EPA-AA-SRPB-93-01
Lifetime Emissions
for Clean-Fuel Fleet Vehicles
Notice
Technical reports do not necessarily represent final EPA decisions or positions. They are
intended to present technical analyses of issues using data which are currently available. The
purpose in the release of such reports is to facilitate the exchange of technical developments
which may form the basis for a final EPA decision, position, or regulatory action.
U.S. Environmental Protection Agency
Office of Mobile Sources
Regulation Development and Support Division
Ann Arbor, Michigan
October 1993
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This document presents EPA's current estimates for the emissions produced by several
types of vehicles which may be purchased in response to the Clean Air Act Clean-Fuel Fleet
Program. Attached are appendices which include a more detailed explanation of how EPA
generated the values presented in the tables and which also discusses how these estimates might
be improved in the future.
Summary
Fleet operators have two general options in purchasing vehicles to comply with the Clean-
Fuel Fleet Program: 1) Basic clean-fuel vehicles, which meet standards equivalent to the
California Low-Emission Vehicle (LEV) exhaust emission standards, and 2) Inherently Low-
Emission Vehicles (ILEVs), which meet LEV exhaust standards but also have inherently low
evaporative emissions.
The results presented in this report project that substituting ELEVs for basic clean-fuel
vehicles will result in significant additional emission reductions due to the vehicles' extremely
low evaporative emissions. How large a fraction of overall vehicle hydrocarbon emissions this
evaporative benefit represents depends on how well the control of tailpipe emissions is
maintained over the life of the vehicle. Although the type of inspection and maintenance (I/M)
program does not affect the absolute evaporative emission reduction, a more aggressive I/M
program will result in a greater relative impact of ILEVs compared to basic clean-fuel vehicles.
Specifically, this report concludes that under Enhanced I/M programs, substituting an
ILEV for a basic clean-fuel fleet vehicle will result in a 26 percent improvement in hydrocarbon
emissions for each vehicle. Under a more aggressive I/M program (Maximum I/M), substituting
ILEVs for a clean-fuel vehicle will result in a 64 percent improvement. Compared to a standard
federal (Tier 1) vehicle, the reductions are greater (55 percent and 85 percent under Enhanced
I/M and Max I/M programs, respectively).
Background
The Clean Air Act Amendments of 1990 incorporated a concept originated by the
California Air Resources Board of defining several vehicle emission categories representing
emission levels lower than those applying to conventional vehicles. These "Low-Emission
Vehicle" or LEV standards include permissible exhaust emissions for certifying vehicles as LEVs,
Ultra Low-Emission Vehicles (ULEVs), and Zero-Emission Vehicles (ZEVs). Exhaust emission
standards for each of these categories are more stringent than the "Tier 1" vehicles standards,
which are the lowest required federal standards for non-California vehicles produced for the
general public after the mid-1990s. Because the standards are based on emission performance,
not fuel type, vehicles can certify as LEVs, ULEVs, or ZEVs on any fuel on which they meet
the standards.
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In addition, EPA has established an additional clean vehicle emission category known as
"Inherently Low-Emission Vehicles" or ILEVs. To qualify as HJEVs, vehicles must first qualify
as LEVs and then meet additional criteria. The primary ILEV criterion is that the vehicle
inherently emit little or no evaporative emissions even if the evaporative emission controls
malfunction, as has often occurred in actual use. Also, an ILEV must meet the LEV exhaust
standards for hydrocarbons and carbon monoxide and the ULEV standards for nitrogen oxides.
(A vehicle must meet the ILEV requirements on all fuels it is capable of using.) As with the
LEV categories, a vehicle operating on any fuel or fuels that meets these criteria can qualify as
an ILEV; the most likely vehicles to be certified as ILEVs will be pure alcohol vehicles (100
percent methanol or ethanol), dedicated gaseous fuel vehicles (compressed natural gas or liquified
petroleum gas (propane)), or electric vehicles (in which case ILEVs may also be ZEVs).
Vehicles which can operate on more than one fuel may be DLEVs if they meet the requirements
on each fuel.
