Cooling without harmful gases: KIT review shows how far caloric cooling devices have come
Materials that heat up under a magnetic field, electric field, pressure or strain could enable air conditioning without harmful refrigerants. A review in Nature Energy cites first prototypes above 3 kilowatts.
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Air conditioners and refrigerators today mostly use refrigerants that can contribute strongly to global warming. One alternative is so-called caloric cooling: certain materials heat up when a magnetic field, an electric field, pressure or strain acts on them, and cool down once the stimulus is removed. Devices use this effect to move heat – much like a refrigerator.
A team led by Dr. Jingyuan Xu of the Institute of Microstructure Technology at the Karlsruhe Institute of Technology (KIT) and international partners has summarised the state of the art in a review in the journal Nature Energy (DOI 10.1038/s41560-026-02143-1), published on 30 October. According to the review, magnetic-field-based systems already exceed 3 kilowatts of cooling power, and mechanically driven prototypes have passed 1 kilowatt.
"It does not require refrigerants with a high global warming potential," Xu says of the technology. "The material can show large temperature changes in the laboratory," says first author Dr. Nun Wang – what matters, however, is how efficiently the effect can be used for cooling in a device. According to Xu, the technology will first be of interest where conventional cooling reaches practical limits. According to KIT, energy demand for space cooling is expected to more than double by 2050.