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EN10 - Percentage and total volume of water recycled and reused.

A large amount of the water withdrawn for use at power generating facilities is recycled or reused (Table 2), such as water that is used for cooling at facilities that have closed-cycle cooling.  Sixty-one percent (23,307 MW) of AEP’s steam-generated capacity is derived from plants with “closed” cooling systems.  While these systems are not entirely “closed,” as some water is lost due to evaporation in the cooling towers, they do withdraw significantly less water than once-through or open cooling systems.  At a typical 600 MW coal combustion unit with once-though cooling, up to 400,000 gallons per minute of cooling water is needed to cool the condensers (Figure 1).  For a similar 600 MW unit that utilizes closed-cycle cooling, only 5300 gallons per minute of cooling water is needed (Figure 2). 

Water is also recycled at many of the western plants that are on cooling water reservoirs (Arsenal Hill, Comanche, Flint Creek, Knox Lee, Lieberman, Lone Star, Pirkey, Welsh and Wilkes).  These reservoirs were specifically built in order to be both the source and receiving water body for the cooling water used at these plants.  Assuming negligible loss of water due to evaporation, these facilities “recycle” nearly 100% of the water that they withdrawal.  Since the cooling lakes are typically large, open bodies of water, they also provide public fishing and recreational boating.

Water used for other non-cooling purposes is also recycled.  For example, water used for bottom ash transport, pyrites transport, and other processes is directed to waste water ponds for treatment (Figures 1 & 2).  After treatment, this water is directed to reclaim ponds from which a significant portion is recycled and used again.  At a typical 600 MW coal-fired facility, approximately 50% of the process water is recycled (Figures 1 & 2).  At a once-thru cooled facility, this recycled water represents an insignificant amount of water, but at a closed-cycle facility, this recycled water can represent up to 20% of the total amount of water used by the facility (Figure 2).  On average, AEP recycles approximately 25% of the water that it withdrawals from water sources.

 

 

2012