Abstract

The growing demand for sustainable energy and effective waste management has intensified research into biomass valorization. This study explores the production of bio-briquettes from hydrochar obtained via hydrothermal liquefaction (HTL) of locust bean (Parkia biglobosa) pulp, using cassava starch as a biodegradable binder. Process optimization was conducted with the Taguchi method, considering binder concentration (10–30 %), particle size (300–600 µm), and compaction pressure (5–15 MPa), with moisture content as the primary response. Analysis of variance (ANOVA) identified binder concentration as the most significant factor (contribution ratio 91.64 %), followed by compaction pressure (6.11%) and particle size (1.74 %). Optimal conditions were 30 % binder, 300 µm particle size, and 15 MPa pressure, yielding briquettes with improved moisture content (1.09%), density (0.52 g/cm³), compressive strength (1.82 kN), calorific value (18.20 MJ/kg), and reduced ash content (8.71 %). Compared to control samples, the optimized briquettes exhibited higher ignition potential, durability, and combustion efficiency, meeting the requirements for household and small-scale industrial use. The findings demonstrate the potential of converting HTL residues of locust bean pulp into high-quality bio-briquettes, contributing to renewable energy generation, waste valorization, and sustainable rural energy solutions.