used in the model. This appendix presents a
sensitivity analysis for several alternatives in the model. Three scenarios are examined:
• Scenario 1: alternative market supply and demand elasticity parameters
• Scenario 2: alternative ways to treat engineering compliance costs
• Scenario 3: alternative baseline prices for lawn mower and tractor
The results of these sensitivity analyses are presented below. The results from Scenario 1
to 3 are presented for 2013 (the highest cost year) only with 2005$. These results for the Small
SI and Marine SI engine and equipment markets do not include the fuel savings. Instead, fuel
savings are added into the total social costs as a separate item.
In general, varying the elasticity parameters does not significantly change the results of
the economic impact assessment analysis presented above. The expected price increase remains
relative stable across the scenarios in comparing with the primary case for the Small SI and
Marine SI engine and equipment. The difference in expected price change between alternative
and primary scenarios is around 0.5 percent. Total social costs are about the same across all
sensitivity analysis scenarios, $507 million. In addition, varying these model parameters does not
significantly affect the way the social costs are borne. In all cases, the end user (households) bear
the majority of the burden (over 70 percent), although there are differences in the way the costs
are borne among the scenarios between the change in either demand or supply elasticity. The
share of social costs end users (households) bear, for example, ranges from 70 to 90 percent.
In the alternative engineering compliance cost scenario, there are differences in the way
the social costs are shared among producers and consumers in the market, although total social
costs are about the same. The share of the social costs borne by either engine manufacturer or
equipment manufacturer increases under this scenario because engines and equipment
manufactures can not recover the fixed cost required in this rule. Especially for the Small SI
market, the difference in the share of social cost borne by engine and equipment manufacturer is
more than 16 percent.
With regard to the scenario of alternative baseline prices, although the difference in
prices is about 25.5% and 53.0% for lawn mower and tractors, respectively, the estimates on
absolute price change and social cost for each market are approximately the same as in the base
case. However, given that the baseline prices are different in these scenarios, there is some
variation in projected relative price and quantity change across the scenarios. The expected
changes in relative prices and quantity increase under the lower alternative baseline market price
scenarios.
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9H.1 Model Elasticity Parameters
Consumer demand and producer supply responsiveness to changes in the commodity
prices are referred to by economists as "elasticity." The measure is typically expressed as the
percentage change in quantity (demanded or supplied) brought about by a percent change in own
price. A detailed discussion regarding the estimation and selection of the elasticities used in the
ELM are discussed in Appendix 9E. This component of the sensitivity analysis examines
the impact of changes in selected elasticity values, holding other parameters constant. The goal
is to determine whether alternative elasticity values significantly alter conclusions in this report.
9H.1.1 Alternative Supply and Demand Elasticity Parameters
The choice of supply and demand elasticities for the engine and equipment market is
important because changes in quantities in the equipment markets are the key drivers in the
derived demand functions used to link impacts in the engine and equipment markets. In addition,
the distribution of regulatory costs depends on the relative supply and demand elasticities used
in
the analysis. For example, consumers will bear less of the regulatory burden if they are more
responsive to price changes than producers.
Table 9H-1 reports the upper- and lower-bound values of the engine and equipment
market elasticity parameters (supply and demand) used in the sensitivity analysis. The engine
and equipment market supply elasticities are derived econometrically. Therefore, the upper and
lower bound values were computed using the coefficient and standard error values associated
with the econometric analysis and reflect a 95 percent confidence interval (see Appendix 9E).
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Table 9H-1: Alternative Supply and Demand Elasticities Used in Sensitivity Analysis51
Parameter/Market
Upper Bound
Primary Case Lower Bound
Supply Elasticities
Engines
Marine and Small SI
4.2
3.*
3.5
Equipment
Marine SI
All other vessel types
PWC
Small SI
Small SI (handheld/nonhandheld)
Gensets/welders
2.5
3.5
3.9
3.6
2.3
3.4
3.4
3.3
2.1
3.2
3.0
2.9
Demand Elasticities
Engines
Marine and Small SI
Derived Demand Derived Demand Derived Demand
Equipment
Marine SI
All vessel types
Small SI
Handheld
Lawn mowers
Other lawn and garden
Gensets/welders — Class I
Gensets/welders — Class II
All other handheld
-3.9
-2.5
-0.3
-1.5
-2.2
-1.4
-1.9
-2.0
-1.9
-0.2
-0.9
-1.4
-1.1
-1.0
-0.1
-1.3
-0.1
-0.3
-0.6
-0.8
-0.1
a EPA computed upper- and lower-bound estimates using the coefficient and standard error values associated with
its econometric analysis and reflect a 95 percent confidence interval (Appendix 9E).
9H.1.2 Engines and Equipment Market (Supply Elasticity Parameters)
The results of the EIM using these alternative supply elasticity values for the Small SI
and Marine SI engine and equipment markets are reported in Tables 9H-2. As can be seen in the
table, projected changes in market prices are stable across the upper- and lower-bound sensitivity
scenarios. The relative change in price is around the primary case by 0.1 percent. Absolute
quantities vary but the percentage changes in output are negligible for the two scenarios. The
change in total social surplus for 2013 also remains nearly unchanged across all scenarios and is
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approximately the same as for the rule ($507 million).
However, varying the supply elasticity changes the social impacts (how the burden is
shared across markets). Manufacturers bear a smaller share of the social costs when they are
more responsive to price changes (supply upper bound scenario). As shown for the Small SI
market, engine and equipment manufacturers bear approximately 3.8 and 16.0 percent,
respectively, in the supply upper bound scenario compared to 4.0 and 17.6 percent in the base
case. In contrast, they bear a higher share of social cost when they are less responsive to price
changes relative to the base case (the supply lower bound scenario). For the Marine SI market,
engine and equipment manufacturers bear approximately 10.8 and 21.6 percent, respectively, in
supply upper bound scenario compared to 11.4 and 22.4 percent in the base case. In contrast,
they bear a higher share when they are less responsive to price changes relative to the base case
(supply lower bound scenario).
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Table 9H-2: Sensitivity Analysis for Engine and Equipment Market Supply Elasticities
for 2013 a b
Scenario
Marine
Market-Level Impacts
Price
Engines
Equipment
Quantity
Engines
Equipment
Welfare Impacts (million S)
Change in engine manufacturers
surplus
Change in equipment manufacturers
surplus
Change in end user (households)
surplus
Small SI
Market-Level Impacts
Price
Engines
Equipment
Class I
Class II
HH
Quantity
Engines
Equipment
Class I
Class H
HH
Welfare Impacts (million $)
Change in engine manufacturers
surplus
Change in equipment manufacturers
surplus
Change in end user (households)
surplus
Subtotal Social Costs (million S)
Fuel Savings (million S)
Total Social Costs (million S)
Primary
Absolute
$256.8
$231.7
-8,846
-10,847
$21.5
$42.2
$125.1
$22.3
$13.8
$18.6
$40.5
$0.3
-371,097
-482,942
-219,400
-157,306
-106,236
$18.4
$80.2
$356.0
$643.4
$136.5
$506.9
Case
Relative"
2.3%
1.3%
-2.0%
-2.7%
11.4%
22.4%
66.2%
11.7%
3.1%
6.9%
3.9%
0.3%
-2.35
-1.9%
-2.2%
-4.3%
-0.6%
4.0%
17.6%
78.3%
Supply Lower Bound
Absolute
$255.1
$222.0
-8,406
-10,443
$22.3
$44.1
$122.7
$22.2
$13.5
$18.3
$39.1
$0.3
-361,097
-467,931
-214,334
-152,207
-101,390
$19.4
$88.1
$347.1
$643.7
$136.5
$507.1
Relative"
2.3%
1.3%
-1.9%
-2.6%
11.8%
23.3%
64.9%
11.7%
3.1%
6.9%
3.8%
0.3%
-2.3%
-1.8%
-2.2%
-4.1%
-0.6%
4.3%
19.4%
76.4%
Supply Upper
Bound
Absolute Relative"
$259.3
$240.8
-9,297
-11,196
$20.4
$40.8
$127.6
$22.3
$14.2
$18.9
$41.6
$0.3
-380,910
-498,041
-224,691
-161,996
-111,354
$17.1
$72.6
$364.6
$643.1
$136.5
$506.6
2.3%
1.4%
-2.1%
-2.8%
10.8%
21.6%
67.6%
11.8%
3.2%
7.0%
4.0%
0.4%
-2.4%
-1.9%
-2.3%
-4.4%
-0. 7%
3.8%
16.0%
80.3%
a Figures are in 2005 dollars.
b For "prices" rows the "relative" column refers to the relative change in price (with regulation) from the baseline
price. For "Surplus" rows, the "relative" column contains the distribution of total surplus changes among
stakeholders (consumers and producers).
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9H.1.3 Equipment Market (Demand Elasticity Parameters)
Sensitivity analysis was also conducted for the equipment market demand elasticities.
The range of demand elasticity values evaluated for each market are provided in Table 9H-1.
The demand elasticities for the engine markets are derived as part of the model, and therefore
sensitivity analysis was not conducted on those parameters.16 In other words, the change in the
equipment market quantities determines the demand responsiveness in the engine market. As a
result, the demand sensitivity analysis for engine markets is indirectly shown in Table 9H-2.
16For a discussion of the concept of derived demand, see Section 9.2.3.2 Incorporating Multimarket
Interactions.
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Table 9H-3: Sensitivity Analysis for Equipment Market Demand Elasticities for 2013
a,b
Scenario
Marine
Market-Level Impacts
Price
Engines
Equipment
Quantity
Engines
Equipment
Welfare Impacts (million S)
Change in engine manufacturers surplus
Change in equipment manufacturers
surplus
Change in end user (households) surplus
Small SI
Market-Level Impacts
Price
Engines
Equipment
Class I
Class II
HH
Quantity
Engines
Equipment
Class I
Class II
HH
Welfare Impacts (million $)
Change in engine manufacturers surplus
Change in equipment manufacturers
surplus
Change in end user (households) surplus
Subtotal Social Costs (million $)
Fuel Savings (million $)
Total Social Costs (million $)
Primary
Absolute
$256.8
$231.7
-8,846
-10,847
$21.5
$42.2
$125.1
$22.3
$13.8
$18.6
$40.5
$0.3
-371,097
^82,942
-219,400
-157,306
-106,236
$18.4
$80.2
$356.0
$643.4
$136.5
$506.9
Case
Relative"
2.3%
1.3%
-2.0%
-2.7%
11.4%
22.4%
66.2%
11.7%
3.1%
6.9%
3.9%
0.3%
-2.35
-1.9%
-2.2%
-4.3%
-0.6%
4.0%
17.6%
78.3%
Demand Lower Bound
Absolute
$301.6
$448.4
-972
-1,016
$2.3
$4.0
$185.7
$23.0
$16.4
$20.4
$46.4
$0.3
-136,358
-219,030
-78,053
-59,011
-81,967
$7.0
$26.1
$424.9
$650.0
$136.5
$513.5
Relative"
2.8%
2.5%
-0.2%
-0.2%
1.2%
2.1%
96.7%
12.1%
3.5%
7.6%
4.4%
0.4%
-0.9%
-0.8%
-1.0%
-3.0%
-0.5%
1.5%
5.7%
92.8%
Demand Upper Bound
Absolute
$242.5
$157.4
-11,205
-14,646
$27.6
$56.2
$103.8
$21.7
$12.1
$17.1
$36.3
$0.3
-542,349
-676,766
-328,416
-222,780
-125,569
$26.3
$116.1
$309.6
$639.6
$136.5
$503.1
Relative"
2.1%
0.9%
-2.6%
-3.6%
14.7%
30.0%
55.3%
11.5%
2.8%
6.4%
3.6%
0.3%
-3.4%
-2.6%
-3.3%
-5.2%
-0.8%
5.8%
25.7%
68.5%
a Figures are in 2005 dollars.
b For "prices" rows the "relative" column refers to the relative change in price (with regulation) from the baseline
price. For "Surplus" rows, the "relative" column contains the distribution of total surplus changes among
stakeholders (consumers and producers).
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As shown in Tables 9H-3, market prices are relative stable across the upper- and lower-
bound sensitivity scenarios. The relative change in price is around the primary case by 0.5
percent. Absolute quantities vary and the percentage changes in output are small for the two
scenarios. There is also a small change in total social surplus for 2013 compared to the primary
case ($507 million) but this is negligible in terms of the percentage change.
In comparing Table 9H-3 with Table 9H-2 , all quantitative estimates for the market
impacts (price and quantity changes) by the EEVI model are a little more sensitive to the
alternative demand elasticities than the alternative supply elasticities. However, theses changes
remain in a reasonable range when compared with the rule, across both the upper and lower
bound demand elasticity scenarios for the equipment markets.
It should be noted, varying the demand elasticity changes the social impacts (how the
burden is shared across markets) as in the case of changing the supply elasticity. Manufacturers
bear a smaller share of the social costs when consumers are less responsive to price changes
(demand lower bound scenario). As shown for the Small SI market, engine and equipment
manufacturers bear approximately 1.5 and 5.7 percent, respectively, in the demand lower bound
scenario compared to 4.0 and 17.6 percent in the base case. In contrast, they bear a higher share
of social cost when consumers are more responsive to price changes relative to the base case (the
demand upper bound scenario). For the Marine SI market, engine and equipment manufacturers
bear approximately 1.2 and 2.1 percent, respectively, in demand lower bound scenario compared
to 11.4 and 22.4 percent in the base case. In contrast, they bear a higher share when consumers
are more responsive to price changes relative to the base case (demand upper bound scenario).
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Economic Impact Analysis
9H.2 Engine and Equipment Variable Cost Shift Scenario
As discussed in Section 9.2, the total costs (fixed plus variable cost) are used to shift the
supply curve in the engines and equipment markets. This is because Small SI and Marine SI
engine and equipment manufacturers produce a product that changes very little over time. These
manufacturers do not engage in research and development to improve their products on a
continuous basis (as opposed to highway vehicles or nonroad engines and equipment). The
product changes that would be required to comply with the proposed standards will require these
manufacturers to devote new funds and resources to product redesign and facilities changes.
Therefore, Small SI and Marine SI engine and equipment manufacturers are expected to increase
their prices by the full amount of the compliance costs to recover those costs. This is in contrast
to the nonroad diesel engine and equipment markets: manufacturers in those markets generally
allocate redesign resources each year to accommodate a changing market. The sensitivity
analysis was performed to investigate the impacts under the alternative scenario of shifting the
supply curve by the variable costs only. The results of that analysis are shown at Table 9H-4.
In this scenario, engine and equipment manufacturers are able to pass along the variable
compliance costs only rather than full costs including the fixed compliance costs. As expected,
this scenario leads to a lower projected price increases for the engine and equipment markets
(from 11.7and3.1 percent in the baseline case to 10.3 and 2.7 percent for Small SI engine and
equipment markets; from 2.3 and 1.3 percent in the baseline case to 2.2 and 1.2 percent for
Marine SI engine and equipment markets). The share of the social costs borne by Small SI
engine and equipment manufacturers are increased by 10.4 and 5.9 percent, respectively. The
share of the social costs borne by Marine SI engine and equipment manufacturers are also
increased by 2.7 and 0.4 percent, respectively. However, the total social costs of the regulation
are not expected to change measurably as the lower prices lead to almost no change in the
demand for equipment and engines.
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Draft Regulatory Impact Analysis
Table 9H-4: Variable Costs only to Shift Supply Curve in Engine and Equipment Markets
for 2013 a b
Scenario
Marine
Market-Level Impacts
Price
Engines
Equipment
Quantity
Engines
Equipment
Welfare Impacts (million $)
Change in engine manufacturers surplus
Change in equipment manufacturers surplus
Change in end user (households) surplus
Small SI
Market-Level Impacts
Price
Engines
Equipment
Class I
Class II
HH
Quantity
Engines
Equipment
Class I
Class II
HH
Welfare Impacts (million $)
Change in engine manufacturers surplus
Change in equipment manufacturers surplus
Change in end user (households) surplus
Subtotal Social Costs (million $)
Fuel Savings (million $)
Total Social Costs (million $)
Fixed and Variable Cost
Supply Shift
Absolute
$256.8
$231.7
-8,846
-10,847
$21.5
$42.2
$125.1
$22.3
$13.8
$18.6
$40.5
$0.3
-371,097
-482,942
-219,400
-157,306
-106,236
$18.4
$80.2
$356.0
$643.4
$136.5
$506.9
Scenario
Relative"
2.3%
1.3%
-2.0%
-2.7%
11.4%
22.4%
66.2%
11.7%
3.1%
6.9%
3.9%
0.3%
-2.35
-1.9%
-2.2%
-4.3%
-0.6%
4.0%
17.6%
78.3%
Variable Cost Only Supply
Shift
Absolute
$245.0
$219.9
-8,264
-10,136
$26.7
$43.0
$119.3
$19.3
$11.0
$16.1
$30.1
$0.3
-309,280
-419,339
-189,939
-125,945
-105,454
$65.8
$107.1
$283.6
$645.5
$136.5
$509.0
Scenario
Relative"
2.2%
1.2%
-1.9%
-2.5%
14.1%
22.8%
63.1%
10.3%
2.7%
6.0%
3.1%
0.3%
-1.9%
-1.6%
-1.9%
-3.3%
-0.6%
14.4%
23.5%
62.1%
a Figures are in 2005 dollars
b For "prices" rows the "relative" column refers to the relative change in price (with regulation) from the baseline
price. For "Surplus" rows, the "relative" column contains the distribution of total surplus changes among
stakeholders (consumers and producers).
