View source for Hydroelectricity

{{short description|Electricity generated by hydropower}}
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{{Update|date=January 2022|reason=IEA 2021 report https://www.iea.org/reports/hydropower-special-market-report}}

[[File:ThreeGorgesDam-China2009.jpg|upright=1.35|thumb|The [[Three Gorges Dam]] in [[Central China]] is the [[List of largest power stations in the world#Top 20 largest power producing facilities|world's largest]] power-producing facility of any kind.]]

'''Hydroelectricity''', or '''hydroelectric power''', is [[Electricity generation|electricity generated]] from [[hydropower]] (water power). Hydropower supplies one sixth of the world's [[electricity]], almost 4,500 [[TWh]] in 2020, which is more than all other [[Renewable energy|renewable source]]s combined and also more than [[nuclear power]].<ref name=":4" /> Hydropower can provide large amounts of [[Low-carbon power|low-carbon electricity]] on demand, making it a key element for creating secure and clean electricity supply systems.<ref name=":4" /> A hydroelectric power station that has a dam and [[reservoir]] is a flexible source, since the amount of electricity produced can be increased or decreased in seconds or minutes in response to varying electricity demand. Once a hydroelectric complex is constructed, it produces no direct waste, and almost always emits considerably less [[greenhouse gas]] than [[fossil fuel]]-powered energy plants.<ref name="REN21-2011">[http://www.ren21.net/Portals/0/documents/Resources/GSR2011_FINAL.pdf Renewables 2011 Global Status Report, page 25, Hydropower], ''[[REN21]]'', published 2011, accessed 2016-02-19.</ref> However, when constructed in lowland [[rainforest]] areas, where part of the forest is inundated, substantial amounts of greenhouse gases may be emitted.<ref>{{Cite journal |last1=de Faria |first1=Felipe A M |last2=Jaramillo |first2=Paulina |last3=Sawakuchi |first3=Henrique O |last4=Richey |first4=Jeffrey E |last5=Barros |first5=Nathan |date=2015-12-01 |title=Estimating greenhouse gas emissions from future Amazonian hydroelectric reservoirs |journal=Environmental Research Letters |volume=10 |issue=12 |pages=124019 |doi=10.1088/1748-9326/10/12/124019 |issn=1748-9326|doi-access=free }}</ref>

Construction of a hydroelectric complex can have significant environmental impact, principally in loss of [[arable land]] and population displacement.<ref>{{Cite journal |last=Fearnside |first=Philip M. |date=1989-07-01 |title=Brazil's Balbina Dam: Environment versus the legacy of the Pharaohs in Amazonia |url=https://doi.org/10.1007/BF01867675 |journal=Environmental Management |language=en |volume=13 |issue=4 |pages=401–423 |doi=10.1007/BF01867675 |s2cid=154405904 |issn=1432-1009}}</ref><ref>{{Cite news |last=Yardley |first=Jim |date=2007-11-19 |title=Chinese Dam Projects Criticized for Their Human Costs |language=en-US |work=The New York Times |url=https://www.nytimes.com/2007/11/19/world/asia/19dam.html |access-date=2023-04-21 |issn=0362-4331}}</ref> They also disrupt the natural ecology of the river involved, affecting habitats and ecosystems, and siltation and erosion patterns. While dams can ameliorate the risks of flooding, [[dam failure]] can be catastrophic.

In 2021, global installed hydropower electrical capacity reached almost 1,400 GW, the highest among all renewable energy technologies.<ref name=":5">IEA (2022), Renewables 2022, IEA, Paris https://www.iea.org/reports/renewables-2022, License: CC BY 4.0</ref> Hydroelectricity plays a leading role in countries like Brazil, Norway and China.<ref name="BP">{{cite web |title=BP Statistical Review 2019 |url=https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2019-full-report.pdf |access-date=28 March 2020}}</ref> but there are geographical limits and environmental issues.<ref>{{cite news |date=5 November 2018 |title=Large hydropower dams not sustainable in the developing world |work=BBC News |url=https://www.bbc.com/news/science-environment-46098118 |access-date=27 March 2020}}</ref> [[Tidal power]] can be used in coastal regions.

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==History==
{{See also|Hydropower#History}}
[[File:Hidroelektrana na Đetinji 01.jpg|thumb|upright=1.15|Museum Hydroelectric power plant "Under the Town" in [[Užice]], [[Serbia]], built in 1900.<ref>[https://books.google.com/books?id=-x9NHOLSnNUC&dq=One+of+the+oldest+hydroelectric+power+plants+built+on+tesla+principles&pg=PA397 ''One of the Oldest Hydroelectric Power Plants in Europa Built on Tesla's Principels''], Explorations in the History of Machines and Mechanisms: Proceedings of HMM2012, Teun Koetsier and Marco Ceccarelli, 2012.</ref>]]

Hydropower has been used since ancient times to grind flour and perform other tasks. In the late 18th century hydraulic power provided the energy source needed for the start of the [[Industrial Revolution]]. In the mid-1770s, French engineer [[Bernard Forest de Bélidor]] published ''Architecture Hydraulique'', which described vertical- and horizontal-axis hydraulic machines, and in 1771 [[Richard Arkwright]]'s combination of [[Water wheel|water power]], the [[water frame]], and [[continuous production]] played a significant part in the development of the factory system, with modern employment practices.<ref>Maxine Berg, ''The age of manufactures, 1700-1820: Industry, innovation and work in Britain'' (Routledge, 2005).</ref> In the 1840s the [[hydraulic power network]] was developed to generate and transmit hydro power to end users.

