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Geothermal energy
From Wikipedia, the free encyclopedia
Steam rising from the Nesjavellir Geothermal Power Station in Iceland.
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Geothermal energy is thermal energy generated and stored in the Earth. Thermal energy is energy that determines the temperature of matter. Earth’s geothermal energy originates from the original formation of the planet, from radioactive decay of minerals and from volcanic activity. The geothermal gradient, which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the surface.
From hot springs, geothermal energy has been used for bathing since Paleolithic times and for space heating since ancient Roman times, but it is now better known for electricity generation. Worldwide, about 10,715 megawatts (MW) of geothermal power is online in 24 countries. An additional 28 gigawatts of direct geothermal heating capacity is installed for district heating, space heating, spas, industrial processes, desalination and agricultural applications.[1]
The Research paper on Heat Flow Geothermal Energy Water
... total installed capacity of 10, 000 MW thermal (see Boyle, G 10 p 359). Geothermal energy was first used for power generation in ... partnership with Utili com, a French-owned energy management company to form the Southampton Geothermal Heating Company (see Smith, M 4 p ... to the development of the first geothermal energy and combined heat and power (CHP) district heating and chilling scheme in the UK. ...
Geothermal power is cost effective, reliable, sustainable, and environmentally friendly,[2] but has historically been limited to areas near tectonic plate boundaries. Recent technological advances have dramatically expanded the range and size of viable resources, especially for applications such as home heating, opening a potential for widespread exploitation. Geothermal wells release greenhouse gases trapped deep within the earth, but these emissions are much lower per energy unit than those of fossil fuels. As a result, geothermal power has the potential to help mitigate global warming if widely deployed in place of fossil fuels.
The Earth’s geothermal resources are theoretically more than adequate to supply humanity’s energy needs, but only a very small fraction may be profitably exploited. Drilling and exploration for deep resources is very expensive.[citation needed]Forecasts for the future of geothermal power depend on assumptions about technology, energy prices, subsidies, and interest rates.
The adjective geothermal originates from the Greek roots geo, meaning earth, and thermos, meaning heat.
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Environmental effects
Geothermal power station in the Philippines
Krafla Geothermal Station in northeast Iceland
Fluids drawn from the deep earth carry a mixture of gases, notably carbon dioxide (CO2), hydrogen sulfide (H2S),methane (CH4) and ammonia (NH3).
These pollutants contribute to global warming, acid rain, and noxious smells if released. Existing geothermal electric plants emit an average of 122 kilograms (269 lb) of CO2 per megawatt-hour (MW·h) of electricity, a small fraction of the emission intensity of conventional fossil fuel plants.[13] Plants that experience high levels of acids and volatile chemicals are usually equipped with emission-control systems to reduce the exhaust.
In addition to dissolved gases, hot water from geothermal sources may hold in solution trace amounts of toxic chemicals such as mercury, arsenic, boron, and antimony.[14] These chemicals precipitate as the water cools, and can cause environmental damage if released. The modern practice of injecting cooled geothermal fluids back into the Earth to stimulate production has the side benefit of reducing this environmental risk.
The Essay on Geothermal Energy 2 Heat Water Hot
... is more efficient in home heating and cooling than the geothermal heat pump. The pump operates on ... quarters of sulfur-dioxide emissions (acid rain), a third of nitrogen-oxide emissions (inducing formation of ... it is relatively expensive to start a geothermal plant, which would include testing land, building, tunneling, ... release of greenhouse gases caused by fossil fuel use. Sources of this type of energy ...
Direct geothermal heating systems contain pumps and compressors, which may consume energy from a polluting source. This parasitic load is normally a fraction of the heat output, so it is always less polluting than electric heating. However, if the electricity is produced by burning fossil fuels, then the net emissions of geothermal heating may be comparable to directly burning the fuel for heat. For example, a geothermal heat pump powered by electricity from a combined cycle natural gas plant would produce about as much pollution as a natural gas condensing furnace of the same size.[11] Therefore the environmental value of direct geothermal heating applications is highly dependent on the emissions intensity of the neighboring electric grid.
Plant construction can adversely affect land stability. Subsidence has occurred in the Wairakei field in New Zealand[15] and in Staufen im Breisgau, Germany.[16] Enhanced geothermal systems can trigger earthquakes as part of hydraulic fracturing. The project in Basel, Switzerland was suspended because more than 10,000 seismic events measuring up to 3.4 on the Richter Scale occurred over the first 6 days of water injection.[17]
Geothermal has minimal land and freshwater requirements. Geothermal plants use 3.5 square kilometres (1.4 sq mi) per gigawatt of electrical production (not capacity) versus 32 square kilometres (12 sq mi) and 12 square kilometres (4.6 sq mi) for coal facilities and wind farms respectively.[15] They use 20 litres (5.3 US gal) of freshwater per MW·h versus over 1,000 litres (260 US gal) per MW·h for nuclear, coal, or oil.[15]
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Direct application
Main articles: Geothermal heating and geothermal heat pump
In the geothermal industry, low temperature means temperatures of 300 °F (149 °C) or less. Low-temperature geothermal resources are typically used in direct-use applications, such as district heating, greenhouses, fisheries, mineral recovery, and industrial process heating. However, some low-temperature resources can generate electricity using binary cycle electricity generating technology.[9]
The Term Paper on Heat Pump
... but no heat pump, since for this technology the ground temperature is ... direct geothermal heating, though the latter will contribute in some small measure to all heat in the ground. Geothermal heat, when used for heating, requires a circulation pump ...
Approximately 70 countries made direct use of 270 petajoules (PJ) of geothermal heating in 2004. More than half went for space heating, and another third for heated pools. The remainder supported industrial and agricultural applications. Global installed capacity was 28 GW, but capacity factors tend to be low (30% on average) since heat is mostly needed in winter. The above figures are dominated by 88 PJ of space heating extracted by an estimated 1.3 million geothermal heat pumps with a total capacity of 15 GW.[1] Heat pumps for home heating are the fastest-growing means of exploiting geothermal energy, with a global annual growth rate of 30% in energy production.[10]
Direct heating is far more efficient than electricity generation and places less demanding temperature requirements on the heat resource. Heat may come fromco-generation via a geothermal electrical plant or from smaller wells or heat exchangers buried in shallow ground. As a result, geothermal heating is economic at many more sites than geothermal electricity generation. Where natural hot springs are available, the heated water can be piped directly into radiators. If the ground is hot but dry, earth tubes or downhole heat exchangers can collect the heat. But even in areas where the ground is colder than room temperature, heat can still be extracted with a geothermal heat pump more cost-effectively and cleanly than by conventional furnaces.[11] These devices draw on much shallower and colder resources than traditional geothermal techniques, and they frequently combine a variety of functions, including air conditioning, seasonal energy storage, solar energy collection, and electric heating. Geothermal heat pumps can be used for space heating essentially anywhere.
Geothermal heat supports many applications. District heating applications use networks of piped hot water to heat many buildings across entire communities. InReykjavík, Iceland, spent water from the district heating system is piped below pavement and sidewalks to melt snow.[12] Geothermal desalination has been demonstrated.
The Term Paper on Renewable Energy Micro-Generation Prospects and Suitability in Helmand Province in Afghanistan
SUITABILITY OF RENEWABLE MICRO-GENERATION TECHNOLOGY IN HELMAND PROVINCE AND POSSIBLE ISSUES THAT MAY ARISE FROM THEIR INTRODUCTION Introduction There is a requirement to write a technical essay on the suitability of various micro-generation schemes for use within Helmand province in Afghanistan and the possible issues that may arise from their introduction. Scope This essay highlights the ...
