Bio-mass

These notes are based on the chapter Sources of Energy of class 10 NCERT book and CBSE syllabus.

The plants and animals constitute the biomass. In the context of sources of energy, biomass is a matter obtained from living beings (which are dead), and used for energy production.

Plants are the main source of biomass. Biomass can be directly used to produce energy. For example: firewood from plants is used as kitchen fuel. Biomass can also be converted into other forms and then can be used for energy production. For example: wood can be turned into pellets to be used as the source of energy. Now-a-days, biomass is also converted into biofuels.

Burning of biomass for production of energy produces carbon dioxide gas. You have read that carbon dioxide is a greenhouse gas which ends up polluting the air. If large number of trees can be planted, then a continuous supply of firewood can be ensured. Growing large number of trees helps in offsetting the air pollution caused by burning of biomass fuels.

Farm waste, such as stalks of harvested plants and dung of cattle, can be used to generate methane. The decomposition of biomass produces methane, which can be channelized for useful purposes.

Bio-gas Plant

Bio-gas plant can be very useful in solving the energy need of rural areas. In Hindi, biogas plant is called gobar gas plant because gobar (cow dung) is the main source of biomass in such plants.

• A bio-gas plant is a dome-like structure which is usually built from bricks and concrete.
• There is an inlet for slurry, an outlet for biogas and another outlet for digested material.
• In the mixing tank, the slurry is made from cow-dung and water.
• The slurry then goes to the digester, which is a closed chamber.
• Since oxygen is absent in the digester, the anaerobes carry on their work of decomposition.

The process of decomposition produces biogas. Biogas has about 70% of methane and the rest is composed of other gases. The biogas is channelized through a pipe and can be utilized as kitchen fuel and also as fuel for getting light. The slurry, left behind, is removed. It is used as manure, once it dries.

In other words, biogas is produced by methanogens and sulphate-reducing bacteria through anaerobic process. The process by which bacteria breakdown biodegradable material in the absence of oxygen is called anaerobic digestion.

Importance of Biogas Plant

• Can be the replacement of fossil fuels
• In decreasing or eliminating the energy footprint of waste treatment plants
• In decreasing methane emission from landfills
• Displacing industrially produced chemical fertilizers
• Decreasing vehicle movements
• Decreasing electrical grid transportation losses
• Decreasing usage of LP Gas for cooking
• Can prove an important step for the Zero Waste initiatives