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| | Hospitals and clinics the Clash of Clans hack tool; there might be also hack tools for the other games. People young and old can check out everyone hacks and obtain such which they need. It is sure may will have lost of fun once they provide the hack tool at their disposal.<br><br> |
| [[File:ThreeGorgesDam-China2009.jpg|400px|thumb| The 22,500 [[Megawatt|MW]] [[Three Gorges Dam]] in the [[Peoples Republic of China]], the largest hydroelectric power station in the world.]]
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| {{Renewable energy sources}}
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| '''Hydroelectricity''' is the term referring to [[electricity]] generated by [[hydropower]]; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of [[renewable energy]], accounting for 16 percent of global electricity generation – 3,427 terawatt-hours of electricity production in 2010,<ref name=wi2012/> and is expected to increase about 3.1% each year for the next 25 years.
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| Hydropower is produced in 150 countries, with the Asia-Pacific region generating 32 percent of global hydropower in 2010. China is the largest hydroelectricity producer, with 721 terawatt-hours of production in 2010, representing around 17 percent of domestic electricity use. There are now three hydroelectricity plants larger than 10 GW: the [[Three Gorges Dam]] in China, [[Itaipu Dam]] across the Brazil/Paraguay border, and [[Guri Dam]] in Venezuela.<ref name=wi2012>{{cite web |url=http://www.worldwatch.org/node/9527 |title=Use and Capacity of Global Hydropower Increases |author=Worldwatch Institute |date=January 2012 |work= }}</ref>
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| The cost of hydroelectricity is relatively low, making it a competitive source of renewable electricity. The average cost of electricity from a hydro plant larger than 10 megawatts is 3 to 5 U.S. cents per kilowatt-hour.<ref name=wi2012/> Hydro is also a flexible source of electricity since plants can be ramped up and down very quickly to adapt to changing energy demands. However, damming interrupts the flow of rivers and can harm local ecosystems, and building large dams and reservoirs often involves displacing people and wildlife.<ref name=wi2012/> Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably lower output level of the [[greenhouse gas]] [[carbon dioxide]] ({{co2}}) than [[fossil fuel]] powered energy plants.<ref name="REN21-2011">[http://www.ren21.net/Portals/97/documents/GSR/REN21_GSR2011.pdf Renewables 2011 Global Status Report, page 25, Hydropower], ''[[REN21]]'', published 2011, accessed 2011-11-7.</ref>
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| __TOC__
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| {{-}}
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| ==History==
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| [[Hydropower#History|Hydropower]] has been used since ancient times to grind flour and perform other tasks. In the mid-1770s, French engineer [[Bernard Forest de Bélidor]] published ''Architecture Hydraulique'' which described vertical- and horizontal-axis hydraulic machines. By the late 19th century, the [[electrical generator]] was developed and could now be coupled with hydraulics.<ref name="doehis">{{cite web|url=http://www1.eere.energy.gov/water/hydro_history.html|title=History of Hydropower|publisher=U.S. Department of Energy}}</ref> The growing demand for the [[Industrial Revolution]] would drive development as well.<ref name="watenc">{{cite web|title=Hydroelectric Power|url=http://www.waterencyclopedia.com/Ge-Hy/Hydroelectric-Power.html|publisher=Water Encyclopedia}}</ref> In 1878 the world's first hydroelectric power scheme was developed at [[Cragside]] in [[Northumberland]], [[England]] by [[William Armstrong, 1st Baron Armstrong|William George Armstrong]]. It was used to power a single [[arc lamp]] in his art gallery.<ref>{{cite book|title=Industrial archaeology review, Volumes 10-11|year=1987|publisher=Oxford University Press|page=187|url=http://books.google.com/books?id=4xg9AQAAIAAJ&dq=Industrial%20archaeology%20review%3A%20Volumes%2010-11&source=gbs_book_other_versions|author=Association for Industrial Archaeology}}</ref> The old [[Robert Moses Niagara Hydroelectric Power Station#Origins|Schoelkopf Power Station No. 1]] near [[Niagara Falls]] in the U.S. side began to produce electricity in 1881. The first [[Thomas Alva Edison|Edison]] hydroelectric power plant, the [[Vulcan Street Plant]], began operating September 30, 1882, in [[Appleton, Wisconsin]], with an output of about 12.5 kilowatts.<ref>{{cite web|url=http://home.clara.net/darvill/altenerg/hydro.htm|title= Hydroelectric power - energy from falling water|publisher=Clara.net}}</ref> By 1886 there were 45 hydroelectric power plants in the U.S. and Canada. By 1889 there were 200 in the U.S. alone.<ref name="doehis"/>
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| At the beginning of the 20th century, many small hydroelectric power plants were being constructed by commercial companies in mountains near metropolitan areas. [[Grenoble]], France held the [[International Exhibition of Hydropower and Tourism]] with over one million visitors. By 1920 as 40% of the power produced in the United States was hydroelectric, the [[Federal Power Act]] was enacted into law. The Act created the [[Federal Power Commission]] to regulate hydroelectric power plants on federal land and water. As the power plants became larger, their associated dams developed additional purposes to include [[flood control]], [[irrigation]] and [[navigable|navigation]]. Federal funding became necessary for large-scale development and federally owned corporations, such as the [[Tennessee Valley Authority]] (1933) and the [[Bonneville Power Administration]] (1937) were created.<ref name="watenc"/> Additionally, the [[Bureau of Reclamation]] which had began a series of western U.S. irrigation projects in the early 20th century was now constructing large hydroelectric projects such as the 1928 [[Boulder Canyon Project Act|Hoover Dam]].<ref name = "act">{{cite web|title=Boulder Canyon Project Act|url=http://www.usbr.gov/lc/region/g1000/pdfiles/bcpact.pdf|date=December 21, 1928}}</ref> The [[U.S. Army Corps of Engineers]] was also involved in hydroelectric development, completing the [[Bonneville Dam]] in 1937 and being recognized by the [[Flood Control Act of 1936]] as the premier federal flood control agency.<ref name=Arnold>[http://www.usace.army.mil/publications/eng-pamphlets/ep870-1-29/entire.pdf The Evolution of the Flood Control Act of 1936, Joseph L. Arnold, [[United States Army Corps of Engineers]], 1988]</ref>
