Keywords: cost values, exergy destruction, exergetic renewability, exergetic re–injection, exergoeconomics, geothermal energy, geothermal power plants, exergy analysis, thermodynamics, electricity generation, exergy cost
Exergoeconomic evaluation of a geothermal power plant
In this study, exergy and exergoeconomic analyses of the Dora II geothermal power plant (DGPP) with 9.5 MW net power output are carried out by using real thermodynamic and cost data. The exergetic efficiency of this plant is calculated to be 29.6%. The highest exergy destruction rate among the DGPP components occurs in the cooling towers followed by the turbines, vaporisers, preheaters and pumps. For exergoeconomic analysis, the cost balance equation for each component is written based on certain parameters and auxiliary equations to determine the cost values of exergy destruction. The costs of exergy destruction and electricity produced are determined based on the analysis and data used. The cooling tower I exhibits the greatest exergy destruction cost, followed by the turbines. The present results show that the unit cost of electricity produced and the exergy cost of geothermal fluid are 5.3 cents/kWh and 1.67 cents/kWh for DGPP, respectively.