The Impacts of Producing Bio-Briquettes Made from Organic Waste as an Alternative Source of Fuel

Abstract

This work investigates the potential benefits of using bio-briquettes made from organic waste as an alternative source of fuel in sub-Saharan Africa. Over 80 million tons of organic waste are generated annually in the region. Our pilot case study in Zimbabwe processed mixed feedstocks sawdust, rice husks, groundnut shells, and bagasse using optimized parameters: drying at 105 ◦ C to <8% moisture, particle size reduction to <5 mm, slow pyrolysis at 400 ◦ C, 10% molasses binder, and 200 MPa compaction pressure. This process demonstrated an 85% mass conversion efficiency from raw feedstock to final bio-briquettes. The produced bio-briquettes exhibited calorific values of 20–25 MJ/kg, moisture content of <8%, an ash content of 2–4%, a bulk density of 600–800 kg/m 3 , and a sulfur content of <0.1%, as determined through standard proximate and ultimate analyses (ASTM standards). Techno-economic analysis revealed a production cost of US $45 per ton. Compared to traditional coal and charcoal, these bio-briquettes reduce sulfur emissions by over 60%, and ash waste by up to 80% and mitigate 2.5 tons of carbon dioxide equivalent (tCO 2 e) per ton of fuel displaced, while maintaining a near carbon-neutral lifecycle. This study confirms that valorizing organic waste into bio-briquettes provides a cleaner, economically viable alternative to fossil fuels, contributing to climate change mitigation, improved waste management, and sustainable development across the region.