Tidal Power for the Severn - the Next Stage

As previously reported in this blog, The Sustainable Development Commission last year carried out a comprehensive study of tidal power in the UK, with a significant amount of this research focused on the Severn Estuary.

The background to this report, of course, is the attempt to shift the balance in the UK from a carbon-based to a renewable-based model of energy supply.

As far as the Severn is concerned, the report focuses on two main areas: tidal power and barrage technology with, it is claimed, the potential for 10% of the UK's electricity to be produced by these two forms of technology.

A barrage in the Severn Estuary could, according to the SDC, supply over 4% of the country's electricity supply for 120 years resulting in "significant climate change and energy security benefits."

A barrage is effectively a dam across the estuary. As the tide rises, water flows into the area behind the barrage. As the tide ebbs, the barrage keeps the trapped water behind it until low tide, when its sluice gates are opened and water pours down to the low tide level, turning turbines in the process and generating electricity.

A major concern with any barrage is the impact on the local environment and this is highlighted in the report, which estimates that such a scheme would result in the loss of up to 75% of the Severn's internationally-protected inter-tidal habitat. There would also be a number of impacts on local communities and the regional economy. Furthermore, such a barrage would tend to become an easy focal point for further development either side of the river. In fact, discussions about a road being built across the barrage (effectively a third Severn crossing) or a rail track are already underway.

The SDC has therefore laid down a series of conditions which a Severn barrage would have to meet in order to be considered sustainable. These include:

• The barrage must be publically owned
• alternative wildlife habitats must be created "on an unprecedented scale". [I think that means relocating Slimbridge, among other things.]
  

In short, the SDC seem to be saying that they think a barrage would be a good thing from the point of view of sustainable energy subject to specific environmental safeguards and that they would like this to progress to the next stage of public debate and discussion.

The report is much more vague on the prospects of tidal stream technology - essentially underwater turbines that are turned by the ebb and flow of the tide. Acknowledging that "the UK has an excellent tidal stream resource, and is leading the world in the development of a wide range of tidal stream devices", the SDC goes no further in its recommendations than to urge the UK to "stay the course" in developing these technologies, as the climate change benefits are potentially very large.

Recommendations for a specific programme of investment in this technology and its application to the Severn are distinctly lacking, despite its significantly lower environmental impact.

In summary, it's the barrage which looks the most likely to be recommended, though of course there are numerous issues to discuss and resolve before this project even reaches the planning stage.

Your opinions, as ever, welcome via the comments button below.

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