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Economic Impact Analysis
9H.3 Alternative Baseline Prices for Lawn Mower & Tractor
As discussed in Section 9.3.2, the starting point for the economic impact analysis is
initial market equilibrium conditions (prices and quantities) that exist prior to the
implementation of new standards. At the pre-control market equilibrium conditions, consumers
are willing to purchase the same amount of a product that producers are willing to produce at the
market price. Since the lawn mower and tractor equipment are the most popular equipment in
the Small SI market and their prices range widely, a sensitivity analysis was performed to
examine how alternative baseline prices for lawn mower and tractor influence the ELM results.
Table 9H-5: Market Sensitivity Analysis for Alternative Baseline for Lawnmower &
Tractor Prices in 2013 a b
Scenario
Lawn Mowers
Primary
scenario
Low price
scenario
Tractors
Primary
scenario
Low price
scenario
Average
Baseline
Price
$243
$181
$1,937
$928
Change in
Price
(Absolute)
$14.38
$14.29
$35.15
$34.69
Market
Change
in Price
5.9%
7.9%
1.8%
3.7%
Results
Change in
Quantity
(Absolute)
-90,263
-120,912
-35,706
-73,559
Change
in
Quantity
-1.1%
-1.5%
-1.8%
-3.7%
Welfare Results
Change in
End Users
(Household
s) Surplus
(Million $)
-$115
-$114
-$69
-$67
Change in
Equipment
Manufacture
r Surplus
(Million $)
-$6
-$6
-$20
-$20
Change in
Total
Surplus
(Million $)
-$121
-$120
-$89
-$87
a Figures are in 2005 dollars.
We selected the lower end market prices as the alternative baseline prices for lawn
mower and tractor in this sensitivity analysis. As shown in Table 9H-5, when these pre-control
baseline prices are allowed to vary, the absolute change in market prices remains nearly
unchanged when compared with the rule, although the relative price change and absolute
quantity change are expected to be higher in the alternative baseline price case. This is because
the change in absolute price is ultimately determined by the per unit compliance cost and market
supply and demand elasticities. In contrast, the change in relative price is determined by the
ratio between the per-unit compliance cost and the baseline price. The lower the initial baseline
price, the higher the ratio is for a given per unit compliance cost. Therefore, the change in the
relative price is higher. In this market, consumers are expected to response to the higher relative
price change by purchasing less equipment. As a result, the expected change for quantity is
higher in the lower baseline prices case. Also as seen in Table 9H-5, varying the baseline prices
are not expected to substantially change the social cost estimates in these markets or alter the
distribution of the social costs across the stakeholders.
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Small-Business Flexibility Analysis
CHAPTER 10: Small-Business Flexibility Analysis
This chapter discusses our Initial Regulatory Flexibility Analysis (IRFA) which evaluates
the potential impacts of the proposed standards on small entities. The Regulatory Flexibility
Act, as amended by the Small Business Regulatory Enforcement Fairness Act of 1996
(SBREFA), generally requires an agency to prepare a regulatory flexibility analysis of any rule
subject to notice and comment rulemaking requirements under the Administrative Procedure Act
or any other statute unless the agency certifies that the rule will not have a significant economic
impact on a substantial number of small entities. Pursuant to this requirement, we have prepared
an IRFA for the proposed rule. Throughout the process of developing the IRFA, we conducted
outreach and held meetings with representatives from the various small entities that could be
affected by the rulemaking to gain feedback, including recommendations, on how to reduce the
impact of the rule on these entities. The small business recommendations stated here reflect the
comments of the small entity representatives (SERs) and members of the Small Business
Advocacy Review Panel (SBAR Panel, or 'the Panel').
10.1 Overview of the Regulatory Flexibility Act
In accordance with section 609(b) of the Regulatory Flexibility Act, we convened an
SBAR Panel before conducting the IRFA. A summary of the Panel's recommendations is
presented in the preamble of this proposed rulemaking. Further, a detailed discussion of the
Panel's advice and recommendations is found in the Final Panel Report contained in the docket
for this proposed rulemaking.
Section 609(b) of the Regulatory Flexibility Act further directs the Panel to report on the
comments of small entity representatives and make findings on issues related to identified
elements of the IRFA under section 603 of the Regulatory Flexibility Act. Key elements of an
IRFA are:
- A description of and, where feasible, an estimate of the number of small entities to
which the proposed rule will apply;
- Projected reporting, record keeping, and other compliance requirements of the proposed
rule, including an estimate of the classes of small entities which will be subject to the
requirements and the type of professional skills necessary for preparation of the report or
record;
- An identification to the extent practicable, of all other relevant Federal rules which may
duplicate, overlap, or conflict with the proposed rule;
- Any significant alternatives to the proposed rule which accomplish the stated objectives
of applicable statutes and which minimize any significant economic impact of the
proposed rule on small entities.
The Regulatory Flexibility Act was amended by SBREFA to ensure that concerns
regarding small entities are adequately considered during the development of new regulations
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Draft Regulatory Impact Analysis
that affect those entities. Although we are not required by the Clean Air Act to provide special
treatment to small businesses, the Regulatory Flexibility Act requires us to carefully consider the
economic impacts that our rules will have on small entities. The recommendations made by the
Panel may serve to help lessen these economic impacts on small entities when consistent with
Clean Air Act requirements.
10.2 Need for the Rulemaking and Rulemaking Objectives
A detailed discussion on the need for and objectives of this proposed rule are located in
the preamble to the proposed rule. As presented in Chapter 8, controlling exhaust and
evaporative emissions from Small SI engines and equipment and Marine SI engines and vessel
has important public health and welfare benefits.
Section 213(a) of the CAA directs EPA to: (1) conduct a study of emissions from
nonroad engines and vehicles; (2) determine whether emissions of CO, NOx, and VOCs from
nonroad engines and vehicles are significant contributors to ozone or CO in more than one area
which has failed to attain the National Ambient Air Quality Standard (NAAQS) for ozone or
CO; and (3) if nonroad emissions are determined to be significant, regulate those categories or
classes of new nonroad engines and vehicles that cause or contribute to such air pollution.
Section 213(a)(3) states that the emission standards "shall achieve the greatest degree of
emission reduction achievable through the application of technology" giving appropriate
consideration to cost, noise, energy, safety, and lead time.
The Nonroad Engine and Vehicle Emission Study required by section 213(a)(l) was
completed in November 1991. The determination of the significance of emissions from nonroad
engines and vehicles in more than one NAAQS nonattainment area was published on June 17,
1994. At the same time, the first set of regulations for new land-based nonroad compression-
ignition (CI) engines at or above 37 kW was promulgated. EPA has also issued proposed or
final rules for most other categories of nonroad engines, including engines used in lawn and
garden equipment, recreational marine vessels, forklifts, recreational vehicles, locomotives, and
ships. In addition, EPA has revised the emission standards for many of these categories of
nonroad engines one or more times to achieve further emission reductions.
In addition to the general authority to regulate nonroad engines under the CAA, section
428 of the Omnibus Appropriations Bill for 2004 requires EPA to propose and finalize new
regulations for nonroad spark-ignition engines less than 50 horsepower (hp). The Bill directs
EPA to propose regulations by December 1, 2004 and finalize them by December 31, 2005.
EPA's assessment of new standards is to be carried out under section 213 of the CAA.
Finally, section 205 of Public Law 109-54 included an additional requirement that EPA
complete a technical study, to look at safety issues related to the potential standards called for
under the Omnibus Appropriations Bill for 2004. The law directed EPA to complete the study
prior to issuing the proposal called for in the Omnibus Appropriations Bill for 2004. In response
to this requirement, EPA prepared a technical study on safety in coordination with the Consumer
Product Safety Commission (CPSC). The study analyzes the incremental risk of fire and burn to
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Small-Business Flexibility Analysis
consumers that could result from the new standards. EPA published the study in March 2006.
In response to these requirements, today's action proposes controls on exhaust and
evaporative emissions from Small SI engines and equipment and Marine SI engines and vessels.
10.3 Definition and Description of Small Entities
Small entities include small businesses, small organizations, and small governmental
jurisdictions. For the purposes of assessing the impacts of the proposed rule on small entities, a
small entity is defined as: (1) a small business that meets the definition for business based on the
Small Business Administration's (SBA) size standards (see Table 10.3-1); (2) a small
governmental jurisdiction that is a government of a city, county, town, school district or special
district with a population of less than 50,000; and (3) a small organization that is any not-for-
profit enterprise which is independently owned and operated and is not dominant in its field.
Table 10.3-1 provides an overview of the primary SBA small business categories potentially
affected by this regulation.
Table 10.3-1: Small Business Definitions for Entities Affected by this Rule
Industry
Nonroad SI Engine Manufacturers
Equipment Manufacturers:
Farm Machinery
Lawn and Garden
Construction
Sawmill and Woodworking
Pumps
Air and Gas Compressors
Generators
Boat Builders
Fuel Tank Manufacturers:
Other Plastic Products
Metal Stamping
Metal Tank (Heavy Gauge)
Fuel Hose Manufacturers:
Rubber and Plastics Hoses
NAICS Codes3
333618
333111
333112
333120
333210
333911
333912
335312
336612
326199
332116
332420
326220
Defined as small entity by
SBA if less than or equal to:b
1,000 employees
500 employees
500 employees
750 employees
500 employees
500 employees
500 employees
1,000 employees
500 employees
500 employees
500 employees
500 employees
500 employees
a North American Industry Classification System
b As defined in SBA's regulations at 13 CFR part 121.
10.3.1 Small SI Engines and Equipment
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Draft Regulatory Impact Analysis
For Small SI engines and equipment, the SB A small business size standards are 1,000
employees for engine manufacturers, 1,000 employees for generator manufacturers, 750
employees for construction equipment manufacturers, and 500 employees for manufacturers of
other types of equipment. To identify companies that meet these criteria, we compiled a list of
engine manufacturers and equipment manufacturers using information from a database prepared
by Power Systems Research (PSR) that contains data on Small SI engines and equipment sold in
the United States. EPA augmented this information with the list of engine manufacturers
currently certifying with EPA under the Small SI engine regulations. We then found
employment data for each company (or parent company if an individual company is part of a
larger group) using databases such as the Thomas Register and Dunn and Bradstreet.
The SB A small business size standard for manufacturers that produce fuel tanks or fuel
hose is 500 employees. To identify companies that meet this criterion, we compiled a list of
manufacturers that produce fuel tanks and fuel hoses for the Small SI equipment market. The list
was based on information from the California Air Resources Board, who has recently adopted
requirements for Small SI engine fuel tank and fuel hose manufacturers, and additional
information from Small SI equipment manufacturers and the Association of Rotational Molders
International. We then found employment data for each of the companies (or parent company if
an individual company is part of a larger group) using databases such as Thomas Register and
onesourceexpress.com and discussions with some of the manufacturers.
10.3.2 Marine SI Engines and Vessels
For Marine SI engines and vessels, the SB A small business size standards are 1,000
employees for engine manufacturers and 500 employees for boat builders. To identify
companies that meet these criteria, we used a number of different sources. For engine
manufacturers, we compiled a list based on the engine manufacturers currently certifying with
EPA and the California Air Resources Board (CARB) under the existing Marine SI engine
regulations and augmented the list with additional information on SD/I manufacturers, who do
not currently have to certify with EPA. We gathered additional information from boat shows,
the Internet, trade magazines, the National Marine Manufacturers Association (NMMA), and
discussions with individual manufacturers. For vessel manufacturers, we used information from
a database of boat builders maintained by the U.S. Coast Guard.
The SB A small business size standard for manufacturers that produce fuel tanks or fuel
hose is 500 employees. For fuel tank and fuel hose manufacturers, we compiled a list based on
information gathered from the NMMA, trade shows, the Internet and discussions with
manufacturers. We then found employment data for these companies (or parent company if an
individual company is part of a larger group) using databases such as Thomas Register and
discussions with trade groups and individual manufacturers.
10.4 Summary of Small Entities to Which the Rulemaking Will Apply
As noted above, for each sector impacted by this proposal, SBA defines small entities by
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Small-Business Flexibility Analysis
number of employees. This section gives an overview of the Small SI engine and equipment
industries and the Marine SI engine and vessel industries, specifically related to small
businesses.
10.4.1 Small SI Engines and Equipment
Based on EPA certification records, the Small SI nonhandheld engine industry is made
up primarily of large manufacturers including Briggs and Stratton, Tecumseh, Honda, Kohler
and Kawasaki. The Small SI handheld engine industry is also made up primarily of large
manufacturers including Electrolux Home Products, MTD, Homelite, Stihl and Husqvarna. EPA
has identified 10 Small SI engine manufacturers that qualify as a small business under SB A
definitions. Half of these small manufacturers certify gasoline engines and the other half certify
liquefied petroleum gas (LPG) engines.
The Small SI equipment market is dominated by a few large businesses including Toro,
John Deere, MTD, Briggs and Stratton, and Electrolux Home Products. While the Small SI
equipment market may be dominated by just a handful of companies, there are many small
businesses in the market; however these small businesses account for less than 10 percent of
equipment sales. We have identified over three hundred equipment manufacturers that qualify as
a small business under the SB A definitions. More than 90 percent of these small companies
manufacture less than 5,000 pieces of equipment per year. The median employment level is 65
employees for nonhandheld equipment manufacturers and 200 employees for handheld
equipment manufacturers. The median sales revenue is approximately $9 million for
nonhandheld equipment manufacturers and $20 million for handheld equipment manufacturers.
EPA has identified 25 manufacturers that produce fuel tanks for the Small SI equipment
market that meet the SB A definition of a small business. Fuel tank manufacturers rely on three
different processes for manufacturing plastic tanks - rotational molding, blow molding and
injection molding. EPA has identified small business fuel tank manufacturers using the
rotational molding and blow molding processes but has not identified any small business
manufacturers using injection molding. In addition, EPA has identified two manufacturers that
produce fuel hose for the Small SI equipment market that meet the SB A definition of a small
business. The majority of fuel hose in the Small SI market is made by large manufacturers
including Avon Automotive and Dana Corporation.
10.4.2 Marine SI Engines and Vessels
Based on EPA certification records, the OB/PWC market is made up primarily of large
manufacturers including, Brunswick (Mercury), Bombardier Recreational Products, Yamaha,
Honda, Kawasaki, Polaris, Briggs & Stratton, Nissan, and Tohatsu. One company that qualifies
as a small business under the SBA definitions has certified their product as a PWC. This
company is Surfango who makes a small number of motorized surfboards.
The SD/I market is made up mostly of small businesses; however, these businesses
account for less than 20 percent of engine sales. Two large manufacturers, Brunswick
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Draft Regulatory Impact Analysis
(Mercruiser) and Volvo Penta, dominate the market. We have identified 28 small entities
manufacturing SD/I marine engines. The third largest company is Indmar, which qualifies as a
small business based on the SB A threshold of 1,000 employees. Based on sales estimates,
number of employees reported by Thomas Register, and typical engine prices, we estimate that
the average revenue for the larger small SD/I manufacturers is about $50-60 million per year.
However, the vast majority of the SD/I engine manufacturers produce low production volumes
of engines and typically have less than 50 employees.
The two largest boat building companies are Brunswick and Genmar. Brunswick owns
approximately 25 boat companies and Genmar owns approximately 12 boat companies. Based
on a manufacturer list maintained by the U.S. Coast Guard, there are over 1,600 boat builders in
the United States. We estimate that, based on manufacturer identification codes, more than
1,000 of these companies produce boats using gasoline marine engines. According to the
National Marine Manufacturers Association (NMMA), most of these boat builders are small
businesses. These small businesses range from individuals building one boat per year to
businesses near the SBA small business threshold of 500 employees.
