Overview

The Gridlink Interconnector is a proposed high-voltage direct current (HVDC) submarine power cable designed to strengthen the electrical transmission link between England and France. This infrastructure project aims to facilitate the exchange of electricity between the two nations, enhancing grid stability and energy security across the Channel. The interconnector is planned to have a total transmission capacity of 1,400 MW, making it a significant addition to the existing network of cross-Channel power links. The project is operated by Gridlink, which manages the integration of the cable into the respective national grids on both sides of the border.

The physical route of the Gridlink Interconnector connects specific key nodes in the transmission networks of both countries. On the English side, the cable is designed to link to the Kingsnorth National Grid substation, located in north Kent. This substation serves as a critical entry point for power entering the English grid from continental Europe. On the French side, the interconnector terminates at the Warande substation, which is part of the Réseau de Transport d'Électricité (RTE) network. The Warande substation is situated in Bourbourg, in the Nord department, near the city of Dunkirk in northern France. This strategic placement allows for efficient power distribution into the French northern grid.

As a proposed project, the Gridlink Interconnector represents a continuation of the long-standing energy partnership between the UK and France. The use of HVDC technology is standard for long-distance submarine cables, offering advantages in terms of efficiency and control over power flow compared to alternating current (AC) systems. The 1,400 MW capacity is intended to provide substantial flexibility for energy traders and grid operators, allowing for the import of surplus renewable energy or the export of peak power depending on market conditions and generation patterns in both countries.

The development of this interconnector involves significant engineering and logistical planning, particularly regarding the submarine cable route across the English Channel. The connection between Kingsnorth and Warande requires careful coordination with local authorities, environmental agencies, and grid operators to ensure minimal disruption during construction and operation. The project's status as proposed indicates that it is in the planning or early development phase, subject to regulatory approvals and financial investments from the operator, Gridlink.

Technical specifications and design

The Gridlink Interconnector is designed as a high-voltage direct current (HVDC) submarine link, intended to facilitate efficient power transfer between the national grids of England and France. The system operates at a nominal DC voltage of 525 kV, a standard for modern HVDC links that balances insulation requirements and current carrying capacity. The total transmission capacity is rated at 1,400 MW, allowing for bidirectional power flow depending on relative electricity prices and generation profiles in both countries.

Cable Route and Submarine Infrastructure

The interconnector utilizes a submarine cable route spanning approximately 140 km across the English Channel. This length connects the coastal termination points in Kent, England, and Nord-Pas-de-Calais, France. The submarine section typically consists of single-core or three-core XLPE (Cross-Linked Polyethylene) insulated cables, selected for their thermal performance and flexibility compared to traditional oil-filled paper insulation. The cable route is engineered to minimize electromagnetic interference and mechanical stress, with burial depth varying according to seabed geology and fishing activity. The specific path links the Kingsnorth area in north Kent with the Warande substation location near Bourbourg, close to Dunkirk.

Converter Stations and AC/DC Conversion

At each terminal, converter stations transform electricity between the alternating current (AC) systems of the national grids and the direct current (DC) of the interconnector. The AC voltage level at the terminals is 400 kV, which is the standard high-voltage transmission level for both the National Grid (England) and Réseau de Transport d'Électricité (France). The converter technology typically employed in such projects is the Line Commutated Converter (LCC) or Voltage Source Converter (VSC), though the specific type is defined by the technical tender. The conversion process involves rectification at the sending end and inversion at the receiving end. The Kingsnorth converter station connects to the National Grid substation, while the French terminal connects to the Warande substation in Bourbourg.

Parameter Value
Technology HVDC Submarine Cable
Rated Capacity 1,400 MW
DC Voltage 525 kV
AC Terminal Voltage 400 kV
Total Cable Length 140 km
UK Terminal Kingsnorth, Kent
France Terminal Warande, Bourbourg

Project timeline and regulatory status

The Gridlink Interconnector project has undergone significant regulatory scrutiny, culminating in a pivotal decision by the French Energy Regulatory Commission (CRE) in 2022. The initiative aims to establish a 1,400 MW high-voltage direct current (HVDC) link between England and France, connecting the Kingsnorth National Grid substation in north Kent with the Warande substation in Bourbourg, near Dunkirk. The regulatory journey reflects the complex interplay between cross-border energy infrastructure planning and national grid operator requirements.

