Waste cooking oil biodiesel: production, characterisation and cost estimation

Waste cooking oil (WCO) is a promising renewable feedstock for biodiesel production that simultaneously addresses waste management and sustainable energy challenges. In this study, biodiesel was produced from WCO through alkali-catalyzed transesterification, and its physicochemical properties and production cost were evaluated for compression ignition engine applications. The transesterification process achieved a biodiesel yield of 92%–95% under optimised reaction conditions. The produced biodiesel exhibited a density of 870–890 kg/m³, kinematic viscosity of 4.2–5.0 mm²/s, flash point of 160°C–180°C, cetane number of 50–55, and calorific value of 37–39 MJ/kg, satisfying ASTM D6751 biodiesel specifications. The estimated production cost was ₹42–47 per litre, with an energy cost of ₹4.2–4.8 per kWh, demonstrating the economic potential of WCO biodiesel. A bibliometric analysis further highlighted the growing global interest in biodiesel research. The findings indicate that WCO biodiesel is a technically feasible and cost-effective renewable fuel that supports waste valorisation, circular economy principles, and sustainable energy development, making it a promising alternative to conventional diesel fuel.