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| Hydroelectric power plants continued to become larger throughout the 20th century. Hydropower was referred to as ''white coal'' for its power and plenty.<ref>{{cite encyclopedia|encyclopedia=The Book of Knowledge|volume=Vol. 9|page=3220|edition=1945}}</ref> [[Hoover Dam]]'s initial 1,345 MW power plant was the world's largest hydroelectric power plant in 1936; it was eclipsed by the 6809 MW [[Grand Coulee Dam]] in 1942.<ref>{{cite web|url=http://www.a2zlasvegas.com/otherside/sights/hoover.html|title=Hoover Dam and Lake Mead|publisher=U.S. Bureau of Reclamation}}</ref> The [[Itaipu Dam]] opened in 1984 in South America as the largest, producing 14,000 MW but was surpassed in 2008 by the [[Three Gorges Dam]] in China at 22,500 MW. Hydroelectricity would eventually supply some countries, including [[Norway]], [[Democratic Republic of the Congo]], [[Paraguay]] and [[Brazil]], with over 85% of their electricity. The United States currently has over 2,000 hydroelectric power plants that supply 6.4% of its total electrical production output, which is 49% of its renewable electricity.<ref name="watenc"/>
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| ==Generating methods==
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| [[File:Sala de turbinas.jpg|thumb|300px|Turbine row at Los Nihuiles Power Station in [[Mendoza, Argentina|Mendoza]], Argentina]]
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| [[Image:Hydroelectric dam.svg|thumb|300px|Cross section of a conventional hydroelectric dam.]]
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| [[Image:Water turbine.svg|thumb|A typical [[Water turbine|turbine]] and [[electrical generator|generator]]]]
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| ===Conventional (dams)===
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| {{See also|List of conventional hydroelectric power stations}}
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| Most hydroelectric power comes from the [[potential energy]] of [[dam]]med water driving a [[water turbine]] and [[electrical generator|generator]]. The power extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the [[head (hydraulic)|head]]. The amount of [[potential energy]] in water is proportional to the head. A large pipe (the "[[penstock]]") delivers water to the turbine.<ref>[http://www.electricityforum.com/hydroelectricity.html Hydro Electricity Explained]</ref>
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| ===Pumped-storage===
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| {{Main|Pumped-storage hydroelectricity}}
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| {{See also|List of pumped-storage hydroelectric power stations}}
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| This method produces electricity to supply high peak demands by moving water between [[reservoir (water)|reservoirs]] at different elevations. At times of low electrical demand, excess generation capacity is used to pump water into the higher reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine. Pumped-storage schemes currently provide the most commercially important means of large-scale [[grid energy storage]] and improve the daily [[capacity factor]] of the generation system. Pumped storage is not an energy source, and appears as a negative number in listings.<ref>[http://thesouthslope.com/content/pumped-storage-explained Pumped Storage, Explained]</ref>
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| ===Run-of-the-river===
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| {{Main|Run-of-the-river hydroelectricity}}
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| {{See also|List of run-of-the-river hydroelectric power stations}}
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| Run-of-the-river hydroelectric stations are those with small or no reservoir capacity, so that the water coming from upstream must be used for generation at that moment, or must be allowed to bypass the dam. In the United States, run of the river hydropower could potentially provide 60,000 MW (about 13.7% of total use in 2011 if continuously available).<!--total use in 2011 was 3841 billion kWh from Annual Energy Outlook http://www.eia.gov/forecasts/aeo/er/ --><ref>[http://www.renewableenergyworld.com/rea/news/article/2012/01/run-of-the-river-hydropower-goes-with-the-flow Run-of-the-River Hydropower Goes With the Flow]</ref>
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| ===Tide===
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| {{Main|Tide power}}
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| {{See also|List of tidal power stations}}
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| A [[tidal power]] plant makes use of the daily rise and fall of ocean water due to tides; such sources are highly predictable, and if conditions permit construction of reservoirs, can also be [[Dispatchable generation|dispatchable]] to generate power during high demand periods. Less common types of hydro schemes use water's [[kinetic energy]] or undammed sources such as undershot [[water wheel|waterwheels]]. Tidal power is viable in a relatively small number of locations around the world. In Great Britain, there are eight sites that could be developed, which
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| have the potential to generate 20% of the electricity used in 2012.<ref>[http://www.darvill.clara.net/altenerg/tidal.htm Energy Resources: Tidal power]</ref> | |
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| ===Underground===
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| {{Main|Underground power station}}
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| An [[underground power station]] makes use of a large natural height difference between two waterways, such as a waterfall or mountain lake. An underground tunnel is constructed to take water from the high reservoir to the generating hall built in an underground cavern near the lowest point of the water tunnel and a horizontal tailrace taking water away to the lower outlet waterway.[[Image:Tailrace-Forebay-Limestone.JPG|thumb|Measurement of the tailrace and forebay rates at the [[Limestone Generating Station]] in [[Manitoba]], [[Canada]].]]
