A seasonal thermal energy storage will be built in Vantaa, which is Finland’s fourth largest city neighboring the capital of Helsinki.

The total thermal capacity of the fully charged seasonal thermal energy storage is 90 gigawatt-hours. This capacity could heat a medium-sized Finnish city for as long as a year. Broken down into smaller energy units, this amount of energy is equivalent to, for example, 1.3 million electric car batteries.

The project cost is estimated to be around 200 million euros, and it has already been awarded a 19-million-euro investment grant from Finland’s Ministry of Economic Affairs and Employment. Construction of the storage facility’s entrance is expected to start in summer 2024. The seasonal thermal energy storage facility could be operational in 2028.