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

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.

Automated summary

This study investigates a novel hybrid renewable-energy-based system that can generate multiple commodities. By converting the heat from geothermal and solar energy sources, the system is able to produce useful products such as electricity, domestic hot water, cooling load, and hydrogen. The system includes various components such as parabolic trough collectors, a Kalina cycle, an ejector refrigeration system, a thermoelectric generator (TEG) unit, an organic Rankine cycle, and a PEM electrolyzer. Through a comprehensive analysis using energy, exergy, and exergoeconomic approaches, the system is examined from different perspectives. Multi-objective optimization is performed to achieve the best solution, maximizing exergy efficiency and minimizing the total unit cost of products. The results indicate that under optimal conditions, the system can achieve high exergy efficiency, low total unit cost of products, and a significant hydrogen production rate. Comparing the system performance with and without the TEG unit, it is found that utilizing this unit is more beneficial. However, a case study suggests that removing the TEG unit during certain cold months would be more economically wise.