Editing Hydropower (section)

== History ==
===Ancient history===
[[File:水击面罗.jpg|thumb|A water piston from the ''Nongshu'' by [[Wang Zhen (inventor)|Wang Zhen]] (fl. 1290–1333)]]
[[File:SaintAnthonyFalls.jpg|thumb|[[Saint Anthony Falls]], [[United States]]; hydropower was used here to mill flour.]]
[[File: WATER-POWERED ORE MILL, TAKEN FROM SOUTH - Liberty Historic District, Water Powered Ore Mill, Route 2, Cle Elum, Liberty, Kittitas County, WA HABS WASH,19-LIB,1W-1.tif|thumb|Directly water-powered ore mill, late nineteenth century]]
Evidence suggests that the fundamentals of hydropower date to [[Ancient Greece|ancient Greek civilization]].<ref name="Munoz-Hernandez-2013">{{cite book |last1=Munoz-Hernandez |first1=German Ardul |url=https://www.springer.com/gp/book/9781447122906 |title=Modelling and Controlling Hydropower Plants |last2=Mansoor |first2=Sa'ad Petrous |last3=Jones |first3=Dewi Ieuan |date=2013 |publisher=Springer London |isbn=978-1-4471-2291-3 |location=London |page= |author-link1= |author-link2= |author-link3=}}</ref> Other evidence indicates that the waterwheel independently emerged in China around the same period.<ref name="Munoz-Hernandez-2013" /> Evidence of [[water wheel]]s and [[watermill]]s date to the [[ancient Near East]] in the 4th century BC.{{sfn|Reynolds|1983|p=14}} Moreover, evidence indicates the use of hydropower using irrigation machines to ancient civilizations such as [[Sumer]] and [[Babylonia]].{{sfn|Breeze|2018|p={{pn|date=March 2025}}}} Studies suggest that the water wheel was the initial form of water power.{{sfn|Breeze|2018|p={{pn|date=March 2025}}}}

In the [[Roman Empire]], water-powered mills were described by [[Vitruvius]] by the first century BC.<ref name="Oleson2">{{cite book |last=Oleson |first=John Peter |title=Greek and Roman mechanical water-lifting devices: the history of a technology |date=1984 |publisher=Springer |isbn=90-277-1693-5 |page=373 |id={{ASIN|9027716935|country=uk}} |author-link=John Peter Oleson |jstor=10.3138/j.ctvcj2t2n }}</ref> The [[Barbegal mill]], located in modern-day France, had 16 water wheels processing up to 28 tons of grain per day.<ref name="Hill-2013" /> Roman waterwheels were also used for sawing marble such as the [[Hierapolis sawmill]] of the late 3rd century AD.<ref>{{cite journal |last1=Greene |first1=Kevin |date=1990 |title=Perspectives on Roman technology |journal=Oxford Journal of Archaeology |volume=9 |issue=2 |pages=209–219 |doi=10.1111/j.1468-0092.1990.tb00223.x }}</ref> Such sawmills had a waterwheel that drove two crank-and-connecting rods to power two saws. It also appears in two 6th century [[Byzantine Empire|Eastern Roman]] [[sawmill]]s excavated at [[Ephesus]] and [[Gerasa]] respectively. The [[Crank (mechanism)|crank]] and connecting rod mechanism of these [[List of Roman watermills|Roman watermills]] converted the rotary motion of the waterwheel into the linear movement of the saw blades.<ref>{{cite book |last=Magnusson |first=Roberta J. |url= |title=Water Technology in the Middle Ages: Cities, Monasteries, and Waterworks after the Roman Empire |date=2002 |publisher=Johns Hopkins University Press |isbn=978-0-8018-6626-5 |location=Baltimore |page= |author-link=}}{{pn|date=March 2025}}</ref> 

