The SBJ foundation, designed by NGI and Ramboll is fabricated by Bladt Industries, Aalborg and transported to the Borkum Riffgrund 1 wind park for installation by Pacific Orca.
Until now, most offshore wind turbines are founded on monopiles. DONG Energy has installed the first jacket with suction buckets as a proof-of-concept full-scale prototype, to be tested and monitored over several years. The SBJ technology, previously used for offshore oil and gas platform foundations, has several economic as well as environmental advantages.
Ramboll has performed the design of both primary and secondary steel for the wind turbine foundation and buckets, working in close cooperation with the Norwegian Geotechnical Institute (NGI), who has delivered the geotechnical design. The cooperation between DONG Energy and the two experienced consultants has focused on establishing foundation loads and corresponding soil stiffnesses, which are mutually dependent. This is carried out to assess the short and long term global interaction between jacket and soil, and to determine the local soil/bucket interaction to ensure that the strong suction pressure for installation can be safely applied.
NGI performed laboratory tests of the soils to provide necessary data for structural and geotechnical analyses for the design of the SBJ foundation. Furthermore, NGI has also designed and successfully installed instrumentation for overall monitoring of the prototype, which includes 100 instruments, 7 km of cables and a data collection system. The British based Carbon Trust Offshore Wind Accelerator program including DONG Energy and the five other developers Statoil, Statkraft, E.ON, Scottish Power and Mainstream supports the prototype with MNOK 60.