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What is Biogas?


Biogas is a renewable and environmentally benign energy source. It is produced anaerobically, when organic matter, such as food or animal waste, is broken down by microbes in the absence of oxygen. To accomplish this, the waste material must be enclosed in an atmosphere devoid of oxygen. Biogas can be produced either organically or through an industrial process for use as a fuel.

Working of Biogas Plant

The mixing tank is where the biomass and water are mixed together to make a slurry. A slurry is made up of water and cow manure (biomass). The slurry is then put into the digester. The digester is an airtight chamber where there is no oxygen (basically an anaerobic area) and microorganisms live (the anaerobic bacteria). These microorganisms in the digester break down the biomass, or organic matter, into simple chemicals like methane, hydrogen, carbon dioxide, and hydrogen sulphide. The gases that are made are stored in the gas tank and taken out through the gas outlet when they are needed. In addition to gas, products like manure and fertilisers are also made when biomass breaks down.


Methane (CH4), found in natural gas, and carbon dioxide make up the majority of biogas . Raw (untreated) biogas may contain between 40% and 60% methane, with the majority of the remaining gas being CO2 and trace amounts of other gases and water vapour. Like natural gas, biogas can be used directly as a fuel or treated to remove the CO2 and other gases. Biomethane or renewable natural gas are two names for treated biogas.

Advantages of Biogas

  • Non-polluting: As biogas burns without emitting smoke, it releases no polluting gases such as CO2, CO, NO2, and SO2.

  • Non-Toxic Residue: The sludge produced by biogas production can be used as fertiliser in fields. A variety of biogas residues (BGRs) have been used as organic fertilizer in agriculture. The use of these residues affects the storage of soil organic matter (SOM). It enhances soil fertility and is easy on farmer’s pocket.

  • Affordable technology: A Biogas plant requires no significant installation costs and can become self-sufficient within three to four months.

Disadvantages of Biogas

In addition to its many advantages, biogas also has certain downsides. They are listed below:

1)Cannot be used on large scale: Since it is difficult to increase the efficiency of biogas on a large scale, it is not economically possible to use biogas on a large scale.

2)Has contaminants: It contains a great deal of impurities that are difficult to eliminate even multiple purification cycles. When biogas is compressed for use as fuel, it is extremely corrosive to the container.

3)Unstable and dangerous: When methane reacts violently with oxygen, it produces carbon dioxide. As a result, methane's highly flammable nature makes it prone to explosions.


Global warming is getting real with each passing day. Alarming the policy makers, environmentalists and scientists all over the world. There is a need to switch to cleaner fuels to stop this menace.

Biogas is one of the best alternatives today as it is not only eco friendly, it also fulfils the energy need and resolves another big problem of waste management.

Particularly for farmers, it has shown to be of enormous benefit. They can use the residue as fertiliser to improve yield and fertility. Rural communities could become energy self-sufficient with the use of biogas.


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