Cheap electricity can make cold, and then a fan can convert the cold water into cold air during peak hours when electricity was costlier.
Fans still took electricity to run, but it'd only be a few hundred watts to run air-conditioning rather than kilowatts of power.
Then again, the competition is general purpose batteries which can be used all year and probably require less maintenance.
Or in other words: 11kW-hrs of cooling, comparable to an entire Tesla Powerwall.
We aren't talking about entire swimming pools here. Just a few cubic meters of water. Shift the temperature delta as you see fit but... It's actually very space efficient.
I know that IceBear left the water around 45F, so take that for what you will.
Either way, we aren't talking about entire swimming pools here. Just a small, single digit number of cubic meters of water.
Today. In my chats with the sort of home improvement types that seem to be in this thread, we're less concerned with today and more concerned with the cost of things in the future, as societies include "climate taxes" (in the form of actual taxes, subsidies, or whatever else) in the cost of things.
I'm hoping someone recreates it. It's just a few fans, a tub of water, a pump, and a slightly modified heat pump/air conditioner unit that can safely run down to 50F or so.
It's already viable for stadiums and other public events.
But the important aspect is that this is a cost saving technique, not an energy saving one. You’ll spend more energy because of the thermal losses of the tanks, but hopefully it is more than offset by the cheaper electricity rate.
As it turns out: it's economically infeasible to turn off solar panels, wind, nuclear and sometimes Hydro (depending on water rights, it may be illegal to store water/energy at a water dam).
In all of these cases, the energy is 0 cost or even negative cost.
Solar and Wind instead drive prices negative because they have subsidized contracts. Each country is slightly different in implementation, between Feed-in-Tarif vs Feed-in-Premium. In either method there will exist prices which are negative to the market but positive to the producer.
Thus if you cannot plan long term to rely on negative prices. Those FIT schemes around the world are transforming into FIP, and the FIP premiums are getting lower and lower. Negative pricing in electricity markets will go away in a decade or two. This isn't magic or even special, solar is succeeding which means the subsidies are getting weakened.
Curtailing solar production is not a big deal. How many existing plants have grid operator directed shutoffs depends on your market. In Japan as of 2024 all new non-rooftop solar has it. Prior to 2020ish only Kyushu and Kansai regions required it. Now Tepco, Hokkaido, and Touhoku require it for new contracts. There are still a couple old contracted plants getting developed this year, but those are rarities.
And that's only Japan, which itself does not have a super strong duck curve yet: http://jepx.org/ Regions like California have had extreme duck curves for ages. While duck curves are a big worry for internet commentors, they've been points of discussion for grid operators are a lot longer. Hence the move to Feed in Premiums which will slowly make the duck curve a solar operator's problem and not a tragedy of the commons situation.
I'm talking about running air conditioners extra hard during low market prices (which includes free and/or negative priced periods of energy), and then storing that cooling power in single-digit cubic meters of water.
Negative market prices of electricity absolutely applies to this case.
It's a tech for time shifting cheap overnight energy to the expensive daytime.
Installing PV gives you cheap power directly and correlates with air-con demand.
You still need aircon at 7pm after the sun begins to set and while solar is losing power.
Cooler temperatures aren't until 10pm or so, hours after sunset.
Since you burn the wood really fast, you need to delay that heat release. That's where sand comes in as a cheap and good enough material. There are also systems that heat water and store it in a tank, which also make sense if you want hot water in your house too.
Sand is really only useful here because that much clay is usually significantly more expensive and would take forever to dry out.
Source: researched the shit out of and have built a rocket stove.