Gemasolar power plant. Satellite image of the Gemasolar thermal power plant, Seveille, Spain. The plant consists of a 140 metre tall tower surrounded by 2,650 heliostats (mirrors that track the Sun's movement). The heliostats focus reflect sunlight on to a receiver at the top of the tower. The sunlight is used to heat molten salt, which either stores the heat, or uses it to heat water to create steam to drive turbines. Image obtained by the GeoEye-1 satellite.