By the late 19th century, the [[electrical generator]] was developed and could now be coupled with hydraulics.<ref name="doehis">{{cite web |url=https://www.energy.gov/eere/water/history-hydropower|title=History of Hydropower|publisher=U.S. Department of Energy}}</ref> The growing demand arising from 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 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=https://books.google.com/books?id=4xg9AQAAIAAJ&q=Industrial%20archaeology%20review%3A%20Volumes%2010-11 |author=Association for Industrial Archaeology}}</ref>  The old [[Robert Moses Niagara Hydroelectric Power Station#Origins|Schoelkopf Power Station No. 1]], US, near [[Niagara Falls]], began to produce electricity in 1881. The first [[Thomas Alva Edison|Edison]] hydroelectric power station, 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 stations in the United States and Canada; and by 1889 there were 200 in the United States alone.<ref name="doehis"/>

[[File:Warwick Castle - Engine House, Waterwheel, Weir, and Old Castle Bridge.jpg|thumb|upright=1.15|The [[Warwick Castle]] water-powered generator house, used for the generation of electricity for the castle from 1894 until 1940]]
At the beginning of the 20th century, many small hydroelectric power stations 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 1925. By 1920, when 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 stations on federal land and water. As the power stations became larger, their associated dams developed additional purposes, including [[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 begun a series of western US 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|url-status=dead|archive-url=https://web.archive.org/web/20110613142851/http://www.usbr.gov/lc/region/g1000/pdfiles/bcpact.pdf|archive-date=June 13, 2011}}</ref> The [[United States 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 {{webarchive|url=https://web.archive.org/web/20070823024822/http://www.usace.army.mil/publications/eng-pamphlets/ep870-1-29/entire.pdf |date=2007-08-23 }}</ref>

Hydroelectric power stations continued to become larger throughout the 20th century. Hydropower was referred to as "white coal".<ref>{{cite encyclopedia|encyclopedia=The Book of Knowledge|title=Hydropower|volume=9|page=3220|edition=1945}}</ref> [[Hoover Dam]]'s initial {{nowrap|1,345 MW}} power station was the world's largest hydroelectric power station in 1936; it was eclipsed by the {{nowrap|6,809 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 {{nowrap|14 GW}}, but was surpassed in 2008 by the [[Three Gorges Dam]] in China at {{nowrap|22.5 GW}}. Hydroelectricity would eventually supply some countries, including [[Norway]], [[Democratic Republic of the Congo]], [[Paraguay]] and [[Brazil]], with over 85% of their electricity.

==Future potential==
In 2021 the International Energy Agency (IEA) said that more efforts are needed to help [[Climate change mitigation|limit climate change]].<ref>{{Cite web|title=Hydropower – Analysis|url=https://www.iea.org/reports/hydropower|access-date=2022-01-30|website=IEA|language=en-GB}}</ref> Some countries have highly developed their hydropower potential and have very little room for growth: Switzerland produces 88% of its potential and Mexico 80%.<ref name=":3">{{cite web|url=http://www.iea.org/publications/freepublications/publication/hydropower_essentials.pdf|title=Renewable Energy Essentials: Hydropower|website=IEA.org|publisher=[[International Energy Agency]]|access-date=2017-01-16|archive-url=https://web.archive.org/web/20170329132409/http://www.iea.org/publications/freepublications/publication/hydropower_essentials.pdf|archive-date=2017-03-29|url-status=dead}}</ref> In 2022, the IEA released a main-case forecast of 141 GW generated by hydropower over 2022–2027, which is slightly lower than deployment achieved from 2017–2022. Because environmental permitting and construction times are long, they estimate hydropower potential will remain limited, with only an additional 40 GW deemed possible in the accelerated case.<ref name=":5" />

=== Modernization of existing infrastructure ===
In 2021 the IEA said that major modernisation refurbishments are required.<ref name=":4">{{Cite web|title=Hydropower Special Market Report – Analysis|url=https://www.iea.org/reports/hydropower-special-market-report|access-date=2022-01-30|website=IEA|language=en-GB}}</ref>{{Rp|page=67}}

==Generating methods==
{{multiple images
| align     = right
| width     = 200
| direction = vertical
| image1    = Hydroelectric dam.svg
| caption1  = Cross-section of a conventional hydroelectric dam
| image2    = Castaic Power Plant Front.jpg
| caption2  = Pumped-storage
| image3    = LwrGrDam2.jpg 
| caption3  = Run-of-the-river
| image4    = Barrage de la Rance.jpg
| caption4  = Tidal
}}

===Conventional (dams)===
{{See also|List of conventional hydroelectric power stations}}
Most hydroelectric power comes from the [[potential energy]] of [[dam]]med water driving a [[water turbine]] and [[electric 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]]. A large pipe (the "[[penstock]]") delivers water from the [[reservoir]] to the turbine.<ref>{{Cite web|url=https://www.electricityforum.com/hydroelectricity|title=Hydroelectricity - Renewable Energy Generation|website=www.electricityforum.com}}</ref>

===Pumped-storage===
{{Main|Pumped-storage hydroelectricity}}
{{See also|List of pumped-storage hydroelectric power stations}}
This method produces electricity to supply high peak demands by moving water between [[reservoir]]s at different elevations. At times of low electrical demand, the excess generation capacity is used to pump water into the higher reservoir, thus providing [[Energy demand management|demand side response]].<ref name=":4" /> When the demand becomes greater, water is released back into the lower reservoir through a turbine. In 2021 pumped-storage schemes provided almost 85% of the world's 190 GW of [[grid energy storage]]<ref name=":4" /> 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>{{Cite web|url=http://thesouthslope.com/content/pumped-storage-explained|archiveurl=https://web.archive.org/web/20121231233454/http://thesouthslope.com/content/pumped-storage-explained|url-status=dead|title=Pumped Storage, Explained|archivedate=December 31, 2012}}</ref>

===Run-of-the-river===
{{Main|Run-of-the-river hydroelectricity}}
{{See also|List of run-of-the-river hydroelectric power stations}}
Run-of-the-river hydroelectric stations are those with small or no reservoir capacity, so that only the water coming from upstream is available for generation at that moment, and any oversupply must pass unused. A constant supply of water from a lake or existing reservoir upstream is a significant advantage in choosing sites for run-of-the-river.<ref>{{cite web|url=https://www.renewableenergyworld.com/baseload/run-of-the-river-hydropower-goes-with-the-flow/|title=Run-of-the-River Hydropower Goes With the Flow|date=31 January 2012}}</ref>

===Tide===
{{Main|Tide power}}
{{See also|List of tidal power stations}}
A [[tidal power]] station 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]]s. Tidal power is viable in a relatively small number of locations around the world.<ref>{{Cite web|url=http://www.darvill.clara.net/altenerg/tidal.htm|title=Energy Resources: Tidal power|website=www.darvill.clara.net}}</ref>

==Sizes, types and capacities of hydroelectric facilities==

===Large facilities===
{{See also|List of largest power stations|List of largest hydroelectric power stations}}

The largest power producers in the world are hydroelectric power stations, 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]].

