Thermodynamic analysis of geothermal and solar assisted power generation and heating system

Abstract

In this study, thermodynamic modeling and analysis of geothermal and solar-assisted cogeneration energy systems to supply the electricity and heating requirement of residences in Afyonkarahisar province are performed. In the system considered, electricity is generated in the Organic Rankine Cycle (ORC) with thermal energy obtained from geothermal and solar resources. The generated electricity is given to the network according to the energy requirement. When the grid's energy requirement is low, the excess electricity is sent to the electrolysis unit, and hydrogen is produced and stored. When energy is required again in the grid, the fuel cell's hydrogen energy is converted into electrical energy and given to the grid. The heat energy released from the cycle as waste heat in the ORC cycle is used in residential heating. The thermodynamic performance evaluation of the system has been performed in the Engineering Equation Solver (EES) software using the geothermal and solar energy values of Afyonkarahisar province. The parametric study of the system is carried out at different geothermal source temperatures and solar radiation values. In Afyonkarahisar, the geothermal water temperature is between 70 and 130°C, and the mass flow is between 70 and 150 kg/s. Also, solar radiation varies between 300 and 1000 W/m2. Total power generation in geothermal and solar assisted ORC cycle is 2420 kW. If this power generation is used to generate hydrogen directly in the electrolysis unit, 0.0154 kg/h of hydrogen is generated from the system. The heating capacity of the system for residential heating is 8933 kW. The overall system's energy and exergy efficiency has been calculated as 34.5% and 46.0%, respectively.