SSE, Marubeni & CIP’s Floating Wind Farm in Scotland Could Have 270 Turbines and 6 Offshore Substations

March 17, 2023, by Adrijana Buljan

SSE Renewables, Marubeni and Copenhagen Infrastructure Partners (CIP) have submitted the Environmental Impact Assessment (EIA) Scoping Report for the array area of their Ossian floating wind farm to Marine Scotland. According to the report, the wind farm could have up to 270 wind turbines and six offshore substations.

The consortium won the development rights for the Scottish site last year. The site, covering 858 square kilometres of seabed in the Firth of Forth off the Angus Coast, was one of the largest lease areas offered by Crown Estate Scotland in the ScotWind leasing round in 2022.

The installed capacity of the floating wind farm was initially said to be 2.6 GW. At the end of last year, the developers announced that they had identified an increase in the potential overall project capacity of 1 GW.

With a total generation capacity of 3.6 GW, the Ossian floating wind farm in Scotland is said to be the largest project of this kind in development worldwide.

The scoping report, which marks the first formal submission in the EIA process for the project, outlines the key technologies that are currently under consideration for the 3.6 GW floating wind farm’s array, including wind turbines, offshore substations, and inter-array and interconnector cables.

Ossian is planned to comprise up to 270 wind turbines, but the final number will depend on the rated output of the wind turbine model that will be used. The model will be chosen when the final project design is developed,

The scoping report also states that the maximum rotor blade diameter is expected to be up to 350 metres.

For the floating wind turbine foundations, the consortium is considering either semi-submersible or Tension Leg Platform (TLP) structures and three mooring configurations; catenary, semi taut and taut mooring lines. Anchoring options currently under consideration include driven piles, and a number of different embedded anchor types, including suction piles, Drag Embedment Anchors (DEA) and VLA, with up to nine anchors required per foundation.

Floating foundations might not only be used for the wind turbines, but also for Ossian’s offshore substations.

The floating wind farm is planned to have six offshore substation platforms, which are expected to be installed on fixed substructures, however, the Ossian partners are also considering floating substructures at this time.

Nevertheless, according to details from the scoping report, the offshore substations will most likely be installed on eight-legged jacket foundations.

The scoping report for the Ossian array area was submitted on 9 March and Marine Scotland launched the formal consultation process on 16 March.

SSE, Marubeni and CIP will submit a separate EIA scoping report for the proposed offshore and onshore export cable corridor(s), including onshore substation at the proposed landfall location(s), once relevant information is available following the conclusion of the ongoing Offshore Transmission Network Review (OTNR) and National Grid Holistic Network Design Follow Up Exercise (HNDFUE) review, according to the consortium.

The 3.6 GW Ossian floating wind farm is planned to be up and running before the end of the decade.

If the project is built up to a capacity of 3.6 GW, it would be capable of powering almost 6 million Scottish homes and offsetting around 7.5 million tonnes of carbon emissions each year, according to information about the project SSE shared earlier.