A recently published study by the International Institute for Applied Systems Analysis (IIASA) in Vienna found that adopting propane (R290) in split air conditioners (ACs) worldwide would reduce global warming up to 0.12°C (0.22°F)

Split ACs are the most common residential cooling equipment worldwide. Not only are they energy intensive (requiring up to 10% of global electricity in 2016, as the study reports), but they are also commonly charged with high-GWP f-gases scoring hundreds or thousands times more than carbon dioxide, both on a 100-year and 20-year GWP perspective.

Split ACs are estimated to reach 3.7 billion units in 2050 if the current trend continues, with mainly Asian countries driving this growth, the study reports.

The authors of the study deployed the modelling tool GAINS and reached the conclusion that “a switch to propane as an energy-efficient and commercially available low-GWP alternative in split ACs” could avoid an average of 0.09°C/0.16°F (0.06 to 0.12°C/0.11 to 0.22°F) increase in global temperature by the end of the century. This, they stress “is significantly more” than the average of 0.035°C/0.063°F (0.02 to 0.05°C/0.036 to 0.09°F) avoided warming from a complete switch to HFC-32 in split ACs.

“Leapfrogging from HCFC-22 or HFC-410A units to high-efficiency appliances using propane reduces energy consumption and GHG emissions and thus provides a significant opportunity to contribute to national climate action plans,” the study explains.

The study was published on August 15, 2022, in volume 119, No. 34 of the Proceedings of the National Academy of Sciences of the United States of America (PNAS).

Source: Purohit, P., et al., (2022). The key role of propane in a sustainable cooling sector.

In another recent study produced by the IIASA, the same author, Pallav Purohit, reported that modelling exercises showed Kigali Reductions targets not compatible with the goals of the Paris Agreement, and called for steeper reductions of HFCs worldwide.  

The importance of 0.12°C

The Paris Agreement calls for countries to limit global warming to well below 2°C and pursue efforts to limit it to 1.5°C (2.7°F) above pre-industrial level (1850-1900). Thus switching to propane in ACs would have a significant mitigating impact on global warming.

The International Panel on Climate Change (IPCC) has confirmed that the world has already warmed 0.87°C/1.6°F (±0.12°C) during the decade 2006-2016 relative to pre-industrial level due to anthropogenic emission of GHGs. Given the current 0.2°C/0.36°F (±0.1°C) rise per decade “human-induced warming reached 1°C (1.8°F) above pre-industrial levels around 2017 and, if this pace of warming continues, would reach 1.5°C around 2040.”

Source: IPCC

Natural refrigerants-based heat pumps

A recent study conducted by ATMOsphere (publisher of this outlet) showed the technology readiness of natural refrigerant-based heat pumps and ACs across Europe.

Many companies are already producing this equipment and marketing it successfully. The expected prohibitions in the proposal of the EU F-gas Regulation targeting these HVAC&R sectors would accelerate the deployment of this technology and support substantially the EU’s climate goals.

In addition, the recently revised IEC 60335-2-40 Ed. 7 would also support the uptake of propane in household air conditioners, heat pumps and dehumidifiers by allowing higher charges (hence higher capacities of the equipment) once additional safety measures are implemented.

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