Ever heard of HFO-1234yf? No? Well, give it time. You will. That random alphanumeric string is the trade name of a new chemical refrigerant (whose technical name is an even bigger mouthful, 2,3,3,3-tetrafluoroprop-1-ene) jointly developed by Honeywell and Dupont. And after December 8, when the Society of Automotive Engineers’ International Research Program endorsed it as the best answer to Europe’s new, stringent, and impending regulations governing mobile air conditioning (MAC) systems, HFO-1234yf looks to be poised to become the latest industry standard.
In June of 2006, the EU published its MAC Directive, announcing the phase-out, starting in 2011, of the relatively new automotive air conditioning refrigerant R-134a, in favor of systems or chemicals with global warming potentials (GWPs) below 150. (R-134a’s GWP is 1,430; HFO-1234yf has a GWP of 4. By definition, CO2’s GWP is 1.)
With this announcement, auto manufacturers, chemical companies, and environmental groups began scrambling to come up with the miracle solution that would be cheaper, cleaner, and more profitable for everyone involved. Two camps quickly evolved. The first backed a new variation on an old theme: fluorocarbons, stating that with a little research a new molecule could simply replace the old one already in use. Systems wouldn’t need to be redesigned, and companies could simply transition all of their manufacturing, worldwide, to save time and money. The second advocated a completely redesigned system based on CO2, claiming that the chemical is easily harvested from any number of industrial sources and that, in the long run, the planet and its people would be much healthier if a little extra effort is expended now.
The debate raged on, each side making slight gains only to lose them again in the ongoing tug of war. The latter group looked to be winning after several major German car manufacturers, including Volkswagon and BMW, announced they would be switching to a new MAC cooled with CO2. A video released to YouTube earlier in November of a car crash and several tests staged by the German Environmental Aid Association, amusingly enough with the German initials DUH, purported that the chemical was too hazardous for everyday use and didn’t hurt their cause either. But with the SAE’s announcement, coupled with the results the manufacturers solicited from a number of independent laboratories, the fluorocarbon may have just jumped ahead again.
According to the information posted by Honeywell and Dupont, independent testing confirmed that while HFO-1234yf’s global warming potential may be slightly higher than that of CO2, it is significantly more efficient, particularly in hotter climates where air conditioning is more widely used. Since car air conditioners are powered by their engines, current CO2 cooled systems actually require more fuel than the new synthetic fluorocarbon, leading to greater indirect emissions and thus a larger environmental impact. What is more, only minor modifications would be needed to use HFO-1234yf in the current fleet of vehicles crowding the roadways. CO2 systems have to function at significantly higher pressures to cool effectively and thus require significant re-engineering — not to mention additional safety features to guard against failures.
CO2 advocates point out that the new chemical is not only toxic, like R-134a currently in use, but also flammable, unlike its counterpart. HFO-1234yf’s supporters have responded with tests stating that HFO-1234yf breaks down into safer constituents in a matter of days; other tests claim the chemical posed no significant risk in real world scenarios. Mirroring their opponents’ tactics, they then returned fire questioning the safety of pressurized canisters of CO2 in car accidents.
And so it goes. With the exception of the German companies, no doubt heavily influenced by German popular opinion and the government tax breaks, which is heavily biased in favor of CO2, none of the major manufacturers have claimed sides. But one thing is certain, given the current fiscal positions of car companies around the world, R&D costs are likely to play a major role in whatever choice they finally make. And right now, HFO-1234yf is the cheaper alternative.
I’m adding a link to the YouTube video here, but unless you speak German, you probably won’t get much out of it.