Federal regulators are offering incentives to automakers that adopt an environmentally benign coolant for vehicle air conditioners.
But the new coolant -- called hydrofluoroolefin, or HFO-1234yf -- is pricey stuff, so it may be a while before all automakers adopt it.
In February, the EPA approved its use, noting that HFO-1234yf has considerably less global warming potential than the coolant that it would replace.
The EPA standards are separate from, but similar to, corporate average fuel economy standards set by the National Highway Traffic Safety Administration. Under CAFE rules, automakers are required to improve their overall vehicle fuel economy by 40 percent by 2016.
If HFO-1234yf leaks from a vehicle's climate control system, it persists in the atmosphere for 11 days. By contrast, today's most commonly used coolant, R-134a, remains in the atmosphere for 13 years.
Automakers that switch to the new coolant will earn credits toward meeting the greenhouse gas standards set by the EPA.
Pressed by tough emissions rules, automakers in Europe already are moving to adopt HFO-1234yf. European regulations require automakers to switch to a more benign coolant than R-134a this year.
In the United States, General Motors said last year that it would switch coolants in all 2013 models.
Suppliers of climate control systems -- including Visteon Corp. of suburban Detroit and Denso Corp. of Kariya, Japan -- have begun adapting their hardware to accommodate the new coolant.
To improve efficiency, Visteon's new air conditioners have an additional heat exchanger built in, says Mike Munoz, the supplier's senior manager for climate advanced systems engineering. Visteon has made such hardware changes for an unnamed customer, Munoz says.
$108 per vehicle
The hardware redesign is not all that difficult. But Munoz notes that HFO-1234yf is expensive, costing $40 to $60 per pound. HFC-134a, another coolant that was widely used before R-134a, costs only $2 to $4 per pound.
Depending on the light vehicle size, an air conditioner might need about 1.3 pounds to 1.8 pounds of coolant, Munoz says. So the new stuff might cost up to $108 per vehicle.
Honeywell Specialty Materials produces the new coolant. David Diggs, Honeywell's global business director for refrigerants, says automakers can switch coolants without modifying their hardware.
The new refrigerant "is incredibly similar to 134a, so there isn't a lot of redesign," Diggs said.
To improve the efficiency of their air conditioners, some automakers were adding a heat exchanger even before the EPA approved HFO-1234yf.
"Some people will pay for the improved efficiency, and some won't," Diggs said. "That's the beauty of capitalism."