Water-powered trip hammers and bellows in China, during the [[Han dynasty]] (202&nbsp;BC – 220&nbsp;AD), were initially thought to be powered by [[Water scoop (hydropower)|water scoops]].{{sfn|Reynolds|1983|pp=26–30}} However, some historians suggested that they were powered by waterwheels. This is since it was theorized that water scoops would not have had the motive force to operate their [[blast furnace]] bellows.<ref>{{cite book |last=Lucas |first=Adam |url= |title=Wind, Water, Work: Ancient and Medieval Milling Technology |date=2006 |publisher=Brill |isbn= |location=Leiden |page=55 |author-link=}}</ref> Many texts describe the Hun waterwheel; some of the earliest ones are the ''[[Jijiupian]]'' dictionary of 40&nbsp;BC, [[Yang Xiong (author)|Yang Xiong]]'s text known as the ''[[Fangyan (book)|Fangyan]]'' of 15&nbsp;BC, as well as ''Xin Lun,'' written by [[Huan Tan]] about 20 AD.<ref name="Needham-1986">{{cite book |last=Needham |first=Joseph |url= |title=Science and Civilisation in China, Volume 4: Physics and Physical Technology, Part 2, Mechanical Engineering |date=1986 |publisher=Cambridge University Press |isbn=0-521-05803-1 |location=Taipei |page=370 |author-link=Joseph Needham}}</ref> It was also during this time that the engineer [[Du Shi]] (c.&nbsp;AD&nbsp;31) applied the power of [[waterwheel]]s to [[piston]]-[[bellows]] in forging cast iron.<ref name="Needham-1986" />

Ancient Indian texts dating back to the 4th century BC refer to the term ''cakkavattaka'' (turning wheel), which commentaries explain as ''arahatta-ghati-yanta'' (machine with wheel-pots attached), however whether this is water or hand powered is disputed by scholars{{sfn|Reynolds|1983|p=14}} On this basis, [[Joseph Needham]] suggested that the machine was a [[noria]]. Terry S. Reynolds, however, argues that the "term used in Indian texts is ambiguous and does not clearly indicate a water-powered device."{{cite quote|date=March 2025}} Thorkild Schiøler argued that it is "more likely that these passages refer to some type of tread- or hand-operated water-lifting device, instead of a water-powered water-lifting wheel."{{cite quote|date=March 2025}}

India received Roman water mills and baths in the early 4th century AD when a certain according to Greek sources.<ref>{{harvnb|Wikander|2000|p=400}}: {{blockquote|This is also the period when water-mills started to spread outside the former Empire. According to [[Cedrenus]] (Historiarum compendium), a certain Metrodoros who went to India in c. A.D. 325 "constructed water-mills and baths, unknown among them [the Brahmans] till then".}}</ref> Dams, spillways, reservoirs, channels, and water balance would develop in India during the [[Maurya Empire|Mauryan]], [[Gupta Empire|Gupta]] and [[Chola Empire|Chola]] empires.<ref name="Hill2008">{{cite book |author=Christopher V. Hill |url=https://books.google.com/books?id=f9D4Ob1YcJgC&pg=PA33 |title=South Asia: An Environmental History |publisher=ABC-CLIO |year=2008 |isbn=978-1-85109-925-2 |pages=33–}}</ref><ref>{{cite book |doi=10.1007/978-3-030-87067-6_18 |chapter=Evolution of Water Management Practices in India |title=Riverine Systems |date=2022 |last1=Jain |first1=Sharad |last2=Sharma |first2=Aisha |last3=Mujumdar |first3=P. P. |pages=325–349 |isbn=978-3-030-87066-9 }}</ref><ref>{{cite journal |last1=Singh |first1=Pushpendra Kumar |last2=Dey |first2=Pankaj |last3=Jain |first3=Sharad Kumar |last4=Mujumdar |first4=Pradeep P. |title=Hydrology and water resources management in ancient India |journal=Hydrology and Earth System Sciences |date=5 October 2020 |volume=24 |issue=10 |pages=4691–4707 |doi=10.5194/hess-24-4691-2020 |doi-access=free |bibcode=2020HESS...24.4691S }}</ref>

Another example of the early use of hydropower is seen in [[hushing]], a historic method of mining that uses flood or torrent of water to reveal mineral veins. The method was first used at the [[Dolaucothi Gold Mines]] in [[Wales]] from 75 AD onwards. This method was further developed in Spain in mines such as [[Las Médulas]]. Hushing was also widely used in [[Great Britain|Britain]] in the [[Middle Ages|Medieval]] and later periods to extract [[lead]] and [[tin]] ores. It later evolved into [[hydraulic mining]] when used during the [[California Gold Rush]] in the 19th century.<ref>{{cite journal |last1=Nakamura |first1=Tyler K. |last2=Singer |first2=Michael Bliss |last3=Gabet |first3=Emmanuel J. |date=2018 |title=Remains of the 19th Century: Deep storage of contaminated hydraulic mining sediment along the Lower Yuba River, California |journal=Elem Sci Anth |volume=6 |issue=1 |pages=70 |doi=10.1525/elementa.333 |doi-access=free |bibcode=2018EleSA...6...70N }}</ref>

