Towards low-cost and sustainable biochar production based on empty fruit bunch: Effect of pelletization, microwave power, residence time, and mass on biochar quality for commercial approach

Abstract

Biochar produced from biomass based Empty Fruit Bunches (EFB) pyrolysis presents an alternative energy source. Biomass through the pelletization process will produce bio-pellets with higher density, while microwave pyrolysis achieves better energy efficiency and cost effectiveness. This two-step process will produce a product with a longer combustion duration and higher thermochemical conversion efficiency. This study aims to utilize EFB waste through a two-step process (pelletization and microwave pyrolysis) to produce biochar as an alternative renewable energy approaching commercial standards. EFB bio-pellets with a mass of 80, 100, and 120 g were pyrolyzed in a microwave pyrolysis reactor with the power of 450, 600, and 850 W, and in time variations of 20, 30, and 40 min. The results showed that 850 W power and 80 g mass were the optimal conditions to produce biochar with the highest heating value (26.73 MJ/kg), moisture content (0.48 %) volatile matter content (12.56 %), ash content (22.33 %), and fixed carbon (64.62 %). The SEM-EDX analysis indicated that the biochar product showed an increase in carbon (C) content up to 67.4 %. It is expected that combination of the pelletization process and microwave assisted pyrolysis could become a new alternative for producing biochar that could be commercialized. This research was carried out to address the problem of accumulating EFB in palm oil mills and generating renewable energy from waste.