Overview

Viking Link is a high-voltage direct current (HVDC) submarine power cable interconnector linking the electrical grids of the United Kingdom and Denmark. The project was completed in 2023, establishing a critical energy corridor between the two nations. It is operated jointly by British National Grid plc and Danish Energinet, reflecting a strategic cooperation between the two national transmission system operators. The interconnector has an installed capacity of 1400 MW, enabling significant bidirectional power flow between the North Sea energy markets.

As of 2024, Viking Link holds the distinction of being the longest land and subsea HVDC interconnector in the world. This extensive reach underscores the engineering scale required to bridge the geographical distance between the British and Danish coastlines. The completion of the link in 2023 marked a major milestone in the integration of European energy infrastructure, enhancing grid stability and facilitating the exchange of renewable energy resources. The operational status of the line is currently active, serving as a vital artery for electricity trade between the two countries. The collaboration between Energinet and National Grid plc has been instrumental in delivering this complex infrastructure project, which combines advanced submarine cable technology with onshore converter stations to ensure efficient power transmission.

Why it matters

The Viking Link represents a significant milestone in European energy infrastructure, distinguished as the longest land and subsea high-voltage direct current (HVDC) interconnector in the world as of 2024. This distinction underscores the project's scale and engineering complexity, bridging the United Kingdom and Denmark with a capacity of 1,400 megawatts. The completion of this link in 2023 marks a strategic advancement in the integration of the Nordic and British electricity markets, facilitated by the cooperation between British National Grid plc and Danish Energinet. By establishing a robust physical connection between these two major energy hubs, the project enhances grid resilience and facilitates more efficient power trading across the North Sea region.

Enhancing UK Interconnection Levels

A primary objective of the Viking Link is to increase the United Kingdom's electricity interconnection level. In 2014, the UK's interconnection level stood at 6%, a metric that reflects the proportion of imported and exported electricity relative to total generation. The addition of the 1,400 MW Viking Link contributes substantially to raising this percentage, thereby reducing the UK's relative isolation in the European power grid. Higher interconnection levels allow for greater flexibility in balancing supply and demand, enabling the UK to import electricity during periods of peak demand or domestic generation shortfalls and export surplus power when generation exceeds local consumption. This dynamic is particularly important for integrating variable renewable energy sources, such as wind and solar, which can fluctuate based on weather conditions. The Viking Link thus plays a crucial role in stabilizing the UK's electricity market and enhancing its energy security.

Integration with the Nord Pool Spot Market

Furthermore, the Viking Link connects the United Kingdom to the west Denmark bidding area, known as DK1, within the Nord Pool Spot market. This integration provides UK consumers and producers with direct access to the Nordic electricity market, which is characterized by a high share of renewable energy, particularly hydropower and wind power. The connection to DK1 allows for more competitive pricing and greater choice of energy sources for UK buyers, while also offering Danish producers a new outlet for their electricity. This market coupling enhances liquidity and price discovery, benefiting both sides of the interconnector. By linking the UK to the broader European energy landscape, the Viking Link fosters greater economic efficiency and supports the transition towards a more sustainable and interconnected European energy system. The project exemplifies the growing importance of cross-border infrastructure in achieving shared energy goals and enhancing regional cooperation.

Technical specifications and route

Viking Link is a high-voltage direct current (HVDC) submarine power cable connecting the United Kingdom and Denmark. The interconnector has a nominal capacity of 1400 MW and operates at a voltage of 525 kV. According to project documentation, the link provides an annual transmission capacity of 12.3 TWh, facilitating significant energy exchange between the two national grids. The system was commissioned in 2023 and is jointly operated by Danish transmission system operator Energinet and British National Grid plc. As of 2024, Viking Link holds the distinction of being the longest land and subsea HVDC interconnector in the world.

Route and Geography

The total length of the Viking Link cable system is 765 km. Of this distance, 650 km runs undersea, traversing the North Sea. The route passes through the territorial waters of four nations: Denmark, Germany, the Netherlands, and the United Kingdom. A notable feature of the subsea path is its crossing of the existing NorNed cable system. The NorNed interconnector spans 580 km and connects the Netherlands to Germany, creating a complex junction point for North Sea power infrastructure. The remaining portion of the Viking Link consists of land-based cable sections on both the Danish and British shores, completing the connection between the two national grids.

