Sinking wind turbines may cost 50m [pounds sterling].
Solutions are being looked at to stop offshore wind turbines sinking into the sea. Repairs could cost energy firms millions.
Dong Energy is one of many firms whose turbines are affected by a design flaw. It is preparing to look at solutions that could cost the firm 12 million [pounds sterling].
Dong Energy said the design flaw affects the connection between the turbine and its steel monopole foundations. An overlap of 6m exists between the two sections of the tower, with a gap of 45-90mm. The gap is filled with a concrete that acts like a glue, called a grouted connection.
Dong Energy said: "Small cracks in this grout make the transition piece slide down up to 25mm. This is a problem right across the industry."
At the Egmond aan Zee windfarm off the Netherlands coast, owned by Dong, cracks have started to appear in the concrete, causing turbines to slide down their steel monopile foundations and sink. The cracks are appearing because the towers have been moving back and forth in the wind for years.
The turbines at Egmond aan Zee are reported to have moved by a few centimetres from their original position.
Dong Energy has said that its windfarms at Gunfleet Sands, off the Essex coast, and Burbo Bank in Liverpool Bay have also been affected. The company has said it is looking at three possible solutions.
Trade association RenewableUK has started an investigation into the problem. It said that almost all of the UK's 336 offshore turbines could be affected, which could cost the industry 50 million [pounds sterling].
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|Publication:||Professional Engineering Magazine|
|Date:||Apr 21, 2010|
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