Although no official definition exists for the capacity range of large hydroelectric power stations, facilities from over a few hundred [[megawatt]]s are generally considered large hydroelectric facilities.

Currently, only seven facilities over {{nowrap|10 [[Gigawatt|GW]]}} ({{nowrap|10,000 [[Megawatt|MW]]}}) are in operation worldwide, see table below.<ref name=wi2012>{{cite web |url=https://www.power-technology.com/features/worlds-biggest-hydroelectric-power-plants/ |title=World's biggest hydroelectric power plants |author=Hemanth Kumar |date=March 2021 |access-date=2022-02-05 }}</ref>

{|class="wikitable"
|-
! Rank !! width=150 | Station !! width=150 | Country !! [[Geographic coordinate system|Location]] !! Capacity ([[Megawatt|MW]])
|-
| align=center | 1. || [[Three Gorges Dam]] || {{flag|China}} || {{Coord|30|49|15|N|111|00|08|E|name=Three Gorges Dam}} || align=center | 22,500
|-
| align=center | 2. || [[Baihetan Dam]] || {{flag|China}} || {{Coord|27|13|23|N|102|54|11|E|name=Three Gorges Dam}} || align=center | 16,000
|-
| align="center" | 3. || [[Itaipu Dam]]|| {{flag|Brazil}}<br />{{flag|Paraguay}} || {{Coord|25|24|31|S|54|35|21|W|name=Itaipu Dam}} || align="center" | 14,000
|-
| align="center" | 4. ||[[Xiluodu Dam]]|| {{flag|China}} || {{Coord|28|15|35|N|103|38|58|E|name=Xiluodu Dam}} || align="center" | 13,860
|-
| align="center" | 5. || [[Belo Monte Dam]]|| {{flag|Brazil}} || {{Coord|03|06|57|S|51|47|45|W|name=Belo Monte Dam}} || align="center" | 11,233
|-
| align="center" | 6. || [[Guri Dam]] || {{flag|Venezuela}} || {{Coord|07|45|59|N|62|59|57|W|name=Guri Dam}} || align="center" | 10,235
|-
| align=center | 7. || [[Wudongde Dam]] || {{flag|China}} || {{Coord|26|20|2|N|102|37|48|E|name=Three Gorges Dam}} || align=center | 10,200
|}

{{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 Wonders of the Modern World]].<ref>{{Citation| last = Pope| first = Gregory T.| title = The seven wonders of the modern world| newspaper = Popular Mechanics| pages = 48–56| date = December 1995| url = https://books.google.com/books?id=O2YEAAAAMBAJ&q=itaipu&pg=PA50}}</ref>
}}

===Small===
{{Main|Small hydro}}

Small hydro is [[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. This may be stretched to {{nowrap|25 MW}} and {{nowrap|30 MW}} in [[Canada]] and the United States.<ref>[http://www.ren21.net/globalstatusreport/download/RE_GSR_2006_Update.pdf Renewables Global Status Report 2006 Update] {{webarchive |url=https://web.archive.org/web/20110718181410/http://www.ren21.net/globalstatusreport/download/RE_GSR_2006_Update.pdf |date=July 18, 2011 }}, ''[[REN21]]'', published 2006</ref><ref>[http://www.ren21.net/Portals/0/documents/activities/gsr/RE_GSR_2009_Update.pdf Renewables Global Status Report 2009 Update] {{webarchive |url=https://web.archive.org/web/20110718181410/http://www.ren21.net/globalstatusreport/download/RE_GSR_2006_Update.pdf |date=July 18, 2011 }}, ''[[REN21]]'', published 2009</ref>

[[File:Nw vietnam hydro.jpg|thumb|upright=1.35|A micro-hydro facility in [[Vietnam]]]]
[[File:Amateur Hydroelectricity.jpg|thumb|upright=1.35|Pico hydroelectricity in [[Mondulkiri]], [[Cambodia]]]]
Small hydro stations 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 grid, 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.{{Citation needed|date=May 2022}}

===Micro===
{{Main|Micro hydro}}

Micro hydro means [[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 |access-date=2012-07-22 |url-status=dead |archive-url=https://web.archive.org/web/20120426092643/http://tve.org/ho/doc.cfm?aid=1636&lang=English |archive-date=2012-04-26 }}</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.

===Pico===
{{Main|Pico hydro}}

Pico hydro is [[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, the 1.1&nbsp;kW [[Intermediate Technology Development Group]] Pico Hydro Project in Kenya supplies 57 homes with very small electric loads (e.g., a couple of lights and a phone charger, or a small TV/radio).<ref>{{cite web|url=http://www.t4cd.org/Resources/ICT_Resources/Projects/Pages/ICTProject_287.aspx|title=Pico Hydro Power|publisher=T4cd.org|access-date=2010-07-16|url-status=dead|archive-url=https://web.archive.org/web/20090731064419/http://www.t4cd.org/Resources/ICT_Resources/Projects/Pages/ICTProject_287.aspx|archive-date=2009-07-31}}</ref> Even smaller turbines of 200–300&nbsp;W may power a few homes in a developing country with a drop of only {{Convert|1|m|ft|0|abbr=on}}. A Pico-hydro setup is typically [[#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.

===Underground===
{{Main|Underground power station}}

An [[underground power station]] is generally used at large facilities and makes use of a large natural height difference between two waterways, such as a waterfall or mountain lake. A tunnel is constructed to take water from the high reservoir to the generating hall built in a cavern near the lowest point of the water tunnel and a horizontal tailrace taking water away to the lower outlet waterway.[[File:Tailrace-Forebay-Limestone.JPG|thumb|Measurement of the tailrace and forebay rates at the [[Limestone Generating Station]] in [[Manitoba]], [[Canada]].]]

