NREL is a national laboratory of the U.S. Department of Energy, Office of Energy 

Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Contract No. DE-AC36-08GO28308

A Review of Operational Water 

Consumption and Withdrawal 

Factors for Electricity 

Generating Technologies 

Jordan Macknick, Robin Newmark, 

Garvin Heath, and KC Hallett

Technical Report

NREL/TP-6A20-50900

March 2011
NREL is a national laboratory of the U.S. Department of Energy, Office of Energy 

Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

National Renewable Energy Laboratory

1617 Cole Boulevard

Golden, Colorado 80401

303-275-3000 • www.nrel.gov

Contract No. DE-AC36-08GO28308

A Review of Operational Water 

Consumption and Withdrawal 

Factors for Electricity 

Generating Technologies 

Jordan Macknick, Robin Newmark, 

Garvin Heath, and KC Hallett

Prepared under Task No. DOCC.1005

Technical Report

NREL/TP-6A20-50900

March 2011
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Acknowledgments

This work was funded by the U.S. Department of Energy’s (DOE’s) Office of Energy Efficiency 

and Renewable Energy (EERE) and Office of Policy and International Affairs (PI). The authors 

wish to thank Allan Hoffman and Diana Bauer for their support of this work. We are also 

indebted to the following individuals for their thoughtful comments, input, and review of the 

document in its various stages: Kristen Averyt, Western Water Assessment (WWA) and the 

University of Colorado; Stacy Tellinghuisen, Western Resource Advocates; Timothy Diehl, 

U.S. Geological Survey; and Lynn Billman, Elaine Hale, Margaret Mann, Walter Short, and 

Daniel Steinberg, NREL. In addition, we would like to thank the participants in the Water for 

Energy Workshop who provided valuable input, particularly Christina Alvord and Brad Udall, 

WWA and University of Colorado; Mike Hightower and Vince Tidwell, Sandia National 

Laboratories; Curt Brown, U.S. Bureau of Reclamation; Margot Gerritsen, Stanford University; 

Eric Fournier, UC Santa Barbara; Alex Schroeder, Western Governors’ Association; Ashlynn 

Stillwell, University of Texas Austin; Steve Clemmer and John Rogers, Union of Concerned 

Scientists; Andrew Wolfsberg, Los Alamos National Laboratory; and Larry Flowers, NREL. We 

also wish to thank Mary Lukkonen of NREL for her editorial support. 
iv

Executive Summary

This report provides estimates of operational water withdrawal and water consumption factors 

for electricity generating technologies in the United States. Estimates of water factors were 

collected from published primary literature and were not modified except for unit conversions. 

The presented water factors may be useful in modeling and policy analyses where reliable power 

plant level data are not available. Major findings of the report include: 

• The power sector withdraws more water than any other sector in the United States and is 

heavily dependent on available water resources. Changes in water resources may impact 

the reliability of power generation. 

• Water withdrawal and consumption factors vary greatly across and within fuel 

technologies. Water factors show greater agreement when organized according to cooling 

technologies as opposed to fuel technologies. Once-through cooling technologies 

withdraw 10 to 100 times more water per unit of electric generation than recirculating 

cooling technologies; recirculating cooling technologies consume at least twice as much 

water as once-through cooling technologies.

• A transition to a less carbon-intensive electricity sector could result in either an increase 

or decrease in water use, depending on the choice of technologies and cooling systems 

employed. Concentrating solar power (CSP) technologies and coal facilities with carbon 

capture and sequestration (CCS) capabilities have the highest water consumption values 

when using a recirculating cooling system. Non-thermal renewables, such as 

photovoltaics (PV) and wind, have the lowest water consumption factors. 

• Federal datasets on water use in power plants have numerous gaps and methodological 

inconsistencies. Federal agencies are currently coordinating to improve these data. Water 

use factors discussed here are good proxies for use in modeling and policy analyses, at 

least until power plant level data improve.

• Impacts of the power sector on freshwater availability can be reduced by utilizing dry 

cooling or by using non-freshwater sources for cooling. However, these alternatives are 

limited by locally available resources and may have cost and performance penalties. 

