DOE/NETL-400/2007/1304 

September 24, 2007 

Estimating Freshwater Needs to Meet Future 

Thermoelectric Generation Requirements 

2007 Update 
Disclaimer

This report was prepared as an account of work sponsored by an agency of 

the United States Government. Neither the United States Government nor 

any agency thereof, nor any of their employees, makes any warranty, 

express or implied, or assumes any legal liability or responsibility for the 

accuracy, completeness, or usefulness of any information, apparatus, 

product, or process disclosed, or represents that its use would not infringe 

privately owned rights. Reference therein to any specific commercial 

product, process, or service by trade name, trademark, manufacturer, or 

otherwise does not necessarily constitute or imply its endorsement, 

recommendation, or favoring by the United States Government or any 

agency thereof. The views and opinions of authors expressed therein do 

not necessarily state or reflect those of the United States Government or 

any agency thereof. 
Estimating Freshwater Needs to Meet Future 

Thermoelectric Generation Requirements 

2007 Update 

DOE/NETL-400/2007/1304 

September 24, 2007 

NETL Contact: 

Erik Shuster 

Office of Systems Analyses and Planning 

Prepared by: 

Erik Shuster – NETL/DOE 

Andrea McNemar - NETL/DOE 

Gary J. Stiegel, Jr. - Research and Development Solutions, LLC 

James Murphy - Research and Development Solutions, LLC 

National Energy Technology Laboratory 

www.netl.doe.gov 

Table of Contents 

Executive Summary.......................................................................................................... 1 

Introduction....................................................................................................................... 8 

Energy-Water Issues...................................................................................................... 9 

Water Availability ....................................................................................................... 9 

NETL Energy-Water R&D Program .......................................................................... 10 

Previous Water Needs Analysis................................................................................... 11 

Water Requirements for Thermoelectric Generation................................................. 11 

Projections of Thermoelectric Capacity and Generation............................................ 14 

Assumptions and Methodology...................................................................................... 18 

Step 1: Develop model plants....................................................................................... 19 

Fresh versus Saline Water........................................................................................ 19 

Step 2: Calculate water withdrawal and consumption factors................................... 20 

Evaporative Loss Associated with Once-Through Cooling Systems ........................ 20 

Subcritical versus Supercritical Boiler for New Coal-Fired Power Plants ............. 20 

Flue Gas Desulfurization Systems for Retrofit and New Coal-Fired Power Plants. 21 

Integrated Gasification Combined Cycle Plants...................................................... 21 

Natural Gas Combined Cycle Plants........................................................................ 21 

Step 3: Quality Control and Model Validation ........................................................... 21 

Step 4: Develop Future Cases...................................................................................... 23 

Step 5: Calculate regional withdrawal and consumption to 2030 ............................. 25 

Water Use for CO2 Capture Equipped Coal-Fired Power Plants.............................. 25 

Results.............................................................................................................................. 27 

Thermoelectric Generation – National Level Summary ............................................ 27 

Thermoelectric Generation - National Level Results by Case ................................... 29 

Thermoelectric Generation – Regional Results.......................................................... 38 

Conventional Coal-Fired Generation - National Level Results by Case................... 49 

Conventional Coal-Fired Generation – Regional Results ......................................... 51 

Carbon Capture Deployment Analysis........................................................................ 57 

Comparison of 2006 & 2007 Study Projections.......................................................... 62 

Conclusions...................................................................................................................... 64 

Appendix A................................................................................................................... A-1 

Appendix B................................................................................................................... B-1 

Appendix C................................................................................................................... C-1 

Appendix D.................................................................................................................... D-1 

Appendix E .....................................................................................................................E-1 

Appendix F .....................................................................................................................F-1 

Appendix G.................................................................................................................... G-1 

References...................................................................................................................... R-1 

Freshwater Needs for Thermoelectric Generation, September 2007 

1 

Executive Summary 

Growing concerns about freshwater availability must be reconciled with growing demand 

for power if the United States is to maintain economic growth and current standards of 

living. Thermoelectric generating capacity is expected to increase by nearly 22% 

between 2005 and 2030, based on the Energy Information Administration’s (EIA) Annual 

Energy Outlook 2007 (AEO 2007) projections.1

 Two previous water needs analyses have 

been conducted by the Department of Energy’s National Energy Technology Laboratory 

(DOE/NETL); one in 2004 and the other in 2006. The 2004 report suggested that 

national freshwater withdrawals may increase slightly or decline depending on 

assumptions made, while freshwater consumption will likely increase dramatically.2

 

However, regional water impacts can be significantly different than national data 

averages might suggest. To characterize the significance of the regional impacts on water 

use, the August 2006 report compared regional electricity demand and capacity forecasts 

from AEO 2006 with representative water withdrawal and consumption estimates to 

identify regions where water issues could become acute. 

This report is an update to the August 2006 report using projection from EIA’s AEO 

2007 forecast. With increased “climate change” concerns and the possible future policies 

regarding carbon capture and sequestration (CCS), this report also examines the impact 

that CCS technologies would have on water withdrawal and consumption. Future 

freshwater withdrawal and consumption requirements for the U.S. thermoelectric 

generation sector were estimated for five cases, using AEO 2007 regional projections for 

capacity additions and retirements:a

Case 1 – Additions and retirements are proportional to current water source and type of 

cooling system. 

Case 2 – All additions use freshwater and wet recirculating cooling, while retirements are 

proportional to current water source and cooling system. 

Case 3 – 90% of additions use freshwater and wet recirculating cooling, and 10% of 

additions use saline water and once-through cooling, while retirements are proportional to 

current water source and cooling system. 

Case 4 – 25% of additions use dry cooling and 75% of additions use freshwater and wet 

recirculating cooling. Retirements are proportional to current water source and cooling 

system. 

Case 5 – Additions use freshwater and wet recirculating cooling, while retirements are 

proportional to current water source and cooling system. Five percent of existing 

freshwater once-through cooling capacity is retrofitted with wet recirculating cooling 

every five years starting in 2010. 

Summary results for the five cases, on a national basis, are presented in Table ES-1. For 

Cases 2 though 5, withdrawal is expected to decline, and consumption for all 5 cases is 

expected to increase. These results are consistent with current and anticipated regulations 

and industry practice, which favor the use of freshwater recirculating cooling systems 

 

a

 See Table 6 in the body of the report for a description of the rationale behind each of these cases and their 

assumptions. 
Freshwater Needs for Thermoelectric Generation, September 2007 

2 

that have lower withdrawal requirements, but higher consumption requirements, than 

once-through cooling systems. Case 5 provides the most extreme water consumption 

impacts. Converting a significant share of existing once-through freshwater power plants 

to recirculating freshwater plants significantly reduces water withdrawal, but significantly 

increases water consumption. Case 4 indicates that dry cooling could have a significant 

impact on water consumption; compared to Cases 1-3, which have an average 

consumption of 8.2 BGD, Case 4 results in a 4% decline, equivalent to more than 100 

billion gallons per year. 

Table ES-1 - Thermoelectric Water Impacts, National Results 

Freshwater withdrawal or consumption (BGD) 

2005 2010 2015 2020 2025 2030 

Withdrawal 149.0 152.3 147.0 153.8 157.5 157.9 Case 1 

Consumption 6.1 6.3 6.6 7.0 7.5 7.9 

Withdrawal 149.0 149.2 143.4 144.1 144.4 143.8 Case 2 

Consumption 6.1 6.3 6.7 7.2 7.7 8.2 

Withdrawal 149.0 149.2 143.4 144.0 144.2 143.6 Case 3 

Consumption 6.1 6.3 6.6 7.2 7.6 8.1 

Withdrawal 149.0 149.0 143.1 143.5 143.4 142.7 Case 4 

Consumption 6.1 6.3 6.6 7.0 7.4 7.8 

Withdrawal 149.0 143.3 131.6 127.2 122.6 117.5 Case 5 

Consumption 6.1 6.5 7.0 7.8 8.4 9.1 

Each of the cases used different assumptions (see Table 6 for rationale behind each case 

and their assumptions). Due to the differences in assumptions, none of the cases can 

truly be considered a baseline for comparison with other cases. However, the year 2005 

can be used as a baseline against which to measure projected future withdrawal and 

consumption. As seen in the 2005 column of Table ES-1, the 2005 withdrawal and 

consumption values for each case are the same. Using this baseline, Table ES-2 was 

generated to show the percent change from the 2005 baseline to each of the future years. 

The negative values in Table ES-2 for withdrawal indicate decreased withdrawal while 

the positive consumption values indicate increasing consumption over time. 

