Cooling down the planet… with CO2

Using more carbon dioxide (CO2) in car air-conditioning systems could help combat climate change, according to a group of environmental and industry specialists.

Their call comes as carmakers face the challenge of replacing old fluorinated gases (f-gases) with more environmentally friendly alternative refrigerants.

Legislation banning the use of three f-gases in fire protection systems came into force this month, with several more products to be affected over the next four years. The automotive industry has until 2011 to begin a phase-out of their use in car air conditioning. The Alliance for CO2 Solutions, a pressure group whose members include Greenpeace and German and Swedish equipment manufacturers, says that the gas most commonly linked to global warming can in this case be used to combat climate change. CO2 can be used as a refrigerant.

Wolfgang Lohbeck of Greenpeace International said that technology to replace f-gases with naturally occurring CO2 was ready for the market.

He said that the cost of fitting CO2 technology to existing cars would be about €30 per vehicle. The EU car fleet contained 220 million vehicles in 2005, according to automotive industry figures.

HFC-134a, the f-gas widely used in car air conditioning, is estimated to have a global warming potential (GWP) between 1,000 and 4,000 times higher than CO2. Cars are currently the biggest market for f-gas manufacturers.

Cars imported to the EU from third countries will also have to meet the new EU f-gas requirements, increasing the pressure to find a globally acceptable new refrigerant.

Lohbeck dismissed efforts by chemicals companies to develop a new f-gas variant, which could be used in cars with no technological changes.

"In the short term this might be cheaper," he said, "but in the long run we do not know what will happen."

"History has until now showed that every member of this family of gases is unacceptable."

Another f-gas, CFC was banned by the international Montreal Protocol for all except medical uses in the 1990s, after being linked to global warming and the destruction of the ozone layer.

The Alliance for CO2 Solutions says that new technology could reduce car greenhouse gas emissions by 10%. It also hopes that using CO2 technology in cars would lead to its wider application in industrial refrigeration and vending machines.

But industry group the European Partnership for Energy and the Environment (EPEE), whose members include representatives of CEFIC, the European chemicals association, said that no single alternative to the banned f-gases would be suitable for all applications.

"CO2 refrigerants could make sense in a cold country," said Darcy Nicolle of the EPEE, "but because of their particular chemical properties, they would need a lot of energy to compress in the south of Europe."

Nicolle said that his group supported efforts by DuPont and Honeywell to develop a low-GWP f-gas for use in cars, which "would probably be more suitable for air conditioning and for warm countries".

"Technology does not stand still," said Nicolle. "There is no silver bullet solution for everything."

The European automotive sector is currently examining all the options and will publish a first opinion by the end of the year, according to Sigrid de Vries of ACEA, the European car manufacturers’ association.

De Vries said that harmonisation with non-EU car standards would always have to be taken into consideration in the end, but that it would have no effect at this stage.

Using more carbon dioxide (CO2) in car air-conditioning systems could help combat climate change, according to a group of environmental and industry specialists.

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