Suomen Hyötytuuli, one of Finland's longest-running wind companies, announced in March 2024 that it would split itself in three. Nobody new is buying in. The same eight Finnish energy companies will own all three pieces. A demerger that changes no ownership still changes something, and the clue is which project got a company of its own.
Key takeaways
- Suomen Hyötytuuli announced on 8 March 2024 a full demerger into three companies: Suomen Hyötytuuli Oy, Tahkoluoto Offshore Oy and Arenso Oy, with completion planned by the end of September 2024.
- After the demerger, Suomen Hyötytuuli Oy owns the existing onshore wind farms and the current Tahkoluoto offshore wind farm, Tahkoluoto Offshore Oy owns the Tahkoluoto demonstration and extension project, and Arenso Oy provides wind energy life-cycle services to both.
- All three companies are owned by Suomen Hyötytuuli's existing shareholders: Helen (through Oy Mankala Ab), Alva-yhtiöt, Lahti Energia, Lappeenrannan Energia, Pori Energia, Tampereen Sähkölaitos, Turku Energia and Vantaan Energia, which also take the power.
- At the time of the demerger Suomen Hyötytuuli had seven operating wind farms in Finland totalling 225 MW, three under construction totalling 412.6 MW and nine projects in development, producing about 750 GWh a year.
- Enerdatics records the Tahkoluoto Extension offshore wind farm at 700 MW, with an investment of $2.57 billion, financial close expected in mid-2027 and operation in 2030.
What does a demerger change if the owners stay the same?
It changes what can be sold, and to whom. A demerger splits one company into several, each with its own assets and its own balance sheet. The shareholders end up holding the same economic interest, just in more than one company.
Before the split, anyone wanting a stake in Suomen Hyötytuuli's offshore ambitions had to buy into its onshore fleet and its service business as well. After the split, the offshore extension sits in its own company. A partner can invest in Tahkoluoto Offshore without touching the onshore farms.
The company's own explanation points the same way. It said the demerger would allow cost-efficient and flexible use of resources and wind energy expertise, and would open up possibilities for further development of ownership structures and investment partnerships. That is language about bringing in new capital later, not about the eight owners on day one.
Why does the offshore project need its own company?
Because of its size. Enerdatics records the Tahkoluoto Extension at 700 MW, with an investment of $2.57 billion and expected output of 2,600 GWh a year. That single project is larger than the 637.6 MW the whole company had operating and under construction when the demerger was announced. Its expected output is more than three times what the existing fleet produced.
A project that large is a different kind of undertaking from an onshore wind farm. Suomen Hyötytuuli knows the site. It built Finland's first offshore wind turbine at Tahkoluoto, near Pori, in 2010. In August 2017 it commissioned the Tahkoluoto wind farm, described as the world's first offshore wind farm designed specifically for icy conditions. Experience is not the same as capital, however, and $2.57 billion is a lot to ask of eight Finnish energy companies on their own.
The onshore side has its own heavy programme. Enerdatics records the Siikajoki wind project at 235 MW, with an investment of $345.4 million and operation from January 2025. Oosinselkä, at 93 MW, began operating in October 2024 and Alajoki Peuralinna, at 90 MW, in April 2025. Two further onshore projects, Kokkoneva at 400 MW and Korpi-Matti at 110 MW, are at an early stage. Keeping all of that in one company alongside a multi-billion offshore build would have tied the two programmes together.
What is Arenso for?
It holds the know-how. Suomen Hyötytuuli has taken full life-cycle responsibility for its wind farms since it was founded in 1998, from development and construction to production, maintenance and eventual dismantling. It erected Finland's first industrial-scale wind turbine in 1999.
Putting that expertise into Arenso means both asset companies can buy the same services from one provider. It also means a future partner in Tahkoluoto Offshore can contract for Finnish offshore operating experience without having to own a share of the onshore fleet to get it. Enerdatics records Arenso alongside Suomen Hyötytuuli and Tahkoluoto Offshore in the ownership of several of the projects.
Enerdatics' data shows how offshore partnerships in Finland have been priced so far. Enerdatics records 30 wind transactions in Finland announced between January 2023 and June 2025. Six carry a disclosed value. Only one of those is described as offshore: Ingka Group paid $195.08 million in May 2023 for a 49 percent stake in OX2's Finnish offshore wind pipeline, recorded at 5,120 MW. Grossed up to 100 percent, that values the pipeline at about $398 million, or roughly $0.08 million per MW. Leap also records a November 2023 partnership between Lhyfe, Copenhagen Infrastructure Partners and Flexens to develop an offshore wind and hydrogen hub in Finland.
What does the demerger signal for Finnish offshore wind?
It signals that Finnish utilities appear to be preparing their offshore projects for outside partners rather than funding them alone. The OX2 and Ingka deal set a template: a developer keeps control and sells a large minority stake at an early stage. A separate Tahkoluoto Offshore company is the vehicle that makes the same kind of deal possible here.
It also shows the Finnish onshore market growing up around it. Onshore farms are now traded as finished assets, as in DWS's purchase of the 41.3 MW operational Maaselänkangas wind farm, and large pipelines change hands before permits, as when Metsähallitus sold an 810 MW Finland wind pipeline at permit-risk stage. Separating offshore from onshore lets Suomen Hyötytuuli's owners take part in both markets on different terms.
What the records do not yet show is who the partner will be. The company targets 1.9 TWh of annual production in the near term, more than double its output at the time of the demerger, and the 700 MW extension alone is expected to produce 2.6 TWh a year. The ownership question is now open in a way it was not before.
Frequently asked questions
What are the three companies created by the Suomen Hyötytuuli demerger? Suomen Hyötytuuli Oy owns the existing onshore farms and the current Tahkoluoto offshore farm, Tahkoluoto Offshore Oy owns the Tahkoluoto demonstration and extension project, and Arenso Oy provides wind energy life-cycle services to both.
Who owns Suomen Hyötytuuli? Eight Finnish energy companies: Helen (through Oy Mankala Ab), Alva-yhtiöt, Lahti Energia, Lappeenrannan Energia, Pori Energia, Tampereen Sähkölaitos, Turku Energia and Vantaan Energia. They own all three demerged companies and take the power from the assets.
How large is the Tahkoluoto Extension offshore wind farm? Enerdatics records the Tahkoluoto Extension at 700 MW with an investment of $2.57 billion, financial close expected in mid-2027 and operation expected in 2030.
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