While wet cooling ensures high efficiency for the power generation cycle, the associated evaporation and blow-down of cooling water imposes various environmental and ecological impacts:

• The humid plume emitted by the wet cooling tower contributes to visible fog formation and icing of roads in cold weather.
• The constant evaporation and blow-down of cooling water requires substantial amount of make-up water, that curtails its availability for municipality, industrial and agricultural consumption.

In order to eliminate this problem, cooling towers use the principle of combined wet and dry cooling. In this system an intense mixing of the air streams from the dry section and the wet section of the cooling tower takes place to obtain discharge air conditions which will avoid the development of plumes.