Evaluation of fuel quality of invasive alien plants and tropical hardwoods as potential feedstock materials for pyro-gasification

Abstract

INTRODUCTION: Despite several studies carried out on the effects of the fuel properties of raw biomass on the final fuel properties of the biofuel after a thermochemical conversion, an identification and grading of various biomass types with respect to the level of their viability for pyro-gasification has not been established. OBJECTIVES: The primary objective of this study was to identify and rank eight waste wood feedstocks based on the suitability of their fuel properties for an efficient pyro-gasification using experimental data. METHODS: The wood samples were characterized using standard experimental procedures to determine their fuel properties. Five fuel evaluators relevant to the efficiency of a pyro-gasification process, were developed. The experimental data collated for each sample was used to carry out an evaluation exercise of the samples under each of the five fuel evaluators. Finally, the result of this exercise was used to rank the wood samples based on their suitability as feedstock for pyro-gasification. RESULTS: The hardwoods such as the Eucalyptus and African mesquite exhibited high fuel ratios, heating value and energy density which was as result of their higher lignin content. However, they exhibited minimal char reactivity. Conversely due to its higher holocellulose-to-lignin ratio, the Bugweed exhibited high char reactivity but lower fuel ratio, heating value and energy density. In comparison to the literature, the experimental results in this study were somewhat consistent with those of other biomass samples previously reported. The Fuel characterization exercise reveals that no wood sample can be considered completely efficient for pyro-gasification. The Jacaranda was however ranked lowest across the board. CONCLUSION: The variations in the hierarchy of the samples under the different fuel evaluators due to the disparities in their fuel properties paves way for further studies on the blending of waste wood samples with contrasting fuel properties in different mix ratios. This would enable the production of feedstock with the right balance in fuel properties suitable for an efficient pyro-gasification process. This study provides stakeholders with a framework for blending different lignocellulosic biomass species for thermochemical conversion.