Regulatory Milestones

The project's timeline is marked by key regulatory steps, beginning with its inclusion in the Ten-Year Network Development Plan and subsequent designation as a Project of Common Interest (PCI). This status, achieved in 2017, facilitated funding and streamlined approval processes under EU energy policy frameworks. However, the path to final investment decision was not without challenges, particularly concerning the French side of the interconnection.

Year Event
2017 Designated as a Project of Common Interest (PCI)
2022 Rejected by the French Energy Regulatory Commission (CRE)

The 2022 rejection by the CRE was a significant setback for the Gridlink project. The commission's decision highlighted concerns regarding the integration of the new capacity into the existing French grid infrastructure and the economic viability of the connection at that time. This outcome underscores the importance of detailed technical and financial assessments in cross-border energy projects, where alignment between national grid operators and regulatory bodies is crucial for successful implementation.

Following the CRE's decision, the project's future remained uncertain, pending further negotiations and potential revisions to the technical specifications or financial models. The rejection did not necessarily signify the end of the Gridlink Interconnector but rather a critical juncture requiring strategic adjustments to address the regulatory and operational concerns raised by the French authorities.

Why it matters: The role of interconnectors in grid balancing

Interconnectors serve as critical infrastructure for enhancing grid stability and optimizing energy resource allocation across national boundaries. The Gridlink Interconnector, with its proposed 1400 MW capacity, exemplifies how high-voltage direct current (HVDC) technology facilitates efficient power transfer between England and France. By linking the Kingsnorth National Grid substation in north Kent with the Warande substation in Bourbourg, this project aims to strengthen the energy resilience of both nations.

Grid Balancing and Renewable Integration

One of the primary roles of interconnectors is to balance the variability of renewable energy sources. Wind and solar power, while abundant, are inherently intermittent. Interconnectors allow surplus energy generated in one region to be transmitted to another where demand is higher or generation is lower. For instance, when wind speeds are optimal in the North Sea, excess electricity can flow from England to France, and vice versa during periods of high solar output in France. This dynamic balancing act reduces the need for fossil fuel-based peaking plants, thereby lowering carbon emissions and enhancing the overall sustainability of the energy mix.

The integration of renewables also benefits from the diversity of weather patterns across connected regions. The Northern Seas Offshore Grid context highlights the strategic importance of such interconnections. By linking multiple offshore wind farms through a cohesive grid structure, countries can share resources more effectively. This approach not only maximizes the utilization of renewable energy but also mitigates the impact of localized weather fluctuations on power supply.

Reducing Fossil Fuel Dependency

Interconnectors play a pivotal role in reducing reliance on fossil fuels by enabling greater penetration of renewable energy into the grid. As countries aim to meet their climate targets, the ability to import clean energy becomes increasingly valuable. The Gridlink Interconnector, for example, can help France leverage its nuclear and renewable resources to meet peak demand in England, while England can export surplus wind power to France. This mutual exchange reduces the need for domestic fossil fuel generation, leading to cost savings and environmental benefits.

Furthermore, interconnectors contribute to energy security by diversifying supply sources. In times of domestic shortages or unexpected outages, the ability to draw power from neighboring countries ensures a more stable and reliable energy supply. This is particularly important for regions heavily dependent on a single energy source, such as nuclear power in France or wind power in England.

Technical Considerations

The technical design of interconnectors like Gridlink involves advanced HVDC technology, which is well-suited for long-distance power transmission. HVDC systems offer lower losses compared to alternating current (AC) systems over long distances, making them ideal for submarine cables. The efficiency of HVDC can be expressed as:

Efficiency = (Power Output / Power Input) × 100%

For a 1400 MW interconnector, even a small improvement in efficiency translates to significant energy savings. Additionally, HVDC systems provide better control over power flow, allowing operators to manage congestion and optimize the use of transmission capacity. These technical advantages make interconnectors a cornerstone of modern energy infrastructure, supporting the transition to a more sustainable and resilient energy system.

How do electricity interconnectors work?

