-R-13-0.16-
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GUIDANCE FOR
EMISSION REDUCTION CREDIT GENERATION
BY CLEAN FUEL FLEETS & VEHICLES
Unit«d States Bnvironm«ntal Protection Agency
January, 1993
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Guidance for
Emission Reduction Credit Generation
by Clean Fuel Fleets & Vehicle*
I. Foreword
The Clean Air Act, as amended in 1990, mandates market-based
approaches in certain Federal programs and encourages the use of •
such approaches at the Federal, State, and local levels, as well as
by individual sources, to facilitate the attainment of the mandated
milestones and goals of Title I of the Clean Air Act Amendments.
In response to the Act, the Agency has proposed and issued rules
and guidance that incorporate the use of market-based measures in
Federal program areas such as acid rain reduction and clean fuel
fleet vehicle purchases.
To facilitate the development of market-based programs that go
beyond such Federal programs, the Agency is developing
comprehensive rules and guidance for States and individual sources
to follow in designing and adopting market-based programs in State
Implementation Plans (SIP's). The pending Economic Incentive
Program (EIP) Rules draw upon the general principles found in the
1986 Emission Trading Policy Statement (see 51 FR 43631 December 4,
1986) while providing a broad framework for the development and use
of a wide variety of market-based control strategies. For States
to take credit in their SIP's for emission reductions based upon
such strategies, reductions must be quantifiable, enforceable,
surplus to other Federal and State requirements, permanent within
the timeframe specified by the program, and consistent with all
other statutory and Federal regulatory requirements. The proposed
EIP Rules are applicable to all types of sources including
stationary and mobile sources and define general regulatory
elements (e.g., program baseline, auditing procedures, enforcement
requirements) that should be included in the design of market-based
control strategies.
In addition to these broadly applicable general rules, the
Agency is also developing a more narrowly focused document entitled
"Guidance on the Generation of Mobile Source Emission Reduction
Credits" specifically for the development of market-based programs
involving tit* use of emission reduction credits generated by mobile
sources. Such mobile source emission reduction credits (MERC's)
can be generated from surplus emission reductions over and above
Federal mobile source program requirements and can potentially be
used to substitute for stationary emission reduction requirements.
The general guidance on the generation of MERC's mentioned above
addresses issues unique to emission reduction credits generated by
mobile sources, including the calculation of emissions baselines
for participating sources, the projection of future emissions
levels, and the time-averaging of emission reduction credits that
vary over time.
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To exemplify how MERC'a can be generated from a specific
category of mobile sources, the following guidance addresses clean
fuel vehicles and fleets, and illustrates how surplus purchases
(i.e., beyond Federal program requirements) can be used to generate
emission credits in a mobile-stationary source trading program.
While market-based mobile source programs must be consistent with
the Economic Incentive Program Rules and the Guidance on the
Generation of Mobile Source Emission Reduction Credits, EPA does
not intend to limit flexibility and innovation beyond the
requirements found in these documents. The following guidance is
intended to assist in the design of a Clean Fuel Vehicle and Fleet
credit generation program, not to limit state initiative,
creativity, or flexibility in developing a program which best meets
the state's needs within the limits of good environmental policy.
IX. Introduction
Section 246 of the 1990 Clean Air Act Amendments (the Act)
requires states which contain serious, severe, or extreme ozone
nonattainment areas or areas with carbon monoxide design value
greater than 16 ppm to revise their State Implementation Plans
(SIPs) to establish a clean fuel fleet program. At present, the
areas to be covered by the program include 22 nonattainment areas
in 19 states (see attached table 1). The purchase requirements of
the program, as prescribed in the Act, will begin in 1998 and will
apply to those fleets which operate in a covered area and which
contain any combination of 10 or more covered light-duty vehicles
(LDV), light-duty trucks (LDT), or light- or medium-heavy-duty
vehicles (HDVs). More states/areas could be added to the program
In the future if they are found to be in any of the ozone
noncompliance categories outlined above. According to the Act, the
fleet programs must also include provisions to implement a purchase
credit program for additional, early, and/or cleaner vehicle
acquisitions. Affected states may independently choose to expand
the program to additional fleets or to expand the programs
statewide. States not covered by the program may opt-in to this
program or develop similar programs voluntarily, as already has
been done by several states. This is especially the case in those
70 areas which have some degree of ozone air quality problem and
are covered under the fleet provisions of the recently enacted
National Energy Policy Act but are not covered by the clean fuel
fleet provisions of the Clean Air Act Amendments.
