Plans to generate electricity from the world’s first series of tidal lagoons have been unveiled in the UK. The six lagoons – four in Wales and one each in Somerset and Cumbria – will capture incoming and outgoing tides behind giant sea walls, and use the weight of the water to power turbines. A £1bn Swansea scheme, said to be able to produce energy for 155,000 homes, is already in the planning system. Energy Secretary Ed Davey says he wants to back the project.
The cost of generating power from the Swansea project will be very high, but the firm behind the plan says subsequent lagoons will be able to produce electricity much more cheaply. It says the series of six lagoons could generate 8% of the UK’s electricity for an investment of £30bn. As well as Swansea, the proposed lagoon sites are Cardiff, Newport, and Colwyn Bay in Wales; Bridgwater in Somerset; and West Cumbria. Each will require engineering on a grand scale. In Swansea, the sea wall to contain the new lagoon will stretch more than five miles and reach more than two miles out to sea.
How does tidal lagoon power work?
The lagoons operate a system similar to a lock gate to alter the water level either side of a sea wall. When the tide starts to rise, gates in the wall are closed and water builds up outside the lagoon. When the tide is full outside the lagoon, the gates are opened and water rushes past the turbines to fill up the lagoon. When the tide turns to go out, the gates are shut to hold the water inside the lagoon. As low tide is reached outside the wall, the gates are opened to generate power again as water flows through from the raised water level in the lagoon. Edited from World’s first lagoon power plants unveiled in UK.