Improved power plant data and further studies into the water requirements of energy 

technologies in different climatic regions would facilitate greater resolution in analyses of water 

impacts of future energy and economic scenarios. This report provides the foundation for 

conducting water use impact assessments of the power sector while also identifying gaps in data 

that could guide future research. 
v 

Table of Contents

List of Figures ............................................................................................................................................ vi

List of Tables .............................................................................................................................................. vi

1 Introduction........................................................................................................................................... 1

2 Scope and Methods.............................................................................................................................. 2

3 Data Availability and Gaps .................................................................................................................. 5

4 Results: Water Consumption and Withdrawal Factors .................................................................... 6

5 Discussion........................................................................................................................................... 15

6 Summary ............................................................................................................................................. 17

References................................................................................................................................................. 18
vi 

List of Figures 

Figure 1. Operational water consumption factors for electricity generating technologies ............. 7

Figure 2. Operational water consumption factors for geothermal technologies ............................. 8

Figure 3. Operational water withdrawals for electricity generating technologies .......................... 9

Figure 4. Operational water withdrawal factors for recirculating cooling technologies ...............10

List of Tables

Table 1. Water Consumption Factors for Renewable Technologies (gal/MWh) ......................... 12

Table 2. Water Consumption Factors for Non-renewable Technologies (gal/MWh) .................. 13

Table 3. Water Withdrawal Factors for Electricity Generating Technologies (gal/MWh) .......... 14
1 

1 Introduction

Thermoelectric power use has a significant impact on water resources and the power sector is 

highly dependent on these water resources; the United States Geological Survey (USGS) 

estimated on a national level that 41% of all freshwater withdrawals in the United States in 2005 

were for thermoelectric power operations, primarily for cooling needs [1]. The power sector is 

thus highly vulnerable to changes in water resources, especially those that may result from 

potential climatic changes [2-5]. Increasingly, state agencies in California and New York have 

taken policy actions to address the impacts of power plants’ water use and the environmental 

impacts of their cooling systems [6, 7]. Furthermore, the 2007 drought in the Southeast exposed 

many thermal generators, including Brown’s Ferry nuclear plant, to water-related shut downs 

and curtailments due to unlawfully high discharge temperature and shallow or exposed cooling 

water inlet locations [8]. Effective integrated energy and water policy planning will require 

identifying the individual and cumulative impacts that power plant configurations have on water 

resources and the vulnerabilities of specific power plants to changes in water resources. Various 

studies have attempted to consolidate published estimates of water use impacts of electricity 

generating technologies, resulting in a wide range of technologies and values based on different 

primary sources of literature [9-14]. The goal of this work is to consolidate the various primary 

literature estimates of water use during the generation of electricity by conventional and 

renewable electricity generating technologies in the United States to more completely convey the 

variability and uncertainty associated with water use in electricity generating technologies. 

Individual water use factors, reported in terms of the volume of water used per unit of electrical 

output (gallons per megawatt-hour), are technology and cooling system specific. These water use 

factors can be incorporated into energy-economic models to estimate generation-related water 

use under different projected electricity portfolio scenarios. 
2 

2 Scope and Methods

We evaluate two aspects of water usage: withdrawal and consumption. According to the USGS, 

“withdrawal” is defined as the amount of water removed from the ground or diverted from a 

water source for use, while “consumption” refers to the amount of water that is evaporated, 

transpired, incorporated into products or crops, or otherwise removed from the immediate water 

environment [1]. Both water withdrawal and consumption values are important indicators for 

water managers determining power plant impacts and vulnerabilities associated with water 

resources. 

We consider water withdrawals and consumption for the operational phase only. Operational 

water use in this study includes cleaning, cooling, and other process-related needs that occur 

during electricity generation, such as flue gas desulfurization (FGD) in coal facilities. For the 

vast majority of power generation technologies, most of the water used in the life cycle of the 

plant occurs during the operational phase, with the exception of non-thermal renewable energy 

technologies that do not require cooling systems [9]. In addition, compared to the operational 

phase, data for the water requirements of other phases (such as the fuel cycle) are scarce, are 

subject to greater definitional boundary differences, and have more site-specific differences. 

Also, although the location of the plant is permanent, the locations of the manufacturing or fuel 

sources are not permanent. Given this and the continuous local impacts of power plant water use 

on water resources during the operational phase, we limit this study to a detailed review of only 

the operational water requirements of electricity generating technologies. 

