"Replacing HFCs as a coolant is the goal of a global accord, but so far, economical alternatives all show some flaws."
"When nearly 200 countries agreed last October to dramatically reduce their reliance on climate change-polluting chemicals called hydrofluorocarbons (HFCs) in air conditioning and refrigeration, the hunt for alternatives was already underway. Now, a new study in the journal Nature Communications that comprehensively explored pure liquid options found only 27 candidates, and problems with all of them.
For this study, researchers spent years reviewing millions of pure liquid candidates to replace the refrigerants widely used in small-scale air conditioning, a major source of greenhouse gas emissions. After accounting for various factors including their global warming potential (GWP), toxicity, energy efficiency and flammability, the pool of options had narrowed to 27. The most promising of these options were at least slightly flammable, the researchers found. They also suggested additional replacements could come from blending chemicals, a more expensive alternative that some companies were already pursuing.
'There are no perfect options for low GWP refrigerants,' said Mark McLinden, the study's primary author and a researcher at the Colorado-based National Institute of Standards and Technology. 'There are tradeoffs—and the biggest tradeoff is [between] GWP and flammability.'"