Biomass feedstocks for renewable fuel production: a review of the impacts of feedstock and pretreatment on the yield and product distribution of fast pyrolysis bio-oils and vapors

Sources of Biomass Feedstock Variability and the Potential Impact on Biofuels Production

“…Densification also enables low-cost transportation, increases shelflife for outdoor storage, and improves feeding and handling performance. Dry and wet thermal treatments, such as torrefaction, mild hydrothermal carbonization, and steam explosion can also reduce hygroscopicity, increase grindability and shelf-life, and reduce volatiles and extractives content, including organic acids [20,104,105,114,116].…”

“…Lower ash can increase oil yields by 1-5 % for each 1 % of ash removed from native biomass [20,36]. Can cause reactor fouling, the change in ash content from wood (∼1 % ash) to straw (5-10 % ash) can change the deposition rate from 10 to 0.1 g deposit/kg fuel [14].…”

“…Extractives are made up of water-soluble components, such as non-structural sugars and proteins, and ethanol soluble components, such as chlorophyll and waxes. Volatiles from hemicellulose reduce fermentation efficiency in biochemical processes [39] and can increase the acidic nature of oil produced from thermochemical processes, which is associated with increase of viscosity during bio-oil storage [20]. Inorganic material, often referred to as ash, can be intrinsic to the biomass structure, such as calcium and potassium ions, or primarily anthropogenic, such as silica acquired during harvest.…”

“…Pyrolysis is typically performed at temperatures of 400-600°C [92] and often includes a catalyst [93]. Biomass pyrolysis processes have been extensively reviewed [19,20,[93][94][95][96][97][98].…”

“…Biomass should be dried to less than 10 % water content as additional water in the bio-oil affects stability, viscosity, pH, and other properties [19] including reduced heating rate and moisture in product [20].…”