ON TORREFACTION OF AGRO-INDUSTRIAL RESIDUES: FROM LOW-VALUE WASTES TO HIGH-QUALITY ENERGY CARRIERS

The torrefaction treatment, which is a technically feasible method for converting any lignocellulosic material into a high-energy density, hydrophobic, compactable, easily grindable, and biochemically stable coal-like solid, suitable for commercial and residential combustion and gasification applications, has been adopted to valorize wastes from agro-industrial activities. A review on the activities carried out by our research group will be reported. In particular, the role played by the main process variables (i.e., torrefaction temperature and reaction time) on the properties of the solid products (e.g., elemental composition, calorific value, ash content, etc.) and the process performances in terms of mass yield, energy yield and energy densification index has been evaluated. The effect of the reactor configuration (fixed bed vs. fluidized bed reactor) has also been investigated. Findings of this research work are useful to provide some guidelines for optimizing the process operating conditions yielding high quality energy carriers from low-value agro-industrial residues.