Transportation's Role in Reducing U.S. Greenhouse Gas Emissions ...

Transportation's Role in Reducing U.S. Greenhouse Gas Emissions: Volume 1
duty vehicles in 2030 . 102 On the other hand, if higher fuel prices are
sustained over time (either because of market forces, or because of dramatic
fuel or carbon tax increases) the additional benefit of technology standards
would be lessened. Furthermore, economy-wide pricing would have impacts
on other modes (albeit quite modest, at fuel price levels predicted under cap
and trade proposals—see Section 4.1) that are not affected by energy
efficiency regulations. An increase in the price of fuel or carbon would also
have the effect of shifting vehicle purchases between segments of the lightduty
vehicle market, i.e., from light trucks to cars, as was seen when gas
prices spiked in 2008 and sales of SUVs dropped while demand for fuel
efficient cars rose. CAFE standards may or may not have this effect.
Separate standards for light trucks and cars could decrease purchase shifts.
However, some manufacturers significantly discount fuel efficient models in
order shift more of their sales to these models and meet CAFE standards.
• Some vehicle and fuel strategies are interrelated. Only a few fuels—notably,
biodiesel and ethanol at blends of 10 to 15 percent or less—can be used
directly in today’s vehicles without modification. Most low-carbon fuels
such as higher ethanol blends or natural gas, require at least minor
modifications to vehicle design. Some, notably electricity and hydrogen,
benefit from or require the development of entirely new vehicle propulsion
technologies.
103
Furthermore, the total benefits cited for fuel efficiency and
low-carbon fuel strategies are not additive. To determine the total benefits
from these strategies, it would be necessary to construct scenarios of future
market penetration for different vehicle and fuel technology combinations.
From a policy perspective, the Federal government can play an important
role in ensuring that research and development activities, regulations, and
infrastructure deployment are coordinated to promote a complementary set
of vehicle and fuel technologies.
• As vehicle efficiency increases and/or fuel carbon content decreases, the
absolute GHG reduction benefits of system efficiency and travel activity
strategies (such as signal coordination, pricing, land use, and transit) will
decrease proportionately. Furthermore, some vehicle technologies will
reduce the benefits from system efficiency strategies aimed at addressing
congestion or idling, as GHG emissions associated with congestion or idling
are minimized through the use of fuel cell, electric, and hybrid electric-
102 U.S. Department of Energy, Energy Information Administration (2008). “Energy
Market and Economic Impacts of S. 2191, the Lieberman-Warner Climate Security Act
of 2007.”
103 In addition, diesel vehicles – treated as a vehicle technology strategy in this report –
could easily be considered a fuel strategy; and plug-in hybrid vehicles, also treated in
vehicle technology, also make use of electricity as a fuel source and share many of the
same characteristics as battery-electric vehicles.
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