Thermo-economic feasibility analysis of a novel integrated energy system based on solar hydrogen production

To address the instability of solar power generation and facilitate large-scale application, this study proposes a novel power-to-hydrogen technology. The novel design integrates transcritical CO2 power cycle-Kalina cycle cascade system and organic Rankine cycle in series to effectively utilize parabolic trough solar collector (PTSC) thermal energy for proton exchange membrane electrolysis cell-based hydrogen production while realizing CCHP. This study evaluates the feasibility of the proposed system using six heat transfer oils from thermo-economic perspectives and performs a multi-objective optimization for each, followed by a parameter analysis of the system. The system achieves the highest energy efficiency (39.71 %) and exergy efficiency (11.00 %) when Syltherm 800 is used, while Xceltherm LV offers the lowest cost rate (50.95 $/h). Using Therminol 59 results in the highest exergy destruction (10564 kW), with the PTSC subsystem exhibiting the greatest exergy destruction (66.2 %). Multi-objective optimization identifies Therminol 66 as the optimal working medium, achieving hydrogen production, exergy efficiency, and cost rate of 1.91 mol/s, 11.78 %, and 56.14 $/h, respectively, compared to the base case, the hydrogen production and exergy efficiency show significant improvements of 32.64 % and 10.09 %. Parameter analysis shows that when the power share of hydrogen production is 0, the system's performance reaches optimal.