Gypsum storage at a power station. Piles of limestone and gypsum inside a storage building at a coal-fired power station. Gypsum (calcium sulphate) is a byproduct of the scrubbers used to clean sulphur dioxide from the smoke produced by burning coal. This is the Drax power station near Selby, North Yorkshire, UK. As of 2006, Drax is the largest, cleanest and most efficient of the UK's coal-fired power stations. It can burn 36,000 tones of coal a day to produce 4,000 megawatts of power, around 7% of the UK's electricity needs. It was built from 1974-1986. For an external view of the gypsum storage building, see T190/445.