.png)
Chapter 14v- Sources of Energy
Characteristics ofa good fuel:
High calorific value
Less smoke
Less residue after burning
Easy availability
Inexpensive
Easy to store and transport
Fossil fuels:
Fossil fuels Were formed millionsof years ago, when plants and animal remains got buried under the earth and were subjected to high temperature and pressure conditions.
E.g.: Coal, Petroleum, etc.
These fossil fuels are non-renewable sources of energy and cause environmental problems due to pollution.
Thermal power plants:
Use coal, petroleum and natural gasto produce thermal electricity.
Electricity transmission is very efficient.
The steam produced by burning the fossil fuels runs the turbine to produce electricity
Hydro power plant:
It is the most conventional renewable energy source. Here electricity is generated by the water falling from agreat height. It is clean & nonpolluting source of energy. Dams are constructed to collect water flowing in high altitude rivers.
The stored water has a lot of potential energy. When water is allowed to fall from a height, potential energy converts into to kinetic energy, which rotates the turbines to produce electricity.
Disadvantages of Hydro powerplant: Highly expensive to construct. Dams cannot be constructed on all river sites. Large areas of human habitation and agricultural fields get submerged. People face social and environmental problems. Non-conventional sources:
(1) BioMass:
It is the source of the conventionally used fuels that are usedin India.
E.g: Cowdung cakes, fire-wood, coal, charcoal
Bio gas: It is a mixture of gases produced during decomposition of bio mass in the absence of Oxygen(Anaerobic Respiration).
Methane is the major component of bio gas.
Bio gas plants: Animal dung, sewage, crop residues, vegetable wastes, poultry droppings, etc. are used to produce Bio gas in Bio gasplants.
(2) WindEnergy:
Wind mill converts mechanical energy into electrical energy. Kinetic energy of the wind rotates the wind mills, which are used to lift water, grind grains, etc.
Advantages: Eco friendly Renewable
Disadvantages:
Wind speed not uniform always. Needs a large areato erect series of wind mills. Big amount of investment is needed. Output isless as compared to investment
(3) SolarEnergy:
Solar radiations can be converted to electricity through solar cells (photovoltaic cells).
Photo voltaic cells convert solar radiations directly into electricity through silicon solar cells.
Solar cells are arranged on a large flat sheets to form a solar panel.
Solar cookers are painted black from outside and a large glass plate to trap solar radiations by green houseeffect.
Advantage ofSolar cookers: Eco friendly
Renewable
Used in ruralareas.
Retains allthe nutrients in food dueto slow cooking.
Disadvantages of solar cooker:
Silicon cells are expensive. Solar radiations are not uniform over earth’s surface.
Cannot be used at night or on cloudy days.
Cannot be used to make roti (chapattis) for frying as these require a temperature of 140°C or more.
(Maximum temperature of 100°C only can be achieved in a solarcooker)
Other solar devices- Solar water heater, Solarfurnace
Geo Thermal Energy:
Energy harnessed from the heat of the sun is called Geo thermal energy. Magma is formed when this heat melts the rocks.
The molten rocks and hot gasesare called magma The magma gets collected at some depths below the earth’s surfaces. These places are called “Hot spots” When underground water comes in contact these hot spots, it changes intosteam, which can be used to generate electricity. Advantages of Geo thermal energy: Renewable Inexpensive
Disadvantages of Geo thermal energy:
Only few sites available for harnessing energy.
Expensive
(5) Nuclear Energy:
Energy released when some changes take place in the nucleus of the atom of a substance, is called Nuclear energy. It is usedfor heat generation, fuel for marine vessels.
Advantages or Nuclear Energy:
Alternative source of energy due to depletion of fossil fuels. From a small amount of fuel, a large amount of energy is released.
Disadvantages of Nuclear Energy: Risk of nuclear waste leakage High cost of setting up of nuclear plant Pollution of environment.
(6) Energy from the sea- Tidal Energy: Locations in India – Gulf of Kutch, Gujrat &W. Bengal Depends upon harnessing therise and fall of sea leveldue to tidalaction. Dams are constructed across anarrow part ofsea and turbine converts tidal energy into electrical energy.
Disadvantages:
Uniform tidal action is not seen Wave Energy: Kinetic energy of thewaves of seaare used to rotate turbines.
These turbines generate electrical energy
Comments