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| [[Category:Done 2015-09-05]] | | #REDIRECT[[Hydropower]] |
| [[File:Ingur_Hydroelectric_Power_Station.jpg|360px|thumb|right|Figure 1. A hydroelectric dam where hydroelectricity is generated.<ref>Wikimedia Commons. (August 31, 2015). ''Ingur Hydroelectric Facility'' [Online]. Available: https://commons.wikimedia.org/wiki/File:Ingur_Hydroelectric_Power_Station.jpg</ref>]] | | [[Category:Done 2018-06-01]] |
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| <onlyinclude>'''Hydroelectricity''' is the [[electricity]] that is generated by converting the [[kinetic energy|kinetic]] and [[potential energy]] of flowing [[water]] into [[electrical energy]].</onlyinclude> Today, hydroelectricity supplies the world with about 16% of total electric [[power]] generation, while values in the earlier twentieth century were much higher - making up as much as 40% of the United States' total [[electricity]].<ref name=wolfson>R. Wolfson. ''Energy, Environment and Climate'', 2nd ed. New York, U.S.A.: Norton, 2012</ref> In some countries around the world, hydroelectricity is the main type of electricity that is used.
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| Countries such as China, Canada, and Brazil are the leaders in total hydroelectricity generation with capacities of [[watt|200 GW]], 89 GW, and 70GW respectively.<ref name="RE1">Abhishek Shah. (September 2, 2015). ''List of World’s Largest Hydroelectricity Plants and Countries – China Leading in building Hydroelectric Stations'' [Online]. Available: http://www.greenworldinvestor.com/2011/03/29/list-of-worlds-largest-hydroelectricity-plants-and-countries-china-leading-in-building-hydroelectric-stations/</ref> Other notible producers include Russia, India, Norway, Japan, and Venezuela (which is almost completely dependent on hydropower).<ref name="RE1"/> See the data visualization below for more statistics on hydroelectricity in the world.
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| One of the benefits of hydroelectricity is that it is less polluting than using the [[combustion]] [[fossil fuel]]s for electricity. Although not free from [[emissions]] and other [[environmental impact]]s, they are significantly less [[pollution|polluting]] than other options. As well, hydroelectricity is relatively inexpensive once [[hydroelectric dam|dams]] and [[hydroelectric reservoir|reservoirs]] are built and these facilities can operate at very high [[efficiency|efficiencies]].<ref name="RE1"/> For more information on the ecological impacts of hydropower facilities, see: [[water quality degradation]] and [[environmental impacts of hydropower]].
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| ==Generation==
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| Hydroelectricity is generated at a [[hydroelectric facility]] - generally for large-scale generation this includes a [[hydroelectric dam]]. At these facilities, a dam holds back a large quantity of water, creating a reservoir. This reservoir holds water at a higher elevation than the rest of the original body of water (generally a river). This means that compared to the water in the river, the water in the reservoir has more potential energy. When a gate is opened at the top of the dam, the water flows through channels called [[penstock]]s down to the [[hydro turbine|turbines]]. When the water reaches the turbines, its kinetic energy gained from falling is transferred to the rotational motion of the turbines. As the turbines spin, they move a [[generator]] and generate electricity. This is how [[hydropower]] (the power of water) creates hydroelectricity.
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| Although hydroelectric facilities that have large outputs generally use dams, there are some types of systems that do not utilize dams and have very little [[water storage]] (meaning there is no real reservoir of water). These types of systems are known as [[run-of-the-river systems]], and are gaining popularity recently as alternatives to large scale reservoir dams.
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| ==Classifications==
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| Conventional hydroelectric generation relies on a head difference created by man-made dams and obstructions. The majority of current generation is conventional. Two types of systems that are considered conventional are hydroelectric dams and [[tidal dam]]. Unconventional generation techniques generally rely on flow rate or on a small head differential. These platforms produce less energy than conventional methods however they also have less impact on the surrounding environment. Some examples of unconventional hydropower platforms are [[low head hydro]], run-of-the-river systems, [[Instream microhydro power generator|instream hydro]], and [[kinetic tidal]].
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| Each type of hydroelectric generation method has an associated output classification based on its capacity. They are outlined in the table below.<ref>IPCC. (September 2, 2015). ''Chapter 5 - Hydropower'' [Online]. Available: www.ipcc.ch/pdf/special-reports/srren/drafts/SRREN-FOD-Ch05.pdf</ref>
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| <center>
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| {| class="wikitable"
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| ! Classification !! Capacity
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| | Large || > 100 MW
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| | Medium || 15 - 100 MW
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| | Small|| 1 - 15 MW
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| | Mini || 100 kW - 1 MW
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| | Micro || 5 - 100 kW
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| | Pico || ~ 200 W - 5 kW
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| |}
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| </center>
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| ==World Electricity Generation: Hydroelectricity==
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| The map below shows which primary energy different countries get the energy to generate their electricity from. Hydroelectricity is seen in blue. Click on the region to zoom into a group of countries, then click on the country to see where its electricity comes from. Some notable countries include China, Canada, Brazil, Russia, India, Norway, and Venezuela.
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| <html><iframe class='charts-iframe' id='world-energy'></iframe></html>
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| ==References==
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| {{reflist}}
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