World's First Hybrid Interconnector Inaugurated

CGS is a technological innovation that can serve as an example for future offshore power grids, says 50Hertz. The grid connections of German wind farms Baltic 1 and 2, which are operated by 50Hertz, as well as the grid connection to Danish wind farm Kriegers Flak, that is currently under construction, are also used as an interconnector. Two submarine cables of only 25 km length with a capacity of 200 megawatts (MW) each, laid between the offshore substations of Baltic 2 and Kriegers Flak, bring both grid connection systems together.

The pioneering work done by this project can also benefit other European projects. Stefan Kapferer, CEO of 50Hertz: "The CGS is an essential puzzle piece of our strategy to cover 100 percent of the electricity demand in our grid area, over the course of a year, with renewable energy by 2032. In addition, the project shows the high significance of the European Baltic area for the energy sector. This importance is also reflected in the Baltic Sea Offshore Wind Declaration, which was signed by the neighbouring states in late September."

As the transmission grids of eastern Denmark and Germany are not synchronous, the construction of a double converter (back-to-back converter) at the Bentwisch substation near Rostock was necessary for this interconnector. Through the converter, the arriving alternating current (AC) is converted into direct current (DC) and immediately into alternating current again. This procedure is the only possibility to ensure a smooth flow of electricity from Denmark to Germany and vice versa.

On the Danish side, too, the project is of central importance for the country's aspired climate neutrality. The Kriegers Flak wind farm will supply electricity to approx. 600,000 households when commissioned next year. It has a capacity of 600 MW and will be the largest wind farm in Denmark.

Thomas Egebo, CEO of Energinet: "The groundbreaking project also delivers an important building block for decarbonizing the rest of the society. Wind and PV must in the near future replace petrol in our cars, oil, coal and gas in our private and district heating. And power from wind and solar will in the long run be the main ingredient in production of green hydrogen, green gasses, jetfuels, for industry, shipping and aviation."

Elia Group, which includes 50Hertz, believes hybrid connections are necessary to achieve the goals of the European Green Deal. In view of the enormous demand for electricity necessary for the decarbonisation of our societies, Europe must exploit all potentials for electricity generation from renewable energies and harvest this electricity, in some cases far from the coasts of the Member States.

Chris Peeters, CEO of Elia Group: "The hybrid technology increases the efficiency of your investment: when there is no wind, the cable can be used as an interconnector. In this way, the Combined Grid Solution project also links the flexibility of two energy markets and gives access to renewables at the lowest cost. This is of vital importance to energy-intensive industries."