Carbon utilization in natural gas-based hydrogen production via carbon dioxide electrolysis: Towards cost-competitive clean hydrogen

Abstract

Conventional blue hydrogen production still leads to direct carbon emissions, as well as significant energy consumption and costs for carbon dioxide (CO2) capture. CO2 electrolysis, which is one of the promising carbon utilization technologies, faces challenges beyond cell performance, including downstream separation. To address these issues, this study proposes a novel hydrogen production process integrated with CO2 electrolysis. Four integrated processes were developed based on two types of CO2 electrolysis in which cathode separation was either included or excluded. These integrated processes eliminate atmospheric carbon emissions from fossil-fuel-based hydrogen production without requiring a carbon capture unit; furthermore, the hydrogen yield increases. These processes were evaluated in terms of energy efficiency (EE), levelized cost of hydrogen (LCOH), and process carbon emission (PCE). Among the developed processes, the high temperature CO2 electrolysis without cathode separation (HT-CO2EL(w/oSep)) process exhibited the lowest LCOH and PCE. These findings demonstrate that proposed process effectively addresses the challenges associated with downstream separation and upstream heating inherent in standalone CO2 electrolysis systems. Compared with conventional blue hydrogen production, the HT-CO2EL(w/oSep) process achieved 22.2% improvement in EE, 12.0% reduction in LCOH, and 82.0% decrease in PCE. Sensitivity analysis shows that the proposed process remains economically viable compared to conventional blue and green hydrogen and is more adaptable to market fluctuations. The improvement in cell performance is expected to contribute to cost savings. Even accounting for methane leakage and carbon taxes, the process shows only a modest increase in total carbon emissions and LCOH.