Potentials of torrefied pine sawdust as a renewable source of fuel for pyro-gasification : Nigerian and South African perspective

Abstract

The impacts of fossil energy on the climate and environment emphasize the need for alternative energy resources. The use of waste wood is one such method to potentially reduce fossil-based energy dependence. However, raw biomass fuel properties are generally poor and unpredictable, thus requiring pretreatment to maximize their energy potentials for an efficient conversion to syngas via pyrogasification. Two species of pine sawdust (PSD) wastes generated in abundance from large-scale timber industries in Nigeria and South Africa were investigated for improvements in their fuel properties after torrefaction. Samples were torrefied under optimum conditions of 300 °C and 45 min. Different analytical procedures show that the higher heating value (HHV), enhancement factor, energy density, and solid yield of the Nigerian PSD exceeded those of their South African counterpart by 2.38, 5.37, 3.49, and 11.15%, respectively. The HHV of the torrefied fuels increased by 57.29 and 37.9% for the Nigerian and South African PSDs, respectively, when compared to the raw fuels. Also investigated were improvements in their H/C and O/C ratios and thermal degradation at varied heating rates.