The extraction process also affects the oil yields.
1.Conventional distillation plant
Water distillation methods using traditional apparatus is time consuming with high-energy consumption and low yields.

2.Modified conventional distillation plant
A modified distillation plant  with  gas  fired stoves and agitation systems. Energy and mass transfers have been improved on the later model. However, the distillation system still requires on-going research and modification.

3.Solvent extraction unit
Solvent extraction can be used in combination with distillation. A hydrocarbon solvent is put in with the wood dust and dissolves the essential oil. The resulting solution is then filtered and put through a distillation process that concentrates the oil to produce a resin. The remaining substance  is  a  combination  of wax and essential oil called "concrete".

4.Supercritical fluid extraction unit
The supercritical fluid extraction method is non-flammable, non-toxic, and chemically stable and consumes less energy. It provides some advantages over the classical method, since supercritical carbon dioxide has low viscosity, high diffusivity, and good transport properties and gives  faster  extraction  and high yields.

The extraction process can be further enhanced by a pre-treatment process that is affected by many parameters including wood chip size, solid to liquid ratio, pH, soaking time and agitation speed. For the distillation process more study and research is still required. There are questions such as whether water or steam distillation is better. The impacts of pressure, temperature and distillation time should be further investigated.

For solvent extraction, the effects of the different types of solvents, pressure, temperature, extraction time and agitation speed should be studied.