We have identified 15 marine fuel tank manufacturers in the United States that qualify as
small businesses under the SBA definition. These manufacturers include five rotational molders,
three blow molders, six aluminum fuel tank manufacturers, and one specialty fuel tank
manufacturer. The small rotational molders average less than 50 employees while the small
blow-molders average over 100 employees. Moeller qualifies as a large business because they
are owned by Moore; however, their rotational molding business is a small part of the company
and operates similar to the smaller businesses. Other blow-molders are in the same situation
such as Attwood which is owned by Brunswick.
We have only identified one small hose manufacturer that produces for the Marine SI
market. Novaflex primarily distributes hoses made by other manufacturers, but does produce its
own fill neck hose. Because we expect vessel manufacturers will design their fuel systems such
that there will not be standing liquid fuel in the fill neck (and therefore the proposed low
permeation fuel hose requirements will not apply to the fill neck), we have not included this
manufacturer in our analysis. The majority of fuel hose in the Marine SI market is made by large
manufacturers including Goodyear and Parker-Hannifm.
10.5 Related Federal Rules
For Small SI engines and equipment, the primary federal rules that are related to the rule
under consideration are EPA Phase 1 rule for Small SI engines (60 FR 34582, July 3, 1995),
EPA Phase 2 rule for Small SI nonhandheld engines (64 FR 15208, March 30, 2004), and EPA
Phase 2 rule for Small SI handheld engines (65 FR 24268, April 25, 2000). For Marine SI
engines and vessels, the primary federal rule that is related to the rule under consideration is
EPA October 1996 final rule (61 FR 52088, October 4, 1996).
Three other federal agencies have regulations that relate to the equipment and vessels
under consideration. These agencies are the Consumer Product Safety Commission (CPSC),
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Small-Business Flexibility Analysis
United States Department of Agriculture (USDA), and the United States Coast Guard (USCG).
CPSC has safety requirements that apply to walk-behind lawnmowers to protect operators of
such equipment. USDA has design requirements intended to reduce the potential fire threat of
Small SI equipment. The USCG has safety regulations for marine engine and fuel system
designs. The USCG safety regulations include standards for exhaust system temperature, fuel
tank durability, and hose designs, including specific requirements related to system survivability
in a fire. Manufacturers will need to consider both EPA and other federal standards when
certifying their products.
10.6 Projected Reporting, Recordkeeping, and Other Compliance
Requirements
For any emission control program, EPA must have assurances that the regulated products
will meet the standards. Historically, EPA programs for Small SI engines and Marine SI
engines have included provisions placing engine manufacturers responsible for providing these
assurances. The program that EPA is considering for manufacturers subject to this proposal may
include testing, reporting, and record keeping requirements for manufacturers of engines,
equipment, and vessels, and may also include fuel system component manufacturers if they
choose to certify their fuel tank, fuel hose, and fuel cap products.
For Small SI engine manufacturers and OB/PWC engine manufacturers, EPA is
proposing to continue the same reporting, record keeping, and compliance requirements
prescribed in the current regulations. For SD/I engine manufacturers, which are not currently
subject to EPA regulation, EPA is proposing to apply similar reporting, record keeping, and
compliance requirements to those for OB/PWC engine manufacturers. Testing requirements for
engine manufacturers would include certification emission (including deterioration factor)
testing and production line testing. Reporting requirements would include emission test data and
technical data on the engines. Manufacturers would also need to keep records of this
information.
Because of the proposed evaporative emission requirements, there would be new
reporting, record keeping and compliance requirements for Small SI equipment manufacturers.
Small SI equipment manufacturers participating in the proposed transition program would also
be subject to reporting, record keeping and compliance requirements. Depending on who
chooses to certify fuel system components, there may also be new reporting, record keeping and
compliance requirements for fuel tank manufacturers, fuel hose manufacturers, fuel cap
manufacturers, and marine vessel manufacturers. Testing requirements for these manufacturers
could include certification emission testing. Reporting requirements could include emission test
data and technical data on the designs. Manufacturers would also need to keep records of this
information.
10.7 Regulatory Alternatives
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Draft Regulatory Impact Analysis
The Panel developed a wide range of regulatory alternatives to mitigate the impacts of
the rulemaking on small businesses, and recommended that we propose and seek comment on
the flexibilities. The Panel's findings and discussions are based on the information that was
available during the term of the Panel and issues that were raised by the SERs during the
outreach meetings and in their written comments. It was agreed that EPA should consider the
issues raised by the SERs (and issues raised in the course of the Panel) and that EPA should
consider the comments on flexibility alternatives that would help to mitigate any negative
impacts on small businesses. Alternatives discussed throughout the Panel process include those
offered in the development of the upcoming rule. Though some of the recommended flexibilities
may be appropriate to apply to all entities affected by the rulemaking, the Panel's discussions
and recommendations are focused mainly on the impacts, and ways to mitigate adverse impacts,
on small businesses. A summary of the Panel's recommendations, along with those provisions
that we are actually proposing in this action, are detailed below. A full discussion of the
regulatory alternatives and hardship provisions discussed and recommended by the Panel, all
written comments received from SERs, and summaries of the two outreach meetings that were
held with the SERs can be found in the SBREFA Final Panel Report.1 In addition, all of the
flexibilities that are being proposed in the rulemaking for small businesses, as well as those for
all entities that may be affected by the rulemaking, are described in the preamble to the proposed
rule.
10.7.1 Small SI Exhaust Emission Standards
Described below are the flexibility options recommended by the Panel and our proposed
regulatory alternatives related to the Small SI nonhandheld engine exhaust emission standards.
10.7.1.1 Regulatory Flexibility Options for Nonhandheld Engine Manufacturers
10.7.1.1.1 SBAR Panel Recommendations
Additional Lead Time for Nonhandheld Engine Manufacturers - The Panel
recommended that EPA propose two additional years of lead time before the Phase 3 standards
take effect for small business engine manufacturers. For Class I engines, the effective date for
small business engine manufacturers would be 2014. For Class II engines, the effective date for
small business engine manufacturers would be 2013.
Assigned Deterioration Factors - The Panel recommended EPA propose that small
business engine manufacturers be allowed the option to use EPA-developed assigned
deterioration factors in demonstrating compliance with the Phase 3 exhaust emission standards.
Production Line Testing Exemption - The Panel recommended EPA propose that small
business engine manufacturers be exempted from the production line testing requirements for the
Phase 3 exhaust emission standards.
Broader Definition of Engine Family - The Panel recommended that EPA propose
allowing small business engine manufacturers to group all of their Small SI engines into a single
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Small-Business Flexibility Analysis
engine family for certification by engine class and useful life category, subject to good
engineering judgment.
Eligibility for the Small Business Flexibilities - For purposes of determining which
engine manufacturers are eligible for the small business flexibilities described above, EPA is
proposing criteria based on a production cut-off of 10,000 nonhandheld engines per year for
engine manufacturers. The Panel recommended that EPA propose to allow engine
manufacturers which exceed the production cut-off levels noted above but meet the SB A
definitions for a small business (i.e., fewer than 1,000 employees for engine manufacturers), to
request treatment as a small business.
10.7.1.1.2 EPA's Proposed Regulatory Flexibility Options
In general, we have chosen to propose the Panel's recommended regulatory flexibility
provisions. The following is a discussion of the proposed provisions.
Additional Lead Time for Nonhandheld Engine Manufacturers - We are proposing that
small-volume engine manufacturers could delay implementation of the Phase 3 exhaust emission
standards for two years (see §1045.145). Small-volume engine manufacturers would be required
to comply with the Phase 3 exhaust emission standards beginning in model year 2014 for Class I
engines and model year 2013 for Class II engines. Under this approach, we propose that
manufacturers would be able to apply this delay to all their nonhandheld engines or to just a
portion of their production. They could therefore sell engines that meet the Phase 3 standards on
some product lines while delaying introduction of emission control technology on more
challenging product lines. This option provides more time for small-volume engine
manufacturers to redesign their products. They would also be able to learn from some of the
hurdles overcome by larger manufacturers.
Assigned Deterioration Factors - We are proposing that small-volume engine
manufacturers may rely on an assigned deterioration factor to demonstrate compliance with the
standards rather than doing service accumulation and additional testing to measure deteriorated
emission levels at the end of the regulatory useful life (see §1054.240). EPA is not proposing
actual levels for the assigned deterioration factors with this proposal. EPA intends to analyze
emissions deterioration information that becomes available over the next few years to determine
what deterioration factors would be appropriate for nonhandheld engines. This data is likely to
include deterioration data for engines certified to comply with CARB's Tier 3 standards and
engines certified early to EPA's Phase 3 standards. Prior to the implementation date for the
Phase 3 standards, EPA would provide guidance to engine manufacturers specifying the levels of
the assigned deterioration factors for small-volume engine manufacturers.
Production Line Testing Exemption - We are proposing that small-volume engine
manufacturers would be exempt from the production-line testing requirements (see §1054.301).
While we are proposing to exempt small volume engine manufacturers from production line
testing, we believe requiring limited production-line testing could be beneficial to remind
manufacturers they have an ongoing obligation to assure production engines are complying with
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Draft Regulatory Impact Analysis
the standards. Therefore, we request comment on the alternative of applying limited production-
line testing to small volume engine manufacturers with a requirement to test one production
engine per year.
Broader Definition of Engine Family - We are proposing that small-volume engine
manufacturers may use a broader definition of engine family for certification purposes. Under
the existing engine family criteria specified in the regulations, manufacturers group their various
engine lines into engine families that have similar design characteristics including the
combustion cycle, cooling system, cylinder configuration, number of cylinders, engine class,
valve location, fuel type, aftertreatment design, and useful life category. We are proposing to
allow small-volume engine manufacturers to group all of their Small SI engines into a single
engine family for certification by engine class and useful life category, subject to good
engineering judgment (see §1054.230).
Eligibility for the Small Business Flexibilities - We are proposing to retain the current
criteria (i.e., 10,000 units per year of nonhandheld engines) for determining who is a small-
volume engine manufacturer and, as a result, eligible for the Phase 3 flexibilities described above
(see §1054.801). Based on confidential sales data provided to EPA by engine manufacturers, the
10,000 unit cut-off for engine manufacturers would include all of the small business engine
manufacturers using SBA's employee-based definition. However to ensure all small businesses
that meet SBA's employee-based definition have access to the flexibilities described below, EPA
is also proposing to allow engine manufacturers which exceed the production cut-off level noted
above but have fewer than 1,000 employees, to request treatment as a small volume engine
manufacturer (see §1054.635). In such a case, the manufacturer would need to provide
information to EPA demonstrating that the manufacturer has fewer employees than the 1,000
cut-off level established by SB A.
10.7.1.2 Regulatory Flexibility Options for Nonhandheld Equipment Manufacturers
10.7.1.2.1 SBAR Panel Recommendations
Additional Lead Time for Small SI Equipment Manufacturers - The Panel
recommended that EPA propose a transition program that would allow small business equipment
manufacturers to continue using Phase 2 engine designs (i.e., engines meeting the Phase 2
exhaust emission standards) during the first two years that the Phase 3 standards take effect.
(For equipment using Class I engines, the provision would apply in 2012 and 2013. For
equipment using Class II engines, the provision would apply in 2011 and 2012.) The Panel also
recommended that EPA propose to allow small business equipment manufacturers to use Phase 3
engines without the catalyst during this initial two year period, provided the engine manufacturer
has demonstrated that the engine without the catalyst would comply with the Phase 2 exhaust
emission standards and labels it appropriately.
Simplified Engine Certification for Equipment Manufacturers - Generally, it has been
engine manufacturers who certify with EPA for the exhaust emission standards, where the
standards are engine standards. However, a number of equipment manufacturers, especially
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those that make low-volume models, believe it may be necessary for equipment manufacturers to
certify their own unique engine/muffler designs with EPA (but using the same catalyst substrate
already used in a muffler certified by the engine manufacturer. The Panel recommended that
EPA propose a simplified engine certification process for small business equipment
manufacturers in such situations. Under such a simplified certification process, the equipment
manufacturer would need to demonstrate that it is using the same catalyst substrate as the
approved engine manufacturer's family, provide information on the differences between their
engine/exhaust system and the engine/exhaust system certified by the engine manufacturer, and
explain why the deterioration data generated by the engine manufacturer would be representative
for the equipment manufacturer's configuration.
Eligibility for the Small Business Flexibilities - For purposes of determining which
equipment manufacturers are eligible for the small business flexibilities described above, EPA is
proposing criteria based on a production cut-off of 5,000 pieces of nonhandheld equipment per
year for equipment manufacturers. The Panel recommended that EPA propose to allow
equipment manufacturers which exceed the production cut-off levels noted above but meet the
SBA definitions for a small business (i.e., fewer than 500 employees for most types of equipment
manufacturers), to request treatment as a small business.
10.7.1.2.2 EPA's Proposed Regulatory Flexibility Options
In general, we have chosen to propose the Panel's recommended regulatory flexibility
provisions. The following is a discussion of the proposed provisions.
Additional Lead Time for Small SI Equipment Manufacturers - We are proposing that
small-volume equipment manufacturers would have two extra years beyond the implementation
dates for the Phase 3 standards to continue using Phase 2 engines in their Class II equipment.
Alternatively, the manufacturer could use Phase 3 engines without the catalysts, provided the
engine manufacturer submitted data at the time of certification showing that the engine without
the catalyst complied with EPA's Phase 2 standards. As described in Section V.E.3 of the
preamble, EPA is proposing a flexibility program for all equipment manufacturers that produce
Class II equipment. Under that program, equipment manufacturers can install Phase 2 engines in
limited numbers of Class II equipment over the first four years the Phase 3 standards apply (i.e.,
2011 through 2015). The number of equipment that can use Phase 2 engines is based on 30
percent of an average annual production level of Class II equipment. In an effort to provide
additional flexibility to small-volume equipment manufacturers within the context of the
flexibility program, EPA is proposing that small-volume manufacturers may use Phase 2 engines
at a level of 200 percent of an average annual production level of Class II equipment over the
four year period (see §1054.625). Therefore, a small-volume equipment manufacturer could
potentially use Phase 2 engines on all their Class II equipment for two years (consistent with the
SBAR Panel's recommendation) or they might, for example, sell half their Class II equipment
with Phase 2 engines for four years.
Simplified Engine Certification for Equipment Manufacturers - We are proposing a
simplified engine certification procedure for small-volume equipment manufacturers. (As
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discussed in Section V.E.4 of the preamble, we are also proposing this provision for other
manufacturers, regardless of the company's size.) Generally, it has been engine manufacturers
who certify with EPA for the exhaust emission standards because the standards are engine-based
standards. However, because the Phase 3 standards under consideration are expected to result in
the use of catalysts, a number of equipment manufacturers, especially those that make low-
volume models, believe it may be necessary to certify their own unique engine/muffler designs
with EPA, but using the same catalyst substrate already used in a muffler certified by the engine
manufacturer. In order to allow the possibility of an equipment manufacturer certifying an
engine/muffler design with EPA, we are proposing a simplified engine certification process for
small-volume equipment manufacturers (see §1054.612). Under such a simplified certification
process, the equipment manufacturer would need to demonstrate that it is using the same catalyst
substrate as the approved engine manufacturer's family, provide information on the differences
between their engine/exhaust system and the engine/exhaust system certified by the engine
manufacturer, and explain why the emissions deterioration data generated by the engine
manufacturer would be representative for the equipment manufacturer's configuration.
Eligibility for the Small Business Flexibilities - EPA is proposing to retain the current
criteria (i.e., 5,000 units per year of nonhandheld equipment) for determining who is a small-
volume equipment manufacturer and, as a result, eligible for the Phase 3 flexibilities described
above (see §1054.801). Based on sales data, the 5,000 unit cut-off for equipment manufacturers
would include the vast majority of the small business equipment manufacturers using SBA's
employee-based definition. However to ensure all small businesses that meet SBA's employee-
based definition have access to the flexibilities described below, EPA is also proposing to allow
equipment manufacturers which exceed the production cut-off level noted above but have fewer
employees than the SBA definition of small business (i.e., 500 employees for manufacturers of
most types of equipment), to request treatment as a small-volume equipment manufacturer (see
§1054.635). In such a case, the manufacturer would need to provide information to EPA
demonstrating that the manufacturer has fewer employees than the applicable employee cut-off
level established by SBA.
10.7.2 Marine SI Exhaust Emission Standards—Regulatory Flexibility Options for SD/I
Engine Manufacturers
Described below are the flexibility options recommended by the Panel and our proposed
regulatory alternatives related to the exhaust emission standards for marine SD/I engine
manufacturers.
