Effectiveness and sustainability of millet husk briquette as an alternative source of thermal energy

The study aimed to investigate the effects of varying starch binder concentrations on the physical and thermal characteristics of carbonized and uncarbonized millet husk briquettes, and to compare their properties. This was achieved using a universal material testing machine to produce briquettes by varying the binder concentration to 25 – 40 % for both carbonized and uncarbonized samples. A proximate analysis results show an increase in moisture content (8.27 – 10.53 %), ash content (10.32 – 22.54 %), and volatile matter (40.03 – 54.03 %), but with a decrease in fixed carbon (41.35 and 12.98 %) for the uncarbonized and carbonized millet husk briquette. The physical properties show a range of compressed density (647.91 – 488.9 kg/m3), relaxed density of (666.67 – 548.5kg/m3), relaxation ratio (0.9719 – 0.9), and compaction ratio (2.91 – 2.76) for the carbonized and uncarbonized millet husk briquette. At the same time, the thermal properties show that the ignition time ranges from 3.6 to 14 seconds, with calorific values of (14.12 to 11.56 MJ/Kg) for the carbonized and uncarbonized millet husk briquette. However, based on the findings, carbonized briquettes have better characteristics and desired properties than uncarbonized briquettes for both domestic and industrial uses, based on the analyses. The findings also show that it is better to produce carbonized and uncarbonized briquettes at a binder concentration of 25 % considering the properties analyzed, where carbonized briquettes had better properties.