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
Chapter 2 References
1. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
2. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
3. U.S. EPA (2007) Review of National Ambient Air Quality Standards for Ozone, Assessment of Scientific and
Technical Information, OAQPS Staff Paper, EPA-452/R-07-003. This document is available in Docket
EPA-HQ-OAR-2004-0008.
4.Bates, D.V.; Baker-Anderson, M; Sizto, R. (1990) Asthma attack periodicity: a study of hospital emergency visits
in Vancouver. Environ. Res. 51: 51-70.
S.Thurston, G.D.; Ito, K.; Kinney, P.L.; Lippmann, M. (1992) A multi-year study of air pollution and respiratory
hospital admissions in three New York State metropolitan areas: results for 1988 and 1989 summers. J. Exposure
Anal. Environ. Epidemiol. 2:429-450.
6.Thurston, G.D.; Ito, K.; Hayes, C.G.; Bates, D.V.; Lippmann, M. (1994) Respiratory hospital admissions and
summertime haze air pollution in Toronto, Ontario: consideration of the role of acid aerosols. Environ. Res. 65: 271-
290.
7.Lipfert, F.W.; Hammerstrom, T. (1992) Temporal patterns in air pollution and hospital admissions. Environ. Res.
59: 374-399.
S.Burnett, R.T.; Dales, R.E.; Raizenne, M.E.; Krewski, D.; Summers, P.W.; Roberts, G.R.; Raad-Young, M.;
Dann,T.; Brook, J. (1994) Effects of low ambient levels of ozone and sulfates on the frequency of respiratory
admissions to Ontario hospitals. Environ. Res. 65: 172-194.
9. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
10. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
1 I.Devlin, R. B.; McDonnell, W. F.; Mann, R.; Becker, S.; House, D. E.; Schreinemachers, D.; Koren, H. S. (1991)
Exposure of humans to ambient levels of ozone for 6.6 hours causes cellullar and biochemical changes in the lung.
Am. J. Respir. CellMol. Biol. 4: 72-81.
12.Koren, H. S.; Devlin, R. B.; Becker, S.; Perez, R.; McDonnell, W. F. (1991) Time-dependent changes of markers
associated with inflammation in the lungs of humans exposed to ambient levels of ozone. Toxicol. Pathol. 19: 406-
411.
IS.Koren, H. S.; Devlin, R. B.; Graham, D. E.; Mann, R.; McGee, M. P.; Horstman, D. H.; Kozumbo, W. J.; Becker,
S.; House, D. E.; McDonnell, W. F.; Bromberg, P. A. (1989a) Ozone-induced inflammation in the lower airways of
human subjects. Am. Rev. Respir. Dis. 139: 407-415.
2-45
-------
Draft Regulatory Impact Analysis
14.Schelegle, E.S.; Siefkin, A.D.; McDonald, RJ. (1991) Time course of ozone-induced neutrophilia in normal
humans. Am. Rev. Respir. Dis. 143:1353-1358.
15.U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
16.Hodgkin, J.E.; Abbey, D.E.; Euler, G.L.; Magie, A.R. (1984) COPD prevalence in nonsmokers in high and low
photochemical air pollution areas. Chest 86: 830-838.
IV.Euler, G.L.; Abbey, D.E.; Hodgkin, J.E.; Magie, A.R. (1988) Chronic obstructive pulmonary disease symptom
effects of long-term cumulative exposure to ambient levels of total oxidants and nitrogen dioxide in California
Seventh-day Adventist residents. Arch. Environ. Health 43: 279-285.
18.Abbey, D.E.; Petersen, F.; Mills, P.K.; Beeson, W.L. (1993) Long-term ambient concentrations of total
suspended particulates, ozone, and sulfur dioxide and respiratory symptoms in a nonsmoking population. Arch.
Environ. Health 48: 33-46.
19.U.S. EPA. (1996). Review of National Ambient Air Quality Standards for Ozone, Assessment of Scientific and
Technical Information, OAQPS Staff Paper, EPA452-R-96-007. Docket No. A-99-06. Document Identification II-
A-22.
