Geothermal power is the power generated by geothermal energy. The technologies used include dry steam power plants, flash steam power plants and binary cycle power plants. Geothermal power plants are currently used in 24 countries, while geothermal heating is in use in 70 countries.
By 2015, geothermal power capacity worldwide is 12.8 gigawatts (GW), of which 28 percent or 3,548 megawatts are installed in the United States. The international market grew at an average annual rate of 5 percent for three years until 2015, and global geothermal power capacity is expected to reach 14.5-17.6 GW by 2020. Based on current geological knowledge and technologies expressed by GEA public, the Geothermal Energy Association (GEA) estimates that only 6.9 percent of the total global potential has been tapped so far, while the IPCC reports geothermal power potentials in the range of 35 GW to 2Ã, TW. Countries that generate more than 15 percent of their electricity from geothermal sources include El Salvador, Kenya, the Philippines, Iceland and Costa Rica.
Geothermal power is considered a sustainable source of renewable energy because its heat extraction is small compared to the geothermal heat of the Earth. Greenhouse gas emissions from geothermal power plants average 45 grams of carbon dioxide per kilowatt-hour of electricity, or less than 5 percent of conventional coal-fired power plants.
Video Geothermal power
History and development
In the 20th century, electricity demand led to consideration of geothermal power as a source of power. Prince Piero Ginori Conti tested the first geothermal power generator on July 4, 1904 in Larderello, Italy. It managed to light four light bulbs. Then, in 1911, the world's first commercial geothermal power plant was built there. The experimental generator was built in Beppu, Japan and Geysers, California, in 1920, but Italy was the only manufacturer of the geothermal power industry in the world until 1958.
In 1958, New Zealand became the second major industrial producer of geothermal electricity when the Wairakei station was commissioned. Wairakei is the first station to use flash steam technology.
In 1960, Pacific Gas and Electric started its first successful geothermal power plant operation in the United States at The Geysers in California. The original turbine lasts for more than 30 years and produces 11 mW clean power.
The binary cycle power plant was first demonstrated in 1967 in Russia and then introduced to the US in 1981, following the energy crisis of the 1970s and significant changes in regulatory policy. This technology allows the use of temperature resources much lower than that previously can be recovered. In 2006, a binary cycle station in Chena Hot Springs, Alaska, came on-line, generating electricity from a record low fluid temperature of 57 Â ° C (135 Â ° F).
Geothermal power stations have recently been built exclusively where high-temperature geothermal resources are available near the surface. The development of a binary cycle power plant and improvements in drilling and extraction technologies can enable geothermal systems to increase in a much larger geographical range. The demonstration project operates in Landau-Pfalz, Germany, and Soultz-sous-ForÃÆ'ªts, France, while previous efforts in Basel, Switzerland were closed after triggering an earthquake. Other pilot projects are in development stage in Australia, the United Kingdom, and the United States.
The thermal efficiency of the geothermal power station is low, about 7-10%, because geothermal liquids are at a low temperature compared to steam from the boiler. With the law of thermodynamics, these low temperatures limit the efficiency of heat engines in extracting useful energy during power generation. Waste heat is wasted, unless it can be used directly and locally, for example in greenhouses, wood mills, and district heating. The efficiency of the system does not affect operational costs as well as for coal or other fossil fuel plants, but that factor influences the station's survival. To generate more energy than the pump consumes, power plants require high geothermal fields and special heat cycles. Since geothermal power does not depend on a variety of energy sources, unlike, for example, wind or solar, the capacity factor can be very large - up to 96% have been demonstrated. However, the global average capacity factor was 74.5% in 2008, according to the IPCC.
Maps Geothermal power
Resources
The Earth's heat content is about 1 ÃÆ' - 10 19 Ã, TJ (2.8 ÃÆ' - 10 15 Ã, TWh ). This heat naturally flows to the surface by conduction at a rate of 44.2 TW and recharged by radioactive decay at a rate of 30 Â ° TW. This power level is more than double the current human energy consumption of primary sources, but most of this power is too diffuse (average about 0.1 W/m 2 ) to be recoverable. The earth's crust effectively acts as a thick insulating blanket that must be penetrated by a liquid ducts (magma, water or other) to release heat below it.
Power plants require high-temperature resources that can only come from underground. Heat must be brought to the surface by fluid circulation, either through magma channels, hot springs, hydrothermal circulation, oil wells, drilled water wells, or a combination of these. This circulation sometimes exists naturally where the crust is thin: magma channels bring heat close to the surface, and hot springs bring heat to the surface. If no hot springs are available, a well should be drilled into a hot aquifer. Far from the plate boundary tectonics, the geothermal gradient is 25-30 Â ° C per kilometer (km) depth in most of the world, so wells must be several kilometers deep to enable power generation. The quantity and quality of recoverable resources increases with drilling depth and proximity to plate tectonic boundaries.
