Joel Aartolahti

Associate, Member of the Finnish Bar

Services

  1. Environment, Energy & Green Transition

Contact details

I advise our clients in matters related to the environment, infrastructure and natural resources.

Before joining Castrén & Snellman I worked as a lawyer at another law firm and concentrated on real estate and construction related matters. Before my graduation I worked as a trainee in the real estate and environment team of another major law firm.

I graduated from the University of Helsinki in 2021. In addition, I studied energy and environmental law at the University of Aberdeen in Scotland for one semester.

Latest references

Downing – Acquisition of the entire share capital of Tornionlaakson Voima
We advised UK-based investment company Downing in its acquisition of the entire share capital of Tornionlaakson Voima Oy. Tornionlaakson Voima owns three hydropower plants in the Tengeliönjoki river system – the Portimokoski power plants in Ylitornio, the Jolmankoski power plants in Raanujärvi and the Kaaranneskoski power plants in Sirkkakoski. The power plants produce a total of approx. 45 gigawatt-hours of electricity per year. Tornionlaakson Voima’s daily operations will continue normally, and the transaction will not affect customers. The consummation of the transaction is subject to the approval of the Ministry of Economic Affairs and Employment. Downing has over 35 years’ experience in providing a wide range of investment solutions to the needs of institutional investors, advisers and retail investors. The company manages over £2 billion in assets in both the private and public markets and its current hydro power portfolio includes approx. 50 hydro power plants in the Nordics. 
Case published 27.3.2026
Merger of Oomi and Lumme Energia
We are acting as the joint legal advisor to Oomi Oy and Lumme Energia Oy in a transaction whereby Lumme Energia will merge with Oomi. As from the completion of the merger, the combined entity will be the largest electricity retail and service company in the Finnish market. In 2024, Oomi reported a turnover of EUR 373.9 million and had approximately 110 employees. Lumme Energia’s turnover for the same year was approximately EUR 314.6 million and it had approximately 50 employees. The transaction is primarily driven by the recent developments in the electricity market and the strategic goal to develop competitive products and services. Another key objective is to further enhance the customer experience, which is a shared value between the two companies. As a result of the merger, Lumme Energia’s customers will transfer to Oomi, and Lumme Energia will become one of Oomi’s shareholders. The completion of the transaction is subject to an approval by the Finnish Competition and Consumer Authority.
Case published 29.8.2025
Fortum – Acquisition of a project development portfolio for renewable power from Enersense
We are acting as a counsel to Fortum in a transaction in which Fortum is strengthening its renewable power project pipeline through the acquisition of a project development portfolio from Enersense. The debt-and-cash free purchase price is approximately EUR 9 million, with the potential for project-specific earn-outs subject to projects successfully reaching a final investment decision in the future. The transaction is subject to customary closing conditions and is expected to be completed during the first quarter of 2025. Fortum is a leading Nordic energy company with the purpose to power a world where people, businesses and nature thrive together. Fortum’s core operations comprise of efficient, CO2-free power generation as well as reliable supply of electricity and district heat to private and business customers. The company is listed on Nasdaq Helsinki. One of Fortum’s strategic targets is to develop at least 800 MW of ready-to-build onshore wind and solar projects by the end of 2026.
Case published 19.12.2024
Hanza AB – Acquisition of Leden Group
We acted as Finnish advisor to Hanza AB relating to its acquisition of all the shares in Leden Group Oy. Hanza AB is a Swedish mechanical engineering and electronics contract manufacturing company listed on the Stockholm Stock Exchange. Founded in 2008, the company has six manufacturing clusters in Sweden, Finland, Germany, Baltics, Central Europe and China and an annual turnover of approximately SEK 4.6 billion. Leden Group is a leading Finnish contract manufacturer specialising in sheet metal, machining and complex assembly. Leden Group has four production sites in Finland and one in Estonia and an annual turnover of approximately SEK 1.1 billion. 
Case published 13.12.2024
Fortum – Sale of recycling and waste business
We acted as the lead counsel to Fortum in a cross-border transaction in which Fortum sold its recycling and waste business. The business was sold to thematic impact investing firm Summa Equity through its portfolio company NG Group. The debt-free purchase price is approximately EUR 800 million.  Fortum’s recycling and waste business to be sold comprises municipal and industrial waste management and end-to-end plastics, metals, ash, slag and hazardous waste treatment and recycling services. These businesses are located in Finland, Sweden, Denmark and Norway and currently employ approximately 900 employees.
Case published 18.7.2024
Delta Capacity – Project financing of two battery energy storage systems (BESS)
We advised Delta Capacity AG in a project financing of two battery energy storage systems (BESS). The financed projects are among the largest BESS developments in Finland to enter construction with 250 MW / 600 MWh combined capacity. The financing was provided by Société Générale with support from Finnvera. Construction of both projects, located in Lapinlahti and Teuva, has already begun and the commercial operations are targeted to commence in late 2027 with partial tolling agreements already in place for both assets. The project in Lapinlahti is executed in partnership with Covenergo, while the project in Teuva is executed in partnership with Strioga Family Foundation. Delta Capacity is a Swiss developer of utility-scale battery storage systems. The projects strengthen Delta Capacity’s growing Nordic portfolio and support the flexibility of Finland’s electricity system by adding energy storage capacity, enabling production optimization as well as participation in electricity markets and reserve services.
Case published 28.10.2026
Martela Corporation – Directed share issue and combination of share series
We acted as legal adviser to Martela Corporation in its directed share issue, through which Martela raised gross proceeds of approximately EUR 7.2 million to strengthen the company’s financial position and liquidity and to create headroom for continuing the necessary development and efficiency measures. In connection with the directed share issue, Martela’s unlisted series K shares, which carried greater voting rights, were combined with its listed series A shares. Following the combination, the company has only one share series, which is traded on the regulated market maintained by Nasdaq Helsinki Ltd, with each share carrying one vote and otherwise identical rights. Martela is a Nordic leader specialising in user-centric working and learning environments. With over 80 years of experience, Martela creates the best places to work and offers its customers the Martela Lifecycle solutions which combine furniture and related services into a seamless whole.
Case published 27.10.2026
Banyan Software – Acquisition of Carus Ferry
We acted as legal adviser to Banyan Software on its acquisition of Carus Ferry, a Finland-based provider of reservation, check-in and port operations software for ferry and passenger shipping operators. The acquisition further strengthens Banyan Software’s presence in the Nordic region while providing Carus with a long-term partner to support its continued growth and development. Carus was founded in 1998 and is headquartered in Mariehamn on the Åland Islands, Finland. The company develops mission-critical software for ferry, cruise and passenger shipping operators, covering the full passenger journey from booking and ticketing to capacity management, check-in and boarding. Carus also provides port automation, onboard sales systems and business information tools. The company serves approximately 30 operators across four continents and is the largest vendor by customer count in ferry reservation and departure control. Banyan Software is an acquirer and long-term operator of mission-critical software businesses serving specialised industries. Founded in 2016, Banyan follows a buy-and-hold-for-life approach and supports the long-term growth and development of its portfolio companies. Banyan operates more than 130 portfolio companies across North and South America, the United Kingdom, Europe and APAC. Following the acquisition of Carus, Banyan operates three businesses in the Nordic region.
Case published 20.10.2026

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