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| ==Sizes and capacities of hydroelectric facilities==
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| ===Large facilities===
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| {{See also|List of largest power stations in the world|List of largest hydroelectric power stations}}
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| Although no official definition exists for the capacity range of large hydroelectric power stations, facilities from over a few hundred [[megawatt]]s to more than {{nowrap|10 [[Gigawatt|GW]]}} are generally considered large hydroelectric facilities. Currently, only three facilities over {{nowrap|10 [[Gigawatt|GW]]}} ({{nowrap|10,000 [[Megawatt|MW]]}}) are in operation worldwide; [[Three Gorges Dam]] at {{nowrap|22.5 GW}}, [[Itaipu Dam]] at {{nowrap|14 GW}}, and [[Guri Dam]] at {{nowrap|10.2 GW}}. Large-scale hydroelectric power stations are more commonly seen as the largest power producing facilities in the world, with some hydroelectric facilities capable of generating more than double the installed capacities of the current [[List of nuclear power stations|largest nuclear power stations]].
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| {|class="wikitable sortable"
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| ! Rank !! Station !! Country !! [[Geographic coordinate system|Location]] !! Capacity ([[Megawatt|MW]])
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| | 1 || [[Three Gorges Dam]] || {{flag|China}} || {{Coord|30|49|15|N|111|00|08|E|name=Three Gorges Dam}} || 20,300
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| | 2 || [[Itaipu Dam]] || {{flag|Brazil}}<br>{{flag|Paraguay}} || {{Coord|25|24|31|S|54|35|21|W|name=Itaipu Dam}} || 14,000
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| |-
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| | 3 || [[Guri Dam]] || {{flag|Venezuela}} || {{Coord|07|45|59|N|62|59|57|W|name=Guri Dam}} || 10,200
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| |-
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| | 4 || [[Tucurui Dam]] || {{flag|Brazil}} || {{Coord|03|49|53|S|49|38|36|W|name=Tucuruí Dam}} || 8,370
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| |-
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| | 5 || [[Grand Coulee Dam]] || {{flag|United States}} || {{Coord|47|57|23|N|118|58|56|W|name=Grand Coulee Dam}} || 6,809
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| |}
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| {{wide image|Itaipu Décembre 2007 - Vue Générale.jpg|1500px|Panoramic view of the Itaipu Dam, with the spillways (closed at the time of the photo) on the left. In 1994, the [[American Society of Civil Engineers]] elected the Itaipu Dam as one of the seven modern [[Wonders of the World]].<ref>{{Citation
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| | last = Pope
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| | first = Gregory T.
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| | title = The seven wonders of the modern world
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| | newspaper = Popular Mechanics
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| | pages = 48–56
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| | date = December 1995
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| | url = http://books.google.ca/books?id=O2YEAAAAMBAJ&lpg=PA50&dq=itaipu&as_brr=1&pg=PA50#v=onepage&q&f=false}}</ref>
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| }}
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| ===Small===
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| {{Main|Small hydro}}
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| Small hydro is the development of [[hydroelectric power]] on a scale serving a small community or industrial plant. The definition of a small hydro project varies but a generating capacity of up to 10 [[megawatt]]s (MW) is generally accepted as the upper limit of what can be termed small hydro. This may be stretched to 25 MW and 30 MW in [[Canada]] and the [[United States]]. Small-scale hydroelectricity production grew by 28% during 2008 from 2005, raising the total world small-hydro capacity to {{nowrap|85 [[Gigawatt|GW]]}}. Over 70% of this was in [[China]] ({{nowrap|65 GW}}), followed by [[Japan]] ({{nowrap|3.5 GW}}), the [[United States]] ({{nowrap|3 GW}}), and [[India]] ({{nowrap|2 GW}}).<ref>[http://www.ren21.net/globalstatusreport/download/RE_GSR_2006_Update.pdf Renewables Global Status Report 2006 Update], ''[[REN21]]'', published 2006</ref>
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| [[File:Nw vietnam hydro.jpg|thumb|300px|A micro-hydro facility in [[Vietnam]]]]
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| [[File:Amateur Hydroelectricity.jpg|thumb|300px|Pico hydroelectricity in [[Mondulkiri]], [[Cambodia]]]]
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| Small hydro plants may be connected to conventional electrical distribution networks as a source of low-cost renewable energy. Alternatively, small hydro projects may be built in isolated areas that would be uneconomic to serve from a network, or in areas where there is no national electrical distribution network. Since small hydro projects usually have minimal reservoirs and civil construction work, they are seen as having a relatively low environmental impact compared to large hydro. This decreased environmental impact depends strongly on the balance between stream flow and power production.
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| ===Micro===
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| {{Main|Micro hydro}}
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| Micro hydro is a term used for [[hydroelectric power]] installations that typically produce up to {{nowrap|100 [[Kilowatt|kW]]}} of power. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks. There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without purchase of fuel.<ref>{{cite web|url=http://www.tve.org/ho/doc.cfm?aid=1636&lang=English |title=Micro Hydro in the fight against poverty |publisher=Tve.org |date= |accessdate=2012-07-22}}</ref> Micro hydro systems complement [[photovoltaics|photovoltaic]] solar energy systems because in many areas, water flow, and thus available hydro power, is highest in the winter when solar energy is at a minimum.
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| ===Pico===
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| {{Main|Pico hydro}}
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| Pico hydro is a term used for [[hydroelectric power]] generation of under {{nowrap|5 [[Kilowatt|kW]]}}. It is useful in small, remote communities that require only a small amount of electricity. For example, to power one or two fluorescent light bulbs and a TV or radio for a few homes.<ref>{{cite web|url=http://www.t4cd.org/Resources/ICT_Resources/Projects/Pages/ICTProject_287.aspx|title=Pico Hydro Power|publisher=T4cd.org|accessdate=2010-07-16}}</ref> Even smaller turbines of 200-300W may power a single home in a developing country with a drop of only {{Convert|1|m|ft|0|abbr=on}}. Pico-hydro setups typically are [[#Run-of-the-river|run-of-the-river]], meaning that dams are not used, but rather pipes divert some of the flow, drop this down a gradient, and through the turbine before returning it to the stream.
