Fuels made from plant and animal products is known as Bio mass.
Example - Wood, Cow Dung
These fuels do not produce much heat during burning and gives out a lot of smoke when they are burnt.
So, just burning wood and cow dung are not enough for our energy requirements.
Thus, technological advancements are made to improve the efficiency of these fuels
Improving Efficiency of burning Wood
When wood is burned in limited supply of Oxygen,
water and other volatile materials inside it get removed
and Charcoal is left behind as residue.
Charcoal is a better fuel than wood because
- It has higher heat generation efficiency
- Charcoal burns without flames and gives out less smoke
Similarly, to improve the efficiency of cow-dung,
we convert it into Bio Gas
Earlier, Cow Dung was burned directly to produce produce heat for cooking. But it was inefficient
So, to improve its efficiency, we converted Cow-Dung into Bio Gas
Cow-dung, vegetable waste, sewage and other residue after harvesting crops are decomposed in absense of Oxygen to give bio-gas.
Since the starting material is mainly cow-dung, it is also known as Gobar Gas.
Let's look at how a Bio-gas is produced in a Bio Gas Plant
Bio Gas Plant
In a Bio-Gas plant
- The plant is made of a dome like structure with bricks
- A slurry of cow-dung and water is made in the mixing tank from where it is fed to the digester
- Digester is a sealed chamber where there is no oxygen
- Anaeorobic organisms in the digester break down down complex compounds of the cow-dung slurry
- After 2-3 days of decomposition, gases like Methane, Carbon Dioxide, Hydrogen and Hydrogen Sulphide are generated
- This Bio-gas is stored in the gas-tank above the digester, and it is drawn through pipes for their use
- The slurry left behind is used as Manure, rich in Nitrogen and Phosphorous
Some important points about Bio Gas
- It contains 75% Methane, so it is an excellent fuel
- It burns without smoke and leaves no residue (like ash in wood, charcoal from coal burning)
- It is also used for lighting
- The slurry left behind is removed periodically and used as Manure - rich in Nitrogen and Phosphorous
- Large scale utilisation of bio-mass provides a safe and efficient method of waste disposal
Is Bio-Mass Renewable or Non-Renewable?
Bio-Mass is a Renewable source of Energy as we can always grow more crops and trees and waste material needed to create Bio-Mass will always be there
Advantages of Bio-Mass
- The materials used to produce Bio-Mass are infinite, thus it is a renewable source of energy
- It is less expensive than fossil fuels
- It produces an excellent fuel which can burn without smoke
- It reduces the amount of garbage dumped in landfills and
Disadvantages of Bio-Mass
- It is not as energy efficient as burning Fossil fuels
- It is not entirely clean. Whie BioMass doesn’t produce Carbon Dioxide on burning, it produces Methane, which is harmful to Earth’s Ozone Layer
Note : - Fuel and Energy are different things.
Fuel means anything which we burn to produce heat energy