Assessment of the Influence of Temperature and Exothermic Effects During Torrefaction on the Properties of Agricultural Waste

Raw biomass presents challenges for energy use due to its high moisture content, low bulk density, and susceptibility to biological degradation, which hinder storage, transport, and utilization. An experimental setup was developed to investigate exothermic behavior during torrefaction of agricultural and food industry wastes. Exothermic reactions were observed between 190 °C and 450 °C, with more prominent effects in corn waste, sugarcane bagasse, and straw compared to sunflower husks, palm residues, and coffee skin. A series of tests performed on a torrefaction reactor with a core-type wall heating system showed that the heat generated by exothermic reactions makes it possible to reduce the torrefaction time by a factor of 1.5 (from 120 to 80 min) to obtain biochar of the required quality, with only a slight process temperature increase (15%, from 200 to 230 °C). These findings offer practical pathways for transforming waste into valuable biochar, fostering environmental resilience and socio-economic benefits in communities reliant on biomass resources.