Investigation of geothermal energy supported multi-generation power generation system in terms of thermodynamics and economics

Addressing global warming and environmental issues involves the significant use of renewable energy sources. Renewable energy-supported combined power generation systems can enhance energy efficiency and utilization of renewable resources. This thesis explores a geothermal energy-supported combined multi-generation power system aimed at producing power, heating, drying, clean water, and compressed hydrogen. The proposed system comprises a single-flash geothermal power cycle, a transcritical CO2 Rankine Cycle, a multi-effect desalination unit, two thermoelectric generators, a dryer, and PEM electrolysis and compression units. Comprehensive thermodynamic and economic analyses were conducted to evaluate the system's efficiency and cost. Detailed energy and exergy efficiency analyses, along with exergy destruction analyses, were applied to each system component to determine overall system efficiency. Additionally, parametric analyses were performed to examine the impact of key parameters like geothermal source temperature, geothermal mass flow rate, heat exchanger compression point temperature, and regenerator efficiency on system performance. Results indicate that the combined system's net power generation is 1 585 kW, and hydrogen production is 0.00222 kg/s. The system also has a hot water production capacity of 4 851 kW and a clean water production capacity of 4.47 kg/s. The overall energy efficiency of the system is calculated at 23.18%, and exergy efficiency at 28.43%. The total system cost is estimated at $171.2/h. Based on these analyses, the proposed multi-generation power system demonstrates advantages in terms of efficiency and sustainability.