Potential solution to the sustainable ethanol production from industrial tail gas: An integrated life cycle and techno-economic analysis

Utilising industrial tail gas for ethanol production is a viable pathway to significantly mitigate CO₂ emissions whilst simultaneously producing value-added fuels and chemicals, which has received great attention in recent years. While some technologies have been commercial deployed, new technological concepts continue to emerge in order to improve the life cycle and techno-economic performance. In this investigation, a novel ethanol production technology integrating tail gas-based ethanol (TG-ethanol) with electro-catalytic CO₂ reduction (ECR), called TGEE technology, was first proposed to address the energy and carbon efficiency issues associated with the state-of-the-art TG-ethanol technologies. The process was modularly modelled for to accommodate different ECR integration scenarios for three typical industrial tail gas streams (steel, iron alloy and calcium carbide). In addition, life cycle & techno-economic analysis based on Monte Carlo simulation were employed to evaluate the environmental and economic performance of the TGEE process. Results show that ethanol capacity can be increased by 1.3–2.9 times with carbon efficiency up to 36–82%. Life cycle carbon footprints of TGEE-ethanol were estimated to be 1.77–3.93 t CO₂eq/t ethanol, with a carbon reduction potential of 32–63% higher than the TG-ethanol. Minimum ethanol selling price is estimated to be 428–962 $/t ethanol, which is lower than the current ethanol market price (900–1080 $/t). Overall, the comprehensive analysis suggests that the TGEE process emerges as a more economically and environmentally benign next-generation technology for ethanol production from industrial tail gas.