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EU EN8 - Water used for Processing, Cooling and Consumption in Thermal and Nuclear Power Plants, including use of Water in Ash Handling

As mentioned above, water is critical to the operation of most power generating facilities, particularly steam electric facilities.  Besides cooling, water is used for bottom ash and fly ash transport, cleaning, low volume waste transport, and in the boilers themselves.  The following description of water use is based on a detailed preliminary engineering study of steam electric facilities provided by the US EPA (USEPA 2005).  For example, in a typical fossil fuel-fired facility, fuel, such as coal, is conveyed into a boiler, where it is burned to generate steam.  The steam leaves the boiler and enters a turbine generator, where it drives turbine blades.  After leaving the turbine, the steam enters a condenser, where it is cooled by cooling water flowing through the condenser tubes. 

A constant flow of cooling water is required to cool the condenser.  Once-through or recirculating cooling water systems are used.  In a once-through system, the cooling water is withdrawn from a source of water, such as a river or lake, flows through the condenser, and is returned back to the source water.  In a recirculation system, the warmed cooling water is cooled in cooling towers or ponds, and is recirculated to the condenser.  In a recirculating system, a small amount of water must be continuously discharged to control the buildup of solids.  Make-up water is added to replace this water as well as water lost through evaporation.  Though data are not available for every AEP recirculating system, for a large 2900 MW facility cooled with cooling towers during 2010, of the 30 million gallons per day (MGD) of water used for cooling, approximately 26 MGD are lost to evaporation or drift (Amos Plant, Table 2).  At another facility cooled by cooling towers, 60 MGD of water are used for cooling and 52 MGD are lost to evaporation or drift (Gavin Plant, Table 2).  At the AEP Cook Nuclear plant, which is a once-through cooled facility, on average, 1988 MGD of water was withdrawn and used for cooling in 2009.  Since it is a once-through cooled facility, almost no water is lost to evaporation or drift (less than 4%, NETL 2010); however, much more water is withdrawn to cool the condensers.

Two types of ash are produced during the combustion of coal: bottom ash and fly ash.  After collection, the fly ash and bottom ash may be managed separately or together in landfills or in wet surface impoundmentsIf managed in surface impoundments, water is used to sluice the ash to ash ponds.  During 2010, AEP used approximately 134 MGD of water for ash handling at coal-fired facilities (Table 2).  Typical use of ash handling water at coal fired facilities varied from 0.3 MGD at the Clinch River Plant to 28 MGD at the Conesville, a large 1695 MW facility (Table 2).

Process water use at a typical fossil-fueled facility includes water used for cooling water make-up, treatment, such as in the flue gas desulfurization process (wet scrubbers), and maintenance cleaning.  During 2010, AEP used approximately 171 MGD of water for process purposes (Table 2).  Process water use ranged from a high of 23 MGD at the Conesville facility to a low of 0 MGD at the Weleetka Plant (Table 2).

Table 2.  Water used during 2010 for processing (excluding stormwater and sewage), cooling and consumption in thermal and nuclear power plants, including use of water in ash handling.

Facility Water Source Total Water Withdrawal MGD Cooling Water Use MGD Ash HandlingWater Use MGD Process Water Use(MGD) Net Water Consumption MGD Water
Recycled
(MGD) (%)
Amos Kanawha River 36.40 29.90 8.64 2.34 25.50 4.48 12
Arsenal Hill/Stall 12 Mile Bayou 1.30 1.03 0.00 0.44 0.04 0.17 13
Big Sandy Big Sandy River 12.65 9.52 3.05 3.91 8.26 3.82 30
Cardinal Ohio River 698.49 691.16 9.04 6.66 4.88 8.37 1
Ceredo - CT Ground water$ Not measured --- --- --- --- --- ---
Clifty Creek Ohio River 1242.9 1216.42 4.10 22.38 14.52 0.00 0
Clinch River Clinch River 8.7 8.24 0.31 0.92 5.29 0.77 9
Comanche Lawton POTW 8.5 8.28 0.00 0.15 0.15 8.28 97
Conesville Muskingum River 121 79.71 27.76 23.39 16.27 9.86 8
Cook Lake Michigan 1988.3 1987.70 0.00 0.60 0.00 0.00 0
Darby - CT Ground water$ Not measured --- --- --- --- --- ---
Dresden Muskingum River 0.00 0.00 0.00 0.00 0.00 0.00 6
Flint Creek SWEPCO Lake 270.2 266.94 1.88 1.38 0.00 270.20 100
Gavin Ohio River 64.3 59.53 12.61 20.29 51.69 28.13 44
Glen Lyn New River 85.6 84.41 1.22 -0.03 0.05 0.00 0
Greenville - CT Ground water$ Not measured --- --- --- --- --- ---
Kammer Ohio River 288.2 284.84 2.51 1.31 0.34 0.47 0
Kanawha River Kanawha River 194.7 190.09 0.52 4.08 0.31 0.00 0
Knox Lee Lake Cherokee 166.9 164.64 0.00 2.26 0.00 166.90 100
Kyger Creek Ohio River 1053.2 1025.71 6.11 21.38 0.00 0.00 0
Lawrenceburg Tanners Creek 1.1 1.04 0.00 0.08 0.51 0.02 1
Lieberman Caddo Lake 218.1 215.21 0.00 2.89 0.00 218.10 100
Lone Star Ellison Creek Res. 0.1 0.10 0.00 0.00 0.00 0.10 100
Mattison - CT Ground water$ Not measured --- --- --- --- --- ---
Mitchell Ohio River 27.2 20.46 7.08 4.04 13.52 4.38 16
Mone - CT Ground water$ Not measured --- --- --- --- --- ---
Mountaineer Ohio River 15.4 10.85 7.83 4.41 11.37 7.69 50
Muskingum River Muskingum River 583.62 577.46 4.51 4.11 2.07 2.46 0
Northeastern Oologah Res. 26.2 24.81 5.83 1.06 16.21 5.50 21
Oklaunion Lake Diversion 5.6 4.95 0.61 0.40 5.60 0.36 6
Picway Scioto River 10.27 10.21 0.06 0.00 0.00 0.00 0
Pirkey Brandy Branch Res. 200.7 198.84 1.59 0.27 0.00 200.70 100
Riverside Arkansas River 0.7 0.71 0.00 0.01 0.01 0.02 3
Rockport Ohio River 29.4 23.18 6.33 7.14 19.35 7.25 25
Southwestern Ft. Cobb Res. 3.2 2.14 0.00 1.90 1.62 0.84 26
Sporn Ohio River 610.6 601.78 4.16 4.66 0.00 0.00 0
Tanners Creek Ohio River 587.9 572.95 8.66 6.29 0.00 0.00 0
Tulsa Arkansas River 0.3 0.29 0.00 0.01 0.16 0.00 0
Waterford Muskingum River 1.5 1.37 0.00 0.16 1.24 0.03 2
Weleetka - CT Ground Water$ Not measured --- --- --- --- --- ---
Welsh Welsh Res. 2382.1 2052.96 9.92 19.32 0.00 2082.20 87
Wilkes Johnson Creek Res. 74.5 71.78 0.00 2.72 0.00 74.50 100
  Totals: 11,020 10,499 134 171 198 3106  

