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Article Performance Assessment of a Solar-Geothermal Based Organic Rankine Cycle System Producing Green Hydrogen(Pergamon-Elsevier Science Ltd, 2026) Atak, Yagmur Nalbant; Nalbant Atak, YagmurThis study presents a comprehensive thermodynamic (energy and exergy) analysis of a solar-geothermal-based Organic Rankine Cycle (ORC) system integrated with a proton exchange membrane (PEM) electrolyzer for green hydrogen production. The system simultaneously harnesses the continuous heat of a geothermal source and the intermittent solar thermal input to ensure stable hydrogen generation. The effects of key operating parameters (solar radiation intensity, production well temperature, inlet temperature of the PTSC fluid, and ORC and PTSC working fluid types were investigated. The results reveal that higher solar radiation intensities significantly enhance both power generation and hydrogen yield, increasing the hydrogen production rate from 22.9 to 24.3 kg/h and the net electrical output from 4.17 to 4.41 MW. Similarly, increasing the geothermal well temperature from 400 K to 600 K significantly enhances hydrogen production, rising from 15.9 to 45.5 kg/h, and increases the net power output by approximately 185 %. However, the exergy efficiency decreases slightly from 0.26 to 0.17 due to increased irreversibilities at higher temperatures. The optimal working pair was determined to be R134a for the ORC and Therminol VP1 for the PTSC, achieving an electrical efficiency of 9.27 %, exergy efficiency of 25.13 %, and hydrogen production rate of 29.02 kg/h. In addition, the exergy analysis showed that the PTSC (similar to 35 %) and condenser (similar to 24.6 %) are the dominant sources of irreversibility. Finally, the Taguchi optimization identified the optimal configuration (Gb = 3.50 x 10(-4) MW/m(2), T-a = 500 K, T-11 = 600 K, and ORC fluid = R134a) yielding the highest overall efficiency and robust performance under variable operating conditions.Article Citation - WoS: 2Citation - Scopus: 2Thermoeconomic Analysis of an Integrated Membrane Reactor and Carbon Dioxide Capture System Producing Decarbonized Hydrogen(Pergamon-elsevier Science Ltd, 2025) Atak, Yagmur Nalbant; Ince, Alper Can; Colpan, C. Ozgur; Iulianelli, Adolfo; Serincan, Mustafa Fazil; Pasaogullari, UgurIn this study, a novel thermo-economic analysis on a membrane reactor adopted to generate hydrogen, coupled to a carbon-dioxide capture system, is proposed. Exergy destruction, fuel, and environmental as well as purchased equipment costs have been accounted to estimate the cost of hydrogen production in the aforementioned integrated plant. It has been found that the integration of the CO2 capture system with the membrane reactor is responsible for the reduction of the hydrogen production cost by 12 % due to the decrease in environmental penalty cost. In addition, the effects of operating parameters (steam-to-carbo ratio and biogas temperature) on the hydrogen production cost are investigated. Hence, this work demonstrates that the latter can be decreased by approximately 2 $/kgH2 when steam to carbon ratio increases from 1.5 to 4. The analyses reveal that steam-tocarbo ratio increases exergy destruction cost, affecting consequently also the hydrogen production cost. However, from a thermodynamic point of view, it enhances the hydrogen production in the membrane reactor, mutually lowering the hydrogen production cost. It has been also estimated that a decrease in the biogas inlet temperature from 450 to 400 degrees C can reduce the hydrogen production cost by 7 %. This study demonstrates that the fuel cost is a major economic parameter affecting commercialization of hydrogen production, while exergy destruction and environmental costs are also significant factors in determining the hydrogen production cost.
