Several investments over the years
The Suomenoja plant has been in production since 1977. Over the recent years, several investments were made in order to discontinue the use use coal and transform heating towards electricity-based heat production. At the moment, the plant consists of four CHP units, as well as a heat pump plant that re-uses heat from treated wastewater. The 60 MW heat pump plant includes three heat pumps that provide up to 25% of all the heat consumed in the district heating network area.
The Suomenoja site also hosts a 20,000 m3 heat accumulator that can store about 800 MWh of heat energy in water. In addition, a 100 MW electric boiler plant was commissioned on the site in 2023. Together, they can increase flexibility in production: the electric boilers can heat the district heating water during periods of cheaper power prices, and furthermore, this energy can be stored in the accumulator and released to the network when heat demand peaks.
In 2024, the last coal burning unit in Suomenoja was closed down permanently on 28.4.2024, over a year ahead of schedule. This historical decision was enabled by the advanced electricity-based roadmap and production.