Proposed Mechanism for Obtaining Hybrid Vehicle Credits
The U.S. Environmental Protection Agency (EPA) and the U.S. Department of Transportation National Highway Traffic Safety Administration (DOT/NHTSA) issued proposed greenhouse gas emissions standards and fuel efficiency standards for medium- and heavy-duty engines in a notice of proposed rulemaking (NPRM) on October 26, 2010 (EPA/NHTSA, 2010a,b). On September 15, 2011, the EPA and NHTSA issued final greenhouse gas emissions standards and fuel efficiency standards for medium- and heavy-duty engines and vehicles that are tailored to each of three regulatory categories of heavy-duty vehicles: (1) Heavy-Duty Pickup Trucks and Vans, (2) Vocational Vehicles, and (3) Combination Tractors (EPA/NHTSA, 2011a). The agencies are providing credits for the use of hybrid powertrain technology as an incentive (EPA/NHTSA 2011a,b). The approach to account for the use of a hybrid powertrain when evaluating compliance with the standards is described below.
HEAVY-DUTY PICKUP AND VAN HYBRIDS
Test Procedure
For the heavy-duty pickup truck and van hybrid class of vehicles with gross vehicle weight ratings [GVWRs] between 8,500 and 14,000 lb (that are not already covered under the Model Year 2012-2016 light-duty truck and medium-duty passenger vehicle greenhouse gas [GHG] standards), the agencies have proposed that testing would be done using adjustments to the test procedures developed for light-duty hybrids, using the light-duty Federal Test Procedure (FTP) and the Highway Fuel Economy Test (HWFET), but extending the requirement for chassis certification for CO2 emissions to diesel-powered vehicles. Currently, chassis certification is a gasoline requirement and a diesel option. Manufacturers would be allowed to continue to certify engines for criteria pollutant (non-GHG) requirements as they do today.
Fuel-Consumption Credits
The EPA and NHTSA fuel-consumption standards are expressed on a gal/100 mile basis, and that would apply to a manufacturer’s fleet of heavy-duty pickup trucks and vans with a GVWR from 8,500 to 14,000 lb. The credits for the hybrid vehicle would be calculated according to the Averaging, Banking, and Trading (ABT) program described by an equation for fuel consumption credits given later in this section.
A manufacturer’s credit or debit balance will be determined by calculating its fleet average performance using the data from the FTP and HWFET tests and comparing this data to the manufacturer’s fuel-consumption standards, as determined by its fleet mix, for a given model year. A target standard is determined for each vehicle with a unique payload, towing capacity, and drive configuration (two-wheel versus four-wheel drive). These unique targets, weighted by their associated production volumes, are summed at the end of the model year to derive the production volume-weighted manufacturer annual fleet average standard. A manufacturer would generate credits if its fleet average fuel-consumption level were lower than its standard and would generate debits if its fleet average fuel-consumption level were above that standard.
In addition to production weighting, the credit calculations include a factor for the useful life, in miles, in order to allow the expression of credits in gallons. The following equation is used to calculate credits (debits) and account for the amount that the family limit is below (above) the standard, the payload tons, the sales volume, and the useful life.
Fuel Consumption Credits (gallons) = (FC Std - FC Act) × Volume × UL × 100,
where:
FC Std = Fleet average fuel-consumption standard (gal/100 mile)
FC Act = Fleet average actual fuel-consumption value (gal/100 mile)
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F
Proposed Mechanism for Obtaining Hybrid Vehicle Credits
Fuel-Consumption Credits
The U.S. Environmental Protection Agency (EPA) and the
U.S. Department of Transportation National Highway Traffic
The EPA and NHTSA fuel-consumption standards are
Safety Administration (DOT/NHTSA) issued proposed green-
expressed on a gal/100 mile basis, and that would apply to a
house gas emissions standards and fuel efficiency standards
manufacturer’s fleet of heavy-duty pickup trucks and vans with
for medium- and heavy-duty engines in a notice of proposed
a GVWR from 8,500 to 14,000 lb. The credits for the hybrid
rulemaking (NPRM) on October 26, 2010 (EPA/NHTSA,
vehicle would be calculated according to the Averaging, Bank-
2010a,b). On September 15, 2011, the EPA and NHTSA
ing, and Trading (ABT) program described by an equation for
issued final greenhouse gas emissions standards and fuel
fuel consumption credits given later in this section.
