In April 2013 E.ON started preparations for constructing the Amrumbank West offshore wind farm. So-called scour protection is currently being installed north-west of Helgoland.
This comprises two layers of special sand bags on the seabed to prevent the sea current from washing away the sand around the foundations of the wind turbines, thus ensuring turbine stability. The sand bags are geotextile sand containers placed on the seabed. This new technology draws on experience gained in river engineering and coastal protection where this form of scour protection has already replaced traditional armour stones.
E.ON is a pioneer in the use of this innovative technology for offshore wind farms. Separating the scour protection from the installation of the foundations has significant logistical advantages and helps to further reduce the cost of offshore wind energy. E.ON’s aim is to reduce the construction and operating cost of offshore wind farms by 40 percent by 2015 so that this renewable energy source can make a cost-effective contribution to our energy supplies.
Together with Hanover University, E.ON first examined how sand bags react during the installation of the foundations. E.ON has a cooperation agreement with the Peter Madsen A/S shipyard from Denmark; during the last few months the latter has filled sand bags, each holding about 1m², on the Danish island of Rømø and is now starting to install them at the offshore site. The two layers cover an area having a diameter of 25m around the monopile foundations.
Amrumbank West is one of three offshore wind farms being built by E.ON in the North and Baltic Seas in the next two years. A total of 80 wind turbines are being erected from this autumn on an area of about 32km², which is the equivalent of over 4,700 soccer pitches. The state-of-the-art 3.6MW turbines will have a total capacity of 288MW and can thus supply up to 300,000 homes. This will reduce carbon dioxide emissions by more than 740,000t annually. Commissioning of Amrumbank West, which involves an investment of over one billion euros, is to be completed in mid-2015.
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Press release, May 29, 2013; Image: E.ON