DuPont and Honeywell have entered a global joint development agreement to accelerate the development and commercialization of flourine-based, low global warming refrigerants for mobile air conditioning (MAC) systems in automobiles.
Today’s automotive air conditioners use hydrofluorocarbon (HFC)-134a—one of the basket of greenhouse gases monitored by the Kyoto Protocol. HFC-134a has a significantly larger global warming potential (GWP=1,300) than carbon dioxide (GWP=1). New regulations in Europe (the MAC Directive) phase out HFC 134a from 1 January 2011 onward for new vehicle models and from 1 January 2017 for all new vehicles. (Earlier post.)
DuPont and Honeywell will work together to identify, develop, test and qualify new low GWP refrigerants that could be cost-effective alternatives to other technologies currently being considered by the auto industry, which include CO2 as well as hydrocarbon (usually, propane and iso-butane) based systems.
Although HFC-134a in itself has a significantly higher GWP than CO2, automakers are also looking to understand the impact of the entire MAC system in the context of the vehicle and different operating conditions. The tool used for this is the Total Environmental Warming Impact (TEWI) analysis. TEWI takes into account the contributions to global warming of:
The overall efficiency of the air-conditioning system which directly affects fuel burned to power the system and thereby, the carbon dioxide from that related combustion;
The emission of CO2 from burning fuel to transport the (mass of the) air-conditioning system; and
The result of refrigerant being released to the atmosphere due to leakage, servicing and accidents.
A TEWI analysis by GM and Oak Ridge National Laboratory of HFC-134a and CO2 systems in different vehicles operating in different cities found that while CO2 systems can offer better TEWI performance in cooler regions, HFC-134a systems offered better TEWI performance in warmer regions. As an example of a contributing factor, the increase in compressor power consumption required in a CO2 MAC solution deteriorates fuel consumption.
DuPont and Honeywell are thus trying to develop a refrigerant with a lower GWP than 134a that is compatible with the conventional HFC-134a mobile air conditioning system technology and offers a more cost-effective industry transition versus CO2 technology.
We look forward to providing a near drop-in replacement that reduces the need for costly system redesign for the automotive industry. For the consumer, we will provide an environmentally friendlier, low-GWP solution without sacrificing comfort or reliability.—Terrence Hahn, vice president and general manager for Honeywell’s Fluorine Products business
In November 2006, DuPont Refrigerants demonstrated DP-1, a new, low GWP refrigerant. DP-1 is a two-component blend, the major component of which is a new non-flammable, fluorine-based compound. The minor component is a commercially available refrigerant. The refrigerant ran in an unmodified MAC system.
According to DuPont, DP-1 offers properties and performance similar to that of R134a while featuring zero ODP (Ozone Depletion Potential) and a very low GWP estimated at 40. (Earlier post.)
DuPont and Honeywell plan to share resources, investment and technology as part of the agreement. The companies will work closely with the automotive industry to qualify a low GWP alternative by mid-2007.
According to industry estimates, there are more than 400 million cars with air conditioning systems globally, with each system using between one to two pounds of refrigerant. Based on a test conducted by DuPont comparing mobile AC systems utilizing DuPont’s low GWP replacement refrigerant and CO2, widespread utilization of a fluorine-based refrigerant could lead to worldwide emissions reduction equivalent to 230 million gallons of fuel per year by 2017.