Table ES-2 – Percent Change from 2005 Baseline, National Results 

Percent change from 2005 baseline 

2010 2015 2020 2025 2030 

Withdrawal 2.2 -1.3 3.2 5.7 6.0 Case 1 

Consumption 4.1 8.8 16.0 23.0 30.1 

Withdrawal 0.1 -3.7 -3.3 -3.1 -3.5 Case 2 

Consumption 4.8 10.2 19.5 27.7 35.7 

Withdrawal 0.1 -3.8 -3.3 -3.2 -3.6 Case 3 

Consumption 4.5 9.7 18.3 25.8 33.5 

Withdrawal 0.0 -4.0 -3.7 -3.7 -4.3 Case 4 

Consumption 4.1 8.9 16.3 22.3 28.4 

Withdrawal -3.8 -11.7 -14.6 -17.7 -21.2 Case 5 

Consumption 7.6 16.0 28.1 38.9 49.5 
Freshwater Needs for Thermoelectric Generation, September 2007 

3 

The regional component of the 2007 water needs analysis revealed some significant 

differences from the national averages. For example, consider Case 2, which represents a 

plausible future cooling system scenario. The national percent changes in Table ES-2 

indicate that water withdrawal will fall by 3.5% and that water consumption will rise by 

35.7% between 2005 and 2030. As shown in Figure ES-1 and Figure ES-2 on a regional 

basis, however, water withdrawal ranges from a 42% increase in the Northwest region to 

a 24% decline in Rocky Mountain/desert southwest region; and while freshwater 

consumption increases in all regions, the biggest gains come in California (274%), 

Florida (250%), New York (396%), and (85%) for both the Northwest and Rocky 

Mountain/desert southwest regions. 

Figure ES-1 – Average Daily Regional Freshwater Withdrawal for Thermoelectric Power Generation 

– Case 2 Case

-10

0

10

20

30

40

50

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawal, 2005 Incremental Water Withdrawal, 2005 - 2030
Freshwater Needs for Thermoelectric Generation, September 2007 

4 

Figure ES-2 - Average Daily Regional Freshwater Consumption for Thermoelectric Power 

Generation – Case 2 

0

1

2

3

4

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030

The regional results reflect recent U.S. population shifts. Regions with strong population 

growth, such as the southeast and southwest, exhibit high growth in water consumption 

requirements, while regions with minimal to modest population growth, such as the 

Midwest and Mid-Atlantic, exhibit modest growth in water consumption requirements. 

Specific to coal-fired generation, the analysis projects that by 2030, average daily 

national freshwater withdrawals may decrease to 76.9 BGD or increase to 102.7 BGD 

from a baseline level of 92.3 BGD, depending upon case assumptions. The 2005 baseline 

coal-fired plant withdrawal represents 62% of the total thermoelectric plant withdrawal. 

Average daily national freshwater consumption resulting from U.S. coal-fired power 

generation could reach 3.5 BGD to 4.0 BGD from a baseline level of 2.4 BGD, 

depending upon case assumptions. The 2005 baseline coal-fired plant consumption 

represents 39% of the total thermoelectric plant consumption. Case 2, coal-fired, 

regional water withdrawal and consumption are illustrated in Figures ES-3 and ES-4 

respectively. 
Freshwater Needs for Thermoelectric Generation, September 2007 

5 

Figure ES-3 – Average Daily Regional Freshwater Withdrawal for Coal-Fired Power Generation – 

Case 2 

-5

0

5

10

15

20

25

30

35

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawl, 2005 Incremental Water Withdraw, 2005 - 2030

Figure ES-4 - Average Daily Regional Freshwater Consumption for Coal-Fired Power Generation – 

Case 2 

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030

This analysis and accompanying report were completed to estimate future freshwater 

needs both for coal-fired generation and for total thermoelectric generation. The results 
Freshwater Needs for Thermoelectric Generation, September 2007 

6 

from this report will be used as a base forecast against which to compare 

accomplishments in freshwater withdrawal and consumption reductions. Additionally, 

report results will be used to better understand the regional impacts of constrained water 

resources. 

For the carbon capture deployment water use section of the analysis, it was assumed that 

carbon mitigation policies will be put in place in the near future. The assumed outcome 

in 2030 of those policies would be that all PC plants with scrubbers and IGCC plants 

would employ carbon capture technologies. This includes all new additions and the 

retrofitting of existing PC plants. This analysis follows the EIA AEO 2007 forecast and 

assumes the generation mix would not change under such a climate control scenario. 

Though it is recognized that such a policy regarding climate control could impact fossilfueled power generation, this analysis provides an upper boundary of the estimated 

additional water usage for carbon capture. 

Three scenarios regarding the additional capacity needed to make up for the “parasitic” 

power loss of the carbon capture retrofits were evaluated. Scenario 1 is the 

“conservative” scenario and only accounts for the increased water requirements for the 

carbon capture technologies used for the retrofits and new builds and does not account for 

the 72.7 GW of reduced capacity due to the retrofits. Scenario 2 builds off of Scenario 1 

and assumes that the additional capacity needed to make up for the parasitic loss of the 

retrofits are supplemented by 72.7 GW of new IGCC plants with recirculating cooling 

and include carbon capture technologies. Scenario 3 is similar to Scenario 2 except 

instead of IGCC plants making up the parasitic loss, supercrictical PC plants are used. 

The projected results for PC plants with scrubbers and IGCC plants with 90% CO2

capture for the year 2030 show an increase in water withdrawal and consumption. 

Figure ES-5 shows the additional amount of water withdrawal for each Case and 

Scenario if all forecasted PC plants with scrubbers and IGCC plants were to deploy 

carbon capture technologies compared to no carbon capture deployment across all 

thermoelectric generation for the projected year 2030. For example, the bar for Case 2 in 

Figure ES-5 shows that in 2030, 143.8 BGD of water withdrawal is projected for all 

thermoelectric plants without carbon capture deployment. By deploying carbon capture 

technologies to the scrubbed coal-fired fleet and all new builds, an additional 4.1 BGD 

would be required under Scenario 1, resulting in a total of 147.9 BGD. If Scenario 2 is 

applied, 0.7 BGD would be added to Scenario 1, resulting in a total of 148.6 BGD. 

Scenario 3 would add 1.9 BGD to Scenario 1 resulting in a total of 149.8 BGD 

withdrawal. 
Freshwater Needs for Thermoelectric Generation, September 2007 

7 

Figure ES-5 - Thermoelectric Generation with Additional Water Withdrawal for PC and IGCC 

Carbon Capture Deployment for Year 2030 

0

40

80

120

160

200

Water Withdrawal 

(BGD)

12345

Case

Scenario 3

Scenario 2

Scenario 1

All Non-Capture

Thermoelectric Plants

Figure ES-6 shows the additional amount of water consumption for each Case and 

Scenario if all of the forecasted PC with scrubbers and IGCC plants were to deploy 

carbon capture technologies compared to all thermoelectric plants without carbon capture 

technologies. The bar for Case 2 in Figure ES-6 shows that in 2030, 8.2 BGD of water 

consumption is projected for all thermoelectric plants without carbon capture 

deployment. By deploying carbon capture technologies to the scrubbed coal-fired fleet 

and all new builds, an additional 2.9 BGD would be required under Scenario 1, resulting 

in a total of 11.1 BGD. If Scenario 2 is applied, 0.6 BGD would be added to Scenario 1, 

resulting in a total of 11.7 BGD. Scenario 3 would add 1.4 BGD to Scenario 1 resulting 

in a total water consumption of 12.5 BGD for Scenario 3. Since recirculating cooling 

systems are used in all three scenarios, additional water withdrawal is lower relative to 

water consumption. 
Freshwater Needs for Thermoelectric Generation, September 2007 

8 

Figure ES-6 - Thermoelectric Generation with Additional Water Consumption for PC and IGCC 

Carbon Capture Deployment for Year 2030 

0

2

4

6

8

10

12

14

Water Consumption 

(BGD)

12345

Case

Scenario 3

Scenario 2

Scenario 1

All Non-Capture

Thermoelectric Plants

Introduction 

The purpose of this report is to estimate future freshwater needs for thermoelectric power 

generation. Thermoelectric power plants – coal, oil, natural gas, and nuclear fueled 

power generators using a steam turbine based on the Rankine thermodynamic cycle – 

require significant quantities of water for generating electrical energy.b For example, a 

500-MW coal-fired power plant uses over 12 million gallons per hour of water for 

cooling steam turbine exhaust.3,c The water required for thermoelectric plants is 

withdrawn primarily from large volume sources, such as lakes, rivers, oceans, and 

underground aquifers. While both freshwater (approximately 70%) and saline water 

(approximately 30%) are currently used for thermoelectric generation, this report focuses 

on freshwater because freshwater sources are becoming increasingly strained.4

 Water 

consumption is used to describe the loss of that water, typically through evaporation into 

the air. The United States Geological Survey (USGS) estimated that thermoelectric 

generation accounted for approximately 39% of freshwater withdrawals, ranking only 

slightly behind agricultural irrigation as the largest source of freshwater withdrawals in 

the United States in 2000.4

 However, the corresponding water consumption associated 

with thermoelectric generation accounted for only 2.5% of total U.S. freshwater 

consumption in 1995.5 As U.S. population and associated economic development 

continues to expand, the demand for electricity will increase. The EIA’s latest forecast 

estimates U.S. thermoelectric generating capacity will grow from approximately 709 GW 

in 2005 to 862 GW in 2030.6

 As such, thermoelectric power plants may increasingly 

compete for freshwater with other sectors such as domestic, commercial, agricultural, 

