The Groix & Belle-Île pilot wind farm was selected as winner of the ADEME’s EOLFLO call for projects. It is overseen by the company Ferme Eolienne Flottante de Groix & Belle-Île which brings together EOLFI, CGN Europe Energy, and the Caisse des Dépôts et Consignation. The pilot farm is a floating technology demonstrator that comprises four wind turbines that will generate around 90 GWh, equivalent to electricity consumption levels for 46,000 inhabitants per year, meaning nearly 80% of the town of Lorient. The pilot farm will be connected to the grid at the Kerhellegant substation in Plouharnel. The project is backed by Investissements d’Avenir via the ADEME’s ‘demonstrators for ecological and energy transition’ scheme.


After consulting with all stakeholders (local councillors, governmental departments, coastal workers, socio-professional and association representatives), the Conférence Régionale Mer et Littoral de Bretagne (Brittany’s Regional Sea & Coast Conference) and the ADEME selected the Groix & Belle-Île floating wind site. The Groix & Belle-Île floating wind turbine site emerged as the ideal sector in which to establish the pilot farm for the following reasons:

  • The sector is representative of sea conditions across most of the global floating wind turbine market
  • Existing infrastructures in western France capable of accommodating the site (Lorient for maintenance, Brest for part assembly, etc.)
  • Proximity to the coastline for ease of maintenance

In addition, renewable marine energy projects such as the Groix & Belle-Île and Saint-Brieuc floating wind turbine sites will help secure Brittany’s electricity supplies. The site selected for the four wind turbines is located in the centre of a 17 km² sector, approved by the Conférence Régionale Mer et Littoral de Bretagne. This more restricted perimeter offers greater compatibility with sea uses and reduces the impact on the marine environment.

Technical choice

The wind turbine float developed by Naval Energies comprises four cylindrical steel columns designed to ensure buoyancy for the concrete baseplate that stabilises the structure. This float is anchored to the seabed with six anchor lines to hold the wind turbine in place and prevent drifting. The wind turbine developed by GE RENEWABLE ENERGY has a capacity of 6 MW equivalent to the electricity needs of 5,000 households. Several technological innovations have been implemented to adapt the wind turbine to a floating environment.

Electrical connection

The corridor to be used to connect the wind farm is due to be approved on March 22nd, 2017, during a plenary meeting to be chaired by the Prefect of Morbihan and attended by all those involved in this collaborative project.

The electricity generated by the wind turbines will be injected into the grid at the Kerhellegant substation in the local council of Plouharnel. The landing for the underwater connection will be built in the Kerhillio area in the town of Erdeven, around 4km away from the existing Kerhellegant substation.

The Groix & Belle-Île floating wind site will be connected to the public electricity transmission network by underwater and underground connections.

Underwater connection

The underwater connection features a single tri-cable submarine cable covered by a protective sheath. Depending on the nature of the seabed, and to ensure complete safety and security throughout works, the latter will be embedded in marine sediment where possible. If embedding is not possible, the connection may be protected with rockfill, concrete slabs or cast-iron ballasting shells.

Underground connection

The underground connection will run from the landing manhole and comprise three separate cables in sheaths, buried in underground trenches measuring around 1.50 metres deep.

Grid connection and environment

The corridor chosen for the underwater cable measures around 28km long. Studies conducted in July 2018 established a route that circumvents rocky areas leading to the coast, and should make it possible to embed the cable all the way up to the landing point on Kerhillio beach. Embedding is a cable protection technique with minimal impact on the environment. It also has the advantage of ensuring fishing activity can be maintained across the connection perimeter. The manhole (connection point between the underwater and underground cables) will be set up beneath an area that has already been built over, around the beach’s car park. The underground connection will extend over approximately 4.5km to the RTE station at Kerhellegant, and will mostly follow existing roads, therefore having no impact on the natural environment.





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