A hybrid electro-thermochemical device for methane production from the air

Abstract

Coupling direct air capture (DAC) with methane (CH₄) production is a potential strategy for fuel production from the air. Here, we report a hybrid electro-thermochemical device for direct CH₄ production from air. The proposed device features the cogeneration of carbon dioxide (CO₂) and hydrogen (H₂) in a single compartment via a bipolar membrane electrodialysis module, avoiding a separate water electrolyzer, followed by a thermochemical methanation reaction to produce CH₄. H₂-induced disturbances lead to efficient CO₂ extraction without pumping requirement. The energy consumption and techno-economic analysis predict an energy reduction of 37.8% for DAC and a cost reduction of 36.6% compared with the decoupled route, respectively. Accordingly, CH₄ cost is reduced by 12.6%. Our proof-of-concept experiments show that the energy consumption for CO₂ release and H₂ production is 704.0 kJ mol⁻¹ and 967.4 kJ mol⁻¹, respectively with subsequent methanation achieving a 97.3% conversion of CO₂ and a CH₄ production energy of 5206.4 kJ mol⁻¹ showing a promising pathway for fuel processing from the air.