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Geothermal Energy |
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by Razaan Abakar | 12-02-2018 10:22
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INTRODUCTION Geothermal Energy, energy contained in intense heat that continually flows outward from deep within Earth. This heat originates primarily in the core. Some heat is generated in the crust, the planet's outer layer, by the decay of radioactive elements that are in all rocks. The crust, which is about 5 to 75 km (about 3 to 47 mi) thick, insulates the surface from the hot interior, which at the core may reach temperatures from 4000? to 7000? C (7200? to 12,600? F). Where the heat is concentrated near the surface, it can be used as a source of energy. GEOTHERMAL RESERVOIRS In certain areas, water seeping down through cracks and fissures in the crust comes in contact with this hot rock and is heated to high temperatures. Some of this heated water circulates back to the surface and appears as hot springs and geysers. However, the rising hot water may remain underground in areas of permeable hot rock, forming geothermal reservoirs. Geothermal reservoirs, which may reach temperatures of more than 350? C (700? F), can provide a powerful source of energy. DIRECT USE OF GEOTHERMAL WATER In addition to generating electricity, geothermal water is used directly in spas (balneology), to heat greenhouses (agriculture), and to speed the growth of fish and prawns (see aquaculture). The heat from geothermal water is used for industrial processes and for space heating in homes and other buildings. People in over 35 countries have developed geothermal water for such purposes. A. Industry Industrial uses of the heat from geothermal water include manufacturing paper, pasteurizing milk, and drying timber and other agricultural products. Geothermal waters are used in mining to speed the extraction of gold and silver from ore, and are also piped under sidewalks and roads to keep them from icing over in freezing weather. B. Space Heating One of the most common uses of geothermal water is for heating individual buildings or groups of buildings (district heating). A typical geothermal heating system supplies heat to buildings by pumping water (usually 60? C/140? F or hotter) from a geothermal reservoir. Heat from the geothermal water is transferred through a heat exchanger to city water contained in an adjacent separate piping system. This heated city water is then pumped into the buildings, while the geothermal water is injected back into the reservoir to be reheated so it can be used again. The world's largest geothermal system for district heating is in Reykjavík, Iceland. Almost all the buildings in that city use geothermal heat. GEOTHERMAL ENERGY AND THE ENVIRONMENT Geothermal energy is a renewable resource: Earth's heat is continuously radiated from within, and each year rainfall supplies new water to geothermal reservoirs. Production from individual geothermal reservoirs can be sustained for decades and perhaps even centuries. Compared to other types of power plants, geothermal plants have relatively little effect on the environment. Geothermal power plants have been successfully operated in farm fields, in sensitive desert environments, and in forested recreation areas. Hydrogen sulfide gas (H2S), which can be toxic at very high concentrations, is sometimes present in geothermal reservoirs. However, this gas is removed from geothermal water with antipollution "scrubbing" equipment. Geothermal reservoirs contain higher concentrations of minerals and chemicals than do aquifers used for drinking water. Therefore, wells drilled into geothermal reservoirs have several layers of pipes, or casing, cemented into the ground nearly the entire length of a well. The pipes and cement prevent the deep geothermal water from mixing with freshwater aquifers. Geothermal reservoirs contain some carbon dioxide (CO2) which is released when the hot water turns into steam. Some scientists believe that the buildup of carbon dioxide in the atmosphere-partially the result of burning fossil fuels-is contributing to what may be a gradual increase in global temperatures, because carbon dioxide traps heat from the Sun that is reradiated by Earth. The amount of carbon dioxide released from geothermal power plants, however, ranges from zero to 4 percent of the carbon dioxide released by an equivalent power plant fueled by coal or petroleum. SOURCE: Microsoft Encarta 1993-2017 Microsoft Corporation. All rights reserved.
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2 Comments
Thanks for sharing!
Posted 12-02-2018 13:52
Hi, Razaan! Geothermal energy is a form of energy that has been utilized since way back in history. I think this is because geothermal energy shows on the Earth in the form of hot springs and geysers, making it seem mystical and special. Once people gave geothermal energy attention, they thought about how they could utilize it in their lives. They used the warm water for its heat. Even now, in the modern-day society, a large part of our energy usage is contributed to heating. Geothermal energy is still a part in reducing the combustion of fossil fuels. Thanks for your report!
Posted 12-02-2018 11:54