Biogas is mainly produced after the                                               of the organic materials. It is principally a mixture of carbon dioxide and methane, along with other trace gases. Since the bigogas produced is very rich in methane, it is easy to recover through the use of mechanical biological treatment systems. Normally, Biogas is produced in natural enviornments that are low in oxygen and have degradable organic matter present. These natural sources of biogas include: wet soils, animal and insect digestive tracks, core of some trees, aquatic sediments, and buried organic matter. There are additional human-made sources of biogas, including waste lagoons, landfills, and waste storage structures. Due to methane’s potent greenhouse gas properties, atmospheric emissions of biogas contribute to climate change. Biogas can also be produced with the biodegradation of waste materials which are fed into anaerobic digesters which yields biogas. The residue or the by product can be easily used as manure or fertilizers for agricultural use. The biogas produced is very rich in methane which can be easily recovered through the use of mechanical biological treatment systems. A less clean form of biogas is the landfill gas which is produced by the use of naturally occurring anaerobic digesters."Biogas, like natural gas, has a low volumetric energy density compared to the liquid biofuels, ethanol and biodiesel.  However, biogas may be purified to a natural gas equivalent fuel for pipeline injection and further compressed for use as a transportation fuel.  Methane, the principal component in biogas, has four times the volumetric energy density of hydrogen (H2) and is suitable for use in many types of fuel cell generators."