Exergy analysis of a binary geothermal power plant is performed using actual plant data to assess tile plant performance and pinpoint sites of primary exergy destruction. Exergy destruction throughout the plant is quantified and illustrated using an exergy diagram, and compared to the energy diagram. The sites with greater exergy destructions include brine reinjection, cat exchanger and condenser losses. Exergetic efficiencies of major plant components are determined in an attempt to assess their indiviJual performances. Tile energy and exergy efficiencies of the plant are 4.5% and 21.7%, respectively, based on the energy and exergy of geothermal water at the heat exchanger inlet. The energy and exergy efficiencies are 10.2% and 33.5%, respectively, based on the hea input and exergy input to the binary Rankine cycle. The effects of turbine inlet pressure and temperature and the condenser press ire on the exergy and energy efficiencies, the net power output and the brine reinjection temperature are investigated and the trends;ire explained. (c) 2008 Elsevier Ltd. All rights reserved.