It's been two years since 84 countries jumped on the Kyoto Protocol bandwagon, which calls for almost a total elimination of all greenhouse-producing emissions, including hydroflourocarbons (HFCs). This has caused the auto industry to reassess its standard coolant — HFC-134a.

Considerable research by automakers, universities and engineers has gone into the viability of carbon dioxide (CO2) as a replacement refrigerant. The rub — CO2 features prominently in the “basket of gases” banned by the Kyoto Protocol.

With the Society of Automotive Engineers (SAE) hosting a four-day Alternative Alternate Refrigerant Systems Symposium in Phoenix, AZ, July 11-13, many questions remain nebulous concerning the use of CO2 as a renewable refrigerant source.

WEVTU speaks with Ward Atkinson, chairman — SAE Air and Climate Control, about how far along CO2 has come and how far it has to go before CO2 becomes the industry standard refrigerant.

The outlook is not promising.

Originally, it was thought that CO2, being a primary emission of the internal combustion engine, could be re-circulated from the tailpipe back through heating and cooling systems, replacing the ozone-depleting hydrofluorocarbon HFC-134a. As it turns out, the industry is much further away from CO2 being a viable alternative for HFC-134a than anyone — including SAE engineers studying the problem — had believed.

Mr. Atkinson stresses that greenhouse-gas emissions from automotive cooling systems make up a mere 2% of the earth's total greenhouse emanation. He also is skeptical about the practicality of CO2 use in automobiles. “Early studies show that CO2 could be more efficient in vehicles (than HFC-134a) at 77°F (22°C).” However, when the ambient temperature begins to rise or fall from that narrow mark, the systems lose efficiency.

This means that burgeoning markets such as China would not produce any beneficial emission reductions. To be effective, CO2-based HVAC systems would have to be regulated to climates that continuously hover around 77°F.

Mr. Atkinson tells WEVTU that the hundreds of billions of dollars spent on updating R-12 systems to HFC-134a systems would be “a pinch of salt compared to going to CO2” and that “retrofitting” is not an option. The high pressure required for CO2-based HVAC systems would make current hoses, seals and compressors incompatible.

Nevertheless, research continues into CO2 as an alternative mobile refrigerant. Mr. Atkinson points to European markets as the driving force behind this initiative and is quick to note that some German engineers, in particular, are the most strident advocates of CO2 research, saying, “The nucleus of CO2 activity is in Germany.”

The catch, as it stands, is that the U.S. and Japan (which both remain the largest players in the coolant market), HFC-134a standards are superior. Mr. Atkinson points to those countries' tremendous industry and government efforts to reclaim, recycle and regulate HFC-134a, adding that technician training throughout the U.S. and Japan is what other countries may want to shoot for instead of a conversion to CO2.

There is another problem — suppliers must adapt to the change. At the recent Global Powertrain Congress 2000 in Detroit, WEVTU speaks with Sam Bianchi, formerly with the Livernois Group, who now advises Vehicle Thermal Management Llc. (VTM). Mr. Bianchi points out, “There are a lot of companies developing heat exchangers (necessary for CO2 cooling) and a lot of action worldwide.”

Mr. Bianchi adds, “I think it's going to happen eventually because of the environmental aspect.”

The hundreds of billions of dollars spent on updating R-12 HVAC systems to HFC-134a would be “a pinch of salt compared to going to CO2” — and retrofitting is not an option.

Certainly VTM thinks so as well, as the company already is in the development stage with two compressor manufacturers.

“It's definitely going to be an advantage for suppliers who are onboard with CO2,” says Mr. Bianchi.

This is part of the reason for the SAE symposium. Suppliers who aren't CO2-competitive will be left out in the heat when even the smallest of niche automakers begin shopping for parts.

The SAE symposium, now in its third year, is attempting to create a set of standards or a common system of gas-cooled condensers and evaporator sizes, in addition to a pre-competitive agreement on materials and specifications for pressure lines and seals — a matter that remains up in the air.