Technoeconomic and environmental analysis of bridging blue and green hydrogen production

• A combined blue-green hydrogen pathway is analysed through process simulation and technoeconomic analysis. • The combined system reduces cost and emissions compared to non-integrated methods. • Key issues of the combined system include oxygen supply reliability and scale mismatch between blue and green pathways. Production of hydrogen from hydrocarbons when coupled with carbon sequestration (blue hydrogen) is one of the cheapest forms, but residual CO 2 emissions persist. Green hydrogen production via electrolysis of water provides significantly less total CO 2 emissions but at an increased cost. One form of blue hydrogen production is autothermal reforming of natural gas, which collectively is an exothermic reaction. It required oxygen as a feed, the cost of the required air separation is however often prohibitive. There is however an opportunity for this oxygen to be provided as a byproduct of electrolysis. Hence, we explore the combined, integrated production of green and blue (via autothermal reforming) hydrogen. The technoeconomic and environmental evaluation yielded an overall LCOH of $4.68/kg for the combined process and a cradle-to-gate emissions intensity of 3.39 kg-CO 2 e/kg-H 2 . For hydrogen facilities transitioning to electrolytic production, this hybrid process results in reduced cost and emissions relative to non-integrated hydrogen production, but of course is operationally more complex: oxygen supply reliability and scale mismatch between electrolysis (small scale) and autothermal reforming (large scale) pose key technical barriers.