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| ===Calculating available power===
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| {{Main|Hydropower}}
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| A simple formula for approximating electric power production at a hydroelectric plant is: <math> P = \rho hrgk </math>, where
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| *<math>P</math> is Power in watts,
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| *<math>\rho</math> is the density of water (~1000 kg/m<sup>3</sup>),
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| *<math>h</math> is height in meters,
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| *<math>r</math> is flow rate in cubic meters per second,
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| *<math>g</math> is acceleration due to [[gravity]] of 9.8 m/s<sup>2</sup>,
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| *<math>k</math> is a coefficient of efficiency ranging from 0 to 1. Efficiency is often higher (that is, closer to 1) with larger and more modern turbines.
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| Annual electric energy production depends on the available water supply. In some installations the water flow rate can vary by a factor of 10:1 over the course of a year.
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| == Advantages and disadvantages ==
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| {{procon|date=November 2012}}
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| ===Advantages===
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| [[Image:Stwlan.dam.jpg|thumb|The [[Ffestiniog Power Station]] can generate {{nowrap|360 [[Megawatt|MW]]}} of electricity within 60 seconds of the demand arising.]]
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| ====Flexibility====
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| Hydro is a flexible source of electricity since plants can be ramped up and down very quickly to adapt to changing energy demands.<ref name=wi2012/> Hydro turbines have a start-up time of the order of few minutes.<ref name="Huggins2010">{{cite book|author=Robert A. Huggins|title=Energy Storage|url=http://books.google.com/books?id=Nn5y9gQeIlwC&pg=PA60|date=1 September 2010|publisher=Springer|isbn=978-1-4419-1023-3|pages=60}}</ref> It takes around 60 to 90 seconds to bring a unit from cold start-up to full load; this is much shorter than for gas turbines or steam plants.<ref name="SusskindRaseman1970">{{cite book|author1=Herbert Susskind|author2=Chad J. Raseman|title=Combined Hydroelectric Pumped Storage and Nuclear Power Generation|url=http://books.google.com/books?id=zbu5m1Een2sC|year=1970|publisher=Brookhaven National Laboratory|page=15}}</ref> Power generation can also be decreased quickly when there is a surplus power generation.<ref name="Sørensen2004">{{cite book|author=Bent Sørensen|title=Renewable Energy: Its Physics, Engineering, Use, Environmental Impacts, Economy, and Planning Aspects|url=http://books.google.com/books?id=Y17FoN2VUEwC&pg=PA556|year=2004|publisher=Academic Press|isbn=978-0-12-656153-1|pages=556–}}</ref> Hence the limited capacity of hydropower units is not generally used to produce base power except for vacating the flood pool or meeting downstream needs.<ref name="(U.S.)1980">{{cite book|author=Geological Survey (U.S.)|title=Geological Survey Professional Paper|url=http://books.google.com/books?id=37dUAAAAYAAJ&pg=PA10|year=1980|publisher=U.S. Government Printing Office|pages=10}}</ref> Instead, it serves as backup for non-hydro generators.<ref name="Sørensen2004" />
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| ====Low power costs====
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| The major advantage of hydroelectricity is elimination of the cost of fuel. The cost of operating a hydroelectric plant is nearly immune to increases in the cost of [[fossil fuel]]s such as [[Petroleum|oil]], [[natural gas]] or [[coal]], and no imports are needed. The average cost of electricity from a hydro plant larger than 10 megawatts is 3 to 5 U.S. cents per kilowatt-hour.<ref name=wi2012/>
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| Hydroelectric plants have long economic lives, with some plants still in service after 50–100 years.<ref>[http://reme.epfl.ch/webdav/site/reme/users/106542/public/SHS4/Gr01.pdf Hydropower – A Way of Becoming Independent of Fossil Energy?]{{Dead link|date=July 2010}}</ref> Operating labor cost is also usually low, as plants are automated and have few personnel on site during normal operation.
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| Where a dam serves multiple purposes, a hydroelectric plant may be added with relatively low construction cost, providing a useful revenue stream to offset the costs of dam operation. It has been calculated that the sale of electricity from the [[Three Gorges Dam]] will cover the construction costs after 5 to 8 years of full generation.<ref>{{cite web|url=http://www.waterpowermagazine.com/story.asp?storyCode=2041318 |title=Beyond Three Gorges in China |publisher=Waterpowermagazine.com |date=2007-01-10}}</ref>
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| ====Suitability for industrial applications====
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| While many hydroelectric projects supply public electricity networks, some are created to serve specific [[industry|industrial]] enterprises. Dedicated hydroelectric projects are often built to provide the substantial amounts of electricity needed for [[aluminium]] electrolytic plants, for example. The [[Grand Coulee Dam]] switched to support [[Alcoa]] aluminium in [[Bellingham, Washington]], [[United States]] for American [[World War II]] airplanes before it was allowed to provide irrigation and power to citizens (in addition to aluminium power) after the war. In [[Suriname]], the [[Brokopondo Reservoir]] was constructed to provide electricity for the [[Alcoa]] aluminium industry. [[New Zealand|New Zealand's]] [[Manapouri Power Station]] was constructed to supply electricity to the [[aluminium]] [[smelter]] at [[Comalco|Tiwai Point]].
