The world could avoid a 0.09°C rise in global temperatures before the end of the century by switching to using propane as a refrigerant in air conditioners, according to a new study from the International Institute for Applied Systems Analysis (IIASA), the UN Environment Programme (UNEP) and the University of Leeds.
If the current trends in global temperature rises continue, the energy demands of space coolers will more than triple by 2050. Aside from the rise in energy consumption, space coolers also threaten the environment by using halogenated refrigerants with high global warming potential.
Split air conditioners (split ACs) that use an indoor and an outdoor air unit connected by pipes are the most common appliances used for space cooling. They typically use HCFC-22 and HFC-410 as refrigerants, both of which have substantial global warming potential, with scores of up to 2,256 – meaning that they trap up to 2,256 times more heat than carbon dioxide over 100 years. Many manufacturers are looking for alternative refrigerants with lower global warming potential, such as HFC-32. However, with a global warming potential score of 771, HFC-32 still poses a significant climate hazard.
In the study published in Proceedings of the National Academy of Sciences of the United States of America, researchers used IIASA’s Greenhouse Gas – Air Pollution Interactions and Synergies model to compare the baseline halogenated refrigerant emission scenarios with scenarios of switching to HFC-32 or propane. Although the switch to HFC-32 reduced the global temperature rise (0.03°C by the end of the century), using propane proved to be the more sustainable solution.
“Propane exhibits significant environmental advantages through good energy performance and a global warming potential of less than 1,” IIASA researcher Pallav Purohit said in a statement. “In split-ACs up to 7kW, propane can be classified as a technically valid alternative to HFC-driven split-ACs.”
Energy-efficient split ACs using propane are already commercially available in China and India. Although they perform similarly to split ACs using HFC-32, and even better than appliances using HFC-410A and HCFC-22, some national regulations prohibit their use because of propane’s higher flammability, which is hampering their wider adoption.