The global demand for renewable energy solutions has increased significant interest in utilizing waste biomass materials as a promising alternative to fossil fuels. In this study, briquettes were produced from carbonized agricultural wastes (coconut husk, corn cobs, and cowpea shells) using starch and clay as binders. Carbonization was performed by conventional heating at temperatures ranging from 300 to 500°C and residence times of 45-120 min. Agricultural residues and biochar were characterized by ultimate and proximate analyses. The characteristics of the briquette samples were assessed in terms of burning rate, compressive strength, shatter index, and calorific value. The factors - biochar type, binder type, and ratio - were used to evaluate the effects on the physiochemical properties of briquettes. Three different biochar-to-binder ratios were investigated: 70:30, 80:20, and 90:10. The results demonstrated that the briquettes exhibited a burning rate from 0.65 to 3.22 g/min, a time to boil water from 7.62 min to 23.56 min, a compressive strength from 11.38 to 39.66 N/mm2, a shatter index from 77.45 - 99.81 %, and calorific values from 14.71 to 24.02 MJ/kg. Notably, briquettes with a 70:30 ratio achieved the highest shatter index of 99.81% and compressive strength of 39.66 N/mm², while those with a 90:10 ratio recorded the highest burning rate of 3.33 g/min, the quickest time to boil water of 7.62 min, and the highest calorific value of 24.02 MJ/kg. This study contributes to the utilization of agricultural waste residues, accentuating their potential as alternative fuel sources for local energy applications.
Osei-Owusu et al. (Tue,) studied this question.