20.U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
21. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
22. Avol, E. L.; Trim, S. C; Little, D. E.; Spier, C. E.; Smith, M. N.; Peng, R.-C; Linn, W. S.; Hackney, J. D.;
Gross, K. B.; D'Arcy, J. B.; Gibbons, D.; Higgins, I. T. T. (1990) Ozone exposure and lung function in children
attending a southern California summer camp. Presented at: 83rd annual meeting and exhibition of the Air & Waste
Management Association; June; Pittsburgh, PA. Pittsburgh, PA: Air & Waste Management Association; paper no.
90-150.3.
23. Higgins, I. T. T.; D'Arcy, J. B.; Gibbons, D. I.; Avol, E. L.; Gross, K. B. (1990) Effect of exposures to ambient
ozone on ventilatory lung function in children. Am. Rev. Respir. Dis. 141: 1136-1146.
24. Raizenne, M. E.; Burnett, R. T.; Stern, B.; Franklin, C. A.; Spengler, J. D. (1989) Acute lung function responses
to ambient acid aerosol exposures in children. Environ. Health Perspect. 79: 179-185.
25. Raizenne, M.; Stern, B.; Burnett, R.; Spengler, J. (1987) Acute respiratory function and transported air
pollutants: observational studies. Presented at: 80th annual meeting of the Air Pollution Control Association; June;
New York, NY. Pittsburgh, PA: Air Pollution Control Association; paper no. 87-32.6.
26. Spektor, D. M.; Lippmann, M. (1991) Health effects of ambient ozone on healthy children at a summer camp.
In: Berglund, R. L.; Lawson, D. R.; McKee, D. J., eds. Tropospheric ozone and the environment: papers from an
international conference; March 1990; Los Angeles, CA. Pittsburgh, PA: Air & Waste Management Association; pp.
83-89. (A&WMA transaction series no. TR-19).
27. Spektor, D. M.; Thurston, G. D.; Mao, J.; He, D.; Hayes, C.; Lippmann, M. (1991) Effects of single- and
multiday ozone exposures on respiratory function in active normal children. Environ. Res. 55: 107-122.
2-46
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Air Quality, Health, and Welfare Concerns
28.Spektor, D. M; Lippman, M; Lioy, P. J.; Thurston, G. D.;s Citak, K.; James, D. I; Bock, N.; Speizer, F. E.;
Hayes, C. (1988a) Effects of ambient ozone on respiratory function in active, normal children. Am. Rev. Respir. Dis.
137:313-320.
29.U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
SO.Hazucha, M. J.; Folinsbee, L. J.; Seal, E., Jr. (1992) Effects of steady-state and variable ozone concentration
profiles on pulmonary function. Am. Rev. Respir. Dis. 146: 1487-1493.
Sl.Horstman, D.H.; Ball, B.A.; Folinsbee, L.J.; Brown, J.; Gerrity, T. (1995) Comparison of pulmonary responses of
asthmatic and nonasthmatic subjects performing light exercise while exposed to a low level of ozone. Toxicol. Ind.
Health.
32.Horstman, D.H.; Folinsbee, L.J.; Ives, P.J.; Abdul-Salaam, S.; McDonnell, W.F. (1990) Ozone concentration and
pulmonary response relationships for 6.6-hour exposures with five hours of moderate exercise to 0.08, 0.10, and 0.12
ppm.Am. Rev. Respir. Dis. 142: 1158-1163.
33. U.S. EPA (2005). Guidance on the Use of Models and Other Analyses in Attainment Demonstrations for the 8-
Hour Ozone NAAQS, Office of Air Quality Planning and Standards, Research Triangle Park, NC. EPA document #
EPA-454/R-05-002. This document is contained in Docket Identification EPA-HQ-OAR-2004-0008-0464.
