HVDC subsea link strengthens UK grid capacity

Expanding transmission capacity is becoming a key requirement in power systems with growing shares of renewable energy, particularly where generation and consumption are geographically separated. In this context, ScottishPower, part of the Iberdrola Group, secured £600 million in financing from the UK National Wealth Fund to support development of the Eastern Green Link 4 (EGL4) subsea transmission project.

Subsea HVDC link connecting Scotland and England
Eastern Green Link 4 is planned as a 2 GW high-voltage direct current (HVDC) subsea transmission connection between Fife in Scotland and Norfolk in England. The approximately 530 km cable is designed to transport electricity generated in Scotland to demand centres in England.

The planned transmission capacity is described as sufficient to supply electricity equivalent to the needs of approximately 1.5 million UK households. HVDC transmission is typically used for long-distance subsea links due to lower transmission losses and the ability to control power flows between grid regions.

Bidirectional transmission capability allows the link to support grid balancing and improve operational flexibility within the energy transmission infrastructure. Such projects are also intended to reduce grid constraint costs associated with limited transmission capacity between generation and consumption regions.

Financing structure and grid investment context
The financing builds on an earlier £600 million loan provided in May 2025 by the National Wealth Fund to support multiple ScottishPower grid development projects. The financing structure includes a longer-term debt profile intended to align infrastructure financing with asset lifetimes typical of transmission projects.

According to estimates from the National Energy System Operator (NESO), approximately £58 billion in grid investment will be required in Great Britain by 2035 to support the development of a low-carbon electricity system. Public financing mechanisms such as the National Wealth Fund are intended to support capital availability for such infrastructure projects.

Iberdrola has also outlined plans to invest approximately £12 billion (€14 billion) in UK transmission and distribution networks through 2028, targeting grid expansion to support increasing electricity demand linked to electrification.

Role in energy transition and network expansion
Projects such as EGL4 form part of broader grid modernisation efforts aimed at supporting domestic renewable generation and reducing reliance on imported fossil fuels. By strengthening transmission links between generation regions and consumption centres, such infrastructure can support more efficient use of renewable energy resources within the power grid modernisation strategy.

The project is also associated with planned workforce expansion in transmission network activities in central and southern Scotland, reflecting the labour requirements associated with grid expansion programmes.

Through the EGL4 project and related investments, ScottishPower continues to expand transmission infrastructure intended to support long-term electrification trends and increasing grid capacity requirements.

Edited by industrial journalist Aishwarya Mambet, with AI-assistance.

www.scottishpowerrenewables.com