What is Geothermal Energy: It is an energy which is obtained from Earth. It is a pollution free source of energy and can be used continually. In the core of Earth, many radioactive materials like magma, uranium and thorium are found in abundance. As per the scientists, these can be sources of energy. Large scale energy can be obtained from these. The electricity produced by geothermal energy is being used in 20 countries. Iceland is having 17 % share of its total energy by geothermal energy. According to one estimate, Iceland will obtain minimum 1700 MW energy annually for the next 100 years from geothermal energy. The Geothermal energy is produced on account of pressure on inner layers, radioactive fission, volcanoes and absorption of solar energy. By the use of geothermal gradient, continuous thermal energy can be obtained. Geothermal energy is being used since Paleolithic times and in Roman times to heat water. Today, it is a better source of producing electricity.
Process of Electricity Generation: In first sight, the process of energy generation appears quite easy. For this a hole is drilled deep inside. Water is taken to hot area and steam is generated. The steam is used to run turbines to produce electricity. This process goes on. The steam is again condensed and put to use. If we have such a pipe that can go to magma, we will get unlimited source of energy. To get energy from inner layers, we have to install thermal reservoirs. For commercial use, we need reservoir which can work above 150 °C. Geyser area of north California, Imperial Valley and Idaho of South California, Montana and Yellostone area of Vyoming have large scale utilization of geothermal energy.
But, present techniques cannot reach magma. scientists has reached till hot belt. According to scientists, below 80 -100 km, molten rocks are at 650 to 1200 °C. These hot materials come to earth's surface by tectonic plates.
Possibilities: Total stored energy in Earth is 1031 joules??. This is coming at the rate of 44.2 TW on Earth's surface.