which therefore is projected to be able to comply with the highest
fleet average carbon dioxide emissions compliance levels, should be
treated as establishing the minimum acceptable level of emissions
reductions for the industry. Similarly, no other manufacturers should
exceed the feasible, cost effective level established by that projected
highest footprint manufacturer. The approach, and underlying rationale,
is similar to the approach used by NHTSA before the 2006 truck
standards, whereby the level of a universal standard was established
based on the capabilities of the least capable large manufacturer
(Public Citizen v. NHTSA, 848 F. 2d 256, 259, D.C. Cir. 1988). Although
the backstop would not prohibit the highest footprint manufacturer from
selling higher footprint vehicles, it would prohibit any carbon dioxide
emissions ``backsliding'' that would otherwise be associated with that
increase in footprint. Average carbon dioxide emissions from other
manufacturers could increase, of course, in accordance with the
footprint curve, but in no case could the carbon dioxide emissions
level for any manufacturer increase beyond these backstop levels.
    The passenger car carbon dioxide emissions and mpg backstop levels
shown in Table VI-3 adhere to the methodology described above with one
exception. Based on Chrysler's projected footprint values, its 2011
standard for the 4% per year option would be 325 g/mi, equivalent to a
gasoline vehicle fuel economy of 27.3 mpg. Since the current car CAFE
standard, which acts as an effective fuel economy backstop, is 27.5
mpg, EPA could instead consider a 2011 backstop of 323 g/mi for the 4%
per year option, which is equivalent to a 27.5 mpg gasoline vehicle.
    In this illustrative backstop example, the carbon dioxide emissions
backstop levels would range from 8 to 22 g/mi, or 2 to 8%, higher than
the projected, average industry-wide carbon dioxide levels.

 Table VI-3--Illustrative Backstops for the Fleet Average Carbon Dioxide Emissions Standard (CO2 grams per mile/
                                                      mpg)
----------------------------------------------------------------------------------------------------------------
                                                                             CARS
                                             -------------------------------------------------------------------
                                                  4 percent per year option          Model-optimized option
                                             -------------------------------------------------------------------
                                                 Projected                         Projected
                                               industry-wide       Backstop      industry-wide       Backstop
                                                 CO2 levels                        CO2 levels
----------------------------------------------------------------------------------------------------------------
2010 (base).................................       (323)/27.5  ...............       (323)/27.5  ...............
2011........................................         309/28.7         323/27.5         301/29.5         317/28.0
2012........................................         298/29.8         319/27.8         291/30.5         314/28.3
2013........................................         285/31.1         296/30.0         276/32.1         287/30.9
2014........................................         275/32.3         287/30.9         268/33.2         281/31.6
2015........................................         264/33.6         277/32.0         260/34.1         273/32.5
2016........................................         254/34.9         266/33.4         247/35.9         258/34.4
2017........................................         244/36.3         257/34.5         244/36.4         257/34.5
2018........................................         235/37.7         245/36.2         239/37.2         249/35.7
----------------------------------------------------------------------------------------------------------------

    A second illustrative example of a universal backstop approach
could be modeled on the ``minimum standard'' in the Energy Independence
and Security Act (EISA) of 2007. EISA establishes a fuel economy
backstop for the domestic car class that is equal to 92% of the average
fuel economy level projected for all cars. EPA believes this 92% value
was derived by dividing the current car CAFE standard of 27.5 mpg by
the average industry-wide car fuel economy performance over the past
several years. The car CAFE standard, in effect, has served as a
backstop for those manufacturers that have chosen not to pay CAFE
penalties. Applying this model to a carbon dioxide emissions backstop
would involve dividing the average projected industry-wide carbon
dioxide emissions levels by 0.92, or multiplying by a factor of 1.087,
an increase of 8.7%, to generate a universal backstop level that would
apply to all manufacturers. Under this approach, the backstop levels
for the 4% per year and model-optimized standards in Table VI-3 would
be greater than the backstop levels discussed earlier in every case,
ranging from 3 to 23 g/mi higher. This alternative approach yields
backstop levels 20 to 31 g/mi higher than the projected, average
industry-wide standards.
    For the backstop approaches discussed above, all automakers would
have the same uniform backstop for domestic and import cars, and a
higher uniform backstop for trucks. These universal approaches would
make the backstop more of a constraint on those manufacturers that sold
vehicles with higher average footprint levels and less of a constraint
on those automakers that sold vehicles with lower average footprint
levels.
    An alternative backstop approach could be to establish unique
maximum numerical carbon dioxide emissions values that would apply to
different automakers (e.g., X g/mi for Automaker A, and Y g/mi for
Automaker B) and that would become the effective fleet average standard
for an individual automaker when that automaker would otherwise be
allowed to meet a higher fleetwide average carbon dioxide emissions
value based exclusively on the footprint curve. The rationale for this
type of approach would be that since manufacturers start at different
average footprint levels, manufacturer-specific backstop values could
provide greater insurance against carbon dioxide emissions backsliding
for all manufacturers, rather than just those manufacturers that sold
vehicles with higher average footprint levels. One illustrative example
of this type of approach would be to base the annual backstop for each
manufacturer on its 2010 carbon dioxide emissions baseline, reducing it
by the same percentage each year. A similar approach would base the
annual backstop for the highest-footprint manufacturer on its 2010
carbon dioxide emissions baseline reduced by a percentage each year,
the annual backstop for the lowest-footprint automaker on its 2010
carbon dioxide emissions baseline reduced by a lesser percentage per
year, and the annual backstop values for other manufacturers on annual
percentage reductions between the higher and lower percentages. This
latter approach would yield backstop values that would be somewhat more
binding on manufacturers that sold vehicles with higher average
footprint values, yet still binding to some degree on all automakers.
This approach would also limit the degree to which manufacturers that
sold vehicles with lower average footprint values could increase
average footprint values over time.
    A combination of the universal and manufacturer-specific approaches
could be to begin with manufacturer-specific backstop values, and to
transition to uniform backstop values over a 5 or 10 year period.
    Another alternative backstop approach would not set a maximum
numerical carbon dioxide emissions value for individual manufacturers,
but would establish mathematical functions that would automatically
increase the stringency of and/or ``flatten'' the footprint curves for
future years when actual industry-wide carbon dioxide emissions
performance in the future is found to fall short of EPA's projections
at the time of promulgation. For example, at the time of promulgation,
EPA could assume a certain average industry-wide carbon dioxide g/mi
emissions level for 2011-2012. If, in 2013, EPA found that the average
industry-wide emissions level in 2011-2012 was higher than projected in
the final rule (and therefore the carbon dioxide emissions reductions
were lower than projected because of higher than projected average
footprint levels), then the backstop provisions would be triggered and
the footprint curves for future years (say, 2016 and later) would be
automatically changed to be more stringent and/or flatter in shape.
This approach would reframe the backstop issue in terms of industry-
wide emissions performance, rather than in terms of individual
automaker emissions performance.
    In lieu of a backstop, another approach would be to flatten (i.e.,
reduce the slope of) the carbon dioxide emissions-footprint curve such
that there would a major disincentive for automakers to increase
vehicle footprint. EPA invites comments on the pros and cons of this
approach relative to a backstop.

[[Continued on page 44453]]

]

[[pp. 44453-44502]] Regulating Greenhouse Gas Emissions Under the Clean Air Act

[[Continued from page 44452]]

    In conclusion, EPA seeks comment on whether a CO2
emissions backstop is an appropriate complement to a footprint-based
regulatory approach under the CAA to ensure that the program would
achieve a minimum level of feasible carbon dioxide emissions
reductions. EPA invites comments on both the potential backstop
approaches discussed above, as well as suggestions for other
approaches.
iii. Potential Test Procedures for Light-Duty Vehicle Tailpipe
CO2 Emissions
    For the program options EPA analyzed to date, EPA would expect
manufacturers and EPA to measure CO2 for certification and
compliance purposes over the same test procedures currently used for
measuring fuel economy, except for A/C-related CO2
emissions. This corresponds with the data used in our analysis of the
potential footprint-based CO2 standards presented in section
VI.B.1.b of this advance notice, as the data on control technology
efficiency was also developed in reference to these test procedures.
These procedures are the Federal Test Procedure (FTP or ''city'' test)
and the Highway Fuel Economy Test (HFET or ''highway'' test). EPA
established the FTP for emissions measurement in the early 1970s. In
1976, in response to requirements in the Energy Policy and Conservation
Act (EPCA), EPA extended the use of the FTP to fuel economy measurement
and added the HFET. The provisions in the 1976 regulation, effective
with the 1977 model year, established procedures to calculate fuel
economy values both for labeling and for CAFE purposes. Under EPCA, EPA
is required to use these procedures (or procedures which yield
comparable results) for measuring fuel economy for cars for CAFE
purposes, but not for fuel economy labeling purposes. EPCA does not
impose this requirement on CAFE test procedures for light trucks, but
EPA does use the FTP and HFET for this purpose.
    On December 27, 2006, EPA established new ``5-cycle'' test
procedures for fuel economy labeling--the information provided to the
car-buying public to assist in making fuel economy comparisons from
vehicle to vehicle. These procedures were originally developed for
purposes of criteria emissions testing, not fuel economy labeling,
pursuant to section 206(h) of the Clean Air Act, which requires EPA to
review and revise as necessary test procedures for motor vehicles and
motor vehicle engines ``to insure that vehicles are tested under
circumstances which reflect the actual current driving conditions under
which motor vehicles are used.'' In updating the fuel economy labeling
regulations, EPA determined that these emissions test procedures take
into account several important factors that affect fuel economy in the
real world but are missing from the FTP and HFET tests. Key among these
factors are high speeds, aggressive accelerations and decelerations,
the use of air conditioning, and operation in cold temperatures.
Consistent with section 206 (h), EPA revised its procedures for
calculating the label estimates so that the miles per gallon (mpg)
estimates for passenger cars and light-duty trucks would better reflect
what consumers achieve in the real world. Under the new methods, the
city miles per gallon estimates for the manufacturers of most vehicles
have dropped by about 12% on average relative to the previous
estimates, with estimates for some vehicles dropping by as much as 30%.
The highway mpg estimates for most vehicles dropped on average by about
8%, with some estimates dropping by as much as 25% relative to the
previous estimates. The new test procedures only affect EPA's vehicle
fuel economy labeling program and do not affect fuel economy
measurements for the CAFE standards, which continue to be based on the
original 2-cycle test procedures (FTP/HFET).
    EPA continues to believe that the new 5-cycle test procedures more
accurately predict in-use fuel economy than the 2-cycle test
procedures. Although, as explained below, to date there has been
insufficient information to develop standards based on 5-cycle test
procedures, such information could be developed and there is no legal
constraint in the CAA to developing such standards. Indeed, section
206(h) provides support for such an approach. Now that automotive
manufacturers are using the 5-cycle test procedure for labeling
purposes, we anticipate significant amount of data regarding the impact
of the 5-cycle test on vehicle CO2 emissions will be made
available to the Agency over the next several years.
    However, for the programs analyzed in the Light-duty Vehicle TSD,
EPA used the original 2-cycle test. Indeed, data were simply lacking
for the efficiencies of most fuel economy control measures as measured
by 5-cycle tests. Thus, existing feasibility studies and analyses, such
as the 2002 National Academy of Sciences (NAS) and the 2004 Northeast
States Center for a Clean Air Future (NESCCAF) studies that examined
technologies to reduce CO2, were based on the 2-cycle test
procedures. However, as noted above, we expect that new data regarding
the 5-cycle test procedures will be made available and could be
considered in future analysis.
    It is important to note, however, that all of our benefits inputs,
modeling and environmental analyses underlying the potential programs
analyzed in the Light-duty Vehicle TSD accounted for the difference
between emissions levels as measured by the 2-cycle test and the levels
more likely to actually be achieved in real world performance. Thus,
EPA applied a 20% conversion factor (2-cycle emissions result divided
by 0.8) to convert industry-wide 2-cycle CO2 emissions test
values to real world CO2 emissions factors. EPA used this
industry-wide conversion factor for all of its emission reduction
estimates, and calculated such important values as overall emission
reductions, overall benefits, and overall cost-effectiveness using
these corrected values. In reality, this conversion factor is not
uniform across all vehicles. For example, the conversion factor is
greater than 20% for vehicles with higher fuel economy/lower
CO2 values and is less than 20% for vehicles with lower fuel
economy/higher CO2 values. But to simplify the technology
feasibility analysis, the analysis assumed a uniform conversion factor
of 20% for all vehicles. EPA does not believe the overall difference
would have a significant effect on the standards because the errors on
either side of 20% tend to offset one another.
    EPA thus analyzed CO2 standards based on the 2-cycle
test procedures for our analysis to date. EPA would expect to continue
to gain additional experience and data on the 5-cycle test procedures
used in the labeling program. If EPA determined that analyzing
potential CO2 standards based on these test procedures would
result in more robust control of those emissions, we would consider
this in future analyses. EPA requests comments on the above test
procedure issues, and the relative importance of using the 2-cycle
versus the 5-cycle test in any future EPA action to establish standards
for light-duty vehicle tailpipe CO2 emissions.
2. Heavy-Duty Trucks
    Like light-duty vehicles, EPA's regulatory authority to address
pollution from heavy-duty trucks comes from section 202 of the CAA. The
Agency first exercised this responsibility for heavy-duty trucks in
1974. Since that time, heavy-duty truck and diesel engine technologies
have continued to improve, and the Agency has set increasingly
stringent emissions standards (today's diesel engines are 98% cleaner
than those from 1974). Over that same period, freight shipment

by heavy-duty trucks has more than doubled. Goods shipped solely by
truck account for 74% of the value of all commodities shipped within
the United States. Trucked freight is projected to double again over
the next two decades, growing from 11.5 billion tons in 2002 to over
22.8 billion tons in 2035.\139\ Total truck GHG emissions are expected
to grow with this increase in freight.
---------------------------------------------------------------------------

