Multi-objective optimization and thermo-economic assessment of a hybrid ORC system for power, freshwater, and hydrogen production using geothermal and solar thermal sources

• Increasing the turbine inlet temperature up to a certain level enhanced the net power. • There was an RO optimal feed pressure as the power consumption is minimized. • Increasing the electrical current density in the PEM lower the costs. • A temperature range of 167–190 °C could be selected as the turbine inlet temperature. • Increasing the pressure ratio in the ORC boosted the net power output of this cycle. The global challenges associated with energy sources and usage are becoming increasingly significant, resulting in widespread issues that affect countries worldwide. This situation compels nations to effectively manage energy resources and their associated pollution by harnessing waste energy and producing valuable outputs such as freshwater and hydrogen. In this work, two similar hybrid systems based on geothermal and solar thermal sources are studied and compared for the simultaneous production of electrical power, freshwater, and hydrogen, from the perspectives of energy, exergy, and economics. The proposed hybrid system utilizing geothermal thermal sources can effectively produce the required products, achieving an exergy efficiency of over 59%. It is capable of generating more than 40 MW of electrical power, over 70 kg/h, and 1000 m 3 /h of high-quality freshwater. In contrast, the solar system shows an exergy efficiency of less than 13% for the same products. Additionally, there is a significant difference in the life cycle costs of the two systems; the life cycle cost of the solar-based hybrid system is nearly four times higher than that of the geothermal-based system. A multi-objective optimization is also conducted for finding the conditions having the best energy efficiency, exergy efficiency and life cycle cost.