Jan De Nul Installs All Monopiles at 1.1 GW Thor Offshore Wind Farm

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All 72 monopile foundations have been installed at RWE’s Thor offshore wind farm in the Danish North Sea.

The monopiles are around 100 metres in length and weigh up to 1,500 tonnes each. The units were shipped from the heavy-lift terminal in Eemshaven, in the Netherlands, to the Thor construction site in the Danish North Sea.

The installation of the monopiles, delivered by Dajin Offshore and EEW SPC, was completed by Jan De Nul with their heavy-lift vessel Les Alizés . The first foundation was installed in April 2025.

Rather than using a monopile foundation topped with an overlapping separate transition piece, extended single monopiles were installed, and secondary steel structures, including boat landings, will be fitted offshore.

Secondary steel structures for the Thor foundations are being handled from the Danish Port of Thyborøn, and installation works will be completed later this year. The control centre for managing marine logistics and traffic throughout the offshore construction phase is also based in Thyborøn.

To protect monopiles from the harsh conditions at sea until the turbine towers are mounted next year, reusable hard covers will be installed.

The installation of the 72 Siemens Gamesa SG 14-236 DD turbines is scheduled to be carried out from the Port of Esbjerg, starting in 2026. Of the 72 turbines, 40 will feature recyclable rotor blades , and 36 turbine towers will be manufactured with a significantly lower carbon footprint than usual, according to the developer.

The 1.1 GW Thor offshore wind farm is expected to be fully operational in 2027, when it will be capable of producing enough green electricity to supply the equivalent of more than one million Danish households.

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