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TitleWater and Energy: Leveraging Voluntary Programs to Save Both Water and Energy (2008)
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LanguageEnglish
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Table of Contents
                            Water and Energy: Leveraging Voluntary Programs to Save Both Water and Energy
	Cover
	Table of Contents
	List of Exhibits
	Executive Summary
	1. Introduction
	2. Overview of Water Use in the United States
		2.1 Water Withdrawal, Consumption, and Return
		2.2 Overview of Water Use: Withdrawal and Consumption
		2.3 Trends in Water Use
	3. Water Supply and Wastewater Treatment Systems
		3.1 Water Supply Systems
		3.2 Wastewater Treatment
		3.3 Linkage Opportunities with Energy Efficiency Programs
	4. Power Generation
		4.1 Water Uses at Power Plants
		4.2 The Rate of Water Consumption at Power Plants
		4.3 Dry Cooling
		4.4 The Water Impacts of Energy Efficiency
	5. Residential Water Consumption
		5.1 Residential End Uses
		5.2 Opportunities to Improve Residential Water Use Efficiency
		5.3 Water Prices and Billing
		5.4 Linkage Opportunities with Energy Efficiency Programs
	6. Commercial and Institutional Water Consumption
		6.1 Commercial and Institutional End Uses
		6.2 Opportunities to Improve Commercial and Institutional End Use Efficiency
	7. Leveraging Efficiency Programs to Improve Energy and Water Use Efficiency
		7.1 Energy Efficiency Programs
		7.2 The Impact of Energy Efficiency on Water Use in Power Generation
		7.3 Water Efficiency Programs
		7.4 The Impact of Water Efficiency on Electricity Usage at Water Supply and Wastewater Treatment Facilities
		7.5 Opportunities for Water Supply and Wastewater Utilities to Improve Energy and Water Use Efficiency Together
		7.6 Opportunities for Residential Customers to Improve Energy and Water Efficiency Together
		7.7 Opportunities Among Commercial Customers to Improve Energy and Water Efficiency Together
		7.8 Potential Water and Energy Savings Resulting From Leveraging Energy and Water Efficiency Programs
		7.9 Conclusion
	8. References
                        
Document Text Contents
Page 1

Water and Energy:
Leveraging Voluntary Programs to
Save Both Water and Energy




Prepared By:

ICF International
1725 Eye Street, Suite 1000
Washington, DC 20006



Prepared For:

Climate Protection Partnerships Division
and Municipal Support Division
U.S. Environmental Protection Agency
Washington, DC



March 2008




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i



Table of Contents

Executive Summary ..................................................................................................................................... vi
Overview of Water Use in the United States ...........................................................................................vii

Energy and Water Are Linked ................................................................................................................ viii

Opportunities for Energy and Water Efficiency....................................................................................... viii
Leveraging EPA Programs .......................................................................................................................ix

1. Introduction ..........................................................................................................................................1-1

2. Overview of Water Use in the United States .......................................................................................2-1
2.1 Water Withdrawal, Consumption, and Return...............................................................................2-1

2.2 Overview of Water Use: Withdrawal and Consumption................................................................2-2
2.2.1 Thermoelectric Power.............................................................................................................2-2
2.2.2 Irrigation..................................................................................................................................2-4
2.2.3 Public Supply..........................................................................................................................2-6
2.2.4 Remaining Uses .....................................................................................................................2-7
2.2.5 Per Capita Withdrawals by State............................................................................................2-7
2.2.6 Freshwater Consumption .......................................................................................................2-8

2.3 Trends in Water Use .....................................................................................................................2-8

3. Water Supply and Wastewater Treatment Systems............................................................................3-1

3.1 Water Supply Systems..................................................................................................................3-1
3.1.1 Water System Industry ...........................................................................................................3-2
3.1.2 Typical Water Supply Processes............................................................................................3-6
3.1.3 The Energy Intensity of Water Supply and Opportunities to Improve Efficiency....................3-9
3.1.4 Improving Water Delivery Efficiency: Water Loss Control....................................................3-12

