Heavy plate from Dillinger for
the French offshore wind farm
in Saint-Nazaire

The Saint-Nazaire offshore wind farm is the first offshore wind farm to be installed and operated in France. Its 80 wind turbines, with a capacity of 6 MW per turbine and a total output of 480 MW, are located between 12 and 20 km off the coast of the Loire-Atlantique region on a total area of 78 km² at depths between 12 and 25 meters. The planned annual production of 1,735 GWh corresponds to covering 20% of the electricity consumption of the Loire-Atlantique region, which is equivalent to the consumption of 700,000 inhabitants.

The wind turbines are 210 m high, of which at least 30 m are underwater, and weigh about 1,000 tons. They are spaced at intervals of one kilometer and are connected to each other by cables in clusters of six or seven. These are connected to a substation at sea, which is equipped with an electrical transformer that raises the voltage of the electricity for transport on land. The wind turbines stand on so-called monopile foundations. These are steel pipes with a very large diameter, whose length is twice the water depth at the site. As this varies between 12 and 25 meters off the coast of Saint-Nazaire, these monopiles are between 25 and 47 meters long and have a diameter of 7.5 meters. They are designed to withstand the adverse conditions of the Atlantic for at least 25 years, the normal lifetime of the park. On each monopile there is a transition piece that connects it to the tower. It is the yellow piece that can be seen directly above sea level. This is followed by the 81 m high tower that supports the nacelle (4 m). This houses the generator, where electricity is generated via the rotation of the rotor blades (75 m long), their profiled shape allows them to capture as much wind as possible.

For the monopiles on which this wind farm is based, Dillinger supplied approx. 76,400 t of large-format heavy plate in thicknesses from 20 to 135 mm.