Perhaps the most famous hydroelectric schemes are the Snowy Mountains Scheme in Australia and the [Hoover dam]? in the USA, although the concept is highly scalable to very small and very large projects.
A typical hydro-electric scheme consists of a dam behind which a reservoir? of water is held. When electricity is in demand, valves will be released, allowing the water to flow downhill to a [power station]? where turbines will be made to turn by the force of the water flow. Connected to generators, electricity can be produced. The water is then allowed to return to the original riverbed or a nearby river.
A variation on this idea is the pumped-storage system, where a lower reservoir also exists. At peak demand times, the system generates electricity as normal. At times of lower demand the process can be reversed and the water is pumped back up into the higher holding reservoir for use at another peak period.
Some hydroelectric systems use the natural flow of water over an existing waterfall?, with no dam needed; for example, a large amount of electricity is generated by diverting part of the water that flows over [Niagara Falls]?.
Environmental considerations include the flooding of the dam area; the agricultural and wildlife water needs downstream; and flushing of agricultural and other run-offs from the river system.
Would wave power be considered hydroelectricity?
![[Home]](wikipedia.png)