Exergoeconomic, carbon, and water footprint analyses and optimization of a new solar-driven multigeneration system based on supercritical CO₂ cycle and solid oxide steam electrolyzer using various phase change materials

This study presents an innovative multigeneration for power, cooling load, distilled water, and hydrogen production from solar energy. The proposed system is comprised of a supercritical carbon dioxide (sCO₂) ejector refrigeration cycle, a solar still desalination unit (SSDU), and a solid oxide steam electrolyzer (SOSE), integrated with parabolic dish collectors (PDCs) field. Exergoeconomic, carbon footprint (CF), and water footprint (WF) analyses are performed to assess the comprehensive performance of the system using seven inorganic and metal high-temperature PCMs, namely MgCl₂, NaCl, LiF-MgF₂, NaF-CaF₂-MgF₂, Zn-Cu-Mg, Cu-Si-Mg, and Cu-Si. It is found that Cu-Si delivers superior thermodynamic performance enhancement, and NaF-CaF₂-MgF₂ leads to the lowest economic, carbon, and water footprint performances among the desired PCMs. Moreover, multi-objective antlion optimization (MOALO) is conducted to ascertain and compare the maximum exergy efficiency and the minimum product cost, CO₂ emission, and water consumption rates of Cu-Si and NaF-CaF₂-MgF₂. Under optimal conditions, Cu-Si gives an exergy efficiency of 31.27% with hydrogen, net power, cooling capacity, and distilled water production of 44.56 kg/h, 1508 kW, 74.03 kW, and 15.48 kg/h, respectively, and NaF-CaF₂-MgF₂ yields the lowest cost, CO₂ emission, and water consumption rates of 73.55 $/h, 86.338 CO₂e/h, and 180.73 kg H₂O/h, respectively indicating 11.01%, 5.20% and 7.88% improvements with an 8.98% decrement in exergy efficiency compared with Cu-Si.