10.7.2.1 SBAR Panel Recommendations
Additional Lead Time for SD/I Engine Manufacturers - The Panel recommended that
EPA propose an implementation date of 2011 for <373 kW SD/I engines produced by small
business marine engine manufacturers and an implementation date of 2013 for small business
manufacturers of high performance (>373 kW) SD/I marine engines. Based on the proposed
2009 implementation date for the remaining SD/I engine manufacturers (i.e., the large
businesses), these dates would provide small business SD/I engine manufacturers with 2 years
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additional lead time for <373 kW SD/I engines and 4 years additional lead time for >373 kW
SD/I engines.
Exhaust Emission ABT - EPA is proposing an averaging, banking and trading (ABT)
program for the SD/I engine standards. Because EPA is proposing an ABT program for SD/I
engines, the Panel recommended that EPA request comment on the desirability of credit trading
between high performance and other SD/I marine engines and the impact it could have on small
business.
Early Credit Generation for ABT - EPA is proposing an early banking program for SD/I
marine engines. Under the early banking provisions, manufacturers can generate "bonus" credits
for the early introduction of engines meeting the proposed emission standards. The Panel
supports EPA proposing an early banking program and believes that bonus credits will provide
greater incentive for more small business engine manufacturers to introduce advanced
technology earlier than would otherwise occur.
Assigned Emission Rates for High Performance (>373 kW) SD/I Engines - The Panel
recommended that EPA propose to allow the use of default emission rates that could be used by
small business high performance SD/I engine manufacturers as part of their certification. Based
on currently available test data, the proposed default baseline emission levels for high
performance engines are 30 g/kW-hr HC+NOx and 350 g/kW-hr CO.
Alternative Standards for Hieh Performance (>373 kW) SD/I Engines - SERs
expressed concern that that catalysts have not been demonstrated on high performance engines
and that they may not be practicable for this application. While EPA is proposing a standard
based on the use of catalysts, EPA is requesting comment on a standard for high performance
SD/I marine engines that could be met without the use of a catalyst. (Based on available data,
levels of 16 g/kW-hr HC+NOx and 350 g/kW-hr CO were discussed with the SERs). The Panel
recommended EPA request comment on a non-catalyst based standard for high performance
marine engines.
EPA is proposing to not apply the not-to-exceed (NTE) standards to high performance
SD/I engines. The Panel supports excluding high performance SD/I engines from NTE
requirements.
Broad Engine Families for High Performance (>373 kW) SD/I Engines - The Panel
recommended that EPA propose allowing small businesses to group all of their high performance
SD/I engines into a single engine family for certification, subject to good engineering judgment.
Simplified Test Procedures for High Performance (>373 kW) SD/I Engines - For high
performance SD/I engines, it may be difficult to hold the engine at idle or high power within the
tolerances currently specified in existing EPA test procedures. The Panel recommended that
EPA propose less restrictive specifications and tolerances for small businesses testing high
performance SD/I engines, which would allow the use of portable emission measurement
equipment.
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Eligibility for the Small Business Flexibilities - For purposes of determining which
engine manufacturers are eligible for the small business flexibilities described above for SD/I
engine manufacturers, EPA is proposing criteria based on a production cut-off of 5,000 SD/I
engines per year. The Panel recommended EPA propose to allow engine manufacturers that
exceed the production cut-off level noted above but meet the SB A definitions for a small
business (i.e., fewer than 1,000 employees for engine manufacturers), to request treatment as a
small business.
10.7.2.2 EPA's Proposed Regulatory Flexibility Options
In general, we have chosen to propose the Panel's recommended regulatory flexibility
provisions. The following is a discussion of the proposed provisions.
Additional Lead Time for SD/I Engine Manufacturers - One small business marine
engine manufacturer is already using catalytic converters on some of its <373 kW production
SD/I marine engines. These engines have been certified to meet standards adopted by CARB
that are roughly equivalent to the proposed standards. However, other small businesses
producing SD/I engines have stated that they are not as far along in their catalyst development
efforts. These manufacturers support the concept of receiving additional time for compliance,
beyond the implementation date for large manufacturers. For these reasons, EPA is proposing an
implementation date of 2011 for <373 kW SD/I engines produced by small business marine
engine manufacturers and a date of 2013 for small business manufacturers of high-performance
(>373 kW) marine engines (see §1045.145).
Exhaust Emission ABT - We are proposing an averaging, banking, and trading (ABT)
credit program for exhaust emissions from SD/I marine engines (see part 1045, subpart H).
Small businesses expressed some concern that ABT could give a competitive advantage to large
businesses. Specifically, there was an equity concern that if credits generated by traditional
(<373 kW) SD/I engines could be used for high-performance SD/I engines, that one large
manufacturer could use these credits to meet the high-performance SD/I engine standards
without making any changes to their engines. In response, EPA is requesting comment on the
desirability of credit trading between high-performance and other SD/I marine engines and the
impact it could have on small business.
Early Credit Generation for ABT - We are proposing an early banking program in which
bonus credits can be earned for certifying early (see §1045.145). This program, combined with
the additional lead time for small businesses, would give small-volume SD/I engine
manufacturers ample opportunity to bank emission credits prior to the proposed implementation
date of the standards and provide greater incentive for more small business engine manufacturers
to introduce advanced technology earlier than would otherwise occur.
Assigned Emission Rates for High Performance (>373 kW) SD/I Engines - We are
proposing assigned baseline HC+NOx and CO emission rates for all high-performance SD/I
engines. These assigned emission rates are based on test data presented in Chapter 4 of the draft
RIA. We are also proposing assigned deterioration factors for small-volume high-performance
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SD/I manufacturers. (See §1045.240.)
Alternative Standards for High Performance (>373 kW) SD/I Engines - Small
businesses expressed concern that that catalysts have not been demonstrated on high-
performance engines and that they may not be practicable for this application. In addition, the
concern was expressed that emission credits may not be available at a reasonable price. In
response, we are requesting comment on the need for and level of alternative standards for high-
performance marine engines. Also, we are not proposing to apply NTE standards to high-
performance SD/I engines (See §1045.105).
Broad Engine Families for High Performance (>373 kW) SD/I Engines - Typically in
EPA engine and equipment programs, manufacturers are able to group their engine lines into
engine families for certification to the standards. Engines in a given family must have many
similar characteristics including the combustion cycle, cooling system, fuel system, air
aspiration, fuel type, aftertreatment design, number of cylinders and cylinder bore sizes. A
manufacturer would then only perform emission tests on the engine in that family that would be
most likely to exceed an emission standard. We are proposing to allow small businesses to
group all of their high performance SD/I engines into a single engine family for certification,
subject to good engineering judgment (see §1045.230).
Simplified Test Procedures for High Performance (>373 kW) SD/I Engines - Existing
testing requirements include detailed specifications for the calibration and maintenance of testing
equipment and tolerances for performing the actual tests. For high performance SD/I engines, it
may be difficult to hold the engine at idle or high power within the tolerances currently specified
by EPA in the test procedures. Therefore, we are proposing less restrictive specifications and
tolerances, for small businesses testing high performance SD/I engines, which would allow the
use of portable emission measurement equipment (see §1065.901(b)). This would facilitate less
expensive testing for these small businesses without having a negative effect on the environment.
Eligibility for the Small Business Flexibilities - For purposes of determining which
engine manufacturers are eligible for the small business flexibilities described above for SD/I
engine manufacturers, we are proposing criteria based on a production cut-off of 5,000 SD/I
engines per year. Under this approach, we would allow engine manufacturers that exceed the
production cut-off level noted above to request treatment as a small business if they have fewer
than the number of employees specified above under the SB A definition of small business. In
such a case, the manufacturer would need to provide information to EPA demonstrating that the
manufacturer has fewer employees than the applicable employee cut-off level established by
SBA.
10.7.3 Small SI and Marine SI Evaporative Emission Standards— Flexibility Alternatives
for Equipment, Vessel, and Fuel Tank Manufacturers
Described below are the flexibility options recommended by the Panel and our proposed
regulatory alternatives related to the evaporative emission standards for Small SI engines and
equipment and Marine SI engines and vessels. SERs raised many of the same issues regarding
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Draft Regulatory Impact Analysis
evaporative emission standards for both Small SI and marine applications. In fact, many of the
SERs supply fuel system components to both industries. For these reasons, the Panel's
recommendations on regulatory flexibility discussed below would apply to Small SI equipment
and to SD/I marine vessels, except where noted.
Because the majority of fuel tanks produced for the Small SI equipment and the SD/I
marine vessel market are made by small businesses, the details of the evaporative emissions
program under consideration and the flexibility provisions shared by EPA with the SERs were
noted as being available to all fuel tank manufacturers. Therefore, EPA is proposing the Panel
recommendations on regulatory flexibility discussed below for small business fuel tank
manufacturers for all fuel tank manufacturers.
10.7.3.1 SBAR Panel Recommendations
Consideration of Appropriate Lead Time - The Panel recommended that EPA propose to
implement the fuel tank permeation standards in 2011 with an additional year (2012) for
rotationally-molded marine fuel tanks. The extra year for rotational-molded marine tanks would
give manufacturers time to address issues that are specific to the marine industry.
With regard to diurnal emissions control, SERs commented that they would like
additional time to install carbon canisters in their vessels because of deck and hull changes that
might be needed to accommodate the carbon canisters. SERs commented that they would
consider asking EPA to allow the use of low permeation fuel hose prior to 2009 as a method of
creating an emission neutral flexibility option for providing extra time for canisters. The Panel
recommended that EPA continue discussions with the marine industry and request comment on
environmentally neutral approaches to provide more flexibility in meeting the potential diurnal
emission standards.
Fuel Tank ABT and Early Incentive Program - The Panel recommended that EPA
propose an ABT program for fuel tank permeation. The Panel also recommended that EPA
request comment on including service tanks (i.e., replacement tanks) in the ABT program.
Finally, the Panel recommended that EPA request comment and on an early incentive program
for tank permeation.
Broad Definition of Evaporative Emission Family for Fuel Tanks - The Panel
recommended that EPA propose a broad emission family definition for Small SI fuel tanks and
for marine fuel tanks similar to that in the regulations for recreational vehicles. Under the
recreation vehicle evaporative emission regulations, EPA specifies that fuel tank permeation
emission families be based on type of material (including additives such as pigments,
plasticizers, and ultraviolet (UV) inhibitors), emission-control strategy, and production methods.
Fuel tanks of different sizes, shapes, and wall thicknesses may be grouped into the same
emission family.
Compliance Progress Review for Marine Fuel Tanks - While there is clearly a
difference of opinion among the SERs involved in tank manufacturing, some SERs expressed
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Small-Business Flexibility Analysis
concern that there is not an established low permeation technology available for rotationally-
molded marine fuel tanks. These SERs stated that they are working on developing such
technology, but do not have in-use experience to demonstrate the durability of low-permeation
rotationally molded fuel tanks. The Panel recommended that if a rule is implemented, EPA
undertake a "compliance progress review" assessment with the manufacturers. In this effort,
EPA should continue to engage on a technical level with rotationally-molded marine fuel tank
manufacturers and material suppliers to assess the progress of low permeation fuel tank
development and compliance.
Design-Based Certification - The Panel recommended that EPA propose a design-based
certification for carbon canisters and fuel tanks. For the carbon canisters, the design requirement
would call for a ratio of carbon volume (liters) to fuel tank capacity (gallons) of 0.04 liter/gallon
for boats less than 26 feet in length, and 0.016 liter/gallon for larger boats. The different canister
sizes are intended to account for the difference between boats normally trailered to the water for
use versus boats normally stored in the water between uses. For fuel tanks, the Panel
recommended that EPA propose to allow design-based certification for metal tanks and plastic
fuel tanks with a continuous EVOH barrier.
SERs commented that the American Boat and Yacht Council (AB YC) and the Society of
Automotive Engineers (SAE) have industry recommended practices for boat designs that must
be met as a condition of membership in the National Marine Manufacturers Association
(NMMA). NMMA is working to update these recommended practices to include carbon canister
installation specifications and a low-permeation hose designation. The Panel recommended that
EPA propose to accept data used for meeting the voluntary requirements as part of the EPA
certification.
Additional Lead Time for Small SI Fuel Hose Requirement - EPA is proposing to apply
the fuel hose permeation requirements beginning with the 2008 model year for Small SI
nonhandheld equipment. Given the short lead time before 2008, small business equipment
manufacturers may not be ready for such a requirement. The Panel recommended EPA propose
a 2009 implementation date for low permeation fuel hose for small business equipment
manufacturers producing Small SI nonhandheld equipment.
10.7.3.2 EPA's Proposed Regulatory Flexibility Options
In general, we have chosen to propose the Panel's recommended regulatory flexibility
provisions. The following is a discussion of the proposed provisions.
Consideration of Appropriate Lead Time - Consistent with the Panel recommendations,
we are proposing to implement the tank permeation standards in 2011 with an additional year
(2012) for rotational-molded marine fuel tanks (see §1054.110 and §1045.107). With regard to
the proposed diurnal emission control requirements, we are requesting comment on
environmentally neutral approaches to provide more flexibility in meeting the potential diurnal
emission standards.
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Fuel Tank ABT and Early Incentive Program - Consistent with the Panel
recommendations, we are proposing an ABT program for fuel tank permeation and an early-
allowance program for fuel tank permeation. We are requesting comment on including service
tanks in the ABT program. Service tanks are fuel tanks sold as replacement parts for in-use
equipment.
Broad Definition of Evaporative Emission Family for Fuel Tanks - We are proposing
that permeation emission families be based on type of material (including additives such as
pigments, plasticizers, and UV inhibitors), emission-control strategy, and production methods.
Fuel tanks of different sizes, shapes, and wall thicknesses could be grouped into the same
emission family (see §1045.230 and §1054.230). Manufacturers therefore would be able to
broadly group similar fuel tanks into the same emission family and then only test the
configuration most likely to exceed the emission standard. Although Small SI and Marine SI
fuel tanks would not be allowed in the same emission family, it would be possible to carry-across
certification test data from one category to another.
Compliance Progress Review for Marine Fuel Tanks - Some major manufacturers of
rotational-molded marine fuel tanks have expressed concern that they do not have significant in-
use experience to demonstrate the durability of low-permeation rotational-molded fuel tanks in
boats. However, one manufacturer of rotational-molded fuel tanks has stated that they are
already selling low permeation tanks into the Small SI market and they have plans to sell them
into marine applications. To address this uncertainty, EPA notes in the preamble for the rule that
it intends to continue to engage on a technical level with rotational-molded marine fuel tank
manufacturers and material suppliers to assess the progress of low permeation fuel tank
development and compliance. If systematic problems are identified across the industry, this
would give EPA the opportunity to address the problem. If problems were identified only for
individual businesses, this would give EPA early notice of the issues that may need to be
addressed through the proposed hardship relief provisions.
Design-Based Certification - We are proposing design-based certification for carbon
canisters for boats. For the carbon canisters, the design requirement would call for a ratio of
carbon volume (liters) to fuel tank capacity (gallons) of 0.04 liter/gallon for boats less than 26
feet in length, and 0.016 liter/gallon for larger boats. We are also proposing design-based
certification for certain fuel tanks. For fuel tanks, we are proposing to allow design-based
certification for metal tanks as well as plastic fuel tanks with a continuous EVOH barrier. With
regard to the Panel recommendation that EPA accept data for its certification program that is
used for meeting industry recommended practices (such as those recommended by NMMA,
ABYC and SAE), we are proposing that this data could be used as part of EPA certification as
long as it is collected consistent with the test procedures and other requirements proposed today.
Additional Lead Time for Small SI Fuel Hose Requirement - We are proposing an
implementation date of 2008 for Small SI hose permeation standards for non-handheld
equipment (see §90.127). Consistent with the Panel recommendations, we are proposing a 2009
implementation date for low permeation fuel hose for small businesses producing Small SI non-
handheld equipment.
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10.7.4 Hardship Provisions—Regulatory Flexibility Options for Engine, Equipment,
Vessel, and Fuel System Component Manufacturers
The Panel recommended that EPA propose two hardship programs for manufacturers.
EPA has adopted similar hardship provisions in a number of previous rules. The following
section summarizes the hardship provisions recommended by the Panel which would be
available to engine manufacturers, equipment manufacturers, vessel manufacturers, and fuel
system component manufacturers (i.e., fuel tank, fuel hose, and fuel cap manufacturers).