34. U.S. Environmental Protection Agency, 1999. The Benefits and Costs of the Clean Air Act, 1990-2010.
Prepared for U.S. Congress by U.S. EPA, Office of Air and Radiation, Office of Policy Analysis and Review,
Washington, DC, November; EPA report no. EPA410-R-99-001. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0485.
35. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
36. Winner, W.E., and C.J. Atkinson. 1986. Absorption of air pollution by plants, and consequences for growth.
Trends in Ecology and Evolution 1:15-18.
37. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
38. Tingey, D.T., and Taylor, G.E. 1982. Variation in plant response to ozone: a conceptual model of physiological
events. In: Effects of Gaseous Air Pollution in Agriculture and Horticulture (Unsworth, M.H., Omrod, D.P., eds.)
London, UK: Butterworth Scientific, pp. 113-138.
39. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
40. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
41. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
2-47
-------
Draft Regulatory Impact Analysis
42. Ollinger, S.V., J.D. Aber and P.B. Reich. 1997. Simulating ozone effects on forest productivity: interactions
between leaf canopy and stand level processes. Ecological Applications 7:1237-1251.
43. Winner, W.E., 1994. Mechanistic analysis of plant responses to air pollution. Ecological Applications,
4(4):651-661.
44. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
45. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
46. Fox, S., and R. A. Mickler, eds.. 1996. Impact of Air Pollutants on Southern Pine Forests. Springer-Verlag, NY,
Ecol. Studies, Vol. 118, 513 pp.
47. National Acid Precipitation Assessment Program (NAPAP), 1991. National Acid Precipitation Assessment
Program. 1990 Integrated Assessment Report. National Acid Precipitation Program. Office of the Director,
Washington DC. This document is contained in Docket Identification EPA-HQ-OAR-2004-0008-0489.
48. De Steiguer, I, J. Pye, C. Love. 1990. Air pollution Damage to U.S. forests. Journal of Forestry, Vol 88(8) pp.
17-22.
49. Pye, J.M. Impact of ozone on the growth and yield of trees: A review. Journal of Environmental Quality 17
pp.347-360., 1988.
50. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
51. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
52. McBride, J.R., P.R. Miller, and R.D. Laven. 1985. Effects of oxidant air pollutants on forest succession in the
mixed conifer forest type of southern California. In: Air Pollutants Effects On Forest Ecosystems, Symposium
Proceedings, St. P, 1985, p. 157-167.
53. Miller, P.R., O.C. Taylor, R.G. Wilhour. 1982. Oxidant air pollution effects on a western coniferous forest
ecosystem. Corvallis, OR: U.S. Environmental Protection Agency, Environmental Research Laboratory (EPA600-D-
82-276).
54. U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket
Identification EPA-HQ-OAR-2004-0008-0455 to 0457.
55. Kopp, R. J.; Vaughn, W. J.; Hazilla, M.; Carson, R. 1985. Implications of environmental policy for U.S.
agriculture: the case of ambient ozone standards. J. Environ. Manage. 20:321-331.
56. Adams, R. M.; Hamilton, S. A.; McCarl, B. A. 1986. The benefits of pollution control: the case of ozone and
U.S. agriculture. Am. J. Agric. Econ. 34: 3-19.
2-48
-------
Air Quality, Health, and Welfare Concerns
57. Adams, R. M; Glyer, J. D.; Johnson, S. L.; McCarl, B. A. 1989. A reassessment of the economic effects of
ozone on U.S. agriculture. JAPCA 39:960-968.
58. Abt Associates, Inc. 1995. Urban ornamental plants: sensitivity to ozone and potential economic losses. U.S.
EPA, Office of Air Quality Planning and Standards, Research Triangle Park. Under contract to RADIAN
Corporation, contract no. 68-D3-0033, WA no. 6. pp. 9-10.
59. U.S. EPA (2004) Air Quality Criteria for Paniculate Matter. Document Nos. EPA/600/P-99/002aF and
EPA/600/P-99/002bF. This document is available in Docket EPA-HQ-OAR-2004-0008-0042 and EPA-HQ-OAR-
2004-0008-0043.
