Integration of thermochemical water splitting with CO direct air capture.

Renewable production of fuels and chemicals from direct air capture (DAC) of CO is a highly desired goal. Here, we report the integration of the DAC of CO with the thermochemical splitting of water to produce CO, H, O, and electricity. The produced CO and H can be converted to value-added chemicals via existing technologies. The integrated process uses thermal solar energy as the only energy input and has the potential to provide the dual benefits of combating anthropogenic climate change while creating renewable chemicals. A sodium-manganese-carbonate (Mn-Na-CO) thermochemical water-splitting cycle that simultaneously drives renewable H production and DAC of CO is demonstrated. An integrated reactor is designed and fabricated to conduct all steps of the thermochemical water-splitting cycle that produces close to stoichiometric amounts (∼90%) of H and O (illustrated with 6 consecutive cycles). The ability of the cycle to capture 75% of the ∼400 ppm CO from air is demonstrated also. A technoeconomic analysis of the integrated process for the renewable production of H, O, and electricity, as well as DAC of CO shows that the proposed scheme of solar-driven H production from thermochemical water splitting coupled with CO DAC may be economically viable under certain circumstances.