Economic assessment and life cycle analysis of sugarcane bagasse valorization to bioethanol via one-pot deep eutectic solvent pretreatment

Abstract

The increasing global demand for sustainable fuels has heightened interest in lignocellulosic biomass conversion to ethanol. This study presents a technoeconomic and life cycle assessment (LCA) of novel one-pot ethanol production from sugarcane bagasse using microwave-assisted ternary deep eutectic solvent (DES) (choline chloride:ethylene glycol:nickel chloride hexahydrate in a molar ratio of 1:2:0.016) pretreatment. The process included microwave-assisted DES pretreatment, enzyme hydrolysis and fermentation in a one-pot multistep approach, followed by downstream separation and purification. A combination of process modeling from experimental data and Aspen Plus simulation for downstream separation was applied to the analysis of a plant with a capacity to produce 100 t of ethanol per day. The plant was assumed to be annexed to a sugar mill. OpenLCA 2.0 was used to construct the LCA model to analyze and quantify the environmental impact associated with producing 1 kg of ethanol as the functional unit. Further, to increase the robustness and reliability of the process, different scenarios and sensitivity analyses were studied. The base case considered was 10% solid loading at pretreatment and no recycling of pretreatment solvent, which resulted in a production cost of 1098 USD per t with a payback period of 5 years. The sensitivity analysis identified process improvement opportunities where increasing solid loading and DES loading could significantly reduce production cost by 30% and global warming potential, by 91%. Economic assessment revealed that increasing plant capacity would significantly reduce the production cost per t of ethanol, highlighting the benefits of scaleup in improving financial viability. These results underscore the value of integrated process optimization in enhancing bioethanol production while mitigating the associated environmental burden.