60-601: The Wairakei Power Station is a geothermal power station near the Wairakei Geothermal Field in New Zealand . Wairakei lies in the Taupō Volcanic Zone . The power station was built in 1958, the first of its type (wet steam) in the world, and it is currently owned and operated by Contact Energy . A binary cycle power plant was constructed in 2005 to use lower-temperature steam that had already gone through
120-546: A light bulb with a power rating of 100 W is turned on for one hour, the energy used is 100 watt hours (W·h), 0.1 kilowatt hour, or 360 kJ . This same amount of energy would light a 40-watt bulb for 2.5 hours, or a 50-watt bulb for 2 hours. Power stations are rated using units of power, typically megawatts or gigawatts (for example, the Three Gorges Dam in China is rated at approximately 22 gigawatts). This reflects
180-462: A 20% failure rate. In total, electrical station construction and well drilling costs about 2–5 million € per MW of electrical capacity, while the levelised energy cost is 0.04–0.10 € per kW·h. Enhanced geothermal systems tend to be on the high side of these ranges, with capital costs above $ 4 million per MW and levelized costs above $ 0.054 per kW·h in 2007. Research suggests in-reservoir storage could increase
240-531: A coal-fired power plant emits 1,001 kg of CO 2 equivalent per megawatt-hour when not coupled with carbon capture and storage (CCS). As many geothermal projects are situated in volcanically active areas that naturally emit greenhouse gases, it is hypothesized that geothermal plants may actually decrease the rate of de-gassing by reducing the pressure on underground reservoirs. Stations that experience high levels of acids and volatile chemicals are usually equipped with emission-control systems to reduce
300-620: A combination of these. This circulation sometimes exists naturally where the crust is thin: magma conduits bring heat close to the surface, and hot springs bring the heat to the surface. If a hot spring is not available, a well must be drilled into a hot aquifer . Away from tectonic plate boundaries the geothermal gradient is 25–30 °C per kilometre (km) of depth in most of the world, so wells would have to be several kilometres deep to permit electricity generation. The quantity and quality of recoverable resources improves with drilling depth and proximity to tectonic plate boundaries. In ground that
360-419: A generator, thereby producing electricity. The fluid is then cooled and returned to the heat source. Dry steam stations are the simplest and oldest design. There are few power stations of this type, because they require a resource that produces dry steam , but they are the most efficient, with the simplest facilities. At these sites, there may be liquid water present in the reservoir, but only steam, not water,
420-412: A source of renewable energy for both power and heating, geothermal has the potential to meet 3 to 5% of global demand by 2050. With economic incentives , it is estimated that by 2100 it will be possible to meet 10% of global demand with geothermal power. In the 20th century, demand for electricity led to the consideration of geothermal power as a generating source. Prince Piero Ginori Conti tested
480-581: A source of renewable energy. In 1960, Pacific Gas and Electric began operation of the first successful geothermal electric power station in the United States at The Geysers in California. The original turbine lasted for more than 30 years and produced 11 MW net power. An organic fluid based binary cycle power station was first demonstrated in 1967 in the Soviet Union and later introduced to
540-493: A total generating capacity of 725 MW. Terawatt The watt (symbol: W ) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m ⋅s . It is used to quantify the rate of energy transfer . The watt is named in honor of James Watt (1736–1819), an 18th-century Scottish inventor , mechanical engineer , and chemist who improved
600-535: A turbine, which generates 648 MW e (i.e. electricity). Other SI prefixes are sometimes used, for example gigawatt electrical (GW e ). The International Bureau of Weights and Measures , which maintains the SI-standard, states that further information about a quantity should not be attached to the unit symbol but instead to the quantity symbol (e.g., P th = 270 W rather than P = 270 W th ) and so these unit symbols are non-SI. In compliance with SI,
660-424: A unit of time, namely 1 J/s. In this new definition, 1 absolute watt = 1.00019 international watts. Texts written before 1948 are likely to be using the international watt, which implies caution when comparing numerical values from this period with the post-1948 watt. In 1960, the 11th General Conference on Weights and Measures adopted the absolute watt into the International System of Units (SI) as
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#1732851916080720-512: Is considered to be sustainable because the heat extraction is small compared to the Earth's heat content, but extraction must still be monitored to avoid local depletion. Although geothermal sites are capable of providing heat for many decades, individual wells may cool down or run out of water. The three oldest sites, at Larderello, Wairakei , and the Geysers have all reduced production from their peaks. It