Parameter Value
Technology High-Voltage Direct Current (HVDC)
Capacity 1400 MW
Voltage 525 kV
Annual Transmission Capacity 12.3 TWh
Total Length 765 km
Subsea Length 650 km
Commissioning Year 2023
Operators Energinet, National Grid plc
Countries Connected Denmark, United Kingdom
Waters Traversed Danish, German, Dutch, British

The development of Viking Link began with its inclusion on the European Union’s list of ‘Projects of Common Interest’ in 2015, establishing the strategic framework for the cross-channel interconnector. This early recognition facilitated the financial and regulatory alignment necessary for a joint venture between British National Grid plc and Danish Energinet. The project advanced to a critical procurement stage in 2017, when a tender was launched for an estimated €1.3 billion, setting the economic baseline for the infrastructure build-out.

Contracting and Procurement

By 2019, the consortium secured key supply chain agreements, awarding contracts to major industry players Siemens Energy, Prysmian Powerlink, and NKT HV Cables. These agreements totaled €1.1 billion, covering the high-voltage direct current (HVDC) converter stations and the extensive submarine cabling required for the link. The selection of these partners ensured the integration of advanced HVDC technology capable of handling the 1400 MW capacity across the North Sea.

Construction and Cable Laying

Physical construction commenced in mid-2020, marking the transition from planning to execution. In 2021, Balfour Beatty undertook significant drilling operations to prepare the landfall sites and terrestrial corridors. The most complex phase involved the subsea cable installation. Prysmian Powerlink was responsible for laying 870 km of the 1250 km dual subsea cable system. The remaining 380 km of cabling was completed in 2023, finalizing the physical connection between the two nations.

Testing and Commissioning

Following the completion of the cable laying, the link underwent rigorous technical validation. In August 2023, the system was subjected to 735 kV testing to verify voltage stability and transmission efficiency. These successful tests paved the way for the official commissioning of Viking Link in 2023. As of 2024, the infrastructure stands as the longest land and subsea HVDC interconnector in the world, enhancing energy security and renewable integration between the United Kingdom and Denmark.

Viking Link commenced commercial operations on 29 December 2023, marking a significant milestone for the UK-Denmark interconnection. Despite the completion of the submarine cable, the project faced immediate operational constraints due to the asynchronous integration of supporting infrastructure in Denmark. Specifically, the full utilization of the interconnector’s rated capacity was hindered by the delayed commissioning of a critical 400 kV supporting power line on the Danish side. This infrastructure gap forced operators to limit the transmission capacity to 800 MW, effectively halving the potential throughput of the 1,400 MW link. The delay in finalizing the Danish grid reinforcements pushed the timeline for full capacity restoration to late 2025, creating a period of reduced efficiency for the asset during its initial operational phase.

Early Operational Incidents

The early operational period also revealed vulnerabilities in the onshore infrastructure. In February 2024, the interconnector experienced a notable outage triggered by a fire at the Revsing converter station in Denmark. This incident highlighted the exposure of the HVDC system to terrestrial risks, beyond the traditional challenges associated with subsea cable maintenance. The fire at Revsing temporarily disrupted power flows, underscoring the importance of robust fire protection and rapid response protocols at critical converter nodes.

Conversely, the link demonstrated its strategic value during broader North Sea grid maintenance activities. In January 2024, Viking Link operated at full capacity to compensate for the maintenance of the COBRAcable interconnector. This event illustrated the interconnector’s ability to deliver high-volume power transfers when required, despite the ongoing constraints related to the Danish 400 kV line. The successful full-capacity transmission during the COBRAcable maintenance period provided early evidence of the link’s technical reliability, even as the project navigated the logistical challenges of integrating with the existing continental grid infrastructure.

Economic impact and benefits

The Viking Link project represents a substantial capital investment in European energy infrastructure, with estimated costs reaching 13.4 billion DKK. This financial commitment by Energinet and National Grid plc underpins the interconnector’s role in stabilizing and optimizing power markets between Denmark and the United Kingdom. Economic analyses conducted prior to full operational status highlighted significant potential returns. A 2016 analysis projected an overall benefit of DKK 5.6 billion for the project. Furthermore, the study identified a specific DKK 20 billion benefit associated with heat pump integration, contributing to a total projected benefit of DKK 22.8 billion. These projections informed price expectations leading up to the 2022 period, setting the stage for the financial performance observed after the 2023 commissioning.