The [[Islamic Empire]] spanned a large region, mainly in Asia and Africa, along with other surrounding areas.<ref>{{cite book |last=Hoyland |first=Robert G. |url= |title=In God's Path: The Arab Conquests and the Creation of an Islamic Empire |date=2015 |publisher=Oxford University Press |isbn=978-0-19-991636-8 |location=Oxford |page= |author-link=Robert G. Hoyland}}</ref> During the [[Islamic Golden Age]] and the [[Arab Agricultural Revolution]] (8th–13th centuries), hydropower was widely used and developed. Early uses of [[tidal power]] emerged along with large hydraulic [[factory]] complexes.<ref name="al-Hassan-1976">{{cite book |last1=al-Hassan |first1=Ahmad Y. |date=1976 |title=Taqī-al-Dīn and Arabic Mechanical Engineering. With the Sublime Methods of Spiritual Machines. An Arabic Manuscript of the Sixteenth Century |publisher=Institute for the History of Arabic Science, University of Aleppo |pages=34–35 |oclc=7902681 }}</ref> A wide range of water-powered industrial mills were used in the region including [[fulling]] mills, [[gristmill]]s, [[paper mill]]s, [[Rice huller|hullers]], [[sawmill]]s, [[ship mill]]s, [[stamp mill]]s, [[steel mill]]s, [[Sugar refinery|sugar mills]], and [[tide mill]]s. By the 11th century, every province throughout the Islamic Empire had these industrial mills in operation, from [[Al-Andalus]] and [[North Africa]] to the [[Middle East]] and [[Central Asia]].<ref name="Lucas2">{{cite journal |last1=Lucas |first1=Adam Robert |date=2005 |title=Industrial Milling in the Ancient and Medieval Worlds: A Survey of the Evidence for an Industrial Revolution in Medieval Europe |journal=Technology and Culture |volume=46 |issue=1 |pages=1–30 |doi=10.1353/tech.2005.0026 |jstor=40060793 }}</ref>{{rp|10}} Muslim engineers also used [[water turbine]]s while employing [[gear]]s in watermills and water-raising machines. They also pioneered the use of [[dams]] as a source of water power, used to provide additional power to watermills and water-raising machines.<ref name="Hassan2">{{cite web |last=al-Hassan |first=Ahmad Y. |date= |title=Transfer Of Islamic Technology To The West, Part II: Transmission Of Islamic Engineering |url=http://www.history-science-technology.com/Articles/articles%2071.htm |archive-url=https://web.archive.org/web/20080218171021/http://www.history-science-technology.com/Articles/articles%2071.htm |archive-date=18 February 2008 |access-date= |website=History of Science and Technology in Islam |publisher= |quote=}}</ref> Islamic irriguation techniques including [[Saqiyah|Persian Wheels]] would be introduced to India, and would be combined with local methods, during the [[Delhi Sultanate]] and the [[Mughal Empire]].<ref>Siddiqui{{full|date=March 2025}}</ref>

Furthermore, in his book, ''The Book of Knowledge of Ingenious Mechanical Devices'', the Muslim mechanical engineer, [[Al-Jazari]] (1136–1206) described designs for 50 devices. Many of these devices were water-powered, including clocks, a device to serve wine, and five devices to lift water from rivers or pools, where three of them are animal-powered and one can be powered by animal or water. Moreover, they included an endless belt with jugs attached, a cow-powered [[shadoof]] (a crane-like irrigation tool), and a reciprocating device with hinged valves.<ref>{{cite journal |last1=Jones |first1=R V |title=The Book of Knowledge of Ingenious Mechanical Devices |journal=Physics Bulletin |date=October 1974 |volume=25 |issue=10 |pages=474 |doi=10.1088/0031-9112/25/10/040 }}</ref>
[[File:Benoît Fourneyron portrait.jpg|thumb|Benoît Fourneyron, the French engineer who developed the first hydropower turbine]]

