Can a sand battery provide heat?

I saw a Finnish company, Polar Night, has made and demonstrated a sand battery that can reach 600⁰C and can provide heat for months using geothermal techniques. Has anyone come across a domestic / DIY version of this? I saw a guy on YT make a proof of concept with a kettle coil, but I'm curious if anyone has dived into this?

What is a sand battery?

The inventor also calls it a "heat storage device for long-term heat storage of solar energy and other types of energy". For those who prefer straightforward guides on how to build a sand battery, take a look at this video showing the "rocket stove" sand battery:

How efficient is a sand battery?

Not heard of sand before. Even if the thermal mass storage is 100% efficient, a heat-pump beats it. Most good mini-splits do a COP of 5. So for every 25 watts of heat you pump in them, you get 125 watts of heat out. 500% efficient. I’m am building a rather large sand battery in which I plan to build a house over.

How efficient is a mini split sand battery?

Most good mini-splits do a COP of 5. So for every 25 watts of heat you pump in them, you get 125 watts of heat out. 500% efficient. I’m am building a rather large sand battery in which I plan to build a house over. It consists of two large room size insulated boxes 10 feet deep.

Should I build my own sand battery?

Stay safe, and good luck if you decide to construct your own sand battery! A substantial piece of land that you are not too fond of. The excavation work will disturb your lot even if the excavator operator is careful.

How do you heat sand with a solar batch collector?

A series of 4 inch perforated drain pipe will run to vents in the floor. Atop the perforated pipe will be 12 inches of 2 inch rock and a layer of metal several feet of sand which is topped with a layer of 2 inch rock. The idea is to use the solar batch collectors to heat the sand with hot air during the late summer into the fall months.