60. U. S. EPA (2005) Review of the National Ambient Air Quality Standard for Paniculate Matter: Policy
Assessment of Scientific and Technical Information, OAQPS Staff Paper. EPA-452/R-05-005. This document is
available in Docket EPA-HQ-OAR-2004-0008-0454.
61.U.S. EPA 2006. Provisional Assessment of Recent Studies on Health Effects of Paniculate Matter Exposure.
EPA/600/R-06/063. This document is available in Docket EPA-HQ-OAR-2004-0008-0461.
62. Laden F; Neas LM; Dockery DW; et al. (2000). Association of fine paniculate matter from different sources
with daily mortality in six U.S. cities. Environ Health Perspectives 108(10):941-947.
63. Schwartz J; Laden F; Zanobetti A. (2002). The concentration-response relation between PM(2.5) and daily
deaths. Environ Health Perspect 110(10): 1025-1029.
64. Janssen NA; Schwartz J; Zanobetti A.; et al. (2002). Air conditioning and source-specific particles as modifiers
of the effect of PM10 on hospital admissions for heart and lung disease. Environ Health Perspect 110(l):43-49.
65. Dockery, DW; Pope, CA, III; Xu, X; et al. (1993). An association between air pollution and mortality in six U.S.
cities. NEnglJMed 329:1753-1759.
66. Pope, CA, III; Burnett, RT; Thun, MJ; Calle, EE; et al. (2002) Lung cancer, cardiopulmonary mortality, and
long-term exposure to fine paniculate air pollution. JAmMedAssoc 287: 1132-1141.
67. Krewski, D; Burnett, RT; Goldberg, M S; et al. (2000) Reanalysis of the Harvard Six Cities study and the
American Cancer Society study of paniculate air pollution and mortality. A special report of the institute's Particle
Epidemiology Reanalysis Project. Cambridge, MA: Health Effects Institute.
68Jerrett, M; Burnett, RT; Ma, R; et al. 2005. "Spatial Analysis of Air Pollution and Mortality in Los Angeles."
Epidemiology. 16(6):727-736.
69. Ktinzli, N.; Jerrett, M.; Mack, W.J.; et al.(2004) Ambient air pollution and atherosclerosis in
Los Angeles. Environ Health Perspect doi: 10.1289/ehp.7523 [Available at http://dx.doi.org/].
70.Riediker, M.; Cascio, W.E.; Grtggs, T.R.; et al. 2004. "Paniculate matter exposure in cars is associated with
cardiovascular effects in healthy young men." Am JRespir Crit Care Med 169: 934-940.
71.Van Vliet, P.; Knape, M.; de Hartog, J.; Janssen, N.; Harssema, H.; Brunekreef, B. (1997). Motor vehicle
exhaust and chronic respiratory symptoms in children living near freeways. Env. Research 74: 122-132.
72.Brunekreef, B., Janssen, N.A.H.; de Hartog, J.; Harssema, H.; Knape, M.; van Vliet, P. (1997). Air pollution
from truck traffic and lung function in children living near roadways. Epidemiology 8:298-303.
2-49
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73.Kim, J.J.; Smorodinsky, S.; Lipsett, M.; Singer, B.C.; Hodgson, A.T.; Ostro, B (2004). Traffic-related air
pollution near busy roads: The East Bay children's respiratory health study. Am. J. Respir. Crit. Care Med. 170:
520-526.
