The Great Barrage Debate

PUBLISHED: 14:13 30 December 2007 | UPDATED: 14:58 20 February 2013

La Rance tidal barrage in Brittany was built in the '60s

La Rance tidal barrage in Brittany was built in the '60s

Supporters of the Severn Barrage say it could help solve our growing energy crisis, but is it too high a price to pay? Opinion on the proposed Severn Barrage scheme is well and truly split down the middle. It's been called 'visionary' and 'trail b...

The UK's coasts and estuaries are a natural focus for tidal power proposals, but estuaries are crucial for wildlife too. The Severn Estuary, which lies at the mouth of four major rivers - the Severn, Wye, Usk and Avon - is an outstanding, relatively wild ecosystem. It is listed as a wetland of international importance, and is designated as a Site of Special Scientific Interest (SSSI) and a Special Protection Area (SPA).

The mud and sand here is home to a myriad of invertebrates and is a winter feeding ground for around 100,000 wading birds and wildfowl. Seven species of migratory fish move through here between sea and rivers.

So while wildlife groups support a switch to renewable energy, they want to be sure that building a barrage here would not be at the expense of the natural environment.

Recently the government has reopened the debate by announcing a study to examine the feasibility of generating electricity from the estuary using the technology of a hydro-electric dam. The investigation would consider the social, economic and environmental aspects of the £15 billion scheme; John Hutton, Secretary of State for Business, has called for 'open minds' on the subject.

A barrage over the Rance, near St Malo in Brittany, has generated tidal power for 40 years, but creating a structure across the Severn - producing as much electricity as two nuclear power stations - would be a major engineering feat which was unparalleled in scale.

A 10-mile-long concrete barrage stretching from Brean Down to Lavernock Point in Wales is considered to be the most cost-effective route for such a structure. It would create clean, renewable energy from tidal water, which would be trapped and, when released, used to power turbines.

In 1989, a proposal from the Severn Tidal Power Group (a consortium of engineers from Sir Robert McAlpine, Balfour Beatty, Taylor Woodrow and Alstom) claimed their barrage could provide at least 5% of the UK's electricity for about 120 years, create thousands of jobs, increase transport links between Somerset and South Wales and boost tourism in the area. The group also considered a longer and costlier route for a barrage between Barry and Minehead.

In 2006 Welsh businessman Gareth Woodham drew up plans for The Severn Lake Project - the development of an Energy Causeway from Brean to Wales. This would create a 360-acre lake in the Bristol Channel and feature two locked shipping channels, four marinas and a lifeboat station. No roadway or public railway is contained within the planning application, which includes 200 hydro-electric turbines, two wave farms and robotically controlled landfill cellars.

The barrage could provide at least 5% of the UK's electricity for about 120 years

Gareth Woodham says, "The people of the South-west and Wales need to face up to the fact that the choice is stark. Either we have renewable energy or two or three nuclear power stations. I know which I would want."

Roger Hull of the Severn Tidal Power Group says their plan for a 10-mile-long (16km) barrage with potential road and rail links, and a lock system big enough for Avonmouth's largest ships, would take six years to build.

"We guess it might take five years to get to the point where construction can start. Even so, the barrage would produce power well before 2020. The government has a commitment to produce 20% of our energy from renewables by 2020, so 5% of our electricity from a barrage would help a lot."

Fears that a barrage could cause flooding are disputed by Roger Hull.

"High-tide levels downstream of the barrage will be slightly lower than at present, as the studies for the 1989 report determined. I know some people have said the opposite, but that is not the case. So the Somerset Levels would not be flooded."

While some believe a barrage, with links to Wales and increased sailing opportunities, will transform the local economy, others believe lagoon-based structures (said to have less of an impact on the marine environment) would be a better option than a barrage, and the Somerset Wildlife Trust (SWT) wants the feasibility study to consider all options for harnessing tidal power.

"A tidal barrage would fundamentally alter the estuary and have a devastating effect on this unique ecosystem," says Lisa Schneidau, Head of People and Wildlife Programmes at the SWT. "It would no longer be able to support the wildlife features for which it was designated. Somerset Wildlife Trust believes that these impacts could not be mitigated against, to any acceptable level.

"The UK government has already made binding legal commitments at international and European level to maintain the ecological character of the Severn Estuary. The Wildlife Trust believes that construction of the Severn Barrage would make the UK the first government to renege on such commitments.

While wildlife groups support a switch to renewable energy, they want to be sure that building a barrage here would not be at the expense of the natural environment

"The carbon footprint made by construction of a barrage would be enormous and the footprint of other likely infrastructure developments (roads, railways, business parks, etc) would be even greater."

Then there is the famous Severn Bore - a huge tidal surge and spectator attraction, which could be weakened by a barrage.

Residents in Brean worry about the compulsory purchase of land and the years of disruption during construction. They fear that a road/rail link will be built across large caravan sites and holiday areas, which could lose millions of pounds from the local tourist economy. Brean is home to one of Somerset's popular beaches and locals want to know how a barrage might affect the sands if tidal flow changes.

"Most people recognise that hydro power is preferable to other methods, such as wind power and nuclear, for the effects on the environment," says Brean Parish Council . "We wish the government to consider alternative sites, ie south of Minehead, at Bossington - a longer crossing but one which avoids many of the problems."

The Sustainable Development Commission (SDC) is a government independent advisory body which has laid down tough conditions that a barrage would have to meet in order to be considered sustainable. These include public leadership and ownership of the project, and full compliance with environmental legislation protecting the estuary.

"The enormous potential for a Severn Barrage to help reduce our carbon emissions and improve energy security needs to be balanced against the impact on the estuary's unique habitat, as well as its communities and businesses," says SDC chair Jonathon Porritt. "We are excited about the contribution a Severn Barrage could make to a more sustainable future, but not at any cost." BY SARAH FORD

Do you think the Severn Barrage would be an environmental godsend or a catastrophe? Air your views on the Forum.

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