On representative sampling and reliable chemical characterization in thermal biomass conversion studies

Careful consideration and proper execution of representative sampling and mass reduction procedures are critical for the validity and reliability of chemical analyses of highly heterogeneous biomass fuels. It is demonstrated how faulty sampling can result in apparent ash compositions that differ from the true compositions by factors of 2–3 for many major oxides. Analytical results based on non-representative samples are not representative for the specific fuel and processes being studied. Despite the general acceptance that accurate and representative compositions of biomass fuel and their derivatives are a critical prerequisite for understanding reactions and elemental fractionation during combustion and other thermal conversion processes, the biomass energy community appears largely to have ignored the critical issues surrounding representative sampling. This can have resulted in misleading or faulty conclusions and may have restricted our ability to perform reliable predictive modeling. We here point to effective yet simple sampling principles that should be implemented in future biomass fuel studies.