There are a growing number of local, state, and national programs in which LEVs,
ULEVs, ZEVs, and/or ILEVs play a role. These include 1) California's LEV program (which
several states have adopted or are considering adopting); 2) the federal Clean-Fuel Fleet program
and the California Pilot Program (federal Clean Air Act programs which introduce the concept
of "Clean-Fuel Vehicles" or CFVs, equivalent in their emission requirements to LEVs.); 3) the
implementation of the federal fleet provisions of the Energy Policy Act (which the Federal Fleet
Conversion Task Force has recommended focus on cleaner vehicles than would otherwise have
been required); and 4) A variety of programs initiated at the state and local level to accelerate
the introduction of alternative fuel vehicles into fleets. For a variety of reasons including air
quality and compliance with Clean Air Act and Energy Policy Act fleet programs, policy makers
at all levels of government are considering programs that would mandate or offer incentives for
the purchase of LEVs, ULEVs, ZEVs, or ILEVs.
Vehicle Emission Levels
Figure 1 and Table 1 present EPA's most recent emission estimates for non-methane
hydrocarbons (NMHC) from LEV, ULEV, and ILEV vehicles in terms of grams per mile traveled
(g/mi) per vehicle. (Estimates of ZEV emissions, including electric power plant emissions, are
currently under development by EPA and are not included here.) Two sets of emission values
are presented to illustrate the effect that the intensity of local inspection and maintenance (I/M)
programs has on the emissions of each vehicle type. "Enhanced I/M" represents test-only
programs using the IM240 transient emission test which will be implemented in many cities.
"Max I/M" represents a very rigorous I/M program (for example, for fleet applications) which
could return vehicles failing the test to very nearly their certified values.
All the values in Table 1 include the assumptions that vehicles are designed to comply
with the recently finalized improved evaporative emission control requirements and with the
proposed onboard refueling control requirements. (Technically, these programs will not affect all
vehicles until late in the 1990's; total vapor emissions (evaporative plus refueling) will actually
be somewhat higher in the interim). The values assume both certification and operation on the
same fuel (federal or California reformulated gasoline), since the Clean Air Act Clean-Fuel Fleet
program requires use of the certification fuel in covered areas.
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Reductions
Figure 2 and Table 2 present a key comparison of emissions values from Table 1. In this
table, emissions from clean-fuel vehicles certified as ILEVs are compared to those of clean-fuel
vehicles certified as LEVs, the vehicles which ILEVs will most often replace. This table
illustrates the significant additional emission reductions that ILEVs will offer beyond those
available for basic LEV/CFV vehicles. For an aggressive I/M program like the one modeled for
Max I/M, the table shows that the reduction numbers for ILEVs would be much higher.
Figure 3 -and Table 3 compare emissions of LEVs, ULEVs, and ILEVs (all of which are
also CFVs for purposes of the Clean Air Act programs) to the emissions of Tier 1 vehicles. The
results illustrate that LEVs and ULEVs offer similar reductions to one another; again, ILEV
reductions are seen to be significantly higher, especially under a Max I/M program.
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Figure I/Table 1
Lifetime Exhaust + Vapor NMHC Emission Factors
Light-Duty Clean Fuel Fleat Vehicles (a/ml)
Feder«IRFG2 CARFQ
LB/
FBCJWIIRF02 CARFG
ULB/
I Max I'M 0 Bihanced Wl
Lifetime NMHC Emission Factors (g/mi)
Light-Duty Clean-Fuel Fleet Vehicles
CFV/LEV
Ortifird and operated on:
Federal RFG 2
CARFG
CFV/ULEV
Certified and operated on:
Federal RFG 2
CARFG
ILEV
Coi luted end operated ont
All Fuels1
Enhanced I/M
exhaust
0.429
0.429
0.407
0.407
0.429
vapor
0.153
0.119
0.153
0.118
O.OOO2
Max I/M
exhaust
0.084
0.084
0.045
0.045
0.084
vapor
0.153
0.118
0.153
0.118
O.OOO2
'"'Assumes similar average exhaust emissions to gasoline CFVs (LEVs).
4
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Figure 2/Table 2
Lifetime Exhaust + Vapor NMHC Emission Reductions
(LEV Compared to CFV (LEV) Certified and Operated on Federal RFG2
-100
Lifetime Exhaust + Vapor NMHC Emission Reductions (g/mi)
BLEV Compared to CFV (LEV) Certified and Operated on Federal RFC 2
ILEV
Certified Bno oponfiBo on!
