A new eco-friendly cooling device can reach temperatures as low as -12℃. The device, which does not use greenhouse gas refrigerants, is the first such system in the world to reach sub-zero Celsius temperatures.
Researchers at the School of Engineering of The Hong Kong University of Science and Technology (HKUST) reported the new elastocaloric cooling device in the journal Nature. “This work pushes the elastocaloric technology one step further into the sub-zero Celsius freezing region,” they write.
Hunger and food waste are two big problems around the world. Freezing food could help solve both. Refrigerating just 12% of the produce that goes to waste every year due to spoilage would feed an estimated 1 billion more people.
Preserving food also prevents the emissions from tossing food into landfills. Food loss and waste also account for 8–10% of global greenhouse gas emissions, according to the United Nations.
But cooling food comes with its own environmental footprint because of the technology used today. Refrigeration uses about 20% of global electricity, and today’s vapor-compression technology depends on refrigerants that have high global warming potential.
In recent years, researchers have been trying to develop cooling methods that are energy-efficient and that do not use greenhouse gas refrigerants. Elastocaloric cooling is one such technology. It relies on the temperature change of materials called shape memory alloys (SMAs) when they are stretched and released.
But past cooling devices have not had enough cooling power for commercial use. The HKUST team developed a device that uses a new type of solid refrigerant, a nickel-titanium alloy with a higher nickel ratio. They also use calcium chloride as the working fluid that transfers heat away for cooling. Their design connects multiple alloy tubes together for a cascading effect that amplifies cooling.
In outdoor tests, the desktop device cools a surface down from 24°C to -12°C, and froze water in two hours. Sun Qingping, the mechanical and aerospace engineering professor who led the work, said in a press release that the researchers plan to increase the system’s efficiency and make it more cost-effectiveness by using advanced shape memory alloy materials and trying different system designs.
Source: Guoan Zhou et al. Sub-zero Celsius elastocaloric cooling via low-transition-temperature alloys, Nature, 2026.
Image by Sasha T./Envato
