Geothermal power. Interior of a geothermal power station. Here, superheated water from below the ground is used to heat water and drive electricity-generating 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 also has no waste products, making it clean and environmentally friendly. Photographed in 2003.