Biogas is produced by anaerobic digestion or fermentation or decomposition of organic wastes by the action of methanogenic bacteria. It is composed of 50-70% methane, 30-45% carbon dioxide, 1% H2S, 0.1%N2, 0.1% O2, 0.1% H2 and some other gases. During digestion about 25-30 % of the dry matter of waste is converted into a combustible gas and residue of 70-75 % of the total solids content comes out as sludge which is known as slurry. The energy content of biogas is 6-6.5 KWh/m3, and the ignition temperature is 650-750 o C.
Technology and Mechanism
This energy allows biogas to be used as a fuel for any heating purpose, such as cooking. It can also be used in a gas engine to convert the energy in the gas into electricity. Biogas can be compressed, much like natural gas and used to power motor vehicles. This gas is about 20 percent lighter than the air which is odorless and burns with clear blue flame similar to that of Liquefied Petroleum Gas (LPG).