===Calculating available power===
{{Main|Hydropower}}
A simple formula for approximating electric power production at a hydroelectric station is:

<math> P = -\eta \ (\dot{m} g \ \Delta h) = -\eta \ ((\rho \dot{V}) \  g \ \Delta h)</math>

where
* <math>P</math> is [[Power (physics)|power]] (in [[watt]]s)
* <math>\eta</math> ([[Eta (Greek letter)|eta]]) is the coefficient of efficiency (a unitless, scalar coefficient, ranging from 0 for completely inefficient to 1 for completely efficient).
* <math>\rho</math> ([[Rho (Greek letter)|rho]]) is the [[density]] of water (~1000&nbsp;[[Kilogram|kg]]/[[Cubic meter|m<sup>3</sup>]])
* <math>\dot{V}</math> is the [[volumetric flow rate]] (in m<sup>3</sup>/s)
* <math>\dot{m}</math> is the [[mass flow rate]] (in kg/s)
* <math>\Delta h</math> ([[Delta (Greek letter)|Delta]] h) is the change in height (in [[meter]]s)
* <math>g</math> is [[Standard gravity|acceleration due to gravity]] (9.8&nbsp;m/s<sup>2</sup>)

Efficiency is often higher (that is, closer to 1) with larger and more modern turbines. 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.{{Citation needed|date=January 2022}}

==Properties==

===Advantages===
[[File:Stwlan.dam.jpg|thumb|The [[Ffestiniog Power Station]] can generate {{nowrap|360 [[Megawatt|MW]]}} of electricity within 60 seconds of the demand arising.]]

====Flexibility====
Hydropower is a flexible source of electricity since stations 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 a few minutes.<ref name="Huggins2010">{{cite book|author=Robert A. Huggins|title=Energy Storage|url=https://books.google.com/books?id=Nn5y9gQeIlwC&pg=PA60|date=1 September 2010|publisher=Springer|isbn=978-1-4419-1023-3|pages=60}}</ref> Although [[Battery storage power station|battery power]] is quicker its capacity is tiny compared to hydro.<ref name=":4" /> It takes less than 10 minutes to bring most hydro units from cold start-up to full load; this is quicker than nuclear and almost all fossil fuel power.<ref>{{Cite web|title=About 25% of U.S. power plants can start up within an hour - Today in Energy - U.S. Energy Information Administration (EIA)|url=https://www.eia.gov/todayinenergy/detail.php?id=45956|access-date=2022-01-30|website=www.eia.gov}}</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=https://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=https://books.google.com/books?id=37dUAAAAYAAJ&pg=PA10|year=1980|publisher=U.S. Government Printing Office|pages=10}}</ref> Instead, it can serve as backup for non-hydro generators.<ref name="Sørensen2004" />

====High value power====
The major advantage of conventional hydroelectric dams with reservoirs is their ability to store water at low cost for [[Dispatchable generation|dispatch later]] as high value clean electricity. In 2021, the IEA estimated that the "reservoirs of all existing conventional hydropower plants combined can store a total of 1,500 terawatt-hours (TWh) of electrical energy in one full cycle" which was "about 170 times more energy than the global fleet of pumped storage hydropower plants".<ref name=":4" /> Battery storage capacity is not expected to overtake pumped storage during the 2020s.<ref name=":4" /> When used as [[Peaking power plant|peak power]] to meet demand, hydroelectricity has a higher value than [[Base load|baseload power]] and a much higher value compared to [[intermittent energy source]]s such as wind and solar.

Hydroelectric stations 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?]  {{webarchive |url=https://web.archive.org/web/20080528070938/http://reme.epfl.ch/webdav/site/reme/users/106542/public/SHS4/Gr01.pdf |date=28 May 2008 }}</ref> Operating labor cost is also usually low, as plants are automated and have few personnel on site during normal operation.

Where a dam serves multiple purposes, a hydroelectric station 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 |url-status=dead |archive-url=https://web.archive.org/web/20110614050746/http://www.waterpowermagazine.com/story.asp?storyCode=2041318 |archive-date=2011-06-14 }}</ref> However, some data shows that in most countries large hydropower dams will be too costly and take too long to build to deliver a positive risk adjusted return, unless appropriate risk management measures are put in place.<ref>{{cite journal|title=Should We Build More Large Dams? The Actual Costs of Hydropower Megaproject Development|journal=Energy Policy|volume = 69|date=March 2014|pages=43–56|first1=Atif|last1=Ansar|first2=Bent|last2=Flyvbjerg|first3=Alexander|last3=Budzier|first4=Daniel|last4=Lunn|arxiv=1409.0002|ssrn = 2406852|doi = 10.1016/j.enpol.2013.10.069|s2cid=55722535}}</ref>

====Suitability for industrial applications====
While many hydroelectric projects supply public electricity networks, some are created to serve specific 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]]'s [[Manapouri Power Station]] was constructed to supply electricity to the [[aluminium]] [[smelter]] at [[Comalco|Tiwai Point]].

====Reduced CO<sub>2</sub> emissions====
Since hydroelectric dams do not use fuel, power generation does not produce [[carbon dioxide]]. While carbon dioxide is initially produced during construction of the project, and some methane is given off annually by reservoirs, hydro has one of the lowest [[Life-cycle greenhouse-gas emissions of energy sources|lifecycle greenhouse gas emissions]] for electricity generation.<ref>{{cite web |url=http://hydropower-assets.s3.eu-west-2.amazonaws.com/publications-docs/iha_2018_hydropower_status_report_4.pdf |title=2018 Hydropower Status Report: Sector Trends and Insights |publisher=[[International Hydropower Association]] |date=2018 |access-date=19 March 2022 |page=16}}</ref> The low [[greenhouse gas]] impact of hydroelectricity is found especially in [[temperate climate]]s. Greater greenhouse gas emission impacts are found in the tropical regions because the reservoirs of power stations in tropical regions produce a larger amount of [[methane]] than those in temperate areas.<ref>{{cite journal|title=Climate science: Renewable but not carbon-free|first=Bernhard|last=Wehrli|date=1 September 2011|journal=Nature Geoscience|volume=4|issue=9|pages=585–586|doi=10.1038/ngeo1226|bibcode=2011NatGe...4..585W}}</ref>

Like other non-fossil fuel sources, hydropower also has no emissions of sulfur dioxide, nitrogen oxides, or other particulates.

