These concave mirrors concentrate the light (& heat) from the sun towards the tube in the center. The tube is filled with a synthetic heat transfer oil, heated by the mirror's light to around 750 F (400 C). This superheated oil is then pumped from the solar field to a nearby power block, where the oil's heat is converted to high-pressure steam in a series of heat exchangers. This steam pushes a conventional steam turbine, creating electricity.