74.National Research Council, 1993. Protecting Visibility in National Parks and Wilderness Areas. National
Academy of Sciences Committee on Haze in National Parks and Wilderness Areas. National Academy Press,
Washington, DC. This document is available in Docket EPA-HQ-OAR-2004-0008-0488. This book can be viewed
on the National Academy Press Website at http://www.nap.edu/books/0309048443/html/
75.See discussion in U.S. EPA , National Ambient Air Quality Standards for Paniculate Matter; Proposed Rule;
January 17, 2006, Vol71 p2676. This document is available in Docket EPA-HQ-OAR-2004-0008-0466. This
information is available electronically at http://epa.gov/fedrgstr/EPA-AIR/2006/January/Day-17/al77.pdf
76. U.S. EPA (2004) Air Quality Criteria for Paniculate Matter. Document Nos. EPA/600/P-99/002aF and
EPA/600/P-99/002bF. This document is available in Docket EPA-HQ-OAR-2004-0008-0042 and EPA-HQ-OAR-
2004-0008-0043.
77. U. S. EPA (2005) Review of the National Ambient Air Quality Standard for Paniculate Matter: Policy
Assessment of Scientific and Technical Information, OAQPS Staff Paper. EPA-452/R-05-005. This document is
available in Docket EPA-HQ-OAR-2004-0008-0454.
78. U.S. EPA (2005). Technical Support Document for the Final Clean Air Interstate Rule - Air Quality Modeling.
This document is available in Docket EPA-HQ-OAR-2004-0008-0484.
79.U.S. EPA. 2006. Regulatory Impact Analysis for the final PM NAAQS. This document is available in Docket
EPA-HQ-OAR-2004-0008.
80. U. S. EPA (2005) Review of the National Ambient Air Quality Standard for Paniculate Matter: Policy
Assessment of Scientific and Technical Information, OAQPS Staff Paper. EPA-452/R-05-005. This document is
available in Docket EPA-HQ-OAR-2004-0008-0454.
81. U.S. EPA. 1993. Effects of the 1990 Clean Air Act Amendments on Visibility in Class I Areas: An EPA Report
to Congress. EPA452-R-93-014. This document is available in Docket EPA-HQ-OAR-2004-0008-0483.
82.U.S. EPA (2002) Latest Findings on National Air Quality - 2002 Status and Trends. EPA 454/K-03-001. This
document is available in Docket EPA-HQ-OAR-2004-0008-0482.
83. National Park Service. Air Quality in the National Parks, Second edition. NFS, Air Resources Division. D
2266. September 2002. This document is available in Docket EPA-HQ-OAR-2004-0008-0481.
84.U.S. EPA (2002) Latest Findings on National Air Quality - 2002 Status and Trends. EPA 454/K-03-001. This
document is available in Docket EPA-HQ-OAR-2004-0008-0482.
85. U.S. EPA. 1993. Effects of the 1990 Clean Air Act Amendments on Visibility in Class I Areas: An EPA Report
to Congress. EPA452-R-93-014. This document is available in Docket EPA-HQ-OAR-2004-0008-0483.
86. U.S. EPA (2005). Technical Support Document for the Final Clean Air Interstate Rule - Air Quality Modeling.
This document is available in Docket EPA-HQ-OAR-2004-0008-0484.
87. U.S. EPA (2003) Guidance for Tracking Progress Under the Regional Haze Rule. EPA-454/B-03-004. This
document is available in Docket EPA-HQ-OAR-2004-0008-0487.
88.U.S. EPA (2000) Deposition of Air Pollutants to the Great Waters: Third Report to Congress. Office of Air
Quality Planning and Standards. EPA-453/R-00-0005.
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89.U.S. EPA (2004) National Coastal Condition Report II. Office of Research and Development/ Office of Water.
EPA-620/R-03/002.
90.Gao, Y., E.D. Nelson, M.P. Field, et al. 2002. Characterization of atmospheric trace elements onPM2.5
particulate matter over the New York-New Jersey harbor estuary. Atmos. Environ. 36: 1077-1086.
91.Kim, G., N. Hussain, J.R. Scudlark, and T.M. Church. 2000. Factors influencing the atmospheric depositional
fluxes of stable Pb, 210Pb, and 7Be into Chesapeake Bay. J. Atmos. Chem. 36: 65-79.
92.Lu, R., R.P. Turco, K. Stolzenbach, et al. 2003. Dry deposition of airborne trace metals on the Los Angeles Basin
and adjacent coastal waters. J. Geophys. Res. 108(D2, 4074): AAC 11-1 to 11-24.