10.7.4.1 SBAR Panel Recommendations
Unusual Circumstances Hardship - The Panel recommended that EPA propose a
provision allowing for hardship relief under unusual circumstances for manufacturers affected by
this rule. Manufacturers would be able to apply for hardship relief if circumstances outside their
control cause the failure to comply and if failure to sell the subject engines or equipment would
jeopardize the company's solvency. An example of an unusual circumstance outside a
manufacturer's control may be an "Act of God," a fire at the manufacturing plant, or the
unforeseen shut down of a supplier with no alternative available.
Economic Hardship - The Panel recommended that EPA propose economic hardship
provisions for small businesses affected by this rule. Small manufacturers would be able to
petition EPA for limited additional lead time to comply with the standards. A manufacturer
would have to make the case that it has taken all possible business, technical, and economic steps
to comply, but the burden of compliance costs would have a significant impact on the company's
solvency.
10.7.4.2 EPA's Proposed Hardship Provisions
We have chosen to propose the Panel's recommended regulatory flexibility provisions.
The following is a discussion of the proposed provisions.
Unusual Circumstances Hardship - Under the proposed unusual circumstances hardship
provision, manufacturers would be able to apply for hardship relief if circumstances outside their
control cause the failure to comply and if failure to sell the subject engines or equipment would
jeopardize the company's solvency (see §1068.245). The terms and time frame of the relief
would depend on the specific circumstances of the company and the situation involved. As part
of its application for hardship, a company would be required to provide a compliance plan
detailing when and how it would achieve compliance with the standards. This hardship
provision would be available to all business engine manufacturers, equipment manufacturers,
vessel manufacturers, and fuel system component manufacturers, regardless of size.
Economic Hardship - Under the proposed economic hardship provision, small business
manufacturers would be able to petition EPA for limited additional lead time to comply with the
standards (see §1068.250). A manufacturer would have to make the case that it has taken all
possible business, technical, and economic steps to comply, but the burden of compliance costs
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would have a significant impact on the company's solvency. Hardship relief could include
requirements for interim emission reductions and/or purchase and use of emission credits. The
length of the hardship relief would be established during the initial review and would likely need
to be reviewed annually thereafter. As part of its application for hardship, a company would be
required to provide a compliance plan detailing when and how it would achieve compliance with
the standards. This hardship provision would be available only to engine manufacturers,
equipment manufacturers, vessel manufacturers, and fuel system component manufacturers that
are small businesses.
10.8 Projected Economic Effects of the Proposed Rulemaking
The following section summarizes the economic impact on small businesses of the
proposed exhaust and evaporative emission standards for both Small SI engines and equipment
and Marine SI engines and vessels. As noted earlier, the types of companies that will be affected
by the proposed Marine SI standards include OB/PWC engine manufacturers, SD/I engine
manufacturers, boat builders, and marine fuel system component manufacturers (e.g., fuel tank
and fuel hose manufacturers). Similarly, the types of companies that will be affected by the
Small SI standards include nonhandheld engine manufacturers, equipment manufacturers, and
Small SI fuel system component manufacturers (e.g., fuel tank and fuel hose manufacturers).
For the purposes of this analysis, it is assumed that engine manufacturers will bear the cost of
complying with the exhaust emission standards, whereas equipment manufacturers and vessel
manufacturers will bear the cost of complying with the evaporative emission standards.
To gauge the impact of the proposed standards on small businesses, EPA employed a
cost-to-sales ratio test to estimate the number of small businesses that would be impacted by less
than one percent, between one and three percent, and above three percent. The costs used in this
analysis are based on the cost estimates developed in Chapter 6 of this Draft RIA. A description
of the inputs used for each affected industry sector and the methodology used to develop the
estimated impact on small businesses in each industry sector is presented in the docket for this
rulemaking.2
For OB/PWC engine manufacturers, EPA identified one small business. The one small
business identified by EPA manufactures their personal watercraft today using four-stroke
engines with certified emission levels below the proposed standards. As a result, the estimated
costs for upgrading their engines would not apply. We therefore believe the impact of the rule is
well below one percent of revenues for this OB/PWC engine manufacturer.
For <373 kW SD/I engine manufacturers, EPA identified nine small businesses. Of these
companies, eight produce conventional SD/I engines and the remaining one company produces
SD/I engines for airboats. Of the conventional SD/I small business engine manufacturers, five of
the small businesses may incur compliance costs between one and three percent of their annual
revenues. Three of the small businesses that produce <373 kW SD/I engines as part of a much
broader line of work (such as engine rebuilding or selling land-based engines) will be impacted
by less than one percent of annual revenues.
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Small-Business Flexibility Analysis
Using available information for the airboat engine manufacturer, we project that the
manufacturer will have compliance costs between one and three percent of annual revenues.
Some of this company's engines are >373 kW, so their estimated compliance burden reflects a
combination of costs for conventional SD/I engines and for high-performance >373 kW engines.
(They are included in the conventional SD/I category for this impact analysis.) This company is
unique in that it manufacturers many of its engines for sale to other airboat manufacturers,
resulting in a concentrated cost impact relative to their revenues.
We also identified a number of other airboat manufacturers. These small businesses
making engines for airboats are less reliant on selling engines to other boat builders, instead
making engines for the boats they build themselves. Most of these businesses are very small,
with little ability to marshal the technical resources needed to comply with emission standards.
If these companies would take on the effort to design and certify compliant engines, they would
likely experience compliance costs exceeding three percent of their revenues. However, given
their place in the market and the fact that they are primarily boat builders with the
resourcefulness to make their own engines, we believe the most likely approach for these
companies is to buy a certified engine from manufacturers of conventional SD/I engines. As
such, these companies would be treated with other boat builders, in which case their main
compliance cost is related to evaporative emissions (as described below). We therefore do not
consider any of these companies as engine manufacturers for the purposes of analyzing the
impact of the proposed standards on engine manufacturers.
For >373 kW SD/I engine manufacturers, EPA identified 19 small businesses. Of the
>373 kW SD/I small business engine manufacturers, 17 of the small businesses are projected to
incur compliance costs between one and three percent of their annual revenues. Two small
businesses that produce >373 kW SD/I engines as part of a broader line of work (such as engine
testing) will be impacted by less than one percent of annual revenues.
For boat builders, EPA believes there are over 1,000 small business manufacturers.
Many of these companies make small numbers of vessels for certain segments of the marine
market. Given the high cost of most boats, EPA believes the cost impact will be below one
percent for all small business boat builders, including those that manufacture SD/I vessels, and
OB/PWC boat manufacturers as well.
While boat builders have the primary responsibility under the proposed regulations for
complying with evaporative emission standards, fuel hose and fuel tank manufacturers will have
to certify their product with EPA. EPA has identified one small business that manufactures fuel
hose for marine applications and 15 small businesses that manufacturer fuel tanks for marine
applications. The company producing fuel hose primarily distributes hoses made by other
manufacturers but does produce its own fill neck hose. Because we expect vessel manufacturers
will design their fuel systems such that there will not be standing liquid fuel in the fill neck (and
therefore the proposed low permeation fuel hose requirements will not apply to the fill neck), we
have not included this manufacturer in our analysis. Of the 15 fuel tank manufacturers, EPA has
estimated that all of them will incur costs below one percent of annual revenues.
10-21
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Draft Regulatory Impact Analysis
For Small SI engine and equipment manufacturers, EPA has identified 370 small
businesses.3 Ten of the small businesses are engine manufacturers and the remaining companies
are equipment manufacturers. Based on an analysis of sales revenues by company, EPA projects
that 314 of the small businesses are estimated to incur compliance costs representing less than 1
percent of their annual revenues. EPA projects that 38 companies will incur compliance costs
between 1 and 3 percent of their annual revenues, and 18 companies will incur compliance costs
representing more than 3 percent of their annual revenues.
Similar to the requirements noted above for boat manufacturers under the Marine SI
evaporative emission regulations, equipment manufacturers will have the primary responsibility
under the regulations for complying with the Small SI evaporative emission standards.
However, fuel hose and fuel tank manufacturers will have to certify their product with EPA.
EPA has identified two small businesses that manufactures fuel hose for Small SI applications
and 25 small businesses that manufacturer fuel tanks for Small SI applications. Of these
companies, EPA has estimated that all of these companies will incur costs below one percent of
annual revenues.
Table 10.8-1 summarizes the impacts of the proposed regulations on small businesses
impacted by the proposed exhaust and evaporative emission standards for Small SI engines and
equipment and Marine SI engines and vessels.
Table 10.8-1: Summary of Impacts on Small Businesses
Market Sector
Manufacturers of Marine OB/PWC engines
Manufacturers of Marine SD/I engines < 373 kW
Manufacturers of Marine SD/I engines > 373 kW
(high-performance)
Boat Builders
Manufacturers of Fuel Hose and Fuel Tanks for
Marine SI Vessels
Small SI engines and equipment
Manufacturers of Fuel Hose and Fuel Tanks for
Small SI Applications
Total
0-1 percent
1
4
2
>1,000
15
314
27
363
+ >1,000
boat builders
1 -3
percent
0
5
17
0
0
38
0
60
> 3 percent
0
0
0
0
0
18
0
18
10-22
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Small-Business Flexibility Analysis
For a complete discussion of the economic impacts of the proposed rulemaking, see
Chapter 9, the Economic Impact Analysis chapter, of this Draft Regulatory Impact Analysis.
10-23
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Draft Regulatory Impact Analysis
Chapter 10 References
1. Final Panel Report of the Small Business Advocacy Review Panel on EPA's Planned Proposed Rule—Control of
Emissions from Nonroad Spark-Ignition Engines and Equipment, October 17, 2006. (A copy has been placed in
docket EPA-HQ-OAR-2004-0008.)
2. "Small Business Impact Memo, Control of Emissions from Nonroad Spark-Ignition Engines and Equipment,"
EPA memorandum from Phil Carlson to the EPA Docket, March 6, 2007. (Docket Identification EPA-HQ-OAR-
2004-0008-0547.)
3. "Small Entity Analysis of Small Spark Ignition Nonroad Engine and Equipment Manufacturers," memorandum
from Alex Rogozhin and Brooks Depro, RTI Interational, to Phil Carlson, U.S. EPA, December 15, 2006. (Docket
Identification EPA-HQ-OAR-2004-0008-0541.)
10-24
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Regulatory Alternatives
CHAPTER 11: Regulatory Alternatives
Our proposed program represents a blend of exhaust and evaporative emission standards
for small nonroad spark-ignition (SI) engines used in land-based or auxiliary marine
applications, and also recreational Marine SI engines. We believe that the combination of
emission standards and their associated timing are superior to the alternative program options we
considered given their feasibility, cost, and environmental impact. In this chapter we present and
discuss the options that we evaluated in order to make this determination.
Section 11.1 presents each element of our proposed requirements and discusses a variety
of specific alternatives that are either less and more stringent. After this initial assessment,
options that merit a more rigorous examination are identified for analysis in subsequent sections.
Section 11.2 describes the cost of the selected options for each affected engine or system.
Section 11.3 presents the emissions inventory impacts associated with each option. Section 11.4
describes the cost effectiveness ($/ton of emission reduced) of the selected options. Finally, we
present our assessment of the rationale, feasibility, and issues associated with each alternative in
Section 11.5.
The costs, emission reductions, and cost effectiveness of the options analyzed in Sections
11.2 through 11.5 are incremental to the base case (i.e., current requirements) ignoring this
proposal, unless otherwise specified. For example, the more stringent recreational marine
exhaust standards for OB/PWC are evaluated as follow-on requirements to the proposed
requirements and would begin in a later year. Therefore, the analysis for that option reflects only
the more stringent subsequent standards.
For the more stringent options, it is important to note that the analyses depend on data
supporting them. Generally, a scenario was picked for analysis because there was evidence to
suggest that controls such as those identified in the write-ups could be technically feasible at
some point in the future. However, there is some uncertainty with regard to the technical
feasibility of implementing the standards or requirements across all products, the level of the
potential standards selected for analysis (if applicable), the timing for potential introduction, and
the costs of control. However, while these standards were ultimately not selected as the basis for
this proposal, it appears that in some cases they could form the basis for potential future
rulemaking actions.
11.1 Identification of Alternative Program Options
This section provides our description of potential options for each element of our
proposal. Options that do not merit further consideration are eliminated and those that warrant
additional analysis in subsequent sections are identified.
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Draft Regulatory Impact Analysis
11.1.1 Alternative Exhaust Emission Requirements
11.1.1.1 Small SI Engine HC + NOx Standards
11.1.1.1.1 Class I
We considered, but rejected, proposing a less stringent HC + NOx emission standard for
Class I spark-ignition engines. The proposed standard of 10 g/kW-hr is readily achievable with
reasonably priced emission control technology. Furthermore, the lead time for implementing the
proposed standard in 2012 is adequate for applying the catalyst-based technology that will be
used on many of these engines. A less stringent emission standard would not be consistent with
the requirements of section 213 of the Clean Air Act.
A more stringent standard was also considered. Under this option an 8 g/kW-hr HC +
NOx standard would be implemented. For purposes of this analysis we elected to begin the
requirement in the 2015 model year. Due to the technical design relationship between the engine
and running loss control requirement we modeled running loss controls to start in 2015 as well.
This standard represents about a 50 reduction from the existing Phase 2 standard, rather than the
approximately 38 percent reduction associated with the proposal. As analyzed this option also
provides 3 more years of lead time. We believe that manufacturers of side-valve (SV) engines
would choose to convert these families to overhead-valve (OHV) designs. The emissions from
OHV engine are typically lower and deteriorate less than SV engines and thereby result in the
need for only a slightly more active catalyst and improved cooling relative to the technology
changes needed for the proposal. Cooling for the slightly more active OHV catalyst would be
supplied by the engine improvements included in the proposal, such as include optimized head
design for cooling and fan design for cooling air generation. The slightly more active catalyst
can be achieved with either a larger volume and/or a more active mix of precious metals in the
catalyst substrate. It may be possible for SV engines to meet the more stringent emission
standards using catalysts. For SV engines the catalysts would likely need to be larger and more
active. This would result in higher costs and greater catalyst heat generation which may or may
not be able to be handled by the engine's cooling system.
11.1.1.1.2 Class II
For Class II spark-ignition engines, we considered an alternative program option that was
less stringent than the proposal. However, for the same reasons previously stated for Class I
engines, we rejected this alternative from further consideration; the proposal is readily
achievable at a reasonable cost within the lead time provided. A less stringent standard, such as
one at a level not depending on catalyst technology, would not have been consistent with section
213 of the Clean Air Act.
An alternative for a more stringent exhaust HC + NOx emission standard would be 4.0
g/kW-hr along with a delay in the corresponding running loss requirement such that engine
changes are made at one time. For analytical purposes we started this requirement in 2015, four
years beyond that for the proposed standard. Such an exhaust emission standard represents a 67
11-2
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Regulatory Alternatives
percent reduction relative to the existing Phase 2 standard, rather than the 34 percent reduction
associated with the proposal. It also provides four more years of lead time; a phase-in could be
needed since implementation would require the equipment manufacturers involvement for non-
integrated products. In order to achieve the 4.0 g/kW-hr HC + NOx emission standard, we
expect manufacturers would need to make widespread use of closed loop control EFI and three-
way catalysts. The EFI systems would keep engine air-to-fuel mixture closer to stoichiometry
and provide an optimum environment for the maximum reduction in HC+NOx by a three way
catalyst. Changes to the catalyst would likely involve a more active mix of precious metals in
the catalyst substrate. In addition, engine upgrades would be required in some of the Class II
engines commonly used in residential lawn care equipment.
11.1.1.2 Marine Auxiliary Engine CO Standard
The proposed standards for marine auxiliary engines include a CO standard that would
require the use of highly efficient catalytic control. This proposed standard would require the
use of technology to meet emission levels demanded by the market. Manufacturers of gasoline
marine generators are equipping their engines with catalysts for the primary purpose of reducing
ambient CO concentrations around boats. Therefore, we do not believe that it would be useful to
consider a less stringent standard which could enable market penetration of new engine offerings
which potentially endanger public health. At the same time, the standard we are proposing is
very stringent and manufacturers are already designing for reductions which are more than 95
percent below the current CO emission standard. A more stringent standard would do little more
to push technology. Thus, we do not believe that it would be useful to analyze a more stringent
standard.
11.1.1.3 Outboard/Personal Watercraft (OB/PWC) Engine HC + NOx and CO
Emission Standards
The proposed standards for OB/PWC are based on technology that manufacturers are
already certifying and selling nationwide. To meet the proposed requirements, manufacturers
would continue to sell this technology and discontinue their sale of high-emitting old technology
carbureted two-stroke engines. Because the proposed standards can be met with existing
technology, we do not believe that there is an alternative between the proposed standards and the
current standards which would be consistent with the CAA section 213 requirement. Therefore,
we did not analyze a less stringent alternative.