    \139\ Government Accountability Office. Freight Transportation:
National Policy and Strategies Can Help Improve Freight Mobility
GAO-08-287. Report to the Ranking Member, Committee on Environment
and Public Works, U.S. Senate. January 2008.
---------------------------------------------------------------------------

    Reflecting important distinctions between light and heavy-duty
vehicles, section 202 gives EPA additional guidelines for heavy-duty
vehicle regulations for certain pollutants, including defined
regulatory lead time criteria and authority to address heavy-duty
engine rebuild practices. The Agency has further used the discretion
provided in the CAA to develop regulatory programs for heavy-duty
vehicles that reflect their primary function. Key differences between
our light-duty and heavy-duty programs include vehicle standards for
cars versus engine standards for heavy-duty trucks, gram per distance
(mile) standards for cars versus gram per work (brake horsepower-hour)
for trucks, and vehicle test procedures for cars versus engine-based
tests for trucks. EPA has thus determined that in the heavy-duty
sector, the appropriate metric to evaluate performance is per unit of
work and that engine design plays a critical role in controlling
criteria pollutant emissions. EPA's rules also reflect the nature of
the heavy-duty industry with separate engine and truck manufacturers.
As EPA considers the best way to address GHG emissions from the heavy-
duty sector, we will again be considering the important ways that
heavy-duty vehicles differ from light-duty vehicles.
    In this section, we will characterize the heavy-duty GHG emissions
inventory, broadly discuss the technologies available in the near- and
long-term to reduce heavy-duty truck GHG emissions, and discuss
potential regulatory options to address these emissions. We invite
comment on the issues that are relevant to considering potential GHG
emission standards for heavy-duty trucks. In particular, we invite
commenters to compare and contrast potential heavy-duty solutions to
our earlier discussion of light-duty vehicles and our existing heavy-
duty criteria pollutant control program in light of the differences
between GHG emissions and traditional criteria air pollutants.
a. Heavy-Duty Truck GHG Emissions
    Heavy-duty on-road vehicles emitted 401 million metric tons of
CO2 emissions in 2006, or approximately 19% of the mobile
source CO2 emissions, the largest mobile source sub-category
after light-duty vehicles.\140\ CO2 emissions from these
vehicles are expected to increase significantly in the future, by
approximately 29% between 2006 and 2030.\141\
---------------------------------------------------------------------------

    \140\ Emissions data in this section are from the United States
Environmental Protection Agency. Inventory of U.S. Greenhouse Gas
Emissions and Sinks: 1990-2006. EPA 430-R-08-005. April 2008.
    \141\ Growth data in this section is from United States
Department of Energy, Energy Information Administration. Annual
Energy Outlook 2008. DOE/EIA-0383. April 2008.
---------------------------------------------------------------------------

    Diesel powered trucks comprise 91% of the heavy-duty CO2
emissions, with the remaining 9% coming from gasoline and natural gas
engines. Heavy-duty GHG emissions come primarily from two types of
applications, combination and single unit trucks. Combination trucks
constitute 75% of the total heavy-duty GHG emissions--44% from long-
haul and 31% from short-haul operations. Short-haul single unit trucks
are the third largest source at 19%. The remaining 5% consists of long-
haul single unit trucks; intercity, school, and transit buses; refuse
trucks, and motor home emissions.\142\
---------------------------------------------------------------------------

    \142\ Breakdown of emissions data in this section is from United
States Environmental Protection Agency. MOVES model. April 8, 2008.
---------------------------------------------------------------------------

    GHG emissions from heavy-duty trucks are dominated by
CO2 emissions, which comprise approximately 99% of the
total, while hydrofluorocarbon and N2O emissions represent
0.5% and 0.3%, respectively, of the total emissions on a CO2
equivalent basis.
b. Potential for GHG Emissions Reductions From Heavy-Duty Trucks
    Based on the work from EPA's SmartWay Transport Partnership and the
21st Century Truck Partnership, we see a potential for up to a 40%
reduction in GHG emissions from a typical heavy-duty truck in the 2015
timeframe, with greater reductions possible looking beyond 2015,
through improvements in truck and engine technologies.\143\ While
highly effective criteria pollutant control has been realized based on
engine system regulation alone, the following sections make clear that
GHG emissions improvements to truck technology provide a greater
potential for overall GHG emission reductions from this sector.
---------------------------------------------------------------------------

    \143\ 21st Century Truck Partnership. Technology Roadmap for the
21st Century Truck Program. 21CT-001. December 2000. http://
www.doe.gov/bridge.
---------------------------------------------------------------------------

    In this section, we will provide a brief summary of the potential
for GHG emission reductions in terms of engine technology, truck
technology and changes to fleet operations. The public docket for this
Advance Notice includes a technical memorandum from EPA staff
summarizing this potential in greater detail.\144\ In discussing the
potential for CO2 emission reductions, it can be helpful to
think of work flow through a truck's system. The initial work input is
fuel. Each gallon of diesel fuel has the potential to produce some
amount of work and will produce a set amount of CO2 (about
22 lbs. of CO2 per gallon of diesel fuel). The engine
converts the chemical energy in the fuel to useable work to move the
truck. Any reductions in work demanded of the engine by the vehicle or
improvements in engine fuel conversion efficiency will lead directly to
CO2 emission reductions. Current diesel engines are about
35% efficient over a range of operating conditions with peak efficiency
levels of a little over 40%. This means that approximately one-third of
the fuel's chemical energy is converted to useful work and two-thirds
is lost to waste heat in the coolant and exhaust. In turn, the truck
uses this work output from the engine to overcome vehicle aerodynamic
drag (53%), tire rolling resistance (32%), and friction in the vehicle
driveline (6%) and to provide auxiliary power for components such as
air conditioning and lights (9%).\145\ While it may be intuitive to
look first to the engine for CO2 reductions given that only
about one-third of the fuel is converted to useable work, it is
important to realize that any improvement in vehicle efficiency reduces
both the work demanded and also the energy wasted in proportional
amounts.
---------------------------------------------------------------------------

    \144\ Summary of GHG Emission Control Technologies for Heavy-
Duty Trucks, Memorandum to Docket XXX, May 2008.
    \145\ Approximate truck losses at 65 mph from 21st Century Truck
Partnership. 21st Century Truck Partnership Roadmap/Technical White
Papers: Engine Systems. 21CT-003. December 2006. http://www.doe.gov/
bridge.
---------------------------------------------------------------------------

    In evaluating the potential to reduce GHG emissions from trucks and
operations as a whole, it will be important to develop an appropriate
metric to quantify GHG emission reductions. As discussed above, our
current heavy-duty regulatory programs measure emissions expressed on a
mass per work basis (g/bhp-hr). This approach has proven highly
effective at controlling criteria pollutant emissions while normalizing
the diverse range of

heavy-duty vehicle applications to a single engine-based test metric.
While such an approach could be applied to evaluate CO2
emission reductions from heavy-duty engines, it would not readily
provide a mechanism to measure and compare reductions due to vehicle
improvements. Hence, we will need to consider other performance metrics
such as GHG emissions per ton-mile. We request comment on what types of
metrics EPA should consider to measure and express GHG emission rates
from heavy-duty trucks.
    We discuss below the wide range of engine, vehicle, and operational
technologies available to reduce GHG emissions from heavy-duty trucks.
Our discussion broadly assesses the availability of these technologies
and their GHG emissions reduction potential. We request comment on all
aspects of our current assessment summarized here and in more detail in
our technical memorandum, including supporting data with regard to
technology costs, GHG reduction effectiveness, the appropriate GHG
metric to evaluate the technology and the timeframe in which these
technologies could be brought into the truck market. More generally, we
request comment on the overall GHG emissions reductions that can be
achieved by heavy-duty trucks in the 2015 and 2030 timeframes.
i. Engine
    The majority of heavy-duty vehicles today utilize turbocharged
diesel engines. Diesel engines are more efficient compared to gasoline
engines due to the use of higher compression ratios, the ability to run
with lean air-fuel mixtures, and the ability to run without a throttle
for load control. Modern diesel engines have a peak thermal efficiency
of approximately 42%, compared to gasoline engines that have a peak
thermal efficiency of 30%. Turbochargers increase the engine's power-
to-weight ratio and recover some of the exhaust heat energy to improve
the net efficiency of the engine.
    Additional engine improvements could increase efficiency through
combustion improvements and reductions of parasitic and pumping losses.
Increased cylinder pressure, waste heat recovery, and low viscosity
lubricants could reduce CO2 emissions, but are not widely
utilized in the heavy-duty industry. Individual improvements have a
small impact on engine efficiency, but a combination of approaches
could increase efficiency by 20% to achieve a peak engine efficiency of
approximately 50%.\146\
---------------------------------------------------------------------------

    \146\ 21st Century Truck Partnership. 21st Century Truck
Partnership Roadmap/Technical White Papers: Engine Systems. 21CT-
003. December 2006. http://www.doe.gov/bridge.
---------------------------------------------------------------------------

    Waste heat recovery technologies, such as Rankine bottoming cycle,
turbocompounding and thermoelectric materials, can recover and convert
engine waste heat to useful energy, leading to improvements in the
overall engine thermal efficiency and consequent reduction in
CO2 emissions. We request comment on the potential of these
technologies to lower both GHG emissions and overall heavy-duty vehicle
operating costs.
    In section VI.D below, we discuss the Renewable Fuel Standard (RFS)
program and more broadly the overall role of fuel changes to reduce GHG
emissions. As we have previously noted, the Agency has addressed
vehicle emissions through a systems-based approach that integrates
consideration of fuel quality and vehicle or engine emission control
systems. For example, removing lead from gasoline and sulfur from
diesel fuel has enabled the introduction of very clean gasoline and
diesel engine emission control technologies. A systems approach may be
a means to address GHG emissions as well. Since 1989, European engine
maker Scania has offered an ethanol powered heavy-duty diesel cycle
engine with traditional diesel engine fuel efficiency (the current
version offers peak thermal efficiency of 43%).\147\ Depending on the
ethanol production pathway, such an approach could offer a significant
reduction in GHG emissions from a life cycle perspective when compared
to more traditional diesel fuels. We request comment on the potential
for a systems approach considering alternate fuel and engine
technologies to reduce GHG emission from heavy-duty trucks. We also
request comment on how EPA might structure a program to appropriately
reflect the potential for such GHG emission reductions.
ii. Vehicle systems
    An energy audit of heavy-duty trucks shows that vehicle efficiency
is strongly influenced by systems outside of the engine. As noted
above, aerodynamics, tire rolling resistance, drivetrain, and weight
are areas where technology improvements can significantly reduce GHG
emissions through reduced energy losses. The fuel savings benefits of
many of these technologies often offset the additional costs.
Opportunities for HFC and additional CO2 reductions are
available through improved air conditioning systems.
---------------------------------------------------------------------------

    \147\ Green Car Congress. Scania Extending Heavy-Duty Ethanol
Engine Technology to Trucks. April 15, 2008. http://
www.greencarcongress.com/2008/04/scania-extendin.html (April 30,
2008).
---------------------------------------------------------------------------