In hot but dry soil, or where water pressure is inadequate, the injected fluid may stimulate production. Developers install two holes to the candidate site, and break the rock between them with explosives or high-pressure water. Then they pump water or liquid carbon dioxide down one drill hole, and another drill hole emerges as a gas. This approach is called geothermal energy hot stones in Europe, or an improved geothermal system in North America. Much greater potential may be available from this approach than from conventional tapping of natural aquifers.
Estimates of geothermal power generation potentials vary from 35 to 2000 GW depending on the scale of the investment. This excludes non-electric heat recovered by cogeneration, geothermal heat pumps and other direct use. A 2006 report by the Massachusetts Institute of Technology (MIT) that includes an improved geothermal system potential estimates that investing $ 1 billion in research and development over the past 15 years will enable the creation of 100 GW of power generation capacity by 2050 in America. Stating itself. The MIT report estimates that over 200 ÃÆ' - 10 9 Ã, TJ (200 ZJ; 5,6 ÃÆ' - 10 7 Ã, TWh) will be able to be extracted, with the potential to increase it to over 2,000 ZJ with technological upgrades - enough to provide all the world's current energy needs for several millennia.
Currently, geothermal wells are rarely more than 3 km (1.9 mi) deep. Estimates of geothermal resources assume wells as deep as 10 km (6.2 miles). This near-depth drilling is now possible in the petroleum industry, although this is an expensive process. The world's deepest research well, the Kola super-drilling hole (KSDB-3), is 12,261 km (7,619 mi) deep. This record was recently replicated by commercial oil wells, such as Exxon Z-12 also in the Chayvo field, Sakhalin. Wells drilled to depths of more than 4 km (2.5 mi) are generally charged for drilling within tens of millions of dollars. The technological challenge is to drill a wide hole at a low cost and break the volume of a larger stone.
Geothermal power is considered sustainable because heat extraction is small compared to geothermal content, but extraction must remain monitored to avoid local depletion. Although geothermal sites are capable of providing heat for decades, individual wells may become cold or run out of water. The three oldest sites, in Larderello, Wairakei, and Geysers have all reduced production from their peak. It is unclear whether these stations extract energy faster than those recharged from larger depths, or whether the aquifers that supply them are depleted. If production is reduced, and water is reinjected, these wells can theoretically restore their full potential. Such mitigation strategies have been implemented on some sites. The long-term viability of geothermal energy has been demonstrated at Lardarello in Italy since 1913, at the Wairakei field in New Zealand since 1958, and on the Geyser field in California since 1960.
Power plant type
Geothermal power plants are similar to other thermal steam turbine power plants whose heat from the fuel source (in the case of geothermal, Earth core) is used to heat water or other working fluids. The working fluid is then used to change the turbine generator, thus generating electricity. The liquid is then cooled and returned to the heat source.
Dry steam power plant
The dry steam station is the simplest and oldest design. This type of power plant is not often found, as it requires resources that produce dry, but most efficient, vapor with the simplest facilities. On these sites, there may be liquid water present in the reservoir, but no water is produced to the surface, only steam. Steam Dry Power uses geothermal steam from 150 Â ° C or greater to rotate the turbine. Because the turbine spins it will generate a generator which then generates electricity and adds an electric field. Then, the steam is emitted to the condenser. Here the vapor turns back into a liquid which then cools the water. Once the water is cooled it flows down the pipe conducting the condensate back into the well, where it can be heated and reproduced. At The Geysers in California, after the first thirty years of power production, the steam supply has run out and the generation is substantially reduced. To restore some of its original capacity, additional water injection was developed during the 1990s and 2000s, including the utilization of effluents from nearby municipal sewage treatment facilities.
Quick thermal power plant
The Flash steam station draws deep and high-pressure hot water to a low-pressure tank and uses the steam generated to drive the turbine. They require a liquid temperature of at least 180 ° C, usually more. This is the most common station type today. Flash steam plants use geothermal reservoirs with temperatures greater than 360 ° C (182 ° C). Hot water flows through wells on the ground under its own pressure. As it flows upwards, the pressure decreases and some of the boiling water becomes steam. The steam is then separated from water and used to power the turbine/generator. Residual water and condensed steam can be injected back into the reservoir, making it a potentially sustainable resource.
Binary cycle power plant
Binary cycle power plants are the latest developments, and can receive liquid temperatures as low as 57 ° C. Geothermal hot enough water is passed by a secondary liquid with a boiling point that is much lower than water. This causes the secondary fluid to flicker to evaporate, which then moves the turbine. This is the most common type of geothermal power station currently under construction. Organic Cycle Rankine and Kalina are used. Thermal efficiency of this type of station is usually about 10-13%.