===19th century===
In the 19th century, French engineer [[Benoît Fourneyron]] developed the first hydropower turbine. This device was implemented in the commercial plant of [[Niagara Falls]] in 1895 and it is still operating.{{sfn|Breeze|2018|p={{pn|date=March 2025}}}} In the early 20th century, English engineer [[William Armstrong, 1st Baron Armstrong|William Armstrong]] built and operated the first private electrical power station which was located in his house in [[Cragside]] in [[Northumberland]], England.{{sfn|Breeze|2018|p={{pn|date=March 2025}}}} In 1753, the French engineer [[Bernard Forest de Bélidor]] published his book, ''Architecture Hydraulique'', which described vertical-axis and horizontal-axis hydraulic machines.<ref name="doehis">{{cite web |title=History of Hydropower |url=http://www1.eere.energy.gov/windandhydro/hydro_history.html |url-status=dead |archive-url=https://web.archive.org/web/20100126001540/http://www1.eere.energy.gov/windandhydro/hydro_history.html |archive-date=26 January 2010 |publisher=US 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> At the beginning of the Industrial Revolution in Britain, water was the main power source for new inventions such as [[Richard Arkwright]]'s [[water frame]].<ref name="Perkin-1969">{{cite book |last=Perkin |first=Harold James |url= |title=The Origins of Modern English Society, 1780-1880 |date=1969 |publisher=Routledge & Kegan Paul PLC |isbn=978-0-7100-4567-6 |location=London |page= |author-link=Harold Perkin}}</ref> Although water power gave way to steam power in many of the larger mills and factories, it was still used during the 18th and 19th centuries for many smaller operations, such as driving the bellows in small [[blast furnace]]s (e.g. the [[Dyfi Furnace]]) and [[gristmill]]s, such as those built at [[Saint Anthony Falls]], which uses the {{convert|50|ft|m|adj=on}} drop in the [[Mississippi River]].<ref name="River of History">{{cite web |last1=Anfinson |first1=John |title=River of History: A Historic Resources Study of the Mississippi National River and Recreation Area |url=https://www.nps.gov/miss/learn/historyculture/river-of-hisory-chapter-6.htm |website=River Of History |publisher=National Park System |access-date=12 July 2023}}</ref><ref name="Perkin-1969" />

Technological advances moved the open water wheel into an enclosed [[turbine]] or [[Water engine|water motor]]. In 1848, the British-American engineer [[James B. Francis]], head engineer of Lowell's Locks and Canals company, improved on these designs to create a turbine with 90% efficiency.<ref>{{Cite journal |last1=Lewis |first1=B J |last2=Cimbala |last3=Wouden |year=2014 |title=Major historical developments in the design of water wheels and Francis hydroturbines |journal=IOP Conference Series: Earth and Environmental Science |publisher=IOP |volume=22 |issue=1 |pages=5–7 |bibcode=2014E&ES...22a2020L |doi=10.1088/1755-1315/22/1/012020 |doi-access=free}}</ref> He applied scientific principles and testing methods to the problem of turbine design. His mathematical and graphical calculation methods allowed the confident design of high-efficiency turbines to exactly match a site's specific flow conditions. The [[Francis turbine|Francis reaction turbine]] is still in use. In the 1870s, deriving from uses in the California mining industry, [[Lester Allan Pelton]] developed the high-efficiency [[Pelton wheel|Pelton wheel impulse turbine]], which used hydropower from the high head streams characteristic of the [[Sierra Nevada]].{{Citation needed|date=April 2021}}

===20th century===
The modern history of hydropower begins in the 1900s, with large dams built not simply to power neighboring mills or factories<ref>{{Citation | author=Montrie, C. | title=Water Power, Industrial Manufacturing, and Environmental Transformation in 19th-Century New England | url=https://energyhistory.yale.edu/units/water-power-industrial-manufacturing-and-environmental-transformation-19th-century-new-england | access-date=7 May 2022}}</ref> but provide extensive electricity for increasingly distant groups of people. Competition drove much of the global hydroelectric craze: Europe competed amongst itself to electrify first, and the United States' hydroelectric plants in [[Niagara Falls]] and the [[Sierra Nevada]] inspired bigger and bolder creations across the globe.{{sfn|Blackbourn|2006|pp=217–218}} American and USSR financers and hydropower experts also spread the gospel of dams and hydroelectricity across the globe during the [[Cold War]], contributing to projects such as the [[Three Gorges Dam]] and the [[Aswan Dam|Aswan High Dam]].<ref>{{cite book | last=McCully | first = P | date= 2001 | title=Silenced rivers: the ecology and politics of large dams | publisher=Zed Books | isbn=978-1-85649-901-9|pages=18–19}}</ref>   
Feeding desire for large scale electrification with water inherently required large dams across powerful rivers,{{sfn|McCully|2001|p=227}} which impacted public and private interests downstream and in flood zones.{{sfn|Blackbourn|2006|p=222–24}} Inevitably smaller communities and marginalized groups suffered. They were unable to successfully resist companies flooding them out of their homes or blocking traditional [[salmon]] passages.<ref>{{Citation | year=2014 | title=DamNation | publisher=Patagonia Films, Felt Soul Media, Stoecker Ecological}}</ref> The stagnant water created by hydroelectric dams provides breeding ground for pests and [[pathogens]], leading to local [[epidemics]].{{sfn|McCully|2001|p=93}} However, in some cases, a mutual need for hydropower could lead to cooperation between otherwise adversarial nations.<ref>{{cite journal |last1=Frey |first1=Felix |title=A FLUID IRON CURTAIN: Norwegian–Soviet Hydropower Cooperation in the Pasvik Valley, 1955–1965 |journal=Scandinavian Journal of History |date=7 August 2020 |volume=45 |issue=4 |pages=506–526 |doi=10.1080/03468755.2019.1629336 }}</ref>
 