Operational Earnings and Revenue

Following its completion in 2023, the interconnector began generating tangible financial returns for its operators. By the first quarter of 2024, the Viking Link reported earnings of approximately 20 million Euro. This revenue stream is split between the two primary stakeholders: National Grid plc and Energinet. The earnings reflect the successful monetization of the capacity, driven by price differentials between the two national grids and the efficient utilization of the high-voltage direct current (HVDC) technology. The financial performance in early 2024 demonstrates the interconnector's ability to capture value from cross-border energy trading shortly after entering service.

Transmission Statistics and Utilization

The economic benefits are directly correlated with the physical volume of energy transmitted. In the first quarter of 2024, the Viking Link facilitated the transmission of 1,733 GWh of electricity. This volume corresponds to a capacity factor of 55%, indicating a strong initial utilization rate for the 1,400 MW link. The flow of energy was predominantly unidirectional during this period, with 80% of the transmitted power moving from Denmark to the United Kingdom. This flow pattern reflects the prevailing energy mix and demand dynamics between the two countries, leveraging Denmark’s renewable generation capabilities to supply the UK market. The high capacity factor and significant transmission volumes underscore the interconnector’s immediate impact on regional energy economics.

Comparison with other interconnectors

Viking Link is classified as an EU Project of Common Interest, a status it shares with the COBRAcable interconnector and the Krieger offshore wind turbine cable. These projects are grouped under the European Union’s framework to enhance energy market integration and security of supply across member states and partner nations. While Viking Link connects the United Kingdom and Denmark, COBRAcable links France and the United Kingdom, and the Krieger cable facilitates power transmission from offshore wind farms in the North Sea. All three initiatives utilize high-voltage direct current (HVDC) technology to minimize transmission losses over long distances, though their specific lengths and capacities vary significantly based on geographic and engineering requirements.

Capacity and Length Comparisons

When compared to the North Sea Link, which connects the United Kingdom and Norway, Viking Link demonstrates distinct advantages in length. As of 2024, Viking Link is recognized as the longest land and subsea HVDC interconnector in the world. The North Sea Link, while also a major HVDC submarine cable, is shorter in total distance. In terms of capacity, Viking Link has a rated capacity of 1,400 MW. The North Sea Link also has a significant capacity, but specific comparative figures for COBRAcable and the Krieger cable are not detailed in the provided grounding snippets, limiting direct numerical comparison for those specific projects.

Project Route Capacity Notable Feature
Viking Link UK – Denmark 1,400 MW Longest land and subsea HVDC interconnector (as of 2024)
COBRAcable France – UK [?] EU Project of Common Interest
North Sea Link UK – Norway [?] Major HVDC submarine cable

The cooperation between British National Grid plc and Danish Energinet for Viking Link mirrors the collaborative models seen in other major interconnector projects. However, Viking Link’s distinction as the longest such cable highlights the engineering scale required to bridge the geographical gap between the two nations. The EU Project of Common Interest designation underscores the strategic importance of these links in balancing renewable energy generation, particularly wind power, across the North Sea region.

Frequently asked questions

The Viking Link serves as a high-voltage direct current (HVDC) submarine cable that connects the electricity grids of the United Kingdom and Denmark. It enables the two nations to trade power, enhancing energy security and integrating renewable sources like wind energy across the North Sea.

The interconnector officially began operations in 2023, marking a significant milestone in North Sea energy infrastructure. This timeline followed years of planning and construction to link the grid systems of the UK and Denmark.

The Viking Link has a total transmission capacity of 1,400 megawatts (MW). This substantial capacity allows for significant volumes of electricity to be moved between the two countries, helping to balance supply and demand on both sides of the North Sea.

It plays a crucial role in stabilizing electricity prices and improving grid reliability by allowing surplus power to flow from one country to the other. This interconnection is particularly valuable for integrating variable renewable energy sources, such as offshore wind farms, into the broader European energy network.

As one of the major HVDC links in the region, it is often compared to other cables like the NorNed or the BritNed interconnectors in terms of capacity and route. These comparisons highlight its strategic position in connecting the Nordic power market with the larger UK grid, facilitating cross-border energy trade.

References

  1. Viking Link - National Grid
  2. Viking Link - Energinet
  3. Viking Link - Ofgem
  4. Viking Link - ACER (European Network of Transmission System Operators for Electricity)

See also