Simulation and multi-aspect investigation of a geothermal-based power, hydrogen, oxygen, and fresh water production integrated into a flue gas-driven combined power plant

Abstract

This paper introduces and evaluates a novel multi-generation structure that employs geothermal energy and utilizes waste heat from flue gas. This innovative structure includes a combined flash and binary geothermal system, a multi-effect desalination subsystem, a proton electrolyte membrane electrolyzer, a steam Rankine cycle, and a dual-pressure organic Rankine cycle. The proposed plant is evaluated from energy, exergy, economic, and environmental viewpoints. Moreover, a detailed parametric analysis is performed to study the effect of different parameters on the system performance. Results obtained demonstrate that this proposed process can generate 21.93 kg/s of fresh water, 346.1 kg/h of green hydrogen, 2739 kg/h of green oxygen, and 19,090 kW of power. Furthermore, the overall energy, exergy, electrical efficiencies, and total unit cost of the product for this new process are determined to be 16.44%, 53%, 8.7%, and 4.56 $/GJ, respectively. Additionally, through exergy analysis, it is established that the Proton Electrolyte Membrane Electrolyzer boasts the highest efficiency within the proposed process, with an exergy efficiency of 88.84%. Its contribution to the total irreversibility of the system is calculated at 1%. Moreover, the analysis reveals that the combined flash and binary geothermal system is the most significant contributor to irreversibility, accounting for 58% of the total, while turbine 2 represents 35.53% of the system's overall irreversibility. From an environmental perspective, employing this proposed process for power generation leads to an annual saving of 44,482,754 liters of petroleum. From an economic standpoint, the total investment cost of the proposed process amounts to $20,743,728. Among the subsystems, the combined flash-binary geothermal system incurs the highest investment cost, representing 41% of the total, while the proton electrolyte membrane electrolyzer has the lowest cost share at 6%.