efficiency standards for medium- and heavy-duty engines and
A manufacturer’s credit or debit balance will be determined
vehicles that are tailored to each of three regulatory categories
by calculating its fleet average performance using the data
of heavy-duty vehicles: (1) Heavy-Duty Pickup Trucks and
from the FTP and HWFET tests and comparing this data to
Vans, (2) Vocational Vehicles, and (3) Combination Tractors
the manufacturer’s fuel-consumption standards, as determined
(EPA/NHTSA, 2011a). The agencies are providing credits
by its fleet mix, for a given model year. A target standard is
for the use of hybrid powertrain technology as an incentive
determined for each vehicle with a unique payload, towing
(EPA/NHTSA 2011a,b). The approach to account for the use
capacity, and drive configuration (two-wheel versus four-
of a hybrid powertrain when evaluating compliance with the
wheel drive). These unique targets, weighted by their associ-
standards is described below.
ated production volumes, are summed at the end of the model
year to derive the production volume-weighted manufacturer
annual fleet average standard. A manufacturer would generate
HEAVY-DUTY PICKUP AND VAN HYBRIDS
credits if its fleet average fuel-consumption level were lower
than its standard and would generate debits if its fleet average
Test Procedure
fuel-consumption level were above that standard.
In addition to production weighting, the credit calculations
For the heavy-duty pickup truck and van hybrid class
include a factor for the useful life, in miles, in order to allow
of vehicles with gross vehicle weight ratings [GVWRs]
the expression of credits in gallons. The following equation is
between 8,500 and 14,000 lb (that are not already covered
used to calculate credits (debits) and account for the amount
u nder the Model Year 2012-2016 light-duty truck and
that the family limit is below (above) the standard, the payload
medium-duty passenger vehicle greenhouse gas [GHG]
tons, the sales volume, and the useful life.
standards), the agencies have proposed that testing would be
done using adjustments to the test procedures developed for
Fuel Consumption Credits (gallons) = (FC Std − FC Act)
light-duty hybrids, using the light-duty Federal Test Proce-
× Volume × UL × 100,
dure (FTP) and the Highway Fuel Economy Test (HWFET),
but extending the requirement for chassis certification for
where:
CO2 emissions to diesel-powered vehicles. Currently, chassis
FC Std = Fleet average fuel-consumption standard
certification is a gasoline requirement and a diesel option.
(gal/100 mile)
Manufacturers would be allowed to continue to certify
FC Act = Fleet average actual fuel-consumption value
engines for criteria pollutant (non-GHG) requirements as
(gal/100 mile)
they do today.
166
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167
APPENDIX F
Volume = Total production of vehicles in the regulatory tion reductions that would be realized from their systems in
category the real world. The composite PTO test cycle for utility and
UL = Useful life for the regulatory category (miles) refuse trucks is described in greater detail in EPA/NHTSA
(2011b, see Table 3-23).
VOCATIONAL VEHICLE AND TRACTOR HYBRIDS
Engine Dynamometer Evaluation
Test Procedure
The engine test procedure involves exercising the con-
For vocational vehicles and combination tractors incorpo- ventional engine and the hybrid-engine system based on an
rating hybrid powertrains, the agencies specify two methods engine testing strategy. Real-world functionality would need
for establishing credits. The first method uses chassis dyna- to be accurately represented. The testing would also need to
mometer evaluation of the vehicle, and the second method uses recover vehicle kinetic energy. The agencies specify the use
engine dynamometer evaluation with the powerpack in either a of the Heavy-Duty Engine FTP cycle for evaluation of hybrid
(1) pre-transmission format or a (2) post-transmission format. vehicles, which is the same test cycle specified for engines
Each method requires a comparison test of the actual physi- used in vocational vehicles. Engine dynamometer evaluation
cal product, because the agencies are not aware of analytical may be undertaken in one of two ways:
models that can assess the technology.
1. Pre-transmission power-pack testing, which includes
the engine and hybrid systems in a pre-transmission
Chassis Dynamometer Evaluation format, could utilize existing engine certification duty
cycles. Changes to how the engine certification would
Similar to heavy-duty pickup and van hybrids, to generate
be conducted to address energy capture and idle opera-
credits for hybrid vocational vehicles, full vehicle chassis
tion would need to be evaluated as a complete protocol
dynamometer testing is a straightforward basis for compar-
is developed.
ing fuel consumption performance of hybrid vehicles to
2. Post-transmission power-pack testing, which includes
conventional vehicles. The agencies specify two sets of
the transmission, would require a vehicle-like duty
duty cycles for vocational trucks to evaluate the benefit
cycle, which provides the appropriate speeds and
depending on the vehicle application. The key difference
torques to match field operation.
between the two sets is that one does not include operation
of a power take-off (PTO) unit while the other does. For
example, delivery trucks do not operate a PTO while bucket
Fuel-Consumption Credits
and refuse trucks do.