All Fuels
Enhanced I/M
0.153 (26%)
Max I/M
0.153 (64%)
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-100
Figure 3/ Table 3
Lifetime Exhaust + Vapor NMHC Emission Reductions
Compared to Tier 1 Vehicle Certified and Operated on Baseline Fuel
Fxfaral RFO 2 CA RFO
LEV
F«taralRFQ2 CA RFO
ULEV
AIFu«U
ILB/
I Enhanced VM & Max VM
Lifetime Exhaust + Vapor NMHC Emission Reductions (g/mi)
Compared to Tier 1 Vehicle Certified and Operated on Baseline Fuel
CFV/LEV
Certified ind operated on:
Federal RFG 2
CARFG
CFV/ULEV
Certified «nd openied on:
Federal RFG 2
CARFG
ILEV
Certified and operated on:
All Fuels
Enhanced I/M
0.361 (38%)
0.395 (42%)
0.383 (41%)
0.418 (44%)
0.514(55%)
Max I/M
0.320 (57%)
0.355 (64%)
0.359 (64%)
0.394 (71%)
0.473 (85%)
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Appendix A
Calculation Methodology and Potential Future Changes
EPA has generated average lifetime emission estimates and emission reductions for
vehicles certified to meet the various emission standards available to fleet vehicles. With a few
exceptions, these estimates are generated by the released version of EPA's latest highway motor
vehicle emission factor model, MOBILESa. This paper assumes the reader has a working
knowledge of the MOBILESa model. The MOBILE5a computer model and Users Guide is
available through EPA's Office of Air Quality Planning and Standards Technology Transfer
Network Bulletin Board System (OAQPS TTNBBS) at 919/541-5742. (Voice help is available
at 919/541-5384.)
Several MOBELESa runs were made under various input conditions to produce the average
emission factors for the year 2020 presented in the tables in the main report and in Appendix B.
Choosing a point this far in the future models a situation in which essentially all vehicles
incorporate vehicle emission control changes made within the next few years.
Basic Methodology
For each vehicle emission category modeled (Tier 1, LEV, ULEV, and ILEV2), we
performed specialized runs of MOBILESa as though the entire fleet of vehicles were of that
category. A Year 2020 run done in this manner permits the model to calculate an average
lifetime emission factor incorporating a full range of vehicle ages and mileage accumulations.
These specialized MOBILESa runs were performed for each emission category by "forcing" the
model to run as though all vehicles were of the same type using an undocumented feature that
allows the user to input different numbers of vehicles in the California LEV program.
Each run involved several common parameters. (See the attached input files in Appendix
C for further details on input parameters.) The runs were set for July 1 evaluation with a
temperature range of 71.6 to 91.6°F with an ambient temperature of 87.6°F. Average vehicle
speed used was 19.6 miles per hour (FTP speed). Operating mode percentages are 20.6,27.3 and
20.6 for cold-start non-catalyst vehicles, hot-start catalyst-equipped vehicles and cold-start
catalyst-equipped vehicles, respectively. An onboard refueling vapor recovery system applicable
to all vehicle types was modeled to begin in 1998.
Case-Specific Assumptions
In order to produce emission estimates for a variety of potential in-use scenarios, the basic
methodology was repeated while several parameters were varied. Details of the runs are found
2Zero-Emission vehicles (ZEVs) are not included in this analysis. EPA is currently evaluating appropriate
emission factors for electric vehicles which account for power-plant emissions.
A - 1
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in the attached MOBILESa input files. We ran scenarios simulating two inspection/maintenance
(I/M) programs, "Enhanced I/M" and "Maximum I/M." Enhanced I/M is modeled for an IM240
transient test with 0.8 grams/mile HC cutpoint and anti-tampering checks on catalyst removal and
fuel inlet restrictor disablements, and pressure and purge checks on the evaporative emission
control systems. This represents centralized programs using the IM240 emission test, as
established in the 5 November 1992 I/M final rule (57 FR 52950).
"Maximum I/M" or "Max I/M" simulates a very rigorous program capable of returning
failed vehicles very nearly to their certified values. Such a program does not yet exist, but may
be considered by states seeking additional emission reductions, especially for fleet vehicles.
Physically, it is modeled in MOBILESa by setting IMFLAG to 4 which imposes a Max I/M
program on Tier 1 vehicles. For LEVs and ULEVs, the first flag in the scenario descriptive
record can be set to induce the Max I/M program.
