Process analyses on sorption-enhanced electrified steam methane reforming for near-zero emission hydrogen production with CO2 capture by calcium looping thermochemical reaction

The predominant hydrogen production method is steam methane reforming, which generates substantial CO2 emissions from both the reforming reaction and the combustion required to drive the process. Sorption-enhanced steam methane reforming (SESMR) enables the in-situ CO2 removal during the reforming reaction, enhancing hydrogen yield. Replacing combustion with renewable electricity for reforming reaction can eliminate combustion-related emissions and flue gas heat loss. However, the intrinsic randomness, intermittency, and instability of renewable electricity present significant challenges to maintaining continuous and stable operation. This study introduces a process that innovatively leverages the mass and energy flow matching characteristics of the calcium looping with renewable electricity driving calcination, thermochemical energy storage, and sorption-enhanced steam methane reforming, thereby establishing the sorption-enhanced electrified steam methane reforming (SEESMR) process. The SEESMR exploits the dual functions of sorbent as both an energy carrier and a CO2 carrier. Renewable electricity facilitates calcination in the regenerator, storing energy in the form of chemical energy and sensible heat. This stored energy is subsequently utilized in the reformer during CO2 adsorption, providing the requisite energy to drive methane reforming and produce hydrogen. First and second law analyses indicate that SEESMR demonstrates a 7.90 percentage point improvement in thermal efficiency compared to SESMR through the substitution of combustion heating with electric heating and a high-efficiency heat recovery. Additionally, this modification reduces exergy losses by up to 53.2 % through elimination of combustion in SESMR. Furthermore, SEESMR enables continuous hydrogen production from renewable electricity, achieves a 35 % cost reduction within the current fuel pricing framework in China compared to direct electric heating methane reforming. This study may provide a stable, efficient and economical approach to zero carbon hydrogen production and large-scale renewable energy accommodation.