Imagine cooling your building with the same principle that kept Victorian-era icehouses stocked with lake-frozen blocks, but in modern form. That’s the idea behind ice batteries, a clever energy storage hack that’s been quietly slashing cooling costs across commercial buildings. The invention works by freezing water when energy is cheap, and using that stored cold later, they turn major power hogs (air conditioning, we’re looking at you) into more efficient, cost-effective systems.
Pioneers like Nostromo Energy and Ice Energy are refining the tech. Nostromo’s IceBrick modules pack 25 kWh of cooling capacity each, install on rooftops, and cost around $250 per kWh—about half the price of lithium-ion storage. Ice Energy’s Ice Bear 40 integrates with HVAC systems, shifting up to 95% of peak cooling demand to off-peak hours. And for homes, the Ice Bear 20 replaces traditional AC units while doubling as a thermal battery.
Unlike lithium-ion, ice batteries don’t degrade chemically – their water is endlessly reusable. Combining the technology with this hack, it’s even possible in environments where water is scarce. But the trade-off? They only store cooling energy. No frozen kilowatts for your lightbulbs, just an efficient way to handle the biggest energy drain in most buildings.
Could ice batteries help decentralize energy storage? They’re already proving their worth in high-demand areas like California and Texas. Read the full report here and let us know your thoughts in the comments.
Original photo by Kelly Sikkema on Unsplash
No it’s not. That’s about twice the cost of lithium ion battery cells.
https://about.bnef.com/blog/lithium-ion-battery-pack-prices-hit-record-low-of-139-kwh/
More to the point, since heat pumps move more heat than the input energy you supply, a kWh of batteries would run an AC for more than a kWh of cooling by a factor of 2-8 depending on circumstances, further dropping the cost for the same effect.
Of course the ice would be made by a heat pump in the first place, but for storage capacity a lithium battery would be both smaller, less expensive, and more readily retrofitted to existing systems, since all you need is a pass-through capable charger that throws the AC on to battery power when the grid prices go up. Basically a big UPS for your HVAC system.
At these prices, the difference in electricity cost between peak and low would need to be around 6 cents to break even. That’s easily exceeded with common time-of-use rates.
I installed such a system back in the ’90s in an office building. It was making ice during the night and cooling the building during the day, making use of the difference in both environment temperature and electricity pricing.
I also wonder what the charge rate is like. Ice doesn’t transmit heat well so the centre of a block of ice takes longer to form than the edges. Ice makers have a finger-like shape to increase surface area and reduce the maximum distance any bit of water can be from the cooling surface but this adds cost and volume overhead to an ice battery.
The ice battery should slow down significantly as it charges. Meanwhile lithium batteries will sustain 1C+ to high SoCs only tapering as they approach fully charged.
I remember a popular science article back in the day using slaked ice dumped into a tub.
It is indeed a nice application. I think its very similar to the concept of grid controlled load/heating, just done with heat pumps. I do not however like calling them ice “batteries” since the term is associated with using chemical reaction to generate electrical energy.
My father and I had been contemplating making a dimmer controller (RF and WiFi) for grid controlled load applications and selling them to electricity companies but it never materialised.
The pricing is rather sad – it is in the same ballpark as batteries already, but adding pumps and complexity. Limited to commercial nieches.
Why not just add the thermal battery directly? For example thick brick walls that cool down and keep the cold during the day. Better yet, have phase change material in the wall/floor, to keep temperature stable. Or add a “thermal battery” to the refrigerator.
NightHawkInLight did a lot on phase change materials. Is there a material for freezer/refrigerator temperatures? Add a thermal battery block and use cheap electricity to cool down, turn off when prices go high?
How much would you need?
The “fridge load shifting device” could just be a sheet of phase change liquid, with the thermostat tuned to the temperature. How much you’d you need for a day? At 200kJ/kg, this gives about 55Wh for a kg block of PCM. I found numbers around 0.5 to 1kWh/day for a fridge, so you would need 10-20kg of PCM to put in your fridge. Likely even more, as the COP of the heat pump requires storing morethermal heat than electricity. Better to put 1kWh of batteries next to it.
