The project includes 17,500 heliostat mirrors that collect and focus the sun's thermal energy to heat molten salt flowing through an approximately 540-foot (160 m) tall solar power tower. The molten salt circulates from the tower to a storage tank, where it is then used to produce steam and generate electricity. Excess thermal energy is stored in the molten salt and can be used to generate power for up to ten hours, including during the evening hours and when direct sunlight is not available