    For a typical combination tractor-trailer truck traveling at 65
mph, energy losses due to aerodynamic drag can total over 21% of the
total energy consumed.\148\ A recent study between industry and the
federal government demonstrated that reducing the tractor-trailer gap
and adding trailer side skirts, trailer boat tails, and aerodynamic
mirrors can reduce aerodynamic drag by as much as 23%. If aerodynamic
drag were reduced from 21% to 15% (a 23% reduction), GHG emissions at
65 mph would be reduced by almost 12%.\149\ The cost of aerodynamic
equipment installed on a new or existing trailer is generally paid back
within two years.\150\ As aerodynamic designs become more
sophisticated, more consistency in how aerodynamics is measured is
needed. There is no single, consistent approach used by industry to
measure the coefficient of aerodynamic drag of heavy trucks. As a
result, it is difficult for fleets to understand which truck
configurations have the lowest aerodynamic drag. We request comment on
the best approach to evaluate aerodynamic drag and the impact of
aerodynamic drag on truck GHG emissions.
---------------------------------------------------------------------------

    \148\ 21st Century Truck Partnership. Technology Roadmap for the
21st Century Truck Program. 21CT-001. December 2000. http://
www.doe.gov/bridge.
    \149\ United States Department of Energy, Lawrence Livermore
National Laboratory. Working Group Meeting on Heavy Vehicle
Aerodynamic Drag: Presentation, Summary of Contents and Conclusion.
UCRL-TR-214683. May 2005.
    \150\ Bachman, L. Joseph,; Anthony Erb; Cheryl Bynum. Effect of
Single Wide Tires and Trailer Aerodynamics on Fuel Economy and
NOx Emissions of Class 8 Line-Haul Tractor-Trailers. SAE
Paper 2005-01-3551. 2005.
---------------------------------------------------------------------------

    For a typical combination tractor-trailer truck traveling at 65
mph, energy losses due to tire rolling resistance can total nearly 13%
of the total energy consumed.\151\ Approximately 80-95% of the energy
losses from rolling resistance occur as the tire flexes and deforms
when it meets the road surface, due to viscoelastic heat dissipation in
the rubber. For heavy trucks, a 10% reduction in rolling resistance can
reduce GHG emissions by 1-3%.\152\ Improvements of this magnitude and
greater have already been demonstrated, and continued innovation in
tire design

has the potential to achieve even larger improvements in the future.
Specifying single wide tires on a new combination truck can have a
lower initial cost and lead to immediate fuel savings.\153\ Despite the
well-understood benefits of lower rolling resistance tires,
manufacturers differ in how they assess tire rolling resistance. We
seek comment on the potential for low rolling resistance tires to lower
GHG emissions, the need for consistent protocols to measure tire
rolling resistance, and the need for a common ranking or rating system
to provide tire rolling resistance information to the trucking
industry.
---------------------------------------------------------------------------

    \151\ 21st Century Truck Partnership. Technology Roadmap for the
21st Century Truck Program. 21CT-001. December 2000. http://
www.doe.gov/bridge.
    \152\ 21st Century Truck Partnership. Technology Roadmap for the
21st Century Truck Program. 21CT-001. December 2000. http://
www.doe.gov/bridge.
    \153\ United States Environmental Protection Agency. A Glance at
Clean Freight Strategies: Single Wide-Based Tires. EPA420-F-04-004.
February 2004.
---------------------------------------------------------------------------

    Hybrid technologies, both electric and hydraulic, offer significant
GHG reduction potential. The hybrid powertrain is a combination of two
or more power sources: an internal combustion engine and a second power
source with an energy storage and recovery device. Trucks operating
under stop-and-go conditions, such as urban delivery trucks and refuse
trucks, lose a significant amount of energy during braking. In
addition, engines in most applications are designed to perform under a
wide range of requirements and are often oversized for the majority of
their requirements. Hybrid powertrain technologies offer opportunities
to capture braking losses and downsize the engine for more efficient
operation. We invite comment on the potential of GHG reductions from
hybrids in all types of heavy-duty applications.
    Currently most truck auxiliaries, such as the water pump, power
steering pump, air conditioning compressor, air compressor and cooling
fans, are mechanical systems typically driven by belts or gears off of
the engine driveshaft. The auxiliary systems are inefficient because
they produce power proportionate to the engine speed regardless of the
actual vehicle requirements and require conversion of fuel energy to
electrical or mechanical work. If systems were driven by electrical
systems they could be optimized for actual requirements and reduced
energy consumption. We request comment on the potential for these
auxiliary systems to lower GHG emissions from heavy-duty trucks.
    Air conditioning systems are responsible for GHG emissions from
refrigerant leakage and from the exhaust emissions generated by the
engine to produce the load required to run the air conditioning. The
emissions due to leakage can be reduced by the use of improved sealing
designs, low-permeation hoses, and refrigerant substitution. Replacing
today's refrigerant, HFC-134a, which has a high global warming
potential (GWP=1,300), with HFC-152a (GWP=120) or CO2
(GWP=1) reduces the impact of the air conditioning leakage on the
environment.\154\ The load requirements of the air conditioning system
can be reduced through the use of improved condensers, evaporators, and
variable displacement compressors. We request comment on the impact of
air conditioning improvements on GHG reductions in heavy-duty trucks.
iii. Operational
---------------------------------------------------------------------------

    \154\ Frey, H. Christopher and Po-Yao Kuo. Best Practices
Guidebook for GHG Emissions Reductions in Freight Transportation.
Prepared for U.S. Department of Transportation via Center for
Transportation and the Environment. October 2007. Pages 26-27.
---------------------------------------------------------------------------

    The operation of the truck, including idle time and vehicle speed,
also has significant impact on the GHG emissions. Technologies that
improve truck operation exist and provide benefits to owners through
reduced fuel costs.
    Idling trucks emit a significant amount of CO2 emissions
(as well as criteria pollutants). On average, a typical truck will emit
18 pounds of CO2 per hour of idling.\155\ Long haul truck
idle reduction technologies can reduce main engine idling while still
meeting cab comfort needs. Some idle reduction technologies have no
upfront cost for the truck owner and hence represent an immediate
savings in operating costs with lower GHG emissions. Other idle
reduction technologies pay back within three years.\156\ In addition to
providing information about these systems, EPA seeks comment on whether
it should work with stakeholders to develop a formal evaluation
protocol for the effectiveness, cost, durability, and operability of
various idle-reduction technologies.
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    \155\ United States Environmental Protection Agency. A Glance at
Clean Freight Strategies: Idle Reduction. EPA420-F-04-009. February
2004.
    \156\ EPA SmartWay Transport Partnership, Technology Package
Savings Calculator, http://www.epa.gov/smartway/calculator/
loancalc.htm.
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    Vehicle speed is the single largest operational factor affecting
CO2 emissions from large trucks. A general rule of thumb is
that every mph increase above 55 mph increases CO2 emissions
by more than 1%. Speed limiters are generally available on new trucks
or as a low-cost retrofit, and assuming a five mph decrease in speed,
payback occurs within a few months.\157\
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    \157\ American Trucking Associations Petition to National
Highway Traffic Safety Administration, (Docket NHTSA-2007-26851,
Document ID NHTSA-2007-26851-0005), October 20, 2006, and American
Trucking Associations Comment to Docket (Docket NHTSA-2007-26851,
Document ID NHTSA-2007-26851-3708), March 27, 2007.
---------------------------------------------------------------------------

    Automatic tire inflation systems maintain proper inflation
pressure, and thereby reduce tire rolling resistance. Studies indicate
that automatic tire inflation systems result in about 0.5 to 1%
reduction of CO2 emissions for a typical truckload or less-
than-truckload over-the-road trucking fleet.\158\ Automatic tire
inflation systems can pay back in less than four years, assuming
typical underinflation rates.
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    \158\ mission reduction and payback information from United
States Environmental Protection Agency. A Glance at Clean Freight
Strategies: Automatic Tire Inflation Systems. EPA420-F-04-010.
February 2004.
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    All of the technologies summarized here can provide real GHG
reductions while providing value to the truck owner through reduced
fuel consumption. We request comment on the potential of these specific
technologies and on any other technologies that may allow vehicle
operators to reduce overall GHG emissions.
c. Regulatory Options for Reducing GHGs From Heavy-Duty Trucks
    In developing any GHG program for heavy-duty vehicles, we would
rely on our past experience addressing the multifaceted characteristics
of this sector. In the following sections, we discuss three potential
regulatory approaches for reducing GHG emissions from the heavy-duty
sector. We request comments on all aspects of these options. We also
encourage commenters to suggest other approaches that EPA should
consider to address GHG emissions from heavy-duty trucks, recognizing
that there are some important differences between criteria air
pollutants and GHG emissions.
    The heavy-duty engine manufacturers have made great strides in
reducing criteria pollutant emissions. We know these same manufacturers
have already achieved GHG emission reductions through the introduction
of more efficient engine technologies, and have the potential to
realize even greater reductions. We estimate that approximately 30% of
the overall GHG emission reduction potential from this sector comes
from engine improvements, 60% from truck improvements, and 10% from
operational improvements based on the technologies outlined in the 21st
Century Truck roadmap and Best Practices Guidebook for GHG Emissions
Reductions in Freight Transportation. We request comment on our
assessment

of the relative contributions of engine, truck, and operational
technologies.
    The first approach we could consider would be a regulatory program
based on an engine CO2 standard or weighted GHG standard
including N2O and methane. One advantage to this option is
its simplicity because it preserves the current regulatory and market
structures. The heavy-duty engine manufacturers are familiar with
today's certification testing and procedures. They have facilities,
engine dynamometers, and test equipment to appropriately measure
emissions. The same equipment and test procedures can be, and already
are, used to measure CO2 emissions. Measuring and reporting
N2O and methane emissions would require relatively simple
additions to existing test cell instrumentation. We request comment
regarding issues that EPA should consider in evaluating this option and
the most appropriate means to address the issues raised. We recognize
that an engine-based regulatory structure would limit the potential GHG
emission reductions compared to programs that include vehicle
technologies and the crediting of fleets for operational improvements.
The other approaches considered below would have the potential to
provide greater GHG reductions by providing mechanisms to account for
vehicle and fleet operational changes.
    Recognizing that GHG emissions could be further reduced through
improvements to both engines and trucks, we request comment on an
alternative test procedure that would include vehicle aspects in an
engine-based standard. This option would still be based on an engine
standard. However, it would provide a mechanism to adjust the engine
test results to account for improvements in vehicle design. For
example, if through an alternate test procedure (e.g., a vehicle
chassis test) a hybrid truck were shown to reduce GHG emissions by 20%,
under this option an engine based GHG test result could be adjusted
downward by that same 20%. In this way, we could reflect a range of
vehicle or perhaps even operational changes into an engine based
regulatory program. In fact, we are already developing such an approach
for a vehicle based change to provide a better mechanism to evaluate
criteria emissions from hybrid vehicles.\159\ We are currently working
with the heavy-duty industry to develop these new alternate test
procedures and protocols. These new procedures could provide a
foundation for regulatory programs to address GHG emissions as well. We
request comment on the potential for alternate test procedures to
reflect vehicle technologies in an engine based GHG regulatory program.
---------------------------------------------------------------------------

    \159\ As discussed in section VI.C.2, we have also applied a
similar alternate test procedure approach in our new locomotive
standards (see 40 CFR 1033.530(h)).
---------------------------------------------------------------------------

    A second potential regulatory option for heavy-duty truck GHG
emissions would be to follow a model very similar to our current light-
duty vehicle test procedures. Each truck model could be required to
meet a GHG emissions standard based on a specified drive cycle. The
metric for the standard could be either a weighted GHG gram/mile with
prescribed test weight and payload or GHG gram/payload ton-mile to
recognize that heavy-duty trucks perform work. This option would
reflect an important change from our current regulatory approach for
most heavy-duty vehicles by direct regulation of trucks (and therefore
truck manufacturers) rather than engines.\160\ As discussed earlier in
this section, we have historically regulated heavy-duty engines rather
than vehicles reflecting in part the heavy-duty industry structure and
in part the preeminence of engine technology in controlling
NOX and PM emissions. Clearly truck design plays a much more
important role in controlling GHG emissions due to significant energy
losses through aerodynamic drag and tire rolling resistance, and
therefore, this option directly considers the regulation of heavy-duty
trucks. We request comment on all aspects of this option including the
appropriate test metric, the need to develop new test procedures and
potential approaches for grouping heavy-duty vehicles into
subcategories for GHG regulatory purposes.
---------------------------------------------------------------------------

