Geothermal energy is the heat from the Earth. It’s clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth’s surface, and down even deeper to the extremely high temperatures of molten rock called magma. Almost everywhere, the shallow ground orÂ upper
Geothermal energy is the heat from the Earth. It’s clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth’s surface, and down even deeper to the extremely high temperatures of molten rock called magma.
Almost everywhere, the shallow ground orÂ upper 3 meters of the Earth’s surface maintains a nearly constant temperatureÂ between 10Â° and 16Â°C. Geothermal heat pumps can tap into this resource to heatÂ and cool buildings. A geothermal heat pump system consists of a heat pump, anÂ air delivery system (ductwork), and a heat exchanger-a system of pipes buriedÂ in the shallow ground near the building. In the winter, the heat pump removesÂ heat from the heat exchanger and pumps it into the indoor air delivery system.Â In the summer, the process is reversed, and the heat pump moves heat from theÂ indoor air into the heat exchanger. The heat removed from the indoor air during
the summer can also be used to provide a free source of hot water.
Geothermal energy in this countryÂ is used in practice in health centers and spas with thermal springs, and some
countries like Island, use it for district heating of entire cities. In ourÂ country there is a big number of thermal springs that are not used in aÂ rational way, and preliminary studies have shown that a reserve of hot water at
lower depths are in the wider area of northern Bosnia.
GeothermalÂ resources and potential of Bosnia and Herzegovina for space heating was estimatedÂ at about 33 MWth. The temperature at locations in the city of Bosanski SamacÂ (85oC), Kakanj (54oC) and Sarajevo (58oC) is too low to start production ofÂ electricity and therefore the main reason why the reserves are taken intoÂ consideration when it comes to exploiting heat.
Many technologies have been developed to takeÂ advantage of geothermal energy – the heat from the earth.
GeothermalÂ Electricity Production
Most power plants need steam to generateÂ electricity. The steam rotates a turbine that activates a generator, which
produces electricity. Many power plants still use fossil fuels to boil waterÂ for steam. Geothermal power plants, however, use steam produced from reservoirsÂ of hot water found a couple of miles or more below the Earth’s surface. ThereÂ are three types of geothermal power plants: dry steam, flash steam, and binary cycle.
Dry steam power plants draw from undergroundÂ resources of steam. The steam is piped directly from underground wells to theÂ power plant, where it is directed into a turbine/generator unit.
Flash steam power plants are the most common.Â They use geothermal reservoirs of water with temperatures greater than 182Â°C.Â This very hot water flows up through wells in the ground under its ownÂ pressure. As it flows upward, the pressure decreases and some of the hot waterÂ boils into steam. The steam is then separated from the water and used to powerÂ a turbine/generator. Any leftover water and condensed steam are injected backÂ into the reservoir, making this a sustainable resource.
Binary cycle power plants operate on water atÂ lower temperatures of about 107Â°-182Â°C. These plants use the heat from the hotÂ water to boil a working fluid,Â usually an organic compound with a low boiling point. The working fluid isÂ vaporized in a heat exchangerÂ and used to turn a turbine. The water is then injected back into the ground to
be reheated. The water and the working fluid are kept separated during theÂ whole process, so there are little or no air emissions.
Small-scale geothermal power plants (under 5Â megawatts) have the potential for widespread application in rural areas,Â possibly even as distributed energy resources. Distributed energy resourcesÂ refer to a variety of small, modular power-generating technologies that can beÂ combined to improve the operation of the electricity delivery system.
GeothermalÂ Direct Use
When a person takes a hot bath, the heat fromÂ the water will usually warm up the entire bathroom. Geothermal reservoirs ofÂ hot water, which are found a couple of miles or more beneath the Earth’sÂ surface, can also be used to provide heat directly. This is called the directÂ use of geothermal energy.
Geothermal direct use dates back thousands ofÂ years, when people began using hot springs for bathing, cooking food, andÂ loosening feathers and skin from game. Today, hot springs are still used asÂ spas. But there are now more sophisticated ways of using this geothermalÂ resource.
In modern direct-use systems, a well isÂ drilled into a geothermal reservoir to provide a steady stream of hot water.
The water is brought up through the well, and a mechanical system – piping, aÂ heat exchanger, and controls – delivers the heat directly for its intended use.Â A disposal system then either injects the cooled water underground or disposes
of it on the surface.
Geothermal hot water can be used for manyÂ applications that require heat. Its current uses include heating buildings
(either individually or whole towns), raising plants in greenhouses, dryingÂ crops, heating water at fish farms, and several industrial processes, such asÂ pasteurizing milk. With some applications, researchers are exploring ways to
effectively use the geothermal fluid for generating electricity as well.