Biofuel is any gas or liquid fuel that derives either from recently living organisms or their metabolic byproducts, such as manure from cows. It is a renewable energy, unlike nuclearfossil sources (petroleum, coal and nuclear energy).
Ethanol (not produced from petroleum) - A significant amount of ethanol produced from sugar beets is being used as automotive fuel in Brazil. Ethanol produced from corn (maize) is being used as a gasoline additive (oxygenator) in the United States.
Methanol - Currently, methanol is produced from natural gas. It is possible, but not economically viable at anywhere near current price levels, to produce methanol from biomass (biomethanol).
Biodiesel - obtained from animal fats and vegetable oil (vegoils), using transesterification. Properly processed biodiesel is satisfactory for use in diesel cars.
Methane - Methane produced by the nature decay of garbage at garbage dumps is collected and used in place of fossil methane. Methane from manure decay is sometimes collected for use as fuel.