Key SuedLink power transmission line reaches "milestone" with Elbe River crossing

One of Germany’s most important energy infrastructure projects, the SuedLink electricity transmission line, has taken an important step towards its completion by finishing a five-kilometre underground stretch crossing the Elbe River near the northern city of Hamburg. The tunnel connecting the states of Schleswig-Holstein and Lower Saxony is “one of the technically most challenging sections” of the transmission line, according to operator Tennet. 

Once completed, SuedLink will span over 700 kilometres and supply industry centres and households in southern Germany with electricity from the windy coastal states in the north. Up to ten million households will be able to use power supplied through the transmission line, which is seen as crucial for Germany’s energy transition and decarbonisation targets. 

Schleswig-Holstein’s state premier, Daniel Günther, called the Elbe River crossing “a milestone” for the project. SuedLink will help ease the country’s grid congestion challenges and ensure that much less renewable electricity will need to be curtailed to avoid overload in the future, he said. 

The SuedLink line has been under construction since 2023. According to operator Tennet, which shares ownership with transmission grid operator TransnetBW, construction work is on schedule and should be finished by 2028. The project initially was supposed to start in 2016 and be completed by 2022 but was held up for years due to political changes to construction priorities and protests by state governments and citizen groups against the transmission line’s planned route.

The expansion of Germany’s power grid to allow for the integration of the country’s growing renewable power capacity is one of the energy transition’s greatest challenges. As scattered wind and solar power installations with variable output replace centralised and controllable fossil power plants, grid infrastructure is becoming more complex and requires more flexible load management to keep it stable. 

Slow expansion of grid infrastructure has been an obstacle to the energy transition for years. Germany's current government is working on reforms that could slow renewable power expansion in regions with lacking grid capacity, an approach that has been criticised for failing to address slow grid buildout as the problem’s root cause.