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| ====Reduced CO2 emissions====
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| Since hydroelectric dams do not burn fossil fuels, they are claimed to not directly produce [[carbon dioxide]]. While some carbon dioxide is produced during manufacture and construction of the project, this is a tiny fraction of the operating emissions of equivalent fossil-fuel electricity generation. One measurement of greenhouse gas related and other externality comparison between energy sources can be found in the ExternE project by the [[Paul Scherrer Institut]] and the [[University of Stuttgart]] which was funded by the [[European Commission]].<ref name="ExternEFTR">{{cite web|url=http://www.externe.info/expoltec.pdf|title=Final Technical Report, Version 2|author=Rabl A. et. al.|date=August 2005|work=Externalities of Energy: Extension of Accounting Framework and Policy Applications|publisher=European Commission}}</ref> According to that study, hydroelectricity produces the least amount of [[greenhouse gases]] and [[externality]] of any energy source.<ref name="ExternEGraphs">{{cite web|url=http://gabe.web.psi.ch/projects/externe_pol/index.html|title=External costs of electricity systems (graph format)|year=2005|work=ExternE-Pol|publisher=Technology Assessment / GaBE ([[Paul Scherrer Institut]])}}</ref> Coming in second place was [[wind energy|wind]], third was [[Nuclear power|nuclear energy]], and fourth was [[solar energy|solar]] [[photovoltaic]].<ref name="ExternEGraphs"/> The low [[greenhouse gas]] impact of hydroelectricity is found especially in [[temperate climate]]s. The above study was for local energy in [[Europe]]; presumably similar conditions prevail in North America and Northern Asia, which all see a regular, natural freeze/thaw cycle (with associated seasonal plant decay and regrowth). Greater greenhouse gas emission impacts are found in the tropical regions, the lower [[latitude]] regions of the earth, as it has been noted that the reservoirs of power plants in tropical regions produce a larger amount of the greenhouse gas [[methane]].<ref>http://www.nature.com/ngeo/journal/v4/n9/full/ngeo1226.html</ref>
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| ====Other uses of the reservoir====
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| Reservoirs created by hydroelectric schemes often provide facilities for [[List of water sports|water sports]], and become tourist attractions themselves. In some countries, [[aquaculture]] in reservoirs is common. [[Multipurpose reservoir|Multi-use dams]] installed for [[irrigation]] support [[agriculture]] with a relatively constant water supply. Large hydro dams can control floods, which would otherwise affect people living downstream of the project.<ref name="Water: Science and Issues">{{cite journal|last=Atkins|first=William|title=Hydroelectric Power|journal=Water: Science and Issues|year=2003|volume=2|pages=187–191}}</ref>
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| ===Disadvantages===
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| ====Ecosystem damage and loss of land====
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| [[File:MeroweDam01.jpg|thumb|Hydroelectric power stations that use [[dam]]s would submerge large areas of land due to the requirement of a [[reservoir]].]]
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| Large reservoirs required for the operation of hydroelectric power stations result in submersion of extensive areas upstream of the dams, destroying biologically rich and productive lowland and riverine valley forests, marshland and grasslands. The loss of land is often exacerbated by [[habitat fragmentation]] of surrounding areas caused by the reservoir.<ref>{{cite journal|last=Robbins|first=Paul|title=Hydropower|journal=Encyclopedia of Environment and Society|year=2007|volume=3}}</ref>
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| Hydroelectric projects can be disruptive to surrounding aquatic [[ecosystem]]s both upstream and downstream of the plant site. Generation of hydroelectric power changes the downstream river environment. Water exiting a turbine usually contains very little suspended sediment, which can lead to scouring of river beds and loss of riverbanks.<ref>{{cite web|url=http://internationalrivers.org/en/node/1476|title=Sedimentation Problems with Dams|publisher=Internationalrivers.org|accessdate=2010-07-16}}</ref> Since turbine gates are often opened intermittently, rapid or even daily fluctuations in river flow are observed.
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| ====Siltation and flow shortage====
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| When water flows it has the ability to transport particles heavier than itself downstream. This has a negative effect on dams and subsequently their power stations, particularly those on rivers or within catchment areas with high siltation. [[Siltation]] can fill a reservoir and reduce its capacity to control floods along with causing additional horizontal pressure on the upstream portion of the dam. Eventually, some reservoirs can become full of sediment and useless or over-top during a flood and fail.<ref>{{cite web|last=Patrick James|first=H Chansen|title=Teaching Case Studies in Reservoir Siltation and Catchment Erosion|url=http://www.ijee.dit.ie/articles/Vol14-4/ijee1012.pdf|publisher=TEMPUS Publications|location=Great Britain|pages=265–275|year=1998}}</ref><ref>{{cite book|last=Șentürk|first=Fuat|title=Hydraulics of dams and reservoirs|year=1994|publisher=Water Resources Publications|location=Highlands Ranch, Colo.|isbn=0-918334-80-2|edition=reference.|page=375}}</ref>
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| | |
| Changes in the amount of river flow will correlate with the amount of energy produced by a dam. Lower river flows will reduce the amount of live storage in a reservoir therefore reducing the amount of water that can be used for hydroelectricity. The result of diminished river flow can be power shortages in areas that depend heavily on hydroelectric power. The risk of flow shortage may increase as a result of [[climate change]].<ref name=ODI1>Frauke Urban and Tom Mitchell 2011. [http://www.odi.org.uk/resources/details.asp?id=5792&title=climate-change-disasters-electricity-generation Climate change, disasters and electricity generation]. London: [[Overseas Development Institute]] and [[Institute of Development Studies]]</ref> One study from the [[Colorado River]] in the United States suggest that modest climate changes, such as an increase in temperature in 2 degree Celsius resulting in a 10% decline in precipitation, might reduce river run-off by up to 40%.<ref name=ODI1/> [[Brazil]] in particular is vulnerable due to its heaving reliance on hydroelectricity, as increasing temperatures, lower water flow and alterations in the rainfall regime, could reduce total energy production by 7% annually by the end of the century.<ref name=ODI1/>
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| ====Methane emissions (from reservoirs)====
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| [[File:Hoover Dam Nevada Luftaufnahme.jpg|thumb|The [[Hoover Dam]] in the [[United States]] is a large conventional dammed-hydro facility, with an installed capacity of {{nowrap|2,080 [[Megawatt|MW]]}}.]]
