Techno‐economic assessment of CO2 capture from aluminum smelter emissions using PZ activated AMP solutions

Abstract

In order to reduce its greenhouse gas emissions without drastically changing currently‐used processes, the primary aluminum industry will need to consider capturing CO2 released in the electrolytic cells. In order to make the capture more economically attractive to the aluminum industry, the possibility of using a blended amine absorption solution which combines the advantages of two different amines (a fast reactivity from a cyclic polyamine, piperazine (PZ), and a high absorption capacity and low regeneration cost from a sterically‐hindered alkanolamine) is considered in this work. Specific to an aluminum plant, not only the costs and benefits of a CO2 capture facility are evaluated, but also the possibility and cost of coupling the capture process with a waste heat recovery strategy. A mixture of 0.08 g/g PZ and 0.32 g/g AMP appears to be the most appropriate, reducing the capital costs by 25 % and operating costs by 29 % compared to the use of MEA (monoethanolamine) solutions. The capture cost is evaluated to be 65.10 $/ton of CO2 avoided (without carbon tax). A thermal integration of the capture plant within the primary aluminum smelter could further reduce the cost to 57.57 $/ton of CO2 avoided, or equivalently, 69.56 $/ton of Al produced (without carbon tax).