Energy, vol.46, no.1, pp.101-108, 2012 (Journal Indexed in SCI Expanded)
An exergy analysis of the Dora II geothermal power plant (DGPP) with 9.5 MW net power output is carried out by using actual plant data to evaluate plant performance and pinpoint the locations of exergy destructions/losses. It aims to determine exergy efficiencies, and exergy destructions in each component of the plant. Exergy destructions in each of the components of the whole plant are determined and illustrated based on the actual data. The exergy destructions/losses take place through losses in the vaporizer, preheater, turbines, pumps and cooling tower, and the re-injection of the geothermal fluid. The exergy destruction ratios for these units and processes accounts for 7.97%, 1.25%, 11.93%, 1.3%, 14.92% and 32.18% of the total exergy input to the plant, respectively. Among the observed components in the plant, the most efficient equipment is found to be the preheater with an exergy efficiency value of 98%. The overall energetic and exergetic efficiencies of the plant are calculated to be 10.7% and 29.6%, respectively. The results show that geothermal energy can make a significant contribution toward reducing the emissions of greenhouse gases.