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Tidal Energy
        
Background
 
Tides, the daily rise and fall of ocean levels relative to coastlines, are a result of the gravitational forces of the moon and sun as well as the revolution of the earth. The principle of harnessing the energy of tides dates back to as early as the Middle Ages, when the phenomenon of tides was not yet explained and were used to turn waterwheels, producing mechanical power. A large amount of energy is stored in tides and it is possible to tap into this renewable resource with tidal power plants. Tidal electricity generation involves the construction of a barrage across a delta, estuaries, beaches, or other places that are affected by the tides [1].
 
How it works
 
Specifically, the barrage (dam) blocks the incoming and out-going tides of a coastal basin. The barrage is equipped with sluices and turbines that will permit the retention of water entering at high tide and release it at low tide; normal turbines will produce electricity as the water flows out; reversible blade turbines, however, can produce electricity both as the water enters the basin and when it leaves. The basic difference between a hydraulic power plant on a river and a tidal power plant is this two-directional flow [2]. If navigation to the upper part of the basin is necessary, a ship lock may be installed.
 
To date, relatively few tidal power plants have been constructed. Of these, the oldest and by far the largest is the La Rance 240 megawatt barrage located near St. Malo, in Brittany, Northern France [3]. This tidal power plant was built for commercial production and came into service in 1966. It is highly automated, requiring only two people to operate it on weekends and in the evening, [4] and furnishes 90% of Brittany's electrical needs. After completing over 30 years of reliable operation, the power plant is undergoing a $78 million renovation. To provide uninterrupted power production, the plant's 24 turbines are being upgraded one at a time over a 10 year period [5].   See More...
 
 
 
 
TitleMARINE CURRENT ENERGY  ( WEBSITE )
Descriptionhe strength of the marine currents generated by the tide vary, depending on the position of a site on the earth, the shape of the coastline and the bathymetry (shape of the sea bed). Along straight coastlines and in the middle of deep oceans, the tidal range and marine currents are typically low. Generally, but not always, the strength of the currents is directly related to the tidal height of the location. However, in land-locked seas such as the Mediterranean, where the tidal range is small, some sizeable marine currents exist.
KeywordsTIDES; TIDAL; ENERGY
Geography KeywordsGLOBAL; OCEANS
Content Language(s)English
Web Address (URL)http://www.worldenergy.o ... arine.asp
Type of WebsiteInstitutional website
Access RightsWorld Energy Council
Part Of2935
  
1076 Topics - 5135 Related Knowledge - 2534 Members - 34 Editors
generationTime:2005/01/13 12:23:26