NordLink

For almost a minute in September 2020, during testing, NordLink accidentally imported its full 1,400 MW into Norway. The surge shifted the frequency of the Nordic grid by 0.5 Hz, a large jolt, according to the NordLink article. It showed how much weight one cable carries between two synchronous areas.

Statnett’s own summary of the purpose is a single sentence: Norwegian hydropower and German wind energy complement each other. When German turbines produce more than the country can use, Norway can import and hold water back in its reservoirs; when the wind drops, the flow reverses.

The route has three parts. From the converter at Ertsmyra near Tonstad, in Sirdal, a 53 km overhead line on 140 towers crosses Norway to the coast. A 516 km submarine cable runs under the North Sea to the German shore at Büsum, and a 54 km land cable carries it to the converter station at Wilster in Schleswig-Holstein.

Statnett and E.ON Netz launched a feasibility study in 2008, and financing was decided in 2015. Trial operation began on 9 December 2020, the partners took the link over from the suppliers on 31 March 2021, and the opening ceremony was held on 27 May 2021, as Statnett announced. The owners are Statnett, TenneT and the German state bank KfW. Hitachi ABB Power Grids supplied the converters and Nexans and NKT the cables, and the total cost was estimated at €1.7 to 1.8 billion, about half of it paid by Statnett.

The cable is only as useful as the grids on either side. In November 2021 higher exports from Norway to the Continent led to a dispute with the Swedish system operator, which cut export capacity in half; more generally, grid limits on land frequently restrict what the cable can carry. The grid congestion guide explains the problem. Sources differ on the length (623 km or 625 km) and voltage (525 kV or 500 kV); the figures above follow Statnett and Hitachi Energy. Statnett expects the link to run for 40 years.