A coalition of researchers and energy companies have floated the idea of constructing a Severn tidal 'fence' instead of the controversial barrage that has been proposed for the river.
The Severn Tidal Fence (STF) Group, as they have named themselves, said the fence would consist of a continuous line of tidal current turbines in the Severn Estuary installed in a way which forces as much flow to go through the turbines as possible.
It would offer a compromise between the interests of conservation, clean power generation and the existing business needs in The Severn, the group said.
Proposals for a barrage in the estuary met with fierce criticism from environmental NGOs last year who claimed it would destroy large areas of wetlands that are a vital wildlife habitat.
However, a study by the Government-backed watchdog the Sustainable Development Commission said it could provide 5% of the UK's energy needs.
The STF Group, which includes Edinburgh University and renewable energy firms Econnect, and Pulse Tidal, said it has already carried out a preliminary investigation into a tidal fence.
It believes it would have a capacity of 1.3GW - slightly more than Sizewell B nuclear power station - and provide about 1% of the country's electricity supply.
In a statement, the group said: "There would be a large open channel for shipping near the Cardiff shore, smaller channels for small boats and no construction anywhere along the shoreline.
"The proposed tidal fence would therefore not prevent shipping reaching docks in Bristol or further upstream, it would not interrupt the migration of salmon, and it would only slightly reduce the areas of mudflats which are an important habitat for migrating birds.
"It would still, however reduce high tide levels enough to significantly reduce the risk of flooding."
Another possibility suggested by the group is a combination of a tidal fence with a small barrage or tidal lagoons.
The fence would then produce most power at the middle of the tidal cycle, whereas the barrage or lagoon would produce most power at high and low tide.
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