NIST Quest for Climate-Friendly Refrigerants Finds Complicated Choices
Researchers at the National Institute of Standards and Technology (NIST) have just completed a multiyear study to identify the “best” candidates for future use as air conditioning refrigerants that will have the lowest impact on the climate.
Unfortunately, all 27 fluids NIST identified as the best from a performance viewpoint are at least slightly flammable, which is not allowed under U.S. safety codes for most end uses. Several fluids among the list of refrigerants are highly flammable, including propane, the fuel for outdoor grills.
In other words, the NIST study found no ideal refrigerant that combined low “global warming potential” (GWP)—a measure of how much heat a gas will trap if released into the atmosphere— with other desirable performance and safety features such as being both nonflammable and nontoxic. The results appear in Nature Communications.
“The takeaway is there is no perfect, easy replacement for current refrigerants,” NIST chemical engineer Mark McLinden said. “Going into the study, we thought surely there has to be something else. Turns out, not so much. So it was a bit surprising, a bit disappointing.”
Photo credit: Achim Hering via Wikimedia Commons