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| {{See also|Environmental impacts of reservoirs}}
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| Lower positive impacts are found in the tropical regions, as it has been noted that the reservoirs of power plants in tropical regions produce substantial amounts of [[methane]]. This is due to plant material in flooded areas decaying in an [[Hypoxia (environmental)|anaerobic]] environment, and forming methane, a [[greenhouse gas]]. According to the [[World Commission on Dams]] report,<ref>{{cite web|url=http://www.dams.org/report/|title=WCD Findal Report|publisher=Dams.org|date=2000-11-16}}</ref> where the reservoir is large compared to the generating capacity (less than 100 watts per square metre of surface area) and no clearing of the forests in the area was undertaken prior to impoundment of the reservoir, greenhouse gas emissions from the reservoir may be higher than those of a conventional oil-fired thermal generation plant.<ref>{{cite web|url=http://www.newscientist.com/article.ns?id=dn7046|title=Hydroelectric power's dirty secret revealed|publisher=Newscientist.com}}</ref>
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| | |
| In [[Boreal forest|boreal]] reservoirs of Canada and Northern Europe, however, greenhouse gas emissions are typically only 2% to 8% of any kind of conventional fossil-fuel thermal generation. A new class of underwater logging operation that targets drowned forests can mitigate the effect of forest decay.<ref>{{cite web|url=http://inhabitat.com/2006/12/01/rediscovered-wood-the-triton-sawfish/#more-1973|title="Rediscovered" Wood & The Triton Sawfish|publisher=Inhabitat|date=2006-11-16}}</ref>
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| ====Relocation====
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| Another disadvantage of hydroelectric dams is the need to relocate the people living where the reservoirs are planned. In 2000, the World Commission on Dams estimated that dams had physically displaced 40-80 million people worldwide.<ref>{{cite web|url=http://internationalrivers.org/en/way-forward/world-commission-dams/world-commission-dams-framework-brief-introduction|title=Briefing of World Commission on Dams|publisher=Internationalrivers.org|date=2008-02-29}}</ref>
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| ====Failure risks====
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| {{See also|Dam failure|List of hydroelectric power station failures}}
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| Because large conventional dammed-hydro facilities hold back large volumes of water, a failure due to poor construction, natural disasters or sabotage can be catastrophic to downriver settlements and infrastructure. Dam failures have been some of the largest man-made disasters in history.
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| | |
| The [[Banqiao Dam]] failure in Southern China directly resulted in the deaths of 26,000 people, and another 145,000 from epidemics. Millions were left homeless. Also, the creation of a dam in a geologically inappropriate location may cause disasters such as 1963 disaster at [[Vajont Dam]] in Italy, where almost 2000 people died.<ref>References may be found in the list of [[Dam failure]]s.</ref>
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| Smaller dams and [[micro hydro]] facilities create less risk, but can form continuing hazards even after being decommissioned. For example, the small [[Kelly Barnes Dam]] failed in 1967, causing 39 deaths with the Toccoa Flood, ten years after its power plant was decommissioned.<ref>[http://ga.water.usgs.gov/news/historical-toccoa/ Toccoa Flood] USGS Historical Site, retrieved 02sep2009</ref>
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| ===Comparison with other methods of power generation===
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| Hydroelectricity eliminates the [[flue gas emissions from fossil fuel combustion]], including pollutants such as [[sulfur dioxide]], [[nitric oxide]], [[carbon monoxide]], dust, and [[mercury (element)|mercury]] in the [[coal]]. Hydroelectricity also avoids the hazards of [[coal mining]] and the indirect health effects of coal emissions. Compared to [[nuclear power]], hydroelectricity generates no [[nuclear waste]], has none of the dangers associated with [[uranium mining]], nor [[Nuclear and radiation accidents|nuclear leaks]].
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| Compared to [[wind farm]]s, hydroelectricity power plants have a more predictable load factor. If the project has a storage reservoir, it can generate power when needed. Hydroelectric plants can be easily regulated to follow variations in power demand.
