At the forefront of the EU’s transition, Finland accelerates its clean energy agenda by deploying high-efficiency electrode boilers across critical heat networks
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 support decarbonization goals, reduce emissions from heating networks, and help stabilize 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.
In the EU’s broader decarbonization effort, high-voltage electrode boilers play a critical role in applications requiring rapid load absorption and grid stabilization.
Finland, in particular, has set one of the most advanced climate policies in the region, committing to carbon neutrality by 2035. Part of the European Union since 1995, the country has established interim emission reduction targets of 60% by 2030, 80% by 2040, and 90–95% by 2050, all relative to 1990 levels.
Like other EU members, Finland is striving to take advantage of financial and policy incentives such as the Recovery and Resilience Facility (RRF), a major EU funding program launched after the pandemic to promote electrification, renewable energy deployment, and resilience. The program is allocating approximately €672.5 billion to EU member states, distributed through a combination of grants and loans.
Like all EU member states, Finland must fully implement all RRF-funded initiatives by the program deadline of August 2026.
To meet its ambitious goals on schedule, Finland is directing a significant portion of the approximately €500 million it has already received toward modernizing its energy infrastructure, with a particular emphasis on the deployment of high-efficiency electric boilers.
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 percent output, and feature flexible configurations—including jet-type and immersed electrode designs—suitable for both new installations and retrofit projects in industrial and district heating applications.
«Electrode boilers are being installed across district heating networks to help decarbonize thermal energy production, offset fossil-fueled 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,» says Juha Mäntynen, Vice President of CT Industrial Oy (CTI), a Finland-based CleanTech provider specializing in turnkey, zero-emission, high-efficiency energy systems—including high-voltage electrode boilers—for industrial and district heating applications across 19 European countries.
Grid Stabilization
In the EU’s broader decarbonization effort, high-voltage electrode boilers play a critical role in applications requiring rapid load absorption and grid stabilization, according to Mäntynen.
Electrode boilers are instrumental in generating revenue by absorbing excess power, enabling rapid, demand-responsive operation that aligns with market conditions.
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.
This is a key consideration for Finland, given its substantial investments in renewable energy over the past 15 years. By the end of 2023, Finland had approximately 1,600 operational wind turbines with a combined capacity of nearly 7,000 megawatts, including over 1,200 MW added that year alone. Wind has become Finland’s second-largest electricity source, generating roughly 19.8 terawatt-hours in 2024—enough to supply 24–25% of national electricity demand. The country also makes significant investments in heat recovery, heat pumps (air to heat), offshore wind, solar, and nuclear energy.
The Reserve Market and Negative Prices
As renewable energy production grows across Europe, instances of negative electricity pricing are occurring more frequently. This creates a financial opportunity for energy consumers who participate in the reserve market, allowing them to generate revenue by absorbing excess power. Electrode boilers are instrumental in leveraging this trend, enabling rapid, demand-responsive operation that aligns with market conditions.
According to Mäntynen, when wind production exceeds demand, surplus electricity causes prices to drop sharply, sometimes becoming negative. He explains that a negative electricity price means that electricity producers are paying people to take electricity off the grid, instead of customers paying for electricity.
Companies that participate in reserve markets can earn considerable revenue by consuming excess electricity to balance the grid.
Many cities are phasing out biomass-fired plants in favor of modern technologies such as electrode boilers.
The reserve electricity market—also known as the ancillary services or balancing market—is essential for maintaining grid stability by compensating producers and consumers who can quickly adjust power generation or consumption. This market ensures reliable system frequency and reduces blackout risks by responding to sudden shifts in supply and demand. Technologies like electrode boilers are particularly valuable in this context, as they can rapidly absorb excess electricity or shut off on demand, making them effective tools for balancing the grid in real time.
«Under favorable conditions, an electric boiler can pay for itself within a year or less. For example, last year, the average price paid for reserve market electricity consumption was three thousand (3000) euros per megawatt-hour. A 50-megawatt boiler operating for one hour could earn approximately 150,000 euros,» says Mäntynen.
Thermal Power and District Heating
Thermal power and district heating are also critical to Europe’s energy infrastructure, supplying consistent heat to millions of homes and businesses while supporting grid reliability. These systems play a key role in energy security, especially in colder regions and during peak demand periods.
Finland operates one of the most advanced district heating networks globally, spanning over 16,000 kilometres of underground insulated piping and serving approximately half the population, particularly in urban areas. The system distributes hot water, typically heated between 65°C and 115°C, depending on outdoor temperatures, and returns it at 40°C to 60°C, with minimal heat loss of just 8–9%.
While the network historically relied on coal, peat and wood chips, it is now undergoing a major transition toward renewable and low-carbon energy sources. Many cities are phasing out biomass-fired plants in favor of modern technologies such as electrode boilers.
Relatively cheap electricity prices and taxation benefits have made Finland an attractive location for large data centers operated by companies like Google and Microsoft. Data centers produce a large amount of waste heat from cooling processors, and this waste energy has been used to heat cities in Finland.
«Heat pumps generate base energy from data centers, while electrode boilers increase the district heating water temperature to reach the required temperature level for city needs,» says Mäntynen.
To accelerate deployment, CTI has teamed up with Acme Engineering to expand electrode boiler implementation across Finland and other European markets.
Acme’s products are distinguished by their wide range of designs and technical flexibility. The portfolio includes the jet boiler, capable of handling higher pressures with zero to 100 percent modulating capacity, and the immersed electrode boiler, which can be configured for either hot water or steam applications. Additionally, the OEM offers a horizontal hot water boiler design that is particularly well-suited for retrofit projects. A variety of voltage options are available to meet different regional requirements.
Electrode boilers can adjust their electricity consumption almost instantly, allowing them to absorb excess power during periods of oversupply.
Today, CTI partners with Acme to provide high-voltage electrode boilers to the European market under the ACME-CTI brand. CTI manufactures and delivers electric boilers for steam and hot water production, serving both the energy and process industries. These systems are based on proven electrode boiler technology developed by ACME and are CE marked in compliance with standards established by the European classification society. Boiler design and production meet the requirements of EN 13445 and EN 12593. CTI oversees the complete delivery process of the electric boiler system, from initial planning through installation, with ongoing support also available.
Together, CTI and Acme form a highly nimble and technically capable partnership, offering customized solutions, rapid modifications to existing equipment, and a high degree of responsiveness to customer requirements.
«Acme is a small, agile company, allowing it to quote, make decisions, and adapt to customer needs much faster than larger, more bureaucratic boiler manufacturers,» says Mäntynen.
As demand for clean energy solutions ramps up, a significant milestone was achieved when CTI successfully lifted the first European ACME-CTI 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 demineralized water system, feed water system, and blowdown system, with automation integrated into the customer’s existing boiler setup, all turnkey delivered.
Even more recently, CTI 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 manufactured by CTI 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 fertilizers).
Modern high-output electrode boilers like those from Acme Engineering deliver zero emissions at the point of use, offer full modulation from zero to 100 percent output, and feature flexible configurations.
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, CTI has nine turnkey projects underway.
A notable recent development includes the signing of an additional order for two 50-megawatt 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, CTI created a solution that met both needs simultaneously.
The European market for decarbonization technologies remains resilient, driven by sustained municipal investment in clean energy infrastructure aligned with long-term carbon reduction mandates. As demand continues to rise, 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.
