UK and Denmark turn on 'world’s longest land and subsea interconnector'

The 1.4GW Viking Link electricity interconnector became operational between the UK and Denmark today (Friday), heralding the start-up on what the two countries grid system operators are describing as the world's longest land and subsea link of its kind.

The £1.7bn ($2.16m) link— a joint venture between National Grid and Danish System Operator, Energinet — stretches 475 miles (764km) between the Bicker Fen substation in Lincolnshire, UK, with Revsing substation in southern Jutland, Denmark. 

UK Energy Security Secretary Claire Coutinho said: “The longest land and subsea electricity cable in the world and will provide cleaner, cheaper more secure energy to power up to 2.5m homes in the UK.

Coutinho said access to imported electricity from Denmark "will help British families save £500m on their bills over the next decade, while cutting emissions".

Viking Link has a converter station on each end of the cable where the power is transformed into the correct frequency before being transported onto each country’s transmission systems.   

Principal Contractor Siemens Energy built the converter station in the UK while Energinet built the Danish converter station.  Siemens Energy designed, installed and commissioned the electrical assets on both sides.

The HVDC offshore cable was manufactured and laid in the North Sea by Prysmian Group. The cable was laid on the seabed using the Leonardo Da Vinci vessel and was buried using Asso trenchers.   

Ramp-up

Initially, Viking Link will be operating at a capacity of 800MW before increasing up over time to 1.4GW. National Grid and Energinet will be working together to bring the asset up to full capacity over the coming year.

In its first year of operation Viking Link is expected to save approximately 600,000 tonnes of carbon emissions, according to today's statement by National Grid.

National Grid’s interconnector business is run by National Grid Ventures (NGV), which operates outside of National Grid’s core regulated businesses in the UK and US.

President of National Grid Ventures Katie Jackson said: “This record-breaking new link is a fantastic example of engineering and collaboration with our partner, Energinet. As we deploy more wind power to meet our climate and energy security targets, connections to our neighbouring countries will play a vital role increasing security of supply and reducing prices for consumers."

Managing Director of National Grid Interconnectors Rebecca Sedler stated: "Viking Link is an achievement for both Denmark and the UK, and consumers in both countries will benefit from this infrastructure for many years to come.”

Construction on Viking Link, National Grid’s sixth interconnector, started in 2019.

National Grid launched the UK’s first interconnector to France in 1986 and has since built five more including a second link with France and further connections with The Netherlands, Belgium (Nemo Link) and Norway.

Earlier this year (2023) National Grid announced joint plans with TenneT for a new 1.8GW interconnector between the UK and The Netherlands, called LionLink.

The proposed second interconnector with the Netherlands would also connect to offshore wind generation and is expected to be operational in the early 2030s.

A second new link called Nautilus, is also in the planning phase with the potential to connect with Belgium, National Grid stated.

Note of caution

But amid the celebrations of the Viking Link start up, some notes of caution were also sounded.

"The electrification of energy consumption is not a smooth process, even in the North Sea region, where littoral states are rich in wind-power potentials and have invested much in advancing the industry," wrote Francesco Sassi, a research fellow in energy geopolitics and markets from Pisa University in Italy.

"The viability of the Viking Link project is connected with the expansion of the high-voltage electricity grid in West Jutland and down to the border between Denmark and Germany. These works have been delayed on the Danish side.

"Electricity could be easily sold to UK consumers at higher prices compared to the Nordic system prices, securing revenues for Danish wind power producers. However, this remains impossible until the weak West Jutland grid is updated. Something which is expected not before 2025".

On the UK side, the government is also targeting the delivery of 50GW of offshore wind by 2030 and the decarbonisation of the power system by 2035.

To reach net-zero by 2050, the electricity sector is also set to almost triple in size, with more than 50% of generation expected to come from offshore energy, by 2050.

In an attempt to rise to this challenge England, Wales & Northern Ireland seabed manager, The Crown Estate, and the Electricity System Operator (ESO) recently signed a renewed statement of intent to collaborate more closely on future strategic planning.

" These future scenarios call for a vastly more coordinated approach to seabed leasing and the delivery of transmission infrastructure to realise the UK’s clean energy potential, while considering other seabed users and the natural environment," The Crown Estate stated, upon signing the renewed statement of intent earlier this month.

The agreement covers enhancement of information-sharing on seabed leasing plans and grid design options to best enable future seabed leasing activity and energy infrastructure planning.

It also focuses on how to accelerate the deployment of transmission infrastructure in Great Britain with application of a Strategic Spatial Energy Plan (SSEP) that sets out what needs to be built, where, and when to deliver on 2035 targets, and a Marine Delivery Routemap.

Gus Jaspert, marine managing director, The Crown Estate, said: “The decisions the UK needs to make over how best to use this precious (marine) resource to support a growing set of priorities, including net-zero, energy security and nature recovery, are becoming ever more complex. More long-term visibility is needed on how the marine space can be managed to fulfil these competing demands and unlock vital investment for the future.

“This holistic and forward-looking planning will not only help to improve the deliverability of offshore projects and reduce costs but will also provide visibility and certainty to support targeted investment across the range of interests that rely on our seabed for their survival.”