zlacker

I would guess that is intended for a daily cycle, perhaps using air source heat pumps at times of day when the air temperatures are higher and electricity prices are lower, then using it as required.

As it works on phase change (e.g. think of melting ice) heat is added (or removed) without changing the temperature of the store (which, I guess, might be hotter or colder than where the heat is extracted or used).

>>mike-t+(OP)
But how hot does the heat source have to be?

Depending on the needs, resistive heating can get hundreds of degrees hot, but the best heat pumps that I know of can only raise the temperature about 60 or 70° f.

>>gwbas1+0N
That's the whole point of this, no? Heat pumps can't heat up a large amount of water quickly (like resistive heating can). So if you have a solar peak at noon, where either yourself are producing cheap solar, or there's cheap solar on the grid in general, then you want to use that cheap energy to store heat for later use (like showers in the evening/morning).

So the way I see it, is that this material should be able to quickly store heat with the using the low temperatures that heat pumps provide, and be able to store it with minimal losses until it is needed.

>>jcattl+7r1
> Heat pumps can't heat up a large amount of water quickly

No, it's about temperature difference. My heat pump water tank heats about as quickly as resistive water tanks; but it could never heat to hundreds of degrees.