Wednesday, 26 November 2008

Bird charity backs Minehead reef as greenest option for Severn Estuary tidal power

A CORNISH company’s plan to build a ‘tidal reef’ from Minehead to Wales has won the backing of charity the Royal Society for the Protection of Birds (RSPB).
Engineering firm Joseph Evans and Sons Ltd, of Launceston, has proposed a 12-mile ‘Severn Tidal Reef’ (illustrated, right, and below) as an alternative to a 10-mile barrage from Weston-super-Mare to Cardiff.
The RSPB asked engineering consultancy Atkins to look at the feasibility of a ‘greener’ alternative to the barrage.
Now, the Atkins study has shown a reef a would be less damaging to the environment, would generate more power than a barrage, and would also be cheaper to build.
It found a reef would hold back about 6 ft 6 in of water without altering tidal patterns as much as would a barrage.
The Cardiff to Weston-super-Mare barrage is claimed to be able to generate 17,000GW of clean energy each year, equivalent to nearly five per cent of the UK’s electricity needs.
However, the research for the RSPB concluded the reef would produce 20,000GW of electricity while also costing about £2 billion less to construct.
Both the barrage and the reef would generate electricity as water flowed through turbines, but the reef would not hold back the full height of the tide as would a barrage.
The reef would also generate electricity for longer periods than the barrage, making it better able to meet peak demand times for electricity.
The RSPB said it preferred a reef because it would keep intact most of the estuary’s bird feeding grounds, while its slower-moving turbines would reduce danger to migrating salmon and eels.
Evans and Co owner Rupert Evans said: “It is much more in tune to the way the estuary works.
“Its construction would mean far less road traffic because of rail connections, and would require less material and cost significantly less than other tidal options or nuclear power.
“It is a compromise which works, it is considerably more efficient than tidal stream turbines but does not have the environmental impact that great monolithic barrages have.”
RSPB conservation director Mark Avery said: “The Government must crack the problem of how to use the Severn’s tidal power without harming its wildlife.
“We already know a Cardiff-Weston barrage would cost far more than almost any other form of green energy and seriously damage sites protected by law.
“A tidal reef could reign in that damage, cost the taxpayer much less, and be built more quickly.”
Professor Rod Rainey, who prepared the report for the RSPB, said: “We believe this scheme could be more powerful but less costly than other plans being put forward, particularly the Cardiff to Weston barrage.”
The Government and the Welsh Assembly began a feasibility study into harnessing the estuary’s tidal power in January, and consultation is expected to begin next year on which projects should be shortlist.
Ten schemes are being looked at, which include conventional barrages, tidal fences, tidal lagoons, and a tidal reef.
A group of 10 environmental organisations has been opposing the idea of a barrage because they believe renewable energy could be generated more cheaply using other technology.

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