Abstract

Background and Objectives: Waste from oil palm has the potential to be used as a sustainable energy source, despite its low fuel characteristics. To address this, the torrefaction technique was employed to convert the waste into a solid fuel with improved energy efficiency. Methodology: The study involved designing and constructing a continuous screw conveyor reactor for oil palm kernel shells (PKS) to enhance fuel properties at temperatures ranging from 200 to 300°C and residence times between 50 and 500 seconds. Main Results: The research found that the mass yield percentage was inversely related to the severity index of the torrefaction. Torrefied PKS had a higher fixed carbon content than untreated PKS, while moisture and volatile content decreased with increased torrefaction temperature and residence time. Optimal conditions were observed at 260°C and 500 seconds, resulting in the highest Energy-mass co-benefit index (EMCI) . This produced torrefied oil palm with low moisture and volatile content, higher fixed carbon, and increased heating value by 1.20 times compared to untreated PKS. Additionally, thermogravimetric analysis (TGA) revealed that torrefied PKS had lower moisture, volatile matter, hemicellulose, and cellulose content compared to untreated PKS. SEM analysis shows that the surface of torrefied PKS is smoother, attributed to the decomposition of hemicellulose and cellulose during the torrefaction process. The resulting torrefied product proves to be a more favorable biofuel option compared to untreated PKS. Conclusions: The continuous screw conveyor reactor demonstrated efficiency in torrefaction for improving biofuel characteristics in waste of oil palm biomass.