In this study, it was aimed to produce solid fuel by applying the torrefaction process to agricultural wastes left in the field (usually left to decay) after harvest or post-cultivation period. An eggplant stalk left in the field as agricultural waste after the production period was used in the study. The torrefaction process was applied to the original plant parts cut in certain lengths and to the pellets prepared from the same plant. The torrefaction experiments were performed in a pyrex glass reactor placed inside a vertical cylindrical refractory chamber, through which resistance wires were passed. The torrefaction process was performed in an N2 atmosphere at the operation temperatures of 220, 260, and 300°C. The proximate and elemental analyses of the solid product were performed. Besides, the energy yield was determined by measuring the higher heating values (HHV) of the original sample and solid product. Depending on the torrefaction temperature, a decrease in the solid product yield and an increase in the yields of liquid and gas products were determined. While the volatile matter content of the solid product decreased, it was found that the rate of fixed carbon increased. It was also determined that the elemental carbon ratio increased and the oxygen ratio decreased as a result of the torrefaction process. It was detected that the higher heating value of the biomass increased with rising torrefaction temperature, and 65.58% of the energy contained was maintained under severe (300°C) torrefaction conditions.
