A proposal that could generate five per cent of the UK's electricity from the tidal movements in the Severn Estuary has made a government shortlist for a tidal power project in the area.
The ten mile barrage – a construction similar to a dam with turbines in it – would span the estuary from Cardiff to Weston super Mare.
It would generate 8.5 gigawatts of electricity, twice the amount currently generated by the UK's largest fossil fuel plant.
Ed Miliband, secretary of state for energy and climate change, said: "The Severn estuary has massive potential to help achieve our climate change and renewable energy targets. We want to see how that potential compares against the other options for meeting our goals.
"The largest proposal to harness the power of the tides on the shortlist could save as much carbon dioxide as all the residential emissions from Wales."
Two other barrages are among the final five proposals being considered by the government, along with two lagoon projects.
The government has also announced it is making £500,000 available to develop other tidal technologies.
We are developing an eight megawatt tidal stream project off the west coast of the UK, which will power the equivalent of 5,000 homes.
