Bio-oil. (Source: © nevodka.com / stock.adobe.com)

A liquid product of accelerated pyrolysis of biomass, containing a mixture of different components, such as furfural, phenols, or aldehydes, which can be used to produce alternative biofuels. Accelerated pyrolysis is a process in which biomass is heated rapidly in the absence of oxygen. The resulting bio-oil is a black, tarry substance remotely similar to petroleum. It is easier to store and transport than the original biomass and has a higher heating capacity due to the concentration. Because it contains high levels of oxygen, it is unstable and corrosive, and therefore unsuitable as car fuel. Once the oxygen and other unsuitable impurities have been removed, it can be used as a biofuel. The process is called upgrading.