On 16 August 1916,[22] Frederik van Iterson took out the UK patent (108,863) for Improved Construction of Cooling Towers of Reinforced Concrete.[23] The patent was filed on 9 August 1917, and published on 11 April 1918. In 1918, DSM built the first hyperboloid natural-draft cooling tower at the Staatsmijn Emma, to his design.
Hyperboloid (sometimes incorrectly known as hyperbolic) cooling towers have become the design standard for all natural-draft cooling towers because of their structural strength and minimum usage of material.[24][25][26][27] The hyperboloid shape also aids in accelerating the upward convective air flow, improving cooling efficiency.[28][29] These designs are popularly associated with nuclear power plants. However, this association is misleading, as the same kind of cooling towers are often used at large coal-fired power plants and some geothermal plants as well. The steam turbine is what necessitates the cooling tower. Conversely, not all nuclear power plants have cooling towers, and some instead cool their working fluid with lake, river or ocean water.