Hydropower technology and attitude began to shift in the second half of the 20th century. While countries had largely abandoned their small hydropower systems by the 1930s, the smaller hydropower plants began to make a comeback in the 1970s, boosted by government subsidies and a push for more independent energy producers.{{sfn|McCully|2001|p=227}} Some politicians who once advocated for large hydropower projects in the first half of the 20th century began to speak out against them, and citizen groups organizing against dam projects increased.<ref>{{cite journal | author=D’Souza, R. | journal=Monthly Review | title=Framing India's Hydraulic Crisis: The Politics of the Modern Large Dam | pages=112–124 | date=7 July 2008 | volume=60 | issue=3 | doi=10.14452/MR-060-03-2008-07_7}}</ref>

In the 1980s and 90s the international anti-dam movement had made finding government or private investors for new large hydropower projects incredibly difficult, and given rise to NGOs devoted to fighting dams.<ref>{{cite journal |last1=Gocking |first1=Roger |title=Ghana's Bui Dam and the Contestation over Hydro Power in Africa |journal=African Studies Review |date=June 2021 |volume=64 |issue=2 |pages=339–362 |doi=10.1017/asr.2020.41 }}</ref> Additionally, while the cost of other energy sources fell, the cost of building new hydroelectric dams increased 4% annually between 1965 and 1990, due both to the increasing costs of construction and to the decrease in high quality building sites.{{sfn|McCully|2001|p=274}} In the 1990s, only 18% of the world's electricity came from hydropower.{{sfn|McCully|2001|p=134}} [[Tidal power]] production also emerged in the 1960s as a burgeoning alternative hydropower system, though still has not taken hold as a strong energy contender.<ref>{{cite journal | author=Charlier, R. H. | journal=Renewable and Sustainable Energy Reviews | title=Forty candles for the Rance River TPP tides provide renewable and sustainable power generation | volume=11 | issue=9 | pages=2032–2057 | date=December 2007 | doi=10.1016/j.rser.2006.03.015| bibcode=2007RSERv..11.2032C }}</ref>

====United States====
Especially at the start of the American hydropower experiment, engineers and politicians began major hydroelectricity projects to solve a problem of 'wasted potential' rather than to power a population that needed the electricity. When the [[Niagara Falls Power Company]] began looking into damming Niagara, the first major hydroelectric project in the United States, in the 1890s they struggled to transport electricity from the falls far enough away to actually reach enough people and justify installation. The project succeeded in large part due to [[Nikola Tesla|Nikola Tesla's]] invention of the [[alternating current motor]].{{sfn|Berton|2010|pp=203–209}}{{sfn|Berton|2010|p=216}} On the other side of the country, [[San Francisco]] engineers, the [[Sierra Club]], and the federal government fought over acceptable use of the [[Hetch Hetchy Valley]]. Despite ostensible protection within a national park, city engineers successfully won the rights to both water and power in the Hetch Hetchy Valley in 1913. After their victory they delivered Hetch Hetchy hydropower and water to San Francisco a decade later and at twice the promised cost, selling power to [[PG&E]] which resold to San Francisco residents at a profit.<ref>{{cite journal | author=Sinclair, B. | journal=Technology and Culture | title=The Battle over Hetch Hetchy: America's Most Controversial Dam and the Birth of Modern Environmentalism (review) | volume=47 | issue=2 | pages=444–445 | publisher=Johns Hopkins University Press | date= 2006 | doi=10.1353/tech.2006.0153 }}</ref><ref>{{Citation | year=2020 | title=Hetch Hetchy| url=https://www.yosemite.com/hetch-hetchy/ | access-date=8 May 2022}}</ref>{{sfn|Blackbourn|2006|p=218}}

