Global warming and environmental pollution are accelerating due to the continued use of fossil fuels. To address these problems, biomass is being considered as an alternative and renewable energy source. In this study, the use of agricultural byproducts as a new bioenergy resource was investigated considering their conversion into a fuel via the torrefaction process. In particular, pepper stems (Capsicum annuum) were selected as a renewable agricultural byproduct for this energy conversion process. The longer residence time and the higher temperature, The larger amount of mass reduction and the higher heating value by torrefaction, which showed that there was a correlation between the heating value and mass reduction (R-2 = 0.9621). The reaction rate constants for the mass reduction model were then derived from the empirical Arrhenius equation. Thermogravimetric analysis was conducted to obtain frequency factors and activation energies of the biomass at different heating rates. The experimental results were in good agreement with simulated results (r(2) = 0.9639; root mean square error = 0.0363) when a heating rate of 7.5 degrees C/min was used, which also corresponded well with the rate of temperature increase inside the biomass. (C) 2019 Elsevier Ltd. All rights reserved.