Magnesium cycle-based CO2 mineralization : Integration in Swiss Energy-from-Waste plants

An ex-situ, indirect aqueous CO2 mineralization pathway based on magnesium solvent cycling for precipitated calcium carbonate is studied for application in the Energy-from-Waste context in Switzerland. Necessary main equipment components, resources flows and energy requirements are determined for a mineralization plant capacity of 100 ktCO2/y. The options for input alkaline material are screened and a selection of scenarios are simulated using a library of models developed with the software OpenModelica. Assessed with the platform OSMOSE, the process integration to the municipal solid waste incineration plant and a range of heat utilities enables the determination of heat recovery opportunities and the assessment of the plant configurations options. In particular, it is found that the EfW boiler steam typically provides half of the heat requirements for the mineralization before design optimization. Three distinct scenarios for plant arrangement and calcium sourcing are defined, respectively assessing pure calcium salts, mined wollastonite ore and steel waste slags. The effective EfW plant decarbonization reaches 23.8% at best, but improvement on process efficiency and design may significantly increase this performance to achieve lower carbon intensities and EfW plant decarbonization potential of more than 64%. A profitability analysis of this decarbonization system shows that CO2 capture costs are relatively high, but that the PCC retail price might play an important role in offsetting the mineralization plant total annual expenditures.