Optimization of geothermal- and solar-driven clean electricity and hydrogen production multi-generation systems to address the energy nexus

Abstract

Given the limited sources of fossil fuels, mankind should find new ways to meet its energy demands. In this regard, geothermal and solar energy are acknowledged as reliable, safe, promising, and clean means for this purpose. In this research study, a comparative analysis is applied on geothermal- and solar-driven multi-generation systems for clean electricity and hydrogen production through energy and exergy assessments. The systems consist of an organic Rankine cycle, a proton electrolyte membrane electrolyzer, and a thermoelectric generator subsystem. The Engineering Equation Solver software has been utilized in order to model the system and obtain the output contours, sensitivity analysis, and exergy destruction. The results were obtained considering the ambient temperature of Bandar Abbas city as a case study. The geothermal system was performant over the solar system, with 11.21% higher hydrogen production and 0.17 % higher exergy efficiency. According to the sensitivity analysis, the turbine efficiency, evaporator inlet temperature, thermoelectric generator suitability criterion, pump efficiency, and evaporator inlet mass flow rate were the most influential parameters. Also, the exergy analysis showed that the utmost system's exergy destruction is pertinent to the evaporator and the least is related to the pump. In addition, the system produces 352,816 kWh and 174.913 kg of electrical power and hydrogen during one year.

Keywords

• Geothermal energy
• Solar energy
• Exergy analysis
• Multi-generation system
• Electricity
• Hydrogen Production