CO2-to-methanol: Economic and environmental comparison of emerging and established technologies with dry reforming and methane pyrolysis

Abstract

This work compares 9 process routes that produce methanol from carbon dioxide using new and established thermochemical and electrochemical technologies. Net CO2 conversion is compared, and process efficiencies are benchmarked using side-by-side process models. New process routes using recently reported catalysts that enable methane pyrolysis (PY), and the dry reforming of methane (DMR) are modeled. Comparison is made with direct CO2 hydrogenation to methanol, the co-electrolysis of water and CO2 using solid oxide electrochemistry, and combinations of process technologies. Both electric heating and fuel switching to hydrogen are considered. Autothermal reforming of methane (ATR) is modeled as the conventional technology for reference. A new thermochemical approach in which CO2 reforming and methane pyrolysis reactions occur in separate reactors, with excess hydrogen produced and combusted for heat, (PY/DMR) was found to have the lowest levelized costs of CO2 mitigation varying from $50.4–53.9/t-CO2 using different electricity carbon intensities and levelized cost of methanol of $295.6/t. Methane pyrolysis offers the most flexible process solutions: it is nearly cost-competitive with reforming today ($295.6/t vs $277.3/t) using fuel switching and would emerge as the most economically viable process ($99.5/t) in future scenarios with very low electricity and natural gas costs and very high emissions penalties starting from 2030. Based on the emission factors from both electricity and natural gas across 195 countries around the world, 53 countries would result in net conversion of CO2 via pyrolysis today after heating, fugitive emissions, and energy use are taken into account.