It has been proposed that emission credits generated by
vehicles under a clean fuel fleet program would also be usable as
emission reduction credits in an emission credit trading program
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tinder the Economic Incentive Program1. These credits could then
£e generated, traded, and applied toward emission reduction
requirements of another source under various state and federal
programs.
The purpose of this document is to provide technical guidance
to states that are interested in allowing credits generated in
their clean fuel vehicle fleet program or a similar state-
oriainated program to be used for emission credit trading. State-
originated programs to grant these credits may be substantially
different than the federal fleet program. EPA believes these
trading programs should be designed not only to permit cross-source
credit trading, but also to enhance an objective of the fleet
program: encouraging the purchase< of clean fuel vehicles that
offer long-term environmental benefits.
This document is organized as follows. Sectipn II briefly
describes the clean fuel fleet credit program as described in the
Act and in the regulations proposed by EPA2. Section III describes
certain elements which EPA believes should be included in a program
that allows fleet emission credits to be traded. Section IV
proposes a method for calculating the emission credits. Section V
addresses problems that may occur in such-a trading program and
proposes some solutions that states may consider to resolve those
problems. Finally, section VI discusses the administration of the
credit program.
III. The Clean Fuel Fleet Purchase Vehicle Credit Program
The 1990 Clean Air Act Amendments contain specific
requirements for the clean fuel fleet program ("fleet program")
that affected states must adopt. Under the provisions of the Act,
a specific portion of the new vehicles purchased by certain fleet
owners will be required to meet clean fuel vehicle • emission
standards.
According to the Act, purchase credits can be generated
through purchase of: (1) more clean fuel vehicles than required to
fulfill the purchase requirements under.the program, (2) clean fuel
vehicles that meet more stringent emission standards than r^"«d
(Ultra Low Emission Vehicle (ULEV) or Zero Emission Vehicle (ZEV)
standards),. (3) clean fuel vehicles in exempted categories (i.e.,
heavy nea^r-duty vehicles (>26000 Ibs GVWR), rental vehicles,
emergency Chicles, law enforcement vehicles, or nonroad vehicles) ,
or (4) clean fuel vehicles purchased before the effective date of
the fleet program. EPA has proposed that each state can decide the
1 See Notice of Proposed Rulemaking, Economic Incentive
Program Rule7, 40 CFR Part 51, due to be published in the Federal
Register by November 15, 1992.
2 see Notice of Proposed Rulemaking, 56 FR 50196 (October
3, 1991). - '
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size, type, and location of fleets eligible to generate purchase
credits under the fleet program. At a minimum, however, all fleet
operators subject to the compliance requirements of the fleet
program are eligible to generate fleet purchase credits.
Under the fleet program, these purchase credits can be used in
two ways. First, they may be used by the fleet owner who generated
them to demonstrate compliance with the fleet program purchase
requirements in a subsequent year. Second, they may be traded or
sold for use by another fleet owner to demonstrate compliance with
the fleet purchase requirements, as long as the trade occurs within
the same nonattainment area. Purchase credits generated under the
fleet program can be held for use at a later time without
depreciation. However, purchase credits generated under the
program can be traded only for purchases of vehicles in the same
class (heavy-duty or light-duty). Also, credits are to be adjusted
to reflect the level of emission reduction achieved by the vehicle
so that the credit earned in purchasing an extra-clean vehicle (a
ULEV or a ZEV) reflects its extra emission reduction benefit as
compared to a clean fuel vehicle.
The fleet program also includes a new federal program to
provide special incentives in the form of expanded Transportation
Control Measure (TCM) exemptions for the purchase of Inherently Low
Emission Vehicles (ILEVs) also known as Clean Air Vehicles (CAVs).