====Other uses of the reservoir====
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. 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> Managing dams which are also used for other purposes, such as [[irrigation]], is complicated.<ref name=":4" />

===Disadvantages===
{{See also|Renewable energy debate#Disadvantages of hydroelectricity}}In 2021 the IEA called for "robust sustainability standards for all hydropower development with streamlined rules and regulations".<ref name=":4" />

====Ecosystem damage and loss of land====
[[File:MeroweDam01.jpg|thumb|[[Merowe Dam]] in [[Sudan]]. Hydroelectric power stations that use [[dam]]s submerge large areas of land due to the requirement of a [[reservoir]]. These changes to land color or [[albedo]], alongside certain projects that concurrently submerge rainforests, can in these specific cases result in the global warming impact, or equivalent [[Life-cycle greenhouse-gas emissions of energy sources|life-cycle greenhouse gases]] of hydroelectricity projects, to potentially exceed that of coal power stations.]]

Large reservoirs associated with traditional hydroelectric power stations result in submersion of extensive areas upstream of the dams, sometimes destroying biologically rich and productive lowland and riverine valley forests, marshland and grasslands. 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/> The loss of land is often exacerbated by [[habitat fragmentation]] of surrounding areas caused by the reservoir.<ref name=":0">{{cite journal|last=Robbins|first=Paul|title=Hydropower|journal=Encyclopedia of Environment and Society|year=2007|volume=3}}</ref>

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|access-date=2010-07-16|archive-date=2010-10-01|archive-url=https://web.archive.org/web/20101001001803/http://www.internationalrivers.org/en/node/1476|url-status=dead}}</ref> The turbines also will kill large portions of the fauna passing through, for instance 70% of the eel passing a turbine will perish immediately.<ref>{{Cite web|url=https://www.researchgate.net/publication/263678051|title=Loss of European silver eel passing a hydropower station &#124; Request PDF}}</ref><ref>{{cite web | url=https://phys.org/news/2022-01-fish-dies-hydroelectric-turbines.html | title=One in five fish dies from passing hydroelectric turbines }}</ref><ref>{{cite web | url=https://www.newsroom.co.nz/another-nail-in-the-coffin-for-endangered-eels | title=Another nail in the coffin for endangered eels | date=26 August 2019 }}</ref> Since turbine gates are often opened intermittently, rapid or even daily fluctuations in river flow are observed.<ref>{{Cite journal |last1=Glowa |first1=Sarah E. |last2=Kneale |first2=Andrea J. |last3=Watkinson |first3=Douglas A. |last4=Ghamry |first4=Haitham K. |last5=Enders |first5=Eva C. |last6=Jardine |first6=Timothy D. |date=10 February 2023 |title=Applying a 2D-Hydrodynamic Model to Estimate Fish Stranding Risk Downstream from a Hydropeaking Hydroelectric Station |url=https://onlinelibrary.wiley.com/doi/abs/10.1002/eco.2530 |journal=Ecohydrology |volume=E2530|doi=10.1002/eco.2530 |s2cid=256818410 |doi-access=free }}</ref>

====Drought and water loss by evaporation====
Drought and seasonal changes in rainfall can severely limit hydropower.<ref name=":4" /> Water may also be lost by evaporation.<ref>John Macknick and others, [http://www.nrel.gov/docs/fy11osti/50900.pdf A Review of Operational Water Consumption and Withdrawal Factors for Electricity Generating Technologies], National Renewable Energy Laboratory, Technical Report NREL/TP-6A20-50900.</ref>

====Siltation and flow shortage====
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|url-status=dead|archive-url=https://web.archive.org/web/20090902184753/http://www.ijee.dit.ie/articles/Vol14-4/ijee1012.pdf|archive-date=2009-09-02}}</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>

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] {{webarchive |url=https://web.archive.org/web/20120920024704/http://www.odi.org.uk/resources/details.asp?id=5792&title=climate-change-disasters-electricity-generation |date=September 20, 2012 }}. 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 heavy 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/>

====Methane emissions (from reservoirs)====
[[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]]}}.]]

{{See also|Environmental impacts of reservoirs}}

Lower positive impacts are found in the tropical regions. In lowland [[rainforest]] areas, where inundation of a part of the forest is necessary, it has been noted that the reservoirs of power plants produce substantial amounts of [[methane]].<ref>[https://www.newscientist.com/article/mg24332480-200-deliberate-drowning-of-brazils-rainforest-is-worsening-climate-change/ "Deliberate drowning of Brazil's rainforest is worsening climate change"], Daniel Grossman 18 September 2019, ''[[New Scientist]]''; retrieved 30 September 2020</ref> 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|url-status=dead|archive-url=https://web.archive.org/web/20130821120709/http://www.dams.org/report/|archive-date=2013-08-21}}</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=https://www.newscientist.com/article/dn7046-hydroelectric-powers-dirty-secret-revealed/|title=Hydroelectric power's dirty secret revealed|date=24 February 2005|website=NewScientist.com|first=Duncan|last=Graham-Rowe}}</ref>

In [[Boreal forest|boreal]] reservoirs of Canada and Northern Europe, however, [[Greenhouse gas#Sources|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>

====Relocation====
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&nbsp;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|access-date=2008-09-03|archive-date=2008-09-13|archive-url=https://web.archive.org/web/20080913152808/http://internationalrivers.org/en/way-forward/world-commission-dams/world-commission-dams-framework-brief-introduction|url-status=dead}}</ref>

====Failure risks====
{{See also|Dam failure|List of hydroelectric power station failures}}

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.

