Effect of Gelam Wood and Rice Husk Composition with Molding Pressure on the Combustion Performance of Biopellets

Abstract

This study investigates the effects of gelam wood (Melaleuca leucadendron) and rice husk composition in biopellet production, focusing on compaction pressures of 60, 80, and 100 kg/cm². Five biomass ratios (G100–RH0, G80–RH20, G60–RH40, G50–RH50, G0–RH100) were tested for moisture, ash, fixed carbon, volatile matter, calorific value, ignition time, burning rate, and combustion temperature. Results showed that moisture content ranged from 0.98% (G0–RH100, 60 kg/cm²) to 12.28% (G100–RH0, 80 kg/cm²), while ash content varied between 2.47% (G100–RH0, 60 kg/cm²) and 20.93% (G0–RH100, 80 kg/cm²). The highest calorific value reached 3968 cal/g (G100–RH0, 60–80 kg/cm²), though below the SNI 8675:2018 minimum of 4000 cal/g. Ignition times ranged from 52 s (G0–RH100, 60 kg/cm²) to 135 s (G100–RH0, 100 kg/cm²), with burning rates between 0.002072 g/s and 0.003778 g/s. Maximum combustion temperature varied from 249°C (G0–RH100, 60 kg/cm²) to 290°C (G100–RH0, 100 kg/cm²). These findings confirm that both composition and compaction pressure significantly influence pellet quality, where higher rice husk content enhances ignition and burning rate but reduces calorific value. In contrast, higher compaction pressure improves density and temperature but prolongs ignition. The study provides practical insights for producing energy-efficient biopellets from abundant local biomass in South Kalimantan.