Evaporative cooling technologies take advantage of both air and water to extract heat from a power plant. By utilizing both water and air one can reduce the amount of water required for a power plant as well as reduce the footprint required for an air cooling system. Evaporative cooling towers are commonly used in any thermal generation technologies (i.e. coal, natural gas, geothermal, CSP, etc). Evaporative cooling towers flow air over the cooling water to induce evaporation of the cooling water and simultaneously condense the steam exiting the turbine back into a liquid state. Evaporative cooling towers are able to circulate most of the cooling water that is available, greatly reducing the plant's water consumption. Since the water is evaporating off make up water is required, but typically in the magnitude of 2-5% of the total flow.
From Open Energy Information
Evaporative Cooling Tower