Before electric refrigeration, preserving food meant transporting large ice blocks over long distances. Today, a closed‑loop system of pipes filled with refrigerant chemicals absorbs and radiates heat, a reliable method that comes with high energy demands and the use of environmentally harmful chemicals.
In 2023, researchers at UC Berkeley introduced the ionocaloric refrigeration cycle, a concept that revisits the humble phase change of water. When ice melts, it absorbs heat; when liquid water freezes, it releases heat. By orchestrating these transitions inside and outside a container, the system can chill the interior while dissipating heat externally.
Achieving in‑house ice melting is key. The team added charged ions—salt—to lower water’s freezing point, a principle already used in sea‑water desalination. An electric current injects ions while the water is inside the chamber and extracts them when it’s outside, allowing the water to melt inside, absorb a few degrees of heat, then freeze and radiate that heat away.
According to a recent interview with Berkeley Lab News, co‑author Ravi Prasher outlined three goals: lower cost, boost energy efficiency, and reduce global warming potential. The prototype relies on common ingredients—purified water, iodine, and sodium—making it highly affordable.
Initial tests demonstrated a temperature swing of 25 °C using only 0.22 V. While the design is still in the laboratory stage, such low electrical requirements hint at a future that could outpace conventional refrigerators in energy consumption.
The refrigeration sector accounts for nearly 8 % of global greenhouse‑gas emissions, largely due to the electricity needed to keep appliances running. Replacing high‑pressure hydrofluorocarbon gases (e.g., R134a, R410a) with a salt‑water cycle eliminates leaks of potent greenhouse gases. Furthermore, the researchers tested adding ethylene carbonate, a compound that absorbs CO₂ during manufacture, suggesting that future units might even sequester carbon from the atmosphere.
