Offshore windfarms look to ‘suction buckets’ for easier installation

UK windfarm developers are to be given access to new technology that could make it easier to erect offshore turbines.

The Carbon Trust has awarded Danish firm Dong Energy £6m to trial a method of installing turbine foundations without hammering them deep into the seabed, in return for making the test data available to other offshore developers.

The “suction bucket jacket” technology, adapted from the oil and gas industry, uses pressurised chambers to drive the foundation 7m into the seabed and hold it in place, rather than hammering the pile to depths of up to 40m into the soil.

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The technique uses on a three-legged jacket structure stood on three giant “buckets”. Once the jacket has been lowered onto the sea bed, pumps are used to create a pressure difference inside each bucket and this, combined with the weight of the structure, forces it into the soil.

‘You have a complete structure – it’s only one installation – so the buckets are an integrated part of the foundation,’ Dong Energy project manager Jonas Wittrup-Jensen, told The Engineer.

‘It does not need to go as deep as the piles and also the pumps are each driven by two 30kW motors so the noise is insignificant, whereas piling generates a high amount of noise.’

Asked about the relative cost of the new installation method, Jensen said: ‘It is competitive and we do it as part of our aim to reduce our cost of energy by 35 to 40 per cent.’

Under the Carbon Trust’s Offshore Wind Accelerator (OWA) project, five other companies including ScottishPower and E.ON will receive access to data from the trial in German waters in order to evaluate the potential for using the technology in the UK.

‘The benefit of the technology only really comes through if the supply chain picks it up,’ said the Carbon Trust’s director of innovation, Jan Matthiesen. ‘If you can demonstrate it to the market it’s much more attractive to the supply chain.’