3.2 Wastewater Treatment................................................................................................................3-19
3.2.1 Wastewater Treatment Industry ...........................................................................................3-19
3.2.2 The Energy Intensity of Wastewater Treatment ...................................................................3-26
3.2.3 Principal Electricity Uses at Wastewater Treatment Plants and Opportunities for

Improved Energy Efficiency..................................................................................................3-31

3.3 Linkage Opportunities with Energy Efficiency Programs............................................................3-36

4. Power Generation................................................................................................................................4-1

4.1 Water Uses at Power Plants .........................................................................................................4-1
4.1.1 Power Plant Cooling Water ....................................................................................................4-1
4.1.2 Other Uses of Water at Power Plants ....................................................................................4-3

4.2 The Rate of Water Consumption at Power Plants ........................................................................4-4
4.2.1 Cooling Water Consumption at Power Plants ........................................................................4-4
4.2.2 Other Uses of Water...............................................................................................................4-9

4.3 Dry Cooling ...................................................................................................................................4-9

4.4 The Water Impacts of Energy Efficiency.....................................................................................4-12

5. Residential Water Consumption..........................................................................................................5-1

5.1 Residential End Uses....................................................................................................................5-1

5.2 Opportunities to Improve Residential Water Use Efficiency .........................................................5-7
5.2.1 Measured Water Savings .......................................................................................................5-7
5.2.2 Cost Effectiveness................................................................................................................5-15

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4-7

Exhibit 4-3 shows that recirculating systems consume more water than once-through systems.
As shown in the exhibit, recirculating systems typically consume about 0.5 gallons per kWh,
while nearly all the once-through systems are substantially below that level. Summary statistics
for the available data include:15

• Once-through systems:

The average water consumption rate is about 0.11 gallons per kWh. This average is
influenced heavily by the relatively small number of observations with non-zero
consumption rates: 86 percent of the observations report no water consumption (all
the water withdrawn is reported as being discharged).

The median rate of water withdrawal is 54 gallons per kWh. The 25th and 75th
percentile values are 36 and 87 gallons per kWh, respectively.

Total electricity production from the plants in the data set was about 915 million MWh
in 2002, or about 24 percent of the national total.

The estimates are based on data for 285 power plants with only once-through
cooling systems and valid and complete data for purposes of performing the
calculations.

• Recirculating systems:

The average water consumption rate is 0.75 gallons per kWh. The median
consumption rate is 0.55 gallons per kWh. The 25th and 75th percentile values are
0.39 and 0.88 gallons per kWh, respectively.

The median rate of water withdrawal is 0.81 gallons per kWh. The 25th and 75th
percentile values are 0.57 and 1.9 gallons per kWh, respectively. These withdrawal
rates are on the order of 1.5 to 2.2 percent of the withdrawal rates for once-through
cooling systems.

Total electricity production from the plants in the data set was about 990 million MWh
in 2002, or about 26 percent of the national total.

The estimates are based on data for 209 power plants with recirculating cooling
systems and valid and complete data for purposes of performing the calculations.

These water withdrawal and consumption figures for cooling water are consistent with recent
estimates by CEC and EPRI (see Exhibit 4-4).

Because these values apply to steam condensing, they do not reflect the water intensity of
electricity production using combined cycle power plant configurations. Typically, the total
generating capacity of a combined cycle plant is two-thirds from combustion turbines and one-
third from steam turbine generation. Because the combustion turbines use no cooling water to
condense steam, the total cooling water consumption is associated only with the steam turbine
portion of the plant. As a result, water withdrawal and consumption per kWh for the complete
combined cycle plant is about one-third the value for the steam portion alone.

