onsdag 28 januari 2009

Severn barrage - boon or bane?


Severn estuary and bridges
Originally uploaded by net_efekt

The proposal to construct a Severn barrage to generate tidal power has come up for active consideration again. If it works as intended it will generate a significant proportion of Britain's electricity. But there are many questions to be asked. What of its effect on wildlife? How long will it take to pay back the cost of construction? What is the overall energy balance, when the embodied energy in the structure is taken into account? What will be its effects on water flows? How much dredging will it need to keep it free of silt? How useful is the electricity, bearing in mind that tidal flows are small for 8 hours in 24 and that peak flows vary according to the monthly lunar cycle. I hope someone will ask these searching questions.

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