Clean energy transition advances in Hanasaari – main transformers now in place at Europe’s largest electric boiler plant

Europe’s largest electric boiler plant has reached a major milestone: the facility’s two main transformers have arrived at Helen’s Hanasaari site in Helsinki. The plant will cover the district heating needs of an area equivalent to two Lauttasaari neighborhoods, using carbon-neutral electricity. Elomatic and A-Insinöörit are delivering the project as Helen’s EPCM partners.

Europe’s largest electric boiler plant (200 MW), along with its thermal storage tanks, is currently under construction at the Hanasaari energy district in Helsinki. The project reached one of its most significant phases this week, when the two high-capacity main transformers, each weighing over 100 tons, arrived by special transport and were installed in the plant building.

The consortium of Elomatic and A-Insinöörit has overall responsibility for project management, engineering, procurement, site management, and supervision as Helen’s EPCM partners.

The plant consists of four 50 MW electric boilers and two thermal storage tanks. The boilers heat water for the district heating network during periods when electricity supply is sufficient and prices are favorable. Installation of all four boilers was completed in April, in the plant building that reached ridge height last winter.

“The main equipment is now on-site. The massive transformers have been moved into position, and we can focus on continuing the piping and electrical installations needed to connect them. After installation and inspection, we move into commissioning, which will include an intensive testing program,” says Pekko Pennanen, Project Manager for the EPCM project at A-Insinöörit.

“Large power transformers are extremely heavy, and their safe transport is critical – lead times for this type of transformer are very long. Once installed, the transformers go through several tests to verify they can be safely energized. The transformer steps voltage down from 110 kilovolts to 10 kilovolts, making it a high-voltage device,” says Karl-Gustav Pihl, Design Manager responsible for electrical engineering at Elomatic.

The plant adds flexibility to heat and electricity production

The plant includes two thermal storage tanks with a combined capacity of 1,000 MWh. These tanks hold district heating water and are still under construction. Heat can be stored in the thermal batteries and used later to heat Helsinki homes and buildings.

The combination of electrode boilers and thermal storage is designed to balance heat and electricity production and to manage price fluctuations. Construction began in summer 2025.

The shift to carbon-neutral, wind-powered energy has been visible at the Hanasaari site throughout the project: the coal stockpiles are gone, and Helsinki residents have had the opportunity to visit the area.

“Building a large-scale district heating plant powered by electricity brings together several engineering disciplines in a comprehensive and fascinating way. Careful coordination between them, and close collaboration throughout the project team, has been, and will continue to be, essential to the project’s success,” says Pennanen.

The Hanasaari electric boiler plant is on schedule and will be commissioned during the 2026-2027 heating season. The plant is part of Helen’s goal to phase out combustion-based energy production by 2040.

Further information:

Karoliina Joensuu, Industry Director, Elomatic
tel. +358 50 412 0546
karoliina.joensuu@elomatic.com

Anu Kuoppamäki, Industry Director, A-Insinöörit
tel. +358 50 341 1360
anu.kuoppamaki@ains.fi