Western Link is a £1.2 billion high voltage direct current (HVDC) subsea electricity link delivered and operated by SP Transmission (SPT) and National Grid Electricity Transmission (NGET). It is the highest capacity single subsea link in the world and it is also the first bi-directional subsea interconnector (capable of transmitting energy in both directions).
It connects Hunterston on the west coast of Scotland with Flintshire Bridge, on the Wales/England border, through a route of some 420km of underground cable, of which approximately 385km is subsea.
Cables being pulled ashore at Ardneil Bay in Scotland through ducts under the beach
This connection boosts the transmission of energy between Scotland and Wales and England. It helps maximise the use of Scottish renewable energy throughout the UK. With a capacity of 2,200 megawatts (MW) it is able to supply the electrical demand of more than two million homes every year. This link also makes a significant contribution to security of supply by effectively doubling Scotland’s import capacity.
A rare look inside one of the Western Link valve halls where the AC (alternating current) electricity that is used on the main network is transformed into DC (direct current) electricity to allow it to be transferred efficiently through the long cables.
With the huge potential of growing renewable energy both being connected and planned to be connected in Scotland, the Western Link is delivering long term benefits to our customers while simultaneously supporting the UK Government’s ambitions of decarbonising our economy, and ultimately enabling Net Zero carbon emissions.
Key facts on the project:
- In its first five years since its completion (2017 – 2022), Western Link transmitted 23,483GWh of green energy.
- The subsea marine cable is approx. 385km long. DC circuits can transmit power more efficiently over long distances, on fewer cables than equivalent AC circuits.
- The 600,000V cable is just 6” in diameter but weighs over 50kg / meter
- Across the planning, development and build stages of the project – Western Link supported 450 high-quality jobs in our communities.
- The Western Link is a clear example of our commitment to investing in the UK and has a planned lifespan of 40 years.
- Whilst electrical power is often expected to flow from north to south, the Western Link will allow power to flow in both directions according to future electricity supply and demand requirements.
- During the development and build of the project, marine engineers found the wreck of a WW1 German U-boat while surveying the sea bed off the coast of Wigtownshire. Folklore has it the sinking may even have been the result of an attack by a great sea monster...
Other HVDC projects
As the UK continues on its path to net-zero, further HVDC links around the coast of the UK will play a critical role in maximising the networks ability to use new renewable energy generation efficiently. We have a number of exciting HVDC links at various stages of delivery:
Eastern Green Link 1 – joint venture between SP Energy Networks and National Grid.
- EGL1 is a 196km, two gigawatt (GW) high voltage direct current (HVDC) electrical superhighway to be built between the Torness area in East Lothian, Scotland and Hawthorn Pit in County Durham, England.
- Contracts worth over £1.8 Billion have been placed with the main construction phase commencing in 2025
- It will use cutting edge 525kV XLPE cable technology and will be the first subsea system of its type in the world.
Eastern Green Link 4 – joint venture between SP Energy Networks and National Grid.
- Eastern Green Link 4 (EGL4) is a second east coast High Voltage Direct Current (HVDC) electrical link being developed in partnership with National Grid Electricity Transmission. At more than 500km it will be significantly longer than EGL1 and will connect Fife in Scotland with Norfolk in England.
Further West Coast links
We are working to understand options for further links on the West Coast based on potential future needs of the energy system.