Feasibility study on densification of rice straw for briquette production

Abstract

This study focused on the design, fabrication, and performance evaluation of rice-straw briquettes using locally available materials in Pallisa District, Uganda. The research aimed to develop a low cost, sustainable fuel alternative to charcoal and firewood by utilizing agricultural residues. The study followed an experimental research design where carbonized rice straw was combined with a composite binder made of cassava starch, clay, and molasses in ratios of 10%, 15%, And 20%. Briquettes Were produced using a hand-operated mold and compacted at forces of 0.16 kN, 0.22kN, and 0.31 kN. Mechanical and combustion properties including durability, compressive strength, bulk density, ignition time, burning rate, and calorific value were determined using standard procedures. Data were analyzed using mean ± standard deviation and graphical comparisons to assess performance differences among treatments. The economic analysis was conducted to determine production cost, market competitiveness, and potential charcoal substitution value based on the calorific value (14.74 MJ/kg) of the best-performing briquette batch. Results showed that increasing binder ratio and compaction force improved briquette strength, density, and energy value. The total production cost was estimated at UGX 500 per kg, while the selling price ranged from UGX 1,500–2,500 per kg, confirming profitability. Energy equivalence analysis indicated that 1 tonne of briquettes substitutes approximately 491 kg of charcoal, showing significant potential for reducing deforestation and improving rural energy access.