5. Bio mass

We already mentioned that wood had been used as a source of energy for a long time. We can ensure a steady supply of firewood if we plant enough trees. You should also be aware of the use of cow-dung cakes as a fuel source. Given India's large livestock population, this can also provide us with a reliable source of fuel. Bio-mass is the source of these fuels because they are made up of plant and animal products.

 

On the other hand, these fuels do not produce much heat when burned and produce a lot of smoke. As a result, technological advancements to increase the efficiency of these fuels are required. When wood is burned in a low-oxygen environment, the water and volatile materials are removed, leaving charcoal as a residue. Charcoal that does not burn with flames produces less smoke and has a higher heat generation efficiency.

 

Similarly, in the absence of oxygen, cow dung, various plant materials such as crop residue, vegetable waste, and sewage decompose to produce bio-gas. It's known as 'gobar-gas' because the starting material is mostly cow dung. Bio-gas is produced in a plant as shown below.

 

 

The plant is built in the shape of a dome and is made of bricks. In the mixing tank, a slurry of cow dung and water is created, which is then fed into the digester.

The digester is a vacuum-sealed chamber with no oxygen. The cow-dung slurry is decomposed or broken down by anaerobic microorganisms that do not require oxygen. The decomposition process takes a few days to complete and produces gases such as methane, carbon dioxide, hydrogen, and hydrogen sulphide. The bio-gas is stored in a gas tank above the digester, from which it is drawn for use through pipes.

 

Bio-gas is a great fuel because it contains up to $75%$ methane. It does not produce smoke and does not produce ash as wood, charcoal, or coal do. It has a large heating capacity. Lighting is also powered by bio-gas. The slurry that remains is removed on a regular basis and used as a high-nitrogen, high-phosphorous manure. The large-scale use of bio-waste and sewage material not only provides energy and manure but also provides a safe and efficient method of waste disposal. Do you believe biomass is a renewable energy source?