There has been a surge of interest in electric power generation from low-temperature geothermal energy. The organic Rankine cycle is reviewed for efficiency. A pressure-enthalpy diagram for R-114 (the refrigerant chosen for this study) is given. In the cycle, refrigerant is vaporized, then expanded, to turn the shaft, then condensed, then pumped back into the cycle. The cycle depends on the difference between the evaporating pressure and the condensing pressure. The higher the geothermal water temperature, and the lower the cooling water temperature, the higher the work. Heat loss due to radiation and convection, the movement of refrigerant fluid through the evaporator, in the conversion of expanded power to electrical power, and in use of some actual produced power to pump the cooling water and drive the tower fans--all these heat losses are calculated. The overall saleable power efficiency of the cycle is determined. The efficiency is low, but the binary generator can find a place in a carefully conceived process