IN Brief:
- Eastern Green Link 2 will transfer 2GW between Scotland and Yorkshire.
- The 505km HVDC project includes subsea cable, underground cable, and two converter stations.
- The £4 billion-plus link is scheduled to enter operation in 2029.
SSEN Transmission and National Grid Electricity Transmission have moved the Eastern Green Link 2 project into its main construction phase as work advances at both ends of the 2GW high-voltage direct-current connection.
The project will run approximately 505km between Peterhead in Aberdeenshire and Drax in North Yorkshire. Most of the route will be subsea, with underground onshore cable sections connecting new converter stations to the existing transmission network.
Operating at 525kV DC, Eastern Green Link 2 will be capable of transferring up to 2GW, equivalent to the electricity demand of around two million homes. Its investment value exceeds £4 billion, placing it among the largest individual transmission projects undertaken in Great Britain.
Geotechnical investigations have been completed along key parts of the route, while further marine engineering surveys are supporting detailed cable design and installation planning. Onshore works include site preparation, civil construction, underground cable routes, converter-station infrastructure, and connections into the AC transmission system.
HVDC is suited to long-distance bulk transfer because it can move substantial quantities of electricity with controllable power flows and lower losses than an equivalent long submarine AC connection.
Converter stations at Peterhead and Drax will change alternating current into direct current for transmission and convert it back before delivery into the receiving network. Their control systems will also regulate the direction and magnitude of the transfer.
That controllability is particularly valuable where Scottish renewable output can vary substantially and where the existing transmission system is frequently constrained. Power can be scheduled around network conditions rather than following the natural distribution of flows through the surrounding AC system.
Eastern Green Link 2 forms part of a wider programme to reinforce the network between renewable-generation regions and major demand centres. Scotland’s onshore and offshore wind pipelines are increasing the requirement for north-to-south transfer capacity, while electrification and large industrial loads are altering demand elsewhere.
The subsea cable installation will require route preparation, crossing design, burial assessment, and coordination with fisheries, shipping, environmental restrictions, and existing seabed infrastructure. Depending on local conditions, protection may involve burial, rock placement, or other mechanical measures.
Cable manufacture and installation must also account for thermal performance, mechanical loading, jointing, seabed movement, and the risk of external damage. Repairing a long offshore HVDC cable can require specialist vessels and extended outages, making route engineering and protection central to lifetime reliability.
Onshore sections carry their own design requirements. Underground cables need joint bays, access arrangements, thermal assessment, earthing, and reinstatement, while converter stations contain power semiconductors, transformers, reactors, switchgear, cooling systems, harmonic filters, protection, controls, and auxiliary electrical systems.
The converter equipment will need to operate through a range of normal and abnormal system conditions, including power reversal, voltage variation, network faults, and planned outages. Harmonic performance, reactive-power exchange, control interaction, and protection coordination must be demonstrated before commercial operation.
Delivery depends on a limited international supply chain for HVDC cable, converter equipment, specialist installation vessels, and high-voltage engineering. Manufacturers and contractors are serving simultaneous interconnector, offshore wind, and national reinforcement programmes across Europe.
Factory slots and vessel availability can therefore influence the programme years before peak site activity. Long-lead transformers, converter valves, cable systems, and control equipment must arrive in sequence with civil works and network outages.
The project sits within the £70 billion programme of electricity-network investment planned by National Grid, where regulatory approval, procurement, manufacturing, construction, and commissioning must progress in parallel.
It is also one of several proposed eastern HVDC routes. Eastern Green Link 5 has entered public consultation, extending the strategy of using high-capacity offshore links to supplement the existing onshore transmission system.
Additional transfer capacity will interact with AC circuits, other HVDC links, generators, interconnectors, and regional constraints. Protection coordination, converter controls, restoration arrangements, and planned outages must therefore be integrated with the wider electricity system.
Commissioning will proceed through staged energisation and testing of the cable system, converter stations, communications, protection, and control functions. Performance must be demonstrated across normal operation, power reversal, equipment outages, faults, and defined grid-code conditions.
Scheduled to enter service in 2029, Eastern Green Link 2 has now moved beyond surveys and enabling work into the period when cable manufacturing, converter delivery, civil engineering, and grid integration will determine the programme.
