North Sea Link passes halfway point in Norway

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Construction of the North Sea Link, the world’s longest subsea power cable, has passed the halfway point following an operation to move the cable through a Norwegian lake.

North Sea Link
The platform held all the necessary equipment that is usually found on offshore cable laying vessels (Image: National Grid)

North Sea Link, a joint venture project between National Grid and Norwegian system operator Statnett, is a subsea cable that will connect the UK and Norwegian electricity grids. The €2bn project, National Grid’s fifth under water electricity cable, will connect British homes into Norway’s biggest hydro-dam.

Power sharing: building the world’s longest subsea electricity interconnector

Before being able to lay the cable in Norway, the team first had to tackle manoeuvring the cable through a lake, which cannot be accessed by the size of the vessel usually required for cable laying.

Instead, the team built their own custom-made floating platform over the course of 11 days, an operation in Suldalsvatnet that marks the start of the cable laying on the Norwegian side.

Working at depths of up to 210m, the laying of the 2.8km parallel subsea cables was executed from a 43m x 15m platform.

The equipment required to lay the cable was then installed on the platform, and within 12 hours, 150 tonnes of cable were loaded on board. The platform held all the necessary equipment that is usually found on offshore cable laying vessels.

In a statement, Nigel Williams, Construction Director for National Grid North Sea link said, “The engineering that has taken place to lay high-voltage cables below the seabed is remarkable. The difficult terrain, the depth of the waters, and all in amidst of operating during a pandemic has made it extremely challenging. Nevertheless, we have powered through and remained on track with our project timelines.”

The next milestone is to lay the cable out from the fjords in Suldal, to the North Sea this summer. This work will be carried out throughout the remainder of the year, and by 2021 the two parallel 720km cables between Cambois, Northumberland in the UK and Kvilldal, in Norway will have been completed to make North Sea Link the longest subsea power cable interconnector in the world.