Cool technology options include CO2
and hydrocarbons. Though at the present there are no hydrocarbon based mobile air-conditioners sold on the OEM market for passenger cars, the use of hydrocarbons is technically feasible, as demonstrated by the large number of cars that have reportedly been converted from CFCs
to hydrocarbons. Refrigerants should only be used in equipment that has been designed for their use, to ensure efficiency and safe use.
HFO-1234yf is being widely adopted in passenger car air-conditioning as an alternative to HFC-134a. However, HFO-1234yf and other HFOs
are not considered Cool Technologies due to concerns over their long-term environmental impact. Some German car companies are using CO2
in a number of car series, based on concerns over the safety of HFO-1234yf. CO2
is expected to become a more attractive proposition as the electric car market grows.