RWE has reached a key construction milestone at its Sofia offshore wind farm with the installation of the 100th and final steel monopile foundation, marking the completion of the foundation phase for the 1.4 gigawatt (GW) project located on Dogger Bank, approximately 195 kilometres off the northeast coast of the UK.
The 14-month installation campaign was carried out by Van Oord under a joint engineering, procurement, construction and installation (EPCI) contract covering both turbine foundations and array cables.
Sven Utermöhlen, chief executive of RWE Offshore Wind, 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.”
The wind farm is situated in water depths ranging from 20 to 35 metres and represents RWE’s largest offshore project currently under construction worldwide. Once operational, the 100 turbines will generate enough electricity to power up to 1.2 million typical UK homes.
RWE described the EEW-manufactured foundations as “state of the art,” highlighting that an extended single monopile with secondary steel fitted offshore was used instead of the traditional monopile topped with a separate transition piece. The approach reduces steel tonnage requirements, saving material and energy resources.
Installation began in May 2024 using Van Oord’s jack-up vessel Aeolus, which was upgraded with a crane system capable of lifting 1,650 tonnes to handle the project’s heaviest monopiles. The 14 megawatt Siemens Gamesa turbines stand 252 metres tall, with half fitted with recyclable blades. The first turbine was installed in March, with 27 completed so far.
As part of environmental measures, Sofia deployed a full-scale bubble curtain noise abatement system during piling operations on 34 foundations, a first for the UK. The system, operated by Hydrotechnik Offshore, reduces underwater noise to protect marine species within the Southern North Sea Special Area of Conservation.
Foundation components were stored and marshalled at the Port of Tyne. With foundations now complete, Van Oord is advancing the burial of about 360 kilometres of array cables, expected to be finished later this year.
