Techno-economic assessment of pressure swing adsorption tail gas decarbonisation for blue hydrogen production

Abstract

Steam methane reforming (SMR) is a leading technology for hydrogen production. However, this technology is still carbon-intensive since, in current SMR units, the PSA tail gas containing H₂, CO, and CH₄ is burned at the reformer with air and exits the stack at a CO₂ purity of less than 5 %, which is not feasible to capture. In this paper, we aim to either harness the energy content of this gas to generate power in a solid oxide fuel cell (SOFC) or burn it via chemical looping combustion (CLC) or oxy-combustion process to produce off-gas with high CO₂ purity ready to storage. Therefore, an industrial-scale PSA with 72,000 Nm³/h feed capacity was modelled to obtain the tail gas flow rate and composition. Then, CLC, SOFC, and oxy-combustion were modelled to use tail gas. Finally, a techno-economic analysis was conducted to calculate each technology's levelised cost of hydrogen (LCOH). It was observed that CO₂ purity for CLC meets the criteria for storage (>95 %) without further purification. On the other hand, from the economic point of view, all three technologies show a promising performance with an LCOH of 1.9 €/kg.