Sunset near a power station. The cooling towers of a large power station silhouetted against the setting Sun. Cooling towers cool the 'secondary loop' water. The primary loop water is converted into steam in the boilers, and is used to drive steam turbines and thus the generators. The secondary loop cools the primary loop water in heat exchangers, converting it back into water to be returned to the boilers. This photograph was taken at the Drax coal-fired power station, North Yorkshire, England.