Methane Synthesis from Air via Integrated Direct Air Capture and Electrolysis: A Techno-Economic Analysis

Air-to-methane pathways typically treat direct air capture (DAC) and water electrolysis as independent units for separate CO 2 and H 2 supply, leading to large energy and cost penalties. We introduce an integrated air methanation (IAM) concept that cascades electrochemical DAC into direct air electrolysis (DAE): by feeding the CO 2 -free, humid DAC effluent directly to the electrolyzer, the system enables alkaline DAE without air-CO 2 -induced carbonation that would otherwise occur in an air-fed electrolyzer. Furthermore, DAE-generated H 2 acts as a sweep gas to lower CO 2 partial pressure and increase DAC charge utilization. Our techno-economic analysis shows that this integration decreases the minimum specific energy from 2376.8 to 1078.3 kJ/mol CH 4 (−54.6%) compared to a decoupled configuration. The analysis further predicts a cost reduction from $3566.7 to $2715.0/ton CH 4 (−23.9%) and identifies electricity price, polarization losses, and stack capital cost as the dominant levers toward $1091.2/ton CH 4 .