Fraunhofer IWES to Test Soil in German Offshore Wind Zones

The German Federal Maritime and Hydrographic Agency (BSH) has selected Fraunhofer IWES, among others, to conduct the preliminary assessment of soil conditions in the first bidding round for new offshore wind farm zones in the North and Baltic Sea.

Fraunhofer IWES said it will conduct multichannel seismic measuring, which, in combination with isolated findings from geological drilling and cone penetration tests, makes it possible to create an extensive overall picture of the seabed, and will compile 3D seabed models based on geophysical data.

The results are expected to provide valuable information for the wind turbine foundations, the German research center said, adding that the method also offers numerous advantages for the re-dimensioning of planned wind farms.

If a larger MW class is selected, resulting in fewer turbines at changed positions, this can in some cases be implemented without follow-up surveys if high-quality and extensive data were collected at the start of the planning work, the center said.

According to Fraunhofer IWES, the methodology has been optimized for use in water depths of less than 100 meters, while the signal characteristics combined with a digital, highly sensitive multichannel registration unit (streamer) ensure the penetration of the acoustic signal to the intended foundation depth of the wind turbines and its reception.

The geophysical survey is scheduled for September, while the measurement campaign may take up to several weeks depending on the size of the area to be surveyed.

Knowledge of the soil conditions is important when planning and developing offshore wind farms since the information can be used as a basis when selecting and sizing the support structures for wind turbines, Fraunhofer IWES said, adding that data relating to the marine environment, the subsoil, and the wind and oceanographic conditions allow bidders to assess the construction costs and expected return more accurately.

In 2017, the German Offshore Wind Energy Act (WindSeeG) specified that the BSH must employ a tendering procedure for the awarding of exploratory work.

In accordance with the WindSeeG, preliminary assessment of soil conditions must be performed before contracts can be awarded for new offshore wind farm clusters in the North and Baltic Sea.