For almost a century, wet evaporative cooling towers have been the predominant choice of heat rejection systems for power plants not situated on a large body of water. In 1939, the first air cooled condenser was placed into operation providing the power industry with a dry cooled solution. This was required for power plants located in arid areas or where sufficient quantities of make-up water were unavailable. From that point forward, if enough water was available, power plant developers installed wet cooled systems. Water availability at anything less than what was required for a 100% wet system, a 100% dry cooled system would be selected or another location for the power plant would be considered. The initial cost of a dry cooled system is 3 to 5 times greater than a wet cooled system. This, coupled with the fact that heat rejection performance during the summer months is reduced has maintained wet cooling as the preferred solution.
Conventional wisdom suggests that a power plant location requires access to a large body of water. If an adequate water source is missing, then the location would be abandoned unless the project’s economic model could support a dry cooled option. Many good locations have been discarded simply due to minor shortfalls in water availability.
It wasn’t until the early 1990’s that consideration was given to combining wet and dry cooling technologies to provide an alternative water saving condensing solution for power plants. Parallel condensing represents a symbiosis (hybrid) of wet and dry cooling solutions. The hybrid configuration offers significant water savings over conventional wet cooling and substantial cost savings and performance benefits over 100% dry cooled systems