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A tidal barrage is a dam-like structure used to capture the energy from masses of water moving in and out of a bay or river due to tidal forces.〔(【引用サイトリンク】url=http://www.esru.strath.ac.uk/EandE/Web_sites/01-02/RE_info/Tidal%20Power.htm#barrage )〕〔(【引用サイトリンク】url=http://www.rise.org.au/info/Tech/tidal/index.html )〕 Instead of damming water on one side like a conventional dam, a tidal barrage first allows water to flow into a bay or river during high tide, and releasing the water back during low tide. This is done by measuring the tidal flow and controlling the sluice gates at key times of the tidal cycle. Turbines are then placed at these sluices to capture the energy as the water flows in and out.〔 Tidal barrages are among the oldest methods of tidal power generation, with projects being developed as early as the 1960s, such as the Kislaya Guba Tidal Power Station in Kislaya Guba, Russia. == Generating methods == The barrage method of extracting tidal energy involves building a barrage across a bay or river that is subject to tidal flow. Turbines installed in the barrage wall generate power as water flows in and out of the estuary basin, bay, or river. These systems are similar to a hydro dam that produces Static Head or pressure head (a height of water pressure). When the water level outside of the basin or lagoon changes relative to the water level inside, the turbines are able to produce power. The basic elements of a barrage are caissons, embankments, sluices, turbines, and ship locks. Sluices, turbines, and ship locks are housed in caissons (very large concrete blocks). Embankments seal a basin where it is not sealed by caissons. The sluice gates applicable to tidal power are the flap gate, vertical rising gate, radial gate, and rising sector. Only a few such plants exist. The first was the Rance Tidal Power Station, on the Rance river, in France, which has been operating since 1966, and generates 240MW. A larger 254MW plant began operation at Sihwa Lake, Korea, in 2011. Smaller plants include one on the Bay of Fundy, and another across a tiny inlet in Kislaya Guba, Russia. A number of proposals have been considered for a Severn barrage across the River Severn, from Brean Down in England to Lavernock Point near Cardiff in Wales. Barrage systems are affected by problems of high civil infrastructure costs associated with what is in effect a dam being placed across estuarine systems, and the environmental problems associated with changing a large ecosystem. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tidal barrage」の詳細全文を読む スポンサード リンク
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