1. Processing natural products

CO ₂ is considered the "green" solvent par excellence, non-flammable, non-toxic (apart from the risk of asphyxiation at high concentrations), widely available worldwide at low prices (around €0.15 to €0.20/kg in Europe) and high purity. As a non-polar solvent, it has relatively limited solvent power with respect to low- or non-polar compounds (hydrocarbons, lipids, aromas, etc.) compared with conventional non-polar liquid solvents, but much higher selectivity, enabling highly efficient fractionation of mixtures. More generally, supercritical solvents – with the exception of dimethyl ether, which is very rarely used – are therefore only a partial substitute for liquid solvents.