The tidal lagoon scheme
A 9km U-shaped breakwater would be built across Swansea Bay, creating a lagoon. At lower states of the tide, the tidal lagoon looks like a typical rubble mound breakwater, of the type usually seen around marinas or harbours. At high tide it is more or less submerged.
As tides rise and fall the lagoon would fill and empty. Gates would hold back the water from entering or leaving until the optimal point. Once opened the water would rush though the gates, turning a bank of 16 six-metre tall hydro turbines in the breakwater to generate 350mw of electricity – enough for 150,000 homes.
The turbines would generate electricity both when the tide ebbs and flows. The Bristol Channel is favoured because of its unusually high tidal range, which at 15m is among the highest on the planet.