Background
Geothermal energy for electricity generation has been commercially produced since 1913(Fridlefsson,2001) It was 1904 In Larderello, Italy that Prince P.G. conti set up the first device to produce electricity from a geothermal steam well. By 1913 at the same location , a 250 KW turbo-alternator became the first power system connected to the grid(DiPippo,2008). During the last three decades the demands have increased and geothermal energy is now being used in over 80 countries worldwide (Fridleifsson,2001). Not only is geothermal energy good for our energy-sufficiency but it has positive impacts on employment (Kammen,Kapadia,Fripp,2004).
How does geothermal energy work?
Through the year almost 50% of the sun’s energy is absorbed into the earth where it maintains a constant temperature (Geosmart Energy, 2012).
Geothermal energy derives in the interior of the earth. Decaying of radioactive material causes heat to be produced and convection and conduction move the heat round the earth. To use the geothermal energy hydrothermal systems have to be used to produce electricity or heat (Kranz,2007).
There are three main technologies in use today to produce electricity from geothermal reservoirs. Dry steam, flash and binary plants. Dry steam plants use high temperatures, vapour-dominant, hydrothermal reservoirs. The steam produced from the well passes directly through the turbine generator unit producing electricity. In single flash power plants the mixture from the well-head is separated into different phases in a flash vessel and vapour is sent to the turbine-generator unit. The binary cycle is appropriate when the water temperature is lower than 150 C (Chamorro, et.al.2012).
Geothermal energy uses this constant renewable energy source by installing loops installed outside underground with a heat pump system. There are a number of loops including horizontal loops, vertical loops, pond or lake loops or open loops. Horizontal loops being the most common type of loop system and mostly used in rural areas, vertical loops which are mainly used in urban areas, pond/lake loops used in houses closest to water bodies and open loops where there is a high capacity of space(geosmart energy,2012)
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Case study : Geothermal use in Iceland
The use of geothermal energy in Iceland has great potential due to the location of Iceland on the Mid-Atlantic Ridge and hence Iceland is well on the way to becoming completely independent from fossil fuels (Kranz,2007).Geothermal energy power facilities currently generate 25% of country’s total electricity, not only is the country now sustaining themselves but the economic growth has been substantial. In the 20th century Iceland was one of the poorest countries dependent on coal and peat, they now all have a very high standard of living (Orkustofnun National Energy Authority,2013).
References
-Chamorro,C.,Mondejar, M.,Ramos,R.,Segovia,J.,Martin,M.,Villamanan,M.,2012. World geothermal power production status: Energy, environmental and economic study of high enthalpy technologies. Energy vol 42.p10-18
-DiPippo R,2008. Geothermal power plants. 2nd ed. Oxford
-Fridleifsson,I.,2001. Geothermal energy for the benefit of the people. Renewable and sustainable Energy reviews vol 5 p299-312.
-Geosmart Energy, 2012. How geothermal energy works. (online) Available at: http://geosmartenergy.com/geothermal-energy/how-it-works.html accessed on : 20th Octover 2013.
-Kammen,D., Kapadia,K.,Fripp,M.,2004. Putting renewables to work: How many jobs can the clean energy industry generate? (pdf) http://community-wealth.org/sites/clone.community-wealth.org/files/downloads/paper-kammen-et-al.pdf
-Kranz,K.,2007.Geothermal energy in Iceland.(pdf). Available at: http://www.geo.tu-freiberg.de/oberseminar/os06_07/Kathrin%20Kranz.pdf
-Orkustofnun National Energy Authrority. 2013. Geothermal.(online) Available at: http://www.nea.is/geothermal/. Accessed on 20th October 2013.