During Typhoon Nina in 1975 [[Banqiao Dam]] in Southern China failed when more than a year's worth of rain fell within 24 hours (see [[1975 Banqiao Dam failure]]). The resulting flood resulted in the deaths of 26,000 people, and another 145,000 from epidemics. Millions were left homeless.

The creation of a dam in a geologically inappropriate location may cause disasters such as 1963 disaster at [[Vajont Dam]] in Italy, where almost 2,000 people died.<ref name=":1">References may be found in the list of [[Dam failure]]s.</ref>

The [[Malpasset Dam]] failure in [[Fréjus]] on the [[French Riviera]] (Côte d'Azur), southern France, collapsed on December 2, 1959, killing 423 people in the resulting flood.<ref>{{cite web|url=http://ecolo.org/documents/documents_in_french/malpasset/malpasset.htm|title=La catastrophe de Malpasset en 1959| first=Frank|last=Bruel|access-date=2 September 2015}}</ref>

Smaller dams and [[micro hydro]] facilities create less risk, but can form continuing hazards even after being decommissioned. For example, the small earthen embankment [[Kelly Barnes Dam]] failed in 1977, twenty years after its power station was decommissioned, causing 39 deaths.<ref name=":2">[http://ga.water.usgs.gov/news/historical-toccoa/ Toccoa Flood] USGS Historical Site, retrieved 02sep2009</ref>

===Comparison and interactions with other methods of power generation===
{{Update|part=section|date=January 2022|reason=solar panels on reservoirs, also Tasmania link}}
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. In 2021 the IEA said that government [[energy policy]] should "price in the value of the multiple public benefits provided by hydropower plants".<ref name=":4" />

====Nuclear power====
[[Nuclear power]] is relatively inflexible; although it can reduce its output reasonably quickly. Since the cost of nuclear power is dominated by its high infrastructure costs, the cost per unit energy goes up significantly with low production. Because of this, nuclear power is mostly used for [[baseload]]. By way of contrast, hydroelectricity can supply peak power at much lower cost. Hydroelectricity is thus often used to complement nuclear or other sources for [[load following]]. Country examples where they are paired in a close to 50/50 share include [[Electricity sector in Switzerland|the electric grid in Switzerland]], the [[Electricity sector in Sweden]] and to a lesser extent, [[Energy in Ukraine#Electricity|Ukraine]] and the [[Electricity sector in Finland]].

====Wind power====
[[Wind power]] goes through predictable [[Variable renewable energy|variation]] by season, but is [[Intermittent energy source|intermittent]] on a daily basis. Maximum wind generation has little relationship to peak daily electricity consumption, the wind may peak at night when power is not needed or be still during the day when electrical demand is highest. Occasionally weather patterns can result in low wind for days or weeks at a time, a hydroelectric reservoir capable of storing weeks of output is useful to balance generation on the grid. Peak wind power can be offset by minimum hydropower and minimum wind can be offset with maximum hydropower. In this way the easily regulated character of hydroelectricity is used to compensate for the intermittent nature of wind power. Conversely, in some cases wind power can be used to spare water for later use in dry seasons.

An example of this is [[Electricity sector in Norway|Norway's trading]] with Sweden, Denmark, the Netherlands, Germany and the UK.<ref>{{cite web|url=https://www.sintef.no/en/latest-news/norway-is-europes-cheapest-battery/|title=Norway is Europe's cheapest "battery"|website= SINTEF.no|date=18 December 2014}}</ref><ref>{{Cite web|date=2021-05-28|title=Germany and Norway commission NordLink power cable|url=https://www.power-technology.com/news/germany-norway-nordlink/|access-date=2022-01-29|website=Power Technology|language=en-US}}</ref> Norway is 98% hydropower, while its flatland neighbors have wind power. In areas that do not have hydropower, [[pumped storage]] serves a similar role, but at a much higher cost and 20% lower efficiency.{{Citation needed|date=January 2022}}

== Hydro power by country ==

[[File:Share-electricity-hydro.svg |thumb|upright=1.5| Share of electricity production from hydropower, 2022<ref>{{cite web |title=Share of electricity production from hydropower |url=https://ourworldindata.org/grapher/share-electricity-hydro |website=Our World in Data |access-date=15 August 2023}}</ref>]]
[[File:World hydro generation yearly.png |thumb|upright=1.5| Yearly hydro generation by continent<ref name="ember"/>]]
[[File:World hydro generation 2021.png |thumb|upright=1.5| Hydro generation by country, 2021<ref name="ember"/>]]

{{See also|List of countries by renewable electricity production|Cost of electricity by source}}
{{See also|Category:Hydroelectricity by country}}

In 2022 hydro generated 4,289 TWh, 15% of total electricity and half of renewables. Of the world total, [[China]] (30%) produced the most, followed by [[Brazil]] (10%), [[Canada]] (9.2%), the [[United States]] (5.8%) and [[Russia]] (4.6%).

Paraguay produces nearly all of its electricity from hydro and exports far more than it uses.<ref>{{cite web |url = https://dialogochino.net/en/climate-energy/54953-paraguay-electricity-exporter-power-outages/ |title = Paraguay: a significant electricity exporter, but citizens suffer outages |date = 14 Jun 2022 |website = Dialogo China |access-date = 30 Dec 2023}}</ref> Large plants tend to be built by governments, so most capacity (70%) is publicly owned, even though most plants (nearly 70%) are owned and operated by the private sector, as of 2021.<ref name=":4" />

The following table lists these data for each country:

* total generation from hydro in [[kilowatt-hour|terawatt-hours]],
* percent of that country's generation that was [[hydro power|hydro]],
* total hydro capacity in [[watt|gigawatts]],
* percent growth in hydro capacity, and
* the hydro [[capacity factor]] for that year.

Data are sourced from [[Ember (non-profit organisation)|Ember]] and refer to the year 2022 unless otherwise specified.<ref name="ember">{{cite web |url = https://ember-climate.org/data-catalogue/yearly-electricity-data/ |title = Yearly electricity data |date = 6 Dec 2023 |website = ember-climate.org |access-date = 23 Dec 2023}}</ref> Only includes countries with more than 1 TWh of generation. Links for each location go to the relevant hydro power page, when available.