93.Marvin, C.H., M.N. Charlton, E.J. Reiner, et al. 2002. Surficial sediment contamination in Lakes Erie and
Ontario: A comparative analysis. J. Great Lakes Res. 28(3): 437-450.
94. Much of the information in this subsection was excerpted from the EPA document, Human Health Benefits from
Sulfate Reduction, written under Title IV of the 1990 Clean Air Act Amendments, U.S. EPA, Office of Air and
Radiation, Acid Rain Division, Washington, DC 20460, November 1995.
95 Acid Rain: Emissions Trends and Effects in the Eastern United States, U.S. General Accounting Office, March,
2000 (GOA/RCED-00-47).
96. Acid Deposition Standard Feasibility Study: Report to Congress, EPA430-R-95-001a, October, 1995.
97.Deposition of Air Pollutants to the Great Waters, Third Report to Congress, June 2000, EPA-453/R-00-005.
This document can be found in Docket No. OAR-2002-0030, Document No. OAR-2002-0030-0025. It is also
available at www.epa.gov/oar/oaqps/gr8water/3rdrpt/obtain.html.
98. Bricker, Suzanne B., et al., National Estuarine Eutrophication Assessment, Effects of Nutrient Enrichment in the
Nation's Estuaries, National Ocean Service, National Oceanic and Atmospheric Administration, September, 1999.
99. Deposition of Air Pollutants to the Great Waters, Third Report to Congress, June, 2000.
100. Valigura, Richard, et al., Airsheds and Watersheds II: A Shared Resources Workshop, Air Subcommittee of the
Chesapeake Bay Program, March, 1997.
101. The Impact of Atmospheric Nitrogen Deposition on Long Island Sound, The Long Island Sound Study,
September, 1997.
102. Dennis, Robin L., Using the Regional Acid Deposition Model to Determine the Nitrogen Deposition Airshed of
the Chesapeake Bay Watershed, SET AC Technical Publications Series, 1997.
103. Dennis, Robin L., Using the Regional Acid Deposition Model to Determine the Nitrogen Deposition Airshed of
the Chesapeake Bay Watershed, SET AC Technical Publications Series, 1997.
104. Wedin, D.A. and D. Tilman. 1996. Influence of nitrogen loading and species composition on the carbon balance
of grasslands. Science 274:1720-1723.
105.Smith, W.H. 1991. Air pollution and forest damage." Chemical Engineering News, 69(45): 30-43.
106.Gawel, J.E.; Ahner, B.A.; Friedland, A.J.; and Morel, F.M.M. 1996. Role for heavy metals in forest decline
indicated by phytochelatin measurements. Nature, 381: 64-65.
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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
decomposition in Quercus ilix L. woods. Environmental Pollution, 89: 81-87.
lOS.Niklinska, M.; Laskowski, R.; Maryanski, M. 1998. Effect of heavy metals and storage time on two types of
forest litter: basal respiration rate and exchangeable metals. Ecotoxicological Environmental Safety, 41: 8-18.
109.Mason, R.P. and Sullivan, K.A. 1997. Mercury in Lake Michigan. Environmental Science & Technology, 31:
942-947. (from Delta Report "Atmospheric deposition of toxics to the Great Lakes")
1 lO.Landis, M.S. and Keeler, G.J. 2002. Atmospheric mercury deposition to Lake Michigan during the Lake
Michigan Mass Balance Stady. Environmental Science & Technology, 21: 4518-24.
11 l.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
available in Docket EPA-HQ-OAR-2004-0008.
112.Callender, E. and Rice, K.C. 2000. The urban environmental gradient: Anthropogenic influences on the spatial
and temporal distributions of lead and zinc in sediments. Environmental Science & Technology, 34: 232-238.
HS.Rice, K.C. 1999. Trace element concentrations in streambed sediment across the conterminous United States.
