Cascaded use of perennial industrial crop biomass: The effect of biomass type and pre-treatment method on pellet properties

Abstract

Lignocellulosic biomass should not be used as energy feedstock only. The extractable phytochemicals present in lignocellulosic biomass from perennial industrial crops (PIC) can be used in the pharmaceutical, cosmetic and chemical industries. A production residue, so-called “post-extraction biomass”, can be later used as energy feedstock. Therefore, the aim of this study was to assess the thermophysical and chemical properties of pellets produced from various types of post-extraction (after extraction with supercritical CO2 (SFE)) and non-extracted biomass (NE) obtained from five PIC species (willow, poplar, willowleaf sunflower and giant miscanthus). The highest lower heating value (17.40 MJ kg–1) was determined for willow Salix viminalis SFE pellets. The ash content was higher in pellets produced from green biomass willowleaf sunflower and giant miscanthus (mean 9.92% and 6.85% DM, respectively). Pellets from wood and a bark and wood mixture were included in one separate cluster. Another cluster was formed only for pellets from bark, with a separate cluster for pellets from green biomass. It was found with respect to the biomass pre-treatment that SFE pellet characteristic features included higher length, bulk density, mechanical durability, fixed carbon, cellulose, lignin, Cl contents (by 83%, 11%, 2%, 3.5%, 3.0%, 7.9%, 29.0% respectively) and lower moisture content, ash and volatile matter contents, higher heating value, lower heating value, C, H, N, S, soluble substance, hemicellulose contents compared with NE pellets.