Carbon Dioxide Extraction
This is a fairly new method of essential oil extraction, introduced at the beginning of the 1980s. It utilizes compressed carbon dioxide.
The technology calls for expensive and complicated equipment (several million dollars worth), which uses carbon dioxide at very high pressures and low temperatures.
With this method, more top notes, fewer terpenes, a higher proportion of esters and larger molecules are obtained.
The resultant oil is said to be more like the essential oil in the plant. Many terpenes in a distilled oil seem to form during the distillation process, which also breaks down some acetates (esters) in the plant material.
Carbon dioxide (CO2) extracted essential oils are pure, stable, colourless and have no residue of CO2 left in them. They should be excellent therapeutically, although this needs to be verified for each oil because of their different compositions.