That's a really great application. I wonder if a thermal battery could be used for both heating and cooling.
this post was submitted on 19 Aug 2026
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It's easier to freeze water than to cool rock borehole
The problem with freezing water is the material expansion.
that's no problem at all, systems like that are in use
I bet it could, same principal and application. Take heat from homes during the day and apply at night. Problem only swaps from "do we have enough to make it through the night" to "do we have enough capacity to make it through the day"
Take heat from homes
That's the tricky part.
This sand battery works by offsetting the production of heat to be used in an already existing district heating system.
That system does not easily change into a district cooling system. It is simply not built to run in reverse. Every part of it from production through distribution, exchanging and in-house distribution are made with one purpose: To transfer heat in one direction.
It makes sense to use renewable energy to charge this battery, so they don't need as much fossil fuel or whatever they use normally.
But, if we were to make a district wide hvac-system the same way, it would probably be better and more efficient to simply use individual airconditioners using the renewable energy directly.
0c water kept cool by a big ice tank. Traditional radiators wouldn't work but there are options that do. High thermal mass of water too.
I personally think these types of non-conventional batteries are going to be the future of storing energy for use at offset peak usage times.
It would be great if every city could construct multi thousand megawatts of grid scale battery capacity but that probably isn't feasible with traditional chemistry batteries. But, in some areas the same effect could be accomplished with something like "potential energy batteries", for example, using massive solar arrays to pump water into an elevated reservoir during the day at peak solar generation, then releasing that water to drive turbines and generate on-demand electricity at other times.
It's feasible with the newer sodium ion batteries. They're already being installed for grid use. Similar to lithium batteries, but they're less volatile and can be charged much faster.
They're better suited for grid use than consumer use due to having less energy density than lithium.
we don't even have to build anything new, aside from installing heat pumps which we should be doing anyways for a multitude of reasons such as "i like not dying of heatstroke".