 

b

 Natural gas- and oil-fired combustion turbines are not sources of thermoelectric generation. 

c

 Most of today’s power plants use water as the cooling medium and the amount of water required to 

condense the steam turbine exhaust is similar whether an open-loop or closed-loop cooling system is used 

depending on design conditions. Open-loop cooling systems continuously withdraw water from a local 

water source, and return the same quantity of water to the source. Closed-loop cooling systems circulate a 

similar total volume of water as open-loop systems for a given plant size, but only withdraw a limited 

amount of water to replace evaporative loss and blowdown. Additional information on power plant water 

requirements can be found in the Water Requirements for Thermoelectric Generation section of this report. 
Freshwater Needs for Thermoelectric Generation, September 2007 

9 

industrial, and in-stream use – particularly in regions of the country with limited 

freshwater supplies. In addition, current and future water-related environmental 

regulations and requirements will also challenge the operation of existing power plants 

and the permitting of new thermoelectric generation projects. 

Energy-Water Issues 

At the nexus of water and energy lies a wide variety of societal issues, policy and 

regulatory debate, environmental questions, technological challenges, and economic 

concerns. Water is emerging as a significant factor in economic development activities. 

Planning efforts must consider the availability and quality of water resources in a given 

locality or region to ensure that supplies are available to accommodate existing and future 

water consumers over the long term. Failure to do so can result in stunted growth, 

economic flight, inequitable development, and even open conflict. In order for the power 

industry to be ecologically responsible, technologically ready, and economically stable, 

advanced research is imperative. Energy-water issues have become increasingly visible 

in recent years, with a variety of concerns on the mind of industry, regulators, Congress, 

DOE, and the general public. A sampling of these issues includes the passing of the 

Energy Policy Act of 2005; repeated introduction of the Energy-Water Efficiency and 

Supply Technology Bill; increasingly severe regional drought conditions across the 

country; additional difficulty siting new power generating facilities in arid regions; and 

further media attention and public concern over water availability and supply. The 

following is a brief summary of some of the technical, regulatory, and political issues that 

help explain the importance of water to thermoelectric generation. Additional 

background information on energy-water issues is presented in Appendix A. 

Water Availability 

Water shortages, potentially the greatest challenge to face all sectors of the United States 

in the 21st century, will be an especially difficult issue for thermoelectric generators due 

to the large amount of cooling water required for power generation. According to a GAO 

2003 report7

, national water availability has not been comprehensively assessed in 25 

years, thus water availability on a national level is ultimately unknown. However, as the 

report goes on to say, current trends indicate that demands on the nation’s supplies are 

growing while the nation’s capacity to store surface-water is increasingly more limited 

and ground-water is being depleted. 

Water availability issues are intensified by the fact that population increases are occurring 

in water-stressed areas. Figure 1 shows the percent change in population by state from 

1990 to 2000 and Figure 2 displays mean annual precipitation from 1890 to 2002. 

Comparison of the figures shows that areas where precipitation is low, especially in the 

southwest, are also areas of greatest population growth. 
Freshwater Needs for Thermoelectric Generation, September 2007 

10 

Figure 1 - Percent Change in Population by State: 1990 to 20008

Figure 2 - Mean Annual Precipitation, 1890 to 20029,10

NETL Energy-Water R&D Program 

The U.S. Department of Energy, Office of Fossil Energy’s National Energy Technology 

Laboratory (DOE/NETL) is carrying out a comprehensive, integrated research and 

development (R&D) effort to enhance the efficiency and environmental performance of 

the existing fleet of coal-fired power plants, which represent more than 300 gigawatts 

(GW) of generating capacity, and apply novel concepts to advanced power systems. The 

program goal is to ensure that technologies are available for deployment by 2015 that can 
Freshwater Needs for Thermoelectric Generation, September 2007 

11 

reduce power plant freshwater withdrawal and consumption while minimizing the 

impacts of power plant operation on water quality. To achieve this goal, the energywater interface portion of the Innovations for Existing Plants (IEP) program conducts 

research in four areas: Non-Traditional Sources of Process and Cooling Water; 

Innovative Water Reuse and Recovery; Advanced Cooling Technology; and Advanced 

Water Treatment and Detection Technology. The portfolio of energy-water nexus 

technology R&D projects encompasses laboratory studies, modeling, and pre-commercial 

demonstration full-scale testing. Project success is intimately tied to key collaborations 

and partnerships with industry, federal, state, and local agencies, and the academic and 

research communities. This water needs analysis was conducted in support of the IEP 

energy-water R&D activity. 

Previous Water Needs Analysis 

In 2004, NETL conducted a similar water needs analysis to estimate how thermoelectric 

power plants will impact national freshwater resources through 2025.2

 Using the EIA 

2004 Annual Energy Outlook’s reference case forecast for electricity generating capacity, 

future freshwater requirements for both total and coal-based thermoelectric generation 

were estimated and compared to current and past water use by the power sector. In 2006, 

NETL developed a new water analysis which used a different methodology and different 

cases. The comparisons of the 2004 and 2006 studies are described in more detail in the 

August 2006 Estimating Freshwater Needs to Meet Future Thermoelectric Generation 

Requirements study. This water analysis utilizes the same methodology as the August 

2006 report and uses AEO 2007 data. 

Water Requirements for Thermoelectric Generation 

A significant quantity of water is required for thermoelectric power plants to support 

electricity generation. The largest demand for water in thermoelectric plants is cooling 

water for condensing steam. Thermoelectric generation relies on a fuel source (fossil, 

nuclear, or biomass) to heat water to steam that is used to drive a turbine-generator. 

Steam exhausted from the turbine is condensed and recycled to a steam generator or 

boiler. The steam condensation typically occurs in a shell-and-tube heat exchanger 

known as a condenser. The steam is condensed on the shell side by the flow of cooling 

water through tube bundles located within the condenser. Cooling water mass flow rates 

of greater than 50 times the steam mass flow rate are necessary depending on the 

allowable temperature rise of the cooling water – typically 15-25oF. The design and 

operating parameters of the cooling system are critically important to overall power 

generation efficiency. At higher condenser cooling water inlet temperatures, the steam 

condensate temperature is higher and subsequently turbine backpressure is higher. The 

turbine backpressure is inversely related to power generation efficiency: the higher the 

turbine backpressure, the lower the power generation efficiency. 

There are three general types of cooling system designs used for thermoelectric power 

plants: once-through, wet recirculating, and dry. In once-through systems, the cooling 

water is withdrawn from a local body of water such as a lake, river, or ocean and the 

warm cooling water is subsequently discharged back to the same water body after passing 
Freshwater Needs for Thermoelectric Generation, September 2007 

12 

through the surface condenser. As a result, plants equipped with once-through cooling 

water systems have relatively high water withdrawal, but low water consumption. 

There are two primary technologies used to support wet recirculating cooling systems – 

wet cooling towers and cooling ponds. The most common type of recirculating system 

uses wet cooling towers to dissipate the heat from the cooling water to the atmosphere 

(Figure 3). In wet recirculating systems, warm cooling water is pumped from the steam 

condenser to a cooling tower. The heat from the warm water is transferred to ambient air 

flowing through the cooling tower. In the process, a portion of the warm water 

evaporates from the cooling tower and forms a water vapor plume. The cooled water is 

then recycled back to the condenser. Because of evaporative losses, a portion of the 

cooling water needs to be discharged from the system – known as blowdown − to prevent 

the buildup of minerals and sediment in the water that could adversely affect 

performance. The quantity of blowdown required for a particular cooling water system is 

determined by a parameter known as “cycles of concentration”, which is defined as the 

ratio of dissolved solids in the circulating water to that in the makeup water. As the 

cycles of concentration increases, the quantity of blowdown and makeup water decreases. 

For a wet recirculating system, only makeup water needs to be withdrawn from the local 

water body to replace water lost through evaporation and blowdown. As a result, plants 

equipped with wet recirculating systems have relatively low water withdrawal, but high 

water consumption, compared to once-through systems. Wet cooling towers are 

available in two basic designs – mechanical draft and natural draft. Mechanical draft 

towers utilize a fan to move ambient air through the tower, while natural draft towers rely 

on the difference in air density between the warm air in the tower and the cooler ambient 

air outside the tower to draw the air up through the tower. In both designs, the warm 

cooling water is discharged into the tower for direct contact with the ambient air. A 

cooling pond serves the same purpose as a wet cooling tower, but relies on natural 

conduction/convection heat transfer from the water to the atmosphere as well as 

evaporation to cool the recirculating water. 

