Ambitious plans to build a fleet of giant tidal lagoons capable of providing up to 8% of the UK’s power have been unveiled.
The UK intends to generate renewable power from incoming and outgoing tides at six lagoons, four in Wales and one each in Somerset and Cumbria.
New sea walls stretching miles would be constructed at the proposed sites, where the weight of the water will be used to power installed turbines.
Energy Secretary Ed Davey says he wants to back the project.
One site, a £1bln project in Swansea Bay, is already in the planning system and is expected to generate enough power to electrify 155,000 homes.
The lagoon would have an installed capacity of between 1,800 megawatts (MW) and 2,800MW.
Developer, Tidal Lagoon Power, is currently in talks with the government about the charges to be fixed for the power supply to customers.
The lagoons will be funded by electricity bill-payers under the existing government scheme to boost domestic, low-carbon energy.
The cost of the combined sites is expected to be high, at an investment of £30bn.
Tidal Lagoon Power chief executive officer Mark Shorrock said: "It is admittedly rather expensive to begin with, but as time goes on and the capital costs are paid off it becomes incredibly cheap."
Energy entrepreneur Shorrock, who has already constructed 280MW of wind and solar plants, told the BBC he has potential financial backing from the Macquarie Group's (ASX:MQG) infrastructure funds and would like to bring in UK pension funds as investors.
He says the projects would be far cheaper and more productive than the £30bn Severn Barrage scheme which was first turned down by the government in 2010 amid huge opposition from many environmentalists.
Good Energy (LON:GOOD), a British renewable power supplier, invested £500,000 in Tidal Lagoon in May last year
For the first site, a full planning application could be submitted in 2017, and if it was approved it could start generating power in 2022.
Shorrock, who has already constructed 280MW of wind and solar plants, says he has potential financial backing from the Macquarie Group's infrastructure funds and would like to bring in UK pension funds as investors.
Power firms increasingly like the idea of tidal energy because, unlike power from the sun and wind, it is predictable.
Aim-listed Altantis Resources (LON:ALR), set up in 2010, is another company involved in the development of tidal power projects.
The firm’s MeyGen project in the Pentland Firth in the far north of Scotland in on course deliver a fully operational renewable energy plant of almost 400MW powered purely by the tide. First power is expected in 2016.