A new integrated system for carbon capture and clean hydrogen production for sustainable societal utilization

• A new variation of KOH water splitting cycle is developed with carbon capture. • Integrated energy system is designed for multigeneration under different scenarios. • A thermodynamic assessment is carried out from energy and exergy aspects. • Economic feasibility is carried out and levelized cost of hydrogen is found. • The maximum energy and exergy efficiencies of the KOH cycle are 44.2 % and 67.66 %. Both hydrogen production and carbon dioxide removal are considered in this study as two of the critical pieces to achieve the ultimate sustainability target. This study proposes and investigates a new variation of potassium hydroxide thermochemical cycle in order to combine hydrogen production and carbon dioxide removal synergistically. An alkali metal redox thermochemical cycle is developed to utilize the potassium hydroxide uniquely through a nonequilibrium reaction. Also, the multigeneration options are explored by employing two-stage steam Rankine cycle, multi-effect distillation desalination, and Li-Br absorption chiller, which is integrated with potassium hydroxide thermochemical cycle for hydrogen production, carbon capture, power generation, water desalination, and cooling purposes. A comparative assessment under different scenarios is carried out. The energy and exergy efficiencies of the hydrogen production thermochemical cycle are found to be 44.2 % and 67.66 % when the hydrogen generation reaction is carried out at 180 °C and the separation reactor temperature is set at 400 °C. Among the multigeneration scenarios considered, a trigeneration option for producing hydrogen, power and freshwater provides the highest energy efficiency as 66.02 %.