For example, a combined cycle plant may produce 480,000 MWh in a year, with 320,000 MWh
coming from the combustion turbine and 160,000 MWh coming from the steam turbine. If the
cooling water requirement for the steam cycle is 0.6 gallons per kWh, then the total cooling
water consumption would be 0.6 gallons/kWh x 160,000,000 kWh = 96 million gallons. This
cooling water requirement would then be divided by the total plant output of 480,000 MWh to


15 Note that the data for 2002 do not include nuclear power plants.

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calculate the total water consumption per kWh for the entire plant, which would be 0.2 gallons
per kWh.

The total cooling water consumption for all electric power production in the U.S. depends on the
mix of generating technologies used and the mix of cooling systems used. Unfortunately, the
data needed to match cooling system use to actual power generation is lacking (EPRI, 2002,
p. 4-5). As demonstrated above, there is wide variation in water consumption among plants and
between once-through and recirculating cooling systems. Additionally, the portion of power
produced by combustion turbines and combustion turbines in combination with steam turbines
(combined cycle) influences the average rate of water consumption.

Exhibit 4-4: Cooling Water Withdrawal and Consumption for Steam Plant Cooling



This Paper
Median

(25th to 75 th percentile) CEC (2002) EPRI (2002)
Once-through Cooling
Withdrawal Rate
(gallons/kWh)

54
(36 to 87)

30 to 45
20 to 50 (fossil)

25 to 60 (nuclear)
Consumption Rate
(gallons/kWh)

0
(0 to 0)a

Negligible About 1% of withdrawalb

Recirculating Cooling
Withdrawal Rate
(gallons/kWh)

0.81
(0.57 to 1.9)

0.6 to 0.9
0.5 to 0.6 (fossil)

0.8 to 1.1 (nuclear)
Consumption Rate
(gallons/kWh)

0.55
(0.39 to 0.88)

0.72
0.48 (fossil)

0.72 (nuclear)
a 86 percent of the observations reported no water consumption.
b Includes increased evaporation from the receiving body of water due to temperature increase in the
cooling water.
Values reported for steam cycle only. Not applicable to combined cycle power plant cooling. See text.
Estimates for this paper from analysis of EIA Form 767 data (EIA, 2004).


Recognizing these data limitations, EPRI estimated total cooling water consumption at
approximately 2,300 to 3,000 million gallons per day (mgd) for the year 2000 (EPRI, 2002,
p. 6-3).16 Given total annual electricity generation of about 3,800 million MWh in 2000 (EIA,
2007a), the average rate of water consumption is about 0.2 to 0.3 gallons per kWh. This
estimate is a total average across all electricity production, including electricity that does not
require cooling water (such as hydroelectric power and electricity from combustion turbines).

As discussed above, evaporation from streams and lakes may be increased by the higher
temperature of the water discharged from once-through cooling systems. For once-through
cooling the amount of evaporation may be on the order of 0.3 gallons per kWh, or about
one percent of the water withdrawal for this type of cooling (EPRI, 2002, p. 3-2). This figure is
included in the EPRI estimate of water consumption. Increased evaporation is not expected for
recirculating cooling systems because the water is cooled prior to its discharge (see Exhibit 4-
1).


16 The EPRI (2002) estimate is for freshwater consumption. Saline water consumption for cooling water is
expected to be very small because coastal cooling systems are typically once-through designs.
Consequently, the estimate of freshwater consumption is taken as total consumption.

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USEPA, 2001c. Technical Development Document for the Final Regulations Addressing
Cooling Water Intake Structures for New Facilities. U.S. Environmental Protection Agency,
Office of Water, Washington, D.C., November 2001, EPA-821-R-01-036.

USEPA, 2002a. Community Water System Survey. United States Environmental Protection
Agency, Office of Water, Washington, D.C., December 2002, EPA 815-R-02-005A.

USEPA, 2002b. Onsite Wastewater Treatment Systems Manual. United States Environmental
Protection Agency, Office of Water, Washington, D.C., February 2002, EPA/625/R-00/008.