780-527: Is currently used in 26 countries, while geothermal heating is in use in 70 countries. As of 2019, worldwide geothermal power capacity amounts to 15.4 gigawatts (GW), of which 23.9% (3.68 GW) are installed in the United States . International markets grew at an average annual rate of 5 percent over the three years to 2015, and global geothermal power capacity is expected to reach 14.5–17.6 GW by 2020. Based on current geologic knowledge and technology
840-505: Is extracted is originally cold rainwater that had percolated downwards and been heated by hot rock; pumping back the warm water that emerges from the exhaust of the generator system thus reduces the heat drawn from the ground. The majority of arsenic in the Waikato River comes from the geothermal power station with the concentration reaching 0.035 grams of arsenic per cubic metre in certain places. The amount of arsenic gradually declines as
900-686: Is hot but dry, or where water pressure is inadequate, injected fluid can stimulate production. Developers bore two holes into a candidate site, and fracture the rock between them with explosives or high-pressure water . Then they pump water or liquefied carbon dioxide down one borehole, and it comes up the other borehole as a gas. This approach is called hot dry rock geothermal energy in Europe, or enhanced geothermal systems in North America. Much greater potential may be available from this approach than from conventional tapping of natural aquifers. Estimates of
960-700: Is named after the Scottish inventor James Watt . The unit name was proposed by C. William Siemens in August 1882 in his President's Address to the Fifty-Second Congress of the British Association for the Advancement of Science . Noting that units in the practical system of units were named after leading physicists, Siemens proposed that watt might be an appropriate name for a unit of power. Siemens defined
1020-423: Is not clear whether these stations extracted energy faster than it was replenished from greater depths, or whether the aquifers supplying them are being depleted. If production is reduced, and water is reinjected, these wells could theoretically recover their full potential. Such mitigation strategies have already been implemented at some sites. The long-term sustainability of geothermal energy has been demonstrated at
1080-516: Is now possible in the petroleum industry, although it is an expensive process. The deepest research well in the world, the Kola Superdeep Borehole (KSDB-3), is 12.261 km (7.619 mi) deep. Wells drilled to depths greater than 4 km (2.5 mi) generally incur drilling costs in the tens of millions of dollars. The technological challenges are to drill wide bores at low cost and to break larger volumes of rock. Geothermal power
1140-679: Is passed by a secondary fluid with a much lower boiling point than water. This causes the secondary fluid to flash vaporize, which then drives the turbines. This is the most common type of geothermal electricity station being constructed today. Both Organic Rankine and Kalina cycles are used. The thermal efficiency of this type of station is typically about 10–13%. Binary cycle power plants have an average unit capacity of 6.3 MW, 30.4 MW at single-flash power plants, 37.4 MW at double-flash plants, and 45.4 MW at power plants working on superheated steam. The International Renewable Energy Agency has reported that 14,438 megawatts (MW) of geothermal power
1200-464: Is possible as a result of the work of the geothermal circulation systems. However, according to an estimation given by Leningrad Mining Institute in 1980s, possible cool-down will be negligible compared to natural climate fluctuations. While volcanic activity produces geothermal energy, it is also risky. As of 2022 the Puna Geothermal Venture has still not returned to full capacity after
1260-509: Is produced to the surface. Dry steam power directly uses geothermal steam of 150 °C or greater to turn turbines. As the turbine rotates it powers a generator that produces electricity and adds to the power field. Then, the steam is emitted to a condenser, where it turns back into a liquid, which then cools the water. After the water is cooled it flows down a pipe that conducts the condensate back into deep wells, where it can be reheated and produced again. At The Geysers in California, after
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#17328519160801320-523: Is the rate at which electrical work is performed when a current of one ampere (A) flows across an electrical potential difference of one volt (V), meaning the watt is equivalent to the volt-ampere (the latter unit, however, is used for a different quantity from the real power of an electrical circuit). 1 W = 1 V ⋅ A . {\displaystyle \mathrm {1~W=1~V{\cdot }A} .} Two additional unit conversions for watt can be found using
1380-515: Is too diffuse (approximately 0.1 W/m on average) to be recoverable. The Earth's crust effectively acts as a thick insulating blanket which must be pierced by fluid conduits (of magma , water or other) to release the heat underneath. Electricity generation requires high-temperature resources that can only come from deep underground. The heat must be carried to the surface by fluid circulation, either through magma conduits , hot springs , hydrothermal circulation , oil wells , drilled water wells, or
1440-689: Is uniquely suited for geothermal power production. Japan has numerous hot springs that could provide fuel for geothermal power plants, but a massive investment in Japan's infrastructure would be necessary. The largest group of geothermal power plants in the world is located at The Geysers , a geothermal field in California , United States . As of 2021, five countries ( Kenya , Iceland , El Salvador , New Zealand , and Nicaragua) generate more than 15% of their electricity from geothermal sources. The following table lists these data for each country: Data are for
