INELFE: Baixas–Santa Llogaia

On 22 April 2013, two tunnel boring machines named Canigó and Alberas met under the Albera massif in the eastern Pyrenees. Each was 250 metres long and weighed 780 tonnes. Their 8.5 km tunnel, 7.5 km of it on the French side, was built to carry one thing: the power cables of a new link between France and Spain.

The project began with a political agreement signed in Zaragoza on 27 July 2008. On 1 October that year the two grid operators, RTE and Red Eléctrica, set up a joint company, INELFE, to build it. The reason was the Iberian Peninsula’s isolation: Spain and Portugal had only 1,400 MW of exchange capacity with France. Once the link opened, INELFE says, that figure doubled to 2,800 MW.

The route runs 64.5 km, all underground, from the converter station at Baixas near Perpignan to Santa Llogaia near Figueres. On the French side it passes villages such as Le Boulou and Le Perthus before entering the tunnel; on the Spanish side it emerges at La Jonquera and runs past Figueres. INELFE’s project page counts 260 km of cable and 144 joints in the two parallel circuits. Siemens supplied the converters and Prysmian the cable, under contracts signed on 16 December 2010. The European Investment Bank lent €350 million towards a total investment of €700 million.

The converters were voltage-source units at a power level INELFE describes as a world first for that technology. Cable was pulled through the tunnel from 31 July 2014, and commercial operation started in 2015. At 65 km it was, for a while, the longest link of its kind. The Savoie–Piémont line between France and Italy later broke that record at 190 km.

The earth dug out was not wasted: about 120,000 cubic metres of spoil went into an extension of the A-9 motorway in France.

Doubling was still not enough. The border stays congested, and the next step is the Bay of Biscay link, meant to take exchange capacity to 5,000 MW. The weakness of Iberia’s ties to the rest of Europe came back into focus in the 2025 Iberian blackout.