Optimization of briquetting parameters and their effects on thermochemical fuel properties of biowaste briquettes

Ethiopia faces growing environmental and energy problems because of its expanding cities, increasing dependence on biomass fuels. This study evaluated briquettes made from sawdust, coffee husk, fruit waste, flower waste and vegetable residues through different particle sizes (0.3-1 mm, 2-4  mm, 5-7 mm) and compaction pressures (5  MPa, 10 MPa) using pulped paper as a binder. The evaluation of fuel properties included density measurements, moisture content, ash content, fixed carbon, volatile matter and calorific value assessments. The combination of small sawdust particles under 10  MPa pressure produced briquettes with the highest calorific value of 20.96 MJ/kg and strong mechanical strength. The combination of small coffee husk particles under 5 MPa pressure produced briquettes with 78.05 % volatile matter and 17.62 MJ/kg calorific value. The addition of binder materials improved combustion properties and decreased the amount of volume expansion. The waste volume reduction through briquetting reached 54.8 % which demonstrates its effectiveness as a waste reduction technique. However, this study did not include combustion emissions analysis, life cycle assessment (LCA), techno-economic evaluation (TEA), or pilot-scale field validation. Hence, the reported substitution and deforestation mitigation figures were theoretical and based solely on laboratory-scale calorific equivalence. As such, broader claims regarding environmental and energy system impacts should be considered preliminary and require further verification through real-world deployment and systems-level analysis.