HeatVentors' HeatTank uses phase-changing materials to concentrate and store heat or cold; the reverse occurs for discharging phase

https://interestingengineering.com/a-new-smart-tank-is-90-smaller-than-water-based-energy-storage-solutions

"patented technology allows it to produce storage devices that are 90 percent smaller than water-based storage technologies and that it can store more energy while producing fewer CO2 emissions. The system can be attached to smart homes, data centers, and could potentially also be used for larger grid-based energy storage"

Related: Cryogenic Energy Storage: A Technological Breakthrough for Clean Energy

https://www.energyportal.eu/news/cryogenic-energy-storage-a-technological-breakthrough-for-clean-energy/41626/