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A Severn Barrage would harness the power of the Severn Estuary using hydro-electric dam technology filled by the incoming tide rather than by water flowing downstream.

The project's potential to provide 5% of total UK electricity demand from a renewable, British source will be examined alongside the impact on the natural environment, and social and economic aspects as well as the financing. The study will also look at the potential for other UK barrages.

John Hutton said:
"The Government will drive forward with delivering a step change in our use of renewable energy and will now start work on the feasibility of a Severn Barrage.

"This is a truly visionary project, unparalleled in scale, potentially generating 5 per cent of the UK's electricity from renewable sources. As we undertake this work, we must understand the true environmental, social and economic impacts of such a project. They are potentially considerable.

"But so too is the challenge of climate change. And we must all have open not closed minds about how we meet the energy needs of tomorrow."

The news was given a cool response from environmentalists who have expressed concerns over the technology.  In particular the Wetlands and Wildlife Trust are concerned that the barrage would significantly damage existing wetlands which provides food for over 85,000 migratory and wintering birds.

Martin Spray, WWT's Chief Executive, said:
"WWT fully backs a shift toward low-carbon energy sources and recognises the potential benefits of harnessing the power of the massive movement of water in and out of the Severn Estuary each day.

"However the construction of a huge dam across the estuary could have a massive environmental impact on this delicate ecosystem and the wildlife that depends on it. There are alternative methods of harnessing that tidal power and WWT is calling for fair and balanced assessment of all the options and implications for the estuary’s international conservation importance so the best deal can be struck for people and wildlife."

Reacting to the news, Greenpeace executive director John Sauven said:
"Tidal power can provide the UK with a tremendous amount of energy along with other marine renewables like wave power. And, importantly, it can do so without creating dangerous climate change emissions or nuclear waste. The Severn barrage could be a huge resource of carbon free energy, but the jury's still out on the best way to reap the tidal power of the river without having huge environmental impacts on wading birds.

"Offshore wind, as a cheaper option, should also be much higher up the government's priority list. The UK has about 40% of Europe's wind resource which could be harnessed to meet our demand for energy. For example the London Array, in the Thames estuary, will supply 750,000 homes in London at a cost of around ?1.5 billion."

Alternative Systems
The alternative method Spray refers to is a system based on lagoons.  They would be much less disruptive than a barrage, but there are question marks over its efficiency and cost effectiveness.

The problem for the barrage is that, while it would not block the flow of water, it would be a physical block for the movement of silt, essential for the viability of the wetlands along the Severn.

The Severn Estuary is one of the largest estuaries in the UK. Its funnel shape, unique in the UK, helps give it the second highest tidal range in the world at more than 14 metres, bringing with it huge reliable energy potential, but any method for capturing its energy needs to have as little impact as possible on the natural flows of water, silt and wildlife.  At the same time it mustn't interfere with navigation along the estuary.

Various alternatives to invasive barrage systems include underwater windmills or a hydroplane called the Stingray, created by Northumberland based, The Engineering Business.

John Hutton has also announced that he will establish and chair a new Ministerial committee which will include representation from interested Departments and the Welsh Assembly Government to take forward this work and ensure appropriate governance.