Question

What is biomass? Explain the principle and working of a biogas plant using a labeled schematic diagram.

Answer 1

Biomass:

1. The term biomass refers to fuel sources derived from organic material.
2. Cow dung and various plant materials such as crop residue, vegetable waste, and sewage are decomposed in the absence of oxygen to produce biogas.

Principle and working of a biogas plant:

1. The plant is built with bricks and has a dome-like structure.
2. The mixing tank creates a slurry of cow dung and water, which is then fed into the digester.
3. The digester is a vacuum-sealed chamber with no oxygen. Anaerobic microorganisms that do not require oxygen decompose or break down complex cow-dung slurry compounds.
4. The decomposition process takes a few days to complete and produces gases such as methane, carbon dioxide, hydrogen, and hydrogen sulfide.
5. The biogas is stored in a gas tank above the digester and drawn through pipes for use.
6. Biogas is an excellent fuel because it contains up to 75% methane. It produces no smoke and leaves no residue, unlike ash or charcoal.

A diagram of the biogas plant is given below: