Geothermal power station. Steaming chimneys at a steam separation plant at a geothermal power station. Here, superheated water from below the ground is used to heat water to drive electricity- generating turbines. The steam separator removes water from the steam, so that it does not reduce the efficiency of the turbines. This is the Nesjavellir plant in Iceland. Iceland lies on the boundary between two tectonic plates (on which the continents are carried). It is a highly geologically active area, and much of its energy is derived from renewable sources. Geothermal power has no waste products, making it clean and environmentally friendly. Photographed in 2003.