By Modern life depends on air conditioning and refrigeration—but the chemicals that make cooling possible often come with environmental costs. Now, researchers say they may have found a different way to make things cold.
Scientists at Lawrence Berkeley National Laboratory have developed a new refrigeration method, ionocaloric cooling, which could offer a safer, more environmentally sustainable alternative to traditional cooling systems, according to new reports.
Most modern refrigeration relies on vapor compression. In that process, a refrigerant evaporates to absorb heat from a space and then condenses elsewhere to release it. The system is effective but environmentally costly: many refrigerants, particularly hydrofluorocarbons (HFCs), have high global warming potentials and contribute significantly to climate change.
Ionocaloric cooling takes a different path. Instead of relying on evaporation and compression, it harnesses the heat absorbed or released when a material changes phase—similar to how melting ice draws warmth from its surroundings.
But rather than raising the temperature to trigger the phase change, the system introduces ions from dissolved salts, shifting the material’s melting point and forcing the transition. The result is a cooling effect.
“The landscape of refrigerants is an unsolved problem,” said mechanical engineer Drew Lilley from the Lawrence Berkeley National Laboratory in California.
“No one has successfully developed an alternative solution that makes stuff cold, works efficiently, is safe, and doesn’t hurt the environment. We think the ionocaloric cycle has the potential to meet all those goals if realized appropriately.”
Early modeling suggests the ionocaloric cycle could match—or even outperform—traditional refrigerants in efficiency. In laboratory tests, the Berkeley team applied a small electric current—less than one volt—to move ions through a system containing sodium iodide salt and ethylene carbonate, a widely used organic solvent that can be produced using carbon dioxide as a feedstock.
The setup produced a temperature change of roughly 25 °C (45 °F), outperforming several other emerging caloric cooling technologies.
Researchers say the key challenge is balancing environmental impact, efficiency, and cost.
“There are three things we’re trying to balance: the GWP of the refrigerant, energy efficiency, and the cost of the equipment itself,” said mechanical engineer Ravi Prasher from the Lawrence Berkeley National Laboratory.
“From the first try, our data looks very promising on all three of these aspects.”
The system’s chemistry could also provide a climate advantage. Because ethylene carbonate can incorporate CO₂ during its manufacture, the overall system could theoretically achieve a global warming potential of zero or even negative.
Such a development would support international efforts to phase down HFC refrigerants, including commitments under the Kigali Amendment, which calls for at least an 80 percent reduction in HFC production and consumption in the coming decades.
Researchers are now testing different salt combinations and system designs to improve performance. In 2025, an international research team demonstrated a related high-efficiency approach using nitrate-based salts regenerated through electric fields and membranes—an avenue the Berkeley group had anticipated.
“We have this brand-new thermodynamic cycle and framework that brings together elements from different fields, and we’ve shown that it can work,” said Prasher.
“Now, it’s time for experimentation to test different combinations of materials and techniques to meet the engineering challenges.”
The foundational research was published in the journal Science. While ionocaloric cooling remains in the research stage, successful scaling could eventually lead to practical heating and cooling systems for homes, businesses, and industry.
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