Severn Barrage and tidal energy

6 September 2007

There are cheaper and less environmentally damaging ways to generate power from the Severn Estuary than a tidal barrage

The tidal range in the Severn Estuary is one of the highest in the world, reaching over 13 metres, and ideas for taking advantage of energy generation have long been suggested.

The proposed Severn Barrage project would stretch nearly 10 miles from Lavernock Point west of Cardiff to near Brean Down in Somerset. It would cost around £14 billion.

Construction of the 60 million tonne structure, including 370 reinforced concrete caissons totalling 17 million tonnes, would take until 2019 at the earliest. It would enclose around 185 square miles of the estuary.

Why would the Barrage be environmentally damaging?

• The Barrage wall would create a 5 metre deep lake to its eastward side, losing an inter-tidal habitat, feeding grounds for tens of thousands of birds
• The Barrage would halve the tidal range and sensitive flora and fauna would be lost, and the famous Severn Bore diminished
• The Barrage could also have a significant impact on fish species of conservation interest, through use of fish sluices within the barrage wall
• The Barrage could significantly damage the viability of ports. It would also generate new traffic on existing road networks around Lavernock and Cardiff airport and cause development pressures in rural Somerset
• The government's own statutory advisers state that 'a Severn Barrage project would not be possible within the current legal framework provided by the EU Habitats and Birds Directives. The estuary is also being proposed for designation as a Special Area of Conservation (SAC), the highest protection in European Union law

Why the Severn Barrage will not address our needs

• The Barrage project cannot be justified on coastal protection grounds as coastal flood defence schemes can be built relatively quickly and sea level rises are forecast to take decades to a century or more to rise to a point at which they would be needed
• Alternative investments would reduce carbon more quickly in the next few critical decades
• The Barrage's huge twice-daily three hour pulses of power would not synchronise with the daily variations in grid demand, resulting in costly stand-by capacity
• The Barrage itself could cause coastal erosion or flood risk on its seaward side

Alternative low-carbon solutions

• Tidal lagoons: electricity generating lagoons located about a mile off the Severn coast
• Shoots barrier or barrage: A shorter flood defence barrier or a barrage near the Second Severn Crossing
• Other marine technologies: eg marine current turbines in the Bristol Channel
• Wind energy: about 1,000 offshore 5 MW wind turbines would generate the same annual output as the Barrage project
• Carbon Capture and Storage (CCS): CCS fitted to coal or gas power stations would reduce their emissions by 85-90%

Friends of the Earth Cymru believes there are environmentally benign ways to generate tidal energy from the Severn Estuary. To destroy a unique, internationally important and protected conservation area to generate just one percent of UK energy is not the way forward.

Download Friends of the Earth Cymru's Severn Barrage report  (PDF†)