ElecLink

The ElecLink HVDC project is a significant electrical interconnector between the United Kingdom and France, designed to enhance energy exchange and security between the two countries. This 320kV high-voltage direct current (HVDC) bi-directional interconnection system is capable of transferring up to 1GW of electricity through the Channel Tunnel.

Project Overview

ElecLink, a wholly-owned subsidiary of Getlink (the owner of the Channel Tunnel concessionaire, Eurotunnel), owns and operates this cross-border transmission system. The project is unique in being the first interconnector in Europe fully financed through private funds, with an estimated investment of approximately £540 million (€580 million).

The European Union recognized ElecLink as a Project of Common Interest in 2013, and the European Commission approved a regulatory exemption for up to 800MW for 25 years in July 2014. Construction began in 2016, with the main works completed by the end of 2020. The cable pull through the Channel Tunnel was completed in 2021, and the system became commercially operational on May 25, 2022.

Technical Specifications

The ElecLink Interconnector consists of two converter stations: one in Folkestone, UK, and another in Peuplingues, France. These stations are connected by approximately 51km of bi-directional HVDC cables passing through the existing Channel Tunnel. The project utilizes voltage-sourced converters in a modular multilevel converter arrangement (VSC-MMC) to convert electricity between DC and AC. End-to-end physical losses are approximately 2.5%.

The Folkestone converter station connects to National Grid Electricity Transmission's substation in Sellindge, UK, via 14.5km of underground AC cable. Similarly, the Peuplingues converter station links to Réseau de Transport d'Électricité's substation in Les Mandarins, France, through 3.5km of underground AC cable.

Environmental Impact and Capacity

When completed, ElecLink increased the pre-existing interconnection capacity between the UK and France by approximately 50%. It has the potential to supply electricity to about two million households in both countries. The project aims to contribute to the low carbon transition efforts of both nations by potentially offsetting around 6.1 million tonnes of carbon dioxide emissions annually.

Construction and Implementation

The project involved several key contractors. Siemens Energy was awarded an engineering, procurement, and construction contract for the two converter stations. A consortium of Balfour Beatty and Prysmian was responsible for manufacturing and installing the DC cables in the tunnel and the underground AC cable system in the UK. RTE oversaw the installation of underground AC cables in France, while National Grid Electricity Transmission supervised the connection works at the Sellindge substation in the UK.

Innovative Features

ElecLink incorporates several innovative features. It is the first electricity interconnector between the UK and France since 1986 with the capacity to power over 1.5 million households. As a non-subsea link between continental Europe and Great Britain, it has zero impact on the marine environment. The project also employs state-of-the-art monitoring solutions, including the first-ever monitoring system installed in a railway tunnel.

Installation Process

The installation of the HVDC cables in the Channel Tunnel involved innovative techniques: A hexagonal monorail track was installed along the entire length of the tunnel. Two 7-metre-high, 4-track helices were constructed, one at each end of the tunnel. A cable carrier capable of transporting 2.5 km sections of HVDC cable was used to install the cables in the tunnel.

Monitoring System

The ElecLink project incorporates PRY-CAM monitoring solutions, marking the first-ever monitoring system installed in a railway tunnel. This system enables online measurement of key parameters for asset condition diagnosis and remote defect localization.

Challenges and Solutions

One of the unique challenges of the ElecLink project was installing HVDC cables just 50 cm away from running trains in the Channel Tunnel. This required extensive risk assessments and safety considerations, overseen by the Channel Tunnel Intergovernmental Commission and the Channel Tunnel Safety Authority.

To address the challenges of working in a live railway environment, the construction team developed innovative solutions. These included an automated cable management system using articulated cable carriages mounted on a monorail system, and a bespoke engineering works train with automated arms for efficient installation of brackets and bolts.

Economic and Energy Security Impact

ElecLink plays a crucial role in strengthening energy security for both the UK and France. It allows for more efficient energy distribution and potentially leads to reduced fuel costs. The interconnector facilitates the sharing of renewable energy resources between the two countries, contributing to their respective energy transition goals.