Exergetic and environmental life cycle assessments for waste cooking oil microemulsion biofuel in compression ignition engine

Abstract

Biofuels are considered as the alternative to petrofuels in Compression Ignition (CI) engines. However, investigations on combustion exergy, exergetic life cycle, and environmental impacts are imperative for understanding the sustainability of biofuel in engine applications. In the present study, the sustainability of Waste Cooking Oil (WCO) microemulsion biofuel in CI engines is validated by evaluating the life cycle performances, emission characteristics, and cogeneration potential. The life cycle assessment (LCA) analysis indicated that the environmental impact of fossil resource exploitation could be reduced up to 34% with WCO microemulsion biofuel–petrodiesel blends (WMBDs) in comparison to petrodiesel. Moreover, CO, CO2, and NOx emissions decreased for WMBDs at different load conditions. In addition, WMBDs exhibited higher cylinder pressure and the highest net heat release rate (NHRRmax) than petrodiesel. WMBDs showed the net system exergy output, relative shares of brake power, and exhaust exergy comparable to petrodiesel, justifying the cogeneration potential of the formulated WCO microemulsion blends. In addition, WMBDs exhibited higher utilization efficiency over petrodiesel in exergetic life cycle assessment analysis. Furthermore, the resource utilization efficiency and environmental sustainability could be increased up to 27.76% and 26.62%, respectively, with waste heat recovery (cogeneration) facility for WMBDs. CI engines (both with and without integrated cogeneration facility) fueled with WMBDs outperformed petrodiesel in terms of environmental sustainability.