Multi-objective optimization and multi-aspect analysis of an innovative geothermal-based multi-generation energy system for power, cooling, hydrogen, and freshwater production

Abstract

Considering the feasibility of geothermal wells employed worldwide in the energy sector, this study was motivated to examine a novel multi-generation system devised to enhance the feasibility of flash-binary geothermal systems through innovative heat recovery in five stages. Accordingly, the main system consists of a flash-binary geothermal cycle, an ejector refrigeration cycle, a Kalina cycle integrated with another ejector refrigeration cycle, a humidification dehumidification desalination unit, and a low-temperature electrolyzer. Due to the five stages of innovative heat recovery, this system achieved a cost-effective and efficient design framework, introducing it as a high-quality alternative for stand-alone flash-binary geothermal cycles. To study the feasibility of the proposed system, a sensitivity analysis based on energy, exergy, and exergoeconomic concepts was employed. Moreover, the genetic algorithm in different multi-objective optimization scenarios was implemented to reach stable and high-efficiency products. According to the obtained results, the capability of the system to produce electricity, cooling, freshwater, and hydrogen are calculated to be 782 kW, 881.6 kW, 0.286 kg/s, and 0.181 kg/h, respectively. Also, in the exergy-cost optimization scenario, the system's optimum exergy efficiency and sum unit cost of products were obtained to be 46.44% and 3.98 $/GJ, respectively based on LINMAP decision-making method.