Steady Energy: Bringing small modular reactor technology to district heating

The problem

Replacing fossil fuels in district heating requires sources of dependable and low-emission heat. Nuclear reactors can fulfil this role, but conventional reactor technology is designed primarily to generate electricity. Finnish company Steady Energy set out to build an SMR specifically for district heating.

How we got involved

Fortum initially provided process-design and simulation expertise to support the development of Steady Energy’s LDR-50 small nuclear reactor. The collaboration deepened in January 2026, when Fortum signed a framework agreement to support the development of Steady Energy’s operation and maintenance concept and invested EUR 2.1 million in the company through Fortum Innovation & Venturing. The investment opportunity came through I&V’s partnership with Valo Ventures, who is also an investor in Steady Energy.

What we did together

Fortum is supporting Steady Energy in developing the operation and maintenance model for the LDR-50, as well as the functions needed to operate future plants.

Under the framework agreement, Fortum’s role could later extend to providing operation and maintenance services for Steady Energy plants in Finland and Sweden.

Where it is now

Construction of a full-size, non-nuclear pilot plant began in Helsinki during 2026. The facility uses electric heating to simulate the LDR-50 and demonstrate its safety features. It will also help to prepare the supply chain and operating model.

Commercial projects are already progressing. Steady Energy has submitted a proposal for ten LDR-50 units to energy provider Helen, while an environmental impact assessment is under way for a potential two-unit project with Kuopion Energia. 

Steady Energy has also secured around EUR 70 million in new investment commitments. Following a share exchange with 3North Partners, the company began trading on Nasdaq Helsinki’s First North market in October 2026.