So the sand just gives out heats for longer time ??? Please explain how this works iam very eager to learn

Trying to figure out a way to make free significant electricity and storage with the sand battery. Was thinking about heating water with hot water expansion and current to power a hydraulic turbine. But then ran into peltier devices and Stirling engines. Was also thinking about using mirrors for solar heating and semi concentrating the rays through clear plastic sheeting as a larger solar oven system to heat the sand battery and keep it hot while the heat exchanger creates electricity (which would work great on sunny winter days and the heat would be there continue to exchange during cloudy day and at night). Currently I’m trying to find out what rate of heat loss there is with smaller sand batteries like a 55 gallon drum (possibly even insulated part of the drum with the heated part still exposed and the heat exchanger engine unit exposed) or possibly two or three drums welding together or something a bit bigger that has to be manufactured but still small enough to fit into a backyard and not the size of a silo. Would make an excellent alternative to creating electricity in a backyard that doesn’t require solar panels attached to roofs or a tower for a windmill and also be another backup for electric power supply to homes, storage, and the grid. But I could be wrong and you may need something the size of a silo to hold all that heat unless another material could be used for a heat battery.

Why not store the sand below ground?

What about in places where sun isn’t prevalent a lot ?