    \160\ For some years EPA has allowed gasoline and other non-
diesel vehicle manufactures to certify to and comply with a vehicle
based standard as compared to en engine based standard, at their
option. See, e.g., 40 CFR 86.005-10.
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    As described earlier, there are a number of technologies and
operational changes that heavy-duty fleet operators can implement to
reduce both their overall operating costs and their GHG emissions.
Therefore, a third regulatory option that could be considered as a
complement to those discussed previously would be to allow heavy-duty
truck fleets to generate GHG emissions credits for applying
technologies to reduce GHG emissions, such as idle reduction, vehicle
speed limiters, air conditioning improvements, and improved aerodynamic
and tire rolling resistance. In order to credit the use of such
technologies, EPA would first need to develop procedures to evaluate
the potential for individual technologies to reduce GHGs. Such a
procedure could be based on absolute metrics (g/mile or g/ton-mile) or
relative metrics (percent reductions). We would further need to address
a wide range of complex potential issues including mechanisms to ensure
that the reductions are indeed realized in use and that appropriate
assurance of such future actions could be provided at the time of
certification, which occurs prior to the sale of the new truck. Such a
regulatory program could offer a significant opportunity to reward
trucking fleets for their good practices while providing regulatory
flexibility to help address the great diversity of the heavy-duty
vehicle sector. It would not lead to any additional GHG reductions,
however, as the credits generated by the fleet operators would be used
by the engine or vehicle makers to comply with their standards. We
welcome comments on the merits and issues surrounding potential
approaches to credit operational and technical changes from heavy-duty
fleets to reduce GHG emissions.
    In considering the regulatory options available, we are cognizant
of the significant burden that could result if these programs were to
require testing of every potential engine and vehicle configuration
related to its GHG emissions. Therefore, we have been following efforts
in Japan to control GHG emissions through a regulatory program that
relies in part on engine test data and in part on vehicle modeling
simulation. As currently constructed, Japan's heavy-duty fuel
efficiency regulation considers engine fuel consumption, transmission
type, and final drive ratio in estimating overall GHG emissions. Such a
modeling approach may be a worthwhile first step and may be further
improved by including techniques to recognize design differences in
vehicle aerodynamics, tire rolling resistance, weight, and other
factors. We request comment on the appropriateness of combining
emissions test data with vehicle modeling results to quantify and
regulate GHG emissions. In particular, we welcome comments addressing
issues including model precision, equality aspects of model based
regulation, and the ability to standardize modeling inputs.
    The regulatory approaches that we have laid out in this section
reflect incremental steps along a potential path to fully address GHG
emissions from this sector. These approaches should not be viewed as
discrete options but rather as potential building blocks that could be
mixed and matched in an

overall control program. Given the potential for significant burden,
EPA is also interested in considering how flexibilities such as
averaging, banking, and/or credit trading that may help to reduce costs
may be built into any of the regulatory options discussed above. We
request comment on all of the approaches described in this section and
the potential to implement one or more of these approaches in a phased
manner to capture the more straightforward approaches in the near-term
and the more complex approaches over a longer period.
3. Highway Motorcycles
    The U.S. motorcycle fleet encompasses a vast array of types and
styles, from small and light scooters with chainsaw-sized engines to
large and heavy models with engines as big as those found in many
family sedans. In 2006 approximately 850,000 highway motorcycles were
sold in the U.S., reflecting a near-quadrupling of sales in the last
ten years. Even as motorcycles gain in popularity, their overall GHG
emissions remain a relatively small fraction of all mobile source GHG
emissions. Most motorcycles are used recreationally and not for daily
commuting, and use is seasonally limited in much of the country. For
these reasons and the fact that the fleet itself is relatively small,
total annual vehicle miles traveled for highway motorcycles is about
9.5 billion miles (as compared to roughly 1.6 trillion miles for
passenger cars).\161\
---------------------------------------------------------------------------

    \161\ ``Highway Statistics 2003,'' U.S. Department of
Transportation, Federal Highway Administration, Table VM-1, December
2004.
---------------------------------------------------------------------------

    The Federal Highway Administration reports that the average fuel
economy for motorcycles in 2003 was 50 mpg, almost twice that of
passenger cars in the same time frame. However, motorcycles are
generally designed and optimized to achieve maximum performance, not
maximum efficiency. As a result, many high-performance motorcycles have
fuel economy in the same range as many passenger cars despite the
smaller size and weight of motorcycles. Recent EPA emission regulations
are expected to reduce fuel use and hence GHG emissions from
motorcycles by: (1) Leading manufacturers to increase the use of
electronic fuel injection (replacing carburetors); (2) reducing
permeation from fuel lines and fuel tanks; and (3) eliminating the use
of two-stroke engines in the small scooter category.\162\
---------------------------------------------------------------------------

    \162\ See 69 FR 2398, January 15, 2004.
---------------------------------------------------------------------------

    There may be additional opportunities for further reductions in GHG
emissions. Options available to manufacturers may include incorporating
more precise feedback fuel controls; controlling enrichment on cold
starts and under load by electronically controlling choke operation;
allowing lower idle speeds when the opportunity exists; optimizing
spark for fuel and operating conditions through use of a knock sensor;
and, like light-duty vehicles, reducing the engine size and
incorporating a turbo-charger. The cost of these fuel saving and GHG
reducing technologies may be offset by the fuel savings realized over
the lifetime of the motorcycle.
    We request comment on information on what approaches EPA should
consider for potential further reductions in GHG emissions from
motorcycles. We also request comment and data regarding what
technologies may be applicable to achieve further GHG reductions from
motorcycles.

C. Nonroad Sector Sources

    As discussed previously, CAA section 213 provides broad authority
to regulate emissions from a wide array of nonroad engines and
vehicles,\163\ while CAA section 211 provides authority to regulate
fuels and fuel additives from both on-highway and nonroad sources and
CAA section 231 authorizes EPA to establish emissions standards for
aircraft. Collectively, the Title II nonroad and fuel regulation
programs developed by EPA over the past two decades provide a possible
model for how EPA could structure a long-term GHG reduction program for
nonroad engines and vehicles, fuels and aircraft.
---------------------------------------------------------------------------

    \163\ The Act does not define ``vehicle'', but we have
interpreted section 213 from its inception to include the broad
array of equipment, machines, and vessels powered by nonroad
engines, including those that are not self-propelled, such as
portable power generators. In keeping with common usage, we
typically use the generic terms ``equipment'', ``machine'', or
``application'', as well as the more application-specific terms
``vehicle'' and ``vessel'', to refer to these units, as appropriate.
---------------------------------------------------------------------------

    In this section, we first review and request comment on a number of
petitions received by EPA requesting action to regulate GHG emissions
from these sources and we highlight the similarities and key issues
raised in those petitions. We invite comment on all of the questions
and issues raised in these petitions. For each of three primary
groupings, nonroad, marine, and aircraft, we then discuss and seek
comment on the GHG emissions from these sources and the opportunities
to reduce GHG emissions through design and operational changes.
1. Petition Summaries
    Since the Massachusetts decision, EPA has received seven additional
petitions requesting that we make endangerment findings and undertake
rulemaking procedures using our authority under CAA sections 211, 213
and 231 to regulate GHG \164\ emissions from fuels, nonroad sources,
and aircraft. The petitioners represent states, local governments,
environmental groups, and nongovernmental organizations (NGO) including
the states of California, New Jersey, New Mexico, Friends of the Earth,
NRDC, OCEANA, International Center for Technology Assessment, City of
New York, and the South Coast Air Quality Management District. Copies
of these seven petitions can be found in the docket for this Advance
Notice. Following is a brief summary of these petitions. We request
comment on all issues raised by the petitioners.
---------------------------------------------------------------------------

    \164\ While petitioners vary somewhat in their definition of
GHGs, collectively they define carbon dioxide, methane, nitrous
oxide, hydrofluorocarbons, perfluorocarbons, water vapor, sulfur
hexaflouride, and soot or black carbon as GHGs.
---------------------------------------------------------------------------

a. Marine Engine and Vessel Petitions
    The Agency has received three petitions to reduce GHG emissions
from ocean-going vessels (OGVs). California submitted its petition on
October 3, 2007. A joint petition was filed on the same day by
EarthJustice on behalf of three environmental organizations: Oceana,
Friends of the Earth and the Center for Biological Diversity
(``Environmental Petitioners''). A third petition was received from the
South Coast Air Quality Management District (SCAQMD) on January 10,
2008.
    The California petition requests that EPA immediately begin the
process to regulate GHG emissions from Category 3 powered OGVs.\165\
According to the petition, the Governor of California has already
recognized that, ``California is particularly vulnerable to the impacts
of climate change,'' including the negative impact of increased
temperature on the Sierra snowpack, one of the State's primary sources
of water, and the further exacerbation of California's air quality
problems.\166\ The petition outlines the steps California has already
taken to reduce its own contributions to global warming and states that
it is petitioning the Administrator to take action to regulate GHG
emissions from

OGVs because it believes national controls will be most effective.
---------------------------------------------------------------------------

    \165\ A category 3 vessel is one where the main propulsion
engine(s) have a per-cylinder displacement of more than 30 liters.
    \166\ State of California, Petition for Rulemaking Seeking the
Regulation of Greenhouse Gas Emissions from Ocean--Going Vessels,
page3, October 3, 2007 (``California Petition'').
---------------------------------------------------------------------------

    California makes three key points in its petition. First,
California claims that EPA has clear authority to regulate OGV GHG
emissions under CAA section 213(a)(4). The State points out that the
``primary substantive difference'' between CAA section 202(a)(1), which
the Supreme Court found authorizes regulation of GHGs emissions from
new motor vehicles upon the Administrator making a positive
endangerment finding, and section 213 is that section 202(a)(1)
requires regulation if such an endangerment finding is made while
section 213(a)(4) authorizes, but does not require, EPA to regulate
upon making the requisite endangerment finding. But petitioner states
that EPA's discretion to decide whether to regulate OGVs under section
213(a)(4) is constrained in light of the overall structure and purpose
of the CAA. Citing the Massachusetts decision, California asserts that
the Supreme Court has ``set clear and narrow limits on the kinds of
reasons EPA may advance for declining to regulate significant sources
of GHGs''.
    The second claim California makes is that international law does
not bar regulation of GHG emissions from foreign-flagged vessels by the
U.S. California asserts that U.S. laws can operate beyond U.S. borders
(referred to as extra-territorial operation of laws) when the conduct
being regulated affects the U.S. and where Congress intended such
extra-territorial application.\167\ Petitioner believes that such
application of the CAA is both ``permissible and essential in this
case'' because to effectively control GHG emissions from shipping
vessels, the EPA must regulate foreign-flagged vessels since they
comprise 95% of the fleet calling on U.S. ports.\168\ Petitioner cites
two other instances where the U.S. has regulated foreign-flagged
vessels. First, in Specto v. Norwegian Cruiseline. 545 U.S. 119 (2005),
the Supreme Court held that the Americans with Disabilities Act (ADA)
could be applied to foreign-flagged cruise ships that sailed from U.S.
ports as long as the required accommodations for disabled passengers
did not require major, permanent modification to the ships involved.
Second, the National Park Service recently imposed air pollutant
emissions controls on cruise ships, including foreign-flagged cruise
ships that sail off the coast from Glacier Bay National Park, Alaska.
The petitioner points out that in this case they did so to protect and
preserve the natural resources of the Park, which is analogous to
California's reasons for why EPA must regulate GHG emissions from
foreign-flagged vessels.\169\
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    \167\ Petitioners cite EEOC v. Arabian American Oil Co., 499
U.S. 244 (1991) (``Aramco'') as supporting this principle.
    \168\ California Petition, page 13.
    \169\ Petitioners cite regulations found at 36 CFR 13.65 (b)(4)
and 61 FR 27008, at 27011.
---------------------------------------------------------------------------

    The third claim raised in California's petition is that technology
is currently available to reduce GHG emissions from these vessels,
either through NOX reductions or by reducing fuel
consumption. Options include, using marine diesel fuel oil instead of
bunker fuel, using selective catalytic reductions and exhaust gas
recirculation or by reducing speed. Petitioner states that the Clean
Air Act was intended to be a technology-forcing statute and that EPA
can and should consider OGV control measures that force the development
of new technology.
    California requests three forms of relief: (1) That EPA make a
finding that carbon dioxide emissions from new marine engines and
vessels significantly contribute to air pollution which may reasonably
be anticipated to endanger public health and welfare; (2) that EPA use
its CAA section 213(a)(4) authority to adopt regulations specifying
emissions standards for CO2 emissions from these engines and
vessels; and (3) that EPA adopt regulations specifying fuel content or
type necessary to carry out the emission standards adopted for new
marine engines.
    The second group requesting EPA action on OGVs, Environmental
Petitioners, believes that climate change threatens public health and
welfare and that marine shipping vessels make a significant
contribution to GHG emissions, and that therefore EPA should quickly
promulgate regulations requiring OGVs to meet emissions standards by
``operating in a fuel-efficient manner, using cleaner fuels and/or
employing technical controls, so as to reduce emissions of carbon
dioxide, nitrous oxide, and black carbon.'' These petitioners further
state that EPA should also control ``the manufacture and sale of fuels
used in marine shipping vessels by imposing fuel standards'' to reduce
GHG emissions.\170\
---------------------------------------------------------------------------

