Vapor-compression refrigeration is the most common method of refrigeration, used in household refrigerators and air conditioners. It works by using a compressor to pressurise a refrigerant gas, causing it to evaporate and absorb heat.
Scientists from Berkeley Lab have developed a new refrigeration technique based on ionocaloric cooling, that is friendlier to the environment.
“The landscape of refrigerants is an unsolved problem: no one has successfully developed an alternative solution that makes stuff cold, works efficiently, is safe and doesn’t hurt the environment,” said Drew Lilley from Berkeley Lab. “We think the ionocaloric cycle has the potential to meet all those goals if realized appropriately.”
Ionocaloric cooling, is carbon-negative, as Lilley explained: “there’s potential to have refrigerants that are not just GWP [global warming potential]-zero, but GWP-negative. Using a material like ethylene carbonate could actually be carbon-negative, because you produce it by using carbon dioxide as an input. This could give us a place to use CO2 from carbon capture.”
The new method uses ions to create an endothermic reaction, which absorbs heat and causes a temperature decrease. To demonstrate the technique experimentally, the scientists used a salt made with iodine and sodium, together with ethylene carbonate, and managed a temperature change of 25 degrees Celsius.
Ravi Prasher, a research affiliate in Berkeley Lab said: “there are three things we’re trying to balance: the GWP of the refrigerant, energy efficiency, and the cost of the equipment itself. From the first try, our data looks very promising on all three of these aspects.”
The current refrigerators mostly use hydrofluorocarbons, or HFCs, which are potent greenhouse gases. 146 countries have signed an international agreement, The Kigali Amendment to gradually reduce the consumption and production of hydrofluorocarbons (HFCs), consequently to preserve and restore the ozone layer.