(304f) Life Cycle Analysis of Catalyst-Free Intensified Supercritical Fluid Biodiesel Processes

The growing global population and industrialization, coupled with the urgent challenges of climate change, have intensified the search for renewable energy sources. Biodiesel has emerged as a promising alternative due to its renewable origin, biodegradability, non-toxic composition, and reduced environmental footprint. Its high flash point (423 K) further enhances safety during storage and transport. Among production methods, supercritical transesterification offers key advantages by enabling rapid conversion of triglycerides and simultaneous esterification of free fatty acids (FFAs) without a catalyst, under homogeneous supercritical conditions.

This study evaluates alternative process designs and their environmental impacts for biodiesel production from waste oil using supercritical fluids. Process simulations were performed in Aspen Plus, and environmental performance was assessed through Life Cycle Assessment (LCA). Two reactor configurations—a plug flow reactor (PFR) and a RadFrac rigorous distillation column—were examined, along with both supercritical methanol and ethanol routes. For each scenario, operating conditions including temperature, pressure, and oil-to-alcohol molar ratio were optimized.

This work presents one of the first comparative studies combining rigorous process simulation with LCA for these two alcohol-based supercritical processes. Environmental impacts were quantitatively assessed across categories such as climate change, ozone layer depletion, and human health. Results show that the supercritical ethanol route has a significantly lower environmental footprint, making it a greener and more sustainable option for future biodiesel production pathways.