RWE, one of the world’s leading companies in offshore wind, has achieved a major milestone in the delivery of its flagship Sofia Offshore Wind Farm with the successful installation of the Offshore Converter Platform (OCP) which converts high voltage alternating current (AC) to high voltage direct current (DC) This critical infrastructure sits at the heart of the wind farm and is RWE’s first offshore deployment of High Voltage Direct Current (HVDC) technology. Its successful installation keeps the 1.4 gigawatt (GW) project on track to be fully operational in 2026. Once fully operational, Sofia will be capable of generating enough electricity to power approximately 1.2 million typical UK homes.
The massive OCP structure, constructed over two and a half years and requiring more than 13 million hours of work, was loaded out from Batam Yard in Indonesia and transported to the North Sea. It is understood to be the largest offshore wind converter platform of its type in the world, and its installation is a testament to the successful collaboration between RWE and its partners, GE Vernova and Seatrium. The use of HVDC technology enables high efficiency transmission of the wind farms electrical output, minimising power losses along the 220km cable route to shore.
Sven Utermöhlen, CEO RWE Offshore Wind: “The successful installation of the OCP, the largest converter platform of its kind in the offshore wind industry, is a proud moment for RWE and everyone involved. This project not only highlights our commitment to leading the way on offshore wind, but demonstrates the scale and complexity of what can be achieved when we all work together.”
The installation was carried out by Heerema, using its Sleipnir heavy lift vessel as a subcontractor to the GE Vernova/Seatrium consortium responsible for the OCP. The platform, equivalent in height to an 11-story building and weighing over 13,000 tonnes, was lifted onto the jacket structure, marking the largest lift in offshore wind history.
The jacket structure, a welded tubular space frame, was first placed to support the topside facilities, which include supports for conductors, risers, and the topside itself. The topside, now securely in place, will play a crucial role in converting the electricity generated by the wind turbines and transmitting it to the onshore connection substation.
Once operational, the Sofia Offshore Wind Farm, located on Dogger Bank, 195 kilometres off the northeast coast of the UK, will transmit low-carbon electricity generated from 100 Siemens Gamesa 14 megawatt (MW) wind turbines. The energy will be carried through subsea export cables to landfall in Redcar, Teesside, 220 kilometres away.
The turbines, featuring the most advanced offshore wind technology, stand 252 meters tall and are equipped with 108-meter carbon and fibreglass blades, with a 222-meter diameter rotor sweeping an area of 39,000 m². Notably, 44 of the project’s 100 turbines will feature recyclable blades, further enhancing the project’s sustainability.
Operations and maintenance activities for Sofia will be managed from RWE’s new offshore wind operations base, the ‘Grimsby Hub,’ which also supports RWE’s Triton Knoll Offshore Wind Farm. RWE is also developing in the region its two Dogger Bank South projects which, together, would have a potential installed capacity of around 3 GW.
As RWE’s largest offshore wind farm to date, Sofia represents a critical component of the UK’s renewable energy future, setting new standards for innovation, sustainability, and collaboration in the offshore wind industry.
Pictures of the OCP installation (credit: RWE) are available at the RWE Media Centre.
