Assessment of sawdust briquettesas valuable biomass fuel-energy productsin relation to their solid woods from ten plants of different densities

Abstract

Forests are enormous energy stores for fuel. Global resource base and supply are currently diminishing due to rapid population growth. Their management involves schemes, which provide accessible alternatives and sustainable energy sources for posterity, while meeting today's needs.Option involves densification of loose and granular wood and agricultural residues into compact and easily transportable fuel (i.e., briquette). This work compared the inter-specific calorific value (CV) variation of binder-less briquettes using sawdust from ten hardwoods and theircorresponding solid woods. The shavings were pressed at 300 oC and a load of 98 KN (i.e., 10 tonnes) in a Piston presser. Briquettes (0.7g) and corresponding solid woods (0.7g) were combusted ina bomb calorimeter. CV was directly proportional to wood density. High-density timbers (Miliciaexcelsa, Mansoniaaltissima, Antiaristoxicaria and Tectonagrandis) pressed best with greater briquette CVs (i.e.,21.66-28.53 MJ/Kg) than their corresponding solid woods (i.e., 17.29-25.93MJ/Kg). However, solid woods of the lowdensity timbers(Triplochitonscleroxylonand Ceibapentandra)produced slightly greater CVs (17.96-22.46 MJ/Kg) than their briquettes (12.10-19.89 MJ/Kg). The non-timber species (Jatrophacurcas, Moringaoleifera and Bambusa vulgaris) generated lessCVs but greater for thebriquettes (17.96-19.02 MJ/Kg) than theirrelated solid woods (21.66-24.20 MJ/Kg). Thus, the voluminous hardwood sawdust produced annually as residues abounds in much potential energy and could be briquetted and utilized as bio-energy to generate heat for domestic and industrial applications and rid the atmosphere of the health-threatening pollutant.