Monopile 'vibro-driving' set for trial

A RWE-led group of wind farm developers is about to begin road-testing a new cost- and noise-reducing installation technique that uses vibration rather than high-impact hammers to pile-in large offshore monopiles.

The €6m ($8.3m) project, part of UK government-industry body the Carbon Trust’s Offshore Wind Accelerator (OWA) scheme, will see a trio of “vibro-driven” monopiles benchmarked against three driven in with conventional hydraulic hammering at an onshore demonstration project near Cuxhaven, on the German North Sea.

The pilot, which gets underway next month, aims to show the lateral load capacity of full-depth vibration-installed piles in sandy seabeds is as robust as that of hammered-in monopiles, while having lower noise levels, being quicker and more cost-effective, and causing less fatigue and stress to the foundations.

“The use of vibration piling has been predicted, and partly demonstrated in selected offshore applications, to decrease the piling time by more than half of that required for impact hammer driving,” states Carbon Trust senior manager Jan Matthiesen. “Innovations such as these can reduce costs significantly for the whole offshore wind industry.

“We hope [through the project] to achieve valuable insights in order to make vibration-driving commercially feasible.”

The piles, being manufactured by Steelwind Nordenham, will measure 21-metres in length and 4.3-metres in diameter. Bilfinger Construction is responsible for installation and testing of the monopiles. Test results are expected by the end of the year.

RWE Innogy, partnered with Dong, EnBW, E.On and Vattenfall, says it could look at vibro-piling to improve the design of offshore wind farms such as its planned Nordsee One project, located about 40 kilometres north of the German island of Juist.