Another goal was to estimate the effect of different fuels on emissions. For the modeling
of LEVs, ULEVs, and ILEVs, we assumed that vehicles were certified and operated on the same
fuel. This would occur by law under the Clean Air Act Clean-Fuel Fleet program, which requires
in Section 246(b) that clean-fuel vehicles use the clean fuel on which they are certified when
operating in covered areas. For this analysis, we generated estimates for LEVs, ULEVs, and
ILEVs certified on and operating on federal Phase 2 reformulated gasoline and California Phase
2 reformulated gasoline. Although some fuels are cleaner-burning than others, it is assumed that
manufacturers would use any additional emissions benefit of a given fuel to help meet the
exhaust emission standards. Thus, all of these vehicles, regardless of the fuel they are certified
(and operated) on are modeled as having the same exhaust emissions. Federal Phase 2
reformulated gasoline is modeled by MOBILESa with the reformulated fuel flag in the local area
parameter (LAP) record. California Phase 2 gasoline effects are modeled by inputting the fuel's
assumed RVP (6.9 RVP) into the model to determine the vapor effects, and the exhaust effects
are determined outside of the model using the estimated reduction in exhaust emissions from
baseline fuel (29%).
For the modeling of Tier 1 vehicles, we assumed certification testing was performed on
standard EPA test fuel ("indolene"), with separate simulations of the operation of vehicles on
"baseline" in-use fuel (as defined in the Clean Air Act), federal Phase 2 reformulated gasoline,
and California Phase 2 reformulated gasoline. The use of baseline fuel is inherent to the model.
The exhaust and evaporative emissions of the vehicles operating on federal and California
reformulated gasolines were modeled as discussed above for LEVs, ULEVs, and ILEVs. The
results of the Tier 1 modeling appear in Appendix B.
Potential Effect of New Data and Analysis on MOBILESa Assumptions
New data now emerging indicates that some of the assumptions incorporated into
MOBILESa may warrant reconsideration in the future. Some of these assumptions, if changed,
could significantly change the resulting emission estimates under some scenarios. Directionally,
the effect of some such changes would be to increase projected emissions and the effect of other
changes would be to reduce them. EPA is not prepared to recommend any changes to the
MOBILESa model at this time. However, it is useful to examine where some such changes could
A - 2
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be considered in the future and what the effect on emissions might be. These areas of potential
reconsideration fall into several categories.
Improved Evaporative System Effect
Recent data indicates there may be room for improvement in the way MOBILES a models
evaporative emissions. EPA is especially interested in examining the implications of new data
in three areas of evaporative emissions projection: resting losses, leaking fuel during diurnals, and
hot soak emissions.
Resting losses occur continuously in liquid fuel vehicles due to permeation of fuel through
fuel system components and from evaporative canisters. Recent testing performed at constant
temperatures on fuel-injected vehicles with closed-bottom canisters indicates that resting losses
may be as much as 5 times higher than the estimates currently used in MOBILESa. If further
testing and analysis bear out the validity of this data, evaporative emission estimates could
increase by about 0.1 to 0.2 g/mi in a Year 2020 evaluation, or about a 50 to 100 percent
increase in evaporative emissions. Another related concern, about which data is not currently
available, is the effect of slow fuel leaks which are not detected by I/M (and possibly not by
recall testing) and yet which could contribute significantly to ambient hydrocarbon emissions.
EPA will continue to explore this area as well.
Very little data exists regarding resting losses on alternative fueled vehicles. EPA expects
that neat alcohol fuels may have permeation losses, but their magnitude may be less than for
gasoline (or mixed gasoline fuels) because of the lower fuel volatility. Also, neat alcohol
vehicles may not require very large evaporative canisters, which we believe to be a significant
source of resting loss emissions on many vehicles. Gaseous fuel vehicles, because of their
closed, pressurized fuel systems, are expected to have very low resting loss emissions.
Another potential source of evaporative emissions not currently modeled is fuel line or
vapor line leaks during diurnal heating of the vehicle. "Weeping" of liquid fuel from aging or
damaged lines may be a significant source; 5 percent of vehicles emitting 10 grams during a
diurnal could represent up to 0.05 g/mi of additional evaporative emissions. EPA currently plans
to conduct a testing program which will examine this issue further.
The third area under consideration by EPA at this time is the modeling of hot soak
emissions. Recent data collected on in-use vehicles inexplicably indicates significantly higher
hot soak emissions than earlier testing. If this recent data proves to be more representative of
the in-use fleet than earlier data, the effect on modeled emissions would be as much as 0.21 g/mi,
or about a doubling of projected evaporative emissions after improved evaporative systems are
hi place..
Inspecti,on/Mflfotenance Effect
EPA is also reassessing how MOBILESa models the effect of I/M programs on exhaust
and evaporative emissions. For exhaust emissions, Enhanced I/M programs are modeled by
reducing estimated no-I/M emissions using a curve predicting after-repair versus before-repair
A - 3
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emissions levels. Preliminary analyses indicate that estimates of after-repair emission levels and
the loss of benefits between inspections potentially might be improved.
