In the early days, perhaps up to the 1950s or so, Ice was your standard cooling solution. If you didn’t have a refrigerator, you had an ice box. This solution wasn’t as on-demand as modern AC, but it had a nice benefit: no high electricity bills. Every summer as we turn to AC to avoid sweating to death, we’re faced with our soaring cooling bills. With this in mind, some manufacturers actually still use ice in HVAC systems today.
Prior to the invention of air conditioning, ice was pretty much the only cooling thing available. Today, we have a million and one ways to cool things, but they don’t entirely hold up to ice. Water by itself is amazing at storing and conducting energy. Just think of the last major snow storm and how long it took for that to melt off afterwards. North of Philly here, our last major storm dropped eight inches or so that actually stuck to the ground and it took days of 50+ degree weather for it to melt.
This makes Ice an excellent way to store “coolness”. On top of that, water is non-toxic, abundant, easy to store, and easy to cool. The other famous alternative might be liquid helium or liquid nitrogen, both of which are used in industrial cooling applications such as MRI machines and particle accelerators. The problem is that they’re not easy to cool, can involve vast pressures to cool, and aren’t as safe. The safest chilling-battery is just ice.
We can use ice as a battery to store coolness, negative-energy, to later cool down a facility. A building with a water-chiller can bypass the chiller, pass the water through a heat-exchanger in contact with the ice, and cool the building without needing to burn electricity during the daytime or even remain cool during a power outage so long as their backup generators can power a few pumps.
Big Industry is Buying Ice?
The genius of this is that commercial operators aren’t using giant swamp coolers or buying all-natural, pure arctic glacier ice. We can make ice when it’s cheap, and use it when it would be prohibitive to run an air conditioner. Commercial operations are often charged a different rate for electricity based on the time of day or the demand on the electrical grid.
We can imagine a kilowatt of power might cost $1 between noon and 6pm. Between 6pm and midnight it might cost $0.80, and from midnight to noon, it costs just $0.20. If you run your power hungry AC during the day, it’s going to get expensive. If you run it at night, it won’t, but you really can’t store cold-air that well and you’d only make your customers miserable if the store interior was below zero. It is however, possible to create giant piles of ice to use for cooling later. We put all that cooling energy into ice at 1/5th of the cost overnight, the ice-generator runs more efficiently in the cool night-time air, and on the whole we’re running cheaper and more efficient.
Ice and AC Don’t Mix
Well, most of the time ice and AC don’t mix. When hardware is built with ice in mind however, it’s an easier sell. These industrial chillers with ice-storage will generally just have a chiller next to some ice tanks, and push the water through those tanks. As long as the circulatory water isn’t left to sit in the tank, it won’t freeze. The rest of the system just has to be designed to accomodate the ice-detour and have some other accomodations.