Integrated PSA Hydrogen Purification, Amine CO2 Capture, and Underground Storage: Mass–Energy Balance and Cost Analysis

Although technologies used in non-fossil methane and fossil resources to produce blue hydrogen are relatively mature, a system-integrated approach to reference system (RS)-based purification of H2, CO2 capture and storage, and UHS is relatively unexplored and requires research to fill gaps in the literature regarding balanced permutations and geological viability for net-zero requirements. This research proposes a system-integrated process for H2 production through a PSA-based purification technique coupled with amine-based CO2 capture and underground hydrogen storage (UHS). The intellectual novelty of the research is its first quantitative treatment of synergistic effects such as heat recovery and pressure-matching across units. Additionally, a site separation technique is applied, where H2 and CO2 reservoirs are selected based on the permeability of rock formations and fluids. On a research methodology front, a base case of a steam methane reforming process with the production of 99.99% pure H2 at a production rate of 5932 kg/h is modeled and simulated using Aspen Plus™ to create a balanced permutation of mass and energy across units. As per the CO2 capture requirements of this research, a capture of 90% of CO2 is accomplished from the production of 755 t/d CO2 within the model. The compressed CO2 is permanently stored at specifically identified rock strata separated from storage reservoirs of H2 to avoid empirically identified hazards of rock–fluid interaction at high temperatures and pressures. The lean amine cooling of CO2 to 60 °C and elimination of tail-gas recompression simultaneously provides 5.4 MWth of recovered heat. The integrated design achieves a net primary energy penalty of 18% of hydrogen’s LHV, down from ~25% in a standalone configuration. This corresponds to an energy saving of 8–12 MW, or approximately 15–18% of the primary energy demand. The research computes a production cost of H2 of 0.98 USD per kg of H2 within a production atmosphere of a commercialized WGS and non-fossil methane-based production of H2. Additionally, a sensitivity analysis of ±23% of the energy requirements of the reference system shows no marked sensitivity within a production atmosphere of a commercially available WGS process.