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
Bornholm Energy Island takes next step with construction contract award
Energinet has awarded the contract for the buildings that will house key electrical infrastructure for Bornholm Energy Island in Denmark to Per Aarsleff A/S - a Danish contracting and infrastructure group with experience in large and complex construction projects. The award marks another important step in the joint Danish-German project developed by Energinet and 50Hertz.
The contract covers buildings for three converter stations in Denmark — one on Zealand and two on Bornholm — as well as the building for a new 400 kV high-voltage station on Bornholm. It also includes site preparation, access roads and related civil works around the station areas.
Bornholm Energy Island is being developed jointly by the two transmission system operators Energinet in Denmark and 50Hertz in Germany. The project will connect offshore wind power in the Baltic Sea with the electricity grids in Denmark and Germany and support a more integrated and resilient European energy system.
With the selection of Aarsleff, the project moves further towards the construction phase. The coming period will focus on detailed design and planning before construction is expected to begin in 2027.
Once completed, the infrastructure will help collect and transmit large amounts of renewable electricity from future offshore wind farms near Bornholm to consumers in Denmark and Germany.
Visualisation: C.F. Møller Architects
Architecture and landscape integration on Bornholm: The contractor’s proposal uses materials, colours and landscaping that reference Bornholm’s geology and landscape for the projects main station on Bornholm. Concrete bases, natural stone façades and earthy tones give the buildings a calm architectural expression, while planting, terrain modelling and pathways help screen the facility and integrate it into the surrounding landscape in line with the local plan.
Buildings for the key facilities on Bornholm: The visualisation shows the largest buildings to be constructed on Bornholm: four converter halls and a GIS building. The area marked “Construction Site Facilities and Laydown for BEI” on the map is reserved for future DC breakers. They are not part of the current project, but they have been included in the planning, as they are essential for future connections.
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.