For a more stringent alternative, we considered a set of follow-on standards to those
proposed. We analyzed these as beginning in 2012. For OB/PWC engines greater than 40 kW
these would be at a level of 10 g/kW-hr. For engines less than 40 kW, we adjusted the proposed
standard equation to 28 - 0.45 x rated power(kW) to maintain a continuous curve function. This
alternative also considered a lower CO standard of 200 g/kW-hr for engines greater than 40 kW
with an adjusted standard of 500 - 7.5 x rated power(kW) for engines less than 40 kW to
maintain a continuous standard function. Such standards would be consistent with currently
certified emission levels from some four-stroke outboard engines. Although many four-stroke
engines may be able to meet a 10 g/kW-hr standard with improved engine calibration, it is not
11-3
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Draft Regulatory Impact Analysis
clear that all engines could meet this standard without applying yet unproven catalyst technology
in this application. To model this scenario, we evaluated the costs and emission reductions that
could be achieved through the combined use of calibrated four-stroke engines and four-stroke
engines with catalytic control. This analysis applied catalytic control to larger OB/PWC
engines, which already use or are expected to use electronic fuel injection.
11.1.1.4 Sterndrive/Inboard (SD/I) Engine HC + NOx and CO Standards
For the purposes of this analysis, we subdivided the SD/I category into traditional and
high-performance engine categories. Based on our proposed definitions, high-performance
engines have a rated power greater than or equal to 373 kW (500 hp).
11.1.1.4.1 SD/K373kW
In developing regulatory alternatives for SD/I engines, we considered both what was
achievable without catalysts and what could be achievable with larger, more efficient catalysts
than those we evaluated in our test programs.
With regard to a less stringent option, we considered non-catalyst based standards to be
implemented in the 2009 model year. Chapter 4 presents data on SD/I engines equipped with
exhaust gas recirculation (EGR). HC+NOx emission levels below 10 g/kW-hr were achieved for
each of the engines. CO emissions ranged from 25 to 185 g/kW-hr. For this less stringent
alternative, we consider standards of 10 g/kW-hr HC+NOx and 150 g/kW-hr CO. The current
California HC+NOx standard for these engines is 160 g/kW-hr.
For a more stringent option, we considered more stringent catalyst-based standards than
we are proposing. Many of the SD/I marine engines with catalysts described in Chapter 4 had
HC+NOx emission rates in the 3-4 g/kW-hr range, even with deteriorated catalysts. In the
development testing for this proposed rulemaking, we did not investigate larger catalysts for
SD/I applications. The goal of the development testing was to demonstrate catalysts that would
work within the packaging constraints associated with water jacketing the exhaust and fitting the
engines into engine compartments on boats. However, we did perform testing on engines
equipped with both catalysts and EGR. These engines showed emission results in the 2-3
g/kW-hr range. We expect that these same reductions could be achieved more simply through
the use of larger catalysts or catalysts with higher precious metal loading. As a more stringent
regulatory alternative, we considered a standard of 2.5 g/kW-hr HC+NOx, with no change in the
proposed CO standard, based on the use of larger catalysts. To account for additional
development work that would need to be performed by manufacturers to achieve a lower
standard than the existing California standard, we consider a later implementation date of 2012
for this more stringent alternative with no standard before that time.
11.1.1.4.2 SD/I >373kW
For high-performance SD/I marine engines, we considered a less stringent alternative
11-4
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Regulatory Alternatives
based on engine fuel system upgrades, calibration, or other minor changes such as an air
injection pump rather than catalytic control. These less stringent standards were modeled for the
2009 model year. Manufacturers expressed concern that catalysts may not be practical for these
engines due to the high exhaust flow rates, high emission rates, and low useful life period
between rebuild. For analytical purposes, we selected an alternative standard of 22 g/kW-hr
HC+NOx and 350 g/kW-hr CO, but lower levels in the range of 15-20g/kW-hr HC+NOx and
300g/kW-hr CO may be achievable with the engine modifications identified above. For these
engines, we did not consider a more stringent alternative.
11.1.2 Alternative Evaporative Emission Requirements
11.1.2.1 Small SI Engines
For Small SI engines, we are proposing both permeation and venting emission standards.
The proposed permeation standards are for fuel tanks and fuel lines. We believe that the
proposed standards are reflective of available technology and represent a step change in
emissions performance. Venting emissions include diurnal breathing losses, diffusion, and
running loss emissions. For non-handheld Small SI engines (i.e., Classes I and II), we are
proposing standards for running loss and diffusion emissions, but not for diurnal emissions. We
are not proposing any type of venting emissions control for handheld equipment.
For a less stringent alternative, we considered not requiring venting emission control
(running loss and diffusion emissions) for non-handheld Small SI engines. These requirements
would be deleted from the proposal and thus modeled as being deleted in the years otherwise
required in the proposal.
For a more stringent alternative, we considered applying running loss and diurnal
standards to handheld equipment and setting a diurnal standard for non-handheld (Classes I and
II). In these alternatives, we consider an implementation date of 2012 for handheld and Class I
equipment, and a date of 2011 for Class II equipment.
11.1.2.2 Marine
Similar to the analysis described above for Small SI equipment, we base the less stringent
and more stringent regulatory alternatives on changes in the proposed venting emission
standards. For marine vessels, we proposed diurnal emission standards for all vessel types. For
portable fuel tanks and PWC fuel tanks, the anticipated technology of a sealed system with
pressure relief is fairly straightforward and commonly used today. However, we anticipate that
the proposed diurnal emissions standards for vessels with installed fuel tanks would be based on
the use of passively purged carbon canisters. For a less stringent alternative, we consider not
setting a diurnal emission standard for marine vessels in 2010.1 For a more stringent scenario,
'Note that PWC already meet the proposed standard and would not be affected differently for the
less stringent standard. PWC use sealed systems with pressure relief to prevent fuel spillage during
operation.
11-5
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Draft Regulatory Impact Analysis
we consider a diurnal requirement wherein boat builders would be required to employ active
purge of carbon canister with installed tanks. This means that, when the engine is operating, it
would draw air through the canister to purge the stored hydrocarbons. These purged gasoline
vapors would be used in the engine as fuel.
11.1.3 Summary of Alternative Standards
Table 11.1-1 and Table 11.1-2 show the alternative program options that were selected
above for further consideration.
Table 11.1-1: Exhaust Alternative Program Options for Quantitative Analysis
Source
Exhaust
Alt
1
2
3
4
5
6
Target
Class I
Class II
OB/PWC
SD/I
<373 kW
SD/I
>373kW
Proposal
• lOg/kW-hrHC+NOx
•Begins 20 12
•8g/kW-hrHC+NOx
•Begins 20 11
<40kW
• Decreases with power
output (P)
• HC+NOx g/kW-hr
equation is 28-0. 3P
• CO g/kW-hr equation
is 500-5P
>40kW
• 16 g/kW-hr HC+NOx
• 300 g/kW-hr CO
•Both begin 2009
• 5 g/kW-hr HC+NOx
• 75 g/kW-hr CO
• Begins 2009a
• 5 g/kW-hr HC+NOx
• 350 g/kW-hr CO
• Begins 2009a
less/
more
more
more
more
less
more
less
Alternative Description
• 8 g/kW-hr HC+NOx
• Begins 2015 in lieu of proposed
•3.5g/kW-hrHC+NOx
• Begins 2015 in lieu of proposed
<40kW
• power output (P)
• HC+NOx g/kW-hr equation is 28-0.45P
• COg/kW-hr equation is 500-7. 5P
>40kW
• 10 g/kW-hr HC+NOx
• 200 g/kW-hr CO
•Both begin 2012 in addition to 2009
standards
• 10 g/kW-hr HC+NOx
• 150 g/kW-hr CO
• Same effective dates as proposal
• 2.5 g/kW-hr HC+NOx
• 75 g/kW-hr CO
• Begins 2012 in lieu of proposed standards3
• 22 g/kW-hr HC+NOx
• 350 g/kW-hr CO
• Begins 2009
a Does not include small business flexibilities that will delay the effective date of the requirements for some
companies.
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Regulatory Alternatives
Table 11.1-2: Evaporative Alternative Program Options for Quantitative Analysis
1 Source
Alt
Target
Proposal
less/
more
Alternative Description 1
Evap
7
8
9
10
11
12
HH
diurnal/
running
loss
Class I
& Class
II
diffusion
&
running
loss
Class I
& Class
II diurnal
Installed
marine
fuel tank
diurnal
Portable
marine
fuel tank
diurnal
• None
• 0.8 g/day HC
diffusion standard
• Running loss is a
"zero emission" design
standard
•Class I begins 20 12
and Class II begins
2011
• None
• 0.4g/gal/day HC
trailerable boat
•0.16g/gal/dayHC
non-trailerable boat
•Begins 20 10
• Diurnal is a "zero
emission" design
standard
• Begins 20 12
more
less
more
less
more
less
•Begins 20 12
• No running loss and no diffusion
• Requirement would begin in 2012 for Class
I and 20 11 for Class II
•No diurnal for 20 10
• More stringent test procedure. If charcoal
canister is used, active purge required.
•Would begin 20 10
• No diurnal
11.2 Cost per Engine
This section describes the estimated cost of complying with the alternative program
options. We developed the costs for individual technologies using estimates from ICF
Incorporated,1'2'3 conversations with manufacturers, other information including the published
literature, and our best technical judgment. Also, the cost estimates for the alternatives rely
heavily on the methodology and in some cases the actual cost data, used to characterize the
proposed standards. For ease of presentation, we have not repeated the methodology or those
detailed cost data here. Instead, we focus on presenting information regarding the requirements
or changes that we expect will be needed to comply with the alternative options. The reader is
encouraged to refer to Chapter 6 for more information. Finally, we did not specifically analyze
the incremental costs of setting standards which would not result in technology which would
allow certification in all 50 states (a harmonized program).
The costs of complying with the alternative program options are presented as
incremental to the base case (current requirements) without considering the proposal. The only
exception to this is the second phase of OB/PWC standards where costs are incremental to the
proposal. The alternatives and the requisite technology are described in Section 11.1. Further,
results are provided as the average cost per affected engine and the total net present value
11-7
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Draft Regulatory Impact Analysis
(NPV) for a 30-year period beginning in 2008. The NPV estimates are based on a seven percent
discount rate. All costs are in 2005 dollars.
11.2.1 Costs for Exhaust Emission Standards
11.2.1.1 More Stringent Small SI Engine HC + NOx Standards
11.2.1.1.1 Class I
Meeting more stringent standards would require OHV engines to use a slightly larger or
more active catalyst than for the proposed standards. For current SV engines they would need
to utilize larger and more active catalysts than considered in the analysis for the proposed
standards, or convert to OHV design and use a slightly larger catalyst or more active catalyst
than for the proposed standards.
The cost for the SV sized catalyst is outlined in Chapter 6. The cost for the conversion
from SV to OHV design is drawn from ICF International's 2006 report "Small SI Engine
Technologies and Costs4," and is listed as $9.42 in variable costs per engine, $2,010,147 in
tooling changes and design and development, as well as $15 million in facility upgrades per
Class I SV engine family. The 2005 EPA certification database lists five SV engine families
certified to Phase 2 of which two engines have OHV engine designs in the same power range
and one engine family is listed as a small volume engine family. The remaining two engine
families have sales estimates in the millions of engines. As a result, fixed costs are applied two
engine families and variable costs are applied to all SV engines.
The cost for improvements in OHV current engine designs includes improved cylinder
head design for improved engine cooling, redesign of the engine flywheel to provide optimum
cooling for the catalyst muffler as well as carburetor improvements. Research and development
and tooling for these changes are estimated at $456,450 per engine family as shown in Chapter
6.
Upgrades in catalysts for OHV engines include additional precious metal for more
active catalysts. The catalyst estimates for the SV engine families, that are replaced by OHV
engine families, are also replaced with the OHV catalyst costs. These costs for improved OHV
engines, upgraded catalysts for OHV engines are included in Table 11.2-1 together with those
for SV engines.
11.2.1.1.2 ClassII
Technologies for the more stringent option include improved engine design (redesign of
cooling fins, fan design, combustion chamber design), closed loop control electronic fuel
injection (EFI), catalysts and pressurized oil lube system for engines intended for residential
use. The fixed costs for improved engine design are $456,000 per engine family and include
R&D and tooling costs, as listed in Chapter 6. The same Chapter lists EFI variable costs at $79
per engine when it includes the credit for the removal of the carburetor. The fixed costs for
11-8
-------
Regulatory Alternatives
closed loop fuel injection design is estimated at $103,000 per engine family. Increased catalyst
efficiency is achieved through use of a larger catalyst and increased precious metal loading at
an estimated increased catalyst cost of $4 (1000 hr engine) - $16 (250 hr engine) per engine. A
pressurized lube oil system is listed by ICF5 to be $15.48 in variable costs and $210,000 in fixed
costs per engine family for the residential engines which often do not use it in today's design.
Overall, fuel savings would be increased due to the application of electronic fuel injection to all
Class II engines.
Table 11.2-1: Small SI Per-Engine Cost Estimates (Without Fuel Savings)
Sales Weighted Averages
Short Term (years 1-5)
Long Term (years 6-10)
Proposed
Class I
Class II
$ll-$23
$39-$86
$9-$15
$27-$45
More Stringent
Class I
Class II
$18-$23
$121-$153
$16-$17
$79-$97
11.2.1.2 Outboard/Personal Watercraft (OB/PWC) Engine HC + NOx and CO
Emission Standards
We believe that, to meet the more stringent alternative considered here, manufacturers
would need to convert their product lines primarily to a mix of calibrated four-stroke engines
and engines equipped with catalysts. To model this approach, we looked at a technology mix
that would achieve the 10 g/kW-hr HC+NOx limit, with appropriate considerations given to
emissions deterioration rates and compliance margins. This technology mix was developed by
assuming that all carbureted two-stroke engines would be removed from the fleet and replaced
with four-stroke engines. All engines over 75 kW (100 hp) were modeled as using catalytic
control. Detailed costs for converting engines from two-stroke to four-stroke and for equipping
OB/PWC engines with catalysts are presented in Chapter 6. Table 11.2-2 compares the average
per-engine equipment costs for the primary and the more stringent alternatives for OB/PWC
engines.
11-9
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Draft Regulatory Impact Analysis
Table 11.2-2: OB/PWC Per-Engine Cost Estimates (Without Fuel Savings)
Sales Weighted Averages
Proposed
More Stringent
Incremental Cost3
OB
PWC
OB
PWC
OB
PWC
Short Term (years 1-5)
$284
$359
$369
$518
$85
$159
Long Term (years 6-10)
$219
$272
$256
$389
$37
$117
a Incremental cost is presented here because the more stringent alternative for OB/PWC
includes the primary standard in 2009 plus a second, more stringent, standard in 2012.
We did not model differences in fuel savings between the primary and more stringent
alternatives. The fuel savings for all three alternatives primarily come from the replacement of
carbureted two-stroke engines with cleaner engine designs. In both the primary and more
stringent scenarios, we model the discontinuation of sales of carbureted two-stroke engines.
11.2.1.3 Sterndrive/Inboard (SD/I) Engine HC + NOx and CO Emission Standards
With regard to the less stringent alternative, Chapter 4 presents costs for using exhaust
gas recirculation (EGR) on SD/I engines. To estimate the costs for the less stringent alternative,
all SD/I engines less than 373 kW were modeled to be equipped with electronic closed loop
control fuel injection and EGR.
Engines greater than 373 kW were modeled to meet the less stringent alternative
standard through engine calibration and increased use of electronic fuel injection (from 50
percent use to 75 percent use). This increased fuel injection use is intended to account for some
carbureted engines that would not be able to meet the standard while acknowledging the data in
Chapter 4 suggesting that some carbureted engines would be able to meet this alternative
standard, using calibration changes or other engine modifications.
For the more stringent case, we consider a larger catalyst size with a higher precious
metal loading for engines less than 373 kW and no change from the primary catalyst alternative
for engines greater than 373 kW. Specifically, for engines less than 373 kW, we model a 25
percent larger catalyst and an additional 25 percent precious metal loading. We do not model a
difference in fuel consumption for any of the three scenarios because, in each case, all engines
are anticipated to use electronic fuel injection. To reiterate, we did not include a more stringent
standard for high performance SD/I engines. Table 11.2-3 compares the per-engine cost
estimates for the primary, less stringent, and more stringent alternatives.
