Alternative Fuels Strategies

An alternative fuel, most generally defined, is any fuel other than the traditional selections, gasoline and diesel, used to produce energy or power. The emissions impact and energy output provided by alternative fuels varies, depending on the fuel source. Examples of alternative fuels include biodiesel, ethanol, electricity, propane, compressed natural gas, and hydrogen.

Definitions of Alternative Fuels

Alternative fuels being used in transportation are briefly described below.

Biodiesel is a clean burning, renewable alternative fuel that can be produced from a wide range of vegetable oils and animal fats. Biodiesel contains no petroleum, but can be blended at any level with petroleum diesel to create a biodiesel blend. It can be used in compression-ignition (diesel) engines with little or no modifications.

Ethanol is a renewable alternative biofuel made from various plant materials. Ethanol can be blended with gasoline in varying quantities; most spark-ignited gasoline-style engines will operate well with mixtures of 10 percent ethanol (E10). E85, a mixture of 85 percent ethanol and 15 percent unleaded gasoline, is an alternative fuel for use in flexible fuel vehicles (FFVs).

Electricity used to power vehicles is provided by the electricity grid and stored in the vehicle's batteries. Vehicles that run on electricity have no tailpipe emissions. Electric vehicles are not currently available from the major auto manufacturers; most electric vehicles have been converted by amateur mechanics.

Propane, also known as liquefied petroleum gas, is a by-product of natural gas processing and crude oil refining. Propane is less toxic than other fuels. It has a high octane rating and excellent properties for spark-ignited internal combustion engines. Currently, less than 2 percent of U.S. propane consumption is used for transportation; however, interest is growing due to its domestic availability, high energy density, and clean-burning qualities.

Compressed Natural Gas (CNG) is a natural gas that is extracted from wells and compressed. Natural gas is a fossil fuel comprised mostly of methane and is cleaner burning than gasoline or diesel fuel. Natural gas vehicles have been found to produce less greenhouse gas emissions than gasoline vehicles, but very little natural gas consumption is currently used for transportation fuel.

Hydrogen (H2) is a renewable, domestically-produced, alternative fuel that can be used to create electricity. A chemical reaction between oxygen and hydrogen produces the electric power, and when the transportation fuel is pure hydrogen, the only resulting emission is water vapor. Depending on the energy source that causes the chemical reaction, hydrogen can be an emission-free transportation fuel. Not widely used today, current government and industry research and development are investigating safe and

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