Power-generating plants use evaporation to cool their hot water.

Cooling towers at a power-production facility

Thermoelectric power plants, including Plant Bowen in Georgia, generate electricity by using heat (in this case, from burning coal) to convert water into steam that is pumped through pipes to turn the blades of a turbine, which is connected by a shaft to a generator. The generator spins and produces electricity. The steam, very hot and under a great deal of pressure, is condensed using large amounts of cooling water and the heat transferred to the cooling water is cooled (by a recirculating cooling tower, a once-through cooling system, or a recirculating pond). Plant Bowen, uses recirculating cooling towers, where hot water is sprayed inside, and evaporation is used to cool the water before it is returned to the condenser to the be used again.

There are a lot of different types of power-generating plants, but thermoelectric power plants withdraw lots of water (which is why they are often located alongside rivers and other water bodies) to both generate electricity and to cool the steam used to generate electricity. Releasing hot water back into rivers would harm the ecology, so many power plants have tremendous cooling towers, where hot water is sprayed inside and evaporation is used to cool the release water before it goes back into the environment.