The American West, with its mountain rivers and lack of coal, turned to hydropower early and often, especially along the [[Columbia River]] and its tributaries. The [[Bureau of Reclamation]] built the [[Hoover Dam]] in 1931, symbolically linking the job creation and economic growth priorities of the [[New Deal]].<ref>{{Citation | author=Lee, G. | title=The Big Dam Era | url=https://energyhistory.yale.edu/units/big-dam-era | access-date=8 May 2022}}</ref> The federal government quickly followed Hoover with the [[Shasta Dam]] and [[Grand Coulee Dam]]. Power demand in [[Oregon]] did not justify damming the Columbia until [[WWI]] revealed the weaknesses of a coal-based energy economy. The federal government then began prioritizing interconnected power—and lots of it.{{sfn|White|1995|pp=48–58}} Electricity from all three dams poured into war production during [[WWII]].{{sfn|McCully|2001|p=16}}

After the war, the [[Grand Coulee Dam]] and accompanying hydroelectric projects electrified almost all of the rural [[Columbia Plateau|Columbia Basin]], but failed to improve the lives of those living and farming there the way its boosters had promised and also damaged the river ecosystem and migrating salmon populations. In the 1940s as well, the federal government took advantage of the sheer amount of unused power and flowing water from the Grand Coulee to build a [[nuclear power|nuclear]] site placed on the banks of the Columbia. The nuclear site leaked radioactive matter into the river, contaminating the entire area.{{sfn|White|1995|pp=71–72, 85, 89–111}}

Post-WWII Americans, especially engineers from the [[Tennessee Valley Authority]], refocused from simply building domestic dams to promoting hydropower abroad.<ref name="Big Dam Era">{{Citation | author=Lee, G. | title=The Big Dam Era| url=https://energyhistory.yale.edu/units/big-dam-era | access-date=8 May 2022}}</ref><ref name="Hydropolitics, Economy, and the Asw">{{cite journal |id={{ProQuest|742434774}} |last1=Shokr |first1=Ahmad |title=Hydropolitics, Economy, and the Aswan High Dam in Mid-Century Egypt |journal=Arab Studies Journal; Washington |volume=17 |issue=1 |date=Spring 2009 |pages=9–31 }}</ref> While domestic dam building continued well into the 1970s, with the Reclamation Bureau and [[United States Army Corps of Engineers|Army Corps of Engineers]] building more than 150 new dams across the American West,<ref name="Big Dam Era" /> organized opposition to hydroelectric dams sparked up in the 1950s and 60s based on environmental concerns. Environmental movements successfully shut down proposed hydropower dams in [[Dinosaur National Monument]] and the [[Grand Canyon]], and gained more hydropower-fighting tools with 1970s environmental legislation. As nuclear and fossil fuels grew in the 70s and 80s and environmental activists push for river restoration, hydropower gradually faded in American importance.<ref>{{Citation | author=Lee, G. | title=The End of the Big Dam Era | url=https://energyhistory.yale.edu/units/end-big-dam-era | access-date=8 May 2022}}</ref>

====Africa====
	Foreign powers and [[intergovernmental organization|IGOs]] have frequently used hydropower projects in Africa as a tool to interfere in the economic development of African countries, such as the [[World Bank]] with the [[Kariba Dam|Kariba]] and [[Akosombo Dam]]s, and the [[Soviet Union]] with the [[Aswan Dam]].<ref>{{cite journal | author=Gocking, R. | journal=African Studies Review | title=Ghana's Bui Dam and the Contestation over Hydro Power in Africa | volume=64 | issue=2 | pages=339–362 | publisher=Cambridge University Press | date= June 2021 | doi=10.1017/asr.2020.41 }}</ref> The [[Nile River]] especially has borne the consequences of countries both along the Nile and distant foreign actors using the river to expand their economic power or national force. After the British occupation of [[Egypt]] in 1882, the British worked with Egypt to construct the first Aswan Dam,<ref>{{cite book | author=Ross, C. | date= 2017 | title=Ecology and power in the age of empire: Europe and the transformation of the tropical world | publisher=Oxford University Press |pages=37–38| isbn=978-0-19-182990-1}}</ref> which they heightened in 1912 and 1934 to try to hold back the Nile floods. Egyptian engineer [[Adriano Daninos]] developed a plan for the Aswan High Dam, inspired by the Tennessee Valley Authority's multipurpose dam.

