50Hertz and Energinet have joined forces to fully harvest the offshore wind potential held in the Baltic Sea, power the green transition in Germany and Denmark, and spearhead a new idea for connecting offshore wind farms across borders: the Bornholm Energy Island (BEI) project. This innovative and visionary project will connect multiple wind farms together via a single hub and transport the green electricity that they generate to consumers in both countries while providing transmission capacity for cross-border trading.
The green future of offshore wind hubs and hybrid connections
BORNHOLM ENERGY ISLAND
VISION & TECHNICAL FEATURES
Together, 50Hertz and Energinet want to establish a power hub on the island of Bornholm that is able to provide electricity to consumers in either country, depending on the market and demand in Germany, Denmark and Europe more widely. Electricity generated by the wind farms located off the coast of the island will be centralised at this hub and then converted into high-voltage direct current (HVDC) and transported via 525 kV HVDC sea and land cable systems to onshore substations in Zealand (in Denmark) and Mecklenburg-Western Pomerania (in Germany). In addition, the BEI project will enable the local community on the island to be connected to both Zealand and continental Europe.
Cooperation between countries is the way forward
50Hertz and Energinet are pioneering innovators. BEI will pave the way to a future in which offshore wind energy is no longer harvested by individual countries alone. Instead, in line with the offshore wind potential held by different countries and electricity demand in these, two or more countries will cooperate to efficiently integrate the green electricity generated by offshore wind farms into their energy systems.
We at 50Hertz and Energinet hold a significant amount of expertise in feeding electricity from offshore wind farms into our power grids. The Kriegers Flak - Combined Grid Solution (KF CGS), our joint project which has been fully operational since 2021, laid the foundations for making hybrid interconnectors a reality in both the Baltic Sea and the North Sea. We will continue to use our know-how to implement ever-evolving, more complex and more efficient on- and offshore energy hubs.
NEWS & EVENTS
Environmental permit granted for Bornholm Energy Island’s onshore facilities in Denmark
After a thorough environmental assessment and several rounds of public consultation between 2022 and 2025, the Bornholm Energy Island project has received the environmental permit for the onshore and offshore facilities and cables. This sets the framework for construction, ensuring it’s carried out with the greatest possible care for people, nature, and the environment. The permit covers onshore installations on both Bornholm and Zealand, as well as the Danish cable connection between the two.
The environmental assessment process has been extensive, with the documentation including an environmental report and several sub-reports—adding up to more than 4,300 pages. These documents detail the potential impacts and how they can be mitigated. Throughout the process, multiple public consultation rounds and information meetings on Bornholm and Zealand took place, inviting citizens, municipalities, and organizations to share questions, concerns, and local insights, which helped shape the final documentation.
As for next steps, although the environmental permit is now in place, major construction won’t start immediately. Preparatory activities—such as archaeological investigations, technical studies, landowner agreements, detailed planning, and tendering—still need to be completed, all in line with the permit’s requirements.
The full Bornholm Energy Island project, including the offshore wind farms, is expected to be commissioned in 2036. The cable between Bornholm and Germany (owned by 50Hertz) is undergoing a separate environmental process in both Denmark and Germany.
Picture: Elia Group
Energinet is an independent public enterprise owned by the Danish Ministry of Climate, Energy and Utilities. Energinet owns, operates and develops the transmission systems for electricity and gas in Denmark. Energinet’s purpose is to own, operate and develop the overall energy infrastructure and manage related tasks, thus contributing to the development of a climate-neutral energy supply.
50Hertz operates the electricity transmission system in the north and east of Germany, which it expands as needed for the energy transition. Within these regions, 50Hertz and its around 2,100 employees ensure that 18 million people are supplied with electricity around the clock. 50Hertz is a forerunner in the field of secure integration of renewable energy. In our grid area, we want to integrate 100 percent renewable energies securely into the grid and system by 2032 - calculated over the year. The shareholders of 50Hertz are the Belgian holding Elia Group (80 percent), which is listed on the stock exchange, and the KfW bank group with 20 percent.