Techno-economic study of CO2 capture for aluminum primary production for different electrolytic cell ventilation rates

• 4% CO2 concentration in the flue gas is the most economical and technical configuration for CO2 capture.
• The waste heat recovery allows to reduce by 58% the cost of capture.
• In the most favorable case, the capture cost is 100.15 $/ton Al (4.86% increase on the aluminum price).
• With thermal integration and incomes from tax, the capture represents 2.06% increase on its actual production cost.

As several other industries, primary aluminum production faces the challenge to reduce its greenhouse gas emissions, mainly composed of carbon dioxide (CO2). This work presents a techno-economic analysis of the implementation of a carbon capture plant specifically designed for a primary aluminum smelter, in order to investigate the feasibility to reduce CO2 emitted by electrolytic cells. It allows to verify if the capture using the traditional monoethanolamine (MEA) aqueous solutions can be economically attractive for the aluminum industry. The CO2 capture plant was sized and optimized taking into account typical aluminum production characteristics and several possible ways to capture CO2 were investigated. The effect of the increase of CO2 concentration in the flue gas (that could be achieved by reducing cell ventilation) and of plant thermal integration were taken into account in order to reduce the capture costs. It appears that 4 vol% CO2 concentration in the flue gas is the most economically and technically sound configuration. In addition, waste heat recovery allows to reduce by 58% the cost of capture if waste heat recovery is available in the primary aluminium smelter. Overall, the cost of capture could only represent 2.06% increase on its actual production cost (with carbon tax).