RWE has reached a major construction milestone at the Sofia offshore wind farm with the installation of the 100th and final steel monopile foundation structure.
All foundations are now in place for the 1.4GW offshore array located on Dogger Bank, 195km off the north-east coast of the UK.
This concludes the 14-month foundation installation campaign executed by Van Oord as part of a joint engineering, procurement, construction and installation (EPCI) contract for both wind turbine foundations and array cables.
RWE offshore wind chief executive Sven Utermöhlen said: “The successful completion of monopile installation at Sofia marks a significant milestone in the delivery of this complex offshore wind construction project.
“This achievement is a testament to the expertise, dedication, and collaboration of the entire RWE team and our partners. Sofia will play a critical role in contributing to the UK’s clean energy transition and reinforcing energy security.”
Sofia offshore wind farm is located in water depths of 20-35 metres and is RWE’s largest offshore project currently under construction globally.
Once fully operational, the generation output of all 100 of Sofia’s turbines will be equivalent to powering up to 1.2 million typical UK homes with electricity from wind energy.
RWE described the EEW-manufactured foundations as state of the art. Rather than using a monopile foundation topped with an overlapping separate transition piece, an extended single monopile is installed and secondary steel fitted offshore. RWE said this significantly reduces the total steel tonnage required to complete the project, saving on steel and associated energy resources.
The installation works started in May 2024 using Van Oord’s jack-up vessel Aeolus (pictured). The vessel underwent a project-specific upgrade to its crane system to achieve a 1650-tonne lift capacity, enabling it to handle Sofia’s heaviest monopiles.
Each of the steel cylinders will form a solid base for the 14MW Siemens Gamesa wind turbines, which are 252 metres tall. Half of these are being installed with recyclable blades. The first turbine was installed in March, with 27 completed so far.
During construction, Sofia deployed a full-scale bubble curtain noise abatement system for 34 foundations – a first for the UK. The technology, operated by Hydrotechnik Offshore, creates a barrier of bubbles that significantly reduces underwater noise during piling operations, helping to protect marine species in the Southern North Sea Special Area of Conservation (SAC).
The installation campaign was carried from the Port of Tyne – the primary storage and marshalling location for all the foundation components.
With foundation installation complete, Van Oord is now progressing the burial of approximately 360km of array cables, with completion expected later this year.