Prospects of Sunlight Driven Air-to-Methanol Synthesis via CO2 Electrolysis
The race to save planet earth has led to significant advancement in technologies for harvesting renewable energy, carbon capture and conversion. Futures scenarios are being envisioned where CO2 is captured from air and converted to valuable fuels and chemicals, with methanol (MeOH) being the most coveted product. Here we assess two potential air-to-MeOH pathways that harvest solar power via concentrated photovoltaic (CPV) cells for direct air capture (DAC) of CO2 and subsequent conversion to MeOH by exploiting CO2 electrolysis. Specifically, we perform techno-economic and life-cycle analysis on single-step (direct CO2-to-MeOH electrolysis) and three-step (integration of H2O electrolysis, CO2-to-CO electrolysis, and hydrogenation reactor) air-to-MeOH routes. Our results indicate that in current scenario, the envisioned air-to-MeOH routes are not economically and environmentally compelling with high levelized costs of MeOH ~1180–1730 $/tonMeOH and CO2 emissions of ~2.29–2.69 /tonMeOH. Using sensitivity analysis, we reveal targets for CPV capital cost ($290/kW), DAC capital cost ($375/(ton-CO2/year)), and electricity emission intensity (<275 kg-CO2/MWh) which will make the three-step route commercially and environmentally viable as a near-term technology. In contrast, direct CO2-to-MeOH electrolysis will need drastic performance improvement to be economically competitive, with required current densities >300 mA/cm2, energy efficiency >45% and stack stability >2 years. We hope this study will garner the key stakeholders to advance discussions about the cost and potential of this envisioned air-to-fuel technology.