When [[Gamal Abdel Nasser]] took power in the 1950s, his government decided to undertake the High Dam project, publicizing it as an economic development project.<ref name="Hydropolitics, Economy, and the Asw"/> After American refusal to help fund the dam, and anti-British sentiment in Egypt and British interests in neighboring [[Sudan]] combined to make the United Kingdom pull out as well, the Soviet Union funded the Aswan High Dam.<ref>{{cite journal |last1=Dougherty |first1=James E. |title=The Aswan Decision in Perspective |journal=Political Science Quarterly |date=1959 |volume=74 |issue=1 |pages=21–45 |doi=10.2307/2145939 |jstor=2145939 }}</ref> Between 1977 and 1990 the dam's turbines generated one third of Egypt's electricity.{{sfn|McNeill|2001|pp=169–170}} The building of the Aswan Dam triggered a dispute between Sudan and Egypt over the sharing of the Nile, especially since the dam flooded part of Sudan and decreased the volume of water available to them. [[Ethiopia]], also located on the Nile, took advantage of the Cold War tensions to request assistance from the United States for their own irrigation and hydropower investments in the 1960s.<ref>{{cite journal |last1=Swain |first1=Ashok |title=Ethiopia, the Sudan, and Egypt: The Nile River Dispute |journal=The Journal of Modern African Studies |date=December 1997 |volume=35 |issue=4 |pages=675–694 |doi=10.1017/S0022278X97002577 }}</ref> While progress stalled due to the [[Ethiopian Revolution|coup d'état of 1974]] and following 17-year-long [[Ethiopian Civil War]] Ethiopia began construction on the [[Grand Ethiopian Renaissance Dam]] in 2011.<ref>{{cite journal |last1=Gebreluel |first1=Goitom |title=Ethiopia's Grand Renaissance Dam: Ending Africa's Oldest Geopolitical Rivalry? |journal=The Washington Quarterly |date=3 April 2014 |volume=37 |issue=2 |pages=25–37 |doi=10.1080/0163660X.2014.926207 }}</ref>

Beyond the Nile, hydroelectric projects cover the rivers and lakes of Africa. The [[Inga dams|Inga powerplant]] on the [[Congo River]] had been discussed since Belgian colonization in the late 19th century, and was successfully built after independence. [[Mobuto Sese Seko|Mobutu's]] government failed to regularly maintain the plants and their capacity declined until the 1995 formation of the [[Southern African Power Pool]] created a multi-national power grid and plant maintenance program.<ref>{{cite journal |last1=Gottschalk |first1=Keith |title=Hydro-politics and hydro-power: the century-long saga of the Inga project |journal=Canadian Journal of African Studies |date=3 May 2016 |volume=50 |issue=2 |pages=279–294 |doi=10.1080/00083968.2016.1222297 }}</ref> States with an abundance of hydropower, such as the [[Democratic Republic of the Congo]] and [[Ghana]], frequently sell excess power to neighboring countries.<ref name = "Tsikudo">{{cite journal |last1=Adovor Tsikudo |first1=Kwame |title=Ghana's Bui Hydropower Dam and Linkage Creation Challenges |journal=Forum for Development Studies |date=2 January 2021 |volume=48 |issue=1 |pages=153–174 |doi=10.1080/08039410.2020.1858953 }}</ref> Foreign actors such as Chinese hydropower companies have proposed a significant amount of new hydropower projects in Africa,<ref>{{cite journal |last1=Gocking |first1=Roger |title=Ghana's Bui Dam and the Contestation over Hydro Power in Africa |journal=African Studies Review |date=June 2021 |volume=64 |issue=2 |pages=339–362 |doi=10.1017/asr.2020.41 }}</ref> and already funded and consulted on many others in countries like [[Mozambique]] and Ghana.<ref name = "Tsikudo" />

