What is Biogas?


Biogas is generated through anaerobic digestion of organic waste. Anaerobic digestion is a biological process making it possible to degrade organic matter by producing biogas which is a renewable energy source and the sludge can be used as fertilizer.

The production of biogas is carried out in a natural way. Variety of organic wastes like vegetable, fruits, food wastes, industrial wastes from process industries and sewage sludge can be used as feedstock for biogas generation. In the absence of oxygen (anaerobic digestion), the organic matter is degraded partially by the combined action of several types of micro-organisms. A succession of biological reactions led to the formation of biogas and sludge. The bacteria which carry out these reactions exist in natural state in the liquid manure and the anaerobic ecosystems; it is not normally necessary to add more, they develop naturally in a medium without oxygen.

Typical biogas composition is as follows, 55-60 % of CH4, 30-35 % of CO2, 3-4 % of H2S and 1-2% moisture. Raw biogas can be upgraded to BioCNG also called as compressed biogas (CBG) by applying suitable upgrading technology. The biogas once upgraded will have CH4 >95% and CO2 <5%, which can be used as vehicle fuel or for various industrial process. The upgraded biogas is equivalent to quality of CNG and can be used in similar applications where natural gas is currently being used. Upgraded biogas can also be fed directly in to national gas grid.

Biogas an all-rounder

Biogas is the only renewable energy source which can be used for various applications. Raw biogas can be used for following applications.

  1. Stream generation , biogas can be fired in boilers for stream generation
  2. Power generation by using CHP Engines (Combined Heat and Power Engines). H2S levels in biogas are brought down to less than 200 ppm before injecting in to the engines. C02 scrubbing is not required for power generation.
  3. BioCNG generation by purifying H2S and CO2 present in raw biogas. Methane CH4 purity required is above 97 % for BioCNG generation.
  4. BioLNG is generated by liquefying biogas by using cryogenic technology. Liquefied biogas can be easily transported once the gas is liquefied.