The invention provides a method and system for extracting desired compounds from a plant or a plant based material featuring a) providing a plant or plant based material b) pumping CO2 gas from a CO2 storage vessel into an apparatus containing a CO2 circulation loop c) circulating CO2 through the plant or plant based material in the circulation loop d) extracting the desired compounds and e) discharging the CO2 gas from the CO2 circulation loop. The circulation loop may have a separator vessel and an extractor vessel, the desired compound may be a terpene, tetrahydrocannabinol (THC) or carbenoxolone (CBx), and the CO2 may be circulated as a supercritical CO2. The invention also provides a system for extracting a desired compound from a plant or a plant based material featuring a) an extractor vessel b) a separator vessel c) a liquid accumulator d) at least one hot water valve e) at least one cold water valve f) a gas pump g) a liquid pump h) at least one two-way valve i) a three-way valve and j) a CO2 storage vessel.
