North Sea Link

Before the cable reached the converter station at Kvilldal, it had to get through a mountain. Engineers drilled a 2.3 km tunnel from the fjord to the lake Suldalsvatnet, pulled the cable through, and then floated it across the lake to the Kvilldal side. So a North Sea cable ends with a lake crossing.

The link joins Kvilldal in Suldal Municipality with Cambois, near Blyth in Northumberland, over 720 km. Its purpose is a trade between two very different systems: Norway’s reservoir hydropower can be held back or released at will, while Britain’s growing wind fleet produces in surges. The cable lets each side buy when the other has a surplus.

It took a long time to start. A 1,200 MW version was first proposed in 2003 and later shelved. Statnett and National Grid announced a feasibility study in October 2009, took the construction decision in March 2015, and declared the project complete on 8 June 2021. Operation began on 1 October 2021, as the North Sea Link article records. The cost was about €2 billion.

Capacity arrived in steps. At first the link ran at a maximum of 700 MW, half its rating, then at 1 GW. It switched from monopole to bipole operation in January 2022, reached 1,300 MW by April 2023 and the full 1,400 MW by June 2023. Hitachi Energy, which supplied the converters, gives the ±515 kV rating; Prysmian and Nexans made the cable.

Ofgem’s analysis put the value over the 25-year regulatory period at around £490 million for the UK and around £330 million for Norway. On those estimates the British side gains more, though both come out ahead.

For a Norwegian comparison, see NordLink, which went into service the same year towards Germany.