Natural draught cooling towers are inevitable for the economic generation of electricity under environmental aspects: In any thermal power plant heated stearn drives a turbogenerator, which produces the electric energy. In order to create an effective heat sink behind the turbine, the stearn is condensed and recyc led into the boiler. This requires a large amount of cooling water which is heated by running through the condensor. Even in the most efficient fossil fuel thermal (nuclear) power plants, only about 40 (30)% of the generated heat is turned in to electric energy. The rest of heat of 60 (70)% is discharged into the environment through the smokestack and the cooling wa ter circuit. To avoid thermal pollution of natural water resources the heated cooling water should be recooled artificially in a cooling sys tem and reused. Among all technical solutions natural draught cooling towers are effective, economic and widely spread cor rective measures. In large power plants only natural draught cooling towers are able to recover the immense quantities of water required for cooling. Thus only these engineering struc tures are able to balance environmental factors, economic in vestment and operating costs of the power station with the de mands of a reliable electric energy supply.