$    Ground water use was not measured.

Hydroelectric Facilities
AEP operates 17 hydroelectric projects in Indiana, Ohio, Michigan, Virginia, and West Virginia (Table 3).  Under licenses granted by the Federal Energy Regulatory Commission (FERC), these projects, with the exception of Smith Mountain Lake, which is a pumped storage facility, are operated as “run of river.”  This means that the flow of water exiting the project must equal the flow of water entering the project.  On average, 41.7 billion cubic meters of water passes through these projects each year (Table 3), which is less than half, or 36 percent, of the mean annual flow through the source rivers.  This difference is due to the fact that at times, only a portion of the river flow goes through the hydroelectric turbines.  The remaining water flows over the dam spillways or through lock chambers on navigable rivers.

Table 3.  AEP hydroelectric project 2011 water use.

Facility State Type MW(1) Water Source Mean River Flow (2)
(x109 m3/yr)
Estimated Flow thru Units
(x109 m3/yr)

Elkhart

IN

Hydro

3

St. Joseph River

2.097

1.169*

Twin Branch

IN

Hydro

5

St. Joseph River

2.838

2.182

Berrien Springs(3)

MI

Hydro

7

St. Joseph River

3.097

2.389*

Buchanan

MI

Hydro

4

St. Joseph River

3.079

2.144

Constantine

MI

Hydro

1

St. Joseph River

1.214

0.788*

Mottville

MI

Hydro

2

St. Joseph River

1.472

1.180

Racine

OH

Hydro

48

Ohio River

50.871

9.799

Byllesby

VA

Hydro

22

New River

1.821

1.306

Buck

VA

Hydro

9

New River

1.821

1.483

Claytor

VA

Hydro

75

New River

2.820

2.666

Leesville

VA

Hydro

50

Roanoke River

1.356

1.068

Niagara

VA

Hydro

2

Roanoke River

0.482

0.246*

Reusens

VA

Hydro

13

James River

3.248

0.792

Smith Mountain

VA

Hydro

586

Roanoke River

0.892

0.697*

London

WV

Hydro

14

Kanawha River

11.093

3.879

Marmet

WV

Hydro

14

Kanawha River

11.494

5.068

Winfield

WV

Hydro

15

Kanawha River

15.404

4.836

Totals

 

 

870

 

115.099

41.692

(1) Installed capacity
(2) USGS Gauge Data
(3) Not a FERC Project, but regulated by the Michigan Dept. Natural Resources and Environment.
*  PI flow data not available; estimated flow based on 2010 generation.

Source Information - Steam electric plants – water balance diagrams are used to determine the percentage of water used for cooling, ash handling, etc.  These percentages are then applied to water withdrawal information from EN8 to estimate actual amount of water used for various plant processes.

Hydro projects – AEP Hydro Operations Data (D. Shirley).

USEPA report:  USEPA. 2005. Preliminary Engineering Report: Steam Electric Detailed Study. EPA-821-B-05-005. Washington, D.C. (August).

NETL.  2010.  Water Vulnerabilities for Existing Coal-Fired Power Plants.  National Energy Technology Laboratory.  DOE/NETL-2010/1429.  August 2010.


2012