Conventional Sources of Energy

Key Concepts

• Wind energy
• Biomass .
• Biogas

Introduction: 

Sources of energy are classified as conventional and non conventional source of energy. In this session we are going to learn about few conventional sources and how electricity is harnessed through these energies. 

Explanation: 

Conventional and Non-conventional Sources of Energy : 

Sources of energy are also classified as :  

1. Conventional sources of energy  

2. Nonconventional sources of energy. 

Conventional sources of energy :  

They are those which are used extensively and a meet a marked portion of our energy requirement and these are : 

1. Fossil fuels (coal, oil and natural gas) and

2. Hydro energy (energy of water flowing in rivers). 

3. Biomass energy  

4. wind energy 

Non-conventional sources of energy :  

They are those which are not used as extensively as the conventional ones and meet our energy requirement only on a limited scale.  

Example:  

1. Solar energy,

2. ocean energy (tidal energy, wave energy, ocean thermal energy, OTE),  

3. Geothermal energy 

4. nuclear energy  

These sources of energy which have been tapped with the aid of advances in technology to meet our growing energy needs are also called alternative sources of energy. 

Wind Energy: When large masses of air move from one place to another it is referred to as wind. During this process kinetic energy gets associated with it which is referred to as wind energy. 

Principle of utilisation of wind energy: 

Wind energy is efficiently converted into electrical energy with the aid of a windmill. A 

windmill is a large fan having big blades, which rotate by the force exerted by moving wind on 

them. These blades remain continuously rotating as long as wind is blowing and can be used 

to drive a large number of machines like water pumps, flour mills etc. But these days a 

windmill is used to generate electric current which is used for various purposes and therefore 

wind power stations are established all over the world which convert wind energy directly into 

electrical energy. 

Uses of wind energy: – 

The important uses of wind energy are; 

1. It is used to drive windmills, water lifting pumps and flour mills etc. 

2. It is used to propel sale boats. 

3. It is used to fly engine less aeroplanes or gliders in the air. 

4. It is used to generate electricity used for various purposes like lightening, heating etc. 

Advantages of generating wind energy: – 

The chief advantages of using wind energy are; 

1. It is readily and abundantly available at every place of the earth free of cost. 

2. It is eco-friendly and does not produce any kind of environmental pollution. 

3. It is a renewable source as air itself is a renewable and inexhaustible resource. 

4. It is a cheap source of energy, as it does not involve any costly investment. 

Bio-Mass:- Biomass is defined as living matter or its residue and is a renewable sources of 

energy. 

The biomass includes  

1. all the new plant growth  

2. agricultural and forest residues (like biogases, bark, sae dust, wood shavings, roots, animal droppings etc.)  

3. Carbonaceous wastes (like sewage, garbage, night-soil, etc.)  

4. Biodegradable organic affluent from industries.

Biogas:- Biogas is a mixture of gases produced by anaerobic degradation of biomass in the presence of water but in the absence of oxygen. 

It is a renewable source of energy on account of its production from vastly and continuously available organic wastes. 

Advantages of Biogas:- 

1. A biogas plant, being quite simple, can easily be built in rural areas. A small plant using dung from 3 to 4 heads of cattle is capable of supplying biogas for 6 hours daily for cooking purposes. 

2. Biogas is a clean fuel that burns without smoke and leaves no ash. 

3. The main constituent of biogas, i.e., ethane has a higher calorific value (55kj/g) that of petrol (50kj/g). 

4. The spent slurry, being rich in nitrogen and phosphorus, is good manure. 

5. By using biogas, firewood is saved and deforestation is reduced. 

Composition of Biogas:- Biogas is mainly composed methane (up to 75%), CO2 (25%) and 

traces of other gases such as nitrogen and hydrogen. Whereas methane is a high value 

calorific fuel, carbon dioxide is an inert gas. 

Biogas is prepared in biogas plants which are of two types:  

1. Fixed Dome Type  

2. Floating Gas Holder Type. 

Fixed Dome Type Biogas Plant:- 

The main parts of fixed of dome type of biogas plants are: 

1. Digester. It is well shaped underground tank made of bricks. Its roof is some-shaped which acts as a storage tank for biogas. 

2. Mixing tank. It is constructed on the ground level where cattle dung and water are mixed. 

3. Inlet tank. It is constructed underground below the mixing tank. 

4. Overflow tank. It is constructed slightly below the level of mixing tank. 

5. Outlet tank. It is constructed below the overflow tank. 

Working of Biogas Plant:- 

Cattle dung and water are mixed in equal proportion in the mixing tank to form slurry. This slurry is fed into the digester tank through inlet tank when the digester tank is filled about 2/3rd of its capacity, the dome is left free for collection of biogas. The slurry undergoes anaerobic fermentation and biogas is produced after 50 to 60 days. As biogas is collected in the dome it exerts pressure due to which spent slurry go to the overflow tank through outlet tank and fresh slurry is fed into the digester and continuous supply of biogas is obtained spent slurry is used as manure. 

Questions and answers 

Question 1: Bio gas is an excellent fuel. Justify the statement by giving two reasons. Mention the main constituents of bio gas along with its percentage. 

Answer: 

1. It burns without smoke and leaves no residue therefore causes no atmospheric pollution. 

2. Its heating capacity is high, i.e. it has high calorific value. Main constituents of bio gas: The composition of bio gas varies depending upon the nature of organic matter feeding in’the digester and advanced waste treatment technology. The typical composition of bio gas is 
   Methane                                50 – 75% 
   Carbon dioxide                     25 – 50% 
   Nitrogen                                   0 – 10% 
   Hydrogen                                 0 – 1% 
   Hydrogen sulphide                0 – 3% 

Question 2: Nikhil and Neha went to a remote village in Kerala to meet their grandmother. They were surprised to see a biogas plant in Mr. Nair’s house in the neighbourhood. There were plenty of livestocks and the household used cooking gas from the plant. Also their farms had rich vegetation. They contacted sarpanch of the village and convinced him to set up a biogas plant for village community. 

1. Mention the values displayed by Mr. Nair, Nikhil and Neha. 

2. Explain the possible arguments given by Nikhil and Neha to the sarpanch to convince him to set up community biogas plant. 

Answer. 

1. Mr Nair: Higher degree of general awareness, helping nature. 
   Nikhil and Neha: Knowledge sharing. 

• helping nature. 
• concern for community advantage. 

2. Possible arguments given by Nikhil and Neha in favour to set up community biogas plant, to the sarpanch on 

1. Economical source of energy. 

2. Cleanliness of the whole village. 

3. Use of slurry left behind as mannar which is rich in nitrogen and phosphorous. 

4. It reduces air pollution and greenhouse effect. 

5. It raises the standard of living. 

6. It is beneficial to entire village community. Basically they discuss and explain the advantages of community bio gas plant for the’entire village. 

Summary

• Coal, petroleum and natural gas are fossil fuels. They are exhaustible.
• Wind turbine harness the wind energy to electrical energy.
• Biomass power plant converts chemical energy to heat energy and electrical energy.
• A few advantages of wind energy is:
  • It is readily and abundantly available
  • It is eco-friendly
  • It is a renewable source.
  • It is a cheap source of energy.

• A few advantages of biomass energy is:
  • can easily be built in rural areas.
  • Biogas is a clean fuel
  • has a higher calorific value
  • The spent slurry is good manure.