Alternative fuel is defined as sustainable fuel Here are some examples:

  • Compressed natural gas (CNG) which is natural gas compressed to a volume and density that is practical as a portable fuel supply (even when compressed, natural gas is not a liquid).
  • Ethanol (C2H5OH): is otherwise known as ethyl alcohol, alcohol, or grain -spirit. A clear, colorless, flammable oxygenated hydrocarbon with a boiling point of 78.5 degrees Celsius in the anhydrous state. It is used in the United States as a gasoline octane enhancer and oxygenate (10 percent concentration). Ethanol can also be used in high concentrations in vehicles optimized for its use. 
  • Liquefied Natural Gas (LNG): Natural gas that has been refrigerated to temperatures at which it exists in a liquid state. 
  • Liquefied petroleum gases (LPG) are propane, propylene, normal butane , butylene, isobutane, and isobutylene produced at refineries or natural gas processing plants (includes plants that fractionate raw natural gas plant liquids). 
  • Methanol (CH3OH) is a colorless liquid with essentially no odor and very little taste. The simplest alcohol, it boils at 64.7 degrees Celsius. It is miscible with water and most organic liquids (including gasoline) and is extremely flammable, burning with a nearly invisible blue flame. Methanol is produced commercially by the catalyzed reaction of hydrogen and carbon monoxide. It was formerly derived from the destructive distillation of wood, which caused it to be known as wood alcohol.