This paper investigated the effects of biomass bulk arrangements on their decomposition pathways. In
addition, the higher heating value and surface morphology of torrefied biomass received from two
different arrangements, hollow and compact bulk, was observed. The investigation was conducted at
torrefaction temperature of 250, 270, and 290 C and a residence time of 60 min. The evidence from
weight loss curves, SEM images, higher heating values, and numerical simulation confirmed that the
difference in bulk arrangements contributed to different decomposition pathways. The hollow bulk
arrangement contributed to a decomposition pathway which can be described by using the two-step
reaction in series model. The compact bulk arrangement resulted in an autocatalytic decomposition
pathway and a higher level of decomposition. This increasing level consequently led to a higher value of
the higher heating value compared to that of the hollow bulk arrangement.