Offshore construction begins on RWE’s Sofia offshore wind farm

Offshore construction has started on RWE’s 1.4 GW Sofia offshore wind farm on Dogger Bank in the central North Sea off the northeast coast of the UK.

The offshore works are kicking off with the laying of the first section of high voltage direct current (HVDC) export cable which will be done by Prysmian’s Leonardo da Vinci vessel.

Prysmian’s 170-metre-long vessel will operate out of the Middlesbrough Port and will lay two 130-kilometre sections of cable in parallel.

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 that were installed earlier this year. The cable will pass below the beach, sand dunes, and road before emerging at the landfall construction compound.

Leonardo da Vinci will then move away from the coast, laying the full length of cable along its set route towards the offshore wind farm, located 195 kilometres from the nearest point on the UK’s northeast coast.

Installation of two remaining 90-kilometre sections of marine export cable is planned for next year. 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.

“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,” said Sven Utermöhlen, CEO of RWE Offshore Wind.

Operations and maintenance activities for the site will be located at RWE’s new offshore wind operations base in Grimsby, which will also support Triton Knoll offshore wind farm and future projects.

The Sofia offshore wind farm will have a single offshore converter platform, with the electricity generated transported to landfall 220 kilometres away in Redcar, Teesside.

The project will feature 100 Siemens Gamesa SG 14-222 DD wind turbines scheduled to be fully commissioned in 2026. 44 out of 100 units will be equipped with 108-metre-long recyclable blades.

Onshore construction has been underway in Teesside since June 2021, to install 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, said RWE.

The ongoing offshore works will include the arrival of Sofia’s offshore converter platform, planned to make the journey from Batam, Indonesia, to the UK in 2024.

In addition, the start of installation of the 100 extended monopile foundations and array cables is scheduled for next year, according to the developer.

Once fully completed, the 1.4 GW offshore wind farm will be able to generate enough wind energy to meet the electricity needs of almost 1.2 million average UK homes.