ILEVs are clean fuel vehicles (must meet LEV requirements and the
ULEV NOx standard) which also have very low evaporative emissions
relative to their conventional fuel counterparts even when the
control system is disabled. These vehicles can be purchased as
part of the fleet program for either compliance or credit purposes,
with the owner gaining the additional incentives (e.g., HOV lane
exemptions) for the vehicles involved3.
While the above criteria are useful for creating a vehicle
purchase credit program under the auspices of the fleet program,
they are insufficient for defining a broader emission reduction
credit program, where the focus is on the mass of emission
reductions rather than the number of vehicles purchased. The fleet
purchase credit program needs to be converted into a fleet emission
reduction credit program. This is discussed below.
rv.
Credit Generation Program Elements
In general, credits for trading will be generated in ways
similar to those specified in the fleet credit program. However,
several additional elements are necessary in order to permit
calculating credit values for the transfers, to ensure consistency
These additional incentives are discussed in the NPRM
Clean Fuel Fleet Credit Programs, Transportation Control Measure
Exemptions, and Related Provisions" (56 FR 50196, October 3, 1991)
and include, among other things, expanded transportation control
measure exemptions for ILEVs.
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with the general guidelines of the fleet program, and to ensure
that the credit reflects true emission reductions. Suggested
elements for a program that would convert clean fuel vehicle
credits to tradeable emission reduction credits are described
below. It will be up to the states to develop a proposal to
integrate these general elements into a specific trading program.
Element 1. Credit-generating vehicles must be in addition to
those required to be purchased by statute or must
be certified to cleaner standards.
This element is necessary to ensure that credits are surplus:
they reflect additional emission savings through the purchase of
more clean fuel vehicles or cleaner vehicles than are otherwise
required.
Element 2. Clean fuel vehicles may operate on alternative
clean fuels or on petroleum-based clean fuels such
as reformulated fuels.
Since the focus of this program is on expanding the use of
clean fuel vehicles to generate emission reduction credits, it is
not necessary to require that the affected vehicles run on any
particular clean fuel. It is only necessary that the vehicles meet
the clean fuel vehicle emission standards. At the same time, it
should be noted that vehicles which run on clean alternative fuels
(e.g., electricity, gaseous fuels, and neat alcohol) will
potentially generate more emission credits than those that run on
reformulated fuels, since they tend to be inherently lower
emitting.
Element 3. Vehicles need not be dedicated fuel vehicles to
generate exhaust emission credits. However, only
dedicated fuel vehicles such as ILBVs may generate
credits based on vapor emission reductions.
In a broad sense, EPA is not averse to including dual-fuel,
flexible-fuel, or hybrid electric vehicles in a program to generate
credits using exhaust emission reductions. However, including
these vehicles complicates the calculation of tradeable credits.
This.. _is because it is necessary to verify how many miles the
vehicle operated meeting the clean fuel vehicle standards as
opposed to conventional standards. Special adjustments may be
needed for hybrid vehicles as well as for vehicles meeting
different clean fuel vehicle standards on different fuels.
Therefore, any program that includes dual-fuel, flexible-fuel,
or hybrid electric vehicles must include a provision to ensure that
vehicle miles traveled on the different fuels or using an auxilary
power plant can be calculated reliably. This will ensure that the
calculation of the credit accurately reflects the actual reduction
in emissions from operation on each fuel or in each mode. One way
to improve accurate reporting is by equipping these vehicles with
"fuel keys," which act to track, by computer, the fuel type
dispensed to each vehicle. Such a system can be expanded to permit
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coding of appropriate mileage records, to enable accurate
calculation of vehicle miles traveled on each fuel. Chronometers
may also be useful in assessing the operation of auxilary power
plants. This, and other methods, are currently being explored by
some fleet owners. Fuel receipts may also be needed as well.
Systems which do not rely on human factors are preferable.
Exhaust emission credits will only be issued for vehicles
meeting at least the clean fuel vehicle emission standards of
sections 243 and 245 of the 1990 Clean Air Act Amendments.