    \170\ Environmental Petition, Petition for Rulemaking Under the
Clean Air Act to Reduce the Emissions of Air Pollutants from Marine
Shipping Vessels that Contribute to Global Climate Change, page 2,
October 3, 2007.
---------------------------------------------------------------------------

    The Environmental Petitioners focus their petition on four specific
arguments. First, like California, they assert that OGVs play a
significant role in global climate change. They focus on the emissions
of four pollutants: CO2, NOX, N20, and
black carbon (also known as soot). Petitioners cite numerous studies
that they assert document that the impact of these GHG emissions are
significant today and that industry trends indicate these emissions
will grow substantially in future decades. Second, petitioners lay out
a detailed legal argument asserting that EPA has clear authority to
regulate these four air pollutants from OGVs, and contending that the
Massachusetts decision must guide EPA's actions as it decides how to
regulate GHG emissions from OGVs. Third, petitioners discuss a number
of regulatory measures that can effectively reduce GHG emissions from
OGVs and which EPA could adopt using its regulatory authority under CAA
section 213(a)(4), including measures requiring restrictions on vessel
speed; requiring the use of cleaner fuels in ships and other technical
and operations measures petitioners believe are relatively easy and
cost-effective. Lastly, petitioners assert that the CAA section 213
provides EPA with clear authority to regulate GHG emissions from both
new and remanufactured OGV engines as well as from foreign-flagged
vessels.
    SCAQMD petition also requests Agency action under section 213 of
the CAA and states that it has a strong interest in the regulation of
GHG emissions from ships including emissions of NOX, PM, and
CO2. SCAQMD states that the net global warming effect of
NOX emissions is potentially comparable to the climate
effect from ship CO2 emissions and that PM emissions from
ships in the form of black carbon can also increase climate
change.\171\ Finally, because international shipping activity is
increasing yearly, SCAQMD asserts that if EPA dos not act quickly,
future ship pollution will become even worse, increasing both ozone and
GHG levels in the South Coast area of California. As with other
petitioners, SCAQMD states that there is a clear legal basis for EPA to
regulate ships GHG emissions under section 213(a)(4).
---------------------------------------------------------------------------

    \171\ SCAQMD, Petition for Rulemaking under the Clean Air Act to
Reduce Global Warming Pollutants from Ships, page 2, January 10,
2008.
---------------------------------------------------------------------------

    SCAQMD makes two additional assertions in its petition which mirror
the California and Environmental Petitions. First, EPA can avoid
regulation of ship GHG emissions only if it determines that
``endangerment'' can be avoided without regulation of ship
emissions.\172\ Second, SCAQMD believes that EPA has the authority to
regulate foreign-flagged vessels under at

least two circumstances: (1) For a foreign owned and operated vessel,
where the regulation(s) would not interfere with matters that ``involve
only the internal order and discipline of the vessel,'' Spector v.
Norwegian Cruise Lines, 545 U.S. 119, 131 (2005), and (2) where the
vessel is owned and operated by a U.S. corporation, even if it is
foreign-flagged.\173\
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    \172\ SCAQMD Petition, page 9.
    \173\ SCAQMD Petition, page10.
---------------------------------------------------------------------------

    SCAQMD requests two types of relief: (1) That EPA, within six
months of receiving its petition, make a positive endangerment
determine for CO2, NOX, and black carbon
emissions from new marine engines and vessels ``because of their
contribution to climate change;'' and (2) that EPA promulgate
regulations under CAA section 213 (a)(4) to obtain the maximum feasible
reductions in emissions of these pollutants. We invite comment on all
elements of the petitioners' assertions and requests.
b. Aircraft Petitions
    The Agency has received two petitions to reduce GHG emissions from
aircraft.\174\ The first petition was submitted on December 4, 2007, by
California, Connecticut, New Jersey, New Mexico, Pennsylvania's
Department of Environmental Protection, the City of New York, the
District of Columbia, and the SCAQMD (``State Petitioners''). A second
petition was filed on December 31, 2007, by Earthjustice on behalf of
four environmental organizations: Friends of the Earth, Oceana, Center
for Biological Diversity and NRDC (``Environmental Petitioners'').
---------------------------------------------------------------------------

    \174\ While aircraft engines are not ``nonroad engines'' as
defined in CAA section 216(10) and aircraft are not ``nonroad
vehicles'' as defined in CAA section 216(11), such that aircraft
could be subject to regulation under CAA section 213, for
organizational efficiency we include aircraft in this ``Nonroad
Sector Sources'' section of today's notice.
---------------------------------------------------------------------------

    All petitioners request that EPA exercise its authority under
section 231(a) of the CAA to regulate GHG emissions from new and
existing aircraft and/or aircraft engine operations, after finding that
aircraft GHG emissions cause or contribute to air pollution which may
reasonably be anticipated to endanger public health or welfare.\175\
Petitioners suggest that these regulations could allow compliance
through technological controls, operational measures, emissions fees,
or a cap-and-trade system.
---------------------------------------------------------------------------

    \175\ Petitioners maintain that aircraft engine emissions of
CO2, NOX, water vapor, carbon monoxide, oxides
of sulfur, and other trace components including hydrocarbons such as
methane and soot contribute to global warming and that in 2005,
aircraft made up 3% of U.S. CO2 emissions from all
sectors, and 12% of such emissions from the transportation sector.
States of California et al, Petition for Rulemaking Seeking the
Regulation of Greenhouse Gas Emissions from Aircraft, page 11,
December 4, 2007, and Friends of the Earth et al., Petition for
Rulemaking under the Clean Air Act to Reduce the Emissions of Air
Pollutants from Aircraft that Contribute to Global Climate Change,
pages 6-7, December 31, 2007.
---------------------------------------------------------------------------

    Both petitions discuss how aircraft engines emit GHG emissions
which they assert have a disproportionate impact on climate change.
Petitioners cite a range of scientific documents to support their
statements. They assert that ground-level aircraft NOX, a
compound they identify as a GHG, contributes to the formation of ozone,
a relatively short-lived GHG. NOX emissions in the upper
troposphere and tropopause, where most aircraft emissions occur, result
in greater concentrations of ozone in those regions of the atmosphere
compared to ground level ozone formed as a result of ground level
aircraft NOX emissions. Petitioners contend that aircraft
emissions contribute to climate change also by modifying cloud cover
patterns. Aircraft engines emit water vapor, which petitioners identify
as a GHG that can form condensation trails, or ``contrails,'' when
released at high altitude. Contrails are visible line shaped clouds
composed of ice crystals that form in cold, humid atmospheres.
Persistent contrails often evolve and spread into extensive cirrus
cloud cover that is indistinguishable from naturally occurring cirrus
clouds. The petitioners state that over the long term this contributes
to climate change.
    State Petitioners highlight the effects climate change will have in
California and the City of New York as well as efforts underway in both
places to reduce GHG emissions. They argue that without federal
government regulation of GHG emissions from aircraft, their efforts at
mitigation and adaptation will be undermined. Both petitioners urge
quick action by EPA to regulate aircraft GHG emissions since these
emissions are anticipated to increase considerably in the coming
decades due to a projected growth in air transport both in the United
States and worldwide. They cite numerous reports to support this point,
including an FAA report, which indicates that by 2025 emissions of
CO2 and NOX from domestic aircraft are expected
to increase by 60%.\176\
---------------------------------------------------------------------------

    \176\ FAA, Office of Environment and Energy, Aviation and
Emission: A Primer, January 2005, page 10, available at http://
www.faa.gov/regulations_policies/policy_guidance/envir_policy/
media/aeprimer.pdf.
---------------------------------------------------------------------------

    We request comment on all issues raised in the petitions,
particularly on two assertions made by Environmental Petitioners: (1)
That technology is available to reduce GHG emissions from aircraft
allowing EPA to take swift action, and (2) that EPA has a mandatory
duty to control GHG emissions from aircraft and can fulfill this duty
consistent with international law governing aircraft. In addition, we
invite comment on the petitioners' assessment of the impact of aircraft
GHG emissions on climate change, including the scientific understanding
of these impacts, and whether aircraft GHG emissions cause or
contribute to air pollution which may reasonably be anticipated to
endanger public health or welfare.
    With regard to technology, petitioners highlight existing and
developing aviation procedures and technologies which could reduce GHG
emissions from new and existing aircraft. For example, they point to
various aviation operations and procedures including minimizing engine
idling time on runways and employing single engine taxiing that could
be undertaken by aircraft to reduce GHG emissions. Petitioners also
discuss the availability of more efficient aircraft designs to reduce
GHG emissions, such as reducing their weight, and they suggest that
using alternative fuels could also reduce aviation GHG emissions.
    Environmental Petitioners contend that once EPA makes a positive
endangerment finding for aircraft GHG emissions, EPA has a mandatory
duty to act, but that the potential regulatory responses available to
EPA are quite broad and should be considered for all classes of
aircraft, including both new and in-use aircraft and aircraft engines.
In addition, petitioners argue that EPA's authority to address GHG
emissions from aircraft is consistent with international law-in
particular the Convention on International Civil Aviation (the
``Chicago Convention'')--and that the United States'' obligations under
the Convention do not constrain EPA's authority to adopt a program that
addresses aviation's climate change impacts, including those from
foreign aircraft.
    The State and Environmental Petitioners each request the following
relief: (1) That EPA make an explicit finding under CAA section
231(a)(2)(A) that GHG emissions from aircraft cause or contribute to
air pollution which may reasonably be anticipated to endanger public
health or welfare; (2) that EPA propose and adopt standards for GHG
emissions from both new and in-use aircraft as soon as possible; (3)
that EPA adopt regulations that allow a range of compliance approaches,
including emissions limits, operations practices and/or fees, a cap-
and-trade system, as well as measures that are more near-

term, such as reduced taxi time or use of ground-side electricity
measures. The Environmental Petitioners' also request that EPA issue
standards 90 days after proposal. We invite comment on all elements of
the petitioners' assertions and requests, as well as the scientific and
technical basis for their assertions and requests.
c. Nonroad Engine and Vehicle Petitions
    On January 29, 2008, EPA received two petitions to reduce GHG
emissions from nonroad engines and vehicles. The first petition was
submitted by California, Connecticut, Massachusetts, New Jersey and
Oregon and Pennsylvania's Department of Environmental Protection
(``State Petitioners''). The second petition was submitted by the
Western Environmental Law Center on behalf of three nongovernmental
organizations: the International Center for Technology Assessment,
Center for Food Safety, and Friends of the Earth (``NGO Petitioners'').
    Both petitions request that EPA exercise its authority under CAA
section 213(a)(4) to adopt emissions standards to control and limit GHG
emissions from new nonroad engines excluding aircraft and vessels. Both
petitions seek EPA regulatory action on a wide range of nonroad engines
and equipment, which the petitioners believe, contribute substantially
to GHG emissions, including outdoor power equipment, recreational
vehicles, farm and construction machinery, lawn and garden equipment,
logging equipment and marine vessels.\177\
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    \177\ The two petitions request that EPA regulate slightly
different categories of nonroad engines and vehicles under CAA
section 213. State Petitioners exclude from their request aircraft,
locomotives and ocean-going vessels and do not include rebuilt
heavy-duty engines. The NGO Petitioners exclude only aircraft and
ocean-going vessels but also request that EPA use its CAA section
202 authority to regulate GHG emissions from rebuilt heavy-duty
engines.
---------------------------------------------------------------------------

