From process simulation to life cycle assessment: Generating life cycle inventory for the eco-design of essential oil extraction – A case study on Eucalyptus intertexta

Abstract

Essential oils from aromatic plants are increasingly sought after for applications in the food, cosmetic, and pharmaceutical sectors. This study investigates and compares two eco-friendly extraction processes for essential oils derived from Tunisian Eucalyptus leaves: supercritical fluid extraction and water distillation extraction. A comprehensive environmental impact assessment was conducted using Life Cycle Assessment with a functional unit of 1 kg of essential oil to enable direct comparison.

Process modeling using Aspen Plus® simulation software is used to generate Life Cycle Inventory of both processes. The Unifac-Dortmund model was employed to estimate liquid-phase activity coefficients, while the Hayden-O'Connell equation of state simulated vapor-phase behavior. The processes were scaled from laboratory and pilot levels to industrial production, achieving an annual capacity of 9 tons of essential oil.

Results show that supercritical fluid extraction, which uses CO₂ in a supercritical state, is significantly more energy-efficient and environmentally sustainable. Producing 1 kg of essential oil via supercritical fluid extraction required only 1.4 MJ of energy and resulted in 2.32 kg of CO₂-equivalent emissions, compared to water distillation extraction, which consumed 12.44 MJ of energy and resulted in 5.51 kg of CO₂-equivalent emissions. To further enhance the sustainability of supercritical fluid extraction, hydrosol—a by-product of distillation—was valorized. Additionally, waste by-products were combusted to generate electricity and heat, which were reintegrated into the process, improving overall energy efficiency.

An economic allocation approach was applied to distribute environmental impacts fairly across the co-products. This study highlights the environmental and energy performance of supercritical fluid extraction, emphasizing its potential for scaling as a sustainable alternative to conventional extraction methods.