Conventional light water reactors resemble a coal fired power plant in overall design, in that a boiler is used to produce steam which then drives a steam turbine to produce electricity. The boiler is the only significant difference. In a coal plant, this normally consists of a system to burn the coal while water circulates through the boiler in a series of tubes. The water is held under pressure in order to increase its boiling point, which makes the turbines more efficient.