Environmental Sustainability Assessment of Biofuel Use in Internal Combustion Engines: An Integrated Study of Performance, Energy Efficiency, and Emissions

Abstract

This study aimed to evaluate the environmental sustainability of biofuel use in internal combustion engines through an integrated analysis of engine performance, energy efficiency, and environmental emissions. A descriptive-analytical approach based on a critical comparative review of scientific literature published between 2020 and 2025 was adopted. The evidence was organized into five interconnected dimensions: biofuel characteristics, engine performance, energy efficiency, environmental emissions, and environmental sustainability from a life-cycle perspective. The findings indicate that biofuels, particularly biodiesel and its blends, can under specific operating conditions maintain performance levels relatively close to those of conventional fuels while reducing carbon monoxide, unburned hydrocarbons, smoke, and particulate emissions. However, the evidence concerning nitrogen oxides, energy efficiency, and specific fuel consumption remains heterogeneous and is strongly influenced by fuel properties, blending ratio, engine configuration, and operating conditions. The analysis further demonstrates that reductions in tailpipe emissions alone are insufficient to establish environmental sustainability because environmental burdens may arise during feedstock production, processing, conversion, and transportation. The study therefore concludes that biofuel sustainability is conditional and multidimensional rather than absolute. A robust assessment should integrate fuel characteristics, combustion behavior, engine performance, energy efficiency, emissions, and life-cycle environmental impacts. The study recommends optimizing fuel blends and combustion-control strategies and integrating experimental engine assessment with life-cycle assessment to support more informed decisions regarding sustainable biofuel deployment.