    The State Petitioners, mirroring the earlier State petitions on
ocean-going vessels and aircraft, describe the harms which they believe
will occur due to climate change, including reduced water supplies,
increased wildfires, and threats to agricultural outputs in California;
loss of coastal wetlands, beach erosion, saltwater intrusion of
drinking water in Massachusetts and Connecticut; and similar harms to
the Pennsylvania, New Jersey and Oregon. The petition highlights
actions that California has already taken to reduce its own
contributions to global warming but points out that only EPA has
authority to regulate emissions from new farm and construction
equipment under 175 horsepower, ``which constitutes a sizeable portion
of all engines in this category.* * * '' \178\
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    \178\ States Petition for Nonroad, page 7-8.
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    The State Petitioners present three claims which, they believe
compel EPA action to reduce GHG emissions from nonroad sources. First,
petitioners claim that GHG emissions from these sources are
significant.\179\ Petitioners cite various reports documenting national
GHG emissions from a broad range of nonroad categories which, they
contend, provide evidence that nonroad GHG emissions are already
substantial, and will continue to increase in the future. Petitioners,
also cite additional inventory reports that nonroad GHG emissions
already exceed total U.S. GHG emissions from aircraft as well as from
boats and ships, rail, and pipelines combined.\180\ Petitioner's
present California nonroad GHG emissions data which, they contend,
mirror national GHG emission trends for nonroad engines and bolster
their claim that GHG emissions from the nonroad sector, as a whole, are
significant and are substantial for three categories: Construction and
mining equipment, agricultural, and industrial equipment.
---------------------------------------------------------------------------

    \179\ Petitioners indicate that in 2007, non-transportation
mobile vehicles and equipment were responsible for approximately 220
million tons of CO2 emissions (data derived from EPA's
Nonroad Emissions model for 2007). State of California et al,
Petition for Rulemaking Seeking the Regulation of Greenhouse Gas
Emissions from Nonroad Vehicles and Engines, page 8, January 29,
2008, and International Center for Technology Assessment et al,
Petition for Rulemaking Seeking the Regulation of Greenhouse Gas
Emissions from Nonroad Vehicles and Engines, page 5, January 29,
2008.
    \180\ State Petition for Nonroad, page 9.
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    State Petitioners' second claim is that EPA has the authority to
regulate GHG emissions from nonroad sources, although they acknowledge
that CAA section 213(a)(4) is discretionary. Petitioners contend this
discretion is not unlimited and that the structure of the CAA must
guide EPA's actions. Petitioners maintain that since the CAA prohibits
States from undertaking their traditional police power role in
regulating pollution from new construction or agricultural sources
under 175 horsepower, ``Congress has implicitly invested EPA with the
responsibility to act to prevent [these] harmful emissions.'' The third
and final claim raised by State Petitioners is that both physical and
operational controls are currently available to achieve fuel savings
and/or to limit GHG emissions. Such measures include idle reduction,
electrification of vehicles, the use of hybrid or hydraulic-hybrid
technology, as well as use of ``cool paints'' that reduce the need for
air conditioning.
    NGO petitioners make three similar claims in their petition. First,
petitioners argue that serious public health and environmental
consequences are projected for this century unless effective and timely
action is taken to mitigate climate change. Petitioners further contend
that GHG emissions from nonroad engines and vehicles are responsible
for a significant and growing amount of GHG emissions and, like the
State petitioners previously, they highlight three nonroad sectors
responsible for a large portion of these GHG emission--construction,
mining, and agriculture.
    Petitioners' second claim is that once EPA renders a positive
endangerment determination under CAA section 202 for motor vehicles and
engines, this finding should also satisfy the endangerment
determination required under CAA section 213(a)(4) for nonroad engines.
EPA's discretion under CAA section 213(a)(4) is limited, petitioners
assert, by the relevant statutory considerations, as held by the
Supreme Court in Massachusetts v. EPA, so that the Agency ``can decline
to regulate nonroad engine and vehicle emissions only if EPA determines
reasonably that such emissions do not endanger public health or
welfare, or else, taking into account factors such as cost, noise,
safety and energy, no such regulations would be appropriate.'' \181\
Like State petitioners, NGOs point out that because the CAA restricts
states' ability to regulate pollution from new construction or farm
vehicles and engines under 175 horsepower, Congress ``implicitly
invested EPA with unique responsibility to act in the states'' stead so
as to prevent such harmful emissions.'' Petitioners also argue that the
National Environment Policy Act (NEPA) section 101(b) compels EPA
action to fulfill its duty ``as a trustee of the environment for
succeeding generations.''
---------------------------------------------------------------------------

    \181\ NGO Petition, page 8.
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    NGO Petitioners' third claim is that a wide range of technology is
currently available to reduce GHG emissions from nonroad engines and
vehicles and that, in addition, the CAA was intended to be a
technology-forcing statute so that EPA ``can and should'' establish
regulations that ``substantially limit GHG emissions.* * * even where
those regulations force the development of new technology.'' Regarding
technology availability, petitioners provide a list of technologies
that they believe are currently available to reduce GHG emissions from
nonroad vehicles and engines, including auxiliary power unit systems to
avoid engine use solely to

heat or cool the cab; tire inflation systems; anti-idling standards;
use of hybrid or hydraulic-hybrid technology; use of low carbon fuels;
and use of low viscosity lubricants.
    Both State and NGO Petitioners request three types of relief: (1)
That EPA make a positive endangerment determination for GHG emissions
from nonroad vehicles and engines; \182\ (2) that EPA adopt regulations
to reduce GHG emissions from this sector; and (3) that regulations
necessary to carry out the emissions standards also be adopted.\183\ We
invite comment on all of the petitioners' assertions and requests.
---------------------------------------------------------------------------

    \182\ In addition, NGO Petitioners also request that EPA make a
determination under CAA section 202 (a)(3)(D) that GHG emissions
from rebuilt heavy-duty engines also are significant contributors to
air pollution which may reasonably be anticipated to endanger public
health and welfare. NGO Petition, page 11.
    \183\ State Petitioners indicate that adopting regulations
specifying fuel type, for example, may be necessary to carry out the
emission limitations.
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2. Nonroad Engines and Vehicles
    In this section, we discuss the GHG emissions and reduction
technologies that are or may be available for the various nonroad
engines and vehicles that are the subject of the petitioners described
above. Since section 213 was added to the CAA in 1990, the Agency has
completed a dozen major rulemakings which established programs that
reduce traditional air pollutants from nonroad sources by over 95%,
benefitting local, regional, and national air quality. EPA's approach
has been to set standards based on technology innovation, with
flexibility for the regulated industries to meet environmental goals
through continued innovation that can be integrated with marketing
plans.
    With help from industry, environmental groups and state regulators,
EPA has designed nonroad regulatory programs that have resulted in
significant air quality gains with little sacrifice of products'
ability to serve their purpose. In fact, manufacturers have generally
added new features and performance improvements that are highly
desirable to users. Because GHG reductions from nonroad sources can be
derived from fuel use reductions that directly benefit the user's
bottom line, we expect that manufacturers' incentive to increase the
fuel efficiency of their products will be even stronger in the future.
This potential appears higher for nonroad engines compared to highway
engines because in the past energy consumption has been less of a focus
in the nonroad sector, so there may be more opportunity for
improvement, while at the same time higher fuel prices are now
beginning to make fuel expenses more important to potential equipment
purchasers.
    The Agency and regulated industries have in the past grouped
nonroad engines in a number of ways. The first is by combustion cycle,
with two primary cycles in use: compression-ignition (CI) and spark-
ignition (SI). The combustion cycle is closely linked to grouping by
fuel type, because CI engines largely burn diesel fuel while SI engines
burn gasoline or, for forklifts and other indoor equipment, liquefied
petroleum gas (LPG). It has also been useful to group nonroad engines
by application category. Regulating nonroad engine application
categories separately has helped the Agency create effective control
programs, due to the nonroad sector's tremendous diversity in engine
types and sizes, equipment packaging constraints, affected industries,
and control technology opportunities. Although for the sake of
discussion we use these application groupings, we solicit comment on
what grouping engines and applications would make the most sense for
GHG regulation, especially if flexible emissions credit and averaging
concepts are pursued across diverse applications.
a. Nonroad Engine and Vehicle GHG Emissions
    Nonroad engines emitted 249 million metric tons of CO2
in 2006, 12% of the total mobile source CO2 emissions.\184\
CO2 emissions from the nonroad sector are expected to
increase significantly in the future, approximately 46% between 2006
and 2030. Diesel engines emit 71% of the total nonroad CO2
emissions. The other 29% comes from gasoline, LPG, and some natural
gas-fueled engines. CO2 emissions from individual nonroad
application categories in decreasing order of prominence are: Nonroad
diesel (such as farm tractors, construction and mining equipment),
diesel locomotives, small SI (such as lawn mowers, string trimmers, and
portable power generators), large SI (such as forklifts and some
construction machines), recreational marine SI, and recreational
offroad SI (such as all terrain vehicles and snowmobiles).
---------------------------------------------------------------------------

    \184\ Emissions data in this section are from Inventory of U.S.
Greenhouse Gas Emissions and Sinks: 1990-2006. EPA 430-R-08-005.
April 2008, and EPA NONROAD2005a model.
---------------------------------------------------------------------------

    GHG emissions from nonroad applications are dominated by
CO2 emissions which comprise approximately 97% of the total.
Approximately 3% of the GHG emissions (on a CO2 equivalent
basis) from nonroad applications are due to hydrofluorocarbon
emissions, mainly from refrigerated rail transport. Methane and
N2O make up less than 0.2% of the nonroad sector GHG
emissions on a CO2 equivalent basis. Much of the following
discussion focuses on technology opportunities for CO2
reduction, but we note that these technologies will generally reduce
N2O and methane emissions as well, and we ask for comment on
measures and options for specifically addressing N2O and
methane emissions.
b. Potential for GHG Reductions From Nonroad Engines and Vehicles
    The opportunity for GHG reductions from the nonroad sector closely
parallels the highway sector, especially for the heavy-duty highway and
nonroad engines that share many design characteristics. In addition,
there is potential for significant further GHG reductions from changes
to vehicle and equipment characteristics. A range of GHG reduction
opportunities is summarized in the following discussion. Comment is
requested on these opportunities and on additional suggestions for
reducing GHGs from nonroad sources.
    It should be noted that any means of reducing the energy
requirements necessary to power a nonroad application can yield the
desired proportional reductions of GHGs (and other pollutants as well).
Although in past programs, the Agency has typically focused on a new
engine's emissions per unit of work, such as gram/brake horsepower-hour
(g/bhp-hr), it may prove more effective to achieve GHG reductions by
redesigning the equipment or vehicle that the engine powers so that the
nonroad application accomplishes its task while expending less energy.
Improvements such as these do not show up in measured g/bhp-hr
emissions levels, but would be reflected in some other metric such as
grams emitted by a locomotive in moving a ton of freight one mile.
    EPA solicits comment on possible nonroad GHG emissions reduction
strategies for the various ``pathways'' by which GHGs can be impacted.
Although it is obvious that internal combustion engines emit GHGs via
the engine exhaust, it is helpful to take the analysis to another level
by putting it in the context of energy use and examining the pathways
by which energy is expended in a nonroad application, such as through
vehicle braking. Because of the diversity of nonroad applications, we
are taking a different approach here than in other sections of this
notice: first, we summarize some of the engine, equipment, and
operational pathways

