Alternative refrigerants

With HFC-134a on the Kyoto Protocol list of global warming gases, and the European Union intending to eliminate it, experts at the SAE Automotive Alternative Refrigerants Symposium in July debated the future, with the goal of developing a more environmentally friendly alternative to keep vehicle occupants cool.

Another change of automotive air conditioning (A/C) refrigerant is on the horizon. HFC-134a is on the Kyoto Protocol list of global warming gases, and the European Union (EU) intends to eliminate it. The U.S. has not signed the Protocol, but many automotive systems are “world-engineered,” and the U.S. is only one-third of the global market.

The picture has changed since last year, when it seemed HFC-134a would soon be replaced (in Europe for openers) by carbon dioxide (CO₂), itself the standard of measure for global warming. CO₂, also known as dry ice, is a long-used refrigerant, a waste byproduct of many manufacturing processes (so it would not be “produced” for A/C), and certainly nonflammable (it is in many fire extinguishers). CO₂ actually is the greenhouse gas with the lowest global-warming potential-with a rating of just 1, compared with 1300 for HFC-134a and 3 for hydrocarbons (HCs). Flammable alternatives, such as HCs, were limited to underhood installation, with a heat exchanger and a secondary loop (containing liquid coolant) into the passenger cabin.