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| ==World hydroelectric capacity==
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| [[File:Ren2008.svg|thumb|300px|World renewable energy share (2008)]]
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| [[File:Top 5 Hydropower-Producing Countries.png|thumb|Trends in the top five hydroelectricity-producing countries]]
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| {{See also|List of countries by electricity production from renewable sources|Cost of electricity by source}}
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| The ranking of hydro-electric capacity is either by actual annual energy production or by installed capacity power rating. Hydro accounted for 16 percent of global electricity consumption, and 3,427 terawatt-hours of electricity production in 2010, which continues the rapid rate of increase experienced between 2003 and 2009.<ref name=wi2012/>
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| | |
| Hydropower is produced in 150 countries, with the Asia-Pacific region generated 32 percent of global hydropower in 2010. China is the largest hydroelectricity producer, with 721 terawatt-hours of production in 2010, representing around 17 percent of domestic electricity use. [[Brazil]], [[Canada]], [[New Zealand]], [[Norway]], [[Paraguay]], [[Austria]], [[Switzerland]], and [[Venezuela]] have a majority of the internal electric energy production from hydroelectric power. [[Paraguay]] produces 100% of its electricity from hydroelectric dams, and exports 90% of its production to Brazil and to Argentina. [[Norway]] produces 98–99% of its electricity from hydroelectric sources.<ref name=norway/>
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| There are now three hydroelectric plants larger than 10 GW: the [[Three Gorges Dam]] in China, [[Itaipu Dam]] across the Brazil/Paraguay border, and [[Guri Dam]] in Venezuela.<ref name="wi2012"/>
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| A hydro-electric plant rarely operates at its full power rating over a full year; the ratio between annual average power and installed capacity rating is the [[capacity factor]]. The installed capacity is the sum of all generator nameplate power ratings.<ref>[http://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/reports_and_publications/statistical_energy_review_2009/STAGING/local_assets/downloads/spreadsheets/statistical_review_full_report_workbook_2009.xls#'Hydro Consumption BP.com]{{Dead link|date=July 2010}}</ref>
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| {| class="wikitable sortable" style="margin:auto;"
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| |+ Ten of the largest hydroelectric producers as at 2009.<ref name=norway>{{cite news |first= |last= |authorlink= |coauthors= |title=Binge and purge |url=http://www.economist.com/displaystory.cfm?story_id=12970769 |quote=98-99% of Norway’s electricity comes from hydroelectric plants. |work=[[The Economist]] |accessdate=2009-01-30 |date=2009-01-22}}</ref><ref>{{cite web|title=Indicators 2009, National Electric Power Industry|url=http://www.sdpc.gov.cn/tztg/W020100106306926853623.doc|publisher=Chinese Government|accessdate=18 July 2010}}</ref>
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| |-
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| ! Country !! Annual hydroelectric<br>production ([[TWh]]) !! Installed<br>capacity ([[Gigawatt|GW]]) !! Capacity<br>factor !! % of total <br>capacity
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| |-
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| | {{flag|China}} || 652.05 || 196.79 || 0.37 || 22.25
| |
| |-
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| | {{flag|Canada}} || 369.5 || 88.974 || 0.59 || 61.12
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| |-
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| | {{flag|Brazil}} || 363.8 || 69.080 || 0.56 || 85.56
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| |-
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| | {{flag|United States}} || 250.6 || 79.511 || 0.42 || 5.74
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| |-
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| | {{flag|Russia}} || 167.0 || 45.000 || 0.42 || 17.64
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| |-
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| | {{flag|Norway}} || 140.5 || 27.528 || 0.49 || 98.25
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| |-
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| | {{flag|India}} || 115.6 || 33.600 || 0.43 || 15.80
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| |-
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| | {{flag|Venezuela}} || 85.96 || 14.622 || 0.67 || 69.20
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| |-
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| | {{flag|Japan}} || 69.2 || 27.229 || 0.37 || 7.21
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| |-
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| | {{flag|Sweden}} || 65.5 || 16.209 || 0.46 || 44.34
| |
| |}
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| | |
| ==Major projects under construction==
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| {| class="wikitable sortable"
| |
| |-
| |
| ! Name
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| ! Maximum Capacity
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| ! Country
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| ! Construction started
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| ! Scheduled completion
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| ! Comments
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| |-
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| |[[Xiluodu Dam]]
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| |12,600 MW
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| |[[People's Republic of China|China]]
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| |December 26, 2005
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| |2015
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| |Construction once stopped due to lack of environmental impact study.
| |
| |-
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| |[[Belo Monte Dam]]
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| |11,181 MW
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| |[[Brazil]]
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| |March, 2011
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| |2015
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| |Preliminary construction underway.<ref>{{cite web|title=Belo Monte hydroelectric dam construction work begins|url=http://www.guardian.co.uk/environment/2011/mar/10/belo-monte-hydroelectric-work|publisher=Guardian UK|accessdate=2 April 2011|date=10 March 2011}}</ref>
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| Construction suspended by court order Aug 2012<ref>{{cite web|title= Belo Monte dam construction halted by Brazilian court|url=http://www.guardian.co.uk/world/2012/aug/16/belo-monte-dam-construction-suspended|publisher=Guardian UK|accessdate=24 August 2012|date=16 August 2012}}</ref>
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| |-
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| |[[Siang Upper HE Project]]
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| |11,000 MW
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| |[[India]]
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| |April, 2009
| |
| |2024
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| |Multi-phase construction over a period of 15 years. Construction was delayed due to dispute with China.<ref>{{cite web|url=http://www.thehindubusinessline.com/2006/03/24/stories/2006032401830500.htm |title=Upper Siang project likely to be relocated on Chinese concerns |publisher=Thehindubusinessline.com |date=2006-03-24 |accessdate=2012-07-22}}</ref>
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| |-
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| |[[TaSang Dam]]
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| |7,110 MW
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| |[[Burma]]
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| |March, 2007
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| |2022
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| |Controversial 228 meter tall dam with capacity to produce 35,446 GWh annually.
| |
| |-
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| |[[Xiangjiaba Dam]]
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| |6,400 MW
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| |[[People's Republic of China|China]]
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| |November 26, 2006
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| |2015
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| |
| |
| |-
| |
| |[[Grand Ethiopian Renaissance Dam]]
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| |6,000 MW
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| |[[Ethiopia]]
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| |2011
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| |2017
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| | Located in the upper Nile Basin, drawing complaint from Egypt
| |
| |-
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| |[[Nuozhadu Dam]]
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| |5,850 MW
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| |[[People's Republic of China|China]]
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| |2006
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| |2017
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| |
| |
| |-
| |
| |[[Jinping 2 Hydropower Station]]
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| |4,800 MW
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| |[[People's Republic of China|China]]
| |
| |January 30, 2007
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| |2014
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| |To build this dam, 23 families and 129 local residents need to be moved. It works with [[Jinping 1 Hydropower Station]] as a group.
