Process design and energy requirements for the capture of carbon dioxide from air

A process to capture carbon dioxide from air to reduce its atmospheric concentration and to mitigate climate change is studied. It is based on the absorption of carbon dioxide in a sodium hydroxide solution, its precipitation as calcium carbonate, and its release as pure gas stream through oxy-fuel calcination. The process utilizes existing commercial technologies wherever possible, particularly in the case of the absorber, whose design is carried out in detail. The analysis allows deriving material and energy balances for the whole process and determining energy demands that can be used for a technical, economical, and environmental feasibility evaluation of the technology. In particular, it indicates that the real specific energy demand is larger than the heat released to emit the same amount of CO2 by the combustion of coal, and smaller than that of methane.