Why is there a need for harnessing non conventional sources of energy? How can energy be harnessed from the sea in different ways?
Answers
The two main reasons to harness non-conventional sources of energy are: (i) The population of the world is increasing at a very rapid rate due to which demands for energy is increasing day by day. As, fossil fuels like coal, petroleum, are present in a limited amount which and are likely to finish one day so the need for alternative sources of energy is essential. (ii) Use of conventional sources of energy (coal, petroleum etc.) causes pollution. To reduce pollution use of non-conventional sources of energy is essential. Two different ways of harnessing energy from ocean are: Tidal energy: Due to the gravitational pull of mainly the moon on the spinning earth, the level of water in the sea rises and falls. This phenomenon is called high and low tides and the difference in sea-levels gives us tidal energy. Tidal energy is harnessed by constructing a dam across a narrow opening to the sea. A turbine fixed at the opening of the dam converts tidal energy to electricity. Ocean thermal energy: The water at the surface of the sea or ocean is heated by the Sun while the water in deeper sections is relatively cold. This difference in temperature is exploited to obtain energy in ocean-thermal-energy conversion plants. These plants can operate if the temperature difference between the water at the surface and water at depths up to 2 km is 20 K (20°C) or more. The warm surface-water is used to boil a volatile liquid like ammonia. The vapours of the liquid are then used to run the turbine of generator. The cold water from the depth of the ocean is pumped up and condense vapour again to liquid.
Answer:
Following are the main reasons: because of which there is a need to harness non-conventional sources of energy:
(a) Non-renewable fuels: Fossil fuels are the main energy sources for us. But it takes millions of years for the formation of fossil fuel. The rate at which we are using them means they are not going to last many years from now. They would be definitely exhausted sooner rather than later.
(b) Polluting fuels: Burning of fossil fuels releases oxides of carbon, nitrogen and Sulphur. These are polluting gases. Carbon dioxide is a greenhouse gas. Carbon monoxide can be poisonous even in low concentration. Oxides of Sulphur and nitrogen cause acid rain. Air pollution also results in increased cases of respiratory problems.
Following are various ways of harnessing energy from sea:
Wave energy
Tidal energy
Ocean thermal energy