Ørsted preparing seabed for Hornsea Three export cable

Preparation work for the installation of the Hornsea Three export cable is underway with boulder and debris relocation, and a geophysical survey starting this month, following the completion of UXO clearance work. An installation campaign to replace blanking plates from the horizontal directional drilling (HDD) ducts with bell-mouths is scheduled to begin in June.

Export cable installation is expected to start this year and be completed by 2027, according to information about the project shared last year when Ørsted awarded the contract for the installation work to Jan De Nul.

Under the contract, Jan De Nul is responsible for the seabed preparation, transport, installation, and protection of 350 KM of HVDC export cables and platform interlink cable connecting the offshore wind farm to the UK electricity grid.

As part of the seabed preparation work, a confirmed unexploded ordnance (cUXO) removal campaign along the export cable route was carried out last month.

Cable manufacturer NKT is in charge of the design, manufacturing, jointing, and termination of the export power cable system for Hornsea Three. The system will include two circuits with a route length of approximately 170 kilometers of 320 kV DC offshore cable, 50 kilometers of 320 kV DC onshore cable, as well as four circuits for a 1.5-kilometer route of 400 kV AC onshore cable.

The DC system will connect the wind turbines with the substation, while the AC cables will connect the substation to the national grid.

The first of the two offshore substations to be installed at the Hornsea Three offshore wind farm is currently on its way to Norway for final outfitting, after it sailed out from Thailand last month.

The Hornsea Three offshore wind farm, located approximately 160 kilometers off the Yorkshire coast, will comprise around 200 Siemens Gamesa’s 14 MW wind turbines and is expected to be operational in 2027.

Ørsted says that with the installed capacity of 2.9 GW, Hornsea Three is the largest single offshore wind farm in the world, as it was developed and will be built as a single project rather than a phased development.