Valorization of durian and jengkol shell waste into high-performance green solid fuel through the effect of molasses-tar binder ratio on biobriquette properties

The declining availability of fossil energy in Indonesia has encouraged the development of more environmentally friendly alternative energy sources, including the conversion of biomass waste into solid fuels such as briquettes. However, biomass briquette production still faces challenges in improving product quality. This study aims to convert durian shells and jengkol shells into raw materials for biobriquette production using molasses and tar as binders. The charcoal composition ratios of durian shell to jengkol shell employed were 80:20, 70:30, 60:40, 50:50, and 40:60, each formulated with 25% molasses and tar binder. Briquette production included carbonization at 450 °C for 1 h, sieving to pass 100 mesh, mixing with 25% binder, pressing at 25 kg/cm2, and drying at 105 °C for 3 days. The resulting briquettes were analyzed based on proximate parameters and calorific value. The results showed that the lowest moisture content of 3.80% was achieved at the 40:60 composition with molasses, while the lowest ash content of 3.25% was obtained at the 50:50 composition with tar. Furthermore, the lowest volatile matter content of 1.07% and the highest fixed carbon content of 91.45% were found at the 40:60 composition with tar. The highest calorific value, 7010 cal/g, was recorded for the 80:20 composition with molasses, whereas the lowest, 5653 cal/g, occurred at the 40:60 composition with tar. All samples met the quality standards of Indonesian National Standard (SNI) No. 1/6235/2000. These findings indicate that the combination of durian shell and jengkol shell charcoal, particularly the 80:20 ratio using 25% molasses, produces high-quality biobriquettes with strong potential as an alternative biomass-based energy source.