GC: n
CT: There are currently no tidal barrages in the UK. The most promising site in the UK would be across the Severn estuary. A barrage across the Severn estuary could supply up to 5% of the UK’s electricity requirements.
However, this would also be very expensive to construct. Also if a barrage was built across the Severn, sewage and other waste from many places would linger instead of being easily carried out to sea.
The tidal barrage across the La Rance River in France is the only major tidal power station in Europe. The 240 MW (megawatt) barrage was built in 1966 and took 5 years to complete.
S: http://www.brightknowledge.org/knowledge-bank/geography-and-environment/features-and-resources/tidal-barrages (last access: 26 February 2015)
N: 1. Barrage Tidal is a capital intensive method for generating tidal power. A barrage is similar to a hydroelectric dam, but differs in a few key ways. The barrage is essentially a large concrete structure that spans an estuary basin, bay or river with gates (sluices) that enable waves to move in and out of the dammed area. At high tide, the sluices are closed. Once the tide shifts directions and ebbs, the sluices are opened allowing the higher water levels in the basin to flow through the barrage and pass the hydroelectric turbine on its way out to sea. Once emptied, the basin is refilled when the tide flows back to shore.
2. Tidal Barrage is a dam or causeway across a river that has sluices and turbines that control the flood and ebb of the tides to drive the turbines and generate electricity.
Barrages are simple, they use proven hydro turbine technology and already exist in France, Canada, Russia and Korea. Tidal Barrages in the Severn and selected rivers in the east Irish Sea could produce 15% of the UK’s electricity.
The most notable is the La Rance Barrage near St Malo in France which has been in place for 43 years.
We need all possible Renewable Energy sources and all those above may have a part to play. Barrages are the most efficient tidal energy resource and they are an important part of our energy solutions.
3. Tides flow in and out of estuaries and rivers on a cycle of approximately 12.4 hours, 2 tides every 24 hours and 50 minutes. The tides are caused primarily by the gravitational pull of the moon but the sun has a secondary effect which is why tides vary in height through the year. When the moon and sun are aligned and pull together we get high very high or Spring tides and when they are opposed we get very low or Neap tides.
The tides are 100% predictable and therefore offer a completely reliable energy source.
Energy is taken from the tidal water movement by building a dam across a river with sluices and turbines. The revolution of the turbines is used to generate electricity. There are a variety of turbine designs and they can be designed to operate in both directions – ebb and flow.
S: 1. http://greenthefuture.com/TIDALPOWER_HOWITWORKS_BARRAGE.html (last access: 26 February 2015). 2 & 3. http://www.wyretidalenergy.com/tidal-barrage (last access: 26 February 2015).
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