A new study by Fraunhofer IWES finds that connecting offshore wind farms in the Danish and Swedish exclusive economic zones directly to the German electricity grid could significantly improve system performance. The analysis assesses the economic and technical effects of cross-border offshore wind planning compared with a purely national expansion pathway. It considers electricity output, system costs including grid expansion, wake effects and implications for security of supply.
Compared with expansion limited to German North Sea and Baltic Sea waters, system costs could be reduced by several billion euros while electricity generation could increase by up to 13%. The study compares scenarios in which Germany reaches its target of 70 GW of offshore wind capacity by 2045 solely within its exclusive economic zone with scenarios in which up to 20 GW are built in neighbouring countries but connected directly to the German grid. These capacities would still count towards the national expansion target.
Spatial dispersion of offshore wind farms reduces congestion in German waters and lowers wake effects in the German Bight. This leads to higher full-load hours and increased electricity generation across the North Sea region. At the same time, overall system costs, including grid connection and expansion, decline.
According to the study, radial connections of offshore wind farms in neighbouring countries offer several system advantages. Danish offshore wind zones provide strong wind resources, and their integration into the German grid increases the average full-load hours of Germany’s offshore wind portfolio. Improved wind conditions also reduce specific costs per megawatt-hour. The analysis indicates up to 13% higher electricity output alongside cost reductions of up to 11% per megawatt-hour, including grid connection.
A wider geographical distribution of offshore wind generation in the North Sea and Baltic Sea also strengthens security of supply and supports additional generation during periods of lower wind in Germany.
The findings highlight the strategic importance of closer cooperation among North Sea countries. Cross-border planning can enable a more cost-efficient and resilient expansion of offshore wind capacity. The study concludes that bilateral agreements would be required to allow the use of offshore wind areas in Danish and Swedish exclusive economic zones while ensuring that these capacities continue to count towards Germany’s expansion targets.
The study, titled International Optimisation of Full Load Hours in the German Bight – Cross-Border Radials, was conducted by Fraunhofer IWES on behalf of Bundesverband Windenergie Offshore and Bundesverband der Energie- und Wasserwirtschaft.