Dry cooling systems can use either a direct or indirect air cooling process. In direct dry 

cooling, the turbine exhaust steam flows through tubes of an air-cooled condenser (ACC) 

where the steam is cooled directly via conductive heat transfer using a high flow rate of 

ambient air that is blown by fans across the outside surface of the tubes. Therefore, 

cooling water is not used in the direct air-cooled system. For indirect dry cooling, a 

conventional water-cooled surface condenser is used to condense the turbine exhaust 

steam, but a dry cooling tower, similar in design to an ACC, is used to conductively 

transfer the heat from the water to the ambient air. As a result, there is no evaporative 

loss of cooling water with an indirect dry cooling system and both water withdrawal and 

consumption are minimal. 
Freshwater Needs for Thermoelectric Generation, September 2007 

13 

Figure 3 - Wet Recirculating Cooling Water System for a 520-MW Coal-Fired Boiler 

In the United States, existing thermoelectric power plants use each of these types of 

systems, with estimates indicating that 42.7% of generating capacity is once-through, 

41.9% wet recirculating, 0.9% dry cooling, and 14.5% cooling ponds.11 Table 2 presents 

a summary of the current percentage distribution of cooling technology by generation 

type. It should be noted that the data for combined cycle plants represents only about 7% 

of the total combined cycle plants currently in operation. This is because not all plants 

provided cooling data, so the table was created using information available at the time. If 

all plants reported cooling data, it is most likely that dry cooling would represent a much 

smaller percentage of the total combined cycle cooling. 

Table 1 - Cooling Technology by Generation Type 

Percentage (%) 

Generation 

Type 

Wet 

Recirculating 

OnceThrough Dry Cooling 

Pond 

Coal 48.0% 39.1% 0.2% 12.7% 

Fossil NonCoal 23.8% 59.2% 0.0% 17.1% 

Combined 

Cycle 30.8% 8.6% 59.0% 1.7% 

Nuclear 43.6% 38.1% 0.0% 18.3% 

Total 41.9% 42.7% 0.9% 14.5% 

3,804,950 lb/hr 

Boiler 

Feedwater

Steam

Condensate

Warm Water

Cool Water Steam 

Condenser

Evaporation 

& Drift 

Make-up Water Blowdown Water

5,188 gpm 1,297 gpm 

25 oF Rise 

187,600 gpm 

520 MW 

3,891 gpm 

7,645 gpm 

Generator

Turbine

Cooling 

Tower

Boiler 
Freshwater Needs for Thermoelectric Generation, September 2007 

14 

Historically, the choice of cooling technology for a particular plant depended on the 

quantity and quality of local water sources coupled with cost and performance 

characteristics of the different systems. The use of closed-loop systems, however, is 

likely to become much more pronounced in the future due to the Clean Water Act 316(b) 

provisions and public pressures.d

 Although once-through cooling systems can still be 

legally permitted under 316(b), the complexity of the permitting, analysis and reporting 

requirements may discourage their use. 

Projections of Thermoelectric Capacity and Generation 

The EIA publishes its Annual Energy Outlook (AEO) to provide a forecast as to where 

the energy sector will be in the future, including projections of thermoelectric capacity 

and generation. The AEO projections are based on EIA’s National Energy Modeling 

System (NEMS), which is revised yearly to reflect technology advances, supply and 

demand adjustments, and other market forces. AEO 2007 projections of capacity and 

generation to 2030 are used in this analysis to calculate future thermoelectric generation 

water withdrawal and consumption. Table 3 summarizes projected changes in U.S. 

electric power generating capacity from 2005 to 2030. Coal-fired generating capacity is 

projected to increase by 158 GW from 2005 to 2030. 

Table 2 - AEO 2007 Thermoelectric Capacity Projections – 2005 to 2030 

 2005 2010 2015 2020 2025 2030 

Net Generating Capacity 

Coal Steam 310.7 320.9 323.1 347.2 393.7 450 

Other Fossil Steam 121.3 119.5 89.8 89.3 88.9 87.5 

Combined Cycle 176.7 193.3 195.6 203.8 210.8 211.6 

Nuclear 100 100.5 102.5 111.7 111.7 112.6 

Total 

Thermoelectric 708.7 734.2 711 752 805.1 861.7 

Cumulative Additions (Planned and Unplanned) - 2005 Baseline 

Coal Steam 0 11.5 18 42.3 88.7 145 

Other Fossil Steam 0 0 0 0 0 0 

Combined Cycle 0 16.7 19 27.3 34.2 35.1 

Nuclear 0 0 0.5 9 9 12.5 

Total 

Thermoelectric 0 28.2 37.5 78.6 131.9 192.6 

Cumulative Retirements - 2005 Baseline 

Coal Steam 0 1.2 5.6 5.7 5.7 5.7 

Other Fossil Steam 0 1.8 31.5 32 32.4 33.8 

Combined Cycle 0 0.1 0.1 0.1 0.1 0.1 

Nuclear 0 0 0 0 0 2.6 

Total 

Thermoelectric 0 3.1 37.2 37.8 38.2 42.2 

 

d

 See Appendix A for more details on CWA 316(b). 
Freshwater Needs for Thermoelectric Generation, September 2007 

15 

AEO 2007 also includes a breakout of thermoelectric capacity and generation by region 

using the former 13 North American Electric Reliability Council (NERC) control regions, 

excluding Alaska and Hawaii. This analysis presents the regional data according to the 

former NERC regions because the data from AEO 2007 uses those regions. These NERC 

regions are shown in Figure 4 and a description of the regional abbreviations is provided 

in Table 3. 

Figure 4 - NERC Regions 

Table 3 – Description of NERC Regions 

Region 

Number 

Abbreviation Region 

1 ECAR East Central Area Reliability Coordination Agreement 

2 ERCOT Electric Reliability Council of Texas 

3 MAAC Mid-Atlantic Area Council 

4 MAIN Mid-America Interconnected Network 

5 MAPP Mid-Continent Area Power Pool 

6 NPCC/NY Northeast Power Coordinating Council/New York 

7 NPCC/NE Northeast Power Coordinating Council/New England 

8 FRCC Florida Reliability Coordinating Council 

9 SERC Southeastern Electric Reliability Council 

10 SPP Southwest Power Pool 

11 WECC/NWPP Western Electricity Coordinating Council/Northwest Power 

Pool 

12 WECC/RM Western Electricity Coordinating Council/Rocky Mountains, 

AZ, NM, southern NV 

13 WECC/CA Western Electricity Coordinating Council/California 

WECC/ 

NWPP MAPP

MAIN

ECAR 

NPCC/ 

NY 

NPCC/

NE 

MACC

FRCC

SPP

ERCOT

WECC/ 

RM 

WECC/ 

CA 

SERC 
Freshwater Needs for Thermoelectric Generation, September 2007 

16 

Figure 5 and Figure 6 show that thermoelectric capacity (GW) and generation (billion 

kWh) will increase in most of the NERC regions by 2030, reflecting required generation 

to meet anticipated demand growth. Both capacity and generation growth are presented 

because the two are not necessarily directly linked. For example, if under-utilized 

capacity exists in a region, generation can increase without a change to capacity. The 

regions of greatest growth are indicated in the figures, and correspond to the areas where 

water concerns are growing as well, particularly in the west. All of the WECC regions 

show approximately a 50% increase in thermoelectric generating capacity. 

Figure 5 - Thermoelectric Capacity, 2005 vs. 2030, by NERC region 

0

50

100

150

200

250

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Capacity (GW)

Thermoelectric Capacity, 2005 Incremental Thermoelectric Capacity, 2005-2030

Figure 7 and Figure 8 present the same information for the portion of the total 

thermoelectric capacity and generation that correspond to coal-fired plants. Coal-fired 

capacity and generation will also increase in most of the NERC regions by 2030. The 

regions with growing water concerns are also projected to experience greater than 100% 

increase in incremental coal capacity.

