Linking the UK and Norway via the world's longest subsea power cable

North Sea Link, a joint venture project between National Grid Ventures, part of National Grid, and Norwegian system operator Statnett, will connect the electricity systems of two countries via high voltage subsea cables from Kvilldal in Norway to Blyth in the UK.

Known as an 'interconnector', the subsea cable passing through Norwegian and British waters, will be the longest subsea power cable in the world, when operational in 2021.

North Sea link will provide additional transmission capacity for electricity to be traded between the UK and Norway to the benefit of both countries.

To meet domestic and international renewable and climate change targets, North Sea Link will help increase opportunities for shared use of renewable energy - a mix of generation, including wind power from the UK and hydropower from Norway.

During the early part of summer, whilst laying down part of the subsea power cable, the project team carried out a major engineering feat.

Before being able to lay the cable in Norway, the team first had to tackle manoeuvring the cable through a beautiful lake, inaccessible by the size of the vessel, usually required for cable laying.

The team transported materials piece by piece to build their own custom-made floating platform. The operation was the first of its kind in this scale in Norway, and the construction of the platform had an average of 25 people working on it daily over the course of 11 days. This unique operation in Suldalsvatnet, marked the start of the cable laying on the Norwegian side.

Working at depths of up to 210 metres, the laying of the 2.8km parallel subsea cables was executed from a 43x15 metre platform - equivalent to the size of two tennis courts.

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 technical equipment that is usually found on offshore cable laying vessels.

 

"The engineering that has taken place to lay high-voltage cables below the seabed is remarkable," says Nigel Williams, construction director for National Grid North Sea link. "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."

Following this major feat of engineering, the next milestone was to lay the cable out from the fjords in Suldal, to the North Sea. This work started this summer, 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.

By the end of 2021, North Sea Link will be operational. In periods with dry weather in Norway, North Sea Link can also export 1.4GW electricity to the Norwegian market and the electricity interconnector will also allow the UK to import enough clean energy to power up to 1.4 million homes.

North Sea Link will be National Grid's fifth interconnector to Europe. The company already has three operational interconnectors - France (IFA), the Netherlands (BritNed) and Belgium (Nemo Link). Two further projects are also under construction - France (IFA2, operational 2020) and Denmark (Viking Link, operational 2023).

By 2030 90 per cent of electricity imported via National Grid's interconnectors will be from zero carbon sources.

 

This is a contributed article from National Grid, which is a partner of the world's first Net Zero Festival taking place over three days from 30 September

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