In mid-May, Herrenknecht’s Offshore Foundation Drilling (OFD®) technology will be used in the construction of the Noirmoutier wind farm off the French Atlantic coast. The mechanized drilling method developed by Herrenknecht and DEME installs foundations for large-diameter monopiles, and was used for the first time at the St. Nazaire wind farm in 2021 and 2022.
Offshore Foundation Drilling (OFD®) makes it possible to safely install foundations for wind turbines and other coastal infrastructure even in rocky seabed conditions. The technology opens up new terrain for offshore wind energy and the expansion of renewable energy sources.
For the new wind farm, OFD will be used to drill boreholes for 61 monopiles in the rocky Atlantic seabed between the islands of Noirmoutier and Yeu. Each monopile has a diameter of 7m and will serve as the foundation for one of the more than 200m high wind turbines.
The machine previously used at the Saint-Nazaire offshore wind farm in 2021/2022 was completely overhauled by Herrenknecht. The new project off Noirmoutier is subject to similarly challenging weather, sea and bottom conditions as off St. Nazaire. With water depths of up to 36m, the monopiles will be embedded in the rocky seabed.
The monopiles for the Noirmoutier wind farm will be installed by DEME, who jointly developed the drilling and installation method with Herrenknecht and are continuing their close collaboration on this second project. Herrenknecht supplies the drilling technology and provides specialized drilling personnel who are constantly on board the installation vessel in shifts during the project. DEME is responsible for the installation of the monopiles and the MODIGA (Monopile Offshore Drilling Installation and Grouting Aid). It serves as a drilling template and enables controlled lowering using a liner, which also stabilizes the borehole. The 73 drilled foundations for the Saint-Nazaire wind farm have already been installed using the mechanized drilling method for large-diameter monopiles developed by the two technology leaders as a world first. This reference project was fully completed entirely on schedule.
The drilling for Noirmoutier will be carried out with the 350 tonnes OFD machine also
used off St. Nazaire. It has a drilling diameter of 7,700mm and an impressive drive power. For the construction of the new wind farm project, the OFD machine was thoroughly overhauled by Herrenknecht, subjected to extensive functional tests with comprehensive test documentation and then transported back to Vlissingen, the home port of the installation vessel “Innovation”. In addition to overhauling the machines and reusing them in new projects, Herrenknecht’s sustainability concept includes using OFD drilling technology to keep the seabed largely intact and reduce noise emissions that are harmful to underwater fauna.
Installation of the monopiles will begin soon. Monopiles will be loaded onto the
installation vessel in the port of La Rochelle. After the drilling process, the monopile is
then inserted into the lowered liner, creating the foundation for a wind turbine. During
the installation period for the wind farm foundations, a team from Herrenknecht will
always be on board to control and maintain the OFD drilling machine.
After completion, the Noirmoutier windfarm will have a total output of 496MW and
generate around 1,900GW hours of electricity per year from, covering the needs
of 800,000 inhabitants.
PROJECT DATA PARC EOLIEN EN MER DES ILES D’YEU ET DE NOIRMOUTIER
- Client: Éoliennes en Mer des Îles d’Yeu et de Noirmoutier (EMYN), with shareholders Ocean Winds (joint venture of ENGIE and EDP Renewables), Sumitomo Corporation, la Banque des Territoires and Vendée Energie
- Contractor: DEME Offshore
- Application: Offhore wind power, monopiles, diameter 7 m
- Drilling depths: 15 – 27m
- Water depths: 19 – 36m
- Geology: mostly rock with hardness between 25MPa and 120MPa max.
DRILLING TECHNOLOGY
- Machine type: Herrenknecht OFD7700
- Drilling diameter: 7,700mm
- Weight: 350t
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