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

� 2.1 Summary
Overview of Low-Carbon Fuel Options
Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
Fuels used for transportation in the United States are almost entirely derived from liquid
fossil fuel. Petroleum-based fuels make up about 97 percent of transportation energy use,
and refined petroleum products such as gasoline, jet fuel, and diesel make up more than 90
percent of this consumption. In particular, petroleum-based gasoline represents about 60
percent of all energy consumption in the transportation sector, followed by distillates
(diesel) at 22 percent, and jet fuel at 11 percent (U.S. DOE, 2009a). An additional three
percent is used in for the form of residual fuel oil, mostly for marine applications.
The current dominance of petroleum-based fuels reflects the inherent advantages of liquid
fuels for transportation, with their high energy densities allowing for extended vehicle
range on limited storage. Gasoline and diesel in particular also benefit from their firmly
established production and distribution infrastructures, resulting in price advantages and
creating significant barriers to entry for most alternatives.
Nevertheless, there are many alternative liquid and nonliquid fuels in various stages of
development that can be used to reduce the GHG emissions associated with conventional
petroleum-based fuels. The following provides a brief overview of the alternative fuels
that could be used to replace conventional gasoline, diesel, and marine distillate in the
transportation sector. The potential use of each fuel by mode is summarized in Table 2.1.
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