View source for Tidal barrage

[[Category:Done 2015-07-24]] 
[[File:barragediagram.jpg|400px|thumb|right|Figure 1: At low tide, stored water flows out from the reservoir into the sea and turns the turbines.<ref name = ref99>Strathclyde University/Energy Authority of New South Wales</ref>]]
<onlyinclude>'''Tidal barrage''' systems are a [[tidal power]] generation method that work similar to [[hydropower]] and have sluices that control the tidal flow to drive [[turbine]]s and generate [[electricity]].</onlyinclude><ref name =Ref1>Wyre Tidal Energy. (Accessed July 27, 2015). ''Tidal Barrage'' [Online]. Available: http://www.wyretidalenergy.com/tidal-barrage</ref> 

==Benefits==
These types of dams can be used not only to produce [[renewable energy]], but also to reduce flooding. As the global effects of [[climate change]] becomes more evident, the world is faced with the very real threat of [[rising sea level]]s. Tidal barrages can be used to prevent flooding of low lying areas - areas that already are at a high risk of flooding - by holding back or releasing water as necessary.<ref name =Ref3>EcoSpark. (Accessed July 27, 2015). ''Tidal'' [Online], Available: http://www.ecospark.ca/wattwize/students/tidal</ref>

Furthermore, the [[Moon]] and [[Sun]] aren't going anywhere anytime soon (nor are their influence on the [[tidal force]]s) which means that we can easily produce this type of tidal power for as long as we need. This also means that tides are easily predictable and repetitive which allows us to know exactly when and how much [[power]] is attainable.<ref name=Ref4>Keith Cooley. (Accessed July 27, 2015). ''The Moon and Tides'' [Online], Available: http://home.hiwaay.net/~krcool/Astro/moon/moontides</ref>

==Drawbacks==
Tidal barrages alter the flow of saltwater in and out of estuaries, which can alter the quality of the seawater and thus negatively impact and displace marine life in the area.<ref name=Ref3 /> Furthermore, barrage systems have high development costs and it can be difficult to justify using so much capital especially when the [[environment|environmental]] threats are taken into consideration. 

The other, perhaps obvious, problem with tidal power is that you need tides. It is important to think of tidal power not as a one-off solution for the world's [[energy]] needs, but rather, to see it as a contributor to a low-[[carbon]] [[electricity generation portfolio]].

==Barrage Designs==
There are several different types and methods of producing [[electricity]] by tidal barrage. However, there are two main classes that are used. Typically the type or class used depends on the environmental circumstances of an area.<ref name =Ref5>KORDI Coastal Engineering Research Department. (Accessed July 27, 2015). ''Tidal and Tidal Current Power Study in Korea'' [Online], Available: http://www.energybc.ca/cache/tidal/KOREA.pdf</ref>

===Ebb Generation=== 
Ebb generation uses gates that allow the water to fill a basin to the normal level, these gates are then closed at full tide. The water is then held back for a few hours while the tide recedes, the gates are then opened and the water flows through turbines for several hours [[electricity generation|generating electricity]] through to low tide.<ref name =Ref6>Zou Fan, University of Gavle. (Accessed July 27, 2015). ''Tidal Power Energy'' [Online], Available: http://www.exergy.se/goran/hig/ses/06/tidal.pdf</ref>

===Two-way Generation=== 
Two-way generation uses turbines to generate power during both flood and ebb tide. All the [[water]] flows through the turbines and, unlike ebb generation, the water is not held back but allowed to flow freely and constantly turn the turbines. The energy produced is usually less than ebb generation but electricity is produced over a longer period of time, which can be beneficial depending on what the [[energy]] requirements are for a specific area.<ref name=Ref6 />

==Power Production==
[[File:LaRance.jpg|thumbnail|300px|right|Figure 2: Image of La Rance Tidal Power Station.<ref name=ref10/>]]
A great case study is the Rance Barrage (La Rance Barrage) - located in Brittany, France. It is the world's first tidal power station - and also has one of the highest capacities with a peak rating of 240 [[MW]]. Its annual output of approximately 600 [[Wh|GWh]] is lower than most traditional types of power plants such as [[nuclear power plant|nuclear]] or [[natural gas power plant|natural gas]], however, the cost per [[Wh|kWh]] is comparable to other forms of sustainable energy.<ref name=ref10>Wyre Tidal Energy. (Accessed July 27, 2015). ''La Rance Barrage'' [Online], Available:http://www.wyretidalenergy.com/tidal-barrage/la-rance-barrage</ref>

==References==
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