Electricity interconnectors like the proposed Gridlink project rely on High-Voltage Direct Current (HVDC) technology to efficiently transmit power across long distances, particularly undersea. Unlike traditional Alternating Current (AC) systems, HVDC minimizes energy losses over extended routes by converting electricity into a steady flow of electrons. This technology is essential for linking the alternating current grids of different countries, such as England and France, which may operate at the same frequency but require synchronization or phase management.

The Conversion Process

The core of any HVDC interconnector is the converter station located at each end of the cable. At the sending end, AC power from the national grid is transformed into DC power. This process, known as rectification, involves using power electronics—typically thyristors or insulated-gate bipolar transistors (IGBTs)—to switch the current direction rapidly. The resulting direct current travels through the submarine cable with reduced capacitive losses compared to AC. At the receiving end, the DC power undergoes inversion, converting it back into AC to match the local grid's frequency and voltage levels. This allows seamless integration into the destination network, such as the Warande substation in France or the Kingsnorth substation in England.

Bidirectional Power Flow

One of the key advantages of HVDC interconnectors is their bidirectional capability. Power can flow from England to France or vice versa, depending on real-time demand and generation patterns. For instance, when wind generation is high in the North Sea, electricity can flow from England to France. Conversely, during peak demand in London, power can be drawn from French nuclear or hydro sources. This flexibility enhances grid stability and allows for better utilization of renewable energy resources. The control systems at each converter station manage the direction and magnitude of the power flow, ensuring efficient transmission up to the interconnector's rated capacity, such as the 1,400 MW planned for Gridlink.

Technical Considerations

The efficiency of HVDC transmission is influenced by several factors, including cable length, voltage level, and converter technology. The power loss in a DC cable can be approximated by the formula Ploss​=I2×R, where I is the current and R is the resistance of the cable. Higher voltage levels reduce the current for a given power output, thereby minimizing resistive losses. Additionally, the use of advanced converter stations with modular multilevel converters (MMC) improves efficiency and reduces harmonic distortion. These technical features make HVDC interconnectors a vital component of modern energy infrastructure, facilitating cross-border energy trade and enhancing grid resilience.

Gridlink Interconnector is a proposed submarine power cable designed to link England and France. The project specifies a capacity of 1,400 MW using high-voltage direct current (HVDC) technology. The route connects the Kingsnorth National Grid substation in north Kent, England, with the Réseau de Transport d'Électricité (RTE) Warande substation in Bourbourg (Nord), located near Dunkirk in northern France. This geographic corridor offers specific infrastructural advantages by connecting established grid nodes on both sides of the English Channel.

Route and Infrastructure

The selection of Kingsnorth and Warande as terminal points leverages existing high-voltage infrastructure. Kingsnorth in north Kent serves as a key entry point for power entering the National Grid in southeastern England. On the French side, the Warande substation in Bourbourg integrates with RTE’s transmission network in the Nord region, providing direct access to the northern French grid and facilitating power flow toward Paris and the broader European network. This direct link reduces the need for extensive onshore transmission extensions compared to routes terminating in less developed grid areas.

Comparison with Other Interconnectors

While the provided grounding details Gridlink’s specific parameters, it does not explicitly compare its capacity or route with other UK-France interconnectors such as BritNed. BritNed, for instance, connects Kent to the Netherlands, offering a different geographic vector for power exchange. Gridlink’s 1,400 MW capacity positions it as a significant addition to the cross-Channel transmission capacity, though precise comparative advantages over other links require data on those specific projects’ capacities and routes. The Kingsnorth-Warande corridor’s proximity and established substation infrastructure may offer reduced latency and lower onshore construction costs compared to links with more dispersed terminal points.

The HVDC technology specified for Gridlink is standard for long-distance submarine cables, allowing efficient power transfer with lower losses than alternating current (AC) over similar distances. This technical choice aligns with other major interconnectors, ensuring compatibility with existing grid management systems. The proposed status of Gridlink indicates that these advantages are yet to be fully realized in operational terms, pending final investment and construction phases.

See also

References

  1. "Gridlink Interconnector" on English Wikipedia
  2. Gridlink Interconnector - ENTSO-E (European Network of Transmission System Operators for Electricity)
  3. Gridlink France-UK - RTE (Réseau de Transport d'Électricité) Official Page
  4. Gridlink Interconnector - National Grid (UK) Official Page
  5. Gridlink Interconnector - ACER (Agency for the Cooperation of Energy Regulators)