Sustainable biodiesel production from waste cooking oil: Process design and techno-economic comparison of homogeneous and heterogeneous catalysis

This study aims to design and model four different semi-continuous process scenarios for biodiesel production, using virgin oil (VO) as a reference feedstock and waste cooking oil (WCO) collected from restaurants in Beirut. Both heterogeneous and homogeneous catalyst configurations were assessed by a thorough techno-economic analysis to identify the most efficient and cost-effective approach. A total collectable quantity of 22,740 kg/week of WCO was processed for the biodiesel production, representing a collection rate of 45 %. The project was developed with a 15 years lifetime and a target payback period (PBP) of 5 years. CaO and Amberlyst 46 were chosen as heterogeneous catalysts for transesterification and esterification, respectively, while KOH and H₂SO₄ were identified as reference homogeneous catalysts. Technical evaluations revealed that heterogeneous configurations were simpler, requiring fewer treatment steps compared to homogeneous ones, which necessitate catalyst neutralization and extensive purification of biodiesel and glycerol. The economic impact of the catalyst regeneration section was analyzed, particularly for the heterogeneous configurations examined without the CaO regeneration section. The economic feasibility of each setup was evaluated with focus on production capacity and how it impacts the PBP, using a 5-year payback as the reference. Among all configurations, the heterogeneous process without CaO regeneration required the lowest feedstock input of 5600 kg/day to achieve the 5-year payback target. However, as production capacity increased, the economic difference between configurations with and without catalyst regeneration decreased, indicating that catalyst regeneration becomes economically advantageous at larger scales. • Four hybrid-mode biodiesel processes were simulated using SuperPro Designer. • VO and Beirut-sourced WCO were assessed with homo- and heterogeneous catalysis. • Heterogeneous catalysis with WCO showed the best economic performance. • 5-year PBP achieved using 5600 kg/day WCO in non-regenerated CaO process. • Catalyst regeneration reduced the PBP gap by 95.6 % at higher feed rates.