Vehicles beating the conventional standards but not meeting clean
fuel standards cannot receive credits. In the case of dual-fuel,
flexible fuel, or hybrid electric vehicles, credits can be
generated only for the portion of operation when the vehicle meets
the clean fuel standards. Clean fuel vehicles meeting different
sets of clean fuel standards on different fuels or in different
modes will receive credits in proportion to their use.
Conventional flexible-fuel vehicles (vehicles that operate on two
conventional fuels but do not ever meet the clean fuel vehicle
emission standards) will not be allowed to participate in this
program.
The generation of emission reduction credits based on a
reduction in vapor emissions must be limited to dedicated fuel
vehicles such as ILEVs. For dual-fuel and hybrid electric
vehicles vapor emissions may occur whether the vehicle is operating
on conventional or clean fuels. In fact, these vehicles could
potentially have even higher vapor emissions than their
conventional-fueled counterparts if the vapor canister is not
purged when the clean fuel is being used.
Element 4. Vehicles can be new or converted.
The clean fuel vehicle fleet program allows converted vehicles
to be counted as vehicle purchases for purposes of compliance.
Converted vehicles will also be permitted in this credit generation
program. Conversions must be certified in accordance with the
provisions of the fleet program and meet the appropriate emission
standards. The conversion may be to a dual or dedicated clean fuel
vehicle configuration. However, as noted above, credits are only
available when the vehicle is operating on a fuel or in a mode
which permits it to meet the clean fuel vehicle emission standards.
Element. 5. Vehicles must pass an annual I/M test in areas that
require testing and where I/M tests are available.
This element is needed to ensure that the vehicle is running
correctly in use. Vehicles for which the owner sought a waiver
from repair may not generate credits. In areas that do not require
I/M testing, EPA will not require that vehicles in the program be
tested annually. Instead, EPA and the states will rely on results
obtained from national I/M tests to determine if the vehicles in
the credit program are actually running correctly. In this case,
if there is evidence from national vehicle testing that a
particular vehicle model is not meeting requirements for the LEV
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program standards of interest, it is consistent with other EPA
enforcement programs to assume that similar vehicles in areas that
do not have I/M testing are also not meeting the standards, and to
require those vehicles to be serviced accordingly. Alternatively,
credit discounting may be an option to account fpr uncertainty or
to address problems identified.
Element 6. Credits will be calculated yearly, preferably on a
calendar year basis.
Ideally, the credit generation programs should coincide on a
time period basis. However, fleet purchase credits are generated
on a model year basis while in most cases fleet emission reduction
credits would be used on a calendar year basis. Given the methods
used to calculate the fleet credits discussed below and the fact
that compliance determinations for other programs are annual, EPA
believes that credits generated by vehicles in the fleet emission
reduction program should be calculated annually, preferably on a
calendar year basis. Therefore, for the purpose of calculating
credits for this program, vehicle miles traveled will be measured
from January 1 through December 31 of each year, and credits will
be generated for that period. Other annual periods would probably
be acceptable depending on state preference.
Element 7. Vehicles used in the fleet credit program cannot be
used in the fleet emission reduction credit
program, and vie* versa.
This element is necessary because, as noted above, the credits
generated in the fleet purchase program are one-time, per-vehicle
credits that are used to offset annual purchase requirements, while
the credits generated in the emission reduction program for trading
are used to offset tons of emissions generated by other sources.
In the fleet program, vehicles are counted only once, to fulfill
one annual purchase requirement, and credits generated are traded
against other annual vehicle purchase requirements. In the
emission credit program, however, reductions in vehicle emissions
due to the use of a clean fuel vehicle are in addition to those
generated by vehicles acquired to meet the purchase requirements.
Therefore, it ia necessary to segregate these vehicles for credit
accounting purposes to ensure that double-counting does not occur.
At the same time, in the case where a credit is being
generated by the purchase of a cleaner vehicle, the actual purchase
of the clean vehicle will be counted as satisfying the purchase
requirement under the fleet program, while the added emission
benefits from the cleaner characteristics of the vehicle (ULEV,
ZEV) could generate a credit. However, as noted above, the
reduction in emissions due to the cleaner nature of the vehicle can
generate credits in only one of the programs: either the fleet
purchase program or the fleet emission reduction program. Due to
administrative difficulties, it is probably not advisable to split
these "cleaner" credits between programs. An individual ULEV or
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ZEV could be used to generate either purchase credits or emission
reduction credits but not both.
