Biomass may require preprocessing before fed into a thermochemical conversion reactor. Drying, densification, pelletization and torrefaction are three most commonly used pre-preprocessing methods. Drying is needed to reduce biomass moisture content. Densification and pelletization increase the bulk density and flow characteristics; whereas torrefaction increases energy density and improves grindability. The degree and type of preprocessing depend on the thermochemical conversion process to be used. For example, pyrolysis may demand feedstock with relatively small particle size and moisture content compared to gasification process. However, since lignin is utilized in the thermochemical conversion processes, unlike biological conversion processes, removal or separation of lignin is not needed for the thermochemical conversion processes.