The renewable sources of energy or the alternative forms of energy which can save us from the energy crisis and become the major sources of energy in future are : Solar energy; Waste bio-mass energy; Sea-wave energy, Tidal energy, Geothermal energy, Wind energy and Fusion energy. And of course, the ‘Energy conservation is also very important. We shall now discuss all these sources of energy in detail.
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1. Solar Energy. The sun is almost an inexhaustible source of energy. Sun’s heat energy can be used directly in solar cookers to cook food or in solar heaters to heat water. The sun’s energy can be concentrated by big concave reflectors and used to boil water to get steam and produce electricity. Solar cells can convert the sun’s energy directly into electricity. The biggest advantage of solar energy is that it does not cause any pollution.
2. Waste Bio-Mass Energy. The waste bio-mass like cattle dung, plant residues (crop residues) and sewage, etc., on fermentation in the absence of air produces a combustible gas called bio-gas. This can be developed as a good source of energy in rural areas (village areas).
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3. Sea- Wave Energy. The waves on the surface of sea move very rapidly and possess a lot of kinetic energy. The energy of moving sea-waves can be used to generate electricity. Specially shaped devices have been designed which move as waves in the sea pass them. This movement can be used to drive dynamos to generate electricity.
4. Tidal Energy. The enormous movement of water round the world’s coasts between high and low tides provides a very large source of energy. This energy can be tapped by constructing a tidal barrage. The difference in the depth of water on either side of the barrage is used to drive turbines and produce electricity.
5. Wind Energy. The traditional wind-mill is well known but it is very uncommon these days. Newer types of wind-mills are being developed which could be a good source of energy in exposed, windy places.
6. Nuclear Fusion Energy. All the existing nuclear power stations are based on the nuclear fission principle, the source of energy being the fission of radioactive substances like uranium-235. But the supply of uranium-235 is limited and hence cannot last for a long time to come.
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Another type of nuclear reaction which can become an extremely good source of energy for future is the fusion together of heavy hydrogen nuclei to form helium nucleus, with a tremendous release of energy. This nuclear fusion reaction takes place at an uncontrolled rate in a hydrogen bomb explosion. Scientists are trying to control the nuclear fusion reactions in order to produce a nuclear fusion power station. If they are successful, then we would have a virtually unlimited source of energy because the oceans contain enough of heavy hydrogen (in the form of heavy water) to last for many thousand million years in the nuclear fusion reactors.
7. Geothermal Energy. A few places in the world have the temperature near the surface sufficiently high to produce steam which is then used to drive turbines and generate electricity in the usual manner.
8. Energy Conservation. It is a common saying that “Energy Saved is Energy Produced.” So, we should try to prevent the energy from being wasted uselessly. This can be done everywhere, in homes, in schools, in transport and in industry. In many homes, the lights and fans are kept switched on even when not needed; radio and T.V. are kept on unnecessarily; and water is heated to high temperature by sheer negligence and then allowed to cool for taking bath in winter.
All these are highly undesirable practices which waste the precious electrical energy. So, whenever you see a fan or light on unnecessarily in your home or school, please switch it off at once. We should take a great care in using the fossil fuels like coal, petroleum products (like petrol, kerosene and diesel), and natural gas. These should be conserved as far as possible and used when no alternative source of energy is available.