13.10.2025
Kainuun Voima tested Joensuu Biocoal’s biocoal as a supporting fuel under summer conditions during minimum load operation. The goal of Kainuun Voima was to find an emission-free solution capable of maintaining the bed temperature of a circulating fluidised bed multi-fuel boiler with the the lowest possible amount of fuel mixture.
Over the past year, Joensuu Biocoal has delivered several test batches to its customers. Joensuu Biocoal is biocoal production company. Taaleri has arranged the financing of the company and supported its early-stage development. One of these tests was conducted by Kainuun Voima, which tested the use of biocoal at its CHP (Combined Heat and Power) plant in Kajaani, Finland. The plant produces both district heating and electricity.
Testing under summer conditions
According to Kimmo Keinänen, CEO of Kainuun Voima, the biocoal tests were deliberately conducted during summer conditions.
The plant’s multi-fuel circulating fluidised bed (CFB) boiler uses a mixture of different fuels for energy production. These fuels vary in their properties and, especially during the summer, maintaining the boiler’s bed temperature requires a fuel that is dry and consistent in quality.
In the winter, when demand is high, the boiler can operate at full capacity using its main fuel, wood chips. In the summer, however, variations in moisture and quality of the wood chips present challenges.
Kainuun Voima tested biocoal as a supporting fuel. According to Keinänen, biocoal proved to be a renewable and high-energy alternative to fossil fuels. It improved the energy content of the fuel mixture and added value by addressing challenges related to fuel quality variations, making the boiler easier to control, even at lower load levels.
Antti Wilkman, CEO of Joensuu Biocoal, notes that challenges related to fuel moisture and quality variations can arise regardless of the season.
“Biocoal can be used at any time of year when there is a need to improve the stability of the fuel mixture. It also provides an extra boost during peak winter demand, as its energy value exceeds that of fuels such as wood chips and pellets,” says Wilkman.
"Biocoal can add real value to our fuel mix. It is simple to use, as it can be handled at the site regardless of weather."
Kimmo Keinänen
CEO, Kainuun Voima
A drop-in solution for existing systems
Joensuu Biocoal supplied the Kajaani plant with agglomerated, i.e. briquetted, biocoal. The use of biocoal was simple and straightforward: No changes to plant technology or production processes were required and biocoal functioned as a drop-in solution. Biocoal was introduced to the energy production system along existing conveying lines.
"After some hiccups at the start, Joensuu Biocoal's briquettes stayed together well with the conveyors and remained in larger pieces even after the disc screen, ensuring sufficient residence time in the CFB boiler," says Keinänen.
“Biocoal can be used at any time of year when there is a need to improve the stability of the fuel mixture."
Antti Wilkman
CEO, Joensuu Biocoal
Coal-like performance without the fossil CO₂
For a long time, Kainuun Voima has been committed to reducing CO₂ emissions. The company took a forward-looking approach in testing biocoal, which shares the properties of coal while being a renewable alternative.
“Biocoal can add real value to our fuel mix. It is simple to use, as it can be handled at the site regardless of weather,” notes Kimmo Keinänen from Kainuun Voima.
“We are pleased with the testing setup, the solution-oriented approach and the implementation carried out together with Joensuu Biocoal,” he adds.
Antti Wilkman from Joensuu Biocoal reports that the biocoal briquette performed as intended across the supply chain and production process. He adds that the collaboration with Kainuun Voima has been both productive and valuable.
“Kainuun Voima has an innovative and open-minded approach to testing new products. It is fantastic to collaborate with a company that has a genuine interest in advancing the green transition in the energy sector,” says Wilkman.