Bio-oil is oil produced from vegetables and other plants and fats from animals or fish.

Bio-oil is mainly used for production of biodiesel but may also be used directly as fuel.

Examples of raw material for bio-oil:
Rape, soybeans, sunflower, coconut, jatropha or palm, as well as fats from animals or fish may be used as raw material.

Bio-oil may also be produced through thermal depolymerization, which is a process converting biomass or another carbon containing material into oil. This oil may be refined into various fuels similar to petro diesel or gasoline.

Thermal depolymerization may simplified be described as processes similar to the natural geological processes of forming fossil fuels but in a significantly shorter timeframe.

Under pressure and heat, long chain polymers of hydrogen, oxygen, and carbon decompose into short-chain petroleum hydrocarbons with a maximum length of around 18 carbons.

Conversion temperatures are typically 250 – 350 °C with a pressure range of 100-170 bar.

One version of this process that has being used to produce bio-oil is the “CWT” (Changing world technologies) process consisting of the following main elements:

In the method used by CWT, the water improves the heating process and contributes hydrogen to the reactions.

• Grinding of feedstock material
• Mixing feedstock material with water (if dry material is used)
• Feeding the raw material into a pressurised reaction chamber. Where heating at constant volume to 250 °C and 40 bar pressure is held in around 15 minutes.
• The pressure is rapidly released such that most of the water is boiled off. Leaving a mixture of of hydrocarbons and solid minerals.
• The mixture is feed into the second stage reactor at around 500 °C, breaking down the longer hydrocarbon chains.
• Finally the hydrocarbons are treathed by fractional destillation as in conventional refining.