The effect of Enhanced on evaporative emissions is based on the observed emissions of
vehicles passing or failing the pressure and purge tests in the I/M program. In this case, failed
vehicles which are repaired are assumed to return to the emission level of the average of passing
vehicles. An argument can be made that as the vehicle ages, the post-repair emissions should
be expected to be somewhat higher than the average of passing vehicles. For example, a repair
could consist of replacing or reconnecting of a purge line, and the vehicle could once again pass
the purge test. However, if the canister had become so saturated as to be impaired in capacity
even after the purge line is repaired, emissions could remain high without being detected by I/M
pressure/purge tests. EPA will further consider this issue as more data on evaporative repair
effectiveness becomes available. In addition, EPA is examining whether assumptions about other
parameters affecting evaporative emissions modeling may need to be improved in light of
emerging data.
Effect of Fuel: RFG1. RFG2. CA RFG
MOBILESa incorporates estimates for the exhaust reduction (from Clean Air Act baseline
gasoline) and RVP that would result from the use of federal Phase 2 reformulated gasoline. The
model uses a 20 percent reduction in exhaust emissions and an RVP of 7.5. The current estimate
of the effect of California reformulated gasoline (as described above) is a 29. percent exhaust
reduction and an RVP of 6.9.
More recent analysis indicates that the exhaust reductions for federal Phase 2 reformulated
gasoline may be less than assumed in MOBILESa and that the expected RVP could also be
lower. Thus the exhaust benefit may be modeled in the future to be smaller; the evaporative
emission reduction would be greater. Recent EPA estimates for California reformulated gasoline
based on the latest data indicate only a 22 percent reduction in exhaust emissions.
Special Considerations for Certain Alternative Fueled Vehicles
The assumptions built into MOBILESa about the effectiveness of I/M programs were
developed for gasoline vehicles. EPA believes that absent changes that are not currently planned,
I/M programs may in effect be more stringent for vehicles operating on alternative fuels than for
gasoline vehicles. The primary issue is that current CNG vehicles, operating as they do on fuel
that is largely methane, have much higher methane emissions than gasoline (or other alternative
fuel) vehicles. Certification for CNG vehicles, as proposed in EPA's current Gaseous Fuels
rulemaking, would be based on non-methane emissions (non-methane hydrocarbons (NMHC) or
non-methane organic gases (NMOG)), with no requirement for the measurement of methane.
However, I/M programs as currently planned do not distinguish methane from other HC
emissions. This means that a vehicle with rather high total HC emissions may easily pass
certification for NMHC or NMOG but find it difficult to pass a total HC test in an I/M program
difficult. The situation could be made more difficult by the fact that I/M test equipment,
calibrated for propane gas as a typical hydrocarbon, tends to read higher methane emissions than
actually exist.
A - 4
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Beyond the specific case of CNG vehicles and methane, another effect may exist for other
alternative gaseous or alcohol fuels. Vehicles certified as LEVs, ULEVs, or ILEVs are subject
to standards expressed in terms of NMOG, an approach that adjusts exhaust emissions based on
the tendency of the emission components to form ozone. For gasoline vehicles, emissions of
NMOG very closely match NMHC emissions. However, for non-petroleum fuels, NMOG and
NMHC can be significantly different for the same vehicle. Currently planned I/M programs do
not account for ozone reactivity and measure only total HC emissions. Because of this, it is
possible that I/M programs, particularly Enhanced or Max I/M programs as they are currently
conceived, might effectively be more stringent for alternative fueled vehicles than for gasoline
vehicles certified to the same standards. This is because the HC as measured in the I/M program
may be greater than the NMOG measured during vehicle certification, even if methane emissions
were accounted for. EPA will further examine whether differences in NMOG and NMHC might
warrant different I/M credits in the modeling of some or all alternative fuel vehicles.
EPA believes that this effect may result in a greater effective stringency for CNG vehicles
than for gasoline vehicles under currently-planned Enhanced I/M programs. Assuming the same
distribution of in-use emissions as for gasoline vehicles, the greater effective stringency would
result in a greater number of I/M failures and subsequent repairs. The emission improvements
resulting from these repairs could be expected to result in lower average emissions for the overall
fleet of CNG vehicles. EPA is considering how this effect might be incorporated into the
modeling of CNG vehicles.
Special Considerations for Fleet Vehicles
To date, EPA analysis of the emission reductions of fleet vehicles treats fleet vehicles in
the same manner as general-use vehicles. To the extent that evidence of special operational
patterns which significantly affect emissions become available, EPA would support incorporating
these effects into its modeling.
