Earth-Friendly Cool Cars In 2011

Big changes are under way in automotive air-conditioning that could add anywhere from $40 to more than $1,000 to the price of a new car with air-conditioning. Leading the way is the European Community, whose Parliament voted in June to phase out HFC-134a, the workhorse hydrofluorocarbon refrigerant used in virtually all automotive air conditioners today.

The trouble with HFC-134a is that when it leaks from air conditioners during use and servicing, the refrigerant becomes a gas that scientists believe contributes to global warming and climate change. In fact, it has a global warming potential 1,300 times more powerful than an equivalent amount of CO₂, the standard measure of global warming gases.

As part of a long-term commitment to reduce emissions of global warming gases under the Kyoto Protocol to the United Nations Framework Convention on Climate Change, the 25 European Union countries have now agreed to ban HFC-134a in new cars beginning in 2011. In addition, the EU will ban use of HFC-134a as well as any other fluorinated gas with a global warming potential greater than 150 in all vehicles in 2017.

Because the U.S. has not ratified the Kyoto protocol, carmakers aren't under immediate pressure to switch to alternative refrigerants for cars sold in the U.S. market. However, the European requirements are forcing all automakers to consider a switch to avoid the inventory and servicing headaches associated with supplying and maintaining a variety of air-conditioning systems.

Automakers, component suppliers, and refrigerant manufacturers, including DuPont, Honeywell, Arkema, and Ineos, are now searching for alternatives to HFC-134a. Ironically, the most likely replacement candidate for HFC-134a at this time appears to be CO₂. Component suppliers such as Visteon, Behr, Obrist, and Valeo have already developed air-conditioning systems that use CO₂.

Suppliers of fluorochemical refrigerants will have to rush to catch up if they intend to qualify replacement candidates for use in car air-conditioning systems in Europe by 2011. In February, Honeywell and DuPont identified fluorine-based replacements with low global warming potential that could work in systems designed for HFC-134a with some tweaking. Visteon has also demonstrated an air-conditioning system using Honeywell's candidate, dubbed Fluid H. Arkema and Ineos say they are working on replacement candidates, too.

This is not the first time that environmental regulations have forced automobile makers to switch refrigerants. In the mid-1990s, the industry switched from CFC-12, a chlorofluorocarbon that depleted upper atmospheric ozone, to HFC-134a, a gas that does not deplete ozone. Governments worldwide endorsed the switch under the 1987 Montreal Protocol on Substances That Deplete the Ozone Layer.

According to DuPont, the switch also brought with it an important secondary benefit. The transition from CFC-12 to HFC-134a brought with it an approximately 85% reduction in contribution to global warming from car refrigerants. But that is still not enough for EU countries, which have committed to achieving an 8% reduction in emissions of greenhouse gases in the period from 2008 to 2012 compared with 1990 levels.

A report from the United Nations Intergovernmental Panel on Climate Change says the potential damage from fluorinated gases−including emissions from refrigerators, air conditioners, fire extinguishers, and insulating foam−has declined significantly since 1990 (C&EN, May 2, 2005, page 28). Back in 1990, worldwide fluorocarbon emissions had the same global warming potential as 7.5 billion metric tons of CO₂. Those emissions were equivalent to about 33% of the CO₂ produced by fossil-fuel burning. By 2000, global fluorocarbon emissions had declined to the equivalent of 2.5 billion metric tons of CO₂, equivalent to about 10% of CO₂ produced from fossil fuel.

Despite the improvement, the European Community is adamant about the need to reduce emissions of fluorinated gases. It argues that, although fluorinated gases account for just 2% by volume of EU greenhouse gas emissions, the global warming potential of the many variants now in use is still too high. So in addition to the limits placed on automotive air conditioners, the community has also placed restrictions on sulfur hexafluoride used in electrical transmission systems and perfluorocarbons used in fire extinguishers.

Because of their use in moving vehicles, auto air conditioners pose special challenges in their design, says Fred Sciance, environment and energy manager at the public policy center of General Motors. The systems must be small enough to be crammed under car hoods, and they must also be light enough to minimize the energy needed−and the CO₂ produced to make the energy−just to haul them around. They must also endure road vibrations, corrosion from road salt, and other environmental insults.

HFC-134a is especially valuable as an auto refrigerant, Sciance points out, because it is nontoxic and nonflammable, attributes that are important in case an air-conditioning system leaks after a crash. Any substitute for HFC-134a must have those two important characteristics, he says.