Element 8. Credits are to be calculated on a per pollutant
basis.
The program described in this document focuses on reductions
in emissions of pollutants for which clean fuel vehicle standards
apply: non-methane organic gas (NMOG), carbon monoxide (CO), and
oxides of nitrogen (NOx). No credits will be given for
formaldehyde (ECHO) or particulate matter (PM). In the case of
formaldehyde, there is no standard for this substance for
conventional vehicles/ so there is no rate to use in the formula
for calculating the credit described below. EPA believes that
using average formaldehyde emission levels as a base is
inappropriate since this substance is not regulated for most
vehicle/fuel groups and relatively more credits would be allocated
than if it were currently regulated. In the case of PM, the
emission rate for most conventional vehicles (gasoline) is so close
to zero now, that allowing credits for clean fuel vehicles using
the diesel cycle PM standard would amount to a large "give away" of
PM credits.
NMOG credit values derived from the clean fuel vehicle exhaust
emission standards are not directly interchangeable with other
hydrocarbon values needed for trading to other sources. NMOG
credits must be converted to NMHC or THC, as appropriate for each
vehicle/fuel.
Element 9. Credit* can be generated only by those vehicles
allowed to generate credits in the fleet program as
determined by the states.
Although any clean fuel vehicle could feasibly generate
exhaust emissions credits that could be traded, EPA recognizes the
practical problems that would be associated with allowing any and
all vehicle owners to participate in this program. Specifically,
it would be difficult for states to enforce the program if credit
generating vehicles are spread among too many vehicle owners.
Therefore, as noted above, it will be up to the states to decide
who is eligible to generate credits in the fleet emission reduction
program, based on their decision for participation eligibility in
£he fleet program or perhaps additional criteria if the federal
Clean Fuel Fleet Program does not apply in their state. However,
as a minimum, fleets covered by the Clean Fuel Fleet Program under
section 246 must be permitted to participate.
Element 10. Vehicle owners may be limited to either TCM
exemptions or tradeable credits for the same
emission reductions.
Under section 246 of the Clean Air Act, fleet owners can get
both purchase credits and -TCM exemptions for the same qualifying
vehicle. However, if concerns exist about double incentives,
vehicle owners could be limited to either TCM exemptions "or
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tradeable emission credits for the same qualifying emission
reduction.
There are two situations where this could be applied. First,
for fleets/vehicles covered by the state's section 246 fleet
program, early and extra vehicles could get either purchase credits
or tradeable emission credits. As was mentioned above, such
vehicles would retain their eligibility for TCM exemptions if they
are used for purchase credits under the fleet program. However, if
such vehicles use their emission reductions for tradeable credits
under this program the vehicle would be considered out of the fleet
program and no longer eligible for TCM exemptions. Second, clean
fuel vehicles in non-covered fleets to which the state may choose
to provide some form of TCM exemptions or other incentives should
not receive such exemptions/ incentives for emission reductions and
then be able to trade away such emission reductions. Thus, these
vehicles would be eligible for exemptions/incentives or tradeable
emission credits but not both.
More specifically, additional (early, extra) clean'fuel fleet
vehicles cannot get temporal TCM exemptions and also trade away the
qualifying exhaust emission reductions. Similarly, ILEVs cannot
get expanded TCM exemptions and trade away the reduced vapor
emissions.
However, a splitting of benefits is possible. Vehicles
certified as ULEVs or ZEVs under 40 CFR Part 88 could trade away
the extra exhaust emission reduction and still qualify as a clean
fuel fleet vehicle (LEV) and get the temporal TCM exemptions.
Similarly, an ILEV can trade away the vapor benefit and still
qualify as a. CFFV and retain the temporal TCM exemption. An extra
ILEV could trade away its exhaust and vapor emission reductions and
be eligible for no' exemptions/ incentives.
