Saint-Brieuc: Iberdrola's first large-scale offshore wind power project in Brittany

When it becomes operational in 2023 it will have a total installed capacity of 496 megawatts (MW), capable of generating enough clean energy for 835,000 people.

Saint-Brieuc Bay, France

Wind turbines number
62 SG 8.0-167 DD turbines

16 km off the coast of Brittany

Total installed capacity
496 MW

2.4 billion euros

Start of the operational phase

Saint-Brieuc Project
Offshore wind farm

Brittany is prone to strong winds and high tides, which have shaped the region's landscape, economy and way of life. With a view to leveraging the region's full energy potential, the company designed the Saint-Brieuc offshore wind farm: the first large-scale offshore wind farm in Brittany and one of the first in France to obtain all the necessary government permits for its construction and operation.

With an investment of 2.4 billion euros it is estimated that, once commercialisation begins in 2023, it will produce 1,820 gigawatt hours (GWh) per year, which will supply energy to 835,000 people.

This will be possible thanks to a total installed capacity of 496 megawatts (MW) from 62 turbines each generating 8 MW of power, which will cover a surface area of 75 km2 located some 16 km off the French coast.

The wind farm is being built in collaboration with the French companies RES and Caisse des Dépôts, both part of the Ailes Marines consortium owned by Iberdrola following the acquisition of all its shares.

Once operational it will become the company's fourth installation of this type, after West of Duddon Sands in the Irish Sea; Wikinger, in the Baltic Sea; and East Anglia ONE, one of the biggest offshore wind farms in the world, located in the south of the North Sea.


Saint-Brieuc offshore wind farm location.#RRSSSaint-Brieuc offshore wind farm location.


Work has already started and will continue for three years. The first phase is underway in the northern part — so that fishing activities can continue in the southern part — where five specific areas have been identified to be worked on in rotation.

In 2020, the analysis of the technical and environmental conditions was completed, thanks to the installation of three wind measuring systems, in the area where the farm is situated, which spent two years recording the wind power potential of the area using the LIDAR system (Laser Imaging Detection And Ranging). This system uses laser technology to accurately determine the prevailing wind direction and identify the optimal orientation of the wind turbines in order to get the best possible energy performance.

Ailes Marines also presented the Management and Monitoring Committee with the results of the environmental studies which show that the sound waves generated by drilling are compatible with the normal life cycle of the species of fish studied. As a result of these studies, the company has decided to abandon the pile-driving technique in favour of the drilling method for installing the piles.


Saint-Brieuc will bear the seal of Spain, since the jackets — (the platforms that support the offshore turbines) and the piles will be built entirely by Navantia-Windar, in Fene (A Coruña), where a 1,600 tonne caterpillar crane will be used for the final assembly, and Avilés (Asturias), respectively.

At €350 m this is the biggest offshore wind contract in the history of the shipyard, and it will create over 2,000 direct jobs and thousands of indirect ones.

The assembly work for the foundations has already begun following the arrival of the structural tubes at the ports of Ferrol and Brest. The final assembly of all the component parts will be completed at the Galician shipyard facilities.


The manufacture of the turbines, each 207 metres tall will be handled by Siemens Gamesa Renewable Energy (SGRE). They will be fitted with the latest direct-drive technology and their blades, almost 82 metros long, will sweep an area 18 % bigger than the previous model improving the annual energy production by 20 % compared to their predecessors.

The assembly of the towers, which will take around eight months, will be done on the new polder at the Port of Brest and will entail the creation of new industrial capacity funded to the tune of 11.8 million euros. The construction of this new plant will begin in early 2022, and it is set to be commissioned by the end of the same year.

 Marine substation

The marine substation has been awarded to a joint venture comprising Eiffage Métal and Engie Solutions. The former will undertake the engineering and construction of both the foundations and the platform that will house the transformers and other electrical gear, while the latter will handle their assembly and commissioning.

The structure supporting this substation comprises a foundation (jacket) 63 metres high and weighing 1,630 tonnes, and a platform 55 m long, 31 m wide and 23 m high, weighing approximately 3,400 tonnes. The substation will be completed at the beginning of 2022.

Iberdrola has awarded GE Renewable Energy Grid Solutions the supply and installation of the major electrical equipment for the substation. The company will take charge of the design, construction, installation and commissioning of the high-voltage electrical equipment, as well as the control and protection system for the substation. This will involve designing and manufacturing the 72.5 kV and 225 kV gas-insulated switchgear (GIS) at their factory in Aix-les-Bains (France). Commissioning tests for the electrical equipment in the offshore substation are expected to take place during 2022.

 Transport and installation

For its part, the Dutch maritime services company Van Oord will take responsibility for the transportation and installation of the 62 jackets and the marine substation. Van Oord will start work on the open sea in 2021 with the installation of the anchor bolts, for which it will launch its high seas support boat, Aeolus, specifically designed for the construction of offshore wind farms. It will be assisted by a second vessel from 2022.


As for the undersea cabling connection systems, these will be provided by the Prysmian Group, world leaders in the business of power cabling systems and telecommunications with whom Iberdrola has already worked on Wikinger and Vineyard Wind. They will install and commission 90 km of high-voltage 66 kV AC connection cables and three hubs with XLPE insulation.

Following tests carried out in summer 2020, Ailes Marines has confirmed that it will bury all the cables between the wind turbines, which is a giant step forward for navigational safety and for the continuation of fishing activity within the park. Delivery and commissioning are scheduled for the end of 2022.

 Communication and coordination

A consortium led by Atos - in partnership with SeaRenergy, a leader in engineering, marine solutions, QHSE and personnel services for the offshore wind industry - will be responsible for implementing critical communication solutions and ensuring maritime coordination activities.

Specifically, a maritime coordination centre will be set up in the coastal city of Pleudaniel (France) to coordinate, monitor and document all the movements in and around the construction area, 24 hours a day, seven days a week during the construction phase. They will also establish a unified critical communications platform that will enable the helicopters, ships and operational teams working on the offshore wind farm to communicate with each other and with the coordination centre, within and around the park.

Both systems will be retained after the construction phase and will support the wind farm throughout the operational phase, when all 62 turbines are working.

In addition, in order to inform inhabitants, in particularly sea users, Ailes Marines will soon provide an online information service regarding the works and will establish compensation measures for fishermen whose activity may be affected during the construction phase.