| |
| |-
| |
| |[[Diamer-Bhasha Dam]]
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| |4,500 MW
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| |[[Pakistan]]
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| |October 18, 2011
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| |2023
| |
| |
| |
| |-
| |
| |[[Jinping 1 Hydropower Station]]
| |
| |3,600 MW
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| |[[People's Republic of China|China]]
| |
| |November 11, 2005
| |
| |2014
| |
| |
| |
| |-
| |
| |[[Jirau Dam]]
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| |3,300 MW
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| |[[Brazil]]
| |
| |2008
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| |2013
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| |Construction halted in March 2011 due to worker riots.<ref>{{cite web|title=Brazil Sends Forces to Jirau Dam After Riots|url=http://online.wsj.com/article/SB10001424052748704608504576208640384691826.html|publisher=Wall Street Journal|accessdate=2 April 2011|date=18 March 2011}}</ref>
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| |-
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| |[[Guanyinyan Dam]]
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| |3,000 MW
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| |[[People's Republic of China|China]]
| |
| |2008
| |
| |2015
| |
| |Construction of the roads and spillway started.
| |
| |-
| |
| |[[Lianghekou Dam]]<ref>{{cite web|url=http://www.ehdc.com.cn/newsite/DisplayNewsMaster/ShowNews.aspx?Id=1175 |title=二滩水电开发有限责任公司 |publisher=Ehdc.com.cn |date=2009-04-25 |accessdate=2012-07-22}}</ref>
| |
| |3,000 MW
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| |[[People's Republic of China|China]]
| |
| |2009
| |
| |2015
| |
| |
| |
| |-
| |
| |[[Dagangshan Dam]]
| |
| |2,600 MW
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| |[[People's Republic of China|China]]
| |
| |August 15, 2008<ref>http://www.cb600.cn/info_view.asp?id=1357280</ref>
| |
| |2014
| |
| |
| |
| |-
| |
| |[[Liyuan Dam]]
| |
| |2,400 MW
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| |[[People's Republic of China|China]]
| |
| |2008<ref>{{cite web|url=http://zt.xxgk.yn.gov.cn/canton_model12/newsview.aspx?id=368628 |title=陆良县人口和计划生育局 |publisher=Zt.xxgk.yn.gov.cn |date= |accessdate=2012-07-22}}</ref>
| |
| |2013
| |
| |
| |
| |-
| |
| |[[Tocoma Dam]] [[Bolívar (state)|Bolívar State]]
| |
| |2,160 MW
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| |[[Venezuela]]
| |
| |2004
| |
| |2014
| |
| |This power plant would be the last development in the Low Caroni Basin, bringing the total to six power plants on the same river, including the 10,000MW [[Guri (Simón Bolívar)|Guri Dam]].<ref>{{cite web|url=http://idbgroup.org/exr/doc98/pro/pvel1003-06eng.pdf|format=PDF|title=Caroní River Watershed Management Plan|last=Staff|year=2004|publisher=Inter-America Development Bank|accessdate=2008-10-25}} {{Dead link|date=November 2010|bot=H3llBot}}</ref>
| |
| |-
| |
| |[[Ludila Dam]]
| |
| |2,100 MW
| |
| |[[People's Republic of China|China]]
| |
| |2007
| |
| |2015
| |
| |Construction halt due to lack of the environmental assessment.
| |
| |-
| |
| |[[Shuangjiangkou Dam]]
| |
| |2,000 MW
| |
| |[[People's Republic of China|China]]
| |
| |December, 2007<ref>[http://www.cjwsjy.com.cn/News/Company/200808055706.htm CJWSJY.com.cn]{{dead link|date=July 2012}}</ref>
| |
| |2018
| |
| |The dam will be 312 m high.
| |
| |-
| |
| |[[Ahai Dam]]
| |
| |2,000 MW
| |
| |[[People's Republic of China|China]]
| |
| |July 27, 2006
| |
| |2015
| |
| |
| |
| |-
| |
| |[[Teles Pires Dam]]
| |
| |1,820 MW
| |
| |[[Brazil]]
| |
| |2011
| |
| |2015
| |
| |
| |
| |-
| |
| |[[Lower Subansiri Dam]]
| |
| |2,000 MW
| |
| |[[India]]
| |
| |2005
| |
| |2014
| |
| |
| |
| |}
| |
| | |
| ==See also==
| |
| {{portal|Renewable energy|Energy}}
| |
| * [[Hydraulic engineering]]
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| * [[International Rivers]]
| |
| * [[List of energy storage projects]]
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| * [[List of hydroelectric power station failures]]
| |
| * [[List of hydroelectric power stations]]
| |
| * [[List of largest power stations in the world]]
| |
| * [[Xcel Company Fire|Xcel Energy Cabin Creek Hydroelectric Plant Fire]]
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| | |
| ==References==
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| {{Reflist|30em}}
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| | |
| ==External links==
| |
| {{Commons category}}
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| *[http://www.hydropower.org/ International Hydropower Association]
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| *{{dmoz|Science/Technology/Energy/Renewable/Hydro/}}
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| *[http://www.hydro.org/ National Hydropower Association, USA]
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| *[http://www.hydroreform.org/ Hydropower Reform Coalition]
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| *[http://www.dameffects.org/ Interactive demonstration on the effects of dams on rivers]
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| *[http://www.esha.be/ European Small Hydropower Association]
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| *[http://www.iec.ch/dyn/www/f?p=103:7:0::::FSP_ORG_ID,FSP_LANG_ID:1228,25 IEC TC 4: Hydraulic turbines] (International Electrotechnical Commission - Technical Committee 4) IEC TC 4 portal with access to scope, documents and [http://tc4.iec.ch/index-tc4.html TC 4 website]
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| {{Electricity generation}}
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| {{Hydropower}}
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| {{Energy country lists}}
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| [[Category:Hydroelectricity| ]]
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| [[Category:Landscape]]
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| [[Category:Sustainable technologies]]
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| {{Link FA|hr}}
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| {{Link FA|scn}}
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