V. Method of Calculation
The method of calculation of credits outlined below is
designed to ensure that emission reduction credits are determined
with confidence. There are three cases: for purchases of 1)
additional clean fuel vehicles, 2) cleaner vehicles, and 3) ILEV
vehicles. In all cases/ the credits accrue to the vehicle owner,
who can then sell them directly to another source or to a broker,
or retain them for internal use.
Credits will be calculated based on the number of miles
traveled by each vehicle each year, adjusted by the degree to which
the vehicle is cleaner than a conventional vehicle as prescribed
below. States may calculate credits in one of two ways: projected
or year-end. A state's choice of method will depend on the needs
of its program. However, under either method, the state must have
a method to verify that credits given reflect actual emissions
savings.
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The projection method of credit calculation ensures that
credits are used during the same year they are generated
According to this method, credits are estimated and allocated at
the beginning of the year they are generated, based on an estimate
of how many miles the vehicle will travel that year. Then, at the
end of the year, the states must follow up with a verification
procedure based on actual vehicle miles traveled, to verify that
estimated emission reductions are the same actual emission
reductions. States using this method must provide a remedy to
correct estimation errors
The year-end method of credit calculation can be used to avoid
the extra paperwork associated with the verification procedure
required by the first method. In the year-end method, states
calculate and allocate credits at the end of the year, based on
actual vehicle miles traveled. Under this method, emission credits
are used during the year after they are generated.
Under either program, credits are to be calculated according
to the following methods, in grams per year of each pollutant. For
the two different methods of calculation, VMT represents either
estimated or actual mileage, depending on which method is used and,
if the first method is used, whether the calculation is the
beginning of the year estimate or the year-end verification.
Method 1. Purchases of Additional Vehicles.
To calculate the credit generated by the purchase of an additional
clean fuel vehicle either under the fleet program or a state
program, the following formula will be applied, for each pollutant:
[additional vehicle benefit x VMT x CF] - credit [grams/year]
where:
(additional vehicle benefit) - In use emission rate change
between conventional standard
and clean fuel standard to
which the vehicle is actually
certified
VMT * vehicle miles traveled, on the clean fuel, in one
year
CF = conversion factor (BSFC x Fuel Econ x Fuel Density) ;
heavy-duty only (see below)
Method 2. Purchases of Cleaner Vehicles.
To calculate the credit generated by the purchase of a cleaner
vehicle under the fleet program, the following formula will be
applied, for each pollutant:
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[cleaner vehicle benefit x VMT x CF] = credit [grams/year]
where
(cleaner vehicle benefit) = In use emission rate reduction
between LBV standard and
standard to which the vehicle
is actually certified
(ULEV, ZEV)
VMT = vehicle miles traveled, on the clean fuel, in one
year
CF = conversion factor (BSFC x Fuel Econ x Fuel Density) /
heavy-duty only (see below)
For heavy-duty vehicles/engines, the above equations require
the use of a conversion factor (CF) to convert the g/BHP-hr in use
emission rate reduction values into gram per mile equivalents.
This factor is a product of the Brake Specific Fuel Consumption
(BSFC), fuel economy, and fuel density. It should be calculated
separately for each vehicle/engine family involved as prescribed in
EPA's heavy-duty engine trading and banking rule (See 55 FR 30584,
July 26, 1990).
Method 3. ILSVs/ Cl«*n Air Vohicl«».
For dedicated fuel vehicles such as ILEVs there will be a
vapor emissions benefit which could be included. This would be
calculated according to the following formula:
[(vapor improvement) x VMT] = credit [grams/year]
where
(vapor improvement)
In use emission rate reduction between
conventional and low vapor emission
vehicles calculated using the latest
version of the Mobile emission factor
model: the difference between the total
vapor emissions for conventional fuel
vehicle (reformulated gasoline) and the
vehicle/fuel being evaluated. This
includes all evaporative categories
(hot soak, diurnal, running loss,
resting loss) as well as refueling for
situations without Stage II controls
and partial benefits for those with
Stage II. (If in lieu of Stage II,
onboard control of refueling emissions
is installed on the vehicle, the vapor
emission reductions will have to be
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adjusted downward approximately ten
percent over those with Stage II.)
