Opportunities and challenges in providing wind information for the German offshore wind auctions according to WindSeeG

The construction of offshore wind farms in the North Sea and Baltic Sea in Germany's Exclusive Economic Zone (EEZ) is crucial for the successful implementation of the energy transition. Since 2021, the Federal Network Agency has put potential sites out to tender every year. Therefore, detailed information on the wind conditions at the sites is essential for the bidders' energy yield calculations. The tender preparation is conducted in cooperation with the Federal Maritime and Hydrographic Agency (BSH) according to the Offshore Wind Energy Act (WindSeeG). The German Meteorological Service (DWD) supports the BSH in compiling the required wind information.

To assess the local wind conditions, an externally contracted one-year floating LiDAR measurement campaign is carried out for the potential site. This data is combined with the long-term in-situ measurements from the FINO1, FINO2 and FINO3 research platforms in the North Sea and Baltic Sea (https://www.fino-offshore.de/de/index.html). Additionally, the DWD provides corresponding model data and evaluation results of the COSMO-REA6 and ERA5 reanalyses. These data sets form the basis for the preparation of the comprehensive wind reports for the sites. All reports and the data are made publicly available to bidders by the BSH via the PINTA portal (https://pinta.bsh.de). The first two tendering processes have been successfully completed for three sites in the south-eastern North Sea (N-3.7, N-3.8, N-7.2) and for one site in the Baltic Sea (O-1.3) in September 2021 and September 2022, respectively. In 2023, a call for tender for sites N-3.5, N-3.6, N-6.6 and N-6.7, located in the North Sea, has been published and in 2024 for the North Sea sites N-9.1, N-9.2 and N-9.3.

 

A detailed investigation of the seasonal variability as well as an in-depth assessment of the current and historical wind conditions for the respective site is possible with the unique measurement and reanalysis data. The floating LiDAR wind measurements focus on the heights relevant for future wind turbine types and extend up to 250 m. The reanalyses are evaluated for the grid points closest to the sites and for the surrounding grid points. The data is validated using existing measurement data. Previous evaluations show a very good correlation, highlighting the added value of the reanalyses for determining the wind conditions at the sites. As future wind farms are planned for about 30 years, information on long-term variability is required. Long-term time series of geostrophic wind, derived from air pressure data from coastal stations from 1877 onwards enable an assessment of multi-decadal variations.

Future wind farms in the North Sea will be located even further off the coast. This will pose new challenges for the pre-investigations in all disciplines.