Environmental Engineering Reference
In-Depth Information
13
There is no separate fuel cycle for fuels used in transportation or for electricity transmission.
Transportation and electricity transmission are part of several fuel cycles for energy technolo-
gies described in
previous chapters.
The environmental, dollar, and national security costs of
transportation of fuels and electric power transmission must be considered as additional to the
costs of utilizing each energy fuel technology. That is, transportation and transmission costs are
in addition to generation costs for each energy technology that involves conversion of a fuel to
electricity and each fuel that requires transportation from its location of production to its location
of end use. Transportation of energy fuels to the point of their end use adds dollar costs to the price
of each fuel, compared to what it would be priced at for consumption at the point of production.
Consumption of energy fuels near their point of origin would be less expensive.
Transportation deserves special treatment because mobility imposes limitations on what fuels
can be used for it. Many fuels cannot be used for transportation until they are converted to an-
other form, such as a storable liquid or electricity. For example, coal was used to power trains
and ships at one time and could still be used now, but it is not used in that manner today because
diesel fuel is easier to handle. Synthetic liquid fuels from coal could be used in transportation
vehicles today, but they are more expensive than petroleum fuels. The principal limiting factor
concerning energy use in transportation is that the energy source must be amenable to storage
onboard the conveyance in sufficient quantities to get to the next fueling station, at a competitive
price. Nuclear, solar, wind, geothermal, hydro, and ocean energy technologies cannot be used for
transportation unless converted to electricity, and then their energy must be stored in batteries
carried on each vehicle.
Petroleum, natural gas, and liquids or gases from renewable resources are the principal fuels
used in transportation. Seventy-one percent of the petroleum consumed in the United States in
2010 was used in transportation by automobiles and motorcycles, light-duty trucks (minivans,
pickup trucks, sport utility vehicles), heavy-duty trucks, and buses. Petroleum accounted for 94
percent of all energy used in transportation, with 2 percent coming from natural gas and 4 percent
from renewable energy sources, principally biomass fuels such as ethanol blended with gasoline
(Davis, Diegel, and Boundy 2011, Figure 2.0).
In the United States there are over 4 million miles of public roads (USDOT 2011, Table 1.11),
and energy fuels are transported over many of them in bulk every day. Over 254 million cars, buses,
and trucks traveling U.S. roads (USDOT 2011, Table 1.11) are the main reason for the country's
reliance on foreign oil (Sperling and Cannon 2004, 1). Although there has been discussion for
many years about the utility of electric vehicles, and 2012 will see the Chevrolet Volt, the first
commercially available all-electric car since they went out of fashion in the 1930s (Bellis 2011),
electric cars and electricity currently provide a minuscule portion of our transportation needs.
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