Barrage of support for tidal lagoons

Letters to The Guardian, Monday May 1, 2006

There is no doubt that the tremendous tidal range found in the Severn estuary should be harnessed for energy. It is predictable, constant and renewable (Estuary energy plan makes waves, April 26). But while the barrage solution is fraught with difficulties, several of which were mentioned in your article, tidal lagoons are a proven technology - as David Sainsbury, the DTI minister, has said.

A tidal lagoon, which looks like a small rocky island, is a constructed lagoon with turbines embedded in the walls capturing energy as the water flows in and out of the structure with each rising and falling tide. The cost of these lagoons is such that for the same price as the proposed Severn barrage at least 150 lagoons could be constructed. Estimates show generation costs from the barrage of 5.5 pence and from lagoons 2.5 pence per kilowatt hour. Lagoons can also be built in close proximity to the communities using the power, cutting transmission loss and building a decentralised system.

Lagoons, with their far more reasonable capital costs, will find it easier to raise the investment needed. As Ofgem says in its report: "There is considerable potential for this technology in the UK, Canada and China." And, as your article stated, the environmental price will be substantially lower. Indeed, given the environmental impact, there is a good chance the barrage will never happen.

The impact of lagoons on inter-tidal wildlife would be minimal and it would be far more efficient at controlling the generation of electricity to match demand. It has many of the benefits and none of the side-effects of the plan for a barrage. Tidal lagoons are supported by Friends of the Earth and would generate approximately 7% of current UK energy requirements. The company which has put forward the plans has been commissioned to build lagoons in China and has plans for others in Swansea.

Will McNeill , London

Tidal lagoons are a technically viable, affordable and environmentally benign source of power which the UK, and Wales, specifically, are uniquely placed to exploit. Lagoons could potentially meet the government's 2010 target of 10% renewable energy. They use tried and tested hydroelectric technology and past criticisms have turned out to be unsubstantiated.

Jon Aldenton, The Environment Trust