Scalable biochar production from oil palm fronds and waste cooking oil: Techno-economic and policy-oriented evaluation for rural deployment

The increasing demand for sustainable biomass utilization and decentralized energy solutions has highlighted the need for low-cost biochar systems in rural areas. This study assesses the techno-economic feasibility of producing premium biochar from oil palm fronds (OPF) and waste cooking oil (WCO) through acid pretreatment and co-torrefaction in a 300-kg batch system, suitable for community-scale deployment. The process achieved a biochar yield of 60.95 %, an energy yield of 87.43 %, and a high heating value of 31.97 MJ/kg, classifying the product as premium-grade. Financial modelling included capital and operational costs, break-even point (BEP), net present value (NPV), and internal rate of return (IRR), supported by sensitivity analysis under varying market conditions. Under moderate scenarios, the system achieved an IRR exceeding 40 % and a payback period of less than two years. The analysis further explored scaling strategies, carbon offset potential, and enabling policy mechanisms relevant to palm oil-producing regions. Each batch was estimated to sequester 0.55 t-CO 2 -eq, aligning with circular bioeconomy goals and rural climate mitigation strategies. The model demonstrates that integrating biochemical pretreatment with co-torrefaction offers a viable and replicable solution for sustainable waste valorization, energy access, and carbon management in Southeast Asia. This study addresses key knowledge gaps by linking process optimization with economic and policy analysis, offering practical insights for cleaner production in decentralized settings. • Oil palm fronds were pretreated using acidic torrefaction water before co-torrefaction. • Co-torrefaction with waste oil improved biochar higher heating value to over 31 MJ/kg. • 300 kg batch system demonstrated strong techno-economic feasibility for rural use. • Feedstock cost and market price are key variables in the sensitivity analysis outcomes. • Findings offer policy and environmental insights for small-scale biomass valorization.