The energy technologies addressed here consist of configurations of concentrating solar power 

(CSP), solar photovoltaic (PV), wind, biopower, geothermal, hydroelectric, nuclear, natural gas, 

and coal technologies. Cooling system technologies considered include wet recirculating 

technologies (evaporative cooling towers), once-through cooling systems (open loop cooling), 

air-cooled condensing (dry cooling), hybrid wet and dry cooling systems (hybrid cooling), and 

pond cooling systems. 

Electricity generating technologies use water for different processes, depending on their 

configuration. Thermal electricity technologies (e.g., CSP, biopower, coal, nuclear, and natural 

gas technologies) generally require water as the working fluid (and as the cooling medium to 

condense steam) as part of the Rankine cycle, the thermodynamic process that drives the steam 

engine [15]. CSP facilities use water for steam cycle processes, for cleaning mirrors or heliostats, 

and for cooling if a cooling tower is used. PV systems require occasional panel washing. Wind 

systems require very little water, if any, for cleaning. Biopower facilities use water for cooling 

and for steam cycle processing. Upstream water needs for growing energy crops are not 

included in this analysis but can be quite substantial (approximately 100 times greater than 

operational cooling system needs) and can vary greatly depending on region, crop, and 

production methods [16-18]. Geothermal technology configurations (e.g., dry steam, binary, and 

flash) can differ greatly in their use of water due to differences in reinjection techniques as well 

as vapor temperature and mass [19]. Enhanced Geothermal Systems (EGS) operate similar to 

geothermal binary technologies yet also require some additional water for hydraulic stimulation 

[19]. Water used in geothermal technologies may come from geothermal fluids, with little to no 

impact on local freshwater sources [20]. Over time, however, some geothermal plant efficiencies 

may decline and may require outside fresh or brackish water sources, and some technologies 
3 

may lower local water tables [19, 21]. Hydroelectric facilities using reservoirs have evaporative 

losses resulting from the dammed water [22, 23]. Nuclear, natural gas, and coal facilities use 

water for cooling and for steam cycle processes. Coal facilities may also use water for FGD. 

Fossil technologies employing carbon capture and storage capabilities will require additional 

process water requirements [12]. 

Estimates of water consumption and withdrawal are displayed irrespective of geographic 

location, as many published data do not specify the location or climatic conditions of the plant. 

The location of a plant, and its corresponding climatic conditions, can affect its overall efficiency 

and thus its water use rate [24-27]. Similar fossil plants utilizing cooling towers may have water 

consumption and withdrawal factors that differ by more than 16%, depending on the location in 

the United States [28]. Similarly, water consumption factors of CSP plants utilizing cooling 

towers may differ by as much as 20% [15]. Inter-annual variations in water intensity are also not 

considered for this review. Withdrawal and consumption factors are often reported in terms of 

annual averages, yet water intensity of facilities may change by as much as 16% as a result of 

diurnal and seasonal variations in temperatures, wind speeds, and humidity levels [28]. Other 

factors that may influence water use intensities of power plants that are not considered here 

include the age of the plant, the thermal efficiency of the plant, the age of the cooling system, 

and the water source [26, 27]. 

Certain aggregations of fuel technology types and cooling system types were made to facilitate 

analyses. Nuclear technologies include pressurized water reactors and boiling water reactors. 

Coal technologies make no distinction between wet, dry, and no FGD. For recirculating cooling 

technologies, no distinction is made between natural draft and mechanical draft cooling tower 

systems. All pond-cooled systems are treated identically. Pond-cooled systems can be operated 

in manners that resemble both recirculating systems and once-through systems as well as in 

hybrids of these technologies [29]. Different configurations and operating practices of pondcooled systems can lead to widely different reported water withdrawal and consumption values. 

No distinction is made between water types, which may include freshwater (surface and 

groundwater), saline water, or municipal waste water. In 2005, 71% of thermoelectric water 

withdrawals were from freshwater sources [1]. Saline withdrawals are primarily concentrated in 

California, Florida, and the coastal Northeast, with the rest of the country relying on freshwater. 