Two areas in which the experience of fleet vehicles may be different from other vehicles
are being examined by EPA. First, fleet vehicles capable of operating on gasoline as well as on
an alternative fuel may tend to be operated on gasoline alone after they leave fleet service. There
is currently little evidence to confirm whether this will occur, or indeed whether such vehicles
will be introduced into fleet service in substantial numbers. The second area where fleet
experience may differ from general vehicles is in the rate at which they are purchased for
replacement. We expect that the resale market for fleet vehicles capable of operating on gasoline
will be similar to the current resale market for gasoline fleet vehicles. Thus we would expect
that the turnover rate for these vehicles will be similar, with fleets on average replacing their
vehicles about every three years. However, for dedicated alternative fueled fleet vehicles, resale
will be more of a problem until broad alternative fuel infrastructure is in place. Therefore,
dedicated alternative fueled fleet vehicles, including ILEVs, may remain in fleet service for their
entire life. This pattern may result in a smaller number of dedicated vehicles. If this difference
in treatment by fleets becomes a reality, then it may be necessary to model gasoline and gasoline-
capable fleet vehicles differently from dedicated alternative fueled vehicles and ELEVs.
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EPA is not prepared to recommend special treatment of fleet vehicles in emissions
modeling at this time. However, such changes will be warranted if future data confirms the
presence of effects such as those discussed above.
A - 6
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Appendix B
Lifetime NMHC Emission Factors (g/mi)
Light-Duty Clean-Fuel Fleet Vehicles
Tier 1 Exhaust/
Improved Evap.
Cert, on indolent, operated on:
Baseline Gasoline
Federal RFG 2
CARFG
Enhanced I/M
exhaust
0.713
0.597
0.508
vapor
0.230
0.153
0.119
Max I/M
exhaust
0.327
0.274
0.233
vapor
0.230
0.153
0.118
B - 1
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Appendix C
Enhanced I/M MOBILESa Input File
i
i
i
i
i
2
1
8
3
1
1
3
1
1
2
2
96
83
96
96
98
4
PROMPT - Prompt for LEVIMP file (*.d)
Enhanced I/M.
TAMFLG
SPDFLG
VMFLAG
MYMRFG
NEWFLG
IMFLAG — One I/M program
ALHFLG
Enter ATP, Pressure, and Purge data.
Onboard Refueling Vapor Recovery.
LAP record appears once for each scenario.
ATPFLG
RLFLAG
LOCFLG
TEMFLG
OUTFMT
PRTFLG
IDLFLG
NMHFLG
HCFLAG
20 86 20 03 03 096
81 20 2221 11 096.
83 20 2221 11 096.
86 20 2221 11 096.
2222
20 19.6 81.6 20.6 27.3 20.6 07
112-column descriptive format.
HC exhaust only.
1-THC, 2-NMHC, 3-VOC, 4-TOG, 5-NMOG.
Print sum and component emissions.
1 1 2221
12211111
4211 0.80 20.0 2.00
94 1
Baseline Fuel.
4 20 19.6 81.6
94 1
Indolene Fuel
4 20 19.6 81.6
94 1
Fed Phase
4 20 19.6
94 1
Fed Ph2
4 20 19.6
94 1
CA RFG
. C 71.6 91.6 10.5
20.6 27.3 20.6 07
C 71.6 91.6 09.0
20.6 27.3 20.6 07
1 Fuel C 71.6 91.6 10.5
81.6 20.6 27.3 20.6 07
C 71.6 91.6 10.5
81.6 20.6 27.3 20.6 07
08.7 92 1 1 1
09.0 92 1 1 1 2
08.0 92 1 1 3
07.5 92 1 1 2
(Vapor)
C 71.6 91.6 10.5 06.9 92 1 1 1
IM240 Program
ATP
Pressure
Purge
Onboard VRS
Scenario description record
LEV program parameter red.
Local Area Parameter record
Scenario description record
LEV program parameter red.
Local Area Parameter record
Scenario description record
LEV program parameter red.
Local Area Parameter record
Scenario description record
LEV program parameter red.
Local Area Parameter record
Scenario description record
LEV program parameter red.
Local Area Parameter record
C - 1
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Maximum I/M MOBILESa Input File--(for Tier 1 Vehicles)
Max I/M.
i
i
i
4
1
8
3
1
1
3
1
1
2
2
96
83
96
PROMPT - Prompt for LEVIMP file (*.d)
TAMFLG
SPDFLG
VMFLAG
MYMRFG
NEMFLG
IMFLAG - Max I/M for Tier 1.
