Study of ecological charcoal production from agricultural waste

Abstract

Wood fuel is undoubtedly the main source of energy for cooking in sub-Saharan Africa as it represents more than three quarter of household energy consumption. The exploitation of wood for fuel purposes contributes to forest degradation. It is becoming urgent to diversify domestic energy sources. Substituting other forms of energy with traditional ones is extremely difficult due to low income of the population and culinary habits. In this context, ecological charcoal seems to be an attractive alternative to wood energy. Agricultural waste was collected, dried to a moisture content of less than 10%. Waste was pyrolysed and the resulting carbonaceous material mixed with a binder and extruded to form briquettes. Three binders were tested: starch, clay and arabic gum. The pyrolysis of biomass generated three by-products: a solid (biochar), liquid and gaseous product. This process took 3 hours 45 minutes to convert 1tonne of waste into 390 kg of biochar and 133 liters of pyrolyser oil. After testing, biochar/binder ratios of 27/1.1, 27/2.7 and 27/2.1 for starch, gum arabic and clay, respectively, at a compaction pressure of 7.8 bar were validated.