Energy and exergy analysis of a multi-generation system for power, freshwater, and hydrogen production using geothermal water
摘要
An innovative configuration of multipurpose production systems harnessing renewable solar and geothermal energy for the generation of green hydrogen fuel and freshwater is presented in this research. The integrated system comprises a thermal/photovoltaic system, an organic Rankine cycle, an alkaline electrolyzer, and a reverse osmosis water desalination unit. The main required thermal energy and salt water is provided by geothermal water. In the thermal photovoltaic system, a half-tube structure is employed to enhance the contact between the working media and the collector surface. In addition, to enhance the cooling process of the solar system, TiO2/water nanofluid is utilized. As a result of incorporating the nanofluid, the electrical and thermal efficiency of the solar system reaches around 12, and 82%, respectively. The proposed desalination unit requires a power supply of 40 kW, which is provided by the solar system. Geothermal water, with a flow rate of 12.1 kg s−1 and a temperature of 154 °C, supplies the thermal energy needed for the organic Rankine cycle, which uses isobutane as the working media. The organic Rankine cycle, in turn, generates the 671 kW of power required for the alkaline electrolysis system. The integrated system demonstrates an exergy efficiency of 43%. Assuming that all the electricity generated by the organic Rankine cycle is utilized for hydrogen production, the system achieves a final production rate of 1.397 kg s−1 of freshwater and 18.5 kg h−1 of hydrogen. The initial capital investment for the proposed system is estimated to be 1.98 MM$, with an anticipated payback period of approximately 4 years.