Liquid

There are also a number of liquid forms of biomass that can be used as a fuel:
• Bioalcohols — see alcohol as a fuel.
o Ethanol produced from sugar cane is being used as automotive fuel in Brazil. Ethanol produced from corn is being used as a gasoline additive (oxygenator) in the United States.
o Methanol, which is currently produced from natural gas, can also be produced from biomass — although this is not economically viable at present. The methanol economy is an interesting alternative to the hydrogen economy.
o Butanol is formed by A.B.E. fermentation (Acetone, Butanol Ethanol). It can be burned "straight" in existing gasoline engines, produces more energy and is less corrosive and less water soluble than ethanol, and can distributed via existing infrastructures.
• Biologically produced oils (bio-oils) can be used in diesel engines :
o Straight vegetable oil (SVO).
o Waste vegetable oil (WVO).
o Biodiesel obtained from transesterification of animal fats and vegetable oil, directly usable in petroleum diesel engines.
• Oils and gases can be produced from various wastes:
o Thermal depolymerization can extract methane and oil similar to petroleum from waste.
o Methane and oils are being extracted from landfill wells and leachate in test sites.

Gaseous
• Bio-methane produced by the natural decay of garbage or agricultural manure can be collected for use as fuel.
o It is also possible to estimate the number of animals needed for desirable size of biogas driven engine with Biogas Calculator
• Wood gas can be extracted from wood and used in petrol engines.
• Hydrogen can be produced in water electrolysis or, less ecologically, by cracking any hydrocarbon fuel in a reformer.
• Gasification, that produces carbon monoxide.

Other
One company, GreenFuel Technologies Corporation, has developed a patented bioreactor system that utilizes nontoxic photosynthetic algae to take in smokestacks flue gases and produce biofuels such as biodiesel, bio-gas (similar to natural gas), and a dry fuel comparable to coal. Coal is a black mineral made by fire.