Because of the limited amount of the fossil fuel sources, it is becoming popular to search new energy sources to produce electricity. Although Turkey is the second country to have the highest geothermal potential in Europe, electricity production front geothermal energy is quite low. The purpose of this article is to search for the possibility of the electrical energy generation by binary system operated with various working fluids at different geothermal fluid temperatures. Although in the range of 121-167 degrees C geothermal fluid temperatures hydrocarbons can be used as secondary fluid, between 150-230 degrees C hydrocarbons cannot be used, so ammonia must be considered. Also at 121-130 degrees C range if the flow rate is high, ammonia must be used as a secondary fluid.