Environmental Science & Technology, 33: 2499-2504.
114.Ely, JC; Neal, CR; Kulpa, CF; etal. 2001. Implications of platinum-group element accumulation along U.S.
roads from catalytic -converter attrition. Environ. Sci. Technol. 35: 3816-3822.
115.U.S. EPA. 1998. EPA454/R-98-014, "Locating and Estimating Air Emissions from Sources of Polycyclic
Organic Matter," Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina. This
document is available in Docket EPA-HQ-OAR-2004-0008.
116.U.S. EPA. 1998. EPA454/R-98-014, "Locating and Estimating Air Emissions from Sources of Polycyclic
Organic Matter," Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina. This
document is available in Docket EPA-HQ-OAR-2004-0008.
117.Simcik, M.F.; Eisenreich, S.J.; Golden, K.A.; et al. 1996. Atmospheric loading of polycyclic aromatic
hydrocarbons to Lake Michigan as recorded in the sediments." Environmental Science and Technology, 30:
3039-3046.
1 IS.Simcik, M.F.; Eisenreich, S.J.; and Lioy, P.J. 1999. Source apportionment and source/sink relationship of PAHs
in the coastal atmosphere of Chicago and Lake Michigan. Atmospheric Environment, 33: 5071-5079.
119.Arzayus, K.M.; Dickhut, R.M.; and Canuel, E.A. 2001. Fate of atmospherically deposited polycyclic aromatic
hydrocarbons (PAHs) in Chesapeake Bay." Environmental Science & Technology, 35, 2178-2183.
120.Park, J.S.; Wade, T.L.; and Sweet, S. 2001. Atmospheric distribution of polycyclic aromatic hydrocarbons and
deposition to Galveston Bay, Texas, USA. Atmospheric Environment, 35: 3241-3249.
121.Poor, N.; Tremblay, R.; Kay, H.; et al. 2002. Atmospheric concentrations and dry deposition rates of polycyclic
aromatic hydrocarbons (PAHs) for Tampa Bay, Florida, USA. Atmospheric Environment 38: 6005-6015.
122.Arzayus, K.M.; Dickhut, R.M.; and Canuel, E.A. 2001. Fate of atmospherically deposited polycyclic aromatic
hydrocarbons (PAHs) in Chesapeake Bay. Environmental Science & Technology, 35, 2178-2183.
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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
available in Docket EPA-HQ-OAR-2004-0008.
124.Van Metre, P.C.; Mahler, B.J.; and Furlong, E.T. 2000. Urban sprawl leaves its PAH signature." Environmental
Science & Technology, 34: 4064-4070.
125.Cousins, I.T.; Beck, A.J.; and Jones, K.C. 1999. A review of the processes involved in the exchange of
semi-volatile organic compounds across the air-soil interface. The Science of the Total Environment, 228: 5-24.
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
Assessment of Scientific and Technical Information, OAQPS Staff Paper. EPA-452/R-05-005. This document is
available in Docket EPA-HQ-OAR-2004-0008-0454.
128.U.S. EPA (2000). Integrated Risk Information System File for Benzene. This material is available electronically
at http://www.epa.gov/iris/subst/0276.htm
129.1nternational Agency for Research on Cancer, IARC monographs on the evaluation of carcinogenic risk of
chemicals to humans, Volume 29, Some industrial chemicals and dyestuffs, International Agency for Research on
Cancer, World Health Organization, Lyon, France, p. 345-389, 1982.
130.Irons, R.D.; Stillman, W.S.; Colagiovanni, D.B.; Henry, V.A. (1992) Synergistic action of the benzene
metabolite hydroquinone on myelopoietic stimulating activity of granulocyte/macrophage colony-stimulating factor
in vitro, Proc. Natl. Acad. Sci. 89:3691-3695.
131.Aksoy, M. (1989). Hematotoxicity and carcinogenicity of benzene. Environ. Health Perspect. 82:193-197.