VMT = vehicle miles traveled in one year
The current in use emission rate reduction factors needed for
the above calculations are shown in Tables 2, 3, and 4. Tables 2
and 3 provide the appropriate factors for determining the emission
reduction benefits for additional light and heavy duty vehicles.
These tables reflect the difference in in-use emission rates
between a vehicle which meets the Tier 1 standards and one which
meets one of the four possible sets of clean fuel vehicle emission
standards. Credit tables for conversions of previous year vehicles
(1991, 1992, 1993, etc) can be constructed using the emission
factors for the appropriate model year from the Mobile 5 emission
model. Emission reduction benefits for cleaner vehicles are
determined by subtracting the emission reduction benefits of LEVs
from that of ULEVs or ZEVs as appropriate in Tables 2 and 3.
Table 4 contains the vapor emission reduction benefits for
ILEVs with and without refueling controls assuming improved
evaporative controls, onboard diagnostics, and enhanced I/M are in
place and the vehicle is using reformulated gasoline. Slightly
larger emission factors would be expected for dedicated conversions
of vehicles not covered by these requirements. These also would
need to be developed using Mobile 5 evaporative and refueling
emission factors for the model year vehicle and in-use conditions
of interest.
These factors have been developed by EPA's Office of Mobile
Sources for the vehicle classes and standards groups of interest
using the latest emission factor data contained in EPA's Mobile 5
emissions model and other information. These reflect the best
information now available and in many cases are based on in use
data for current technologies and fuels. As better information on
the in-use performance of clean fuel vehicles becomes available
these factors can and should be updated and other categories added
as needed.
When electric vehicles are used, these calculation methods
may be further adjusted to take into account any additional NMHC,
CO, and NOx emissions related to generating the electricity used to
power them. If included, it will be up to the relevant states to
determine the size of that offset, depending on local electricity-
generating factors.
vi. Special Problems
A trading program such as the one described in this document
poses at least two special problems. The first is that credits
could be given for a vehicle that does not actually have reduced
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emissions. The second is the case when vehicles are driven
additional miles to generate extra credits.
The first case, when a vehicle is given credits even though it
does not have reduced emissions, is the more serious problem. This
may occur if the clean fuel vehicle is not properly maintained
and/or it is defective. Since it is proposed that credits be
calculated based on the standards to which vehicles are certified,
and not based on emissions from an emission test on each vehicle,
this problem would be discovered only as a result of emission
inspections of that vehicle type.
While vehicle failures would defeat the purpose of this credit
program, EPA does not believe this will occur at such a rate that
more than the required I/M tests should be mandated. Since all
areas with clean fuel vehicle fleet programs are required to have
I/M programs, EPA believes that it is unlikely that credits would
be allocated for vehicles that fail to reduce emissions. Credits
are calculated annually and most emission failures would be brought
to the attention of EPA and the states during that year through the
I/M programs. In cases where a vehicle type fails an emission
inspection, those vehicles would either not be allocated credits
for that year, or would be allocated a prorated share of credits
based on actual emissions. As noted above, information about the
condition of relevant vehicles in those areas that do not require
annual I/M testing will be derived from the national I/M
experience. Similarly, emission credits would need to be adjusted
if the vehicle model is involved in an emission recall.
EPA believes that the second case, where a vehicle is driven
additional miles only to generate credits, is unlikely to occur.
The additional costs of generating those credits, in both fuel and
time may not be worth the value of the extra credits. However, if
fleets operate their clean fuel vehicles in preference to their
conventional vehicles for the purpose of generating credits, this
is in keeping with the spirit of both programs, which is to
generate fewer emissions. Fleets that adopt this strategy are
entitled to the extra credits they generate. To ensure against
.misrepresentations, states may consider comparing fleet miles
traveled on a year-to-year basis, to detect unlikely increases in
number" of miles traveled. This may lalso be used as a check
against tampered odometers on vehicles as could fuel use records.
VTI. Administration of the Program
As noted above, states would be required to design and
administer their own emission reduction credit programs. However,
EPA advises that all state programs contain elements and methods of
calculation similar to those described above to ensure that
emission reductions are being achieved. If a state does not follow
this guidance, it must show that the emission reductions are
achieved.
