Offshore Wind Farm Saint-Nazaire, France

In sets of four, the turbines were loaded on board of the jack-up vessel Vole au vent and transported 12 km offshore, where the 1,500-tonnes main crane of the vessel mounted them on top of monopile foundations. The installation of one turbine took approximately 24 hours, depending on the weather conditions, so each installation trip took about 5 days. On 1 April, the first turbine was loaded in the port. On 5 September, the 80th and very last turbine was successfully installed.  

The Saint-Nazaire Offshore Wind Farm will produce 20% of the French Department Loire-Atlantique’s electricity consumption needs and will contribute to achieving the target of 40% renewable energy by 2030 and carbon neutrality by 2050 in France.

Challenging soil conditions at the Banc de Guérande

Jan De Nul brought its dredging and offshore wind installation expertise together to develop a unique method of construction consisting of preparatory rock fragmenting operations.

The majority of the Saint-Nazaire turbines needed to be installed on an uneven rocky seabed. Since the self-elevating jack-up vessel Vole au vent needs a stable seabed to safely jack on, some additional rock fragmenting operations were required to prepare the seabed for jacking. In the summer of 2021, Jan De Nul’s ocean-going Cutter Suction Dredger Fernão de Magalhães performed these preparatory works. The dredger fragmented the seabed using her rotating cutter head to smooth the seabed that then allows the Vole au vent to perform jacking activities.