In India, utilising low-temperature waste heat is crucial to improving energy efficiency. The regenerative organic Rankine cycle (ORC) process is a promising waste heat recovery technique in this study. Here, the thermodynamic behaviour of eight working fluids: Butane, Heptane, Hexane, Pentane, Cyclopentane, HexMDiSiloxn (MM), Benzene, and Toluene, was carefully examined. An elite Nondominated sorting genetic sorting algorithm (NSGA-II) was used in Multi-objective Optimization (MOO) to address the incongruent behaviour of thermodynamic performance (exergy efficiency) and economic performance (levelized energy cost, LEC). Every eight working fluids are the subject of MOO studies, and the resulting Pareto optimal fronts are created. Several advanced Pareto ranking techniques are taken into account to choose one ideal solution from the Pareto optimal front. These include Simple additive weighting (SAW), The technique for order of preference by similarity to deal Solution (TOPSIS), Grey relation analysis (GRA), and Multi-attributive border approximation area comparison (MABAC). The most economically advantageous working fluid is chosen using an explicit economic performance assessment index called the Static Investment Payback Period (SIPP). The results show that Pentane is the most economically advantageous working fluid with the shortest SIPP and a medium waste heat temperature range. The findings also imply that any working fluid can be used TOPSIS, SAW, GRA, and MABAC with entropy information considered in this study to recover low-temperature waste heat in the ORC.

Hydrogen is emerging as a key solution to meet the global transition toward clean and sustainable energy. In this context, the present work investigates hydrogen production by solar-assisted water electrolysis in the presence of dispersed metal oxide powders. Four identical electrolyzers were operated under natural solar irradiation (Condition 1: 11:00–18:00; Condition 2: 11:00–17:00) at a constant applied current of 1.5 A. Three metal oxides (ZnO, MgO, and CuO) were tested individually and then with 1 wt% Al₂O₃ to evaluate the effect of Al₂O₃ addition. As single oxides, MgO exhibited the highest cumulative improvement (+46.74% vs. the Witness cell), followed by CuO (+19.57%) and ZnO (+16.30%). After Al₂O₃ addition, higher normalized hydrogen production was observed under the investigated conditions: ZnO–Al₂O₃ showed the largest increase (+123.69% vs. ZnO alone, irradiance-normalized basis), followed by MgO–Al₂O₃ (+59.78%) and CuO–Al₂O₃ (+47.93%). These results indicate that the effect of Al₂O₃ addition on hydrogen productivity is strongly oxide-dependent, and identify ZnO–Al₂O₃ as the most promising system among those tested. Overall, the study provides new insights into the design of oxide-assisted electrolysis systems and supports their potential for further development of solar-driven hydrogen production.