Integration of thermochemical water splitting with CO2 direct air capture

Renewable production of fuels and chemicals from direct air capture (DAC) of CO2 is a highly desired goal. Here, we report the integration of the DAC of CO2 with the thermochemical splitting of water to produce CO2, H-2, O-2, and electricity. The produced CO2 and H-2 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-CO2) thermochemical water-splitting cycle that simultaneously drives renewable H-2 production and DAC of CO2 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 (similar to 90%) of H-2 and O-2 (illustrated with 6 consecutive cycles). The ability of the cycle to capture 75% of the similar to 400 ppm CO2 from air is demonstrated also. A technoeconomic analysis of the integrated process for the renewable production of H-2, O-2, and electricity, as well as DAC of CO2 shows that the proposed scheme of solar-driven H-2 production from thermochemical water splitting coupled with CO2 DAC may be economically viable under certain circumstances.