Regions with greater 

then 50% increase in 

incremental capacity – 

same as regions of 

growing water concerns 
Freshwater Needs for Thermoelectric Generation, September 2007 

17 

Figure 6 - Thermoelectric Generation, 2005 vs. 2030, by NERC region 

0

200

400

600

800

1000

1200

1400

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Gerneration (billion kWh)

Thermoelectric Generation, 2005 Incremental Thermoelectric Generation, 2005-2030

Figure 7 – Coal-Fired Capacity, 2005 vs. 2030, by NERC region 

-10

10

30

50

70

90

110

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Capacity (GW)

Coal-Fired Capacity, 2005 Incremental Coal-Fired Capacity, 2005-2030

Regions with greater 

then 100% increase in 

incremental coal-fired 

capacity 
Freshwater Needs for Thermoelectric Generation, September 2007 

18 

Figure 8 – Coal-Fired Generation, 2005 vs. 2030, by NERC region 

0

100

200

300

400

500

600

700

800

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Gerneration (billion kWh)

Coal-Fired Generation, 2005 Incremental Coal-Fired Generation, 2005-2030

Assumptions and Methodology 

Using the electricity capacity and generation forecasts provided by AEO 2007 and the 

water use estimates provided by EIA-767, an estimate of freshwater consumption and 

withdrawal was obtained for the U.S. thermoelectric power generation industry through 

2030. Table 4 lists the resources used for this analysis, and summarizes how each 

resource supported the analysis. 

These sources provided data from which water withdrawal and consumption factors 

(water-use scaling factors) could be calculated for a given category of power plant in a 

given region. The water use scaling factors indicate average rate of water use per unit of 

electrical output – gallons per hour per kilowatt (gal/kWh). 

Figure 9 provides a flowchart depiction of the methodology used to conduct the analysis. 

A brief description of each step in the process is presented below. A more detailed 

discussion of the methodology is provided in Appendix B. 
Freshwater Needs for Thermoelectric Generation, September 2007 

19 

Table 4 – Data Resources 

Resource Type of Data 

AEO 2007 • Projections of capacity and generation by 

NERC region for coal, non-coal fossil, and 

nuclear plants 

• Coal capacity, generation, and capacity factor 

breakdown by four categories: existing 

unscrubbed, existing scrubbed, new PC 

(scrubbed), and IGCC 

NETL 2005 Coal Power Plant Database – 

Including data from 2003 EIA-767 

• Plant generation 

• Average water withdrawal and consumption 

• Cooling water source 

• Type of cooling water system 

• Type of boiler 

• Type of FGD system 

EIA-860 • Plant location by NERC region 

• Plant summer capacity 

CMU/NETL – Integrated Environmental Control 

Model (IECM) 

• Water use factors for wet FGD and dry FGD 

Power Plant Water Consumption Study, August 

2005 – DOE/NETL 

• Water use factors for boiler make-up 

Cost and Performance Comparison Baseline for 

Fossil Energy Power Plants, Volume 1: Bituminous 

Coal and Natural Gas to Electricity. April 2007, 

DOE/NETL. 

• Water use factors for IGCC plants 

• Water use for PC and IGCC plants employing 

carbon capture technologies 

Figure 9 - Methodology for the 2006 Water Needs Analysis 

Develop 

model plants 

to represent 

existing 

thermoelectric fleet

Calculate 

water 

withdrawal 

and 

consumption 

factors

Quality 

control and 

model 

validation

Develop 

future 

cases to 

evaluate

Calculate 

regional 

withdrawal 

and 

consumption 

to 2030

Step 1 Step 2 Step 3 Step 4 Step 5

Step 1: Develop model plants 

To obtain the resolution desired for this analysis, water withdrawal and consumption 

factors were determined for a large number of plant configurations, based on location, 

generation type, cooling water source, cooling system type, and where applicable, boiler 

type and type of FGD system. The existing thermoelectric fleet was segregated into 

numerous configurations, called “model plants” using data contained in several sources: 

the NETL Coal Plant Database, EIA-767, and EIA-860. 

Fresh versus Saline Water 

The analysis focuses on freshwater impacts associated with future thermoelectric power 

plants. It is recognized that saline water is used at a number of power plants in oncethrough cooling systems. However, in light of 316(b) regulations for new facilities that 
Freshwater Needs for Thermoelectric Generation, September 2007 

20 

favor recirculating systems and siting difficulties for coastal-based power plants, the 

percentage of saline-based cooling systems at new plants is expected to be relatively 

small. Furthermore, no distinction is made between surface and groundwater; both are 

included as freshwater. 

Step 2: Calculate water withdrawal and consumption factors 

For each model plant defined in Step 1, water withdrawal and consumption factors were 

calculated using the data sources outlined above. For coal-fired plants, the water 

withdrawal and consumption factors were based on the sum of three components: 

1) boiler make-up water; 2) FGD make-up water; and 3) cooling water. Average water 

withdrawal (gal/hr), average water consumption (gal/hr), and summer capacity were used 

to calculate average withdrawal and consumption scaling factors (gal/kWh) for each 

model plant in each of the NERC regions. Nuclear, oil steam, gas steam, and natural gas 

combined-cycle plants were classified according to NERC region, cooling water source 

(fresh or saline), and cooling water system (recirculating or once-through). A summary 

of the regional water withdrawal and consumption factors used in the analysis is included 

in Appendix D.

The following is a brief discussion of the more important assumptions made in 

calculating the water use factors. 

Evaporative Loss Associated with Once-Through Cooling Systems 

One important point needs to be made regarding consumption levels for once-through 

cooling systems. Although once-through consumption levels are extremely small at the 

plant boundaries, downstream consumption (evaporation) due to the elevated discharge 

temperature is not insignificant. An Electric Power Research Institute (EPRI) study 

estimated that once-through consumption levels, when including downstream 

evaporation, are less than, but of the same magnitude as, wet recirculating cooling system 

consumption levels.12 EPRI estimated once-through fossil plant water consumption 

levels of 300 gal/MWh versus closed-loop water consumption levels of 480 gal/MWh. 

For nuclear plants, the corresponding numbers are 400 gal/MWh and 720 gal/MWh. 

However, since this analysis relies on the water withdrawal and consumption data 

reported by power plants to EIA, it does not account for this downstream evaporative 

loss. 

Subcritical versus Supercritical Boiler for New Coal-Fired Power Plants 

The analysis uses different water use scaling factors for coal-fired power plants based on 

boiler type. A supercritical boiler is more efficient and therefore requires less cooling 

water flow than a subcritical boiler for an equivalent amount of electrical generation 

output. Future coal-fired plant capacity is assumed to be split as 75 supercritical and 25 

subcritical for the water analysis. Appendix C provides additional background 

information and justification for this assumption. 
Freshwater Needs for Thermoelectric Generation, September 2007 

21 

Flue Gas Desulfurization Systems for Retrofit and New Coal-Fired Power Plants 

The FGD make-up water requirement depends on the type of FGD system – either wet or 

dry. Dry FGD systems require much less water than wet FGD systems, for example, so 

different factors were used. The FGD make-up water factors were calculated using 

material balance data contained in Carnegie Mellon University’s Integrated 

Environmental Control Model (IECM).13 The amount of existing non-scrubbed capacity 

projected to be retrofit with FGD was obtained from EIA based on AEO2007 data. It 

was further assumed that all new coal-fired plants would be equipped with FGD. Since 

emission regulations do not dictate technology selection, the analysis apportions FGD 

type to retrofit and new capacity additions based on the existing split in the coal-fired 

power fleet (by summer capacity), which is 90% wet/10% dry. 

Integrated Gasification Combined Cycle Plants 

Water requirements for integrated gasification combined cycle (IGCC) plants were 

obtained from a baseline study conducted by DOE/NETL in 2007.15 The average 

withdrawal and consumption estimates of three IGCC processes in the study were used 

for this analysis. The water requirements for IGCC facilities differ from those at 

pulverized coal facilities. While both require cooling water, IGCC requires substantially 

less since a large fraction of the output from an IGCC plant is produced from the 

combustion turbines, which require minimal water. Moreover, since IGCC relies on 

water for significant process (non-cooling) use, it is unlikely that a saline water source 

would be desirable. The model IGCC coal plant, therefore, is restricted to freshwater use. 

Natural Gas Combined Cycle Plants 

In calculating water withdrawal and consumption quantities for combined-cycle plants, 

an adjustment was made to account for the fact that the gas turbine portion of the plant 

does not require cooling water. The design capacity of the gas turbine portion of a 

combined-cycle facility is typically twice that of the steam turbine portion; in other 

words, two-thirds of a combined-cycle plant’s total output is derived from the gas 

turbine(s). Therefore, only about one-third of the plant output is used for steam 

generation, with its associated water requirements. For this analysis, water withdrawal 

and consumption factors were applied to only one-third of the combined-cycle capacity. 

Appendix E provides additional background information and justification for this 

assumption. 