{{sticky header}}{{table alignment}}{{static row numbers}}{{sort under}}
{| class="sortable wikitable sticky-header static-row-numbers sort-under col1left" {{right}}
|-
! Country
! {{abbr|Gen<br/>(TWh)|Generation (Terrawatt-hours)}}
! {{abbr|%<br/>gen.|Percent of generation from hydro power}}
! {{abbr|Cap.<br/>(GW)|Capacity (Gigawatts)}}
! {{abbr|% cap.<br/>growth|Increase in hydro capacity}}
! {{abbr|Cap.<br/>fac.|Capacity factor}}
|- class="static-row-numbers-norank"
| {{noflag|'''World'''}} || 4288.59 || 15.0 || 1255.45 || 1.7 || 39%
|-
| {{flagg|uspef|pref=Hydroelectricity in|China}} || 1303.13 || 14.7 || 367.71 || 3.7 || 40%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Brazil}} || 428.06 || 62.9 || 109.81 || 0.4 || 44%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Canada}} || 392.51 || 61.5 || 83.55 || 1.0 || 54%
|-
| {{flagg|uspef|pref=Hydroelectricity in|United States}} || 248.76 || 5.8 || 83.85 || 0.1 || 34%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Russia}} || 197.41 || 17.6 || 51.40 || 0.0 || 44%
|-
| {{flagg|uspef|pref=Hydroelectricity in|India}} || 174.92 || 9.4 || 47.22 || 0.9 || 42%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Norway}} || 134.86 || 88.3 || 34.12 || 0.2 || 45%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Vietnam}} || 95.96 || 36.9 || 21.86 || 1.3 || 50%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Japan}} || 74.88 || 7.2 || 28.20 || 0.3 || 30%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Sweden}} || 69.38 || 40.3 || 16.41 || 0.0 || 48%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Turkey}} || 67.09 || 20.6 || 31.57 || 0.3 || 24%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Colombia}} || 62.01 || 73.4 || 12.56 || 5.0 || 56%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Venezuela}} (2021) || 61.00 || 64.4 || 16.83 || 0.0 || 41%
|-
| {{flagg|uspef|pref=Hydroelectricity in|France}} || 46.29 || 9.8 || 24.56 || 0.0 || 22%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Paraguay}} (2021) || 39.89 || 99.7 || 8.81 || 0.0 || 52%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Pakistan}} || 36.41 || 23.9 || 10.83 || 7.9 || 38%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Austria}} || 35.54 || 53.9 || 14.97 || 1.5 || 27%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Mexico}} || 35.30 || 10.1 || 13.30 || 0.0 || 30%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Italy}} || 30.77 || 10.8 || 18.84 || 0.2 || 19%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Malaysia}} || 30.72 || 17.0 || 6.21 || 0.0 || 56%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Switzerland}} || 30.48 || 49.0 || 15.07 || 0.1 || 23%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Peru}} || 29.70 || 49.3 || 5.50 || 0.0 || 62%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Laos}} (2021) || 28.51 || 71.3 || 8.79 || 9.5 || 37%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Indonesia}} || 27.30 || 8.2 || 6.69 || 1.4 || 47%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Argentina}} || 26.15 || 18.2 || 10.39 || 0.1 || 29%
|-
| {{flagg|uspef|pref=Hydroelectricity in|New Zealand}} || 25.92 || 58.8 || 5.44 || 0.0 || 54%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Ecuador}} || 24.63 || 74.4 || 5.19 || 1.8 || 54%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Chile}} || 20.27 || 24.4 || 7.29 || 7.1 || 32%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Spain}} || 18.79 || 6.6 || 16.80 || 0.0 || 13%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Tajikistan}} (2021) || 18.00 || 91.2 || 5.27 || 0.0 || 39%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Australia}} || 17.12 || 6.3 || 7.71 || 0.0 || 25%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Germany}} || 17.06 || 3.0 || 5.54 || 0.9 || 35%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Zambia}} (2021) || 16.07 || 90.7 || 2.71 || 12.9 || 68%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Mozambique}} (2021) || 16.00 || 80.4 || 2.19 || 0.0 || 83%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Egypt}} || 14.07 || 6.8 || 2.83 || 0.0 || 57%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Ethiopia}} (2021) || 14.00 || 95.3 || 4.07 || 0.0 || 39%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Romania}} || 14.00 || 25.2 || 6.57 || 0.0 || 24%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Finland}} || 13.74 || 18.9 || 3.17 || 0.0 || 49%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Iceland}} (2021) || 13.57 || 70.5 || 2.11 || 0.0 || 73%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Kyrgyzstan}} (2021) || 13.00 || 89.9 || 2.78 || -24.3 || 53%
|-
| {{flagg|uspef|pref=Hydroelectricity in|North Korea}} (2021) || 12.00 || 83.0 || 4.86 || 0.0 || 28%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Angola}} (2021) || 11.50 || 70.0 || 3.73 || 0.0 || 35%
|-
| {{flagg|uspef|pref=Hydroelectricity in|DR Congo}} (2021) || 11.00 || 99.6 || 2.72 || 0.0 || 46%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Georgia}} || 10.77 || 75.6 || 3.08 || 3.7 || 40%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Ukraine}} || 10.53 || 9.2 || 4.82 || 0.0 || 25%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Sudan}} (2021) || 10.00 || 60.3 || 1.48 || 0.0 || 77%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Costa Rica}} || 9.30 || 73.6 || 2.33 || -2.1 || 46%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Kazakhstan}} || 9.10 || 8.1 || 2.81 || 0.0 || 37%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Bhutan}} (2021) || 9.00 || 100.0 || 2.33 || 0.0 || 44%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Myanmar}} (2021) || 9.00 || 40.2 || 3.30 || 0.0 || 31%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Albania}} (2021) || 8.89 || 99.2 || 2.51 || 5.0 || 40%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Philippines}} || 8.80 || 7.8 || 3.04 || -0.3 || 33%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Nigeria}} || 8.76 || 27.3 || 2.11 || 0.0 || 47%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Serbia}} || 8.66 || 24.6 || 2.48 || 0.4 || 40%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Portugal}} || 7.59 || 16.2 || 7.59 || 4.7 || 11%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Iran}} || 7.45 || 2.1 || 11.50 || 3.1 || 7%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Ghana}} (2021) || 7.21 || 34.5 || 1.58 || 0.0 || 52%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Panama}} (2021) || 7.20 || 64.3 || 1.81 || 0.0 || 45%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Thailand}} || 6.73 || 3.5 || 3.11 || 0.0 || 25%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Nepal}} (2021) || 6.00 || 98.0 || 1.99 || 53.1 || 34%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Guatemala}} (2021) || 5.92 || 41.0 || 1.57 || -0.6 || 43%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Taiwan}} || 5.83 || 2.1 || 2.09 || 0.0 || 32%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Uruguay}} || 5.61 || 35.7 || 1.54 || 0.0 || 42%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Croatia}} || 5.35 || 37.9 || 2.20 || 0.0 || 28%
|-
| {{flagg|uspef|pref=Hydroelectricity in|United Kingdom}} || 5.32 || 1.6 || 2.19 || 0.0 || 28%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Cameroon}} (2021) || 5.00 || 62.1 || 0.81 || 0.0 || 70%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Sri Lanka}} (2021) || 5.00 || 30.6 || 1.80 || 0.0 || 32%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Uzbekistan}} (2021) || 5.00 || 8.5 || 2.05 || 1.5 || 28%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Bosnia and Herzegovina}} || 4.97 || 30.0 || 1.84 || 0.0 || 31%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Iraq}} (2021) || 4.90 || 5.0 || 1.56 || 0.0 || 36%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Greece}} || 4.73 || 9.0 || 3.42 || 0.0 || 16%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Uganda}} (2021) || 4.00 || 90.9 || 1.01 || 0.0 || 45%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Zimbabwe}} (2021) || 4.00 || 49.8 || 1.08 || 0.0 || 42%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Cambodia}} (2021) || 4.00 || 46.0 || 1.33 || 0.0 || 34%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Bulgaria}} || 3.70 || 7.3 || 2.51 || 0.0 || 17%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Slovakia}} || 3.70 || 13.8 || 1.62 || 0.0 || 26%
|-
| {{flagg|uspef|pref=Hydroelectricity in|South Korea}} || 3.55 || 0.6 || 1.81 || -1.6 || 22%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Kenya}} || 3.34 || 27.0 || 0.86 || 1.2 || 44%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Cote d'Ivoire}} (2021) || 3.30 || 30.1 || 0.88 || 0.0 || 43%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Slovenia}} || 3.19 || 24.0 || 1.17 || 0.0 || 31%
|-
| {{flagg|uspef|pref=Hydroelectricity in|South Africa}} || 3.02 || 1.4 || 0.75 || 0.0 || 46%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Tanzania}} (2021) || 3.00 || 36.7 || 0.60 || 1.7 || 57%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Bolivia}} || 2.88 || 25.6 || 0.80 || 0.0 || 41%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Latvia}} || 2.77 || 54.6 || 1.61 || 1.3 || 20%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Honduras}} (2021) || 2.70 || 22.5 || 0.85 || 1.2 || 36%
|-
| {{flagg|uspef|pref=Hydroelectricity in|El Salvador}} || 2.41 || 31.6 || 0.57 || 0.0 || 48%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Armenia}} (2021) || 2.20 || 30.1 || 1.35 || 0.0 || 19%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Poland}} || 2.06 || 1.2 || 0.98 || 1.0 || 24%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Czechia}} || 2.02 || 2.4 || 1.11 || 0.0 || 21%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Guinea}} (2021) || 2.00 || 71.9 || 0.81 || 37.3 || 28%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Montenegro}} || 1.45 || 43.8 || 0.70 || 0.0 || 24%
|-
| {{flagg|uspef|pref=Hydroelectricity in|North Macedonia}} || 1.34 || 23.4 || 0.69 || 0.0 || 22%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Azerbaijan}} (2021) || 1.28 || 4.9 || 1.16 || 0.9 || 13%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Morocco}} (2021) || 1.21 || 2.9 || 1.31 || 0.0 || 11%
|-
| {{flagg|uspef|pref=Hydroelectricity in|Namibia}} (2021) || 1.10 || 70.1 || 0.35 || 0.0 || 36%
|}