11-10
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Regulatory Alternatives
Table 11.2-3: SD/I Per-Engine Cost Estimates (Without Fuel Savings)
Sales Weighted Averages
Proposed <373 kW
>373 kW
Less Stringent <373
kW
>373 kW
More Stringent <373 kW
>373 kW
Short Term (years 1-5)
$360
$920
$216
$284
$435
$920a
Long Term (years 6-10)
$272
$672
$160
$155
$337
$672a
a There is no more stringent option for these engines. Costs shown are for the proposal and are
used later to develop aggregate values for the combination of more stringent marine options
later in this section.
11-11
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Draft Regulatory Impact Analysis
11.2.2 Costs for Evaporative Emission Standards
11.2.2.1 Small SI Engine
For the less stringent case, we simply subtract the costs of running loss and diffusion
controls for non-handheld equipment. For the more stringent case, we add the incremental costs
of diurnal emission control for all nonhandheld engines and diurnal emission control, diffusion
control, and running losses for handheld engines. These technology costs are presented in
Chapter 6. Table 11.2-4 compares the per-equipment cost estimates for the primary, less
stringent, and more stringent alternatives.
Table 11.2-4: Evaporative Small SI Per-Equipment Cost Estimates (Without Fuel Savings)
Sales Weighted Averages
Proposed Aggregate
Handheld
Class I
Class II
Less Stringent
Aggregate
Handheld
Class I
Class II
More Stringent Aggregate
Handheld
Class I
Class II
Short Term (years 1-5)
$3.36
$0.82a
$3.16
$6.90
$1.82
$0.82a
$1.11
$4.40
$7.24
$4.40
$6.12
$11.25
Long Term (years 6-10)
$2.54
$0.69a
$2.29
$5.30
$1.31
$0.69a
$0.65
$3.30
$5.64
$3.55
$4.66
$8.78
a Values reflect the proposed permeation standards. These costs are used in the alternative
analysis only to develop aggregate values for comparison purposes.
11-12
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Regulatory Alternatives
Table 11.2-5 presents the fuel savings for the three alternatives, based on the
evaporative emission reductions for each of the scenarios. Because evaporative emissions are
basically gasoline vapor lost to the atmosphere, these hydrocarbon reductions can be directly
translated to gasoline savings using a gasoline cost of $1.81 per gallon. Cost savings are
presented both with a 3 percent and a 7 percent discount factor over the life of the equipment.
Table 11.2-5: Projected Evaporative Fuel Savings for Small SI Equipment
Sales Weighted Averages
Proposed Aggregate
Handheld
Class I
Class II
Less Stringent
Aggregate
Handheld
Class I
Class II
More Stringent Aggregate
Handheld
Class I
Class II
Lifetime Gallons Saved
1.4
0.2a
0.8
4.7
0.9
0.2a
0.5
3.0
1.5
0.3
0.9
5.3
Discounted Cost Savings
3 percent 7 percent
$2.34
$0.32a
$1.39
$7.24
$1.51
$0.32a
$0.89
$4.60
$2.61
$0.46
$1.50
$8.12
$2.18
$0.31a
$1.32
$5.98
$1.41
$0.31a
$0.85
$3.80
$2.42
$0.46
$1.43
$6.70
a Values reflect the proposed permeation standards. These costs are used in the alternative
analysis only to develop aggregate values for comparison purposes.
11-13
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Draft Regulatory Impact Analysis
11.2.2.2 Marine
For the less stringent case, we simply subtract the costs of diurnal emission controls
from marine vessels with installed and portable fuel tanks. For the more stringent case, we add
the incremental costs of actively purged diurnal emission control for vessels with installed fuel
tanks. These technology costs are presented in Chapter 6. Table 11.2-6 compares the per-
equipment cost estimates for the primary, less stringent, and more stringent alternatives. Cost
savings are presented both with a 3 percent and a 7 percent discount factor over the life of the
vessel.
Table 11.2-6: Per-Vessel Cost Estimates (Without Fuel Savings)
Sales Weighted Averages
Proposed Aggregate
portable
PWC
installed
Less Stringent Aggregate
portable
PWC
installed
More Stringent Aggregate
portable
PWC
installed
Short Term (years 1-5)
$55
$12a
$17a
$74
$33
$11
$17a
$42
$69
$12a
$17a
$94
Long Term (years 6-10)
$36
$8a
$lla
$62
$27
$7
$lla
$36
$56
$8a
$lla
$77
a Values reflect the proposed permeation and diurnal standards. These costs used in the
alternative analysis only to develop aggregate values for comparison purposes.
11-14
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Regulatory Alternatives
Table 11.2-7 presents the fuel savings for the three alternatives. These fuel savings are
based on the evaporative emission reductions for each of the scenarios. Because evaporative
emissions are basically gasoline vapor lost to the atmosphere, preventing these hydrocarbon
emissions can be directly translated to gasoline savings using a gasoline cost of $1.81 per
gallon.
Table 11.2-7: Projected Evaporative Fuel Savings for Marine Vessels
Sales Weighted Averages
Proposed Aggregate
portable
PWC
installed
Less Stringent
Aggregate
portable
PWC
installed
More Stringent Aggregate
portable
PWC
installed
Lifetime Gallons Saved
31
15a
9a
41
22
12
9a
28
32
15a
9a
43
Discounted Cost Savings
3 percent 7 percent
$45
$22
$15
$59
$33
$18
$15
$41
$47
$23
$15
$62
$36
$19a
$13a
$45
$26
$15
$13a
$32
$37
$19a
$13a
$47
a Values reflect the proposed permeation and diurnal standards. These costs used in the
alternative analysis only to develop aggregate values for comparison purposes.
11-15
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Draft Regulatory Impact Analysis
11.2.3 Cost Summary of Regulatory Alternatives
Table 11.2-8 summarizes the average cost per engine for the various alternative program
options described above. The costs presented are for the short term and do not include fuel
savings.
Table 11.2-8: Engine Cost Summary Range for Alternative Program Options ($/Engine)
Sales Weighted Averages of Short-Term Costs without Fuel Savings, 2005$
Source
Exhaust
Evap
Alt
1
2
3a
4
5
6
7b
8
9b
10
11
12
Target
Class I
Class II
OB/PWC
SD/I <373 kW
SD/I >373 kW
HH
Class I & Class II
Class I & Class II
Installed marine fuel
tank
Portable marine fuel tank
Proposal
$ll-$23
$39-$86
$-
$360
$920
$-
$4.41
$-
$74
$12
Scenario
more
more
more
less
more
less
more
less
more
less
more
less
Alternative
$18-$23
$121-$153
$70
$216
$435
$284
$3.58
$2.19
$3.45
$42
$94
$11
a Costs are presented incremental to the proposal for OB/PWC because, for this alternative, a
second stage of standards is considered in 2012 beyond the 2009 proposal.
b Only considers standards for venting emission control which are not in the proposal. The
venting emission standards considered here are diurnal for Class I and Class II and
diurnal/running loss/diffusion for handheld.
Table 11.2-9 summarizes the 30-year net present value for costs for the proposal and the
various alternative program options described in Table 11.2-1. Cost results are provided as the
total net present value (NPV) for a 30-year period. The NPV estimates are based on a 7 percent
discount rate. These costs do not include fuel savings. Table 11.2-10 presents the same
information with a 3 percent discount rate.
11-16
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Regulatory Alternatives
Table 11.2-9: 30-Year Net Present Value Cost Summary for Alternative Small SI
Program Options with a 7 Percent Discount Rate (Million 2005$)
Source
Exhaust
Evap
Alt
1
2
3a
4
5
6
7b
8
9b
10
11
12
Target
Class I
Class II
OB/PWC
SD/I <373 kW
SD/I >373 kW
HH
Class I & Class II
Class I & Class II
Installed marine fuel
tank
Portable marine fuel tank
Proposal
$1225
$2080
$-
$396
$11
$-
$829
$-
$291
$17
Scenario
more
more
more
less
more
less
more
less
more
less
more
less
Alternative
$1499
$4360
$297
$239
$391
$3
$319
$382
$570
$166
$361
$16
a Costs are presented incremental to the proposal for OB/PWC because, for this alternative, a
second stage of standards is considered in 2012 beyond the 2009 proposal.
b Only considers standards for venting emission control which are not in the proposal. The
venting emission standards considered here are diurnal for Class I and Class II and
diurnal/running loss/diffusion for handheld.
Table 11.2-10: 30-Year Net Present Value Cost Summary for Alternative Small SI
Program Options with a 3 Percent Discount Rate (Million 2005$)
Source
Exhaust
Evap
Alt
1
2
3a
4
5
6
7b
8
9b
10
11
12
Target
Class I
Class II
OB/PWC
SD/I <373 kW
SD/I >373 kW
HH
Class I & Class II
Class I & Class II
Installed marine fuel
tank
Portable marine fuel tank
Proposal
$2,105
$3,387
$-
$596
$16
$-
$1,367
$-
$458
$24
Scenario
more
more
more
less
more
less
more
less
more
less
more
less
Alternative
$2,770
$7,910
$465
$359
$638
$4
$544
$617
$963
$265
$567
$22
a Costs are presented incremental to the proposal for OB/PWC because, for this alternative, a
second stage of standards is considered in 2012 beyond the 2009 proposal.
b Only considers standards for venting emission control which are not in the proposal. The
venting emission standards considered here are diurnal for Class I and Class II and
11-17
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Draft Regulatory Impact Analysis
diurnal/running loss/diffusion for handheld.
11.3 Emission Reduction
This section describes the estimated emission reductions associated with each of the
alternative program options. We developed these estimates using the NONROAD emissions
inventory model and methodology described in Chapter 3. The modeling inputs for alternative
options are provided in Appendix 11A and Appendix 1 IB.
The incremental emission reductions of complying with the alternative program options
are presented as incremental to the base case without the proposal. The only exception to this is
the second phase of OB/PWC standards. The alternatives and the requisite technology are
described in Section 11.1. Further, emission inventory results are provided as the total net
present value (NPV) for a 30-year period. The NPV estimates are calculated based on both a 7
percent and a 3 percent discount rate. Small SI and Marine SI emission reductions are
presented separately in Tables 11.3-1 and 11.3-2.
Table 11.3-1: 30-Year Net Present Value
Emission Reduction Summary for Alternative Small SI
Program Options with a 7 Percent Discount Rate (Million Tons)
Source
Exhaust
Evap
Alt
1
2
3a
4
5
6
7b
8
9b
10
11
12
Target
Class I
Class II
OB/PWC
SD/I <373 kW
SD/I >373 kW
HH
Class I & Class II
Class I & Class II
Installed marine fuel
tank
Portable marine fuel tank
Proposal
0.78
1.01
0
0.33
0.004
0
1.02
0
0.40
0.08
Scenario
more
more
more
less
more
less
more
less
more
less
more
less
Alternative
0.67
1.26
0.23
0.21
0.30
0.002
0.04
0.60
0.12
0.28
0.42
0.06
a Tons reduced are presented incremental to the proposal for OB/PWC because, for this
alternative, a second stage of standards is considered in 2012 beyond the 2009 proposal.
b Only considers standards for venting emission control which are not in the proposal. The
venting emission standards considered here are diurnal for Class I and Class II and
diurnal/running loss/diffusion for handheld.
11-18
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Regulatory Alternatives
Table 11.3-2: 30-Year Net Present Value
Emission Reduction Summary for Alternative Small SI
Program Options with a 3 Percent Discount Rate (Million Tons)
Source
Exhaust
Evap
Alt
1
2
3a
4
5
6
7b
8
9b
10
11
12
Target
Class I
Class II
OB/PWC
SD/I <373 kW
SD/I >373 kW
HH
Class I & Class II
Class I & Class II
Installed marine fuel
tank
Portable marine fuel tank
Proposal
1.41
1.82
0
0.61
0.007
0
1.80
0
0.76
0.14
Scenario
more
more
more
less
more
less
more
less
more
less
more
less
Alternative
1.30
2.48
0.44
0.38
0.58
0.003
0.07
1.04
0.21
0.53
0.78
0.12
a Tons reduced are presented incremental to the proposal for OB/PWC because, for this
alternative, a second stage of standards is considered in 2012 beyond the 2009 proposal.
b Only considers standards for venting emission control which are not in the proposal. The
venting emission standards considered here are diurnal for Class I and Class II and
diurnal/running loss/diffusion for handheld.
11-19
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Draft Regulatory Impact Analysis
11.4 Cost Effectiveness
This section describes the cost effectiveness associated with each of the alternative
program options. The costs are expressed as millions of dollars and the emission reductions are
in terms of short tons. All results are presented as incremental to the base case without the
proposal. The only exception to this is the second phase of OB/PWC standards where the
values are calculated based on costs and emission reductions incremental to the proposal.
Tables 11.4-1 and 11.4-2 present cost per ton estimates, using both a 7 percent and a 3 percent
discount rate, for Small SI engines/equipment and Marine SI engines/vessels as outlined in
Table 11.2-1.
Table 11.4-1: Comparison of Cost Effectiveness for Proposal and Alternatives
Without Fuel Savings, 7 Percent Discount Rate ($/ton) 2005$
Source
Exhaust
Evap
Alt
1
2
3a
4
5
6
7b
8
9b
10
11
12
Target
Class I
Class II
OB/PWC
SD/I <373 kW
SD/I >373 kW
HH
Class I & Class II
Class I & Class II
Installed marine fuel
tank
Portable marine fuel tank
Proposal
$1585
$2055
$740
$1200
$2940
NA
$770
NA
$720
$230
Scenario
more
more
more
less
more
less
more
less
more
less
more
less
Alternative
$2240
$3470
$1280
$1160
$1330
$1920
$8150
$640
$4910
$600
$870
$250
a Cost effectiveness of more stringent alternative is presented incremental to the proposal for
OB/PWC because, for this alternative, a second stage of standards is considered in 2012 beyond
the 2009 primary alternative.
b Only considers standards for venting emission control which are not in the proposal. The
venting emission standards considered here are diurnal for Class I and Class II and
diurnal/running loss/diffusion for handheld.
11-20
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Regulatory Alternatives
Table 11.4-2: Comparison of Cost Effectiveness for Proposal and Alternatives
Without Fuel Savings, 3 Percent Discount Rate ($/ton) 2005$
Source
Exhaust
Evap
Alt
1
2
3a
4
5
6
7b
8
9b
10
11
12
Target
Class I
Class II
OB/PWC
SD/I <373 kW
SD/I >373 kW
HH
Class I & Class II
Class I & Class II
Installed marine fuel
tank
Portable marine fuel tank
Proposal
$1,500
$1,860
$630
$980
$2370
NA
$720
NA
$600
$180
Scenario
more
more
more
less
more
less
more
less
more
less
more
less
Alternative
$2,130
$3,180
$1050
$950
$1100
$1440
$8150
$640
$4910
$500
$730
$190
a Cost effectiveness of more stringent alternative is presented incremental to the proposal for
OB/PWC because, for this alternative, a second stage of standards is considered in 2012 beyond
the 2009 primary alternative.
b Only considers standards for venting emission control which are not in the proposal. The
venting emission standards considered here are diurnal for Class I and Class II and
diurnal/running loss/diffusion for handheld.
Ideally, this analysis would include an assessment of the monetized benefits which
would
potentially accompany each alternative as was provided in Chapter 8. This would provide
further information for decision making and comparison to the proposed program.
Unfortunately, the emissions data needed to conduct such an analysis, such as the potential PM
benefits for the more stringent exhaust emission scenarios, is not available for this NPRM. This
limits the utility of any comparisons which could be made since monetized benefits are partially
dependent on PM health benefits.
11.5 Summary and Analysis of Alternative Program Options
This section presents a comparative summary of the important aspects related to the
various alternative program options and our rationale for not pursuing an option relative to the
proposal.
11.5.1 Exhaust Emission Standards
11-21
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Draft Regulatory Impact Analysis
11.5.1.1 Small SI Engine HC + NOx Standards
11.5.1.1.1 Class I
This alternative considers a more stringent standard of 50 percent HC+NOx emission
reduction beginning in 2015 for Phase 3 Class I engines instead of a reduction of 38 percent
beginning in 2012 . While these emission standards may be feasible it is clearly in the in the
longer term relative to the timing of the standards we are proposing. For analytical purposes the
time line to begin implementation of the new standards was set at the 2015 model year. This is
three model years past the implementation year for the proposed standards. For the analytical
period we considered, the proposal provides more emission reductions than the alternative by
211,000 tons between 2012 and 2020. Postponing the exhaust emission standards to 2015 could
likely also lead to postponing controls on running loss emissions with an additional loss of
44,000 tons of control. States with air quality problems would benefit from emission reductions
in an earlier time frame. Thus, while both approaches are cost effective, we elected to go with
the 38 percent reduction in 2012. In the context of section 213(a)(3) of the Clean Air Act, it
represents the most stringent standards feasible within the lead time considered.
