Geothermal heating has been used since the time of the
Roman Empireas a way of heating buildings and spas by utilizing sources of hot waterand steamthat exist near the Earth's surface. [Climate.Org - Renewable Energy: Geothermal, "http://www.climate.org/topics/green/geo.shtml".] The ultimate source of geothermal energy is believed to be from the radioactive decaythat occurs deep within the Earth’s crustcite book |title=Heat Pumps, Energy Management and Conservation Handbook, 2008|pages=p. 9-3] , or Tidal heating from the Moon"http://en.wikipedia.org/wiki/Tidal_force"] . Some areas, including substantial portions of many western states (U.S.), are underlain by relatively shallow geothermal resources. [ [http://www.geothermal.org/what.html What is Geothermal? ] ] Similar conditions exist in Iceland, parts of Japan, and other geothermal hot spots around the world. These resources can be classified as low temperature (less than 90°C or 194°F), moderate temperature (90°C - 150°C or 194 - 302°F), and high temperature (greater than 150°C or 302°F). Where such geothermalresources are available, it is possible to distribute hot water or steam to multiple buildings. This technique, long practiced throughout the world in locations such as Reykjavik, Iceland[ University of Rochester- History of the utilization of geothermal sources of energy in Iceland, "http://www.energy.rochester.edu/is/reyk/history.htm".] , Boise, Idaho, [ District Heating Systems in Idaho, "http://www.idwr.state.id.us/energy/alternative_fuels/geothermal/detailed_district.htm".] , and Klamath Falls, Oregon[ [http://www.geothermie.de/egec-geothernet/ci_prof/america/usa/klamath_falls_geothermal_distric.htm Klamath Falls Geothermal District Heating Systems ] ] is known as geothermal district heating.
Geothermal heat pumps
In recent years, the term geothermal heating has frequently been used to refer to the heating and
coolingthat can be achieved through the use of a geothermal heat pump. This technique is generally for residential use. It involves a refrigerantliquid being pumped through pipes in the ground, heating the liquid. This liquid then is brought back into the house, and the heat exchanged. The same technique is used to cool the house.
Geothermal heat pumps take advantage of the natural constant temperature of the earth.Goswami, Yogi D., Kreith, Frank, Johnson, Katherine (2008), p. 9-4.] During winter when the ground temperature is warmer than the air above it, geothermal heat pumps use the earth’s soil (or groundwater) to recover the earth’s heat. In contrast, an
air-source heat pumpwill remove heat from the cold outside air and thus requires more energy.
In the summer months, geothermal heat pumps deliver heat to the same relatively cool soil (or groundwater) rather than delivering it to the hot outside air. As a result, the heat is pumped over a smaller temperature difference with a geothermal heat pump and this leads to higher efficiency and lower energy use.Goswami, Yogi D., Kreith, Frank, Johnson, Katherine (2008), p. 9-7.]
Hot dry rock
The conditions necessary for water to circulate to the earth’s surface are present in less than 10 percent of Earth’s land area.
Union of Concerned Scientists- How Geothermal Energy Works, "http://www.ucsusa.org/clean_energy/renewable_energy_basics/offmen-how-geothermal-energy-works.html".] Therefore, geothermal heating is not always a feasible option. Hot dry rockis a method of capturing the heat embedded in these dry areas. First, high-pressure water is pumped down a borehole and through the rocks to break them apart. Water is then pumped from the surface through the ground and the broken hot rocks. This causes the water temperature to rise. The hot water is returned to the surface through a second well and is used to drive turbines for electricity or to provide heat. The water is then returned to the ground and the process repeated.
Fenton Hill facility
There was an experimental facility built in 1974 in Fenton Hill, New Mexico that studied hot dry rock. A well was drilled 11,500 feet into rock at 430 °F to demonstrate the feasibility of hot dry rock technology. The water returned to the surface at 360 °F after being pumped down the well at 80 °F. The plant produced as much as five megawatts of power, proving that energy from hot dry rock can be extracted for practical applications.
Geothermal energy is a type of renewable energy that encourages conservation of natural resources. According to the U.S.
Environmental Protection Agency, geo-exchangesystems save homeowners 30-70 percent in heating costs, and 20-50 percent in cooling costs, compared to conventional systems. [cite web |title=Geothermal Heat Pump Consortium, Inc. |url=http://geoexchange.us/about/how.htm |accessdate=2008-04-27] Geo-exchange systems also save money because they require much less maintenance. In addition to being highly reliable they are built to last for decades and can add considerably the resale value of a structure.