ALHFLG
ATPFLG — Enter ATP, Pressure, and Purge data.
RLFLAG — Onboard Refueling Vapor Recovery.
LOCFLG — LAP record appears once for each scenario.
TEMFLG
OUTFMT - 112-column descriptive format.
PRTFLG - HC exhaust only.
IDLFLG
NMHFLG - 1-THC, 2-NMHC, 3-VOC, 4-TOG, 5-NMOG.
HCFLAG - Print sum and component emissions.
1 1 2221
12211111
4211 0.80 20.0 -2.00
20 86 20 03 03 096
81 20 2221 11 096.
83 20 2221 11 096.
96 86 20 2221 11 096.
98 2222
4 20 19.6 81.6 20.6 27.3 20.6 07
94 1
Baseline Fuel.
4 20 19.6 81.6 20.6 27.3
94 1
Indolene Fuel
4 20 19.6 81.6
94 1
1 Fuel C 71.6 91.6 10.5 08.0 92 1 1 3
81.6 20.6 27.3 20.6 07
91.6 10.5
20.6 07
C 71.6 91.6 09.0
20.6 27.3 20.6 07
08.7 92 1 1 1
09.0 92 1 1 1 2
Fed Phase
4 20 19.6
94 1
Fed Ph2
4 20 19.6 81.6
94 1
CA RFG (Vapor)
C 71.6 91.6 10.5
20.6 27.3 20.6 07
07.5 92 1 1 2
C 71.6 91.6 10.5 06.9 92 1 1 1
IM240 Program
ATP
Pressure
Purge
Onboard VRS
Scenario description record
LEV program parameter red.
Local Area Parameter record
Scenario description record
LEV program parameter red.
Local Area Parameter record
Scenario description record
LEV program parameter red.
Local Area Parameter record
Scenario description record
LEV program parameter red.
Local Area Parameter record
Scenario description record
LEV program parameter red.
Local Area Parameter record
C - 2
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Maximum I/M MOBILESa Input File (for LEVs, ILEVs & ULEVs)
Max I/M.
1
1
1
1
1
2
1
8
3
1
1
3
1
1
2
PROMPT - Prompt for LEVIMP file (*-d)
TAMFLG
SPDFLG
VMFLAG
MYMRFG
NEWFLG
IMFLAG - One I/M program
ALHFLG
ATPFLG — Enter ATP, Pressure, and Purge data.
RIiFLAG — Onboard Refueling Vapor Recovery.
LOCFLG — LAP record appears once for each scenario.
TEMFLG
OUTFMT - 112-column descriptive format.
PRTFLG - HC exhaust only.
IDLFLG
NMHFLG - 1-THC, 2-NMHC, 3-VOC, 4-TOG, 5-NMOG.
HCFLAG - Print sum and component emissions.
2
96 20 86 20 03 03 096 1 1 2221
83 81 20 2221 11 096. 12211111
96 83 20 2221 11 096.
96 86 20 2221 11 096.
98 2222
3 20 19.6 81.6 20.6 27.3 20.6 07
Baseline Fuel... C 71.6 91.6 10.5 08.7
3 20 19.6 81.6 20.6 27.3 20.6 07
Indolene Fuel C 71.6 91.6 09.0
3 20 19.6 81.6 20.6 27.3 20.6 07
Fed Phase 1 Fuel C 71.6 91.6 10.5
3 20 19.6 81.6 20.6 27.3 20.6 07
Fed Ph2 C 71.6 91.6 10.5
3 20 19.6 81.6 20.6 27.3 20.6 07
4211 0.80 20.0 2.00
92 1 1 1
09.0 92 1 1 1 2
08.0 92 1 1 3
07.5 92 1 1 2
CA RFG (Vapor)
C 71.6 91.6 10.5 06.9 92 1 1 1
IM240 Program
ATP
Pressure
Purge
Onboard VRS
Scenario description record
Local Area Parameter record
Scenario description record
Local Area Parameter record
Scenario description record
Local Area Parameter record
Scenario description record
Local Area Parameter record
Scenario description record
Local Area Parameter record
C - 3
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Fact Sheet
Lifetime Emissions for Clean Fuel Vehicles: Interim Values
The attached table presents interim values for lifetime emission factors for several types of light-
duty Clean Fuel Vehicles (CFVs). These interim factors are presented in response to recent
requests for additional numbers not presented in the EPA Technical Report titled "Lifetime
Emissions for Clean Fuel Fleet Vehicles" (October, 1993). The values presented in this table
result from identical MOBILE 5a modeling runs and fuel adjustment factors as those used in the
Lifetime Emissions report. As in that report, this table results from the simulation of the average
emission of vehicles throughout their lives. Thus, the "lifetime emission factors" incorporate into
a single average emission factor both the cleaner in-use operation in the early years of a vehicle's
life and the relatively dirty operation as the vehicle ages. These factors are appropriate for use
in estimating the relative in-use emissions of groups of vehicles which meet the respective CFV
emission standards.