and opportunities for GHG reductions that are common to all or at least
a large number of nonroad applications; next, we examine more closely
just one of the hundreds of nonroad applications, locomotives, to
illustrate the many additional application-specific pathways for GHG
reductions that are available. Our assessment is that, despite the
great diversity in nonroad applications, technology-based solutions
exist for every application to achieve cost-effective and substantial
GHG emissions reductions.
i. Common GHG Reduction Pathways
    To ensure that this advance notice initiates the widest possible
discussion of potential GHG control solutions, the following discussion
includes all three types of possible control measures: engine,
equipment, and operational.
(1) Engine Pathways
    To date, improving fuel usage in many nonroad applications has not
been of great concern to equipment users and therefore to designers.
There is potential for technologies now fairly commonplace in the
highway sector, such as advanced lubricants and greater use of
electronic controls, to become part of an overall strategy for GHG
emissions reduction in the nonroad sector. We welcome comment on the
opportunities and limitations of doing so.
    One engine technology in particular warrants further discussion.
Two-stroke gasoline engines have been popular especially in handheld
lawn care applications and recreational vehicles because they are
fairly light and inexpensive. However, they also produce more GHGs than
four-stroke engines. Much progress has been made in recent years in the
development of four-stroke engines that function well in these
applications. We ask for comment on the extent to which a shift to
four-stroke engines would be feasible and beneficial.
    Although today's nonroad gasoline and diesel engines produce
significantly less GHGs than earlier models, further improvements are
possible. Engine designers are continuing to work on new designs
incorporating technologies that produce less GHGs, such as homogeneous
charge CI, waste heat recovery through turbo compounding, and direct
fuel injection in SI engines. Most of this work has already been done
for the automotive sector where economies of scale can justify the
large investments. Much of this innovation can eventually be adapted to
nonroad applications, as has occurred in the past with such
technologies as electronic fuel injection and common rail fueling. We
therefore request comment on the feasibility and potential for these
advanced highway sector technologies, discussed in section VI.B, to be
introduced or accelerated in the nonroad sector.
(2) Equipment and Operational Pathways
    Technology solutions in both the equipment design and operations
can reach beyond the engine improvements to further reduce GHG
emissions. We broadly discuss the following technologies below:
Regenerative energy recovery and hybrid power trains, CVT
transmissions, air conditioning improvements, component design
improvements, new lighting technologies, reduced idling, and consumer
awareness.
    Locomotives, as an example, have significant potential to recover
energy otherwise dissipated as heat during braking. An 8,000-ton coal
train descending through 5,000 feet of elevation converts 30 MW-hrs of
potential energy to frictional and dynamic braking energy. Storing that
energy on board quickly enough to keep up with the energy generation
rate presents a challenge, but may provide a major viable GHG emissions
reduction strategy even if only partially effective. Another
regenerative opportunity relates to the specific, repetitive,
predictable work tasks that many nonroad machines perform. For example,
a forklift in a warehouse may lift a heavy load to a shelf and in doing
so expend work. Just as often, the forklift will lower such a load from
the shelf, and recover that load's potential energy, if a means is
provided to store that energy on board.
    There are, however, many nonroad applications that may not have
much potential for regenerative energy recovery (a road grader, for
example), but in those applications a hybrid diesel-electric or diesel-
hydraulic system without a regenerative component may still provide
some GHG benefits. A machine that today is made with a large engine to
handle occasional peak work loads could potentially be redesigned with
a smaller engine and battery combination sized to handle the occasional
peak loads.
    Besides pre-existing electrical or hydraulic systems, some nonroad
applications have one additional advantage over highway vehicles in
assessing hybrid prospects: They often have quite predictable load
patterns. A hybrid locomotive, for example, can be assigned to
particular routes, train sizes, and consist (multi-locomotive) teams,
to ensure it is used as close to full capacity as possible. The space
needs of large battery banks could potentially be accommodated on a
tender car, and the added weight would be offset somewhat by a smaller
diesel fuel load (typically 35,000 lbs today) and dynamic brake grid.
At least one locomotive manufacturer, General Electric, is already
developing a hybrid design, and battery energy storage has been
demonstrated for several years in rail yard switcher applications.
    We request comment on all aspects of the hybrid and regeneration
opportunity in the nonroad sector, including the extent to which the
electric and hydraulic systems already designed into many nonroad
machines and vehicles could provide some cost savings in implementing
this technology, and the extent to which plug-in technologies could be
used in applications that have very predictable downtime such as
overnight at construction sites, or that can use plug-in electric power
while working or while sitting idle between tasks.
    A Continuously Variable Transmission (CVT) has an advantage over
other conventional transmission designs by allowing the engine to
operate at its optimum speed over a range of vehicle speeds and
typically over a wider range of available ratios, which can provide GHG
emission reductions. It has been estimated that CVTs can provide a 3 to
8% decrease in fuel use over 4-speed automatic transmissions.\185\ They
are already in use some in nonroad vehicles such as snowmobiles and
all-terrain vehicles, and could possibly be used in other nonroad
applications as well. We request comment on the opportunities to apply
CVT to various nonroad applications.
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    \185\ ``Effectiveness and Impact of Corporate Average Fuel
Economy (CAFE) Standards,'' National Research Council, National
Academy of Sciences, 2002.
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    Some nonroad applications have air conditioning or refrigeration
equipment, including large farm tractors, highway truck transport
refrigeration units (TRUs), locomotives, and refrigerated rail cars.
Reducing refrigerant leakage in the field or reducing its release
during maintenance would work to reduce GHG emissions In addition, a
switch to refrigerants with lower GHG emissions than the currently-used
fluorinated gases can have a significant impact. We expect that the
measures used to reduce nonroad equipment refrigerant GHGs would most
likely involve the same strategies that have been or could be pursued
in the highway and stationary

source sectors, and the reader is referred to section VI.B.1 for
additional discussion. We request comment on the degree to which
nonroad applications emit fluorinated gases, and on measures that may
be taken to reduce these emissions.
    An extensive variety of energy-consuming electrical, mechanical,
and hydraulic accessories are designed into nonroad machines to help
them perform their tasks. Much of the energy output of a nonroad engine
passes through these components and systems in making the machine do
useful work, and all of them have associated energy losses through
bearing friction, component heating, and other pathways. Designing
equipment to use components with lower GHG impacts in these systems can
yield substantial overall reductions in GHG emissions.
    Some nonroad applications expend significant energy in providing
light, such as locomotive headlights and other train lighting.
Furthermore, diesel-powered portable light towers for highway
construction activities at night are increasingly being used to reduce
congestion from daytime lane closures. We request comment on the extent
to which a switch to less energy-intensive lighting could reduce GHG
emissions.
    Many nonroad diesel engines are left idling during periods when no
work is demanded of them, generally as a convenience to the operator,
though modern diesel engines are usually easy to restart. In some
applications this may occupy hours every day. Even though the hourly
fuel rate is fairly low during idle, in the past several years
railroads have saved considerable money by adding automatic engine stop
start (AESS) systems to locomotives. These monitor key parameters such
as state of battery charge, and restart the engine only as needed,
thereby largely eliminating unnecessary idling. They reduce GHG
emissions and typically pay for themselves in fuel savings within a
couple of years. Our recent locomotive rule mandated these systems for
all new locomotives as an emission control measure (40 CFR
1033.115(g)). AESS or similar measures may be feasible for other
nonroad applications with significant idling time as well. We request
comment on the availability and effectiveness of nonroad idle reduction
technologies.
ii. Application-Specific GHG Pathways
    As mentioned above, we discuss application-specific approach for
further reducting GHG emissions from one nonroad application,
locomotives, to illustrate application-specific opportunities for GHG
emission reductions beyond those discussed above that apply more
generally. We note that some of these application-specific
opportunities, though limited in breadth, may be among the most
important, because of their large GHG reduction potential.
    We have chosen locomotives for this illustration in part because
rail transportation has already been the focus of substantial efforts
to reduce its energy use, resulting in generally favorable GHG
emissions per ton-mile or per passenger-mile. The Association of
American Railroads calculates that railroads move a ton of freight 423
miles on one gallon of diesel fuel.\186\ Reasons for the advantage
provided by rail include the use of medium-speed diesel engines, lower
steel-on-steel rolling resistance, and relatively gradual roadway
grades. Rail therefore warrants attention in any discussion on mode-
shifting as a GHG strategy. Even if GHG emissions reduction were not at
issue, shippers and travelers already experience substantial mode-shift
pressure today from long-term high fuel prices. Growth in the rail
sector highlights the critical importance of locomotive GHG emissions
reduction.
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    \186\ Comments of the Association of American Railroads on EPA's
locomotive and marine engine proposal, July 2, 2007. Available in
EPA docket EPA-HQ-OAR-2003-0190.
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    We have listed some key locomotive-specific opportunities below. We
note that a number of these are aimed at addressing GHG pathways from
rail cars. Rail cars create very significant GHG reduction pathways for
locomotives, because all of the very large energy losses from railcar
components translate directly into locomotive fuel use. This is
especially important when one considers that an average train has
several dozen cars. We request comment on the feasibility of the ideas
on this list and on other possible ways to reduce GHG emissions.
Opportunities for Rail GHG Reduction
Locomotives
     Low-friction wheel bearings
     Aerodynamic improvements
     Idle emissions control beyond AESS (such as auxiliary
power units)
     Electronically-controlled pneumatic (ECP) brakes
     High-adhesion trucks (wheel assemblies)
     Global positioning system (GPS)-based speed management (to
minimize braking, over-accelerations, and run-out/run-in losses at
couplings)
Railcars
     Low-torque rail car wheel bearings
     Tare weight reduction
     Aerodynamic design of rail cars and between-car gaps
     Better insulated refrigeration cars
Rail Infrastructure
     Application of lubricants or friction modifiers to
minimize wheel-to-track friction losses
     Higher-speed railroad crossings
     Targeted-route electrification
     Rail yard infrastructure improvements to eliminate
congestion and idling
Operational
     Consist manager (automated throttling of each locomotive
in a consist team for lowest overall GHG emissions)
     Optimized GPS-assisted dispatching/routing/tracking of
rail cars and locomotives
     Optimized matching of locomotives with train load for
every route (including optimized placement of each locomotive along the
train)
     Expanded resource sharing among railroads
     Reduction of empty-car trips
     Early scrappage of higher-GHG locomotives
c. Regulatory Options for Nonroad Engines and Vehicles
    There is a range of options that could be pursued under CAA section
213 to control nonroad sector GHGs. The large diversity in this sector
allows for a great number of technology solutions as discussed above,
while also presenting some unique challenges in developing a
comprehensive, balanced, and effective regulatory program, and
highlights the importance of considering multiple potential regulatory
strategies. We have met similar challenges in regulating traditional
air pollutants from this sector, and we request comment on the
regulatory approaches discussed below and whether they would address
the challenges of regulating GHGs from nonroad engines.
    As discussed in our earlier section on heavy-duty vehicles, the
potential regulatory approaches that we discuss here should be
considered not as discrete options but as a continuum of possible
approaches to address GHG emissions from this sector. Just as we have
in our technology discussion, these regulatory approaches begin with
the engine and then expand to included potential approaches to realize
reductions through vehicle and operational changes. In approaching the
discussion in this way, each step along such a path has the potential
to greater regulatory complexity but also has the

potential for greater regulatory flexibility, GHG reduction, and
program benefits. For large GHG reductions in the long term we expect
to give consideration to approaches that accomplish the largest
reductions, but we also note that, given the long time horizons for GHG
issues, we can consider a number of incremental regulatory steps along
a longer path. Also, given the absence of localized effects associated
with GHG emissions, EPA is interested in considering the incorporation
of banking, averaging, and/or credit trading into the regulatory
options discussed below.
    The first regulatory approach we consider is a relatively
straightforward extension of our existing criteria pollutant program
for nonroad engines. In its simplest form, this approach would be an
engine GHG standard that preserves the current regulatory structure for
nonroad engines. Nonroad engine manufacturers are already familiar with
today's certification testing and procedures. Just like the highway
engine manufacturers, they have facilities, engine dynamometers, and
test equipment to appropriately measure GHG emissions. Further,
technologies developed to reduce GHG emissions from heavy-duty engines
could be applied to the majority of diesel nonroad engines with
additional development to address differences in operating conditions
and engine applications in nonroad equipment. Hence, this approach
would benefit from both regulatory work done to develop a heavy-duty
engine GHG program and technology development for heavy-duty engines to
comply with a GHG program. While we do not expect that new test cycles
would be needed to effect meaningful GHG emissions control, we request
comment on whether new test cycles would allow for improved control,
and especially on whether there are worthwhile GHG control technologies
that would not be adequately exercised and measured under the current
engine test cycles and test procedures.
    A second approach that would extend control opportunities beyond
engine design improvements involves developing nonroad vehicle and
equipment GHG standards. Changes to nonroad vehicles and equipment can
offer significant opportunity for GHG emission reductions, and
therefore any nonroad GHG program considered by EPA would need to
evaluate the potential for reductions not just from engine changes but
from vehicle and equipment changes as well. In section VI.B.2 we
discussed a potential heavy-duty truck GHG standard (e.g., a gram per
mile or gram per ton-mile standard). A similar option could be
considered for at least some portion of nonroad vehicles and equipment.
For example, a freight locomotive GHG standard could be considered on a
similar mass per ton mile basis. This would be a change from our
current mass per unit work approach to locomotive regulation, but
section 213 of the Clean Air Act does authorize the Agency to set
vehicle-based and equipment-based nonroad standards as well.
    However, we are concerned that there may be significant drawbacks
to widespread adoption of this application-specific standards-setting
approach. For the freight locomotive example given above, a gram per
ton-mile emissions standard measured over a designated track route
might be a suitable way to express a GHG standard, but such a metric
would not necessarily be appropriate for other applications. Instead
each application could require a different unit of measure tied to the
machine's mission or output-- such as grams per kilogram of cuttings
from a ``standard'' lawn for lawnmowers and grams per kilogram-meter of
load lift for forklifts. Such application-specific standards would
provide the clearest metric for GHG emission reductions. The standards
would directly reflect the intended use of the equipment and would help
drive equipment and engine designs that most effectively meet that need
while reducing overall GHG emissions. However, the diversity of tasks
performed by the hundreds of nonroad applications would lead to a
diverse array of standard work units and measurement techniques in such
a nonroad GHG program built on equipment-based standards. We request
comments on this second regulatory approach, and in particular comments
that identify specific nonroad applications that would be best served
by such a nonroad vehicle-based regulatory approach.
    A variation on the above-described approaches would be to maintain
the relative simplicity of an engine-based standard while crediting the
GHG emission reduction potential of new equipment designs. Under this
option, the new technology would be evaluated by measuring GHG
emissions from a piece of equipment that has the new technology while
performing a standard set of typical tasks. The results would then be
compared with data from the same or an identical piece of equipment,
without the new technology, performing the same tasks. This approach
could be carried out for a range of equipment models to help improve
the statistical case for the resulting reductions. The percentage
reduction in GHG emissions with and without the new equipment
technology could then be applied to the GHG emissions measured in
certification testing of engines used in the equipment in helping to
demonstrate compliance with an engine-based GHG standard. Thus if a new
technology were shown to reduce the GHG emissions of a typical piece of
equipment by 20%, that 20% reduction could be applied at certification
to the GHG emission results from a more traditional engine-based test
procedure and engine-based standard.
    In fact, a very similar approach has been adopted in EPA's recently
established locomotive program (see 73 FR 25155, May 6, 2008). In this
provision, credit is given to energy-saving measures based on the fact
that they provide proportional reductions in the criteria pollutants.
This credit takes the form of an adjustment to criteria pollutant
emissions measured under the prescribed test procedure for assessing
compliance with engine-based standards.
    A more flexible extension of this approach would be to de-link the
equipment-based GHG reduction from the compliance demonstration for the
particular engine used in the same equipment. Instead the GHG
difference would provide fungible credits for each piece of equipment
sold with the new technology, credits that then could be used in a
credit averaging and trading program. Under this concept it would be
important to collect and properly weight data over an adequate range of
equipment and engine models, tasks performed, and operating conditions,
to ensure the credits are deserved. We request comments on the option
of applying the results of equipment testing to an engine-based GHG
standard and the more general concept of generating GHG emission
credits from such an approach. We also request comment on whether such
credit-based approaches to accounting for the many promising equipment
measures are likely to obtain similar GHG reductions as the setting of
equipment based standards, and on whether some combined approach
involving both standards and credits may be appropriate.
    There are also a number of ways to reduce GHG emissions in the
nonroad sector that do not involve engine or equipment redesign.
Rather, reductions can be achieved by altering the way in which the
equipment is used. For example, intermodal shipping moving freight from
trucks and onto lower GHG rail or marine services, provides a means of
reducing these emissions for

