Metsä Fibre, part of Metsä Group, and Rauman Energia are progressing with their joint project to utilise waste heat from the Rauma pulp mill in district heat production in Rauma. The new district heating station required for the project has arrived at the mill site, and preparations for commissioning the system are under way. The aim is to start heat production in December 2026.
In the project, waste heat generated in the processes at the Rauma pulp mill will be recovered and transferred to Rauma’s district heating network. Following the arrival of the new district heating station at the mill site, the next steps are to connect the station to the mill’s systems, carry out testing and commission the system.
Preparations for the project at Metsä Fibre’s Rauma pulp mill have been under way since 2025. The necessary connection points were built into the mill’s steam and condensate systems during the 2025 annual maintenance shutdown. Construction of the district heating pipelines at the mill site began in January 2026, and the pipeline installations were completed during the spring.
Experts from Metsä Fibre and Rauman Energia have been involved in the planning and implementation of the project. Particular attention has been paid to safety throughout the project, and the installation work has been carried out safely and systematically. Safe and efficient operation will continue to be a priority.
More efficient use of waste heat
The heat to be utilised in the district heating network originates from the Rauma mill’s recovery boiler, which is part of the pulp mill’s chemical recovery cycle. Black liquor is combusted in the recovery boiler, and the resulting heat is used to generate steam. The steam is primarily used to generate electricity in the turbine and generator and in the pulp mill’s processes.
The Rauma pulp mill generates more energy than is required for its own processes. Until now, some of the unutilised waste steam has had to be cooled in the condenser, with heat dissipated through cooling towers. The new district heating station will enable this waste heat to be utilised more efficiently and transferred to Rauma’s district heating network.
It is estimated that the heat utilised through the project could cover approximately 10–20% of Rauman Energia’s total heat demand.
“The project improves the energy efficiency of the Rauma pulp mill and enables us to utilise waste heat more efficiently than before. At the same time, we are reducing the amount of energy required to cool the heat and improving the mill’s overall efficiency. It is great that we can do this together with a local partner,” says Jaakko Rautala, Production Manager at Metsä Fibre’s Rauma pulp mill.
“This project is a good example of the benefits of a district heating system. The district heating network connects different heat sources while also serving as a distribution platform for thousands of our customers. Decentralised heat production increases both security of supply and cost efficiency. For us, this project is also an excellent addition to our production capacity, helping to secure heat production during disruptions and exceptional situations. Hopefully, it will mean that we need to start up our oil-fired backup and peak-load heating plants less frequently in the future,” says Jouni Kartano, Director, District Heating at Rauman Energia.
Testing of the system is scheduled to begin in early December. The aim is for the system utilising waste heat to be in production use by the end of December.
See how waste heat from the Rauma pulp mill is utilised in this process illustration: https://databank.metsagroup.com/l/T9_b2-ft6SSR