Small hydropower also played an important role in early 20th century electrification across Africa. In South Africa, small turbines powered gold mines and the first electric railway in the 1890s, and Zimbabwean farmers installed small hydropower stations in the 1930s. While interest faded as national grids improved in the second half of the century, 21st century national governments in countries including South Africa and Mozambique, as well as NGOs serving countries like Zimbabwe, have begun re-exploring small-scale hydropower to diversify power sources and improve rural electrification.<ref>{{cite journal |last1=Klunne |first1=Qim Jonker |title=Small hydropower in Southern Africa – an overview of five countries in the region |journal=Journal of Energy in Southern Africa |date=August 2013 |volume=24 |issue=3 |pages=14–25 |doi=10.17159/2413-3051/2013/v24i3a3138 |doi-broken-date=10 March 2025 |id={{CORE output|231111067}} |url=https://journals.assaf.org.za/index.php/jesa/article/view/3138 }}</ref>

====Europe====
In the early 20th century, two major factors motivated the expansion of hydropower in Europe: in the northern countries of [[Norway]] and [[Sweden]], high rainfall and mountains proved exceptional resources for abundant hydropower, and in the south, coal shortages pushed governments and utility companies to seek alternative power sources.<ref>{{cite journal |last1=Bartolomé Rodríguez |first1=Isabel |title=¿Fue el sector eléctrico un gran beneficiario de «la política hidráulica» anterior a la Guerra Civil? (1911-1936) |trans-title=Was the electricity sector a major beneficiary of the 'hydraulic policy' prior to the Civil War? (1911–1936) |language=es |journal=Hispania |date=30 December 2011 |volume=71 |issue=239 |pages=789–818 |doi=10.3989/hispania.2011.v71.i239.360 |doi-access=free }}</ref>

Early on, [[Switzerland]] dammed the Alpine rivers and the [[Rhine|Swiss Rhine]], creating, along with [[Italy]] and [[Scandinavia]], a Southern Europe hydropower race.{{sfn|Blackbourn|2006|p=217}} In Italy's [[Po Valley]], the main 20th-century transition was not the creation of hydropower but the transition from mechanical to electrical hydropower. 12,000 watermills churned in the Po watershed in the 1890s, but the first commercial hydroelectric plant, completed in 1898, signaled the end of the mechanical reign.<ref name = "Parrinello">{{cite journal |last1=Parrinello |first1=Giacomo |title=Systems of Power: A Spatial Envirotechnical Approach to Water Power and Industrialization in the Po Valley of Italy, ca.1880–1970 |journal=Technology and Culture |date=2018 |volume=59 |issue=3 |pages=652–688 |doi=10.1353/tech.2018.0062 |pmid=30245498 }}</ref> These new large plants moved power away from rural mountainous areas to urban centers in the lower plain. Italy prioritized early near-nationwide electrification, almost entirely from hydropower, which powered its rise as a dominant European and imperial force. However, they failed to reach any conclusive standard for determining water rights before WWI.{{sfn|McNeill|2001|pp=174–175}}<ref name = "Parrinello"/>

Modern German hydropower dam construction was built on a history of small dams powering mines and mills in the 15th century. Some parts of the German industry relied more on waterwheels than steam until the 1870s.{{sfn|Blackbourn|2006|p=198–207}} The German government did not set out building large dams such as the prewar [[Urft Dam|Urft]], [[Möhne Reservoir|Mohne]], and [[Edersee Dam|Eder]] dams to expand hydropower: they mostly wanted to reduce flooding and improve navigation.{{sfn|Blackbourn|2006|p=212–213}} However, hydropower quickly emerged as a bonus for all these dams, especially in the coal-poor south. [[Bavaria]] even achieved a statewide power grid by damming the [[Walchensee]] in 1924, inspired in part by loss of coal reserves after WWI.<ref>{{cite journal |last1=Landry |first1=Marc |title=Environmental Consequences of the Peace: The Great War, Dammed Lakes, and Hydraulic History in the Eastern Alps |journal=Environmental History |date=July 2015 |volume=20 |issue=3 |pages=422–448 |doi=10.1093/envhis/emv053 }}</ref>

Hydropower became a symbol of regional pride and distaste for northern 'coal barons', although the north also held strong enthusiasm for hydropower.{{sfn|Blackbourn|2006|p=219}} Dam building rapidly increased after WWII, aiming to increase hydropower.{{sfn|Blackbourn|2006|p=327}} However, conflict accompanied the dam building and spread of hydropower: agrarian interests suffered from decreased irrigation, small mills lost water flow, and different interest groups fought over where dams should be located, controlling who benefited and whose homes they drowned.{{sfn|Blackbourn|2006|p=222–236}}