For Sciance, the EU ban poses a real dilemma. For safety reasons, a number of standby substitutes now available are not really suitable, he says. HFC-152a, with a global warming potential of 140, is compatible with HFC-134a systems, but it is slightly flammable. In litigious societies, such as the U.S., it is not a good choice. Propane, referred to as R-290 in the industry, has a global warming potential of 11. However, it is a flammable gas and so is unacceptable.

Sciance argues that "there is no compelling reason to move away from HFC-134a on environmental grounds." Any leaks that do occur from HFC-134a are offset, he says, by the environmental benefits obtained from the low energy use of such systems. He concedes that CO₂ systems might be slightly more beneficial to the environment in the cooler climates of Northern Europe, but they bring other complications.

For one, Sciance says, CO₂ systems work at much higher pressure than do systems that use HFC-134a. They require more energy to operate. In addition, high-pressure systems are likely to leak more readily than would low-pressure HFC-134a systems. He worries that leakage and the need for frequent recharging of the system would lead to customer dissatisfaction.

"CO₂ systems may be the answer for Europe, but they may not be right elsewhere," Sciance says. If CO₂ systems turn out to be more costly or more troublesome, the automobile manufacturer might end up providing a CO₂ refrigerant system to European customers and an HFC-134a system to customers in other parts of the world.

Even before the EU decided to go with a ban on HFC-134a, the Environmental Protection Agency's Mobile Air Conditioning Climate Protection Partnership, involving government, industry, and environment groups, began to work on ways to reduce environmental damage from auto air conditioners. Sciance says the group is well on its way to identifying ways to reduce HFC-134a refrigerant emissions by at least 50% and indirect greenhouse gas emissions from the fuel used to power vehicle air conditioners by at least 30%. System changes might increase the cost of a car by about $40.

However, advances identified by the partnership may have only short-term benefits for HFC-134a systems because of the impetus created by the EU ban. Outside the EU, other forces are lining up against HFC-134a. In September 2004, California's Air Resources Board approved new regulations to reduce greenhouse gas emissions from new motor vehicles effective with the 2009 model year. However, automakers have sued the state in an effort to toss out the new regulation, which has been suspended pending the outcome of a trial in January 2007 at the U.S. District Court for the Eastern District of California.

The California regulations, which other states could adopt, apply to emissions of CO₂, methane, and nitrous oxide from car tail pipes, as well as CO₂ and HFC emissions from air conditioners. The complex regulations leave the method for reducing greenhouse gas emissions up to vehicle makers but are likely to force carmakers to consider substitutes for HFC-134a. When fully implemented in 2016, if they go into effect, the regulations will cost consumers an additional $1,064 for their air-conditioned cars.

Sciance says what he would like most of all from refrigerant makers is an alternative refrigerant as close as possible to HFC-134a with a global warming potential under 150. To this end, a group of automakers, refrigerant makers, and systems suppliers was formed at the end of June to evaluate new refrigerants with low global warming potential.

General Motors will support the research program, set up under the auspices of the Society of Automotive Engineers International, Sciance says. "I encourage chemical companies to move as promptly as they can to allow us to evaluate new products that meet EU regulations," he says. "They need to comply with our development lead times and get involved now to meet the 2011 deadlines."

Honeywell's Fluid H might fit the bill. It is a two-ingredient azeotrope that blends 1,1,1,2-tetrafluoropropene with trifluoromethyl iodide. Honeywell says its early tests indicate that Fluid H is nontoxic, does not deplete upper atmospheric ozone, and has a global warming potential under 10, which would allow it to easily meet new EU regulations. Its performance is also very close to that of HFC-134a, so systems using the new fluid would require only minor change.

Richard Preziotti, vice president and general manager of Honeywell fluorine products, says Honeywell can meet the EU's 2011 deadlines. The firm plans to have pilot-plant quantities of Fluid H available next year and commercial quantities available by 2011.

DuPont identified its best replacement candidate, dubbed DP-1, at the end of June. It has a global warming potential of 40. Early testing shows that, like Honeywell's refrigerant, DP-1 is nontoxic, does not deplete upper atmospheric ozone, and will work in HFC-134a systems with only minor modifications.

Mark S. Baunchalk, global business manager for fluoroproducts, declines to characterize DP-1's chemistry other than to say it is fluorine-based. He says he is confident that the new refrigerant could replace HFC-134a at lower cost than would a switch to CO₂.

Arkema plans to offer its candidate in the first quarter of 2007. Toxicity and flammability testing are still under way, the company says.

So changes are on the way, and HFC-134a is likely heading for a phaseout. But fluorine-based refrigerant makers will have to work fast if they expect to hold on to the auto refrigerants market.