LAUSR

Energy valorization of empty fruit bunches (EFB), via torrefaction, was investigated to stablish the best process conditions and the energy balance of an integrated plant. Differential scanning calorimetry was used, for the first time, as a new and more accurate method to determine the heat involved in the torrefaction process. This technique showed that the torrefaction of EFB is an endothermal process. A new response variable energy gain (EG) was introduced as an alternative to the customarily used variable energy yield (EY). EG was definitely a better response variable because it makes a compromise between a high mass yield and a high heating values of the solid product. On the contrary, EY has a very strong and direct (lineal) correlation with the mass yield that overshadows the effect of the heating value. Results show that torrefaction is a promising technology for the sustainable valorization of EFB because it solves the disposal problem and gives a solid and renewable biofuel that can replace coal. Besides, an important amount of electricity can be co-produced. Energy balances showed that energy self-sufficiency can be achieved by tuning the torrefaction conditions as to obtain a gaseous by-product that is used as fuel to provide the energy required in the drying and torrefaction stages. Processing 100 ton/day of EFB (dry basis), at 300 °C and 60 min, produces 37 ton/day of bio-coal (similar to sub-bituminous coal) and 0.36 MW electricity that can be exported because the process is energy self- sufficient.