11.5.1.1.2 ClassII
This alternative considers a more stringent standard of 4g/kW-hr HC+NOx , a reduction
of about 67 percent for Class II engines over phase 2. These standards assume the use of closed
loop electronic fuel injection and catalysts on all Class II engines. For the current proposal, we
are expecting engine manufacturers to meet the standards by applying closed loop EFI on a
portion of their V-twin engines and for the engine manufacturers or equipment manufacturers to
use catalytic mufflers on the remaining engines. While these emission standards may be
feasible it is clearly in the in the longer term relative to the timing of the standards we are
proposing. For analytical purposes the time line to begin implementation of the new standards
was set at the 2015 model year. This is four model years past the implementation year for the
proposed standards. For the 30 year analytical period we considered, the proposal provides
fewer overall emission reductions than the alternative, but between 2011 and 2020 the proposal
gives 177,000 tons more reduction than the alternative assuming that running loss control is
also postponed to begin in the 2015 model year. States with air quality problems would benefit
from emission reductions in an earlier time frame. Thus, while both approaches are cost
effective, we elected to go with the 34 percent reduction in 2011. In the context of section
213(a)(3) of the Clean Air Act, it represents the most stringent standards feasible within the lead
time considered.
11.5.1.2 Outboard/Personal Watercraft (OB/PWC) Engine HC + NOx and CO
Emission Standards
We analyzed the costs and emission reductions associated with more stringent standards
for OB/PWC engines. We have concerns with proposing this second tier of OB/PWC standards
at this time. While some four-stroke engines may be able to meet a 10 g/kW-hr standard with
improved calibrations, it is not clear that all engines could meet this standard without applying
11-22
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Regulatory Alternatives
catalyst technology. Direct injection two-strokes engines would face additional challenges. At
this time, we believe it is not appropriate to base standards in this rule on the use of catalysts for
OB/PWC engines. Although this technology may be attractive in the longer term, little
development work has been performed on the application of 3-way catalysts to OB/PWC
engines.
For this alternative, our modeling assumes all OB/PWC engines which need to can successfully
apply aftertreatment technology.
11.5.1.3 Sterndrive/Inboard (SD/I) Engine HC + NOx and CO Emission Standards
11.5.1.3.1 SD/K373kW
With regard to less stringent standards, we believe that EGR would be a technologically
feasible and cost-effective approach to reducing emissions from SD/I marine engines.
However, we believe that greater reductions could be achieved through the use of catalysts. We
considered basing an interim standard on EGR, but were concerned that this would divert
manufacturers' resources away from catalyst development and could have the effect of delaying
emission reductions from this sector. Setting a less stringent standard would likely be
inconsistent with the requirements of section 213 of the Clean Air Act because at least one SD/I
engine manufacturer offers a compliant product for sale in the US. In the NPRM we do ask for
comment on a short-phase-in to deal with a change in the engine a supplier's product lines.
With regard to more stringent requirements, we do not believe that they would
necessarily lead to any further significant emission reductions in HC+NOx. Because this is the
first generation of emission standards for this category of recreational marine engines, we
believe that most manufacturers will strive to achieve emission levels below the proposed
standards to give them certainty that they will pass the standards in-use, especially as catalysts
on SD/I engines are a new technology. Therefore, we do not believe that it is necessary at this
time to consider a lower standard for these engines.
11.5.1.3.2 SD/I >373kW
This section addresses the alternative of setting less stringent standards for high
performance SD/I engines. These engines have very high power outputs, large exhaust gas flow
rates, and relatively high concentrations of hydrocarbons and carbon monoxide in the exhaust
gases. From a conceptual perspective, the application of catalytic converter technology to these
engines is feasible. As is the case in similar heavy-duty on-highway gasoline engines, these
catalytic converters would have to be quite large in volume, perhaps on the order of the same
volume as the engine displacement, and would involve significant heat rejection issues.
Manufacturers have expressed concern that catalysts may not be practical for these
engines due to the high exhaust flow rates and short low useful life periods. We are requesting
comment on an alternative approach not based on catalysts but based on engine and fuel system
modifications. This option is less costly and more cost effective than our primary proposal, but
provides less emission reductions. This alternative remains under active consideration. We
11-23
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Draft Regulatory Impact Analysis
intend to continue to work with the marine industry to gather additional data in order to further
investigate this option.
11.5.2 Evaporative Emission Standards
11.5.2.1 Small SI Engine
We analyzed requiring diurnal and running loss control from handheld equipment in
2012. Even though it would be feasible from a strict technical perspective it is not a attractive
option at this time. Fuel tanks from this equipment are very small, most less than one liter, and,
with the exception of commercial equipment, their use is less than 15 hours per year. Adding
hardware to control diurnal and running loss emissions would add weight which could be
problematic on handheld equipment. In addition, it could create the potential for fuel leaks in
equipment which can be used in rotated and inverted positions in the field. In addition, this
option does not appear cost effective. For these reasons we elected not to pursue it.
With regard to controlling running loss and diffusion emissions from non-handheld
equipment we believe it is feasible at a relatively low cost. Running loss emissions can be
controlled by sealing the fuel cap and routing vapors from the fuel tank to the engine intake.
Other approaches would be to move the fuel tank away from heat sources or to use heat
protection such as a shield or directed air flow. Diffusion can be controlled by simply using a
tortuous tank vent path, which is commonly used today on Small SI equipment to prevent fuel
splashing or spilling. These emission control technologies are relatively straight-forward and
inexpensive and do not have the weight and in-use position issues such as mentioned above for
handheld equipment. Deleting the requirement does not meaningfully improve the cost
effectiveness. Not proposing these requirements would be inconsistent with the section 213 of
the Clean Air Act.
California requires control diurnal fuel tank emissions from Class I and Class II
equipment as part of its overall fuel evaporative certification requirements. California requires
an active purge of the control system. We evaluated the alternative of adding a diurnal
requirement like that in California. Even though it would be feasible from a strict technical
perspective it is not a attractive option at this time. While workable, there are some important
issues would need to be resolved for diurnal emission control, such as cost, packaging, and
vibration. Also, California requires an active purge, but we believe that a substantial reduction
on the order of 50 percent could be achieved with a less complicated and less expensive passive
purge approach. Finally, the cost and cost effectiveness of this program sub-element are of
concern given the relatively low emissions levels (on a per-equipment basis) from such small
fuel tanks. Overall, we do not consider this to be an attractive option at this time for Small SI
engines as a group.
11.5.2.2 Marine
Although we considered the alternative of not requiring diurnal emission control for
installed fuel tanks, we believe that carbon canisters are feasible for boats at relatively low cost.
11-24
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Regulatory Alternatives
Carbon canisters have been installed on fourteen boats by industry in a pilot program intended
to demonstrate the feasibility of this technology. The proposed standards would be achievable
through engineering design-based certification with canisters that are much smaller than the fuel
tanks. In addition, sealed systems, with pressure control strategies would be accepted under the
proposed engineering design-based certification. Eliminating these requirements would not
meaningfully affect the cost effectiveness of the marine evaporative program. Not proposing
these controls would be inconsistent with the requirements of section 213 of the Clean Air Act.
We also considered the feasibility of requiring the use of carbon canisters with active
purging to control diurnal emissions. However, we are concerned that active purging would
occur infrequently due to the low hours of operation per year seen by many boats. In addition,
active purge adds complexity into the system in that the engine must be integrated into the
control strategy. This could end up involving engine, tank, and vessel manufacturers in
certification processes. Although we did not model it, this approach would undoubtedly require
more lead time to implement because it is more complex and involves more entities. Based on
data presented in Chapter 5, carbon canisters can be used to reduce emissions by more than 50
percent with passive purging. This passive purging occurs during the normal tank breathing
process caused by ambient temperature changes without creating any significant pressure in the
fuel tank. The small additional benefit of an actively purged diurnal control system would
likely not justify the cost and complexity of implementing such a system, even though it
appears to be cost effective.
Portable marine fuel tanks are used in vessels with outboard motors. Many of these
tanks employ self-sealing vents which close the tank to the atmosphere when it is not in-use.
This is quite straightforward, and it can be applied to all such tanks in the future for a
reasonable cost. Not proposing these controls would be inconsistent with the requirements of
section 213 of the Clean Air Act.
11-25
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Draft Regulatory Impact Analysis
APPENDIX 11 A: Emission Factors for the Less Stringent Alternative
11 A.I Exhaust Emission Factors and Deterioration Rates
11 A. 1.1 Small SI Exhaust
No less stringent exhaust emission standards were quantitatively analyzed for either
Class I or Class II Small SI engines.
11 A. 1.2 Marine SI Exhaust
In the less stringent alternative, the same standards are considered for OB/PWC engines
as for the primary scenario. However, for SD/I engines, we consider less stringent standards.
As discussed above, these standards are based on the use of EGR for SD/I engines less than 373
kW and engine calibration for larger engines. For engines less than 373 kW we considered less
stringent alternative standards of 10 g/kW-hr HC+NOx and 150 g/kW-hr CO for SD/I engines
less than 373 kW. For high-performance engines, we considered a standard of 350 g/kW-hr
HC+NOx. Because these emission factors are based on engine-out emissions, we use the same
deterioration factors (DF) as for the baseline case. Table A-l presents the zero-hour SD/I
emission factors and the accompanying deterioration factors used to model the less stringent
alternative.
Table 11 A-l: Less Stringent Alternative EFs [g/kW-hr] and DFs for SD/I
Engine Category
<373 kW
>373 kW
HC
EF
4.05
10.1
DF
1.26
1.26
NOx
EF
4.00
6.79
DF
1.03
1.03
CO
EF
96.3
207
DF
1.35
1.35
BSFC
345
362
11A.2 Evaporative Emission Factors
As discussed above, no changes in the proposed hose and tank permeation standards
were considered in the less stringent alternative. The less stringent scenario was modeled for
Small SI equipment by using the baseline running loss and diffusion rates for Class I and Class
II equipment. For marine, the less stringent alternative was modeled by using the baseline
diurnal emission rates for vessels with installed fuel tanks.
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Regulatory Alternatives
APPENDIX 11B: Emission Factors for the More Stringent Alternative
11B.1 Exhaust Emission Factors and Deterioration Rates
1 IB. 1.1 Small SI Exhaust
For analytical purposes, we identified a more stringent program option of 8 g/kW-hr HC
+ NOx standard for Class I engines that would be implemented beginning in 2015. This
standard represents about a 50 reduction from the existing Phase 2 standard, rather than the
approximately 38 percent reduction associated with the proposal. The option also provides 3
more years of lead time. For Class II engines, we identified an alternative for a more stringent
exhaust HC + NOx emission standard of 4.0 g/kW-hr beginning in 2015. (This option also
includes an associated delay in the corresponding proposed running loss requirement such that
engine changes are made simultaneously.) Such an exhaust emission standard represents a 67
percent reduction relative to the existing Phase 2 standard, rather than the 34 percent reduction
associated with the proposal.
In modeling this more stringent option, we assumed the same phase-in schedule that
reflects a number of flexibilities for engine and equipment manufacturers, and allows them to
sell some Phase 2 compliant engines in the early years of the program. We also assumed that
Class I side-valve technology would be completely replaced with overhead valve designs, and
that all of the Class II engines would require closed loop control electronic fuel injection (EFI).
Since EFI equipped engines enjoy a 10 percent fuel consumption advantage over their
carbureted counterparts, we also revised the brake-specific fuel consumption (BSFC) for Class
II engines. The new BSFC value is 0.666 Ib/hp-hr.
All the modeling inputs were developed using a methodology consistent with that
described in Chapter 3 of this draft RIA. The alternative emission standards and phase-in
assumptions are shown in Table B-l. The emission factors are shown in Table B-2.
Table 11B-1: More Stringent Phase 3 Emission Standards and Implementation Schedule
for Class I and II Small SI Engines (g/kW-hr or Percent)
Engine
Class
Class I
Class II
Requirement
HC+NOx
Required Sales
Percentage
HC+NOx
Required Sales
Percentage
2015
8
95
4
83
2016
8
95
4
83
2017
8
100
4
93
2018
8
100
4
93
2019+
8
100
4
100
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Draft Regulatory Impact Analysis
Table 11B-2: More Stringent Phase 3 Modeling Emission Factors
for Small SI Engines (g/KW-hr)
Class/
Technology
Class I - SV
Class I -
Class II
HC
ZML
4.48
4.07
2.13
HC "A"
1.011
1.011
1.011
NOx
ZML
1.12
1.53
NOx "A"
0.470
0.470
0.470
CO ZML
319.76
325.06
391.13
CO "A"
0.070
0.070
0.080
1 IB. 1.2 Marine SI Exhaust
For OB/PWC engines, the more stringent alternative considers exhaust emissions
standards that are about 40 percent lower for HC+NOx and about 30 percent lower for CO than
the proposed primary standard. The more stringent alternative emission standards are modeled
as a second phase of standards, beyond the primary, beginning in 2012. In determining the
combined HC+NOx emission factor, we used the proposed emission standards with a 10
percent compliance margin (with deterioration factor applied). To determine the NOx emission
factors, we used certification data and other emissions data presented in Chapter 4, to determine
the sales weighted average NOx for low emission technologies in each power bin. HC was then
determined as the difference between the HC+NOx and the NOx emission factors. Because we
are proposing the same standards for OB and PWC and because they use similar engines, we
use the same HC+NOx emission factors and deterioration factors for both engine types.
Because the proposed CO standard primarily acts as a cap on CO for many of the engines, the
CO emission factors differ somewhat for CO based on data in the certification database for low
CO engines. We use the same deterioration rates as in the primary case. Table B-3 presents the
zero-hour OB/PWC emission factors used in analyzing the more stringent alternative.
Table B-3: More Stringent Alternative Emission Factors for OB/PWC [g/kW-hr]
Power Bin
0-2.2 kW
2.3-4.5 kW
4.6-8.2 kW
8. 3-1 1.9 kW
12.0-18. 6 kW
18.7-29.8 kW
29.9-37.3 kW
37.4-55. 9 kW
55.9-74.6 kW
74.7-130.5 kW
130.6+ kW
HC
11.7
10.9
10.5
9.0
9.5
7.5
5.7
5.2
5.2
5.4
6.3
NOx
3.02
2.25
3.50
4.22
2.69
3.55
3.70
3.38
3.38
3.13
2.30
CO
OB PWC
362
238
195
165
137
120
114
115
115
101
93
426
359
162
154
145
137
137
137
137
135
119
BSFC
563
560
555
552
543
528
507
471
471
415
387
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Regulatory Alternatives
For SD/I engines greater than 373 kW, we use the same control scenario as for the
primary alternative. However, for SD/I engines less than 373 kW, we considered a more
stringent HC+NOx standard of 2.5 g/kW-hr. To model this standard, we used zero-hour
emission factors of 0.90 g/kW-hr HC and 0.80 g/kW-hr NOx. No changes were made in other
emission factors for this more stringent alternative. In addition, the same deterioration factors
were used here as in the primary alternative.
11B.2 Evaporative Emission Factors
As discussed above, no changes in the proposed hose and tank permeation standards
were considered in the more stringent alternative. The more stringent scenario modeled for
Small SI equipment by considering diurnal standards beginning in 2011 for Class II and 2012
for handheld and Class I equipment. This diurnal emission standards was modeled using a 60
percent reduction from baseline. Also, the more aggressive option for Class II exhaust
standards was modeled as also including a corresponding delay in the proposed running loss
requirement such that engine changes are made simultaneously.
For marine, the more stringent alternative was a standard requiring active purging of
canisters for vessels with installed fuel tanks. This was modeled by using a 70 percent
reduction in diurnal emissions compared to the baseline.
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Draft Regulatory Impact Analysis
Chapter 11 References
1. "Small SI Engine Technologies and Costs, Final Report," ICF International, August 2006.
2. "Marine Outboard and Personal Watercraft SI Engine Technologies and Costs," ICF Consulting, prepared for the
U.S. Environmental Protection Agency, July 2006, Docket Identification EPA-HQ-OAR-2004-0008-0452.
3. "Sterndrive and Inboard Marine SI Engine Technologies and Costs," ICF Consulting, prepared for the U.S.
Environmental Protection Agency, July 2006, Docket Identification EPA-HQ-OAR-2004-0008-0453.
4. "Small SI Engine Technologies and Costs, Final Report," ICF International, August 2006.
5. "Small SI Engine Technologies and Costs, Final Report," ICF International, August 2006.
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