Cross posted from: https://feddit.de/post/11209517
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.
It might interest people that the soon-to-be previous biggest thermal energy store is also located in Finland, under the island of Mustikkamaa in the capital city of Helsinki. The city heating company Helsingin Energia “charges” the store by pumping heat out of sewage in summer. I think it was about 10 gigawatt-hours and it’s not pressurized, so water can only reach 90 C over there.
(A side note: if you allow water at 140 C to boil in a controlled manner, you get steam, which can also produce electrical power, although probably in a suboptimal manner.)
Finnish bedrock seems more suitable than average rock for such ventures (which I would call “artificial geothermal energy”) - granite is a poor thermal conductor and a reliable rock for making caverns.
I hope it goes well. :)