Subsea drilling XL-monopiles

Subsea drill for XL-monopile installation

SaINT-NazaIRE OFFSHORE WINDFaRM

DEME OffshOrE anD hErrEnknEcht havE signED an agrEEMEnt fOr thE fabricatiOn Of a subsEa Drill tO be deployed at the Saint-Nazaire offshore windfarm in France. This is the first windfarm in the world to use drilled XL-monopile foundations.

In 2019, a consortium including DEME Offshore and Eiffage Métal was awarded the EPCI contract for 80 foundations for the French windfarm. The scope includes the design, fabrication, transportation, and installation of the steel foundations. The 480MW Saint-Nazaire offshore windfarm, owned by EDF Renewables and Enbridge, will be located between 12km and 20km off the coast of the Guérande peninsula in western France.

Rocky seabed The XL-monopile foundations have to be installed on a difficult rocky seabed. DEME Offshore and Herrenknecht, one of the global leaders in tunnel boring machines, are fabricating an innovative tailor-made subsea drill specifically for the project. The subsea drill will be deployed from DEME Offshore’s installation vessel Innovation. “Installing drilled XL-monopiles is a new step forward in the offshore wind industry”, says Bart De Poorter, General Manager of DEME Offshore. “With this innovative solution, developed in partnership with Herrenknecht, we ensure that the installation is performed safely and efficiently in challenging marine conditions.”

Advantages “The Offshore Foundation Drilling (OFD) enables mechanised installation of

Photo courtesy of Ørsted/Sky Pictures.

monopiles, thus providing ecological and economic advantages compared to conventional methods”, comments Ulrich Schaffhauser, Member of the Board of Management of Herrenknecht. “We are proud that DEME relies on Herrenknecht’s solution, expertise, and know-how in the field of excavation technology. The DEME and Herrenknecht project teams cooperated very well, now we all are looking forward to the project’s realisation.”

i. deme-group.com i. herrenknecht.com i. parc-eolien-en-mer-de-saint-nazaire.fr

The subsea drill will be deployed from DEME Offshore’s installation vessel Innovation.

The 480MW Saint-Nazaire offshore windfarm, owned by EDF Renewables and Enbridge, will be located between 12km and 20km off the coast of the Guérande peninsula in western France.