Installation of 80 wind turbines complete in Saint Nazaire

The installation of the Saint Nazaire offshore wind farm’s 80 turbines, which began in mid-April, is now complete. This 480 MW park is France’s first offshore wind farm and will be fully operational by the end of the year.

This week, for the first time in France, electrons were produced from offshore wind turbines installed off Saint-Nazaire. Located 12 km off the peninsula of Guérande, in the Loire-Atlantique region, the wind farm will supply the region with equivalent to the annual domestic consumption of 700,000 people, or around 20% of its energy needs. Teams from the Réseau de Transport d’Electricité (RTE) have now connected the wind farm to the national grid.

Saint Nazaire Foundations

Stored in the port of La Rochelle, the wind turbine foundations were transported, 3 by 3, and installed, thanks to the Innovation ship, on the Guérande bank site between May 2021 and May 2022. The foundations measure 7 metres in diameter. These steel tubes are laid on the seabed, between 12 and 25 m deep, by ramming or drilling, with little use of cement. The yellow transition pieces that emerge 25 metres above the sea to accommodate the wind turbines rest on the foundations. The Vole au Vent, a vessel owned by Jan de Nul Group, was in charge of the transport and installation of the wind turbines at sea. It transports the components of 4 wind turbines on each shuttle, i.e. 4 masts, 12 blades and 4 nacelles.

Laying the Cables

The Olympic Triton is the vessel in charge of installing the cables linking the wind turbines to the offshore electrical substation. Since the Guérande Bank is rocky, the cables, measuring 137 to 148 millimetres in diameter, are laid directly on the seabed and protected by cast iron half-shells. Bags of ruble are used to weigh the cable in certain places. These cables, made by Prysmian, carry 33kV alternating current. By the end of 2021, a quarter of the cables (20 out of 80) had been installed. After a winter break, the installation resumed in mid-March 2022 to finalise the connection of the wind turbines of the park.

The Substation

The Sea Installer vessel installed the 4 piles that housed the jacket of the 2100-tonne electrical substation. The Rosetti Marino Group teams worked on the elaboration of this yellow metallic structure on which the electrical substation was placed. This structure is the nerve centre of the future electrical system. It will collect the electricity produced by the 80 wind turbines and transform it to send it to shore via 2 submarine and underground cables to the electrical substation located in Prinquiau.

Wind Turbines

General Electric assembled the nacelles and generators for the wind turbines in Montoir-de-Bretagne, in the Pays-de-la-Loire region. Once ready, the nacelles were transported by land and sea to the pre-assembly site in Saint-Nazaire. From there, they are loaded, 4 by 4, on the Vole au Vent of Sodraco (a subsidiary of Jan de Nul) and installed at sea from April 2022 on. The turbines are 6 MW GE Haliades and measure 150 metres in diameter. The park’s maintenance base is in la Turballe.

EDF Renewables

The wind farm is owned by the EDF Renewables consortium and EIH S.à r.l. (a subsidiary of Enbridge Inc. and CPP Investments). RTE is responsible for bringing the energy produced by all the French offshore wind farms to shore, which to date represents a portfolio of 17 projects spread over all of France’s coastlines, with a total capacity of more than 10 GW and an investment of around 8 billion euros.

EDF Renewables and its partners are actively participating in this opportunity, with four offshore wind projects under construction off Saint-Nazaire, Fécamp (500 MW – 71 wind turbines), Courseulles-sur-Mer (450 MW – 64 wind turbines) and Port-Saint-Louis-du-Rhône, and one under development off Dunkirk (600 MW – about 40 wind turbines). These projects should mobilise several thousand jobs and supply hundreds of thousands of people with electricity by 2027!

Author: Emma Dailey

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