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Frequently asked questions

 

What is a barrage and why would we want one?

A barrage would provide 5% of Britain's electricity in a renewable, carbon-free form. It would also provide a valuable river crossing and represent a boost for the economies and tourism in both Wales and South West England.

A barrage is a construction built with the purpose of extracting tidal energy. Turbines generate as water flows in and out of the estuary or river. When the water level changes relative to the water inside, the turbines are able to produce power (as demonstrated in the proposed pictures of the Severn Barrage). It works by trapping water behind it at high tides and releasing it through the turbines.

 

Where is the Severn Estuary?

The Severn Estuary has the second largest tidal range in the world - about 15 metres (49 ft), exceeded only by the Bay of Fundy. The River Severn extends down to the Second Severn Crossing. The Severn Estuary begins at this point and stretches to a line from Lavernock Point (south of Cardiff) to Sand Point, Brean Down near Weston-super-Mare.

 

How much would it cost?

£15 million is the estimated figure for building the Severn Barrage. All of this money would have to be publicly funded.

 

Would this be the first barrage of its kind?

There are currently only three operating plants globally: Rance River, Bay of Fundy and Kislaya Guba. The largest plant is on the Rance River in France which was installed in 1966. There have been many previous proposals for barrages which have been rejected and plants that have ceased operation.

 

What is the feasibility study?

The study is expected to last two years, with the cost estimated at around £9 million. It will be split into two stages with a decision point at the end of each. The first, which is likely to run until late 2008, will focus on high level issues and reach an initial view on whether there are any fundamental issues that would preclude a tidal scheme in the Severn Estuary. Subject to the decision at the end of the first phase, the second phase will look at the issues in more detail and culminate in a full public consultation in early 2010. A Strategic Environmental Assessment will be an important part of this process.

 

What is the Severn Bore?

The Severn bore arises as a result of the river’s estuary emptying into the Bristol Channel, and during the highest tides, the rising water is funneled up into a wave that travels rapidly upstream against the current. Being the onset of the flood tide it is accompanied by a rapid rise in water level which continues for about one and a half hours after the bore has passed. The largest bores occur in spring, but smaller ones can be seen throughout the year. River surfing enthusiasts even attempt to surf along on the wave, which can be 2 metres (7 ft).