'Electrocaloric' heat pump could transform air conditioning

That 20K temperature difference will need some work. Maybe for hydronic floor heating or ceiling cooling under very mild conditions with excellent heat exchange on the exterior side, but for serious use, it’s not enough.

So I guess the idea would be a multistage device? Very cool if it works and can be made without too many moving parts.

I think that any really big reduction in refrigerant use will a side effect, though. Sure, modern A/C equipment has some refrigerant in it, but there is a lot of refrigerant in the often-fairly-long pipes between the indoor and outdoor equipment. Electrocaloric heaters (or gas-fired heat—and-hot-water devices or thermoacoustic devices or district heating or much any other fancy technology) will replace indoor refrigerant pipes with water pipes, which are messier if they leak but are otherwise quite environmentally friendly.

This could be done today with no exotic tech at all. Just use an outdoor unit with a small sealed refrigerant system, perhaps using propane or CO2 or just less fluorocarbon or HFO refrigerant, and use indoor PEX water pipes to indoor fan coils. Some light regulation could nudge new construction in this direction. You can buy systems along these lines today. Bonus points for the fact that such a system could quite easily control the cooling coil temperature to adjust dehumidification rates.

Here's the author's web site.[1] Not finding a relevant paper.

2020 paper from MIT on this subject.[2] It works, but, as yet, is a small-sized effect. Think chip coolers, not house coolers.

[1] https://pace.uni.lu/emmanuel-defay/

[2] https://fisherp.mit.edu/wp-content/uploads/2020/10/129.full_...

> The use of environmentally damaging gases in air conditioners and refrigerators could become redundant if a new kind of heat pump lives up to its promise. A prototype, described in a study published last week in Science [1], uses electric fields and a special ceramic instead of alternately vaporizing a refrigerant fluid and condensing it with a compressor to warm or cool air.

"High cooling performance in a double-loop electrocaloric heat pump" (2023) https://www.science.org/doi/10.1126/science.adi5477

Electrocaloric effect: https://en.wikipedia.org/wiki/Electrocaloric_effect

Sounds promising - Eliminating a compressor should make them much quieter than noisy heat pumps and a/c - this is their biggest problem I think.

They harp a lot on the environmental issues of current refrigerants as a value proposition for this new device. I think that logic makes sense with older refrigerants, but R744 they are literally using CO2 as the refrigerant. Of course CO2 is a greenhouse gas, but in this usage it effectively acts as sequestration. Seems like that is already a really good solution from a climate impact perspective

With no pressure, I guess such systems would last longer than current heat pumps.