Singapore’s Sembcorp Marine has recruited Iv-Offshore & Energy to work on the high-voltage direct-current (HVDC) offshore converter platform for RWE Renewables’ Sofia offshore wind farm in the UK.

Sembmarine’s workscope includes the design, construction, installation and commissioning of the OCP. The Netherlands contractor will provide engineering and procurement services.

The platform comprises a 10,000-tonne topsides and a 7000-tonne jacket foundation structure piled into the seabed 220 kilometres offshore. Iv-Offshore said it would be the most powerful and most remote OCP ever built.

Iv-Offshore will be Sembmarine’s engineering subcontractor for the balance of plant installation and will provide detailed design for the topsides and jacket and the procurement of topsides auxiliary equipment.

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Sembmarine and GE Renewable Energy’s Grid Solutions earlier this year landed the contract, worth around £600 million (US$826 million), to supply the HVDC electrical transmission system for the Sofia wind farm.

Delivery delay

Iv-Offshore on Wednesday said that Sembmarine is slated to start fabrication of the OCP at its yard on Batam Island, Indonesia, before the end of September, while offshore installation is scheduled for completion by the end of 2024.

This suggests a delay to the original timeline as Sembmarine, when awarded the lead contact in March, said delivery and offshore installation would be in 2023.

Last July, GE and Sembmarine began early design work for the project after being selected as the preferred supplier of the HVDC electrical transmission system that represents Sofia’s second-largest contract.

“The 1.4-GW Sofia project is our first to use the HVDC technology, which was selected to maximise the wind farm’s export capacity from a location so far from shore,” RWE Renewables chief operating officer Sven Utermohlen earlier said.

“We are delighted to be working with such a strong pairing on the delivery of this flagship project located on the remote Dogger Bank, in the middle of the North Sea.”

Sembmarine has already lined up Dutch contractor Heerema Marine Contractors to transport and install the Sofia OCP.

Heerema will install the platform using its semi-submersible crane vessel Sleipnir, which has previously performed work for the Hollandse Kust and Hornsea 2 offshore wind farms.

The 1.4-gigawatt Sofia wind farm, to be located off the north-east coastline of the UK, will power the equivalent of nearly 1.2 million homes, making it one of the largest offshore wind farms in the world.