Under construction · HVDC · subsea
Bay of Biscay Interconnection
A 2,000 MW subsea link under the Bay of Biscay, meant to end the Iberian grid's near-isolation from the rest of Europe.
Route © OpenStreetMap contributors; outlines: Natural Earth.
- Route
- Spain to France
- From
- Gatika, near Bilbao
- To
- Cubnezais, near Bordeaux
- Length
- 400 km
- Of which subsea
- 300 km
- Capacity
- 2,000 MW
- Type
- HVDC · subsea and land cable
- Status
- Under construction (checked September 2026)
- Expected
- 2028
- Operators
- Red Eléctrica, RTE (via INELFE)
In May 2019 engineers surveying the seabed off south-west France found unstable ground near the Capbreton Canyon, a deep trench that cuts into the continental shelf close to the coast. By October the crossing had been abandoned and the route redrawn. That detour is one reason the Bay of Biscay link, planned since the 2010s, is still under construction.
The purpose is simple. Spain and Portugal have 2,800 MW of exchange capacity with France, and INELFE says that capacity was saturated in 76% of hours over three recent years. INELFE also points to the EU’s interconnection targets, 10% by 2020 and 15% by 2030. The new link, two 1,000 MW circuits in four cables, would lift the border to 5,000 MW.
The route starts at the Gatika substation near Bilbao, comes ashore on the Spanish side at Lemoiz after 13 km of buried cable, and crosses roughly 300 km of seabed. In France it lands on the Landes and Gironde coast (INELFE names Le Porge, Seignosse and Capbreton), then runs 80 km underground through the Médoc to the converter station at Cubnezais, north of Bordeaux.
The money has moved a lot. The first estimate was €1.75 billion; in March 2023, when the main contracts were awarded, construction inflation had pushed it to €3.1 billion. The EU’s Connecting Europe Facility gave €578 million, €350 million to the French side and €228 million to the Spanish side. In June 2025 the European Investment Bank added a €1.6 billion loan. The French energy regulator CRE and its Spanish counterpart had already agreed in 2017 how to split costs across the border, a step open only to Projects of Common Interest.
Work started in France in October 2023, and the foundation stone of the Cubnezais converter station was laid in May 2025. INELFE’s schedule shows marine cable work from late 2025 to mid-2027, converter stations finishing in late 2028, and testing from mid-2027 into 2028.
If you want to know why this matters, the guide to the 2025 Iberian blackout sets out what a weakly connected peninsula looks like on a bad day. The existing eastern link through the Pyrenees is described on the INELFE page.
Against the other links
- 16th longest of the 54 links with a published length; the longest is Tyrrhenian Link at 970 km.
- 4th largest by capacity of 60; SuedLink leads with 4,000 MW.
- Other links from the same countries: AQUIND Interconnector, Celtic Interconnector, ElecLink, IFA (Interconnexion France-Angleterre), SACOI (Sardinia–Corsica–Italy), SACOI 3.
Bay of Biscay Interconnection in brief
How long is Bay of Biscay Interconnection?
400 km, of which 300 km under the sea, which makes it the 16th longest of the 54 links in this directory with a published length.
How much power can Bay of Biscay Interconnection carry?
2,000 MW, 4th of 60 by capacity here.
When will Bay of Biscay Interconnection be finished?
The published target is 2028.
Which countries will Bay of Biscay Interconnection connect?
Spain and France: Gatika, near Bilbao to Cubnezais, near Bordeaux.
Who is behind Bay of Biscay Interconnection?
Red Eléctrica and RTE (via INELFE).