The Viking Link: Bridging time and energy

When the people of Denmark are starting their day with breakfast, those in the UK are just waking up. This one-hour time difference, combined with differing peak electricity demand times, plays a significant role in the Viking Link undersea interconnector project. By aligning their energy peaks differently throughout the day, Denmark and the UK are sharing renewable energy more efficiently, reducing the overall capacity needed and maximising the utilisation of renewable sources.

The high-voltage Viking Link consists of 765-kilometre-long cables between Revsing in South Jutland and Bicker Fen in Lincolnshire, United Kingdom, making it the longest interconnector in the world.

The  two-way interconnector is a joint venture equally owned by Denmark’s Energinet and the UK’s National Grid. Operations started on 29 December 2023, with the import and export of electricity based on demand and generation capacity, thus enhancing the reliability and flexibility of supply in both countries.

Per Obbekær, Senior Project Manager for Viking Link at Energinet, was senior project manager in the final part of the construction. He explains that the time difference and peak hours are twofold for the link between the UK and Denmark.

“Evening peak is placed later in the day in the UK than in Denmark. This means the required capacity of renewable energy sources, such as wind power, needed to secure both countries’ peak loads is lower compared to if both countries required the energy at the same time,” Obbekær says.

This helps reduce the overall capacity needed and maximises the utilisation of renewable energy sources.

The Nordic Investment Bank (NIB) is co-financing the Viking Link project. In 2022, NIB signed a second 10-year loan agreement with Energinet, totalling DKK 1.5 billion, to support the construction of the interconnector.

Expanding energy connections

Denmark already has electricity connections with Norway, Sweden, Germany, and the Netherlands. With the addition of the Viking Link, Danish producers can now export electricity also to the UK when it’s windy and sunny and import when it’s needed.

“Every time we can export a renewable electron to the UK, the country can save a gas molecule and store it for when it is really needed, ultimately lowering the dependency on gas,” says Obbekær.

So far, the monthly flow from Denmark to the UK has varied from about 50% to almost 90%.

The current capacity of the Viking Link varies between 1,100 MW and 1,400 MW depending on conditions in the onshore grid. The top limit cannot now always be met, because onshore grid in the Western part of Jutland is being reinforced.

Looking ahead, the Viking Link is expected to reach its full capacity of 1,400 MW in 2026, once the Danish electricity grid is fully prepared. This will make it the largest single component in Denmark’s electricity system.

“Getting Viking Link on full capacity will enlarge the contribution, enabling the import and export of even more electricity,” says Obbekær. “This is especially important in a system with a higher share of renewable energy.”

Impact

The benefits of this enhanced connectivity are already becoming evident. In its first three quarters of operation, approximately 5,000 GWh have been shared over the link since the start of operations, with 80% sent from Denmark to the UK, according to Energinet. During this time, the Viking Link has generated about EUR 105 million. This is shared equally between Energinet and the UK’s National Grid and is used to operate and expand the Danish transmission system, reducing the need to fund these activities through electricity tariffs.

The interconnector allows both countries to exchange excess energy generated from renewable sources like wind turbines and solar panels. This not only prevents the waste of energy but also supports the increased use of intermittent renewable energy sources in both countries.

By enabling the import and export of electricity, the Viking Link promotes competition in the energy market, potentially leading to lower energy prices for consumers. It also contributes to carbon emission reduction by allowing access to cleaner energy and reducing reliance on fossil fuels.

In its first year operating at full capacity, Viking Link is expected to save 600,000 tonnes of CO₂ emissions, primarily benefiting the UK. This reduction is equivalent to removing approximately 280,000 petrol or diesel-powered cars from the roads.

Interconnectors such as the Viking Link are crucial for making an integrated European energy market.

Interconnectors—and even greater potential for cross-border trade and export—are becoming increasingly important, says Henrik Riis, Senior Vice President and CEO of Energinet Eltransmission.

“We are seeing a significant increase in electricity production from solar and wind power, and this production will fluctuate over both time and geography. Therefore, it is essential to be able to transport large volumes of electricity across Europe. More and stronger connections between countries and regions enable electricity producers to sell even large quantities of energy, thereby increasing the value of the new, renewable energy,” says Riis.

As the Viking Link progresses toward reaching its full capacity by 2026, its contribution to advancing renewable energy integration and enhancing energy security across Europe will significantly increase. This project shows the potential of international cooperation in building a sustainable energy future.