Data sources include published academic literature, state and federal government agency reports, 

non-governmental organizations’ reports, and industry submissions to government agencies for 

permitting procedures. Estimates of national average water use intensity for particular 

technologies, estimates of existing plant operational water use, and estimates derived from 

laboratory experiments were considered equally. Certain sources report ranges of water 

consumption and withdrawal factors in place of specific values. If traceable individual case 

studies form the basis for the range given, the individual values are included as independent 

estimates within the set of estimates that are statistically analyzed. If a range is given and the 

underlying data points are not given, then the midpoint of that range is used for calculating an 

average value, and the high and low extremes are used for determining extreme ranges. This 

method of addressing ranges may lead to a bias toward data sources reporting explicit cases and 

may also underestimate actual water use at facilities, as it was observed that the midpoint of the 

range of extremes are in general less than values reported from individual facilities. This review 

did not alter (except for unit conversion) or audit for accuracy the estimates of water use 
4 

published. Because estimates are used as published, considerable methodological inconsistency 

is inherent, limiting comparability. We report minimum, maximum, and median values for fuel 

technology and cooling system combinations in tables and additionally show 25th and 75th

percentile data in figures. Due to the wide range of values reported from a small number of 

sources, median values may differ significantly from mean values. Upon request, raw data are 

available from the authors.
5 

3 Data Availability and Gaps

Although the power sector is the largest user of water in the nation, national statistics on the 

consumption and withdrawal rates of individual power plants are characterized by 

inconsistencies and scarcity [30]. Power sector water use data on a national level are collected 

by two federal agencies, the USGS and the U.S. Department of Energy’s Energy Information 

Administration (EIA). The USGS reports water withdrawals for thermoelectric power 

production by county and sector every five years; water consumption values for thermoelectric 

power production were last reported for 1995 [31]. These data are collected by state agencies that 

do not always utilize the same methods or definitions in determining water withdrawals [1]. 

EIA provides official energy statistics on an annual basis, and EIA Form 923 reports, among 

other data, annual water withdrawal, discharge, and consumption rates in Schedule 8D, providing 

similar definitions of withdrawal and consumption as the USGS [29]. However, data are not 

entirely comprehensive and have omitted nuclear facilities and some natural gas combined cycle 

technologies [32]. Additionally, the quality of data is also of concern with power plants reporting 

data; many of the power plants report water withdrawal and consumption values that are far 

below or above detailed engineering studies of water use in power plants considered in this 

review. The National Energy Technology Laboratory compiled water use data in their 2007 Coal 

Power Plant DataBase [33]. However, this database is limited by the data availability and 

quality of EIA datasets. No similar public database has been developed for natural gas or 

nuclear generating facilities. 

Detailed engineering studies and more general assessments of water use at individual 

thermoelectric power plants are uneven in their treatment of fuel technologies and cooling 

systems. For example, water consumption data for coal, natural gas, nuclear, and parabolic 

trough CSP facilities using a wet recirculating cooling system are relatively abundant. Fewer 

studies are available addressing water withdrawals for all technologies or water consumption for 

once-through, pond, and dry-cooling systems. Very little data exist for dedicated biomass, 

geothermal, and power tower CSP facilities. 

Additionally, boundary conditions of water use studies are not always clear or consistent; some 

sources only report aggregated operational water usage, whereas other reports include water use 

by individual processes. However, the particular processes included in disaggregated studies may 

not be equivalent; the inclusion of FGD water requirements in coal facilities is one example 

where its explicit or implicit consideration is inconsistent across datasets. Geothermal facilities 

add an additional layer of complexity, as often cooling processes can make use of geothermal 

fluids rather than freshwater; some sources exclude geothermal fluids from calculations whereas 

others include geothermal fluids. Estimates of evaporation from hydropower reservoirs are 

complicated by the multiple uses of reservoirs (e.g., water supply, recreation, and flood control) 

and the different methods of allocating evaporation to electricity production [22, 23]. 

Hydropower estimates are reported according to the allocation methods utilized in the published 

reports, which allocate all reservoir evaporation to power production. 
6 

4 Results: Water Consumption and Withdrawal Factors 

The cooling system employed is often a greater determinant of water usage than the particular 

technology generating electricity, both in terms of water consumption (Figures 1 and 2) and 

water withdrawal (Figures 3 and 4). Once-through cooling technologies withdraw 10 to 100 

times more water per unit of electric generation than cooling tower technologies, yet cooling 

tower technologies consume at least twice as much water as once-through cooling technologies. 

