Alternative fuels are defined by the U.S. Department of Energy based on guidelines formed in the Energy Policy Act of 1992. Alternative fuels are those which are substantially nonpetroleum, yield substantial energy security benefits, and offer substantial environmental benefits.
The following are the approved alternative fuels:
- Methanol, ethanol, and other alcohols
- Blends of 85% or more of alcohol with gasoline
- Natural gas and liquid fuels domestically produced from natural gas
- Liquefied petroleum gas (propane)
- Coal-derived liquid fuels
- Fuels (other than alcohol) derived from biological materials