Binary cycles are the most common method to extract energy from moderate geothermal resources worldwide. This research investigates and compares the performance of Organic Rankine Cycle (ORC) for binary geothermal power plants from the thermodynamic point of view. A hypothetical ORC cycle which is using 150°C geothermal water as a heat source was considered in this study and its exergy and energy analysis were performed. A parametric study was also performed to understand the effect of ambient temperature and its effect on both energy and exergy efficiencies. The exergy and energy efficiencies, cooling water pump power consumption and also exergy destruction for each component are calculated within different ambient temperature and dead state as well. The results indicated that energy efficiency of the plant varies by 1 and 7% in two different scenarios that were assumed based on different control volume description for the system. Scenario (a) and (b) are based on brine exergy input rate to plant and exergy flow rate decrement across heat exchanger, respectively. Meanwhile, exergetic efficiencies of the cycle face 70%; and 34% increment based on different exergy inflows scenarios. It was concluded that condensers are the most sensitive component to dead state temperature.