Chapter 4: Gasification of Bio-oil and Torrefied Biomass: An Overview

Current energy policies seek to decrease the dependence on fossil resources by supporting the production of fuels and chemicals, with a lower carbon footprint, from alternative feedstocks. Conversion of biomass to synthetic fuels and chemicals, using gasification followed by Fischer–Tropsch synthesis and refining, is of interest. Entrained flow gasification of coal and heavy oil is commercially practiced and can be used for the conversion of biomass feedstocks. Moreover, intermediates such as bio-oil and torrefied biomass can be used in entrained flow gasifiers with little modification. Bio-oils are produced from raw biomass via pyrolysis or hydrothermal liquefaction, while torrefied biomass is obtained via torrefaction. The use of these more homogeneous and energy-dense feedstocks can reduce biomass transport costs and allows decoupling of biomass availability from end-use application scale and location. This chapter discusses feedstocks, production processes and bio-oils and torrefied biomass properties, as well as their conversion to syngas via entrained flow gasification. Technical challenges and scale-up activities are presented. Concepts for decentralized bio-oil and torrefied biomass production, followed by centralized gasification, are compared to centralized raw biomass gasification. Required technological developments toward the implementation of syngas production from biomass feedstocks and for high-capacity Fischer–Tropsch processes are highlighted.