Tidal Power Generation

The Rance tidal barrage in Brittany was constructed sixty years ago. It is 750 metres long and encloses a basin of about nine square miles. At the time of building it cost the equivalent of approximately £95 million which was repaid in twenty years. It has now been operating for nearly sixty years and, with only routine maintenance, there is no reason why it cannot continue generating electricity for at least another sixty and maybe even further into the future.

The annual output from Rance is more than 500 GW (enough to power about 300,000 homes) operating at a capacity factor of 24%. The current cost of the electricity it produces is about £18/MW – less than half the cost of wind or solar power and about a sixth of the cost of gas-fired power stations.

Why doesn’t Britain try a similar system. This country is unique in being surrounded by tidal seas (some of the rises and falls being among the largest in the world). It also has a multitude of deep inlets and river estuaries. For example, Poole Harbour is about the same area as the Rance basin but the barrage necessary to enclose it would only be about half as long as at Rance. Of course, there would be a high capital cost, but it would be much less than a nuclear power station or a large off-shore wind farm. It would also have the secondary benefit of providing a permanent roadway between the Isle of Purbeck and the Bournemouth conurbation.

I am also aware of a smaller site, where the barrage already exists in the form of a sand-bar and where, at a cost of no more than couple of million, an experimental tidal power plant could be operating within a year of receiving permission.

If you wish to get in touch with me about any of the matters I raise in my blogs, you can contact me through my website or at mike@mikehillier.co.uk.

Mike.