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Disagreement over Severn Estuary tidal projects

Environmental organisations say the shortlist of five potential tidal power schemes for the Severn Estuary announced earlier this year, is “seriously flawed” at the same time as the journal ICE Maritime Engineering say a Severn barrage would increase biodiversity and improve water quality.

The alliance of environmental organisations:

According to a report from engineers Atkins, commissioned by an alliance of environmental organisations, the shortlist for tidal power projects announced by the Department for Energy and Climate Change (DECC) was based on out of date calculations and criteria “weighted against more innovative and potentially more environmentally friendly projects.”

Atkins found that the consultant’s report used by the Government to compile the shortlist:

  • Contained calculations for the different tidal power schemes based on a 30-year-old study;
  • Seriously underestimated the amount of electricity that could be produced by more innovative and potentially more environmentally friendly tidal projects;
  • Could have underestimated the cost of large tidal power schemes – which Atkins calls environmentally destructive – such as the Cardiff-Weston barrage;
  • Failed to establish a fair basis for comparing the proposed schemes; and
  • Gave little weight to environmental impacts when considering the options.

Martin Harper, Head of Sustainable Development at the UK environmental and bird charity RSPB, said: “The Government doesn’t need to rush to judgement on this. If they do, there is a serious risk they will pick the wrong project. As this review shows, that could mean unnecessary damage to the environment, an oversized bill for the taxpayer and all for less electricity than is possible.”

The Severn Estuary has a 45 ft tidal range, is a Ramsar wetland site under international law and a Special Protection Area under European law.

Severn barrage could boost biodiversity

At the same time as environmental organisations criticise the shortlist, an article in the peer-reviewed journal Proceedings of the ICE – Maritime Engineering, is praising the suggested Severn Barrage tidal power scheme on the shortlist saying it could boost biodiversity and improve water quality.

The Cardiff-Weston Barrage would cross the Severn estuary from Brean Down, near Weston super Mare to Lavernock Point, near Cardiff. Its estimated capacity is over 8.6 GW and it could generate nearly 5% of UK electricity, according to DECC.

The article, written by Christian Retière, Director of the Laboratoire Maritime in France and Robert Kirby, UK marine consultant, looked at the ecological effects of the 42-year-old tidal power barrage at La Rance in Brittany, France, and applying the data to the Severn tidal barrage.

According to a statement issued by the Proceedings of the ICE – Maritime Engineering, “the report shows that the flora and fauna around the 750 m long Rance barrage is far richer and more abundant compared to equivalent adjacent areas; in some cases it has almost doubled. Although the Rance barrage lacks fish passes there is no evidence this had impaired the passage of any organisms; and water quality also remains unimpaired.

“The authors say they can conclude with certainty that the effects the barrage has had on wildlife – which they have dubbed the ‘Rance effect’ – will be replicated in the proposed UK counterpart between Cardiff and Westeon-sueper-Mare.”

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Wave and tidal energy



Greenheatman said

22 May 2009
I recently submitted a proposal that would harness the power of the Severn's Spring tides only and leave shipping and the Neap tided to come and go freely through the Cardiff - Weston barrage. The energy in the Neap tides is not required so the intertidal area available to the Severn's fauna remains unaffected for around 60% of the lunar month.
The idea is to provide Aberthaw B coal fired power station with over 12TWh(thermal) from just 17 Spring tides at or close to the new moon or full moon.

Aberthaw would be capable of generating over 4TWh of secure base load electricity annually without burning a kg of coal. A by-product from the process is billions of tonnes of desalinated water.

However, this proposal was rejected on the grounds that the application did not include schematics and a that there was not enough information on environmental impact! There will be practically zero impact - that was the reason there was no lengthy submission on that subject - The reason for the lack of schematics is that I assumed, wrongly, that the written word would be understood.

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