[csomar]

The battery (am assuming it's just sand and metal) should be very cheap compared to Lithium especially in the places where you generated solar energy (they are hot and have a lot of sand).

The problem is: is it profitable to even store energy there? There is no mention beyond "In operation, the sand battery has demonstrated a round trip efficiency of 90 percent.". That doesn't mean much if you do not compare it to Lithium and you don't give me a breakdown of the costs.

The other thing: Size. Is that big thing enough to store energy for a city? a neighborhood? A building? A house?

If it's enough just for a house, then I have trouble seeing this scale.

[kragen]

1 MW is enough to heat somewhere between 100 and 2000 houses, depending on other factors like insulation, climate, and house size.

[Sharlin]

It's right in the title. 1 MW/100 MWh.

[rsynnott]

If your house is consuming 100MWh in heating on any reasonable timescale, you, ah, have problems :)

[yencabulator]

But at least the problems will be short lived! Should reach self-ignition pretty quickly with that, even in the middle of Finnish winter.