Step 3: Quality Control and Model Validation 

Step 3 represents efforts designed to ensure quality control for the analysis. The water 

withdrawal and consumption factors that were used in the model were obtained through a 

rigorous statistical evaluation of data from EIA. SPSS statistical software was utilized to 

generate boxplots of data that were used to identify outliers. These outliers were not 

considered during the calculation of water withdrawal and consumption factors. The 

following is a detailed description of the process used to identify outliers. 
Freshwater Needs for Thermoelectric Generation, September 2007 

22 

For each coal, fossil non-coal, and nuclear plant identified in EIA-767, a withdrawal 

usage factor (gal/MWh) was calculated. The plants were then segregated into the 

following groups by fuel, cooling system type, and boiler type (where applicable): 

• Coal Recirculating Subcritical 

• Coal Recirculating Supercritical 

• Coal Once-Through Subcritical 

• Coal Once-Through Supercritical 

• Coal Cooling Pond Subcritical 

• Coal Cooling Pond Supercritical 

• Fossil Non-Coal Recirculating 

• Fossil Non-Coal Once-Through 

• Fossil Non-Coal Cooling Pond 

• Nuclear Recirculating 

• Nuclear Once-Through 

For once-through and cooling pond plants, withdrawal usage factors were multiplied by 

the corresponding cooling system design temperature rise to normalize the data. For 

recirculating plants, this step was not taken since the temperature rise would affect the 

size of the cooling tower, but not the amount of evaporative loss or blowdown that 

determine the make-up withdrawal rate. 

The appropriate data (gal/MWh for recirculating plants and gal/MWh x ΔT for oncethrough plants) for the above categories was collected and inserted into SPSS to generate 

boxplots of the data in each of the above categories to identify outliers. An outlier is a 

data point "far away" from the rest of the data. Some of the water usage data points 

calculated from the EIA databases were further away from the general data population 

than what seems reasonable. The outliers can indicate faulty data entry, or possibly 

unusual operation conditions. For purposes of calculating the regional water usage 

factors for this study, it was decided to identify and eliminate the statistically significant 

outliers using the box plot technique described below. 

Boxplots are a graphical tool used to identify the center, spread, extent and nature of any 

departure from symmetry, and outliers contained in a data set. To construct such a plot, 

data must be ordered in value from smallest to largest. The lower fourth and upper fourth 

of the data can then be identified. The lower fourth is the median of the smallest n/2 

observations when n is even, and the median of the smallest (n+1)/2 observations when n 

is odd. The upper fourth is the median of the largest n/2 observations when n is even, and 

the median of the largest (n+1)/2 observations when n is odd. The fourth spread, fs, is the 

difference between the upper and lower fourths. Any observation farther than 1.5fs from 

the closest fourth is a mild outlier while those observations farther than 3fs from the 

closest fourth are extreme outliers26. 

Figure 10 provides an example of a typical boxplot. In this plot, the upper edge of the 

box represents the upper fourth, while the lower edge represents the lower fourth. The 
Freshwater Needs for Thermoelectric Generation, September 2007 

23 

horizontal line passing through the box indicates the median value of the data. The 

circles above and below the box indicate outliers while the vertical lines extending above 

and below the box represent the highest and lowest observations not considered outliers. 

Figure 10 – Example Boxplot27 

Outliers identified by SPSS boxplots were eliminated from the calculation of water usage 

factors. Table 5 presents the number of data points available as well as the number of 

outliers identified in each of the 11 categories considered. 

Table 5 – Data Points and Outlier Totals for QA/QC Categories 

Category Data Points Available Outliers Eliminated 

Coal Recirculating Subcritical 199 51 

Coal Recirculating Supercritical 46 7 

Coal Once-Through Subcritical 400 71 

Coal Once-Through Supercritical 40 3 

Coal Cooling Pond Subcritical 62 0 

Coal Cooling Pond Supercritical 9 4 

Fossil Non-Coal Recirculating 88 34 

Fossil Non-Coal Once-Through 289 55 

Fossil Non-Coal Cooling Pond 6 0 

Nuclear Recirculating 39 7 

Nuclear Once-Through 55 9 

Appendix F presents SPSS boxplots generated from the original data for each of the 

above categories as well as boxplots generated after outliers were eliminated from the 

data set. 

Step 4: Develop Future Cases 

Future water withdrawal and consumption for the U.S. thermoelectric generation sector 

are estimated for five cases – one reflecting status quo conditions, two reflecting varying 
Freshwater Needs for Thermoelectric Generation, September 2007 

24 

levels of regulations regarding cooling water source, one incorporating dry cooling, and 

one reflecting regulatory pressures to convert existing once-through capacity to 

recirculating capacity. Table 6 presents the description and rationale for the five selected 

cases. 

Table 6 – Case Descriptions for 2007 Water Needs Analysis 

Case Description Rationale 

Case 1: Additions and retirements 

proportional to current water source 

and type of cooling system. 

Status quo scenario case. Assumes additions and retirements 

follow current trends. 

Case 2: All additions use freshwater 

and wet recirculating cooling, while 

retirements are proportional to 

current water source and cooling 

system. 

Regulatory-driven case. Assumes 316(b) and future regulations 

dictate the use of recirculating systems for all new capacity. 

Retirement decisions hinge on age and operational costs rather 

than water source and type of cooling system. 

Case 3: 90% of additions use 

freshwater and wet recirculating 

cooling, and 10% of additions use 

saline water and once-through 

cooling, while retirements are 

proportional to current water source 

and cooling system. 

Regulatory-light case. New additions favor the use of freshwater 

recirculating systems, but some saline capacity is permitted. 

Retirement decisions remain tied to age and operational costs, 

tracking current source withdrawals. 

Case 4: 25% of additions use dry 

cooling and 75% of additions use 

freshwater and wet recirculating 

cooling. Retirements are proportional 

to current water source and cooling 

system. 

Dry cooling case. Regulatory and public pressures result in 

significant market penetration of dry cooling technology. 

Retirement decisions remain tied to age and operational costs, 

tracking current source withdrawals. 

Case 5: Additions use freshwater and 

wet recirculating cooling, while 

retirements are proportional to 

current water source and cooling 

system. 5% of existing freshwater 

once-through cooling capacity 

retrofitted with wet recirculating 

cooling every 5 years starting in 

2010. 

Conversion case. Same as Case 2, except regulatory and public 

pressures compel state agencies to dictate the conversion of a 

significant amount of existing freshwater once-through cooling 

systems to wet recirculating. 

The five cases were selected to cover the range of possible design choices for new power 

plants including the source of water (fresh or saline) and type of cooling system (wet 

recirculating or dry). In addition, Case 5 assumes that 25% of existing power plants with 

a once-through cooling system are retrofit with a wet recirculating system. For all five 

cases, it is assumed that plant retirements occur proportional to current water source and 

cooling system type. 
Freshwater Needs for Thermoelectric Generation, September 2007 

25 

Step 5: Calculate regional withdrawal and consumption to 2030 

Step 5 integrates the water withdrawal and consumption factors calculated in Step 2 with 

the various cases defined in Step 4 to assess the regional and national impacts on water 

withdrawal and consumption out to 2030. The Annual Energy Outlook provides 

projections of future electricity generating capacity by year, by generation type and by 

NERC region. Apportioning this capacity among the chosen model plants for a given 

case and then applying the water withdrawal and consumption factors enabled the 

calculation of estimated water withdrawal and consumption trends for each of the five 

future cases. 

Water Use for CO2 Capture Equipped Coal-Fired Power Plants 

Carbon capture technologies could increase the water demand on thermoelectric power 

plants. With increasing political and public interest regarding “climate change” and CO2

mitigation, coupled with future water usage concerns, it is of interest to estimate and 

explore the possible effects CO2 mitigation will have on future water demands. EIA 

forecasts a 45% increase in coal-fired generation by the year 20301

. Current carbon 

capture technologies under development for coal-based power generation require large 

amounts of water. This carbon capture analysis assumes that carbon mitigation policies 

will be put in place in near future. The assumed outcome of those policies would be that 

all PC plants with scrubbers and IGCC plants would utilize carbon capture technologies 

by 2030. The deployed carbon capture technologies used in this analysis remove a 

nominal 90% of the CO2 that would be generated from the fuel carbon. This analysis 

follows the EIA AEO 2007 forecast and assumes the generation mix would not change 

under such a climate control scenario. Though it is recognized that such a policy 

regarding climate control could impact fossil-fueled power generation, this analysis 

provides an upper boundary of the estimated additional water usage for carbon capture. 

AEO 2007 projects that in the year 2030, 62 MW of power will be generated from PC 

plants that do not have scrubbers for sulfur control. Therefore, this analysis does not 

include those plants for CO2 capture. It is assumed that the PC plants without scrubbers 

are the oldest plants and that it is not feasible to retrofit them with CO2 capture 

technologies. Therefore these plants would be subjected to carbon trading. 

The carbon capture section of this analysis uses a 1st order approach derived from a 

recent NETL study of the cost and performance impacts associated with CCS 

technologies on coal-based power plants.15 Water consumption and withdrawal factors, 

gallons used per energy generated on a net generation basis, from the detailed study were 

developed for the subcritical and supercritical plants. The water use for the carbon 

capture ready IGCC plants was the average of the three gasification technologies studied 

in the detailed report since the types of gasifiers used are not known for future generation. 

