Techno-enviro-economic analysis of second-generation bioethanol at plant-scale by different pre-treatments of biomass from palm oil waste

Abstract

This study evaluates three pathways: supercritical water treatment (SCW), CO2-water (scCO2-H2O), and catalytic hydrothermal hydrolysis (CHH) to produce second-generation bioethanol using palm tree fronds (PTF) as feedstock. The analysis focuses on technical performances using process simulation with Aspen Plus™, environmental evaluation by applying a Life Cycle Assessment (LCA) framework and an economic analysis using the levelized cost. The results of the technical performances reveal CHH as the best pathway for bioethanol production, with the highest ethanol yield at 273 L/tonne dry PTF and a substantial NER of 2.2, outperforming SCW and scCO2-H2O. From an environmental evaluation, CHH reveals lower carbon footprints of 61 g CO2 per MJ. Economically, CHH is competitive, with an ethanol production cost of 1.11 $/L, comparable to the enzymatic hydrolysis process. These findings provide the technical, environmental, and economic aspects of a promising route for lignocellulosic bioethanol production while suggesting pathways for further optimisation for future research.

Keywords

• Catalytic hydrothermal hydrolysis
• Palm tree frond
• Second-generation bioethanol
• Simulation
• Techno-enviro-economic assessment
• Thermochemical conversion