My local power company worked with a bunch of businesses in my town to install these rather than upgrade the dead end line for a few peak periods.

How long ago was this? The idea seems simple enough and would really benefit from the increasing glut of renewables. Even better, unlike a sand battery, you can potentially cycle it for several months of summer, by offsetting consumption by just a few hours feels like it could be economically viable.

Then again, the competition is general purpose batteries which can be used all year and probably require less maintenance.

Just because something seems like should work doesn't mean it will. Air conditioners are simple and cheap to install. An insulated swimming pool in the basement is not.

1 cubic meters of water chilled 10C below ambient is 40MegaJoules of energy.

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.

Air conditioners have a COP of about 3 though. So really its more like 3.5kwh of storage. If you want to go lower temperature to store more then your COP drops.

The temperature delta is the hard part for me to estimate here.

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.

Typical residential air conditioning is using 4kW of power. So your 40MJ of energy would be used up in 40MJ/4kW=10000 seconds, or just 3 hours. And its only theoretical, because it assumes 100% efficiency in storage and conversion

It's odd how often battery enthusiasts don't understand the difference between energy and power.

> Air conditioners are simple and cheap to install

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.

And tomorrow because when you want to cool your house the sun is most likely out.

It definitely seems economically viable to me

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.

This has been around for a long time. The Detroit VA hospital used it, I believe with tanks under the parking structure. I also believe there were problems related to the maintenance of the tanks.

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.

If you’re using renewable energy that would otherwise go to waste for lack of storage, then that’s definitely saving (useful) energy.

Energy is (sometimes) free, or even negative priced (!!!!).

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.

You're confused, negative prices are not driven by techincal limitations. Solar, and especially hydro, and even nuclear can shut down just fine.

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.

> In either method there will exist prices which are negative to the market but positive to the producer.

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.

IceBear was competing directly with ever cheaper PV.

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.

Nope.

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.