21GW German North Sea offshore network plan unveiled

Regulator proposes standards for DC cables

The second draft of Germany's offshore network plan (ONP) for the North Sea region, and an accompanying environmental impact report, are now available for public scrutiny. The draft ONP reflects the country's target for 25GW of offshore wind power to be installed in the North and the Baltic Seas by 2030. The BSH has assumed 21GW can be built in the North Sea with the remaining 4GW earmarked for the Baltic - for which a separate draft ONP is being prepared - as well as a few nearshore projects.

Responses to the draft will be accepted by the Federal Maritime and Hydrographic Agency (BSH) until 29 November and a public hearing will take place on 30 October in Hamburg.

A revision of Germany's energy act, which took effect last January, requires the BSH to produce an ONP every year, in cooperation with Germany’s federal energy regulator, the federal office for nature protection and coastal federal states.

Amongst other issues, the draft North Sea ONP identifies offshore wind projects suitable for bundled cable connection to shore, dividing them into 13 clusters. It also proposes sites for offshore substations, routes for direct current (DC) transmission cables to shore, and routes for cables connecting wind farms to substations.

Crucially, the ONP also proposes technical parameters that would allow standardisation of the offshore grid, such as a standard DC cable capacity of 900MW, a converter platform DC voltage of +/- 320kV and installation of substations in "mother-daughter" constellations, with platforms connected via bridging cable. The aim here is that if one platform or cable to shore fails the other can transmit at least some capacity to the land-based grid.