freight shipments that can accommodate the logistical constraints of
intermodal shipping. Many of the operational measures with GHG-reducing
potential do involve a significant technology component, perhaps even
hardware changes, but they can also involve actions on the part of the
equipment operator or owner that go beyond simply maintaining and not
tampering with the emission controls. For example, a railroad may make
the capital and operational investment in sophisticated computer
technology to dispatch and schedule locomotive resources, using onboard
GPS-based tracking hardware. The GHG reduction benefit, though enabled
in part by the onboard hardware, is not realized without the people and
equipment assigned to the dispatch center.
    Credit for such operational measures could conceivably be part of a
nonroad GHG control program and could be calculated and assigned using
the same ``with and without'' approach to credit generation described
above for equipment-based changes. However, some important
implementation problems arise from the greater human element involved.
This human element becomes increasingly significant as the scope of
creditable measures moves further away from automatic technology-based
solutions. Assigning credits to such measures must involve good
correlation between the credits generated and the GHG reductions
achieved in real world applications. It therefore may make sense to
award these credits only after an operational measure has been
implemented and verified as effective. This might necessitate that such
credits have value for equipment or sources other than the equipment
associated with the earning of the credit, such as in a broader credit
market. This is because nonroad equipment and engines must demonstrate
compliance with EPA standards before they are put into service. They
therefore cannot benefit from credits created in the future unless
through some sort of credit borrowing mechanism.
    Once verified, however, we would expect credits reflecting these
operational reductions could be banked, averaged and traded, just as
much as credits derived from equipment- or engine-based measures.
Verifiable GHG reductions, regardless of how generated, have equal
value in addressing climate change. We also note, however, that an
effective credit program, especially one with cross-sector utility,
should account for the degree to which a credit-generating measure
would have happened anyway, or would have happened eventually, had no
EPA program existed; this is likely to be challenging. We request
comment on the appropriateness of a much broader GHG credit-based
program as described here.
    In this section, we have laid out a range of regulatory approaches
for nonroad equipment that takes us from a relatively simple extension
of our existing engine-based regulatory program through equipment based
standards and finally to a fairly wide open credit scheme that would in
concept at least have the potential to pull in all aspects of nonroad
equipment design and operation. In describing these approaches, we have
noted the increasing complexity and the greater need for new mechanisms
to ensure the emission reductions anticipated are real and verifiable.
We seek comment on the relative merits of each of these approaches but
also on the potential for each approach along the continuum to build
upon the others.
3. Marine Vessels
    Marine diesel engines range from very small engines used to propel
sailboats, or used for auxiliary power, to large propulsion engines on
ocean-going vessels. Our current marine diesel engine emission control
programs distinguish between five kinds of marine diesel engines,
defined in terms of displacement per cylinder. These five types include
small (<=37 kW), recreational, and commercial marine engines.
Commercial marine engines are divided into three categories based on
per cylinder displacement: Category 1 engines are less than 5 l/cyl,
Category 2 engines are from 5 l/cyl up to 30 l/cyl, and Category 3
engines are at or above 30 l/cyl. Category 3 engines are 2- or 4-stroke
propulsion engines that typically use residual fuel; this fuel has high
energy content but also has very high fuel sulfur levels that result in
high PM emissions. Most of the other engine types are 4-stroke and can
be used to provide propulsion or auxiliary power. These operate on
distillate fuel although some may operate on a blend of distillate and
residual fuel or even on residual fuel (for example, fuels commonly
known as DMB, DMC, RMA, and RMB).
    There are also a wide variety of vessels that use marine diesel
engines and they can be distinguished based on where they are used.
Vessels used on inland waterways and coastal routes include fishing
vessels that may be used either seasonally or throughout the year,
river and harbor tug boats, towboats, short- and long-distance ferries,
and offshore supply and crew boats. These vessels often have Category 2
or smaller engines and operate in distillate fuels. Ocean-going vessels
(OGVs) include container ships, bulk carriers, tankers, and passenger
vessels and have Category 3 propulsion engines as well as some smaller
auxiliary engines. As EPA deliberates on how to potentially address GHG
emissions from marine vessels, we will consider the significance of the
different engine, vessel, and fuel types. We invite comment on the
marine specific issues that EPA should consider; in particular, we
invite commenters to compare and contrast potential marine vessel
solutions to our earlier discussions of highway and nonroad mobile
sources and our existing marine engine criteria pollutant control
programs.
a. Marine Vessel GHG Emissions
    Marine engines and vessels emitted 84.2 million metric tons of
CO2 in 2006, or 3.9 percent of the total mobile source
CO2 emissions. CO2 emissions from marine vessels
are expected to increase significantly in the future, more than
doubling between 2006 and 2030. The emissions inventory from marine
vessels comes from operation in ports, inland waterways, and offshore.
The CO2 inventory estimates presented here refer to
emissions from marine engine operation with fuel purchased in the
United States.\187\ OGVs departing U.S. ports with international
destinations take on fuel that emits 66 percent of the marine vessel
CO2 emissions; the other 34 percent comes from smaller
commercial and recreational vessels.
---------------------------------------------------------------------------

    \187\ U.S. EPA, ``Inventory of U.S. Greenhouse Gas Emissions and
Sinks: 1990-2006,'' April 15, 2008.
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    GHG emissions from marine vessels are dominated by CO2
emissions which comprise approximately 94 percent of the total.
Approximately 5.5 percent of the GHG emissions from marine vessels are
due to HFC emissions, mainly from reefer vessels (vessels which carry
refrigerated containers). Methane and nitrous oxide make up less than 1
percent of the marine vessel sector GHG emissions on a CO2
equivalent basis. Comment is requested on the contribution of marine
vessels to GHG emissions and on projections for growth in this sector.
b. Potential for GHG Reductions From Marine Vessels
    There are significant opportunities to reduce GHG emissions from
marine vessels through both traditional and innovative strategies.
These strategies include technological improvements to engine and
vessel design as well as changes in vessel operation. This

section provides an overview of these strategies, and a more detailed
description is available in the public docket.\188\ EPA requests
comment on the advantages and drawbacks of each of the strategies
described below, as well as on additional approaches for reducing
greenhouse gases from marine vessels.
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    \188\ ``Potential Technologies for GHG Reductions from
Commercial Marine Vessels'', memorandum from Michael J. Samulski,
U.S. EPA, to docket xx, DATE.
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i. Reducing GHG Emissions Through Marine Engine Changes
    GHG emissions may be reduced by increasing the efficiency of the
marine engine. As discussed earlier for heavy-duty trucks, there are a
number of improvements for CI engines that may be used to lower GHGs.
These improvements include higher compression ratios, higher injection
pressure, shorter injection periods, improved turbocharging, and
electronic fuel and air management. Much of the energy produced in a CI
engine is lost to the exhaust. Some of this energy can be reclaimed
through the use of heat recovery systems. We request comment on the
feasibility of reducing GHG emissions through better engine designs and
on additional technology which could be used to achieve GHG reductions.
    As discussed above, marine engines are already subject to exhaust
emission standards. Many of the noxious emissions emitted by internal
combustion engines may also be GHGs. These pollutants include
NOX, methane, and black carbon soot. Additionally, some
strategies used to mitigate NOX and PM emissions can also
indirectly impact GHGs through their impact on fuel use--for example,
use of aftertreatment rather than injection timing retard to reduce
NOX emissions. We request comment on the GHG reductions
associated with HC+NOX and PM emissions standards for these
engines.
    The majority of OGVs operate primarily on residual fuel, while
smaller coastal vessels operate primarily on distillate fuel. Shifting
more shipping operation away from residual fuel would reduce GHG
emissions from the ship due to the lower carbon/hydrogen ratio in
distillate fuel. Marine engines have been developed that operate on
other lower carbon fuels such as natural gas and biodiesel. Because
biodiesel is a renewable fuel, lifecycle GHG emissions are much lower
than for operation on petroleum diesel. We request comment on these and
other fuels that may be used to power marine vessels and the impact
these fuels would have on lifecycle GHG emissions.
    A number of innovative alternatives are under development for
providing power on marine vessels. These alternative power sources
include fuel cells, solar power, wind power, and even wave power. While
none of these technologies are currently able to supply the total power
demands of larger, ocean-going vessels, they may prove to be capable of
reducing GHG emissions through auxiliary power or power-assist
applications. Hybrid engine designs are used in some vessels where a
bank of engines is used to drive electric motors for power generation.
The advantage of this approach is that the same engines may be used
both for propulsion and auxiliary needs. Another advantage is that
alternative power sources could be used with a hybrid system to provide
supplemental power. We request comment on the extent to which
alternative power sources and hybrid designs may be applied to marine
vessels to reduce greenhouse gases.
ii. Reducing GHG Emissions Through Vessel Changes
    GHG emissions may be reduced by minimizing the power needed by the
vessels to perform its functions. The largest power demand is generally
for overcoming resistance as the vessel moves through the water but is
also affected by propeller efficiency and auxiliary power needs.
    Water resistance is made up of the effort to displace water and
drag due to friction on the hull. The geometry of the vessel may be
optimized in many ways to reduce water resistance. Ship designers have
used technologies such as bulbous bows and stern flaps to help reduce
water resistance from the hull of the vessel. Marine vessels typically
use surface coatings to inhibit the growth of barnacles or other sea
life that would increase drag on the hull. Innovative strategies for
reducing hull friction include coatings with textures similar to marine
animals and reducing water/hull contact by enveloping the hull with
small air bubbles released from the sides and bottom of the ship.
    Both the wetted surface area and amount of water displaced by the
hull may be reduced by lowering the weight of the vessel. This may be
accomplished through the use of lower weight materials such as aluminum
or fiberglass composites or by simply using less ballast in the ship
when not carrying cargo. Other options include ballast-free ship
designs such as constantly flowing water through a series of pipes
below the waterline or a pentamaran hull design in which the ship is
constructed with a narrow hull and four sponsons which provide
stability and eliminate the need for ballast water. We request comment
to the extent that these approaches may be used to reduce GHGs by
reducing fuel consumption from marine vessels in the future. We also
request comment on other design changes that may reduce the power
demand due to resistance on the vessel.
    In conventional propeller designs, a number of factors must be
considered including load, speed, pitch, diameter, pressure pulses, and
cavitation (formation of bubbles which may damage propeller and reduce