Question

What is biomass? What can be done to obtain bio-energy using biomass?

Answer 1

Biomass is fuel that is developed from organic materials, a renewable and sustainable source of energy used to create electricity or other forms of power. Some examples of materials that make up biomass fuels are: scrap lumber, forest debris, certain crops, manure and some types of waste residues.

Principle:

Biogas is produced as a result of anaerobic fermentation of biomass in the presence of water.
Construction:

The biogas plant is a brick and cement structure having the following five sections:
Mixing tank present above the ground level
Inlet chamber: The mixing tank opens underground into a sloping inlet chamber
Digester: The inlet chamber opens from below into the digester which is a huge tank with a dome like ceiling. The ceiling of the digester has an outlet with a valve for the supply of biogas
Outlet chamber: The digester opens from below into an outlet chamber
Overflow tank: The outlet chamber opens from the top into a small over flow tank
Working:
The various forms of biomass are mixed with an equal quantity of water in the mixing tank. This forms the slurry
The slurry is fed into the digester through the inlet chamber. The temperature of the slurry must be maintained around 35 degrees C. Any drop in temperature will reduce the anaerobic activity and hence the yield of biogas
When the digester is partially filled with the slurry, the introduction of slurry is stopped and the plant is left unused for about two months
During these two months, anaerobic bacteria present in the slurry decompose or ferment the biomass in the presence of water
As a result of anaerobic fermentation, biogas is formed, which starts collecting in the dome of the digester
As more and more biogas starts collecting, the pressure exerted by the biogas forces the spent slurry into the outlet chamber
From the outlet chamber, the spent slurry overflows into the overflow tank
The spent slurry is manually removed from the overflow tank and used as manure for plants
The gas valve connected to a system of pipelines is opened when a supply of biogas is required
To obtain a continuous supply of biogas, a functioning plant can be fed continuously with the prepared slurry
Advantages of Fixed Dome Type of Biogas Plant:

• Requires only locally and easily available materials for construction
• Inexpensive
• Easy to construct
• Due to the above reasons, this plant is also called the Janata Gobar gas plant.

Below is the biogas plant with a labelled diagram.