Waste Heat Recovery With Carbon Capture for Sustainable Aluminum Smelter Operation

Primary aluminum plants face challenges of low energy efficiency and high pollutant emissions, necessitating innovative solutions to meet sustainability goals. This study develops an integrated system combining a parallel two-stage Organic Rankine Cycle (PTORC) and a monoethanolamine (MEA)-based CO2 capture system (CCS). The PTORC recovers waste heat from exhaust gases and electrolytic cell sidewalls to support CO2 capture, while the MEA system removes carbon dioxide from flue gases. Modeling and optimization revealed that PTORC integration supplies 23.9% of the energy needed for CO2 capture at 1.7% CO2 concentration, reducing capture costs by 34% compared to a simple ORC. However, implementing this system increases aluminum production costs by 1.1%, offset by significant energy and emissions savings. The findings highlight the potential for waste heat recovery (WHR) and carbon capture to enhance aluminum plant sustainability, offering an economically viable pathway to improved efficiency and reduced environmental impact.