Commercially not viable for the home, seems better to use batteries.
Thick brick walls would cost quite a lot in comparison. The internet says $15-30 per square foot, so I would assume that’s how much extra you’d pay for doubling up the walls. It adds up quite quickly once you count how many square feet of walls you have.
I imagine one would get other benefits beyond thermal.
Yes, but you still pay more for it.
In addition to all the other reasons that this is marketing misinformation propaganda bull💩—
You still need power to generate the ice, and off-peak rates aren’t that massively different from on-peak rates. Typically < 20%.
We can’t just carriage the ice in from distant frozen lake beds, like Mr. Wu did for his meat locker?
A few years back I came across the German company Haase who tried to sell a water latent heat storage system. At least based on older heat pump tech, their product was not competitive.
Nothing about this is new, and it’s been possible for decades. The remaining qualifying aspect is whether or not a latent heat storage system pays for itself within its lifetime or not. More precisely this should be a geographical map showing years to amortisation based on local climate, PV generation and average price for installation, electricity, maintenance etc.
https://www.youtube.com/watch?v=fQtM-x4JVAo
“Please note that we have not been offering the ice storage system since the beginning of 2020. The market has turned out to be too small for the storage sizes we produce, and unfortunately it was not possible to offer a price that was acceptable for both the operator and us as the manufacturer.”
If my memory is correct Honeywell cooled one of their buildings with a gigantic block of ice. They had a building and in the winter when it was well below freezing they made the inside of the building one very large ice cube and thawed it out in the summer. The freezing was done by mother nature.
Sorry can’t remember any details and I always wondered how big an ice cube would be needed to cool a building – but I always gave them credit for trying something different.
So, one module of 25 kWh at $250/kWh is $6,250.
But 25 kWh is just a quarter ton of cooling storage. That’s 3 hours of operation for my relatively small 2t/d (24,000 BTU/h, 7 kW) household air conditioner. To get through a peak day’s worth of cooling I’d need 2-3 units. Though one unit would work for all but a few days per year.
Doesn’t seem worth the expense, but perhaps it would let me undersize my main unit and save money there, though.
“But the trade-off? They only store cooling energy”
Technically, if you have a cold reservoir in the presence of a higher ambient temperature you could rig up a thermoelectric generator unit (TEG) (like a peltier cooler but operating in get-energy-from-the-temperature-gradient mode) to get electrical energy out, the electrical energy can then power anything you desire… but it would be extremely inefficient.
This idea has been around since 1980 or earlier. Nuclear physicist Theodore B. Taylor was an early developer, as described in John McPhee’s “Ice Pond” (1981).
This is not “storage” of anything. This is an energy vacuum. Heat exchange. Your moving the heat out of the structure, but it’s just dumped into the atmosphere, and your counting on the atmosphere to have it’s own heat available when you need to reverse the exchange, but the atmosphere can be a little fickle about that, and the size of the energy vacuum you create is finite. This would be much more efficient if you had a fixed storage volume for the heat, but you would have to store a good bit more heat energy over that which the atmosphere can reliably provide, so that you have a reliable margin in either direction. Work done by a vacuum always has a bottom line, and you have to take time and energy to evacuate it again. So you build a building with a perfectly insulated heat core, and a perfectly insulated vacuum void, and you can spend minimal energy exchanging them, but the initial charge is expensive.
Before long, you’re looking for a source of energy that was already stored by nature to take advantage of, and suddenly we’re looking at nuclear not being that much more expensive.
Installing a box of ice on your roof, which will always be hotter than ground level (let alone in the ground) hardly seems like a good design choice. The only stength of the system seems to be using water, at least it won’t wear out from daily phase transitions (though the pumps and compressors…)
Don’t you need cooling exactly at that moment when solar cells produce the most energy – on hot, sunny days?
So I’d say it would make more sense to use a regular AC unit, and put up some solar cells to power it.
Would it require that much changes to fridges so that they could run off grid for at peak hours and recharge themselves later ?