The water requirements, at full load, for PC and IGCC plants with and without carbon 

capture derived from the detail performance study and used in this analysis is shown in 

Figure 11. All additional cooling systems required for the retrofits and all new PC and 

IGCC capture ready plants are assumed to be recirculating systems based on current 

regulations and concerns with once-through systems. 
Freshwater Needs for Thermoelectric Generation, September 2007 

26 

Figure 11 - Relative Water Usage for new PC and IGCC Plants 

0

200

400

600

800

1,000

1,200

1,400

1,600

Water (gal/MWhr)

Subcr itical PC Subcr itical PC w/ CO2

Captur e

Super cr itical PC Super cr itical PC w/ CO2

Captur e

IGCC IGCC w/ CO2 Captur e

Withdrawal

Consumption

* IGCC data are the averages of three different gasification technologies 

Carbon capture technologies require auxiliary power also termed “parasitic” load, which 

lowers the net exported power. This analysis assumes that all new additions include 

carbon capture technologies and that these new builds will meet the required capacity by 

accounting for their own parasitic load. The existing PC plants that will be retrofitted 

with carbon capture technologies will be de-rated due to the parasitic load. Net outputs 

from retrofitted PC plants are de-rated by approximately 30%14, resulting in 72.7 GW of 

required replacement power. Since the EIA data did not include additions for a carbon 

capture case, this analysis looks at three possible scenarios to account for the capacity 

loss. 

Scenario 1, the “conservative” scenario, only accounts for the increased water 

requirements for the carbon capture technologies used for the retrofits and new builds and 

does not account for the 72.7 GW of reduced capacity due to the retrofits. For this 

analysis, it is assumed that the reduced capacity will be replaced with some other “nonthermoelectric” generation that doesn’t require cooling water. The additional water 

requirements, if applicable, for these other technologies are not accounted for in this 

scenario. This scenario is an underestimate to serve as the lower boundary of the 

projections and as the initial step for the incremental water increase for scenarios 2 and 3 

to build off of. 

Scenario 2 builds off of scenario 1 and assumes that the additional capacity needed to 

make up for the parasitic loss of the retrofits are supplemented by 72.7 GW of new IGCC 

plants with recirculating cooling and include carbon capture technologies. Cases 3 and 4 
Freshwater Needs for Thermoelectric Generation, September 2007 

27 

are applicable to these new builds where 10% of the new IGCC builds us saline water 

(case 3) and 25% of the new builds use dry cooling (case 4). 

Scenario 3 is similar to scenario 2 except it assumes that the additional capacity needed 

to make up for the parasitic loss of the retrofits are supplemented by 72.7 GW of new 

supercritical PC power plants with recirculating cooling and include carbon capture 

technologies. Cases 3 and 4 are applicable to these new builds where 10% of the new 

supercritical builds us saline water (case 3) and 25% of the new builds use dry cooling 

(case 4). 

PC and IGCC carbon capture technologies increase the plants overall water use. For the 

PC cases with carbon capture, the increase in water consumption, compared to a plant 

without carbon capture, is greatly influenced by the cooling water requirements of the 

CO2 capture process. The cooling water for the overall CO2 capture process is required 

to reduce the flue gas temperature exiting the FGD down to below 100°F, remove heat 

input by the stripping steam to cool the solvent, remove heat input from the auxiliary 

electric loads, and remove heat in the CO2 compressor intercoolers.15 The increased 

water use for the IGCC plants in largely due to the steam used in the water gas shift 

reaction. More detail regarding the carbon capture technologies used for this analysis is 

described in Appendix G. 

Results

Water withdrawal and consumption projections for each of the five cases are presented 

below both nationally and regionally for total thermoelectric generation and the coal-fired 

generation component of thermoelectric generation. The increased water use for 

capturing CO2 nationally in the year 2030 is also shown. 

Thermoelectric Generation – National Level Summary 

The analysis projects that by 2030, average daily national freshwater withdrawals 

required to meet the needs of U.S. thermoelectric power generation could range from 

117.5 BGD to 158.0 BGD depending upon case assumptions. This compares with USGS 

estimates that thermoelectric power plants withdrew approximately 132 BGD of 

freshwater in 1995 and approximately 136 BGD of freshwater in 2000. Table 7 presents 

the range of average daily national freshwater withdrawal for each of the five cases from 

2005 through 2030. This same data is presented graphically in Figure 12. 
Freshwater Needs for Thermoelectric Generation, September 2007 

28 

Table 7 – Average National Freshwater Withdrawal for Thermoelectric Power Generation (BGD) 

 2005 2010 2015 2020 2025 2030 

Case 1 149.0 152.3 147.0 153.8 157.5 157.9 

Case 2 149.0 149.2 143.4 144.1 144.4 143.8 

Case 3 149.0 149.2 143.4 144.0 144.2 143.6 

Case 4 149.0 149.0 143.1 143.5 143.4 142.7 

Case 5 149.0 143.3 131.6 127.2 122.6 117.5 

 

Minimum 149.0 143.3 131.6 127.2 122.6 117.5 

Maximum 149.0 152.3 147.0 153.8 157.5 157.9 

Figure 12 – Average Daily National Freshwater Withdrawal for Thermoelectric Power Generation 

0

20

40

60

80

100

120

140

160

180

2005 2010 2015 2020 2025 2030

Daily Withdrawals (BGD)

600

650

700

750

800

850

900

Thermoelectric Generating 

Capacity (GW)

Case 1

Case 2

Case 3

Case 4

Case 5

Generation

The analysis projects that by 2030, average daily national freshwater consumption 

resulting from U.S. thermoelectric power generation could range from 6.1 BGD to 9.1 

BGD depending upon case assumptions. This compares with USGS estimates that in 

1995, freshwater consumption by U.S. thermoelectric power plants was approximately 

3.3 BGD. Table 8 presents the range of average daily national freshwater consumption 

for each of the five cases from 2005 through 2030. This same data is presented 

graphically in Figure 13. 
Freshwater Needs for Thermoelectric Generation, September 2007 

29 

Table 8 – Average National Freshwater Consumption for Thermoelectric Power Generation (BGD) 

 2005 2010 2015 2020 2025 2030 

Case 1 6.1 6.3 6.6 7.0 7.5 7.9 

Case 2 6.1 6.3 6.7 7.2 7.7 8.2 

Case 3 6.1 6.3 6.6 7.2 7.6 8.1 

Case 4 6.1 6.3 6.6 7.0 7.4 7.8 

Case 5 6.1 6.5 7.0 7.8 8.4 9.1 

Minimum 6.1 6.3 6.6 7.0 7.4 7.8 

Maximum 6.1 6.5 7.0 7.8 8.4 9.1 

Saline water usage was added to the model and the results are included at the national 

level for this update. Figure 14 and Figure 15 are similar to Figure 12 and Figure 13, 

except saline water usage is added to the graphs illustrating that nationally saline water 

withdrawals are approximately one-third that of freshwater withdrawals. Saline water 

consumption for the thermoelectric plants is negligible compared to freshwater 

consumption, since most plants using saline water utilize a once-through cooling system. 

Figure 13 – Average Daily National Freshwater Consumption for Thermoelectric Power Generation 

0

1

2

3

4

5

6

7

8

9

10

2005 2010 2015 2020 2025 2030

Water Consumption (BGD)

600

650

700

750

800

850

900

Thermoelectric Generating 

Capacity (GW)

Case 1

Case 2

Case 3

Case 4

Case 5

Generation

Thermoelectric Generation - National Level Results by Case 

Case 1 

Total thermoelectric generation freshwater withdrawal is projected to remain relatively 

constant from 2005 through 2030 for Case 1 – increasing slightly from 149 BGD to 157.9 

BGD – despite the overall 22% increase in generation capacity from 709 GW to 862 GW. 

At first glance this result seems inconsistent with the Case 1 status quo assumptions that 

additions and retirements are proportional to current water source and type of cooling 

water system. The explanation for this apparent inconsistency is that AEO2007 projects 
Freshwater Needs for Thermoelectric Generation, September 2007 

30 

capacity retirements primarily from the non-FGD coal and non-coal fossil generation 

categories, which have a relatively high proportion of once-through cooling systems, 

while capacity additions are primarily in the FGD coal, IGCC, and NGCC generation 

categories, which have a relatively high proportion of wet recirculating cooling systems. 

In addition, the steam cycle portion of IGCC and NGCC plants is only one-third of their 

total capacity. Since average freshwater withdrawal for once-through cooling is 

significantly higher than wet recirculating cooling – approximately 25 gal/kWh versus 

0.5 gal/kWh – the net effect is no significant change in overall freshwater withdrawal 

over the next 25 years. 

