EN8 - Total water withdrawal by source

Steam Electric Facilities
Water is critical to the operation of most power generating facilities for steam production and plant cooling purposes. Power plants withdraw, but do not consume, large amounts of water. The largest AEP once-through cooled plants can withdraw up to 2.37 billion gallons of water per day from the source water body when operated at maximum design flows.

Using 2007 as an example year, the average annual rate of cooling water withdrawal, for all AEP power plants, was approximately 7.4 billion cubic meters or nearly 5.9 billion gallons of water per day (Table 1). Despite the large withdrawal of water at AEP power plants, most of the water is used for once-through cooling in steam condensers and is returned to the source water body almost immediately. Water that is used for cooling in the steam condensers at plants that have closed-cycle cooling systems is actually recycled. This cooling water is routed through cooling towers to reduce the amount of heat in the water and then recycled back into the plant for reuse in the cooling process. U.S. EPA has estimated that closed-cycle cooling systems such as these require only 5 percent of the water that once-through cooling systems require (U.S. EPA 1982).

Water used for other purposes, such as coal ash removal from generating units, steam make-up, or equipment cooling, is also returned to the source water bodies. However, this water must first be treated to meet effluent limits specified in National Pollution Discharge Elimination System (NPDES) permits before it can be released to the source water bodies.

AEP 2007 power plant water use (based on information contained in the Steam Electric Plant Operation and Design Report for the year 2007).