Seagreen wind farm will be equipped with up to 114 MHI Vestas wind turbines. Credit: MHI Vestas Offshore Wind.
Seagreen Alpha and Seagreen Bravo will have a combined installed capacity of up to 1.075GW. Credit: Petrofac Limited.
The project will involve the installation of three 65km-long offshore export cables and three 20km-long onshore export cables. Credit: Nexans.

The 1.5GW Seagreen offshore wind farm project is being developed in the Firth of Forth Development Zone of the North Sea, Scotland, UK.

The project is owned jointly by TotalEnergies (51%) and SSE Renewables (49%), a subsidiary of SSE. TotalEnergies acquired a 51% share in the wind farm in June 2020. SSE Renewables is responsible for the development and construction of the wind farm and also serves as an operator of the wind farm.

Seagreen will become the biggest wind farm in Scotland and the world’s deepest fixed-bottom offshore wind farm, upon completion.

The Seagreen wind farm phase one plan originally involved the construction of two wind farms, Seagreen Alpha and Seagreen Bravo, with a combined installed capacity of 1.075GW. Alpha and Bravo were later amalgamated into the Seagreen 1 project.

Early works on the Seagreen 1 project began in January 2020. The first power at the project was achieved in October 2022.

The 114th final wind turbine was installed in June 2023. The wind farm is currently producing more than two-thirds of its total capacity and is expected to become fully operational in Summer 2023.

The wind farm is expected to generate 5,000GWh of clean energy a year, which will be sufficient to power approximately 1.6 million Scottish households. The operational life of the wind farm is expected to be 25 years.

The wind farm is expected to create up to 410 jobs. It will also offset two million tonnes of carbon dioxide emissions a year.

Seagreen offshore wind farm location

The Firth of Forth Zone is situated approximately 27km away from the Angus coastline. It covers an area of approximately 2,850km² in the outer Firth of Forth.

The neighbouring Seagreen 2 and 3 wind projects in the Firth of Forth Zone were renamed as Berwick Bank and Marr Bank wind farms, respectively, in 2020. The two projects have been combined to be developed as a single project, known as Berwick Bank Wind Farm, with a total capacity of 4.1GW.

Seagreen wind farm development details

The development rights of the project were received from the Crown Estate in 2010. The environmental approval for the Alpha and Bravo offshore wind farms was obtained in 2012.

The Scottish government granted consent for the development of phase one of the wind farm in October 2014.

In March 2018, Seagreen submitted an application to Marine Scotland, seeking modifications for the agreed capacity limits and to increase the combined installed capacity of two wind farms.

SSE Renewables took full ownership of the Seagreen wind farm with the acquisition of Flour’s 50% stake in the project in September 2018.

Seagreen Wind Energy secured a 15-year Contract for Difference from the UK Government for 454MW in September 2019.

The final investment decision for the wind farm was announced in June 2020.

The installation of the deepest fixed bottom jacket/foundations at a water depth of 58.6m was completed in April 2023. The foundation installation work was started in October 2021. The installation of turbines began in December 2021.

The Marine Licence application for the Seagreen 1A project was approved in December 2021. The project will allow for the connection of the remaining 36 turbines of the Seagreen project to the grid.

The Section 36C application to increase the capacity of the Seagreen project to 1.5GW was approved in October 2022.

Seagreen offshore wind farm project details

The Seagreen project will have 150 turbines, 114 of which have been already energised. Powering up the remaining 36 turbines and connecting them to the grid will increase the electricity generation capacity to 1.5GW.

The wind farm is equipped with three-bladed horizontal axis turbines mounted on monopile foundations.

The Seagreen 1 wind farm has 114 Vestas V164-10.0 MW wind turbine generators with a maximum height to the tip of the blade of 204m and a blade diameter of 164m.

The turbines were mounted on monopile foundations. Each monopile has a diameter of 10m and a length of 95m. The wind turbines are interconnected with up to 325km of inter-array cables.

Seagreen offshore wind farm power transmission

Montrose Port has served as the operations and maintenance base for the offshore wind farm for a period of 25 years. It mainly ensures safe clean energy delivery daily.

The electricity generated by the Seagreen turbines is transferred to landfall at Carnoustie through subsea export cables. It is then transmitted to a new substation at Tealing through 19km-long underground cables.

The Seagreen 1A project will be connected to the existing Scottish Power substation at Cockenzie in East Lothian.

A 110km-long export cable will carry the generated electricity from the wind farm to the landfall at Cockenzie.

Contractors involved

MHI Vestas Offshore Wind (MHI Vestas), now part of Vestas, was contracted to provide 114 wind turbines for the wind farm project in October 2019.

Petrofac signed a preferred supplier agreement with SSE Renewables for the Seagreen wind farm project in January 2020. The company was responsible for the design, supply and installation of high-voltage alternating current onshore and offshore substations, according to the agreement.

Subsea 7, an offshore energy company, was chosen to deliver the engineering, procurement, construction and installation (EPCI) services for the 114 wind turbine foundations and associated inter-array cables in June 2020.

SSE Renewables awarded a contract to Nexans for the supply of onshore and offshore export cables for the wind farm in June 2020. The contract included the design, manufacture and installation of three 65km-long offshore export cables and three 20km-long onshore export cables. Nexans used Aurora, a cable-laying vessel, for the installation of the cables.

Hellenic Cables, a submarine cable solutions provider, was contracted by Seaway 7 to design, manufacture, test and supply 66kV inter-array cables and associated accessories for the Seagreen wind farm in July 2020.

Seaway 7, the renewable business unit of Subsea 7, was appointed to perform the EPCI services. Saipem was subcontracted by Seaway 7 for the installation of the foundations in July 2020. Saipem used its Saipem 7000 vessel, a semi-submersible crane vessel, for the work.

Seaway 7 was also named as a preferred supplier for the Seagreen 1A project in June 2022. The contractual scope, which is yet to be finalised, may include engineering, fabrication, transport and installation of 36 foundations, procurement and installation of inner-array cables, as well as transportation and installation of the offshore substation.

MHI Vestas subcontracted Siemens Energy, an energy technology company, to provide 114 low-loss 66kV distribution transformers for the project in December 2020.

Ramboll, an engineering consulting company, provided detailed design services for the foundation sub-structures of the project. It was also chosen as the environment and consents manager for onshore transmission works for the Seagreen 1A project in December 2020.

Northern Marine Services, a Scotland-based marine inspection company, was chosen to support the delivery and installation of the wind turbine foundations of the Seagreen project from the Port of Nigg in June 2021.

Inland and Coastal Marina Systems UK received a contract to supply and install a new 30m pontoon at Montrose Port to serve the wind farm in August 2021.

Global Port Services, part of Global Energy Group, received a contract from Seaway 7 to provide storage, marshalling and logistics services for the 114 foundation towers.

The company also received a contract to provide site-enabling services for the pre-assembly construction of wind turbine components at the Port of Nigg in December 2022.

The Cathodic Protection Division of GIBCA group’s subsidiary Alico Industries supplied sacrificial anodes to provide cathodic protection to the substations and jacket foundations of the wind farm.

Norwegian offshore wind service vessel company Edda Wind was contracted to design and build the Edda Brint service operation vessel (SOV) for operations at the Seagreen wind farm. The SOV was hired for 15 years by Vestas to provide operation and maintenance services for the wind farm. Edda Brint arrived at Montrose Port in March 2023.