From economic to exergo-economic modeling of geothermal power plant

Economic assessment of power plants is one of the most critical steps before starting the project. Nowadays, investors and governments are looking for energy systems with lower investment costs leading to a shorter payback period. In the present research, economic and exergo-economic analysis of geothermal power plants has been conducted. This study has been divided into four different sections, (I) geothermal well drilling cost model generation, (II) power plant's equipment cost model generation, (III) entire geothermal power plants' economic model generation, and (IV) exergo-economic analysis of three geothermal case studies based on previous sections. QUE$TOR software is applied to calculate the costs of well drilling and power plant equipment, which is a robust and reliable cost estimator tool for well drilling and equipment costs, including a comprehensive cost database. Curve fitting and different optimization approaches have been applied in the models' generation process to reduce the deviations and calibration of obtained coefficients. The well drilling cost models are generated for different regions and countries based on the well number and depth. Also, the power plant's equipment cost models are proposed for the pump, heat exchangers, compressor, air-cooled condenser, and pressure vessel. Generated cost models are the most updated correlations based on the 2020 database. The generated equipment models are implemented in the entire power plants’ economic models generation. Considered models are the total cost rate, plant’s total cost, and power generation cost. The evaluated geothermal configurations are simple Organic Rankine Cycle (ORC), regenerative ORC, single flash, double flash, and flash-binary cycles. The proposed cost models in all sections are compared with other references, and it shows good compatibility with available literature. In the last part of this study, based on the generated well drilling and equipment cost models, exergy and exergo-economic assessment of three different geothermal case studies are performed. The first case is the Kizildere geothermal power plant (in Turkey), a triple-flash cycle coupled with an ORC unit. The second case is the Castelnuovo geothermal power cycle planned to construct in the Tuscany region, Italy. It is composed of an ORC cycle with a district heating system and total reinjection of non-condensable gases. And the last case is a improved scheme of Castelnuovo cycle with adding LiBr-H2O absorption chiller and Polymer Electrolyte Membrane (PEM) electrolyzer to generate more products.