Bio-oil

Pyrolysis oil, sometimes also known as biocrude or biooil, is a synthetic fuel under investigation as substitute for petroleum. It is extracted by biomass to liquid technology of destructive distillation from dried biomass in a reactor at temperature of about 500 °C with subsequent cooling. Pyrolytic oil (or bio-oil) is a kind of tar and normally contains too high levels of oxygen to be a hydrocarbon. Which results in non-volatility, corrosiveness, being immiscible with fossil fuels, thermal instability and a tendency to polymerize with exposure to air. As such it is distinctly different from similar petroleum products. The process of oxygen removal is also referred to as upgrading, which also applies to the removal of nitrogen from algal bio-oil.

There have been few standards efforts so far for pyrolysis oil; one of the few is from ASTM.

Pyrolysis is a well established technique for decomposition of organic material at elevated temperatures in the absence of oxygen into oil and other constituents. In second-generation biofuel applications—forest and agricultural residues, wood waste and energy crops can be used as feedstock.

When wood is heated above 270 °C it begins a process of decomposition called carbonization. If air is absent the final product, since there is no oxygen present to react with the wood, is charcoal. If air, which contains oxygen, is present, the wood will catch fire and burn when it reaches a temperature of about 400-500 °C and the fuel product is wood ash. If wood is heated away from air, first the moisture is driven off and until this is complete, the wood temperature remains at about 100-110 °C. When the wood is dry its temperature rises and at about 270 °C it begins to spontaneously decompose and, at the same time, heat is evolved. This is the well known exothermic reaction which takes place in charcoal burning. At this stage evolution of the by-products of wood carbonization starts. These substances are given off gradually as the temperature rises and at about 450 °C the evolution is complete.

...
Wikipedia