The potential of molten metal oxide sorbents for carbon capture at high temperature: Conceptual design

Molten metal oxides represent a new opportunity for climate change mitigation through carbon capture. This study presents a conceptual coal fired power plant design that utilizes these liquid phase sorbents for high temperature CO2 capture coupled with the simultaneous removal of other acid gases. To effectively recover heat from the process both the absorber and desorber are located within the boiler and steam is used for near–isothermal regeneration of the sorbent. The potential thermodynamic opportunity was evaluated through process simulation, with results indicating molten sorbents could outperform the state-of-the-art amine-based systems for CO2 capture. An energy penalty as low as 6% points was projected for systems using molten sorbents, half that for the amine system. An initial economic evaluation confirmed the benefits of molten sorbents; for the optimized design, levelized cost of electricity increased 39% (25%–49%) relative to that for the power plant without carbon capture. The expected cost of CO2 avoided was $34/tonne ($18/tonne to $56/tonne) which is 38% (27%–50%) lower than that for the amine process and competitive with the social cost of CO2. Challenges were identified with future work proposed and justified by the opportunity to mitigate climate change at a lower cost than current systems allow.