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Finally, it should be noted that the states in which the
program will be run have the ultimate responsibility of ensuring
that both the clean fuel vehicle fleet and fleet emission reduction
programs are implemented in accordance with their respective
requirements.
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STATES AND AREAS AFFECTED BY CAA FLEET PROGRAM
ASTSCTIO AREAS: STATES:
1. Atlanta . Georgia
2. Baltimore Maryland
3 . Baton Rouge Louisiana
4 . Beaumont-Port Arthur ... Texas
5. Boston—Lawrence—Worcester (Eastern Massachusetts) Massachusetts
New Hampshire
6. Chicago-Gary-Lake County Illinois,
Indiana
7 . Denver-Boulder . . . Colorado
8. El Paso Texas
9. Greater Connecticut Connecticut
10. Houston-Galveston—Brazoria Texas
11. Los Angeles-South Coast Air Basin California
12. Milwaukee-Racine Wisconsin
13. New York-Northern New Jersey-Long Island Connecticut,
New Jersey,
New York
14. Philadelphia-Wilmington-Trenton Delaware,
Maryland,
New Jersey,
Pennsylvania
15. Providence (All Rhode Island) .. Rhode Island
16. Sacramento Metro California
17. San Diego California
18. San Joaquin Valley California
19. Southeast Desert Modified AQMA California
20. Springfield (Western Massachusetts) Massachusetts
21. Ventura County California
22. Washington (District of Columbia) Maryland,
Virginia,
District of
Columbia
15
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EXHAUST EMISSION REDUCTION RATES
FOR CLEAN FUEL VEHICLES (g/mi)
LDV/LLDT1
TLEV
LBV
ULEV
ZEV
HLDT1
TLEV
LEV
ULEV
ZEV
LLDT2
LEV
ULEV
ZEV
HLDT2
LEV
ULEV
ZEV
NMHC
.062
.093
.120
.342
CO
NOx
.088
147
425
1.527
1.527
6.491
2.354
2.354
7.501
.091
.091
.427
078
115
153
383
- -
1.975
1.975
7.122
- -
.138
.138
.561
073
117
383
1.975
1 . 975
7.122
.008
.138
.561
.012
.229
.739
LLDT1
HLDT1
LLDT2
HLDT2
< 6000 Iba. GVWR (0-3750 Iba. LVIf)
< 6000 Iba. GVWR (3751-5750 Iba. LVW)
GVWR (3751-5750 Iba. TW)
> 6000 Iba
> 6000 Iba. GVWR (>5750 Iba. TW)
16
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Tabl« 3
EXHAUST EMISSION REDUCTION PATES FOR CLEAN FUEL
HEAVY DUTY VEHICLES (g/bhp-hr)
I
LHDGV
LEV
ULEV
ZEV
NMHC + NOx
0.9
1.6
3.5
MHDGV
LEV
ULEV
ZEV
NMHC + NQx
1.4
1.7
3.9
LHDDV
LEV
ULEV
ZEV
0.7
1.5
3.6
MHDDV
LEV
ULEV
ZEV
0.6
1.4
3.4
LHDGV 8,500 - 14,000 Ibs. GVWR
MHDGV 14,001 - 26,000 Ibs. GVWR
LHDDV 8,500 - 19,500 Ibs. GVWR
MHDDV 19,501 - 26,000 Iba. GVWR
VAPOR EMISSION REDUCTION RATES FOR
ILEVfc/CAVs (g/mil«)
LDV
LDT1
LDT2
HDGV
VAPOR
.33
.38
.39
1.23
VAPOR WITH STAGE II CONTROL
.19
.20
.21
-94
17
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ERRATA SHEET
'" - ;- . .'.-' -' :'.. - ; ; •' - .-.- ' •••'•-' '-6/23/93; ' • ..-. -
Conversion Factor Equation: The equation for the calculation of
the conversion factor in the guidance reads:
c.f. = BSFC x Fuel Economy x Fuel Density
equation should read:
c.f. = Fuel Density / (BSFC x Fuel Economy)
18
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