132.Goldstein, B.D. (1988). Benzene toxicity. Occupational medicine. State of the Art Reviews. 3:541-554.
133.Rothman, N., G.L. Li, M. Dosemeci, W.E. Bechtold, G.E. Marti, Y.Z. Wang, M. Linet, L.Q. Xi, W. Lu, M.T.
Smith, N. Titenko-Holland, L.P. Zhang, W. Blot, S.N. Yin, and R.B. Hayes (1996) Hematotoxicity among Chinese
workers heavily exposed to benzene. Am. J. Ind. Med. 29: 236-246.
134.EPA 2005 "Full IRIS Summary for Benzene (CASRN 71-43-2)" Environmental Protection Agency, Integrated
Risk Information System (IRIS), Office of Health and Environmental Assessment, Environmental Criteria and
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.;
Rupa, D.; Suramaya, R.; Songnian, W.; Huifant, Y.; Meng, M.; Winnik, M.; Kwok, E.; Li, Y.; Mu, R.; Xu, B.;
Zhang, X.; Li, K. (2003). HEI Report 115, Validation & Evaluation of Biomarkers in Workers Exposed to Benzene
in China.
136.Qu, Q., R. Shore, G. Li, X. Jin, L.C. Chen, B. Cohen, et al. (2002). Hematological changes among Chinese
workers with a broad range of benzene exposures. Am. J. Industr. Med. 42: 275-285.
137.Lan, Qing, Zhang, L., Li, G., Vermeulen, R., et al. (2004). Hematotoxically in Workers Exposed to Low Levels
of Benzene. Science 306: 1774-1776.
138.Turtletaub, K.W. and Mani, C. (2003). Benzene metabolism in rodents at doses relevant to human exposure
from Urban Air. Research Reports Health Effect Inst. Report No. 113.
2-53
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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.
EPA-SAB-EHC-98.
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
lymphohematopoetic malignancies among workers in formaldehyde industries. Journal of the National Cancer
Institute 95: 1615-1623.
144.Hauptmann, M..; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.; Blair, A. 2004. Mortality from solid cancers
among workers in formaldehyde industries. American Journal of Epidemiology 159: 1117-1130.
145.Pinkerton, L. E. 2004. Mortality among a cohort of garment workers exposed to formaldehyde: an update.
Occup. Environ. Med. 61: 193-200.
146.Conolly, RB, JS Kimbell, D Janszen, PM Schlosser, D Kalisak, J Preston, and FJ Miller. 2003. Biologically
motivated computational modeling of formaldehyde carcinogenicity in the F344 rat. Tox Sci 75: 432-447.
147.Conolly, RB, JS Kimbell, D Janszen, PM Schlosser, D Kalisak, J Preston, and FJ Miller. 2004. Human
respiratory tract cancer risks of inhaled formaldehyde: Dose-response predictions derived from
biologically-motivated computational modeling of a combined rodent and human dataset. Tox Sci 82: 279-296.
148.Chemical Industry Institute of Toxicology (CUT). 1999. Formaldehyde: Hazard characterization and
dose-response assessment for carcinogenicity by the route of inhalation. CUT, September 28, 1999. Research
Triangle Park, NC.
149.Health Canada (2001) Priority Substances List Assessment Report. Formaldehyde. Environment Canada, Health
Canada, February 2001. The document may be accessed at
http://www.hc-sc.gc.ca/ewh-semt/pubs/contaminants/psl2-Isp2/formaldehyde/index_e.html.
ISO.Coggon, D, EC Harris, J Poole, KT Palmer. 2003. Extended follow-up of a cohort of British chemical workers
exposed to formaldehyde. J National Cancer Inst. 95: 1608-1615.
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.
2-54
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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.
http://cfpub2.epa.gov/ncea/cfm/recordisplay.cfm?deid=86019
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
copy of this document is available in Docket Identification EPA-HQ-OAR-2004-0008-0050.
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
Monoxide (Penney, D.G., ed). Boca Raton, CRC Press, 69-86.
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 h |