Some utilities, such as
Kansas City Power and Light, offer special, lower winter rates for geothermal customers, offering even more savings.Goswami, Yogi D., Kreith, Frank, Johnson, Katherine (2008), p. 9-8.]
Future of geothermal heating
Geothermal energy is one of the few renewable energy technologies that—like
fossil fuels—can supply continuous, base loadpower. In the past, electricity costs from geothermal facilities were noticeably high. Over the past few decades, these costs have steadily declined. Some geothermal facilities have noticed a 50 percent reduction in the price of electricity over the past 25 years. New facilities can produce electricity for between 4.5 and 7.3 cents per kilowatt-hour, making it competitive with new conventional fossil fuel-fired power plants. The future for the direct use of geothermal resources is becoming more attractive as prices continue to drop. It is predicted that geothermal heating will continue to become a more popular option for homes and businesses seeking long term cost and energy savings.
Geothermal exchange heat pump
Geothermal heat pump
Annualized geothermal solar
* [http://www1.eere.energy.gov/geothermal Energy Efficiency and Renewable Energy - Geothermal Technologies Program]
* [http://geothermal.id.doe.gov/ Idaho National Laboratory - Geothermal Energy]
* [http://geoheat.oit.edu Oregon Institute of Technology - Geo-Heat Center]
* [http://www.smu.edu/geothermal/ Southern Methodist University - Geothermal Lab]
* [http://www.nrel.gov/learning/re_geo_direct_use.html National Renewable Energy Lab]
* [http://reddawn.com/featart11-98.html REDdawn - Geothermal Heating and Cooling Systems]
Wikimedia Foundation. 2010.
Look at other dictionaries:
Geothermal power — (from the Greek roots geo , meaning earth, and therme , meaning heat) is energy generated by heat stored in the earth, or the collection of absorbed heat derived from underground, in the atmosphere and oceans. Prince Piero Ginori Conti tested the … Wikipedia
Geothermal — is related to energy and may refer to: * Geothermal (geology), heat that comes from within the Earth * Direct exchange geothermal heat pump, a method of heating and cooling with the energy of the earth using direct exchange of heat * Geothermal… … Wikipedia
Heating — may refer to: *HVAC: Heating, ventilation and air conditioningHeating devices, or systems: *Block heater, or headbolt heater, an electric heater that heats the engine of a car to ease starting in cold weather *Boiler *Cathode heater, a coil or… … Wikipedia
Geothermal heat pump — A geothermal heat pump system is a heating and/or an air conditioning system that uses the Earth s ability to store heat in the ground and water thermal masses. These systems operate based on the stability of underground temperatures: the ground… … Wikipedia
Geothermal power in the United Kingdom — The potential for exploiting geothermal energy in the United Kingdom on a commercial basis was initially examined by the Department of Energy in the wake of the 1973 oil crisis. Several regions of the country were identified, but interest in… … Wikipedia
Geothermal power in Iceland — Because of the special geological situation in Iceland, the high concentration of volcanoes and geothermal energy are very often used for heating and production of electricity. The energy is so inexpensive that in the wintertime, some pavements… … Wikipedia
Geothermal power in Kenya — Workers at Olkaria Geothermal Power Plant Geothermal power is very cost effective in the Rift area of Kenya, East Africa. Kenya was the first African country to build geothermal energy sources. Kenya Electricity Generating Company (KenGen) has… … Wikipedia
Geothermal power in Turkey — Turkey currently has the 5th highest direct utilization and capacity of geothermal energy in the world. Turkey s capacity as of 2005 is 1495 MWt with a utilization of 24,839.9 TJ/year or 6900.5 GWh/year at a capacity factor of 0.53. Most of this… … Wikipedia
Geothermal Energy — Energy produced by the internal heat of the earth; geothermal heat sources include: hydrothermal convective systems; pressurized water reservoirs; hot dry rocks; manual gradients; and magma. Geothermal energy can be used directly for heating or … Energy terms
geothermal energy — Power obtained by using heat from the Earth s interior. Most geothermal resources are in regions of active volcanism. Hot springs, geysers, pools of boiling mud, and fumaroles are the most easily exploited sources. The ancient Romans used hot… … Universalium