Water consumption for dry cooling at CSP, biopower, and natural gas combined cycle plants is 

an order of magnitude less than for recirculating cooling at each of those types of plants. 
7 

Figure 1. Operational water consumption factors for electricity generating technologies 

IGCC: Integrated gasification combined cycle. CCS: Carbon capture and sequestration. CSP: Concentrating solar power. W

maxima and minima. Upper and lower ends of boxes represent 75th and 25th percentile, respectively. Horizontal lines in bo
8 

Figure 2. Operational water consumption factors for geothermal technologies

EGS: Enhanced geothermal systems. Whisker ends represent maxima and minima. Upper and lower 

ends of boxes represent 75th and 25th percentile, respectively. Horizontal lines in boxes represent 

medians. 
9 

Figure 3. Operational water withdrawals for electricity generating technologies

IGCC: Integrated gasification combined cycle. CCS: carbon capture and storage. Whisker ends represent maxima and minima. Upper and lower 

ends of boxes represent 75th and 25th percentile, respectively. Horizontal lines in boxes represent medians. Recirculating cooling withdrawal 

values are also shown in Figure 4.
10 

Figure 4. Operational water withdrawal factors for recirculating cooling technologies

IGCC: Integrated gasification combined cycle. CCS: carbon capture and storage. Whisker ends 

represent maxima and minima. Upper and lower ends of boxes represent 75th and 25th percentile, 

respectively. Horizontal lines in boxes represent medians. 
11 

Water consumption factors for renewable (Table 1) and non-renewable (Table 2) electricity 

generating technologies vary substantially within and across technology categories. The highest 

water consumption factors for all technologies result from the use of evaporative cooling towers. 

With the exception of hydropower, pulverized coal with carbon capture and CSP technologies 

utilizing a cooling tower represent the upper bound of water consumption, at approximately 

1,000 gal/MWh of electricity production. The lowest operational water consumption factors 

result from wind energy, PV, and CSP Stirling solar technologies and natural gas combined cycle 

facilities that employ dry cooling technologies. Water withdrawal factors for electricity 

generating technologies show a similar variability within and across technology categories 

(Table 3). The highest water withdrawal values result from nuclear technologies, whereas the 

smallest withdrawal values are for non-thermal renewable technologies. Consistent with 

literature, withdrawal factors for CSP, wind, geothermal, and PV systems are assumed to be 

equivalent to consumption factors. 
12 

Table 1. Water Consumption Factors for Renewable Technologies (gal/MWh) 

Fuel Type Cooling Technology Median Min Max n S

PV N/A Utility Scale PV 26 0 33 3 [10

Wind N/A Wind Turbine 0 0 1 2 [

CSP 

Tower 

Trough 865 725 1,057 17 [10, 

Power Tower 786 740 860 4 [3

Fresnel 1,000 1,000 1,000 1 

Dry Trough 78 43 79 10 [3

Power Tower 26 26 26 1 

Hybrid Trough 338 105 345 3 [

Power Tower 170 90 250 2 

N/A Stirling 5 4 6 2 [

Biopower 

Tower Steam 553 480 965 4 

Biogas 235 235 235 1 

Once-through Steam 300 300 300 1 

Pond Steam 390 300 480 1 

Dry Biogas 35 35 35 1 

Geothermal1

Tower 

Dry Steam 1,796 1,796 1,796 1 

Flash (freshwater) 10 5 19 3 [19

Flash (geothermal fluid) 2,583 2,067 3,100 2 

Binary 3,600 1,700 3,963 3 [10

EGS 4,784 2,885 5,147 4 [10, 

Dry 

Flash 0 0 0 1 

Binary 135 0 270 2 [

EGS 850 300 1,778 2 [

Hybrid Binary 221 74 368 1 

EGS 1,406 813 1,999 2 [

Hydropower N/A Aggregated in-stream and reservoir 4,491 1,425 18,000 3 [

1 Most geothermal facilities can use geothermal fluids or freshwater for cooling. 
13 

Table 2. Water Consumption Factors for Non-renewable Technologies (gal/MWh)

 

Fuel Type Cooling Technology Median Min Max n Sources 

Nuclear

Tower Generic 672 581 845 6 [10, 14, 27, 50, 57] 

Oncethrough Generic 269 100 400 4 [27, 50, 57, 58] 

Pond Generic 610 560 720 2 [27, 50] 

Natural 

Gas

Tower

Combined Cycle 198 130 300 5 [13, 34, 50, 57, 59] 

Steam 826 662 1,170 4 [10, 14, 49, 60] 

Combined Cycle with CCS 378 378 378 1 [59] 

Oncethrough

Combined Cycle 100 20 100 3 [50, 57, 60] 

Steam 240 95 291 2 [10, 49] 

