Pyrolysis is the thermal decomposition of organic fuels (such as biomass resources) into volatile gases (such carbon monoxide, carbon dioxide, and water vapor), volatile liquids (such as bio-oil), and solids (char). Pyrolysis takes place under conditions with no oxygen or water. Currently, most of the interest in pyrolysis focuses on fast pyrolysis which involves rapid heating rates and high temperatures, and produces products similar to petroleum (bio-oil) and other fossil fuels currently in use.
The composition of the biomass feedstock (i.e., percent cellulose, hemicellulose, and lignin) is a key determinant of the yields and mix of products produced during biomass pyrolysis. Bio-oil is formed when gases and tars are cooled and condensed. It can be used as a heating oil, or to produce liquid transportation fuels and organic chemicals.
Pyrolysis is a precursor to gasification, and the same types of reactors used to produce syngas for electricity generation can also be used for pyrolysis.