1500-449: The 2018 lower Puna eruption . Geothermal power requires no fuel; it is therefore immune to fuel cost fluctuations. However, capital costs tend to be high. Drilling accounts for over half the costs, and exploration of deep resources entails significant risks. A typical well doublet in Nevada can support 4.5 megawatts (MW) of electricity generation and costs about $ 10 million to drill, with
1560-731: The Geothermal Energy Association (GEA) publicly discloses, the GEA estimates that only 6.9% of total global potential has been tapped so far, while the IPCC reported geothermal power potential to be in the range of 35 GW to 2 TW . Countries generating more than 15 percent of their electricity from geothermal sources include El Salvador , Kenya , the Philippines , Iceland , New Zealand , and Costa Rica . Indonesia has an estimated potential of 29 GW of geothermal energy resources,
1620-811: The Newcomen engine with his own steam engine in 1776. Watt's invention was fundamental for the Industrial Revolution . When an object's velocity is held constant at one meter per second against a constant opposing force of one newton , the rate at which work is done is one watt. 1 W = 1 J / s = 1 N ⋅ m / s = 1 k g ⋅ m 2 ⋅ s − 3 . {\displaystyle \mathrm {1~W=1~J{/}s=1~N{\cdot }m{/}s=1~kg{\cdot }m^{2}{\cdot }s^{-3}} .} In terms of electromagnetism , one watt
1680-590: The United Kingdom , and the United States of America . The thermal efficiency of geothermal electric stations is low, around 7–10%, because geothermal fluids are at a low temperature compared with steam from boilers. By the laws of thermodynamics this low temperature limits the efficiency of heat engines in extracting useful energy during the generation of electricity. Exhaust heat is wasted, unless it can be used directly and locally, for example in greenhouses, timber mills, and district heating. The efficiency of
1740-612: The Larderello field in Italy since 1913, at the Wairakei field in New Zealand since 1958, and at the Geysers field in California since 1960. Geothermal power stations are similar to other steam turbine thermal power stations in that heat from a fuel source (in geothermal's case, the Earth's core) is used to heat water or another working fluid . The working fluid is then used to turn a turbine of
1800-551: The United States in 1981 , following the 1970s energy crisis and significant changes in regulatory policies. This technology allows the use of temperature resources as low as 81 °C. In 2006, a binary cycle station in Chena Hot Springs, Alaska , came on-line, producing electricity from a record low fluid temperature of 57 °C (135 °F). Geothermal electric stations have until recently been built exclusively where high-temperature geothermal resources are available near
1860-467: The above equation and Ohm's law . 1 W = 1 V 2 / Ω = 1 A 2 ⋅ Ω , {\displaystyle \mathrm {1~W=1~V^{2}/\Omega =1~A^{2}{\cdot }\Omega } ,} where ohm ( Ω {\displaystyle \Omega } ) is the SI derived unit of electrical resistance . The watt
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1920-579: The creation of 100 GW of electrical generating capacity by 2050 in the United States alone. The MIT report estimated that over 200 × 10 TJ (200 ZJ; 5.6 × 10 TWh) would be extractable, with the potential to increase this to over 2,000 ZJ with technology improvements – sufficient to provide all the world's present energy needs for several millennia . At present, geothermal wells are rarely more than 3 km (1.9 mi) deep. Upper estimates of geothermal resources assume wells as deep as 10 km (6.2 mi). Drilling near this depth
1980-405: The economic viability of enhanced geothermal systems in energy systems with a large share of variable renewable energy sources. Geothermal power is highly scalable: a small power station can supply a rural village, though initial capital costs can be high. The most developed geothermal field is the Geysers in California. In 2008, this field supported 15 stations, all owned by Calpine , with
2040-532: The electricity generating potential of geothermal energy vary from 35 to 2000 GW depending on the scale of investments. This does not include non-electric heat recovered by co-generation, geothermal heat pumps and other direct use. A 2006 report by the Massachusetts Institute of Technology (MIT) that included the potential of enhanced geothermal systems estimated that investing US$ 1 billion in research and development over 15 years would allow
2100-515: The energy company Ørsted A/S uses the unit megawatt for produced electrical power and the equivalent unit megajoule per second for delivered heating power in a combined heat and power station such as Avedøre Power Station . When describing alternating current (AC) electricity, another distinction is made between the watt and the volt-ampere . While these units are equivalent for simple resistive circuits , they differ when loads exhibit electrical reactance . Radio stations usually report
2160-486: The entire Hawke's Bay and Gisborne regions and half of the Bay of Plenty region. A 33 kV connection at the substation supplies Unison Networks ' Taupō distribution network. Geothermal power Geothermal power is electrical power generated from geothermal energy . Technologies in use include dry steam power stations, flash steam power stations and binary cycle power stations. Geothermal electricity generation
