A geothermal multigeneration system integrating an ORC configuration with an open-feed heater for electricity/H₂/cooling production: Techno-economic optimization using a genetic algorithm

This research presents a novel geothermal-based multigeneration framework engineered to supply electric energy, hydrogen gas, and chilled water. The framework incorporates an organic Rankine cycle (ORC) with an open feed heater (OFH), a Kalina cycle (KC), an absorption refrigeration cycle (ARC), and a PEM electrolyzer (PEME). A comprehensive thermodynamic and economic evaluation is performed, followed by a multi-objective optimization using NSGA-II in MATLAB to maximize exergetic performance and minimize cost. Key parameters include geothermal fluid temperature, mass flow rate, ORC turbine inlet temperature, and evaporator pinch point temperature difference (PPTD). The ORC exhibits the highest exergy destruction (42 %), trailed by the KC (26 %) and PEME (19 %), while the ARC contributes the least (13 %). Elevating geothermal fluid temperature significantly enhances exergy efficiency and hydrogen output, although costs increase. Enhancing the mass flow rate from 5 kg/s to 18 kg/s substantially improves power generation and cooling capacity but diminishes efficiency and escalates equipment expenses. Increasing the evaporator PPTD reduces power output and hydrogen production yet increases chilled water generation and slightly lowers the overall cost rate. Under optimal conditions, the plant achieves the exergetic performance of 38.56 % and a cost rate of 17.11 $/h, highlighting the potential of this integrated approach to deliver sustainable, cost-effective solutions for electricity generation, refrigeration, and hydrogen production from geothermal resources.