Geo-thermal and tidal energy

Geo – thermal (geo-thermal means earth –heat): The earth has three layers i.e. the core, the mental and the crust. The core is the central part of the earth which is surrounded by the mantle. The mantle is surrounded by the uppermost layer of the earth called the crust. The mantle of the earth has molten mass called magma. This magma consists of molten rocks, gases and steam at very high temperature. Due to some geological changes, the hot magma rises up and is collected in the crust of the earth. The region in the crust where the hot magma is collected are called hot spots. The heat energy stored in the hot sports of the earth’s crust is called geo-thermal energy. This energy heats the underground water. The hot underground water comes automatically out of the earth’s surface in certain region where crust is weak in the form of fountains known as water hot water springs or geysers. Geo thermal energy can be converted continuously into electricity for 24 hours throughout the year. Geo thermal energy causes no pollution, so it is environment friendly. The cost of converting geo thermal energy into electricity is very less.

Tidal energy: the rise and fall of ocean water due to the attraction of the moon is called tide. The rise in water is called high tide and the fall in water is called low tide. The rise and fall in water occurs twice a day in a oceans. At the time new and full moon, when the sun and the moon are in a straight line, tides are very high. When the sun and the moon are at right angle from the earth, tides are low. The kinetic energy of water during tides is used to produce electricity. Tidal power plants are constructed near narrow bays. During tides, the gates of the dam are opened. The rising water is allowed to fall on the turbine of the generator which produces electricity. Thus, kinetic energy of the water is converted into electrical energy. During low tides, gates of the dam are closed and hence the water level behind the dam rises. This raised water has potential energy. Again the gates are opened and the water is allowed to fall back into the bay. This falling water is used to rotate the turbine of the generator. Hence, the electricity is produced continuously.