Sources of Energy

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Sources of energy which are known to most of the people. E.g., fossil fuels, biomass etc.

1. Conventional Sources of Energy
2. Fossil fuels (Coal, Petroleum)
3. Thermal power plant
4. Hydropower plants
5. Geothermal energy

Non-conventional Sources of Energy

1. Solar energy (e.g., solar cooker, solar cell panel)
2. Energy from the sea (tidal wave, OT energy)
3. Biomass-biogas plant
4. Nuclear energy
5. Wind energy

Fossil fuels are the remains of prehistoric plants and animals which got buried deep inside the early millions of years ago due to some natural processes.

The energy of fossil fuels is in fact, that solar energy which was trapped by natural processes a very long time ago. Coal, petroleum and natural gas are fossil fuels.

Formation of Fossil Fuels: During its formation, an entire organism or its parts often get buried in sand or mud. These, then decay and disintegrate leaving no signs of their existence. In fact, the harder parts of organisms after their death, settle down and are covered by sediments and subjected to extreme pressure and temperature of the earth converts them into fossil fuels, the process is referred to as fossilization.

Disadvantages of Fossil Fuels:

1. The fossil fuels are non-renewable sources of energy and once used cannot be renewed.
2. The burning of fossil fuels causes air pollution.
3. The fossil fuels reserves in the earth are limited and may get exhausted soon.

Hydropower plants convert the potential energy of falling water into electricity.

In order to produce hydel electricity, high-rise dams are constructed on the river to obstruct the flow of water and thereby collect water in larger reservoirs.

The water level rises and in this process, the kinetic energy of flowing water gets transformed into potential energy.

Advantages of generating hydroelectricity:

1. It is readily and abundantly available everywhere free of cost.
2. It is eco-friendly and does not produce any kind of environmental pollution.
3. It is a renewable source as water itself is a renewable and inexhaustible resource.
4. It is a cheap source of energy, as it does not involve any costly investment.

Disadvantages :

1. Large areas of agricultural land, a vast variety of flora and fauna, human settlements get submerged in the water reservoir formed by the dam.
2. Large ecosystems are destroyed.
3. Vegetation that submerged under water rots under anaerobic conditions and produces a large amount of methane which is a greenhouse gas.
4. Creates the problems of satisfactory rehabilitation of displaced people.

The dead parts of plants and trees and the waste materials of animals and man are called Biomass.

The biomass includes

1. All the new plant growth
2. agricultural and forest residues (like biogases, bark, sawdust, wood shavings, roots, animal droppings etc.)
3. Carbonaceous wastes (like sewage, garbage, night-soil, etc.)
4. Biodegradable organic effluent 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.

The 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

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.

The term thermal power plant is used since fuel is burnt to produce heat energy which is converted into electrical energy.

A large amount of fossil fuels are burnt every day in power stations to heat up water to produce steam which further runs the turbine to generate electricity. The transmission of electricity is more efficient than transporting coal or petroleum over the same distance. Therefore, many thermal power plants are set up near coal or oil fields.