Potential for development in offshore foundations

Wednesday, 29 August, 2012 - 14:45

New concepts for the foundations of offshore wind power systems could improve the energy payback time of the turbines by 100 %. This is the result of a study by Cambridge University.

Jim Platts of the Institute for Manufacturing (IfM) believes that the wind power industry could achieve significantly better payback times if instead of the current steel foundations it used guyed composite towers held in place using steel cables. A preliminary study by the IfM finds that it is possible to halve the amortization time in this way.

For onshore systems the energy balance is around 40:1. At 15:1, that of offshore systems is significantly worse. This is largely due to the offshore foundations, which require up to four times more concrete and steel than foundations onshore, according to the results of the study. "When you look at offshore wind turbines you see a series of slim structures – what you don’t see are the far heavier supporting structures below the surface that they slot into," says Platts. "We urgently need to reduce the high levels of energy embedded in offshore wind turbines, which make them both ineffective in energy payback and costly in financial terms. We can do this fairly easily if we invest in more innovative methods for making and installing the towers and the foundations that support them", he says.

Besides the weight disadvantages, Platts also points out the poor material qualities of steel. In contrast to composites, it is prone to corrosion and fatigue. The question is whether materials other than steel would not be better adapted. "The answer is yes: we can use composites for towers just as we do for blades. They are lighter, stronger, corrosion-free and more resilient than steel." If these lighter towers were anchored with steel cables, even more could be saved on the foundations. The study concludes that an energy balance of 25:1 could be achieved.

Katharina Garus

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