Engineering360: "What is the ideal refrigerant?"

This article gives a very good summary of the state of affairs today, in my opinion. The use of TEWI makes a great deal of sense. However, it does require educated assumptions regarding the amount of accidental release of refrigerants. The chart for TEWI did not include R134A. Since it is used in significant mobile applications, I would expect it to have a much higher ratio of released refrigerant than R410A, which was included. From that assumption, I would expect a much higher "direct" impact on global warming from R134A. It would be interesting to see what the TEWI rating is for that.

I do not work directly in this field but have a very keen interest and it appears that R744 is not part of this evaluation is this because of the pressures? From my research CO2 R 744 was the original refrigerant and popular up until the invention of the fluorocarbons. R744 outside of the pressure is safe, non flammable, quick heat recovery and release. Boils at -78 F and for my purpose it is ideal in many qualities. Comments appreciated.