The expansion work on Vaasan Voima’s thermal energy storage (TES) has progressed well this year at the Vaskiluoto power plant area. According to Vaasan Voima’s Managing Director Janne Österback, the expansion project, which has lasted about a year, has now advanced well past the halfway point in all construction phases.
“Significant progress has been made especially in the excavation of the technical space, where a depth of about 25 meters has already been reached. In other respects, the construction work is currently focused mainly on excavating the tunnel for the storage’s heat transfer network and sealing the storages. During the annual maintenance of the power plant, critical connections were made between the electric boiler’s electrical infrastructure and the district heating infrastructure of the plant’s process network,” Österback explains.
The ongoing expansion of the thermal storage is already the third since 2020, when Vaasan Voima commissioned the storage. In the project that started in autumn 2024, the storage temperature will be increased from the current 95 degrees Celsius to a temperature above the boiling point by utilising the static pressure created by the column of water.
The raise in temperature will increase the total capacity of the TES facility by more than 50% to 17 gigawatt-hours. The investment also includes a new 60 MW electric boiler suitable for steam production, an upgrade of the process network serving the system with higher temperatures, and a buffer tank.
“The ongoing expansion of the thermal storage is the most significant since the storage began operation in 2020. With the new, expanded storage facility, we will be able to deliver and store non-combustion-based energy even during the coldest winter months.”
The commissioning of the upgraded thermal storage is scheduled to begin in late 2025. Commercial production will start at the beginning of 2026.
For more information: Janne Österback, Managing Director of Vaasan Voima, tel. 010 5055 235
