Severn barrage will be reconsidered

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5 September 2012, Electricity

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The last proposal for a Severn Estuary tidal barrage was shortlisted to five potential projects and was examined at a cost of GBP4.3m only to be rejected in 2010, which caused the Labour minister Peter Hain to quit his shadow cabinet role to support the scheme. At first glance, the scheme looks like a great idea in an area with the greatest tidal ranges in the UK - up to 14 meters - and enough renewable energy to generate 5% of the UK's electricity for at least the next 120 years while cutting the UK's emissions by 1%. The scheme could create 20,000 jobs in construction and a further 30,000 jobs in activity around the barrage, but with previous proposals estimated to cost around GBP30bn and its location in an area of high environmental and social value, the costs of a tidal barrage scheme will be extremely high.

According to the 2010 feasibility study, the longevity of the scheme will bring the levelized costs of electricity generation down to between GBP110 and GBP170 per MWh for the different barrages within the previous proposal after the social costs and benefits are factored in. This compares to the levelized cost of offshore wind (GBP100 per MWh) and nuclear power (GBP40 per MWh). However, over an investment period of 40 years, the levelized costs of the barrages would be far greater, ranging from GBP320 to GBP520 per MWh.

The return on investment from the electricity generation over a 40-year investment period would not cover the construction costs of the scheme without significant government finance. Hain has stated that several sovereign wealth funds are willing to finance the project, given government support. A specialized feed-in tariff for a 25-30 year period would be needed alongside statements of government support to make the barrage attractive for investors, after which the barrage would continue to produce electricity at a low cost for the rest of its lifespan.

Of the previous proposals, the most economically attractive projects would also have the largest environmental impacts, and due to the nature of the area this trend is likely to continue. The Severn Estuary is home to a plethora of wildlife, and areas that would be threatened by the construction of tidal barrages include Special Protection Areas, Special Areas of Conservation, Sites of Special Scientific Interest, Scheduled Ancient Monuments, and Areas of Outstanding Natural Beauty. Over 70,000 birds winter in the area, and the estuary is a migratory pathway for aquatic species such as Atlantic salmon, which support inland industries.

The costs of mitigating the adverse effects of the previously proposed projects have made them unfeasible, and new proposals will have to take a different approach in their design as well as financing. The tidal range of 14 meters should not be overlooked as a significant source of renewable energy, but all future proposals will be balanced against alternative options, and judgments so far have deemed that there are better ways of generating clean electricity without causing such adverse effects. Future project proposals will have to have minimal environmental impacts and should include smaller scale lagoons, but the economic feasibility of such projects is less appealing to investors.

It will be interesting to see if the new proposals that may come under consideration will be able to drastically minimize environmental impacts and make the UK a better place for future generations, but it will be impossible to benefit all interested parties considering the complexity of the area. As a result, it is likely to be at least 10 years before the valuable renewable energy resources in the area may be exploited.

Source: Datamonitor

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