The British government said Wednesday it was opening talks on plans to build the world’s first man-made tidal lagoon in Wales to generate green energy.
The Severn Estuary holds the second highest tidal range in the world and within this Swansea Bay benefits from an average tidal range during spring tides of 8.5m. The construction of a tidal lagoon to harness this natural resource would help the UK transition a low carbon future with greater energy security and lower electricity costs, while providing regenerative economic and recreational benefits to the local community.
A tidal lagoon is a harbour type structure closing off a tidal sea area, and incorporating hydro turbines through which the sea moves to generate electricity.
The world’s first, man-made, energy-generating lagoon would generate 320MW installed capacity and 14 hours of reliable generation every day. The clean, renewable and predictable the lagoon would power 155,000 homes (equivalent to 90% of Swansea Bay’s annual domestic electricity use) for 120 years.
Tidal lagoons are a simple concept involving the adaptation of standard, proven components used in global engineering projects. The Swansea Bay lagoon will comprise a UK standard sand-core breakwater or rock bund, similar to many seen in coastal defence schemes and harbour walls. The generating equipment of bulb hydro turbines have been used for many years on run-of-river hydro power schemes as well as some landmark tidal barrages. The hydro turbines are mounted inside concrete turbine housings and are permanently submerged so the resulting view is of a ring-shaped harbour wall with one section of concrete casing.
As the sea outside the breakwater rises and is held back a difference in water levels is created, known as ‘head’, and once a sufficient head height is reached sluice gates are opened and water flows into the lagoon through turbines to generate electricity. This process then occurs in reverse, on the ebb tide, as sea levels start to fall and a tidal head is created by holding water back within the lagoon. This way the tides can flow through our turbines four times daily to generate power.