Offshore construction has officially started at RWE’s 1.4 gigawatt (GW) Sofia Offshore Wind Farm to install essential subsea cable infrastructure from the UK’s northeast coast to the wind farm site on Dogger Bank in the central North Sea.

Cable contractor Prysmian’s high-tech Leonardo da Vinci vessel will lay the first section of high voltage direct current (HVDC) export cable, ready to transport green electricity from the wind farm back to the UK coast and ultimately into the UK transmission network.

The work marks a significant milestone for the project, with Sofia representing a more than £ 3 billion investment in the UK’s energy infrastructure by RWE. The wind farm will significantly contribute to the country’s net zero targets and be capable of generating enough clean electricity equivalent to meeting the needs of over 1.2 million typical UK homes.

Sven Utermöhlen, CEO RWE Offshore Wind: “Sofia is RWE’s largest renewable construction project to date, and its furthest from shore. The project is setting new standards in terms of addressing innovation, sustainability, and engineering challenges. The laying of the first section of export cable represents the culmination of 13 years of planning, preparation, and diligence, as well as a huge amount of support from suppliers and stakeholders alike. Building a project of this size and scale is a great opportunity to demonstrate our expertise in delivering offshore wind energy around the globe.”

Sofia Offshore Wind Farm is located on Dogger Bank, 195 kilometres from the nearest point on the UK’s northeast coast. It will have a single offshore converter platform, with the electricity generated transported to landfall 220 kilometres away in Redcar, Teesside.

The wind farm will use 100 Siemens Gamesa 14 megawatt (MW) offshore wind turbines (SG 14-222 DD), the most advanced offshore wind turbine technology available, and is scheduled to be completed by the end of 2026. Forty-four of the project’s 100 turbines will be equipped with recyclable blades. Operations and maintenance activities for the wind farm will be located at RWE’s new offshore wind operations base ‘Grimsby Hub’, which will also support Triton Knoll Offshore Wind Farm and future projects.

Prysmian’s 170-metre-long vessel will operate out of the Port of Middlesbrough and lay two parallel 130-kilometre sections of cable. It will start its cable laying work from just off the Teesside coast between Redcar and Marske-by-the-Sea. One end of each of the two sections of subsea cable will be pulled underwater from the vessel through cable ducts installed earlier this year. The cable will pass below the beach, sand dunes and road before emerging at the landfall construction compound. The cutting-edge vessel will then move away from the coast, laying the full length of cable along its set route towards the offshore wind farm. 

Installation of two remaining 90km sections of marine export cable is planned for 2024. By late 2024, Leonardo da Vinci will have laid four sections of ±320kV HVDC marine export cables with XLPE insulation, totalling 440 kilometres plus the accompanying communications cables.

Onshore construction has been underway in Teesside since June 2021 to construct the project’s onshore converter station and cable corridor. The laying of the first sections of export cable marks the start of a three-year offshore construction phase.

The ongoing offshore construction works will include the arrival of the project’s offshore converter platform, which is due to journey from Batam, Indonesia, to the UK in 2024. Also planned for next year is the start of the installation of the 100 extended monopile foundations and array cables.

RWE is the UK’s largest power producer and has ambitions to invest up to £15 billion gross in new green technologies and infrastructure in the UK by 2030.

Tom Glover, RWE’s UK country chair: “RWE has 10 offshore wind farms already operating around the UK and is a leading partner in the generation of clean energy that will help ensure security of electricity supply. This major construction milestone at Sofia further demonstrates our enviable expertise in offshore wind, which has been pioneered over 20 years in the UK. And the UK remains of significant strategic importance to RWE. We are continuing to drive our ambition to grow green through a strong future development pipeline, which will play a key role in delivering our own and the country’s future net zero ambitions.”

RWE has a strong UK pipeline and is involved in four of the UK’s seven offshore wind extension projects, plus two Round 4 Dogger Bank South projects. The company is also exploring offshore floating wind projects, including in the Celtic Sea region.

Image source: Courtesy of RWE

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