Pond Combined Cycle 240 240 240 1 [57] 

Dry Combined Cycle 2 0 4 2 [50, 57] 

Inlet Steam 340 80 600 1 [49] 

Coal

Tower

Generic 687 480 1,100 5 [10, 14, 27, 50, 58] 

Subcritical 471 394 664 6 [13, 57, 59, 61] 

Supercritical 493 458 594 6 [13, 57, 59, 61] 

IGCC 372 318 439 7 [13, 59] 

Subcritical with CCS 942 942 942 1 [59] 

Supercritical with CCS 846 846 846 1 [59] 

IGCC with CCS 540 522 558 3 [59] 

Oncethrough

Generic 250 100 317 4 [10, 27, 50, 58] 

Subcritical 113 71 138 3 [57] 

Supercritical 103 64 124 3 [57] 

Pond

Generic 545 300 700 2 [27, 50] 

Subcritical 779 737 804 3 [57] 

Supercritical 42 4 64 3 [57] 
14 

Table 3. Water Withdrawal Factors for Electricity Generating Technologies (gal/MWh)

Fuel Type Cooling Technology Median Min Max n Sources 

Nuclear

Tower Generic 1,101 800 2,600 3 [27, 50, 57] 

Once-through Generic 44,350 25,000 60,000 4 [27, 50, 57, 58] 

Pond Generic 7,050 500 13,000 2 [27, 50] 

Natural 

Gas

Tower

Combined Cycle 253 150 283 6 [12, 13, 50, 57, 59] 

Steam 1,203 950 1,460 2 [49, 60] 

Combined Cycle with 

CCS 496 487 506 2 [12, 59] 

Once-through Combined Cycle 11,380 7,500 20,000 2 [50, 57] 

Steam 35,000 10,000 60,000 1 [49] 

Pond Combined Cycle 5,950 5,950 5,950 1 [57] 

Dry Combined Cycle 2 0 4 2 [50, 57] 

Inlet Steam 425 100 750 1 [49] 

Coal

Tower

Generic 1,005 500 1,200 4 [27, 35, 50, 58] 

Subcritical 531 463 678 7 [12, 13, 57, 59, 61] 

Supercritical 609 582 669 7 [12, 13, 57, 59, 61] 

IGCC 390 358 605 11 [12, 13, 35, 59] 

Subcritical with CCS 1,277 1,224 1,329 2 [12, 59] 

Supercritical with CCS 1,123 1,098 1,148 2 [12, 59] 

IGCC with CCS 586 479 678 6 [12, 59] 

Once-through

Generic 36,350 20,000 50,000 4 [11, 27, 50, 58] 

Subcritical 27,088 27,046 27,113 3 [57] 

Supercritical 22,590 22,551 22,611 3 [57] 

Pond

Generic 12,225 300 24,000 2 [27, 50] 

Subcritical 17,914 17,859 17,927 3 [57] 

Supercritical 15,046 14,996 15,057 3 [57] 

Biopower

Tower Steam 878 500 1,460 2 [49] 

Once-through Steam 35,000 20,000 50,000 1 [50] 

Pond Steam 450 300 600 1 [50] 
15 

5 Discussion 

Despite methodological differences in data, general trends can be observed and broad 

conclusions can be drawn from the breadth of data collected. A transition to a less carbonintensive electricity sector could result in either an increase or decrease in water consumption per 

unit of electricity generated, depending on the choice of technologies and cooling systems 

employed. Non-thermal renewable technologies, such as wind and PV systems, consume 

minimal amounts of water per unit of generation. However, the highest water consumption 

factors considered in this study, excluding geothermal and hydroelectric facilities, which can 

have high water intensities but also have important caveats, are low-carbon emitting technologies 

that utilize cooling towers: pulverized coal with carbon capture technologies and CSP systems. 

Decisions affecting the power sector’s impact on the climate may need to include water 

considerations to avoid negative unintended environmental consequences on water resources. 

This can be addressed by integrated energy and water policy planning, as the availability of 

water in certain jurisdictions may limit the penetration of these technologies and cooling system 

configurations. 

