UK-Norway subsea electricity cable powers past halfway point

Construction of the world's longest subsea power cable has passed a major project milestone this week, after the deployment reached its halfway point.

The North Sea Link, a joint venture between National Grid and its Norwegian counterpart Statnett, is to provide an interconnector cable that will link the UK and Norwegian electricity grids and enable the trading of excess renewable power between the two countries, enhancing both nations' decarbonisation efforts.

National Grid confirmed today that the project was running on schedule, after an innovative floating platform was successfully built to lay the cable under a lake in southwest Norway.

Once completed, the 720 kilometre interconnector will allow the UK to import enough Norwegian hydro energy to power up to 1.4 million homes, helping the country decarbonise and meet its 2050 net zero emissions target.

In order to start laying the cable in southwest Norway, the developers built a floating platform the size of two tennis courts on Lake Suldalsvatnet. The lake, which is Norway's sixth deepest, is inaccessible to the ships typically used for cable laying.

The custom-built platform allowed the team to successfully submerge parallel 2.8 kilometre high-voltage subsea cables in the lake, working at depths of up to 210 metres.

Nigel Williams, construction director for the North Sea Link, commended the "remarkable" feat of engineering, which he said had allowed the project to run on schedule.

The platform took more than two dozen people 11 days to build and was able to hold more than 150 tonnes of cable, as well as all the equipment typically found on offshore cable laying vessels, according to National Grid.

"The difficult terrain, the depth of the waters, and all in amidst of operating during a pandemic has made it extremely challenging," Williams added. "Nevertheless, we have powered through and remained on track with our project timelines."

Cable laying will continue across the fjords of southwest Norway to the North Sea this summer, National Grid said.

The 1.4GW electricity link, which will stretch 720 kilometres between Cambios in Northumberland to Kvillldal in Norway, is expected to be completed in 2021 providing a major boost to National Grid's net zero emissions goals.

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• Topics
• Infrastructure
• Energy
• North Sea Link
• Interconnector