Variability and quality profiles of solid biofuels from standardized laboratory analyses

Solid biofuels, including forest residues, wood chips, wood pellets, briquettes, and sawdust, play a crucial role in sustainable energy production as renewable alternatives to fossil fuels. Understanding their physicochemical properties is essential for optimizing their utilization in energy recovery applications. This study presents a comprehensive characterization of these solid biofuels, focusing on parameters such as moisture content, ash content, low heating value, elemental composition, bulk density, mechanical durability, and fines content. The analysis was based on an extensive dataset collected by the Biomass Centre for Energy (CBE), from Portugal, and conducted following ISO standards. Forest residues show the largest variability: mean moisture of 36%, ranging from 3.6 to 70.1%, and a mean ash content of 11.9%, ranging from 0.6 to 31.4%, for example. This heterogeneity makes this fuel more suitable for energy recovery in large industrial furnace systems. Wood pellets, in turn, are markedly more uniform, with a mean moisture of 5.9%, ranging from 3.2 to 8.8%, and a mean ash content of 0.8%, ranging from 0.3 to 1.8%. Besides wood pellets, wood briquettes and wood chips also demonstrate superior fuel quality for commercial and residential applications due to their low moisture and ash content, high calorific values, and enhanced handling characteristics. The majority of these properties comply with ISO 17225-2, ISO 17225-3, and ISO 17225-4 standards.