Worldwide production
The International Geothermal Association (IGA) has reported that 10,715 megawatts (MW) of geothermal power in 24 countries is online, which is expected to generate 67,246 GWh of electricity by 2010. This represents a 20% increase in geothermal power online capacity since 2005. The IGA projected this would grow to 18,500 MW by 2015, due to the number of projects under consideration, often in areas previously assumed to have few resources exploited.
In 2010, the United States led the world in geothermal electricity production with 3,086 MW of installed capacity of 77 power plants; the world's largest geothermal power plant group located in The Geysers, a California geothermal field. The Philippines follows the US as the world's second largest geothermal power producer, with 1,904 MW online capacity; Geothermal power makes up about 27% of power plants in the country.
Al Gore said in The Climate Project Asia Pacific Summit that Indonesia could become a super power country in the production of electricity from geothermal energy. India has announced plans to develop its first geothermal power facility in Chhattisgarh.
Canada is the only major country in the Pacific Ring of Fire that has not yet developed geothermal power. The largest potential region is the Canadian Cordillera, stretching from British Columbia to Yukon, where estimates produce outputs ranging from 1,550 MW to 5,000 MW.
Utility level station
The world's largest geothermal power plant is located in The Geysers, a geothermal field in California, USA. In 2004, five countries (El Salvador, Kenya, Philippines, Iceland and Costa Rica) generated more than 15% of their electricity from geothermal sources.
Geothermal electricity is generated in the 24 countries listed in the table below. During 2005, the contract was placed for an additional 500 MW of electrical capacity in the United States, while there are also stations under construction in 11 other countries. An improved geothermal system several miles deeply operates in France and Germany and is being developed or evaluated in at least four other countries.
Environmental impact
Liquids extracted from deep soil carry a gas mixture, especially carbon dioxide ( CO
2 ), hydrogen sulfide ( H
2 S ), methane ( CH
4 ), ammonia ( NH
3 ) and radon ( Rn ). These pollutants contribute to global warming, acid rain, radiation and bad smell if released.
Existing geothermal stations, which are included in the 50th percentile of all total life cycle emission studies reviewed by the IPCC, produce an average of 45 kg CO
2 eq/MWÃ, Â · h). For comparison, coal-fired power plants emit 1,001 kg of CO2 spins in line-height: per megawatt-hour when it is not combined with carbon capture and storage (CCS).
Stations that experience high levels of acid and volatile chemicals are usually equipped with emission control systems to reduce disposal. Geothermal stations theoretically inject these gases back into the earth, as a form of carbon capture and storage.
In addition to the dissolved gases, hot water from geothermal sources may contain small amounts of toxic chemicals, such as mercury, arsenic, boron, antimony, and salt. These chemicals come out of the solution because the water cools, and can cause environmental damage if released. Modern practice of injecting geothermal fluids back to Earth to stimulate production has the side benefit of reducing this environmental risk.
Station construction may affect soil stability. Subsidence has taken place in the field of Wairakei in New Zealand. An improved geothermal system can trigger earthquakes due to water injection. The project in Basel, Switzerland is suspended because more than 10,000 seismic events measuring up to 3.4 on the Richter Scale occur during the first 6 days of water injections. The risk of geothermal drilling that leads to improvement has been experienced in Staufen im Breisgau.
Geothermal has minimal land and freshwater needs. Geothermal stations use 404 square meters per GWÃ, Â · h versus 3,632 and 1,335 square meters for coal and wind farm facilities respectively. They use 20 liters of fresh water per MWÃ, Â · h compared to more than 1,000 liters per MWMW for nuclear, coal, or oil.
Geothermal power plants can also disrupt the natural cycle of geysers. For example, Beowawe, Nevada geysers, which are geothermal wells that have not been closed, stopped erupting due to the development of dual-flash stations.
Economy
Geothermal power does not require fuel; It is therefore immune to fluctuations in fuel costs. However, capital costs tend to be high. Drilling accounts for more than half the cost, and resource exploration in that it contains significant risks. A typical good doublet in Nevada can support 4.5 megawatt (MW) power plants and cost about $ 10 million to drill, with a 20% failure rate. In total, the construction of power stations and drilling costs of wells is about 2-5 million EUR per MW of electrical capacity, while the measured energy costs are 0.04-0.10 EUR per kWh  · h. Improved geothermal systems tend to be on the high side of this range, with capital costs above $ 4 million per MW and costs trimmed above $ 0.054 per kWh in 2007.
Geothermal power is highly scalable: small power plants can supply rural villages, even though initial capital costs can be high.
The most widely developed geothermal field is Geyser in California. In 2008, this field supports 15 stations, all of which are owned by Calpine, with a total generating capacity of 725 MW.
See also
- Geothermal heating
- Enhanced geothermal system
- Icelandic Distant Drilling Project
- Renewable energy by country
References
External links
- Article on Geothermal Energy
- The Geothermal Collection by the University of Hawaii at Manoa
- GRC Geothermal Library
Source of the article : Wikipedia
0 Comments