The duty cycles that apply to hybrid powertrains without Heavy-duty hybrid vehicles and hybrid powertrains can
a PTO system are shown in Table F-1. be certified using an A to B test method. This concept entails
The transient cycle, derived from the California Air testing the conventional vehicle or powertrain, identified as
R esources Board (CARB) Heavy-Duty Truck 5 Mode “A,” and the hybrid version of the vehicle or powertrain,
Cycle, is 668 seconds long and travels 2.84 miles. The cycle identified as “B.” The benefit associated with the hybrid
contains 5 stops and contains 112 seconds of idling. The system for fuel consumption would be determined from the
maximum speed of the cycle is 47.5 mph with an average weighted fuel-consumption results from the tests of each
speed of 15.3 mph. The High Speed and Low Speed Cruise vehicle or hybrid powertrain, as described below:
modes reflect constant speed cycles at 65 mph and 55 mph,
respectively, which are representative of drivers using cruise 1. Improvement Factor = (Fuel Cons_A − Fuel Cons_B)/
control whenever possible. The final rules include a new (Fuel Cons_A)
optional PTO test cycle in addition to the standard set of test 2. Gallons/1,000 ton-mile benefit = Improvement Factor
cycles in order for manufacturers of advanced PTO systems × GEM Fuel Cons Result_B
to demonstrate in the laboratory environment fuel consump-
Note in the above equations that the GEM (Greenhouse Gas
Emissions Model) result would be calculated for the base
vehicle or powertrain without hybridization, and the Improve-
TABLE F-1 Proposed Drive-Cycle Weightings (percent)
ment Factor would account for hybridization of the vehicle or
for Hybrid Vehicles Without Power Take-off
powertrain.
Vehicle Category Transient 55 mph 65 mph The following equation for the credits (debits) accounts
for the amount that the family emission limit is below (above)
Vocational vehicle 75 9 16
Day cab tractor 19 17 64 the standard, the payload tons, the production volume, and
Sleeper cab tractor 5 9 86 the useful life:
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168 REVIEW OF THE 21ST CENTURY TRUCK PARTNERSHIP, SECOND REPORT
Fuel Consumption credit (deficit)(gallons) = (Std-FEL) × Early credits provide an incentive for manufacturers to intro-
(Payload Tons) × (Volume) × (UL) × 103, duce more efficient engines and vehicles earlier than required
by the standards.
where:
Std = Standard associated with the regulatory category
Advanced Technology Credits
( gallons/1,000 ton-mile) (fuel consumption: Gal -
lons/1,000 ton-mile) The final rules include a provision for obtaining credits for
introducing advanced technologies to provide an incentive for
Payload tons = Prescribed payload for each subcategory their introduction. A 1.5 multiplier will be applied to these cred-
(12.5 tons for Class 7 tractors, 19 tons for Class 8 tractors, its, but the total credits are capped in any model year. Hybrid
2.85 tons for light heavy-duty [LHD] vocational, 5.6 tons powertrain designs that include energy storage systems are one
for medium heavy-duty [MHD] vocational, 7.5 tons for of the advanced technologies defined by the agencies.
heavy heavy-duty [HHD] vocational vehicles)
REFERENCES
FEL = Family emission or fuel-consumption limit for the
EPA/NHTSA (Environmental Protection Agency [Office of Transporta-
vehicle family (gallons/1,000 ton miles)
tion and Air Quality]/National Highway Traffic Safety Administration
[Department of Transportation]). 2010a. Greenhouse Gas Emissions
Volume = (Projected or actual) production volume of the Standards and Fuel Efficiency Standards for Medium- and Heavy-
vehicle family Duty Engines and Vehicles. Dockets No. EPA-HQ-OAR-2010-0162 and
No. NHTSA-2010-0079, October 25, 2010. Available at http://www.
regulations.gov.
UL = Useful life of the vehicle (435,000 miles for HHD,
EPA/NHTSA. 2010b. Draft Regulatory Impact Analysis, Proposed Rule-
185,000 miles for MHD, and 110,000 miles for LHD)
making to Establish Greenhouse Gas Emissions Standards and Fuel Ef -
ficiency Standards for Medium- and Heavy-Duty Engines and Vehicles.
EPA-420-D-10-901. October.
Early Credits
EPA/NHTSA. 2011a. Greenhouse Gas Emissions Standards and Fuel Ef-
ficiency Standards for Medium- and Heavy-Duty Engines and Vehicles,
The final rules include an option for a manufacturer to
Final Rules. August 9.
obtain early credits by certifying a subcategory of vehicles
EPA/NHTSA. 2011b. Final Rulemaking to Establish Greenhouse Gas
at fuel-consumption levels below the standard prior to the Emissions Standards and Fuel Efficiency Standards for Medium- and
model year the standard becomes effective. A 1.5 multiplier Heavy-Duty Engines and Vehicles, Regulatory Impact Analysis. EPA-
will be applied to early credits earned in model year 2013. 420-R-11-901. August.