A binary cycle is a method for generating electrical power from geothermal resources and employs two separate fluid cycles, hence binary cycle. The primary cycle extracts the geothermal energy from the reservoir, and secondary cycle converts the heat into work to drive the generator and generate electricity.
Binary cycles permit electricity generation even from low temperature geothermal resources (<180 °C) that would otherwise produce insufficient quantities of steam to make flash power plants economically viable. However, due to the lower temperatures binary cycles have low overall efficiencies of about 10–13%.
