Energy Efficiency Evaluation from the Combustion of Selected Briquettes-Derived Agro-waste with Paper and Starch Binders

Abstract

A lot of agricultural residues and wastes generated in the country are improperly utilized and poorly managed. The bulk is left to decompose or blazed, resulting in environmental pollution and degradation. Studies have shown that briquetting provides a means of managing this waste as fuels however, energy efficiency of this process has not been investigated extensively. This study investigated the energy efficiency associated with combustion of selected briquettes-derived agro-waste. An experimental design was adopted that involved comparing the energy efficiency from the combustion of biomass briquettes of sawdust (SD) from different trees, rice husk (RH), coconut shell (CS) and corncob (CC) with paper (p) and starch (s) binders with wood (control). Energy parameters which include calorific value (CV), bulk density (BD), and energy density (ED) were measured. Energy efficiency parameters such as water boiling time (WBT), Mass of biomass used (MB), Burning Time (BT), Burning rate (BR) and Recoverable energy (RE) from the combustion of 0.5kg mass of each of the briquette treatments in comparison with the wood was obtained. The energy parameters of the biomass briquettes ranged 12.3 – 19.6 kJ/g, 0.27 – 0.75 g/cm3 and 3.9 – 13 KJ/cm3 for CV, BD and ED respectively. The ranges of the thermal properties based on the water boiling test carried out included water boiling time, mass of biomass used and burning time were 7.75 – 62.5 min, 150 – 390 g and 53.5 – 143 min respectively. Although sawdust briquettes took least time to boil water, coconut briquettes burned efficiently in terms of material conservation and duration of burning. Therefore coconut and sawdust briquettes are both viable alternative fuel sources to firewood.