Status of Biochar and briquette technologies in Ethiopia: A review of production systems, efficiency and utilization

• Biochar adoption in Ethiopia is limited by technological fragmentation and gaps. • Continuous reactors show 20% higher efficiency than traditional batch kilns. • Batch reactors dominate 98% of Ethiopian production despite lower yields. • Biochar briquettes achieve energy densities of 18-28 MJ/kg using local binders. • Standardization of reactor design is critical for scaling national production. Ethiopia possesses vast biomass resources that remain underutilized for Biochar production due to technological gaps and efficiency constraints. This review systematically evaluates the current status of Biochar production and briquetting technologies in Ethiopia, analyzing reactor design parameters, conversion efficiencies, and performance indicators across documented systems. Analysis of 42 peer-reviewed studies and technical reports reveals that batch pyrolysis reactors dominate the sector, representing over 90% of documented installations, despite achieving 15-20% lower conversion efficiency than continuous systems. Biochar yields range from 25-45% depending on temperature (300-700°C) and feedstock type, while briquetting technologies produce fuel with energy density of 18-28 MJ/kg using local binders. Critical gaps identified include incomplete reporting of mass and energy balances (only 15% of studies provide complete data), lack of standardized characterization protocols, and limited validation of international kinetic models for indigenous feedstocks. The review concludes that scaling Ethiopia's Biochar sector requires standardized reactor designs, development of appropriate continuous systems adapted to local operational constraints, and policy frameworks supporting technology transfer and quality assurance.