Quick Guide Measurement of Offshore Site Conditions

The greatest challenge in the harvesting of wind energy at sea is the extremely difficult environmental conditions. The wind there blows very persistently and reaches high speeds, while the harsh environmental conditions also mean the materials are subjected to special loads and render work deployments more difficult. Therefore, wind, seabed, and current measurement campaigns need to deliver extremely precise results and be performed with robust equipment.

 

Planning security for improved control of costs
The energy yields expected from a wind turbine/farm are balanced against the material costs for the turbines, erection and operation. As such, if the wind yield cannot be measured precisely, it represents a considerable risk for the economic success of the project and this is reflected in the financing costs. Failure to assess design parameters for the foundations and support structures precisely can result in increased costs for high calculation buffers in the safety factors. The employment of precisely  functioning measuring technology optimized for offshore use can reduce uncertainties considerably in combination with model calculations.

 

Wind, waves, currents
The Fraunhofer IWES wind LiDAR buoy is a LiDAR wind measurement device integrated in a sea buoy. The compact design, a robust, autonomous power supply system, and efficient data processing and communication ensure reliable and flexible offshore wind-measuring campaigns at minimal costs. The correctional algorithm developed by Fraunhofer IWES, which factors the buoy’s own movements out of the measurement data, guarantees high accuracy comparable with offshore mast measurements. The waves and current are recorded by the buoy in parallel. The service offering is rounded off by the modeling of the atmospheric flows and their interaction with wind turbines and wind farms.

 

Assessment of soil conditions
In cooperation with the University of Bremen, a geophysical site exploration method tailored to the special requirements of seabed exploration for offshore wind farms is currently under development. The use of digital multichannel seismics makes it possible to achieve signal penetration of up to 50 meters into the seabed – a considerable advantage compared with standard procedures. The high-resolution data also reproduce even the most complex of structures very precisely and document even obliquely running strata. This is of decisive importance for the assessment of soil conditions for a planned wind farm.

The improved geophysical site exploration permits significant cost savings during site investigation. The procedure has already proven itself in the field on multiple occasions in the North and Baltic Seas.