BIOGAS

Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Biogas originates from biogenic material and is a type of biofuel.
One type of biogas is produced by anaerobic digestion or fermentation of biodegradable materials such as biomass, manure or sewage, municipal waste, green waste and energy crops[This type of biogas comprises primarily methane and carbon dioxide. The other principal type of biogas is wood gas which is created by gasification of wood or other biomass. This type of biogas is comprised primarily of nitrogen, hydrogen, and carbon monoxide, with trace amounts of methane.
The gases methane, hydrogen and carbon monoxide can be combusted or oxidized with oxygen. Air contains 21% oxygen. This energy release allows biogas to be used as a fuel. Biogas can be used as a low-cost fuel in any country for any heating purpose, such as cooking. It can also be used in modern waste management facilities where it can be used to run any type of heat engine, to generate either mechanical or electrical power. Biogas can be compressed, much like natural gas, and used to power motor vehicles and in the UK for example is estimated to have the potential to replace around 17% of vehicle fuel [2]. Biogas is a renewable fuel, so it qualifies for renewable energy subsidies in some parts of the world.Once upgraded to the required level of purity (and compressed or liquefied), biogas can be used as an alternative vehicle fuel in the same forms as conventionally derived natural gas .A 2007 report estimated that 12,000 vehicles are being fueled with upgraded biogas worldwide, with 70,000 biogas-fueled vehicles predicted by 2010. Europe has most of these vehicles. Sweden alone reports that more than half of the gas used in its 11,500 natural gas vehicles is biogas. Germany and Austria have established targets of 20% biogas in natural gas vehicle fuel. For more information on Europe's biogas vehicle activities, see the papers Biogas Upgrading and Utilization as Vehicle Fuel and The Future of Biogas in Europe: Visions and Targets until 2020 , which are part of the proceedings The Future of Biogas in Europe III
In the United States, biogas vehicle activities have been on a smaller scale. Examples include a landfill in Whittier, California, that fuels vehicles with CNG derived from the landfill and an Orange County, California, landfill that produces LNG for use in transit buses. Several DOE-sponsored projects also have developed biogas vehicle technologies .