Parametric assessment of solar and geothermal standalone hybrid system for power, green hydrogen, and freshwater production

A parametric feasibility study of a geothermal-PV hybrid system integrated with humidification–dehumidification (HDH) desalination, a PEM electrolyzer, and an organic Rankine cycle (ORC) is presented for simultaneous power, green hydrogen, and freshwater production. A mathematical model is developed and simulated in MATLAB. The parametric analysis shows that the mass flow rate and temperature of the geothermal fluid have the biggest influence on the overall system performance, which rises with their increase. The system delivers 10 kWh/h ORC power, ∼5.6 kWh/h PV power, 0.2 kg/h hydrogen, and 10.61 kg/h freshwater, with ORC and PEM efficiencies of 13.0 % and 63.7 %, respectively, and an overall system efficiency of 29.1 %. The HDH achieves a maximum GOR of 0.8. Average costs are estimated at $0.055/kWh for electricity, $4.75/kg for hydrogen, and $0.004/L for water, with CO2 emission reduction of 4.99 kg/h. Lifecycle financial analysis shows that increasing PV capacity from 0 to 20 kW (with ORC fixed at 10 kW) more than doubles NPV, raises IRR above 85 %, and shortens payback to 1.2 years, whereas increasing ORC capacity from 10 kW to 20 kW (with PV fixed at 10 kW) nearly doubles NPV and lifts IRR to 55 % with a slightly longer payback. Both approaches confirm robust economic viability compared to diesel generation.