2220-789: The exhaust. Geothermal stations can also inject these gases back into the earth as a form of carbon capture and storage, such as in New Zealand and in the CarbFix project in Iceland. Other stations like the Kızıldere geothermal power plant , exhibit the capability to utilize geothermal fluids to process carbon dioxide gas into dry ice at two nearby plants resulting in very little environmental impact. In addition to dissolved gases, hot water from geothermal sources may hold in solution trace amounts of toxic chemicals, such as mercury , arsenic , boron , antimony , and salt. These chemicals come out of solution as
2280-502: The field has had a number of visible effects on the local environment. Visible geothermal activity has increased (due to changes in the water table / water pressure allowing more steam to be created underground, upsurging at places like Craters of the Moon ), while there has also been some land subsidence and reduction in steam volumes from the field after some decades of use. Recent total electrical production has been sustained or increased with
2340-400: The first 30 years of power production, the steam supply had depleted and generation was substantially reduced. To restore some of the former capacity, supplemental water injection was developed during the 1990s and 2000s, including utilization of effluent from nearby municipal sewage treatment facilities. Flash steam stations pull deep, high-pressure hot water into lower-pressure tanks and use
2400-517: The first geothermal power generator on 4 July 1904 in Larderello, Italy . It successfully lit four light bulbs. Later, in 1911, the world's first commercial geothermal power station was built there. Experimental generators were built in Beppu, Japan and the Geysers, California , in the 1920s, but Italy was the world's only industrial producer of geothermal electricity until 1958. In 1958, New Zealand became
2460-425: The global average capacity factor was 74.5% in 2008, according to the IPCC . The Earth's heat content is about 1 × 10 TJ (2.8 × 10 TWh) . This heat naturally flows to the surface by conduction at a rate of 44.2 TW and is replenished by radioactive decay at a rate of 30 TW. These power rates are more than double humanity's current energy consumption from primary sources, but most of this power
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2520-407: The hot water is transformed into steam. The steam is then separated from the water and used to power a turbine/generator. Any leftover water and condensed steam may be injected back into the reservoir, making this a potentially sustainable resource. Binary cycle power stations are the most recent development, and can accept fluid temperatures as low as 57 °C. The moderately hot geothermal water
2580-438: The investment in additional power stations such as the binary plant of 2005 designed for lower-temperature generation, but the total still does not reach the early power levels such as the 192MW reported in 1965 (NZED Annual Statistics), for instance. Some power stations in the field are now capped in their extraction capacities and a substantial part of the water / steam is being reinjected after use. The hot geothermal fluid that
2640-491: The largest in the world; in 2017, its installed capacity was 1.8 GW. Geothermal power is considered to be a sustainable , renewable source of energy because the heat extraction is small compared with the Earth's heat content . The greenhouse gas emissions of geothermal electric stations average 45 grams of carbon dioxide per kilowatt-hour of electricity, or less than 5% of those of conventional coal-fired plants. As
2700-555: The main plant. This increased the total capacity of the power station to 181 MW. The Wairakei power station is due to be phased out in 2026, replaced by the Te Mihi geothermal power station . The Poihipi Power Station was built in 1996 at a nearby site in the same field. Wairakei A station Units 2, 3, 5 and 6 were decommissioned in 1984. Wairakei B station Wairakei Unit 14 – 4 MW intermediate/low pressure Wairakei Binary Plant – 14 MW binary The use of steam from
2760-460: The maximum power output it can achieve at any point in time. A power station's annual energy output, however, would be recorded using units of energy (not power), typically gigawatt hours. Major energy production or consumption is often expressed as terawatt hours for a given period; often a calendar year or financial year. One terawatt hour of energy is equal to a sustained power delivery of one terawatt for one hour, or approximately 114 megawatts for
2820-488: The power of their transmitters in units of watts, referring to the effective radiated power . This refers to the power that a half-wave dipole antenna would need to radiate to match the intensity of the transmitter's main lobe . The terms power and energy are closely related but distinct physical quantities. Power is the rate at which energy is generated or consumed and hence is measured in units (e.g. watts) that represent energy per unit time . For example, when
2880-745: The publicly owned electricity sector in India announced a plan to develop the country's first geothermal power facility in the landlocked state of Chhattisgarh . Geothermal power in Canada has high potential due to its position on the Pacific Ring of Fire . The region of greatest potential is the Canadian Cordillera , stretching from British Columbia to the Yukon , where estimates of generating output have ranged from 1,550 MW to 5,000 MW. The geography of Japan
