European offshore wind cooperation increases electricity yields and significantly reduces costs

On the occasion of the North Sea Summit in Hamburg, a new study by Fraunhofer IWES on behalf of the Federal Association of Offshore Wind Energy (BWO) and the Federal Association of Energy and Water Industries (BDEW) shows that if offshore wind farms in the Danish and Swedish Exclusive Economic Zone (EEZ) were to be connected directly to the German electricity grid, the system costs of offshore wind energy could be reduced by several billion euros compared to expansion exclusively in the German North Sea and Baltic Sea. At the same time, electricity yields could increase by up to 13 percent. Prerequisite for this is cross-border cooperation in utilisation of area and grid connection.

For the first time, the scientists from Fraunhofer IWES have comprehensively calculated the economic effects of cross-border offshore wind planning compared to a purely domestic expansion path. In addition to electricity yields, the system costs including grid expansion, shading effects and impact on security of supply are also analysed.

“The expansion of offshore wind energy is a central pillar of energy supply in Germany and Europe,” says Hans Sohn, Head of Policy and Communications at the BWO. “The study shows how the legally defined target of 70 gigawatts of offshore wind by 2045 can be achieved much more cost-effectively. Offshore wind farms in Denmark and Sweden that are directly connected to the German power grid – so-called radial connections – increase yields, reduce system costs and make the electricity system more robust.”

Cross-border planning increases efficiency

The study focuses on the comparison between a complete expansion of 70 gigawatts of offshore wind capacity within the German Exclusive Economic Zone (EEZ) and scenarios in which up to 20 gigawatts of this capacity is set up in neighbouring countries but directly connected to the German electricity grid. These capacities should continue to be counted towards the national expansion target.

This spatial equalisation reduces the concentration of offshore wind farms in the German EEZ. Shading effects in the German Bight decrease, leading to increased full load hours and greater electricity yields for all offshore wind farms in the North Sea region. At the same time, the economic costs of offshore wind expansion are reduced – including the costs of grid connection and grid expansion.

Higher full-load hours, lower costs, more security of supply

The study shows that radial connections of offshore wind farms to neighbouring countries offer several systemic advantages. The offshore wind zones in Denmark have particularly productive wind sites. Their connection to the German power grid increases the average full-usage hours of the “German” offshore wind portfolio.

Better wind conditions also lead to lower specific costs per megawatt hour generated. The analysis shows an up to 13 percent higher electricity yield with up to 11 percent lower costs (in euros per megawatt hour, including grid connection) at the same time.

Moreover, the broader geographical distribution of the wind yield in the North Sea and Baltic Sea strengthens security of supply and ensures additional feed-in during phases of weaker winds in Germany.

European cooperation as a strategic lever

From the BWO’s point of view, the results of the study underline the importance of closer and more binding cooperation between the countries bordering the North Sea. Cross-border planning opens up new scope for the cost-efficient, system-friendly and resilient expansion of offshore wind energy.

“The federal government already agreeing on this approach in its coalition agreement is a positive move,” says Hans Sohn. “The closer cooperation with the North Sea countries provided for in the agreement and the development of production-optimised spatial scenarios are taking things in exactly the right direction. The BWO expressly supports these efforts and hopes for constructive talks between the Federal Government and neighbouring countries in order to jointly leverage this potential.”

This will require bilateral agreements that make it possible to use offshore wind areas in the Danish and Swedish Exclusive Economic Zones, provided that they are not needed there, and to continue to count these capacities towards the German expansion target.

Background to the study

The study “International Optimization of Full Load Hours in the German Bight – Cross-Border Radials” was conducted by Fraunhofer IWES on behalf of BWO and BDEW. The short version of the Fraunhofer IWES study can be found here. The publication of the whole report is scheduled for February 2026.

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