Home / The electricity interconnection across the Biscay Gulf

The electricity interconnection across the Biscay Gulf

Up to 5,000 MW


370 km


4 cables


2 x 1,000 MW


The electricity interconnection between  Gatika (Spain) and Cubnezais (France) will be the first fundamentally submarine interconnection between Spain and France.

This project will increase the exchange capacity from 2,800 to 5,000 MW,  increasing the safety, stability and quality of electricity supply between the two countries and also with the rest of Europe.


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Converter station
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80 km

Underground direct current link


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280 km

submarine direct current link
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10 km

Aerial/ underground direct current link


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Converter station

Public participation

Each State will analyse and authorise the project based on its own procedures for electricity infrastructure. Besides prior consultation in each country based on their respective regulations, France and Spain must guarantee public participation and public access to information in accordance with European requirements for all Projects of Common Interest. These actions can be undertaken in a variety of ways but should at least have a website dedicated to the project, public meetings and a specific organisation capable of guaranteeing the collection of comments and responding to any type of question. This will ensure the population feels involved in the various stages to define the routes and technical specifications of the project.


You will find all the documentation related to the process of public participation in France in the French webpage version.

Project managers

Etienne Serres
Project leader in France

Marc Chambily
Consultation process manager in France

You will find more documentation related to the process of public participation in Spain in the Spanish webpage version.

Project managers

Juan Prieto
Project leader in Spain

Antonio Miranda
Consultation process manager in Spain

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Project leaflet

Download all the information 

Biscay Gulf project leaflet
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The route

The interconnection consists of four cables, two per link. This submarine and underground direct current dual connection will be 370 km in length, running between the Cubnezais substation (near Bordeaux, France) and the Gatika substation (near Bilbao, Spain). It will have two converter stations - one at each end of the link - that will convert the direct current to alternating current for connection to the electricity transmission grid of each country.

The submarine section

The link will connect to the Gatika electricity substation (in Bilbao) and the Cubnezais substation (to the north of Bordeaux). The submarine section will be approximately 280 km in length, from the Basque coast to the French Médoc coast.
The choice of route and placement of the cable on the sea floor will minimise the impact on maritime activities, especially fishing.

Submarine cable laying

The submarine cable

Each cable will be placed on the sea bed with the help of a cable-laying ship. Generally-speaking, the cables will be buried for protection except where the ground is too hard, where they will be covered.

Aerial/underground section

The interconnection will be connected to the Gatika substation, located to the north-east of Bilbao and 10 km from the Basque coast.

To do so, the existing Gatika-Lemoiz infrastructure comprising two 400 kV electricity power lines will be used. The route will leave the converter station to be built near the Gatika substation heading towards the Bay of Biscay area.

The process for presenting the document will be carried out in accordance with the Spanish Environmental Impact Assessment procedure, and the document will summarise the following: the characteristics and location of the project; the analysis of the potential impacts from the various alternatives for the converter and the line; and a territorial and environmental diagnosis of the effects caused by the project.

The link will connect to the Cubnezais electricity substation located to the north of Bordeaux. Hence, the underground section will run for less than 100 km from the right bank of the River Dordogne, passing beneath this river and the Garonne to reach the Aquitaine coast via the Médoc region, fully respecting the environment and human activity. Numerous factors must be considered in this coastal region, such as: environmental awareness, busy beaches, urban centres, awareness of coastline regression and the possibility of using infrastructures that already exist to sleave rapidly the coastline. The most suitable landfall points are located in the Médoc coast area.

The underground cable

The underground cable

Trench: Each trench will contain a pair of cables, and the two trenches will be separated by a minimum distance of 1 m Once work is completed, they will be covered over to hide them from sight.

Junctions: The underground cables will be installed in sections of approximately 1 km, each connected via a junction chamber. A similar, albeit slightly larger, device will be used to connect the submarine cables to the underground cables. These devices will be located far from the shore and will eventually be covered over because permanent access is not required, leaving them totally hidden from view.


Converter station

The connection will link two alternating current systems via a submarine direct current line.
At each end of the connection, the converter stations will convert the direct current into alternating current for connection to the transmission grids of Spain and France.

The converter stations cover an area of approximately 5 ha and will be approximately 20 m high.

Converter station





Impact study and public information


Technical authorisations

2020 - 2024

Supply and construction

2024 - 2025

Testing and commissioning

In the absence of a viable crossing route, RTE and REE launch new studies to bypass the Capbreton Canyon

As part of the studies prior to the construction of the new interconnection between France and Spain via the Biscay Gulf, RTE and REE carried out geological studies of the seabed. They revealed ground instability along the edge of the Capbreton Canyon. Additional analyses conducted since June have not identified a route under the canyon that is guaranteed to be stable for the life of the power line.
RTE and REE are therefore forced to abandon this solution and define a new route around the canyon.

Learn more

RTE and REE perform additional analysis to secure the Biscay Gulf project

As part of the studies prior to the construction of the new interconnection between France and Spain via the Biscay Gulf, RTE and REE carried out extensive geological studies of the seabed. The latest studies, at the beginning of May, revealed soil instability very close to the Capbreton canyon, in French waters.

Learn more

Meeting with suppliers in Brussels

Inelfe organised a meeting with HVDC cable, converter station, submarine cable and drilling suppliers in Brussels. Held between 16 and 20 April, its goal was to explain the scope of the interconnection project between Spain and France via the Bay of Biscay and to exchange information on the best way to implement the project (technology, materials, implementation procedures, etc.). Learn more

Supplier´s Event 2018

HVDC cables and converter stations for the Biscay Gulf electricity interconnection between France and Spain Learn more




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