Abstract
Ethiopia’s energy consumption predominantly depends on traditional biomass such as firewood, agro-residues, dung, and charcoal. The objectives of the study were to produce fuel briquette from Khat residue branches and leaves generated from Hawassa city as well as to evaluate the fuel quality of the briquettes produced, estimate their potential through determination of charcoal.
The Khat branch and leaves residue were carbonized in an oxygen-scarce environment separately by using carbonizing kiln at Alternative Energy Development and Promotion Directorate, Minister of Water, Irrigation, and Electricity. Then the carbonized resources were crushed to fine particles and mixed with a binder and transformed to briquettes by using a beehive briquette machine. Triplicate samples were taking for laboratory analysis and carried out by using American Society for Testing and Materials procedure. The laboratory analysis revealed that the fixed carbon content and calorific value of briquettes made from carbonized Khat branch, carbonized Khat leaves, a mixture of carbonized branch with carbonized leaves and a mixture of carbonized branch with un-carbonized leaves were 49.48 ± 2.45 %, 36.17 ± 1.33 %, 43.08 ± 0.58 %, 4.81 ± 1.42 % and 19,891 ± 748 kJ/kg, 13,837 ± 995 kJ/kg, 16,985 ± 793 kJ/kg, 1,988 ± 62 kJ/kg respectively, and through transformation of estimated total amount of wet Khat residues which were on average 4,549,595 kg/yr. from Khat branch, Khat leaves, a mixture of carbonized branch with carbonized leaves and a mixture of carbonized branch with un-carbonized leaves into briquette, annually the city could produce about 10, 6, 16 and 4 billion kilo Jules of energy which substitutes around 310, 198, 508, and 133 tonnes of charcoal or reduce approximately, 1,024, 652, 1,676 and 439 tonnes of carbon dioxide that release to the environment. In addition to this, the result indicated that fuel briquette produced from the carbonized Khat branch have higher quality in terms of lower values of moisture content, volatile matter, ash content but higher values of fixed carbon content, calorific value and bulk density than results obtained from other fuel briquettes produced, and also the fuel briquette produced from a mixture of carbonized branch and leaves have higher total energy, charcoal substitution and reduced carbon dioxide emission than other fuel briquette produced. Further analysis showed that the carbonized Khat branch and leaves briquettes were strong heat which got on average 23 min and 35 min to boil one latter of water and carbonized Khat branch and leaves fuel briquettes had total CO emissions of 728 (0.07%) ppm and 831 ppm (0.08%) respectively. It is concluded that fuel briquette produced from Khat residue could be used as an alternative source of energy, reduce alarming rate of deforestation and improve waste management.
Keywords: Binder; Carbonized; Charcoal; Deforestation; Fuel quality;
