Heavy-Vehicle
Technologies and Fuels
Various alternative fuels and improved engine and vehicle systems have been
proposed to reduce emissions and energy use associated with heavy vehicles (predominantly
trucks). For example, oil companies have proposed improved methods for converting
natural gas to zero-aromatics, zero-sulfur diesel fuel via the Fischer-Tropsch
(F-T) process. Major heavy-duty diesel engine companies are working on ways to
simultaneously reduce particulate matter and NOx emissions. The trend
in heavy vehicles is toward use of lightweight materials, tires with lower rolling
resistance, and treatments to reduce aerodynamic drag. At the same time, efforts have increased to reduce the amount of time that trucks idle their engines while parked.
Argonne compared the life-cycle energy use and emissions from Class-8 tractor-semitrailer
combination trucks using selected alternatives, such as Fisher-Tropsch diesel
fuel and advanced fuel-efficient engines. The total life-cycle includes production
and recycling of the vehicle itself; extraction, processing, and transportation
of the fuel itself; and vehicle operation and maintenance. Total energy use is
considered as well as those portions that are imported, domestic, and renewable.
The impacts of vehicle production, fuel production, and vehicle operation were
assessed. For most cases, the vehicle operation dominates energy consumption and
emissions. Engine and vehicle system improvements contribute equally to fuel savings
and emissions reduction. However, fuel production may also be important.
The findings suggest that the use of natural-gas-based alternative fuels in
trucks neither saves energy nor minimizes greenhouse gas (GHG) emissions, but
it does minimize petroleum consumption. GHG emissions for trucks using any fuel
could be reduced most effectively by improving truck engine and drivetrain efficiency
and aerodynamics and by reducing rolling resistance and weight. Improved F-T processes
being developed by fuels producers could possibly result in lower GHG emissions
over the total life cycle, compared with liquefied natural gas, but reliable data
are unavailable. Natural gas would appear more attractive if a more efficient
engine were developed.
Publications
- Technology Options to Reduce Truck Idling, by L. Gaines et al. [306 kB pdf]
- Life-Cycle Analysis for Heavy Vehicles, by L. Gaines et al. [131 kB pdf]
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