Utility-scale geothermal power plants in the United States use either steam power or a binary cycle to generate electricity. Of the 2,558 megawatts (MW) of geothermal power plant capacity currently operating in the United States, 1,826 MW of capacity is from steam-powered plants and 731 MW of capacity is from binary-cycle powered plants. Unlike steam-powered geothermal power plants, which use steam directly from a geothermal well to spin a turbine and generate electricity, binary-cycle geothermal power plants use a heat exchanger to take heat from the hot water to heat a secondary fluid that then spins a turbine.