A geothermal and solar-based multigeneration system integrated with a TEG unit: Development, 3E analyses, and multi-objective optimization

Abstract

A novel hybrid renewable-energy-based system for generating multiple commodities is investigated in this study. The heat gained from geothermal and solar energy sources is converted into useful products such as electricity, domestic hot water, cooling load, and hydrogen via an integrated energy system including parabolic trough collectors, a Kalina cycle, an ejector refrigeration system, a thermoelectric generator (TEG) unit, an organic Rankine cycle, and a PEM electrolyzer. A comprehensive analysis based on energy, exergy, and exergoeconomic methods is carried out to examine the system from different standpoints. To achieve the finest solution, multi-objective optimization is performed to simultaneously maximize exergy efficiency and minimize the total unit cost of products. The results indicate that, under the optimal condition, the system can attain 35.2% and 37.8 $/GJ, and 1.9 kg/h for exergy efficiency, the total unit cost of products, and hydrogen production rate, respectively. Moreover, by comparing system performance for the base case through a parametric study with and without TEG, it is determined that utilizing this unit could be more beneficial for the total system. However, the result achieved from a case study suggests that it would be economically wise to remove the TEG unit during some cold months.