Comparisons of Influences of Mass Densities of Fuel Briquettes Produced from Eucalyptus, Olive Tree, Sorghum Stalk and Khat Waste Raw Materials On Burning Times

Abstract

Global energy demand is rising, causing overexploitation of fossil fuels and environmental challenges. Renewable sources, especially biomass briquettes from residues, offer sustainable alternatives. Ethiopia relies heavily on unsustainable biomass, leading to deforestation and degradation. The rising demand for household energy in Ethiopia has intensified reliance on fuelwood and charcoal, contributing to deforestation and environmental degradation. This study investigates the potential of four locally available biomass raw materials Eucalyptus, Olive tree, Sorghum stalk, and Khat waste—for briquette production. Raw materials (20 kg each) were chopped, air-dried, and carbonized under limited oxygen to produce char powder. The resulting char was mixed with 10% clay binder and water, molded into cylindrical briquettes, and oven-dried. Performance tests were conducted using the water boiling method, measuring density, burning temperature, and effective cooking times. Results revealed significant differences in density and effective cooking time among the briquette types. Khat and Olive tree briquettes exhibited higher densities (0.442 and 0.476 g/cm³) and sustained heating, maintaining water temperatures above 75°C for 101 and 73 minutes, respectively. Sorghum briquettes showed the highest peak temperature (96°C) but had short endurance (40 minutes), while Eucalyptus briquettes demonstrated the lowest density and inconsistent burning behavior, averaging only 31 minutes above 75°C. ANOVA confirmed significant differences (p < 0.05) among treatments, indicating that raw material type strongly influences briquette performance. The findings suggest that Khat waste and Olive tree residues are the most promising biomass feed stocks for producing efficient and sustainable fuel briquettes in Ethiopia, offering a renewable alternative to fuel wood and charcoal while addressing waste management and deforestation concerns.