USEPA, 2002c. The Clean Water and Drinking Water Infrastructure Gap Analysis. United States
Environmental Protection Agency, Office of Water, Washington, D.C., September 2002, EPA
816-R-02-020.

USEPA, 2003a. Best Management Practices for Colleges and Universities. Water Management,
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USEPA, 2003b. Clean Watersheds Needs Survey 2000, Report to Congress. U.S.
Environmental Protection Agency, Office of Wastewater Management, Washington, D.C.,
August 2003, EPA-832-R-03-001.

USEPA, 2003c. Clean Watersheds Needs Survey 2000 Unit Process ZIP File, The file includes
the detailed listing of the treatment and sludge handling processes used in the treatment of
wastewater at a facility as provided by individual States during the 2000 survey. U.S.
Environmental Protection Agency, Office of Wastewater Management, Washington, D.C.,
Accessed at: http://cfpub.epa.gov/cwns/process.cfm.

USEPA, 2004a. Climate Protection Partnerships Division, United States Environmental
Protection Agency, Washington, D.C.

USEPA, 2004b. Factoids: Drinking Water and Ground Water Statistics for 2003. United States
Environmental Protection Agency, Office of Water, Washington, D.C., January 2004, EPA
816-k-03-001.

USEPA, 2005. Water and Wastewater Focus. Fact Sheet, United States Environmental
Protection Agency, Washington, D.C. Available from www.energystar.gov.

USEPA, 2007a. WaterSense: Efficiency Made Easy, U.S. Environmental Protection Agency,
Office of Water, Washington, D.C., 2002. Accessed at:
http://www.epa.gov/watersense/tips/index.htm

USEPA, 2007b. Personal communication with US EPA’s Office of Water.

USEPA, 2007c. Climate Partnerships Protection Division, U.S. Environmental Protection
Agency, Washington, DC, G&A Sept 07 final. Location: G:\CPPD\USERS\CPPD Special
Assistant\Annual Reports\Annual Report 2006\Data

USEPA, 2008. Summary of the ENERGY STAR program is available at: www.energystar.gov.

USGS, 1998. Estimated Use of Water in the United States in 1995. United States Geological
Survey, Reston, Virginia, 1998.USGS, 1998. Estimates Use of Water in the United States in
1995, United States Geological Survey, Reston, Virginia, 1998.


USGS, 2000. Estimated Use of Water in the United States in 1995. U.S. Geological Survey,

U.S. Department of the Interior, Reston, Virginia, 2004, Circular 1200.

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8-10

USGS, 2004. Estimated Use of Water in the United States in 2000. U.S. Geological Survey,
U.S. Department of the Interior, Reston, Virginia, 2004, Circular 1268.

Utah, 1997. The Utah Water Data Book, The Utah Division of Water Resources, Salt Lake City,
Utah, August 1997.

WaterSense, 2006. Personal communications with the U.S. EPA Office of Water. December,
2006.

WaterSense, 2007a. WaterSense Tank-Type High Efficiency Toilet Specification Supporting
Statement. Accessed at: http://www.epa.gov/watersense/docs/het_suppstat508.pdf

WaterSense, 2007b. WaterSense High Efficiency Lavatory Faucet Specification Supporting
Statement. Accessed at: http://www.epa.gov/watersense/docs/faucet_suppstat_final508.pdf

WEF, 1997. Energy Conservation in Wastewater Treatment Facilities. WEF Manual of Practice
No. FD-2, Water Environment Federation, Alexandria, Virginia, 1997.

Western Resource Advocates, 2003. Smart Water. A Comparative Study of Urban Water Use
Across the Southwest. Western Resource Advocates, Boulder, Colorado, December 2003.

Wilkinson, 2000. Methodology for Analysis of the Energy Intensity of California’s Water
Systems. Robert Wilkinson, Environmental Studies Program, University of California, Santa
Barbara, California, January 2000.







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