Freshwater use impacts can be reduced by utilizing dry cooling or by using non-freshwater 

sources as a cooling medium. Initial work suggests that the performance penalty for CSP 

facilities switching from wet cooling to dry cooling results in an annual reduction in output of 

2%–5% and an increase in the levelized cost of producing energy of 3%–8%, depending on local 

climatic conditions [15]. Using national averages, the annual performance penalty for switching 

from wet cooling to dry cooling for nuclear plants is 6.8%, combined cycle plants 1.7%, and 

other fossil plants (including coal and natural gas steam plants) 6.9% [62]. Further efforts are 

needed to evaluate performance and cost penalties associated with utilizing dry or hybrid cooling 

systems for fossil fuel facilities using carbon capture technologies. Utilizing reclaimed water, 

such as municipal wastewater, is another approach that could lessen the impact of the power 

sector on freshwater resources and wastewater treatment facilities. The legal and physical 

availability of municipal wastewater, especially in rural areas, may be a limiting factor to its 

widespread usage, and the cost and performance penalties of utilizing such sources must be 

investigated further [63]. 

The choice of cooling system may play an important role in the development of our future 

electricity mix. Differences between cooling systems can have substantial environmental impacts 

on local water resources [64-66]. Employing wet cooling technologies (i.e., once-through and 

cooling tower technologies) imposes an inherent tradeoff between relatively high water 

consumption and relatively high water withdrawals, which has important implications for 

regional cooling system policies and regulations. A reduction in withdrawals (but a 

corresponding increase in consumption) may benefit a watershed that has an abundance of water 

but may lead to concerns in an area that is already lacking water. A shift away from, for 

example, once-through cooling systems in coastal areas that withdraw saline water, to inland 

recirculating systems such as cooling towers that primarily consume freshwater, will impact 

watersheds and water availability differently depending on local conditions. The use of 

alternative cooling technologies may serve as an energy security benefit for utilities and 

communities, given uncertainties in future scenarios of water availability and expected 

vulnerabilities for power plants [4, 5]. Reduced levels in bodies of water, or substantial increases 

in the temperature of these bodies of water, may require thermal power plants to run at lower 
16 

capacities or to shut down completely, as was seen in France in 2003 [67]. Utilizing dry cooling 

or non-freshwater sources avoids some of the risks associated with these drought and climate 

change scenarios. 

Accurate estimates of water use in individual power plants, and the effect of this water use on a 

regional scale, will be elusive until more studies are conducted for the variety of technologies 

and cooling systems currently in operation along with those expected to be developed and 

deployed. Furthermore, calibration of these values on national and regional scales will remain 

challenging until methods for collecting and evaluating data by federal agencies has improved. 

Nonetheless, certain conclusions regarding the overall impact power plants have on water 

resources can be drawn on regional levels from existing water use data. 

Further studies with consistent boundary conditions and methods are necessary to develop water 

consumption and withdrawal estimates for certain technologies and cooling systems to fully 

understand reasons for variations in data that are not attributable to climatic factors or technology 

vintages. To better understand how cooling system and technology system decisions will be 

made in the future, analyses using energy-economic models will require improved data on water 

availability and regional water use factors. Existing data collected from federal agencies are 

currently inconsistent and incomplete [30]. However, in 2009, the U.S. Government 

Accountability Office released a report calling for improvements in federal agency water data 

collection in power plants; EIA is currently working with the USGS and other federal agencies to 

improve the scope and quality of its data collection [30]. Such efforts should improve the 

availability of power plant specific data and the ability to calibrate model estimates. 
17 

6 Summary

We reviewed primary literature for data on water withdrawal and consumption factors for 

electricity generation in the United States and have consolidated them in this study. These 

detailed water consumption and withdrawal factors can be utilized in energy-economic and 

transmission planning models to better understand the regional and national impacts on water 

resources for various electricity future scenarios and can inform policy analysis at a national and 

local level. Improved power plant data gathered on a regional level and further studies into the 

water requirements of existing and emerging technologies (such as carbon capture technologies) 

are necessary to assess the water impacts of a developing decarbonizing economy in more detail. 
18 

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F1147-E(10/2008) 

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A Review of Operational Water Consumption and Withdrawal 

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Various studies have attempted to consolidate published estimates of water use impacts of electricity generating 

technologies, resulting in a wide range of technologies and values based on different primary sources of literature. 

The goal of this work is to consolidate the various primary literature estimates of water use during the generation of 

electricity by conventional and renewable electricity generating technologies in the United States to more completely 

convey the variability and uncertainty associated with water use in electricity generating technologies. 

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water consumption; water withdrawal; electricity generating technologies; geothermal; thermoelectric power; cooling 

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