2940-420: The resulting flashed steam to drive turbines. They require fluid temperatures of at least 180 °C, usually more. This is the most common type of station in operation today. Flash steam plants use geothermal reservoirs of water with temperatures greater than 360 °F (182 °C). The hot water flows up through wells in the ground under its own pressure. As it flows upward, the pressure decreases and some of
3000-529: The river flows northwards and is at its lowest at the Waikato River Heads. Also at Wairakei is a major electrical substation, owned by the national grid operator Transpower . The substation is a major switching point for the Central North Island, and is responsible for connecting more than half the country's geothermal power stations, several hydroelectric power stations, the electricity supply to
3060-404: The second major industrial producer of geothermal electricity when its Wairakei station was commissioned. Wairakei was the first station to use flash steam technology. Over the past 60 years, net fluid production has been in excess of 2.5km . Subsidence at Wairakei-Tauhara has been an issue in a number of formal hearings related to environmental consents for expanded development of the system as
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#17328519160803120-611: The surface. The development of binary cycle power plants and improvements in drilling and extraction technology may enable enhanced geothermal systems over a much greater geographical range. Demonstration projects are operational in Landau-Pfalz , Germany, and Soultz-sous-Forêts , France, while an earlier effort in Basel , Switzerland was shut down after it triggered earthquakes. Other demonstration projects are under construction in Australia ,
3180-493: The system does not affect operational costs as it would for a coal or other fossil fuel plant, but it does factor into the viability of the station. In order to produce more energy than the pumps consume, electricity generation requires high-temperature geothermal fields and specialized heat cycles. Because geothermal power does not rely on variable sources of energy, unlike, for example, wind or solar, its capacity factor can be quite large – up to 96% has been demonstrated. However
3240-559: The unit of power. In the electric power industry , megawatt electrical ( MWe or MW e ) refers by convention to the electric power produced by a generator, while megawatt thermal or thermal megawatt (MWt, MW t , or MWth, MW th ) refers to thermal power produced by the plant. For example, the Embalse nuclear power plant in Argentina uses a fission reactor to generate 2,109 MW t (i.e. heat), which creates steam to drive
3300-556: The unit within the existing system of practical units as "the power conveyed by a current of an Ampère through the difference of potential of a Volt". In October 1908, at the International Conference on Electric Units and Standards in London, so-called international definitions were established for practical electrical units. Siemens' definition was adopted as the international watt. (Also used: 1 A × 1 Ω.) The watt
3360-511: The water cools, and can cause environmental damage if released. The modern practice of injecting geothermal fluids back into the Earth to stimulate production has the side benefit of reducing this environmental risk. Station construction can adversely affect land stability. Subsidence has occurred in the Wairakei field in New Zealand. Enhanced geothermal systems can trigger earthquakes due to water injection. The project in Basel , Switzerland
3420-541: The year 2021. Data are sourced from the EIA . Only includes countries with more than 0.01 TWh of generation. Links for each location go to the relevant geothermal power page, when available. Existing geothermal electric stations, that fall within the 50th percentile of all total life cycle emissions studies reviewed by the IPCC , produce on average 45 kg of CO 2 equivalent emissions per megawatt-hour of generated electricity (kg CO 2 eq/ MW·h ). For comparison,
3480-420: Was defined as equal to 10 units of power in the practical system of units. The "international units" were dominant from 1909 until 1948. After the 9th General Conference on Weights and Measures in 1948, the international watt was redefined from practical units to absolute units (i.e., using only length, mass, and time). Concretely, this meant that 1 watt was defined as the quantity of energy transferred in
3540-541: Was online worldwide at the end of 2020, generating 94,949 GWh of electricity. In theory, the world's geothermal resources are sufficient to supply humans with energy. However, only a tiny fraction of the world's geothermal resources can at present be explored on a profitable basis. Al Gore said in The Climate Project Asia Pacific Summit that Indonesia could become a super power country in electricity production from geothermal energy. In 2013
3600-717: 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. The risk of geothermal drilling leading to uplift has been experienced in Staufen im Breisgau . Geothermal has minimal land and freshwater requirements. Geothermal stations use 404 square meters per GW·h versus 3,632 and 1,335 square meters for coal facilities and wind farms respectively. They use 20 litres of freshwater per MW·h versus over 1000 litres per MW·h for nuclear, coal, or oil. Local climate cooling
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