The new biohybrid plant of Haapajärven Lämpö, the heating company of the municipality of Haapajärvi, was commissioned in late 2020. The town's spectacular flaming orange landmark boosts the area's circular economy and produces the least expensive district heat in Finland

The boiler island of the new heating plant in Haapajärvi was delivered by KPA Unicon. This was a partial delivery, as Haapajärven Lämpö procured the plant building and civil works as well as other peripheral equipment related to the plant, such as fuel reception and flue gas condensing equipment, as separate deliveries.

KPA Unicon’s delivery included a boiler with auxiliary equipment, installation, and commissioning. The boiler utilizes Unicon Renefluid fluidized bed technology. The boiler has a capacity of 20 megawatts (MW). In addition, the plant is operated and monitored by KPA Unicon’s digital PlantSys system. The control of all three heating plants of Haapajärven Lämpö is now centralized in the control room of the new biohybrid plant.

“The delivery was quite compact and suitable for us. The customer took on a big role, as they have the courage and professionalism as well as the experience they have gained over the years. This was the right price-quality solution for them,” says Esa Kukkonen, Sales Manager at KPA Unicon.

The new biohybrid plant will replace the old heating plant, which is more than 30 years old. The old plants will remain as backup and peak plants. The previous plant was also supplied by KPA Unicon.

“We know KPA Unicon and they know us. The cooperation works,” says Janne Alpua, CEO of Haapajärven Lämpö.

Best possible technology

The plant supplier was selected through a public tender. According to Alpua, the tender emphasized, among other things, fuel-related criteria. 80–85 percent of the plant’s energy sources come directly from the sawmill company Hasa Oy’s Haapajärvi sawmill, located on a neighboring plot.

By-products from sawmill production are used as fuel, mainly conifer bark, but also sawdust and woodchips. The moisture content of fresh sawn fuel poses its own challenges to burning.

Boilers using sawmill by-products as fuel are typically equipped with a rotating grate that is designed specifically for wet fuels. In Haapajärvi, however, a fluidized bed solution was selected.

“In Haapajärvi, heat is supplied in two directions: to the sawmill and to the town’s built-up area. When there is a large sawmill as a consumer, the load variation is very dynamic. Fluidized bed technology can respond to load variation better than grate technology,” says Kukkonen.

In Haapajärvi, the average fuel moisture content is 55–60 percent. Therefore, an air preheater was added to the boiler.

“The combustion air is preheated with flue gases before it is supplied to the boiler, which has an effect on the combustion process, especially when using wet fuel. In other respects, the boiler process is our typical delivery solution.”

The fuel is transported to the plant’s silo by truck. The silo has four blocks and when the plant is running at full capacity, the full silo can fuel the plant for one day.

“We also surveyed a conveyor directly from the sawmill, but it was too expensive an investment. The work continues in the same way as before, but now the plant is located closer to the sawmill,” says Alpua.

In addition to the sawmill, the plant also receives fuel through local wood chip suppliers and the Forest Management Association.

Provisions made to minimize emissions

The flue gases from the plant are led to the flue gas scrubber via electronic pre-filtration. With the flue gas scrubber, the flue gases formed during combustion are washed and the heat is recovered.

“Properly dimensioned pre-filtration and a flue gas scrubber meet the stricter standards for particulate emissions. At the same time, the flue gas temperature was significantly reduced: the temperature of the flue gas rising from the old plant’s chimney was 170 degrees, while now it is water vapor at 60 degrees,” says Alpua.

With the standards, Alpua refers to the Medium Combustion Plant (MCP) Directive, which will come into force in 2025. The directive sets new limit values ​​for sulfur dioxide, nitrogen oxide, and particulate emissions from 1 to 50-megawatt combustion plants.

“We made reservations for urea and ammonia inputs in the boiler. The actual inputs were not implemented during this project, because the fuel used in the plant meets the current limit values,” says Kukkonen.

“Making these provisions had a slight effect on the height of the furnace so that urea and ammonia inputs could be directed to different stages of combustion, if necessary,” he continues.

Without the new directive, the new heating plant in Haapajärvi would still be under construction. Now the plant has been up and running for almost two years already.

“According to the original plan, we would have a construction site going now. But with respect to the directive, it made more sense to tighten the timetable,” says Alpua.

The  bright spot of the town draws praise

The new plant is more energy efficient than the old plant, and maintenance costs have also dropped considerably. According to Alpua, maintenance is one of the major reasons why fluidized bed technology is relied on in Haapajärvi.

“The total maintenance costs of the new plant are more than 60 percent lower than the old plant. We have done the necessary maintenance by ourselves for ages and will continue to do so. Over the years, we will know more about the condition of the boiler itself. The fluidized bed boiler is easy to maintain.”

The project in Haapajärvi proceeded on schedule with almost no delays. The location was exceptional as the boiler was manufactured at KPA Unicon’s factories in Lapua and Kiuruvesi, within a radius of less than 200 kilometers from Haapajärvi. Kukkonen is satisfied with the result.

“The project schedule needs to be considered from two directions; it must not be too long but not too short either. Given the size of the project, the schedule was adequate. The location of the factories was a logistical advantage for the project.”

The new facility has received a lot of positive feedback from residents of Haapajärvi. The credit goes to Alpua for challenging the color choices of the architect who designed the facility.

“The architect had drawn it in gray, but I asked if we could use some other color. The facade then turned orange. We have received a lot of positive feedback saying that it does not look like a heating plant.”

For more information, please contact

KPA Unicon
Esa Kukkonen,, tel:+358500949678

Haapajärven Lämpö
Janne Alpua,, tel:+358444456100