Volkswagen va utiliser du CO2 comme frigorigène dans le système de conditionnement d'air de ses véhicules électriques (en anglais)

Le groupe Volkswagen développera un système de conditionnement d'air au CO2 pour une nouvelle gamme de véhicules électriques dont la production débutera fin 2019.

German car manufacturer Volkswagen announced to the journal Frankfurter Rundschau1 that its new electric vehicle "ID" series will be equipped with CO2 air conditioners. Since January 1st, 2011, the European mobile air conditioning (MAC) directive requires new vehicles to be equipped with an air conditioning system using a refrigerant with a Global Warming Potential (GWP) lower than 150. It involves the replacement of the traditionally used R134a. Most of car manufacturers now use R1234yf as a replacement.

Daimler was the first car manufacturer to use CO2 as a refrigerant in the air conditioning systems of some of its car models. Audi, a branch of Volkswagen, also began to equip its vehicles with CO2 air conditioning systems, but all in all only three models are equipped with such systems: Mercedes S and E-Class, and Audi A.

Volkswagen is the world's largest car maker, since it produces more than ten million cars every year. The production of a new vehicle equipped with a CO2 air conditioning system could give a boost for the use of this refrigerant in the rest of the car industry.

Maria Krautzberger, the Federal German Environmental Agency (UVA) President, recently reminded a controversy about the risks of pollution of water with trifluoroacetic acid (TFA), a substance coming from the degradation of R1234yf in the atmosphere. Those risks are in particular evoked in a report conducted by a group of environmental experts. A part of this report is based on a research commissioned by the Ministry of Environment, Agriculture, Nature and Consumer Protection of North Rhine-Westphalia. It asserts that R1234yf could be one of the factors contributing to this pollution.

The German Association of the Automotive Industry (VDA) nevertheless points out that the "former security issues" with R1234yf have been "clarified". Indeed, there are different points of view about the risks of R1234yf degradation into TFA. In an article published in 2016, Keith Solomon and Guus Velders made simulations and found that "total contribution to existing amounts of TFA in the oceans as a result of the continued use of HCFCs, HFCs, and hydrofluoroolefins (HFOs) up to 2050, is estimated to be a small fraction (<7.5%) of the approximately 0.2 µg acid equivalents/L estimated to be present at the start of the millennium".

More recently David Fleet et al. published a paper2 in the 1st IIR International Conference on the Application of HFO Refrigerants in which R1234yf was identified as the most widely used HFO refrigerant. They calculated the projected emissions of R1234yf between 2050 and 2500, with emissions of over 339,000 tonnes estimated for the 2100 plateau scenario. They performed a risk assessment on TFA which shows that toxicity risk of TFA to organism and human health appears to be low.

CO2 remains an alternative to high GWP refrigerants and to R1234yf, although it requires a little more complex technologies involving higher investments.

1J. WILLE. Schub für CO2-Klimaanlagen. Frankfurter Rundschau. 2018, August 11 edition. Available following this link.

2 D. FLEET, J. HANLON, K. OSBORNE. Study on environmental and health effects of HFO refrigerants. In: 1st IIR international conference on the application of HFO refrigerants. Available following this link.

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