Energy and Exergy Analysis of Sabalan Geothermal Power Plant, Iran

Abstract

The Sabalan geothermal field in northwest of Iran is currently under development. A single flash cycle has been selected for power generation. The obtained results show that the maximum power output from the plant can be 36 MWe with pressures equal to 5.5 and 0.3 bar for separation step and condenser, respectively. Mathematical models for energy and exergy flows were developed and implemented in the Engineering Equation Solver (EES) software. A few assumptions and simplifications were made. The energy and exergy rates of the waste brine have been calculated as 54.8% and 41.4% of the total available energy and exergy rates, respectively. The separated brine can be used as a heat source for a combined power production, district heating system or some other forms of direct use. Reinjection should also be taken into account. The parts of the system with largest exergy destruction are the condenser, the turbine, and the disposed waste brine. The overall exergy efficiency for the power plant is 32.73% and the overall energy efficiency is 7.32%. Exergy analysis was found helpful and important tool for analyzing the geothermal plant from the view point of optimum usage of stored energy and should be considered at early stages of designs.