Suction bucket foundation. (Photo credit: NGI)

Sixty suction buckets have been pumped in place as foundation for 20 wind turbines in Ørsted’s new wind farm, Borkum Riffgrund 2. In June 2018, a team of specialists from Framo, the Norwegian Geotechnical Institute (NGI) and GeoSea installed the first of the 20 suction bucket jackets at the offshore wind farm. After periods of storm and high waves, the foundations of all 20 wind turbines were safely pumped into the seabed, with the final jacket foundation installed on July 30. The full commissioning of the wind farm is planned for early 2019.

Framo is a sub-contractor to NGI in the installation of the 20 offshore wind turbines. NGI and Framo have collaborated on the installation of offshore anchoring and foundation elements using suction/vacuum since the 1990s.The technology of suction and bucket foundation has been used to secure and safely anchor platforms and offshore installations around the world. Now, larger wind farms are being built with this technology. The foundation is installed by pumping water out of the buckets. This creates a suction/vacuum, which presses the buckets into the seabed.

The windfarm Borkum Riffgrund 2 is located 54 km off the coast of Lower Saxony in the German North Sea. In the installation of the 56 wind turbines, 20 will use the suction bucket technology as foundation, and 36 will be supported using monopiles. The three-legged foundations measure more than 50 m in height and weigh 950 t each. When the 8.5 megawatt giant turimages are in place, they will rise 109 m above sea level and have a wing span of 164 m. —Framo AS