https://www.energy-storage.news/worlds-first-large-scale-sand-battery-goes-online-in-finland/
“The ‘sand battery’ explained: Insulate a lot of sand and heat it with an electrical element (300-500°C). When you need the energy back, pump air into it and you get hot air to power generators and heat buildings.
The first commercial sand-based thermal energy storage system in the world has started operating in Finland, developed by Polar Night Energy.
Polar Night Energy’s system, based on its patented technology, has gone online on the site of a power plant operated by utility Vatajankoski.
The 4×7 metre steel container contains hundreds of tonnes of sand which can be heated to a temperature of 500-600 degrees Celsius. The sand is heated with renewable electricity and stored for use in the local district heating system.”
It is the second major thermal storage facility based on a unique (if not novel) technological solution that has progressed this week. Swedish public utility Vattenfall is about to start filling a 200MW-rated thermal energy storage facility, effectively a giant water tank, in Berlin.
https://www.energy-storage.news/vattenfall-starts-filling-up-200mw-thermal-storage-tower-in-berlin/