==Economics==
{{expand section|date=January 2022}}
The [[weighted average cost of capital]] is a major factor.<ref name=":4" />

==See also==
{{portal|Renewable energy|Energy|Water}}
{{cols|colwidth=26em}}
* [[Energy transition]]
* [[Hydraulic engineering]]
* [[International Hydropower Association]]
* [[International Rivers]]
* [[List of energy storage power plants]]
* [[List of hydroelectric power station failures]]
* [[List of largest power stations]]
* [[List of renewable energy topics by country and territory]]
* [[Lists of hydroelectric power stations]]
* [[Marine current power]] – electricity from sea currents
* [[National Hydropower Association]] (US)
{{colend}}

==References==
{{reflist}}

==External links==
{{Commons category|Hydroelectricity}}
*{{curlie|Science/Technology/Energy/Renewable/Hydro/}}
*[http://www.hydroreform.org/ Hydropower Reform Coalition]
*[http://www.dameffects.org/ Interactive demonstration on the effects of dams on rivers] {{Webarchive|url=https://web.archive.org/web/20190725155321/https://www.dameffects.org/ |date=2019-07-25 }}
*[https://web.archive.org/web/20110501225851/http://www.esha.be/ European Small Hydropower Association]
*[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] {{Webarchive|url=https://web.archive.org/web/20150427003621/http://tc4.iec.ch/index-tc4.html |date=2015-04-27 }} 

{{Electricity generation}}
{{Hydropower}}
{{Energy country lists}}
{{Climate change}}
{{Sustainability}}

{{Authority control}}

[[Category:Bright green environmentalism]]
[[Category:Hydroelectricity| ]]
[[Category:Landscape]]
[[Category:Sustainable technologies]]