Spanish electric utility company Iberdrola, through its British subsidiary SP Energy Networks, has awarded contracts worth over £3bn ($4bn) for the development of the Eastern Green Link 4 (EGL4) subsea electricity interconnector between Scotland and England.

Under the signed agreement, Siemens Energy will build two high-voltage direct current (HVDC) converter stations that convert alternating current to direct current, enabling transmission of electricity at 525,000 volts over long distances. The electricity will travel about 640 km, mostly underwater, before being converted back and integrated into the onshore grid.

This is the second major contract linked to this project, following the one signed earlier this year with Prysmian, worth £2bn ($2.65bn), for the supply of over 640 km of cable, of which 530 km will be subsea and 116 km underground.

With a capacity of 2GW, Eastern Green Link 4 will link Fife in Scotland with Norfolk in England and will be able to transport enough renewable energy to supply more than 1.5m homes. The main construction phase will begin in 2028, with commissioning scheduled for 2033.

This project complements Eastern Green Link 1, another 2GW link whose construction began in 2025 and will connect Torness in Scotland with Hawthorne Pit in England. This project is expected to be completed in 2029.

In total, Iberdrola will invest €14bn ($16bn) in transmission networks by 2031 to increase the UK’s capacity to transfer electricity between regions and strengthen energy security and self-sufficiency by reducing dependence on imported fossil fuels.