Hitachi Energy and Vinci have won contract to connect the French and Spanish electricity grids with two high-voltage direct current (HVDC) links across the Bay of Biscay.

Combined, the links will carry 2GW of electricity – enough to power some 2 million households – at 400kV over 400km, Hitachi Energy said.

Inelfe awarded the contract; it’s a joint venture of the French and Spanish grid operators handling cross-border infrastructure.

Vinci’s will design and build converter stations at the Spanish end near Bilbao and at the French end near Bordeaux. It put the value of that work at €300m.

Most of the lines’ length will run under water except for a stretch on land to avoid the undersea Capbreton Canyon.

Inelfe was set up following the 2008 Zaragoza Agreement between Spain and France. The resulting infrastructure doubled the interconnection capacity between France and Spain from 1,400MW to 2,800MW today.

The Bay of Biscay connection will take that to 5,000MW.

“Cross border, and often subsea, interconnections are vital to Europe’s increasingly interconnected grid,” said Niklas Persson, Managing Director at Hitachi Energy’s Grid Integration business.

“Through our pioneering HVDC technology, we enable Inelfe to accelerate the two countries’ sustainability goals, improving the safety, stability, and quality of electricity supply between France and Spain and the rest of Europe.”