The MOBILE 5a emission factors which are appropriate to apply depend on the stringency of a
state's in-use motor vehicle program (such as inspection and maintenance and auditing
programs). The values in the attached table assume a state does not have in place the full set
of programs required for lower emission factors to be claimed. For states which have (1) periodic
IM240 testing with specific outpoints, (2) automated onboard diagnostics system checks, and (3)
SIP provisions for auditing and corrections, emissions factors will be lower than the ones
presented here.
In the Lifetime Emissions report, the modeling results were in one case applied incorrectly.
Specifically, values presented for scenarios involving certification and operation on the same fuel
(i.e., California Phase 2 and federal Phase 2 reformulated gasolines (RFG) and other fuels)
actually apply to another scenario (certification on Indolene and operation on California Phase 2
RFG). The correct values appear in the attached table. Another change is that since under the
recently issued Clean Fuel Fleet final rule there is no provision for certification test fuel which
meets federal RFG specifications (instead, test fuel for CFV certification must be either California
Phase 2 RFG or conventional federal test fuel ("Indolene")). Thus, the scenario in the Lifetime
Emissions report for certification (and operation) on federal RFG does not appear in the attached
table.
These interim numbers will be updated in the near future once the new version of the MOBILE
model is released (MOBILE 5b). At that time, values for light-duty trucks will also be added.
Please direct questions to Tad Wysor, Senior Engineering Project Manager, U.S. EPA Office of
Mobile Sources, at (313) 668-4332.
August 24, 1994
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Interim Lifetime Emissions Factors (g/ml)
Light Duty Vehicles (LDV)
Tier 1
Cartifiod On:
Indolene
Indolene
Indolene
Indolene
Other Fuel
Op*r«t«d On:
Baseline
Fed RFG 1
Fed RFG 2
CA RFG 2
Same Fuel
NMHC
Exhaust
0.25 g/mi
0.713
0.646
0.597
0.508
0.621
HC
Vapor
0.230
0.184
0.153
0.119
0.119-0.230
CO
3.4 g/ml
10.596
10.596
10.596
10.596
10.205
NOx
0.4 g/ml
0.935
0.935
0.935
0.935
0.810
CFV/LEV
Certified On:
Indolene
Indolene
Indolene
Indolene
CA RFG 2
Other Fuel
Operated On:
Baseline
Fed RFG 1
Fed RFG 2
CA RFG 2
CA RFG 2
Same Fuel
NMHC
Exhaust
0.075 g/ml
0.601
0.544
0.504
0.429
0.526
0.526
HC
Vapor
0.230
0.184
0.153
0.119
0.119
0.119-0.230
CO
3.4 g/mi
8.923
8.923
8.923
8.923
8.595
8.595
NOx
0.2 g/ml
0.829
0.829
0.829
0.829
0.718
0.718
CFV/ULEV
Certified On:
Indolene
Indolene
Indolene
Indolene
CA RFG 2
Other Fuel
Operated On:
Baseline
Fed RFG 1
Fed RFG 2
CA RFG 2
CA RFG 2
Same Fuel
NMHC
Exhaust
0.04 g/ml
0.571
0.517
0.478
0.407
0.500
0.500
HC
Vapor
0.230
0.184
0.153
0.119
0.119
0.119-0.230
CO
1.7 g/ml
8.923
8.923
8.923
8.923
8.595
8.595
NOx
0.2 g/mi
0.829
0.829
0.829
0.829
0.718
0.718
CFV/ILEV
Certified On:
Any Fuel
Operated On:
Same Fuel
NMHC
Exhaust
0.075 g/mi
0.526
HC
Vapor
0.0
CO
3.4 g/ml
8.595
NOx
0.2 g/mi
0.718
Tad Wyaor, OS EPA, Offloe of Mobil* Source*, 313 668-4332
Auguat 25, 1994
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