In the last few years governments all over the globe have searched and developed ways to harvest tidal energy, taking into consideration their country position to the sea.
UK government recently made public a plan to start harvesting tidal energy in Severn Estuary were tides rise and fall twice a day up to 12 yards.
UK has investigated 10 schemes from which five have been selected over the last six months. The 5 potential schemes to start tidal harvesting in that area are as follows: the Bridgewater-Bay lagoon (impounds a section of coastal estuary to generate 1.36GW), the Fleming lagoon (a similar scheme on the Welsh shore), the Cardiff-Weston barrage (ten-mile stretch of land that could generate up to 5% of the UK’s energy needs), the Shoots barrage (upstream scheme that could generate 1GW), and the Beachley barrage (scheme above the Wye River that could generate 625MW).
The lagoons will be built from stone, rubble, and 9 foot high sausage-shaped bags filled with silt. The bags would create the lagoon wall which will be at least 12 yard high. The lagoons will fill with water twice a day as the tides come and go from the shores. Power will be generated though some turbines when water flows out of the lagoons.
Four of the schemes already received their environmental approval except Cardiff-Weston barrage because this dam will destroy thousands of acres of mudflats and salt marshes.
A two year feasibility study will be conducted from the government to assess the costs, benefits and impacts of a tidal scheme in the Severn Estuary and identify a single preferred project from the options that have been proposed.