Fraunhofer Institute for Wind Energy and Energy System Technology IWES Northwest has applied its multi-channel seismic system for surveys that allowed the construction of the Arkona offshore wind project to be on time despite changes to the wind farm design.
The modified project plan incorporated 60 turbines instead of 80 because of the switch to the larger 6MW class.
By the time the decision to install the larger class of turbine was taken, the results of 100 drilling operations and 13 pressure sounding tests for the wind farm were already in. This meant that some of the drilling and sounding locations no longer coincided with the new turbine locations and that most of the existing exploration profiles could not be directly applied to the new locations.
The developer decided to procure reliable data to describe the new sites that had been selected for confirmation by the German Maritime and Hydrographic Agency (BSH).
Seismic surveys using the multi-channel seismic system have allowed looking at deeper layers, which was important, as the support structure of a wind turbine penetrates 50 meters into the seabed. Experts at Fraunhofer IWES created a 3D model of the seabed based on these seismic data, which led to getting the design of the wind farm approved.
The properties of the existing drilling profiles were applied to the new turbine locations for which the seismic survey had been conducted. The subsequently certified method satisfied the technical experts at the BSH.
“The recognition by the BSH of the geotechnical survey method combining multichannel seismics and boreholes highlights the success of this project, which was overseen by a geotechnical expert and certifier. The completion of the final report in an optimal timeframe and without undue cost also shows the potential offered by the application of this innovative, complementary seismic surveying method,” said Martin Ros, Engineering Manager of the Arkona Construction Team, E.ON Climate & Renewables Services GmbH.