Pelletizing of lignocellulosic wastes as an environmentally friendly solution for the energy supply: insights on the properties of pellets from Brazilian biomasses

In the context of the circular bioeconomy and cleaner production, the incorporation of the by-products of plant biomass production in the bioenergy chain is fundamental. However, lignocellulosic wastes have properties that hinder their use for the production of biofuels. This study aims to evaluate how blends of lignocellulosic wastes improve the physical, chemical, and mechanical quality of pellets destined to the industrial sector, and to identify the challenges associated with the use of agroforestry biomass as raw material for pelletizing. Pellets were produced from blends of soybean wastes, sorghum wastes, pine needles, rice powder, Eucalyptus sawdust, and charcoal fines. Additionally, pure pellets composed of soybean wastes, sugarcane bagasse, and pine wood were evaluated. The effect of biomass type on the energy density, ash content, net heating value, and ultimate analysis was significant. The pellets produced with soybean wastes presented high contents of N (3.5-4.9%) and ashes (16.4-26.7%), besides low mechanical durability (≤ 96%), hindering its commercialization for industrial purposes. Pellets with sugarcane bagasse presented N (1.5%), S (0.03%), ashes (5.6%), mechanical durability (96.6%), and net heating value (15.1 MJ kg^-1), suitable for industrial energy use in accordance with ISO 17225-6. The high N and ash contents and the low mechanical durability are the greatest challenges for the energy use of pellets produced from Brazilian agroforestry wastes.