Severn Barrage - No match for electricity generating tidal lagoons

Electricity generating tidal lagoons would be far preferable both economically and environmentally to the proposed Severn Barrage says Friends of the Earth Cymru in a report published today (1). The report compares tidal lagoons in the Severn Estuary with the long proposed Severn Barrage scheme (2). The group says tidal lagoons, a new concept in renewable electricity generation, could also make a significant early contribution to reducing the UK's global warming emissions.

The report concludes that several large lagoons enclosing the optimum shallow areas of the Severn Estuary, equivalent to a square of 11 miles by 11 miles, would:

• provide 6% of UK electricity demand (2.75 GW average) which is as much as three to four nuclear power stations (3)
• generate 30% more electricity annually from the Estuary at less than half the kWhr output cost of the Barrage (4)
• impound an area 40% smaller than the Barrage and would not impede shipping to Bristol, Newport and other Severn ports
• be sited about a mile or so offshore so avoiding the ecologically sensitive intertidal areas of the Estuary

Tidal lagoons are a new and largely unforeseen electricity generating concept and the developer Tidal Electric Ltd says that studies to date indicate that lagoons would be commercially attractive. Last year AEA Technology (5) reported that such rock-wall impoundments are 'technically-feasible', 'environmentally-neutral', and 'economically-profitable'. Now a team of engineers lead by WS Atkins and ABPmer is designing a 30 MW offshore tidal power project for Swansea Bay, in the western part of the Severn Estuary (6). The team expects to report soon on the economic and technical feasibility of this specific project, including output, construction techniques, and environmental issues.

If a scheme is built in Swansea Bay it would be the world's first. The Severn Estuary is prime location for lagoons as it has the second highest tidal range globally. Other possible UK sites are in Liverpool Bay (area to the north of Rhyl) and the Thames Estuary. The likely sites are to varying degrees ecologically sensitive and the overall effects on birds and other species, some of which could be positive, would have a large influence on where lagoons could be sited.

Neil Crumpton, energy spokesperson for Friends of the Earth Cymru said:

" Tidal lagoons could make a significant and timely contribution to the UK's energy and climate protection policies. Our initial assessment indicates that lagoons in the Severn Estuary would be far preferable to the Severn Barrage both economically and environmentally. If the WS Atkins study concludes that the cost of power is commercially attractive then the DTI and Welsh Assembly should take very serious interest and support site specific studies so that environmentally friendly schemes could be built sooner rather than later."

Peter Ullman of Tidal Electric Ltd said:

"We are pleased that AEA Technology has affirmed the general economic and mechanical practicality of our offshore tidal lagoon technology and that WS Atkins and ABPmer are advancing the Swansea Bay project. Our expectation is that the predictable nature of tidal power will be complementary to the less predictable renewables to the benefit of all renewables."

Friends of the Earth Cymru thinks that such is the potential scale of power generation the Government's renewable electricity target of 15% by 2015 could in due course be revised upwards if there is no significant additional cost to consumer bills. Such a target revision would protect the development of other renewable energy technologies and the additional capacity would calm current fears about Grid and energy security due to the decommissioning of ageing nuclear and coal plants.

Friends of the Earth Cymru is calling on the DTI, Welsh Assembly and other relevant agencies to carry out a Strategic Environmental Assessment (SEA) of the Estuary which would include possible lagoon locations, and provide any necessary support to assist in detailed site studies.

Notes

1) A Severn Barrage or Tidal Lagoons? - A Comparison

www.foe.co.uk/resource/briefings/ ¬
morglawdd_hafren_neu.pdf (PDF format) (Cymraeg)
www.foe.co.uk/resource/briefings/ ¬
severn_barrage_lagoons.pdf (PDF format) (English)

Tidal lagoons are large rock-walled impoundments built in shallow coastal waters where there is a high tidal range. Tidal water is trapped and released through electricity generating water turbines built within the walls which would look much like a typical harbour breakwater.

2) The Severn Barrage scheme as proposed by the Severn Power Tidal Group (STPG). This scheme featured in three out of four illustrative future UK energy scenarios which the Royal Commission on Environmental Pollution had envisaged in their 2000 energy report (Royal Commission on Environmental Pollution, 22nd Report 'Energy - The Changing Climate' 16th June 2000 www.rcep.org.uk/).

3) UK Electricity demand averages of 45 GW annually, an optimum area of lagoons in the Severn could average 2.75 GW

4) Tidal Electric Ltd estimate that the Unit price (for 1 kWhr) would be in the range 2.0 - 2.5 pence. This compares very favourably with the price estimates in the Government's Performance and Innovation Unit report 2002 which studied a range of renewable, fossil fuel and nuclear technologies (See Summary of Key Findings, Annex 6. www.number-10.gov.uk/su/energy/20.html).

5) AEA Technology is a major energy consultancy

6) WS Atkins is the UK's largest engineering firm and lead engineer for Tidal Electric Ltd's study, and ABPmer is the research arm of Associated British Ports which own numerous ports around the UK and who are conducting the coastal process modeling work.

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