A comprehensive energy, exergy, economic, and environmental (4E) assessment of a geothermal-driven polygeneration plant with energy storage using compressed hydrogen

The developed study conducts comprehensive energy, exergy, economic, and environmental investigates of a geothermal-assisted integrated plant producing green compressed hydrogen, power, heating, and freshwater. The present combined plant integrates a supercritical carbon dioxide-based Brayton cycle (sCO₂-BC), a transcritical carbon dioxide-based Rankine cycle (tCO₂-RC), a hydrogen production and storage unit, and a desalination process. The primary goal of this configuration is compressed hydrogen storage beyond green power, heating, and freshwater generation. In this paper, extensive thermo-economic and environmental impact study is executed parametrically to examine the plant's efficiency, economic cost, and the rate of emissions saved. Looking at base case results indicates that this plant's efficiencies are computed as energetically 25.84 % and 31.92 % exergetically. The net power, hydrogen, and freshwater capabilities of this integrated model are 1128kW, 0.001693 kgs⁻¹, and 1.28 kgs⁻¹ respectively. Likewise, the entire model cost rate and hydrogen generation cost rate are calculated as 149.1 $h⁻¹ and 1.479 $kg⁻¹. Moreover, regarding environmental impact, about 7174 tons of annual CO₂ emissions have been saved if the beneficial outputs obtained from the 200 ${}^{°}C$ geothermal sources are to be obtained by using natural gas (methane). The findings of this paper highlight the potential of hydrogen generation with renewable energy-based multigeneration plants in transit to net zero emission aims and can provide the basis for future innovative studies on this subject.