First Monopile Installed at RWE and TotalEnergies’ Dutch Offshore Wind Farm

Foundation installation has started at the 795 MW OranjeWind offshore wind farm in the Dutch North Sea, with the first of 53 monopiles now in place.

The foundations are being supplied by Sif and installed by Jan De Nul’s heavy-lift vessel Les Alizés . The installation campaign is expected to be completed by early 2027.

The project uses transition-piece-less (TP-less) monopiles, meaning the turbines will be bolted directly to the top flange of the monopiles, which are approximately 90 metres long and measure 8 metres in diameter. Secondary steel components such as the main access platform, internal cassette and boat landings will be mounted directly onto the monopiles in a separate installation campaign.

Les Alizés is loading the foundations at Sif’s terminal at Maasvlakte near Rotterdam and transporting them to the offshore site, where the monopiles are driven into the seabed with a hydraulic impact hammer.

To limit the impact of piling noise on marine life, Jan De Nul is using a bubble curtain around the installation site. The project will also carry out noise measurements outside the curtain to verify that sound levels remain within applicable limits, according to the developer, a joint venture between RWE and TotalEnergies.

The 795 MW OranjeWind (Hollandse Kust West VII) offshore wind farm is located 53 kilometres west of IJmuiden, in the Economic Exclusion Zone (EEZ) of the Netherlands in the North Sea and will consist of 53 Vestas V236-15 MW turbines.

Inter-array cable installation is scheduled to take place at the end of 2026, and wind turbine installation is planned for 2027. Jan De Nul’s jack-up installation vessel Voltaire will install the turbines, while the inter-array cables will be installed by DEME, which will also mount the secondary steel on the monopiles.

Once fully commissioned in 2028, OranjeWind is expected to generate enough electricity to supply the equivalent of approximately one million Dutch households annually.

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