Connecting offshore wind energy to the grid

In addition to onshore wind energy, the use of offshore wind energy is another key element of the German government's energy and climate policy. Thanks to the constant and reliably high wind speeds at sea, offshore wind energy has an important role to play in the energy transition.

In Germany, suitable sites for the use of offshore wind energy are mainly to be found in the "exclusive economic zone", i.e. beyond the 12 nautical mile zone and, compared with other countries, well away from the coast. This gives consideration to the various other uses of the North and Baltic Seas, especially nature conservation, such as protection of the Wattenmeer world natural heritage site, or shipping and fisheries.

Offshore grid connections are needed to transport the wind energy generated in the North and Baltic Seas to the consumers. These connections link up the offshore wind energy installations with onshore connection points, from where the electricity is transported via the onshore grid. Due to the distance of the offshore wind energy installations from the coast, the grid connection is a technical, financial and logistical challenge. There is thus a need for close coordination between the design of a wind farm and the related grid connection so that the work can be synchronised and the financial risks minimised. Alternating current is used to transport the electricity generated by the Baltic wind farms. Due to the significantly greater distances in the North Sea, high-voltage direct current (HVDC) transmission lines of up to 320 kV are mainly used there.

The question of which offshore connection lines are to be constructed in the coming years is answered every two years in the offshore grid development plan, which the Federal Network Agency generally confirms in tandem with the onshore grid development plan. On this basis, the transmission system operators responsible for building the connection then undertake the necessary work.