Feolite, one of many materials used for heat storage, being a solid, does not have any volumetric or pressure containment issues, but correspondingly does require the use of a transfer medium to then get the stored heat to the desired location.
Heating systems with a storage component now widely use feolite as the storage core.
Application
Blocks of feolite enclosing sheathed electric heating elements to form a heat storage core, surrounded by thermal insulation, are used in storage heaters and storage radiators. Because feolite blocks will conduct electricity, electric heating elements must be electrically insulated when used with feolite storage.
The typical heat exchange medium for feolite storage is air.
Feolite has been considered for use as a component for braking systems in railway rolling stock.