The Inch Cape offshore wind farm being developed in the North Sea offshore Scotland, UK, will have a capacity of 1.1GW. It is anticipated to be one of the largest offshore wind farms in the country.
The project is being implemented by Inch Cape Offshore, a joint venture between Energy for Generations (ESB), Ireland’s pre-eminent energy company; and Red Rock Power, an Edinburgh-based investor, owner, and operator of renewable energy projects.
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The project was awarded a contract for difference (CFD) in July 2022 and concluded its onshore enabling works in October 2023. The principal civil engineering works commenced in early 2024.
Inch Cape will make a considerable impact on the UK’s offshore wind objectives and is expected to generate sufficient green energy to supply more than half of the homes in Scotland.
Inch Cape project location
The Inch Cape offshore wind farm is located approximately 15km to 22km off the Angus coastline in the North Sea at water depths ranging between 45m and 55m.
The project covers a total development area of approximately 150km².
Inch Cape offshore wind farm details
The Inch Cape offshore wind farm will comprise 72 units of V236-15.0MW wind turbines from Vestas.
The V236-15.0MW turbines have a rotor diameter of 236m (774.27ft) and a swept area of 43,742m² (470,834.96ft²). The turbine blades measure 115.5m in length, enabling a capacity factor surpassing 60%.
The turbine design incorporates a medium-speed gearbox and an aerodynamic brake with full blade feathering and three pitch cylinders.
The project will feature XXL monopiles, tailored for the latest generation of offshore wind turbines. The monopiles will each have a maximum diameter of 11.5m, a length of 110m, and weigh up to 2,700t. An innovative hybrid structure was developed for the project by Vysus, which merges the steel jacket with a concrete gravity-based structure (GBS), negating the need for piling.
The fabrication of the monopiles is scheduled to start in late 2024, with delivery to the project site expected in late 2025.
Power transmission
The project will incorporate an offshore transformer module (OTM), which will be equipped with an array of critical components. These include two 545MVA main transformers, two 500kVA auxiliary transformers, a pair of 220kV GIS container modules, and two 66kV GIS container modules. All these elements are to be installed on decks mounted atop a jacket foundation strategically positioned at the heart of the offshore wind farm.
The generated power will be transmitted via two export cables over a distance of 85km to a newly constructed substation at Cockenzie, East Lothian, where it will enter the national transmission system.
The export cables are set to make landfall along the Firth of Forth coastline in East Lothian, subsequently connecting to a brief onshore export cable section, which will link to the newly constructed 220/275kV substation located at the site of the former Cockenzie power station.
From the substation, power will be transmitted approximately 300m underground to the existing Scottish Power Energy Networks (SPEN) 275/400kV substation at Cockenzie, where it will be integrated into the national transmission system.
Contractors involved
Boskalis signed an exclusive pre-construction agreement (PCA) for the Inch Cape offshore wind farm project in January 2019. The scope of work includes transportation and installation of the wind turbine foundations, offshore substation and cables.
Cadeler, an offshore wind farm construction company, was contracted in June 2024 to install the 72 wind turbines for the project. The installation contract is valued at up to €130m ($138m) and is expected to commence in the fourth quarter of 2026.
Siemens Energy and Iemants, a subsidiary of Smulders, were selected to supply and construct the onshore and offshore substations. Smulders (Iemants) subcontracted Eastgate Engineering in July 2024 for the electrical and mechanical installation on the OTM.
Lloyd’s Register Engineering provided impartial certification services to ensure compliance, offer assurance, and mitigate risks for the successful execution of the project.
Vysus Group, an engineering and technical consultancy, provided a steel jacket design with optimised transition piece concepts for wind turbine generator installations and alternative bracing arrangements.
Their responsibilities also included the structural design of steel-framed topsides and jacket substructures for offshore substation platforms, alongside a review of the third-party concrete GBS.
Vestas secured the contract to supply wind turbines for the wind farm in September 2022, which included a 15-year operations and maintenance (O&M) agreement.
Inch Cape Offshore signed capacity reservation agreements with Dajin Offshore Heavy Industry (Dajin Offshore) and Guangzhou Wenchong Shipyard Heavy Industry (GWSHI) for the supply, fabrication and delivery of monopile foundations.
The main civil works for the onshore transmission infrastructure are being undertaken by civil engineering contractor Careys.
RJ McLeod, a civil engineering company, completed the enabling works in October 2023 for the onshore infrastructure.
