The 764 km (475 mile) Viking Link between Denmark and the U.K., reputed to be the world’s longest power interconnector over land and sea, is now complete. Final work on the 1.4 GW high-voltage DC interconnection was completed offshore in the North Sea by a vessel operated by cable supplier Prysmian.

Developed by National Grid Viking Link, a subsidiary of the U.K.’s National Grid, and Energinet, the Danish national transmission system operator, the £1.7 billion ($2.2 billion) project initiated in 2019 will allow transmission of enough renewable power from Denmark for 1.4 million U.K. homes.

The complex cable joining process took place in Danish waters and took several days to complete. It involved lifting the sections of cables out of the water and expertly joining each conductor/strand together on the cable laying vessel. The 1,400 MW high-voltage DC cable supplied by Prysmian and NKT is made from copper, steel, paper and plastic and is buried on the seabed. It weighs around 40 kg/m, which is three times as much as a gold bar.

Between 2020 and 2030, National Grid expects Viking Link and its five other interconnectors to have helped the U.K. avoid around 100 million tons of carbon emissions. By 2030, 90% of the energy imported through the company’s interconnectors will be from zero carbon energy sources.