March 16 - Research into wind turbine and monopile design plays a key role in identifying technologies and techniques that reduce build times and lower costs for the offshore wind energy industry - music to the ears of project logisticians serving the sec
At the close of 2015, wind energy majors RWE Innogy, Bilfinger Offshore, DONG Energy, EnBW, E.ON and Vattenfall, joined forces to pioneer a new vibratory pile installation method.
The goal was to identify if vibratory piling offers faster and more environmentally friendly method of installing steel foundations for offshore wind farms, in comparison to conventional impact hammering.
At an onshore test area near Cuxhaven, Germany, three steel piles were vibrated into saturated, sandy soil, while three piles were hammered conventionally.
The 4.3 m diameter monopiles were manufactured at the Steelwind Nordenham fabrication facility, the hammer was supplied by IHC Hydrohammer and the vibrator was supplied by PVE Dieseko. Technical University Braunschweig was responsible for data capture, including installation times and noise emissions, alongside technical experts, certification and regulatory authorities.
The piles were left in the ground for four months before undergoing static load testing, which examined how the piles behave when subjected to the kind of lateral load that is typical in offshore conditions.
The test identified that vibratory installation significantly reduced peak noise emissions and was up to ten times faster than impact piling. Furthermore, if during the installation process various parameters, such as vibratory frequencies or pile design, are controlled, similar lateral load-bearing capacities to hammered piles could be achieved.
Jan Matthiesen, director of innovation at the Carbon Trust, championed the positive results of the trial: "Finding innovative methods to reduce the cost of installation will help to bring down the cost of offshore wind, making it competitive with conventional energy sources. The project results not only demonstrate that vibro techniques could be a viable method for piling, but also evidence of what can be achieved through industry collaboration."
The research project was undertaken as part of the Carbon Trust Offshore Wind Accelerator. "Throughout the project we have collected a lot of important data, that can now be used to further develop the technology to bring it offshore", explained Ben Matlock from RWE Innogy.