Усны эрчим хүч: Засвар хоорондын ялгаа

have the potential to generate 20% of the electricity used in 2012.<ref>[http://www.darvill.clara.net/altenerg/tidal.htm Energy Resources: Tidal power]</ref>

 

 

{{See also|List of largest power stations in the world|List of largest hydroelectric power stations}}

 

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Small hydro is the development of [[hydroelectric power]] on a scale serving a small community or industrial plant. The definition of a small hydro project varies but a generating capacity of up to 10 [[megawatt]]s (MW) is generally accepted as the upper limit of what can be termed small hydro. This may be stretched to 25 MW and 30 MW in [[Canada]] and the [[United States]]. Small-scale hydroelectricity production grew by 28% during 2008 from 2005, raising the total world small-hydro capacity to {{nowrap|85 [[Gigawatt|GW]]}}. Over 70% of this was in [[China]] ({{nowrap|65 GW}}), followed by [[Japan]] ({{nowrap|3.5 GW}}), the [[United States]] ({{nowrap|3 GW}}), and [[India]] ({{nowrap|2 GW}}).<ref>[http://www.ren21.net/globalstatusreport/download/RE_GSR_2006_Update.pdf Renewables Global Status Report 2006 Update], ''[[REN21]]'', published 2006</ref>

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 network, or in areas where there is no national electrical distribution network. Since small hydro projects usually have minimal reservoirs and civil construction work, they are seen as having a relatively low environmental impact compared to large hydro. This decreased environmental impact depends strongly on the balance between stream flow and power production.

 

 

Micro hydro is a term used for [[hydroelectric power]] installations that typically produce up to {{nowrap|100 [[Kilowatt|kW]]}} of power. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks. There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without purchase of fuel.<ref>{{cite web|url=http://www.tve.org/ho/doc.cfm?aid=1636&lang=English |title=Micro Hydro in the fight against poverty |publisher=Tve.org |date= |accessdate=2012-07-22}}</ref> Micro hydro systems complement [[photovoltaics|photovoltaic]] solar energy systems because in many areas, water flow, and thus available hydro power, is highest in the winter when solar energy is at a minimum.

 

 

Pico hydro is a term used for [[hydroelectric power]] generation of under {{nowrap|5 [[Kilowatt|kW]]}}. It is useful in small, remote communities that require only a small amount of electricity. For example, to power one or two fluorescent light bulbs and a TV or radio for a few homes.<ref>{{cite web|url=http://www.t4cd.org/Resources/ICT_Resources/Projects/Pages/ICTProject_287.aspx|title=Pico Hydro Power|publisher=T4cd.org|accessdate=2010-07-16}}</ref> Even smaller turbines of 200-300W may power a single home in a developing country with a drop of only {{Convert|1|m|ft|0|abbr=on}}. 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.

 

{{Main|Underground power station}}