Across Europe, high-voltage electrode boilers are quietly becoming a key part of the continent’s clean energy transition. In countries like Finland, these systems are being deployed to reduce emissions from heating networks and help stabilise power grids increasingly powered by variable renewable sources. As the EU advances its Green Deal and REPowerEU initiatives, technologies like high-voltage electrode boilers provide a practical way to convert surplus renewable electricity into useful heat while supporting the shift away from fossil fuels.

Modern high-output electrode boilers are CE-marked systems designed to generate steam or hot water using high-voltage electricity, with output capacities reaching up to 60 MW and steam production pressures as high as 32 barg. These systems deliver zero emissions at the point of use, offer full modulation from zero to 100% output, and feature flexible configurations – including jet-type and immersed electrode designs.

Immersed electrode boilers generate steam or hot water by conducting electric current through water. This technology is used with rapid-response district heating and grid-balancing. Jet-type boilers utilise high-velocity water jets to create turbulence and heat transfer and are useful when heating demands precise temperature control. Both solutions are suitable for new installations as well as retrofit projects in industrial and district heating applications.

Today, electrode boilers are being installed across district heating networks to help decarbonise thermal energy production, offset fossil-fuelled heat sources, and absorb excess electricity during periods of high renewable output. Their integration not only supports emissions reduction but also strengthens grid stability, making them a strategic investment in Finland’s broader path to carbon neutrality.

Electrode boilers are particularly important for maintaining grid balance as renewable energy production expands. Because wind and solar generation can fluctuate rapidly, the grid requires technologies that can respond just as quickly. Electrode boilers meet this need by adjusting their electricity consumption almost instantly, allowing them to absorb excess power during periods of oversupply. This makes it easier to integrate variable renewable sources without overloading the grid or wasting clean energy.

Electrode boilers are being installed across district heating networks to help decarbonise thermal energy production, offset fossil-fuelled heat sources, and absorb excess electricity during periods of high renewable output.

Implementation in Finland
To accelerate deployment, a Finland-based cleantech provider, CT Industrial Oy (CTI), teamed up with Acme Engineering, a manufacturer of environmental controls and systems, to expand electrode boiler implementation across Finland and other European markets.

A significant milestone was achieved when the Finnish cleantech provider successfully lifted the first European electrode boiler in September 2024. In June 2025, operating in Jepua, the 10 MW jet-type electrode boiler will soon generate 28 barg of steam for heating applications in industrial processes. The delivery scope also includes the demineralised water system, feed water system and blowdown system, with automation integrated into the customer’s existing boiler setup, all turnkey delivered.

Even more recently, the company installed a 15 MW electric boiler and feed water tank in the industrial area in Honkajoki. A new 15 MW electric boiler was also installed in connection with the Vatajankoski biomass boiler plant, which will increase the production of inexpensive and non-combustible steam.

The high-voltage electrode boiler will produce steam for use by Vatajankoski Oy. In the future, it will also be possible to store energy produced by an electric boiler in a heat accumulator, which will later be installed next to the plant. Heat from the accumulator will also be supplied to Honkajoki Oy (producer of high-quality renewable raw materials for animal nutrition, biofuels and fertilisers).

Currently, CTI is heavily engaged in the process industry sector, which is expected to be a major area of future growth for electrode boiler applications. At present, the company has nine turnkey projects underway.

A notable recent development includes the signing of an additional order for two 50 MW boilers. These boilers are intended for a project in the city of Kajaani, located in central Finland. Originally, the plan was to supply heat solely for the city’s district heating network. However, a new customer requirement emerged for a different temperature level than the city network typically demands.

CTI responded with an innovative proposal: using a single set of boilers to deliver two different thermal outputs without doubling the boiler capacity. By modifying the design to produce hotter water and then distributing it separately at two different temperature levels, the company created a solution that met both needs simultaneously.

The European market for decarbonisation technologies remains resilient, driven by sustained municipal investment in clean energy infrastructure. As demand rises, high-voltage electrode boilers are poised to play a pivotal role by converting surplus renewable electricity into heat, supporting grid stability and emissions reduction efforts, and creating energy ecosystems that are agile during fuel price fluctuations.

The views and opinions expressed in this article are strictly those of the author only and are not necessarily given or endorsed by or on behalf of the Energy Institute.

• Further reading: ‘How solar thermal storage can decarbonise industrial heat’. While the growth of solar power for electricity generation has been spectacular, the use of solar-generated power to produce and store heat for industrial users is at a much earlier stage. But the technology and potential is there, writes James Macnaghten, CEO of the UK-based energy storage supplier Caldera.
• Find out how thermal energy storage (TES) can play a key role in decarbonising hard-to-abate industry sectors – those that, typically, depend upon high temperature heat.