The Korsnäs Offshore Wind Farm is the first major offshore wind project in Finland. The project is planned to be developed in the open sea area near Korsnäs.
It would be developed by state-owned enterprise Metsähallitus and Swedish energy company Vattenfall.
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In December 2022, Metsähallitus, which is responsible for the land and water areas of the country, selected Vattenfall as a partner for the development and operation of the wind farm through an international offshore wind tender.
The wind farm will have a maximum capacity of 2.5GW. It is expected to become operational in the 2030s.
Once operational, it will produce 7-Terawatt Hour (TWh) of electricity per year. This is equivalent to the power consumption of approximately 350,000 electrically heated households.
The project will entail an estimated investment of €2bn-3bn.
Korsnäs Wind Farm Location
The Korsnäs Offshore Wind Farm will be located in the Gulf of Bothnia (Pohjanlahti) on a public water area managed by Metsähallitus.
The project will be situated approximately 15km off the coast of Korsnäs.
The site is 13km from Blacksögrundet in Närpiö Municipality, 24.8km from Bergö Fishing Harbour in Maalahti Municipality, and 16.3km to Storkorshamn in Korsnäs.
The wind turbines would be located at water depths of 10-30m.
The wind farm will cover a total area of 220km2 in an area meant for wind power production in the Maritime Spatial Plan.
Korsnäs Offshore Wind Farm Background
Metsähallitus submitted a planning initiative for the project development to the Korsnäs Municipality in November 2020. Initially, the project was expected to have an annual production capacity of around 5,000-Gigawatt Hour (GWh) enough to power approximately 250,000 individual households with electric heating.
After surveys, the project site was moved further south initially. It is located much further from the Kvarken World Heritage Site, fish spawning grounds, and nature reserves.
In June 2021, Metsähallitus commenced the Environmental Impact Assessment (EIA) of the wind farm.
In December 2022, Vattenfall entered into a joint venture with Metsähallitus to build and operate the offshore wind farm.
The two entities agreed to expand the Korsnäs Offshore Wind Farm project in November 2023.
The project site was expanded by 5,400ha to 27,400ha, under the new regional plan of 2023. The plan would increase the planned 1,300MW production capacity towards 2GW.
Korsnäs Offshore Infrastructure
The project will consist of up to 150 wind turbines. The wind turbines will have a maximum height of 350m and a maximum unit power of 25MW.
The wind turbines will be connected via seabed cables. The cables will transfer the electricity from the wind turbines to the mainland via one or two marine power stations.
The power stations will be separated by an estimated distance of 1-2km. On the mainland, a substation would be developed near the landing point of the sea cables.
The sea cables would either end at the Korsnäs area in the Västanpåsidan area or the Svartkärri area, the area north of the Storkors fish harbour or the fish harbour area.
Power Transmission Details
At landfall of the sea cables, a power station is expected to be built.
Electricity will be transferred from the station via overhead lines to the Fingrid’s substation located towards the north in Tuovila, Mustasaari and/or Åback Power Station in Kristiinankaupunki towards the south.
One or two overhead lines with a maximum voltage of 400kV will transfer the electricity to the main grid.
A total of 12,400kV overhead line options would be considered. There are five options planned in the direction of Tuovila (SVE1), four in the direction of Åback (SVE2).
Three routes between Tuovila and Åback routes branching off to Tuovila and Åback (SVE3) are also under consideration.
Korsnäs Offshore Wind Farm Contractors
Arctia and GEOxyz were awarded a contract in July 2024 to undertake a geophysical research works necessary for the engineering of the project.
The scope of the contract includes mapping of 280km2 project area and two alternative corridors for the export cables.
Arctia will deploy its Kaiku and Keila I survey vessels to map the seabed morphology. This will be followed by the deployment of GEOxyz’s 55m Geo Ocean VI, which will conduct a 2D Ultra-High-Resolution-Seismic (UHRS) survey to obtain knowledge on the sub-seabed geology up to 100m below seabed.
Ernst & Young (EY) Corporate Finance acted as the financial advisor for Metsähallitus in the transaction with Vattenfall and conducted a competitive international auction process.
AFRY Finland Oy is the main consultant of the Environmental Impact Assessment (EIA) for Metsähallitus’ Korsnäs offshore wind farm. Alleco Oy, a subcontractor of AFRY Finland Oy, conducted the surveys regarding the spawning of Baltic herring.
