Refrigerants For The Future: An Interview With Mack McFarland

evaporative car window cooler photo

Vintage Car Window-Mounted Evaporative Air Cooler. Image credit:ClassicAire, via

Refrigerant gases are back in the news - "HFC's" especially - now, because of their extended climate forcing potential. Remember the Montreal Protocol, that successful, 1989 global treaty to protect the earth's ozone layer? The Protocol still has an important role to play, in encouraging development of refrigerant gases that have reduced impacts on both the ozone layer and climate. TreeHugger interviewed Mack McFarland, Environmental Fellow with DuPont, Inc., and an active participant in both the Protocol and IPCC, to get his insights into what the refrigerant choices of the future will be, and how we'll get them. Stay cool, read on.Note: be sure to see Mack McFarland's bio-sketch or "CV," included at the end of this post.

Without further introduction, here's the interview.

John Laumer for TreeHugger: I still hear people refer to modern refrigerants as "CFCs". So, I assume many are not up on recent changes brought about by the Montreal Protocol. What are the most common HFCs in use today and where do they most affect people's daily lives?
Mack McFarland for DuPont: The most common HFC refrigerants in use today for new equipment are R-134a and two HFC blends R-410A and R-404A.

R-134a is used in household refrigerators, automotive air conditioners and some chillers for large buildings.

R-410A is used today in home air conditioners and will be used in new units produced for sale in the U.S. beginning on 1/1/2010 when the HCFC refrigerant R-22 can no longer be used.

R-404A is used today in commercial (e.g. supermarket) refrigeration systems and will be used in new systems beginning on 1/1/2010 when R-22 can no longer be used. In addition, there are a variety of options to retrofit existing equipment that use R-22 including DuPont's line of ISCEON® refrigerant blends.

TH: Related question: is the answer the same the world over? If different elsewhere, why?
MM: Yes, for the most part, the same HFC options are available around the world. Note: this questions was about HFCs.

TH: Do calculations of the climate forcing effect of HFCs include indirect emissions of C02 and/or chemical process emissions associated with the products' entire life cycle? If not, does that mean we are underestimating the seriousness of the future problem?
MM: Most analyses and most discussions of the HFC issue focus on their direct contribution to climate change only and do not include the indirect energy used to run the systems. In many cases, the climate contribution from CO2 emissions resulting from the energy used in these systems is significantly greater than the climate contribution of the HFC emissions associated with lifetime use of the systems. About 10% of global energy use, and hence, about 10% of global CO2 emissions are the result of running heat pumps, air conditioning and refrigeration systems. Hence, you are correct that it is very important to take energy use into account. In fact, HFCs are the refrigerant of choice in most applications because, on an equivalent safety and cost basis, they provide the best energy efficiency. Other life cycle components are minor compared to the direct HFC effect and the indirect energy component.

TH: I've heard that butane or propane can be used as refrigerants outside the USA. These petroleum gases have an extremely high heat transfer capacity and are very inexpensive. When will US consumers be able to purchase air conditioners and refrigeration equipment that are charged with something like that?
MM: Hydrocarbons are used in some countries as refrigerants in equipment that have small refrigerant charge sizes such as refrigerators. To my knowledge there are no commercially available air conditioners produced using hydrocarbons as refrigerants. I cannot speculate what might happen in the U.S. in the future.

TH: What is more urgent: reaching an international accord on phasing out HFC's or empowering consumers to make the choice on their own — by offering them designs that strike the right balance between climate and ozone protection?
MM: In my opinion, an international agreement to cap and reduce over time (not phase out) HFC quantities that can be used will be necessary to create the incentives for producers of refrigerants and manufacturers of equipment to make the very substantial research and development investments required to commercialize the next generation of energy efficient equipment using lower GWP refrigerants.

TH: What happened with the idea of vehicle air conditioners charged with C02 gas? Did it never pan out technically or was the cost too high?
MM: You should ask this question of the automotive OEM companies. What we can say is that there are issues that need to be addressed about the CO2 technology in terms of environmental performance, reliability, safety and practicality in service for the mass market. Safety issues due to high pressure and toxicity are not yet resolved. Reliability & warranty remains to be a concern. CO2 system's commercial viability in the mainstream small car segment in Europe is a major issue for any European auto OEMs.

DuPont has been working very closely with the automotive industry on the development of HFO-1234yf. Extensive testing has been completed involving environmental, safety and performance aspects of HFO-1234yf at DuPont and Honeywell facilities, independent and/or contracted third parties, individual auto OEMs, individual Tier suppliers and through various collaborative industry evaluations in the US, Europe, Japan and Asia. HFO-1234yf (jointly developed by DuPont and Honeywell) is now the preferred refrigerant solution to meet the EU MAC directive by the majority of automotive OEMs. These auto OEMs sell 69% of all autos sold in the EU and worldwide (see SAE Press Release for reference). Based on testing completed to date, DuPont believes HFO-1234yf is safe for use in the MAC application.

TH: Going forward, how can we encourage vehicle designers to take a carefully balanced look at environmental risk versus cost to manufacture? Is DuPont working with their customers to make this happen?
MM: DuPont Fluorochemicals is working with vehicle manufacturers around the world to provide a refrigerant (HFC-1234yf) that will allow them to meet safety, environmental and economic goals for vehicle air conditioning

A Summary CV for MACK MCFARLAND is included on the following page.

Refrigerants For The Future: An Interview With Mack McFarland
Refrigerant gases are back in the news - "HFC's" especially - now, because of their extended climate forcing potential. Remember the Montreal