Figure 14 – Average Daily National Freshwater and Saline Withdrawals for Thermoelectric Power 

Generation 

0

20

40

60

80

100

120

140

160

180

2005 2010 2015 2020 2025 2030

Water Withdrawals (BGD)

FW Case1

FW Case 2

FW Case 3

FW Case 4

FW Case 5

SW Case 1

SW Case 2

SW Case 3

SW Case 4

SW Case 5
Freshwater Needs for Thermoelectric Generation, September 2007 

31 

Figure 15 – Average Daily National Freshwater and Saline Consumption for Thermoelectric Power 

Generation 

0

1

2

3

4

5

6

7

8

9

10

2005 2010 2015 2020 2025 2030

Water Consumption (BGD)

FW Case1

FW Case 2

FW Case 3

FW Case 4

FW Case 5

SW Case 1

SW Case 2

SW Case 3

SW Case 4

SW Case 5

National freshwater withdrawal for each fuel type in Case 1 is presented in Figure 16. 

The figure shows the relatively unchanged total withdrawal, and the mirroring of 

scrubbed and unscrubbed coal (with scrubbed increasing over time as unscrubbed 

decreases). There is a slight decrease in fossil non-coal withdrawal and a slight increase 

in nuclear withdrawal. 

Total thermoelectric generation freshwater consumption is projected to increase 31% 

from 2005 through 2030 for Case 1 – growing from 6.1 BGD to 7.9 BGD – consistent 

with the increase in generation capacity from 862 GW to 865 GW. Since once-through 

cooling systems have minimal water consumption, the retirement of these systems does 

not have the same effect on national consumption levels as they do on withdrawal levels 

as described above. 
Freshwater Needs for Thermoelectric Generation, September 2007 

32 

Figure 16 - Average Daily National Freshwater Withdrawal by Fuel for Thermoelectric Power 

Generation – Case 1 

0

20

40

60

80

100

120

140

160

180

2005 2010 2015 2020 2025 2030

Year

Withdrawal (BGD)

TOTAL

Coal

Unscrubbed

Coal Scrubbed

Coal w / & w /out

Scrubber

Fossil Non-Coal

Combined Cycle

IGCC

Nuclear

The changes in results over time reveal some interesting trends. Although total water 

withdrawal increases slightly between 2005 and 2030, the increase is not uniform. There 

is a dip in water withdrawal in the year 2015. This dip is directly related to dip in the 

total thermoelectric generation capacity where the initial decline is due to significant 

retirement of fossil non-coal capacity (more than 29 GW) and the subsequent increase is 

due to new coal and combined-cycle additions (more than 27 GW). This difference 

appears in the other cases as well, although to a lesser degree because of competing 

influences unique to each specific case. 

The growing importance of IGCC technology is evident in the results over time. From a 

level of less than 500 MW in 2005, IGCC is expected to account for almost 67 GW by 

2030. While this capacity impact is quite large, the water impact is remarkably small – 

due primarily to the assumption that all new IGCC capacity will be equipped with wet 

recirculating cooling. In 2030, water withdrawal for IGCC is only 0.628 BGD and water 

consumption is 0.488 BGD. 

National freshwater consumption for each fuel type in Case 1 is presented in Figure 17. 

The effects of increased use of NGCC and IGCC can more clearly be seen in the 

consumption graph than in the previous withdrawal graph. Consumption increases for 

each fuel type except unscrubbed coal and fossil non-coal, which decrease. Nuclear 

water consumption increases through 2025 and then slightly decreases in 2030. 
Freshwater Needs for Thermoelectric Generation, September 2007 

33 

Figure 17 - Average Daily National Freshwater Consumption by Fuel for Thermoelectric Power 

Generation – Case 1 

0

1

2

3

4

5

6

7

8

9

2005 2010 2015 2020 2025 2030

Year

Consumption (BGD)

TOTAL

Coal Unscrubbed

Coal Scrubbed

Coal w / & w /out

Scrubber

Fossil Non-Coal

Combined Cycle

IGCC

Nuclear

Case 2 

Total thermoelectric generation freshwater withdrawal is projected to decrease 

approximately 3.5% (149.0 BGD to 143.8 BGD) from 2005 through 2030 for Case 2. 

This trend is consistent with the assumptions that all capacity additions use freshwater 

and wet recirculating cooling systems, while capacity retirements are proportional to 

current water source and type of cooling water system. 

Figure 18 displays Case 2 national withdrawal for each fuel type. The decrease in total 

withdrawal can be seen along with a decrease in fossil non-coal. The line representing 

the combination of scrubbed and unscrubbed coal remains relatively constant. Again 

scrubbed coal increases, while unscrubbed decreases. 

Similar to Case 1, total thermoelectric generation freshwater consumption is projected to 

increase – growing 38% from 6.1 BGD to 8.2 BGD between 2005 and 2030 – consistent 

with both the 22% increase in generation capacity and increased use of wet recirculating 

cooling water systems. 

Figure 19 displays Case 2 national consumption for each fuel type. Consumption 

increases are seen in every fuel type except unscrubbed coal and fossil non-coal, which 

decrease. 
Freshwater Needs for Thermoelectric Generation, September 2007 

34 

Figure 18 - Average Daily National Freshwater Withdrawal by Fuel for Thermoelectric Power 

Generation – Case 2 

0

20

40

60

80

100

120

140

160

2005 2010 2015 2020 2025 2030

Year

Withdrawal (BGD)

TOTAL

Coal Unscrubbed

Coal Scrubbed

Coal w / & w /out

Scrubber

Fossil Non-Coal

Combined Cycle

IGCC

Nuclear

Case 3 

The Case 3 assumptions are similar to Case 2, except that 90% of capacity additions use 

freshwater and wet recirculating cooling and 10% use saline water with once-through 

cooling. As might be expected, both thermoelectric generation freshwater withdrawal 

and consumption levels for Case 3 are slightly less than the respective values from 

Case 2. In 2030, freshwater withdrawal is 143.8 BGD in Case 2 compared to 143.6 in 

Case 3. Similarly, freshwater consumption in 2030 is 8.2 BGD and 8.1 BGD for Cases 2 

and 3, respectively. 

National freshwater withdrawal for each fuel type in Case 3 is presented in Figure 20. As 

the figure shows, total withdrawal decreases over time. Fossil non-coal and coal 

unscrubbed also display a noticeable decrease. National freshwater consumption for each 

fuel type in Case 3 is presented in Figure 21. Freshwater consumption is shown to 

increase over time. As with previous consumption cases, only coal unscrubbed and fossil 

non-coal consumption decreases from 2005 to 2030. 
Freshwater Needs for Thermoelectric Generation, September 2007 

35 

Figure 19 - Average Daily National Freshwater Consumption by Fuel for Thermoelectric Power 

Generation – Case 2 

0

1

2

3

4

5

6

7

8

9

2005 2010 2015 2020 2025 2030

Year

Consumption (BGD)

TOTAL

Coal Unscrubbed

Coal Scrubbed

Coal w / & w /out

Scrubber

Fossil Non-Coal

Combined Cycle

IGCC

Nuclear

Figure 20 - Average Daily National Freshwater Withdrawal by Fuel for Thermoelectric Power 

Generation – Case 3 

0

20

40

60

80

100

120

140

160

2005 2010 2015 2020 2025 2030

Year

Withdrawal (BGD)

TOTAL

Coal Unscrubbed

Coal Scrubbed

Coal w / & w /out

Scrubber

Fossil Non-Coal

Combined Cycle

IGCC

Nuclear
Freshwater Needs for Thermoelectric Generation, September 2007 

36 

Figure 21 - Average Daily National Freshwater Consumption by Fuel for Thermoelectric Power 

Generation – Case 3 

0

1

2

3

4

5

6

7

8

9

2005 2010 2015 2020 2025 2030

Year

Consumption (BGD)

TOTAL

Coal Unscrubbed

Coal Scrubbed

Coal w / & w /out

Scrubber

Fossil Non-Coal

Combined Cycle

IGCC

Nuclear

Case 4 

The potential impact of dry cooling systems on water demand is evident in the results of 

Case 4, where 25% of new capacity is assumed to be equipped with dry cooling, rather 

than wet recirculating cooling. Thermoelectric generation freshwater withdrawal and 

consumption levels for Case 4 are less than the respective values from Case 2. By 2030, 

freshwater withdrawal is projected to be approximately 1% less in Case 4 compared to 

Case 2 – 142.7 BGD vs. 143.8 BGD. More significantly, freshwater consumption is 

projected to be approximately 4% less – 7.8 BGD in Case 4 vs. 8.2 BGD in Case 2. The 

results suggest that dry cooling has the potential to play a significant roll in minimizing 

freshwater consumption in future years if technology is developed to cost effectively 

build and operate dry cooling plants. 

Figure 22 displays Case 4 national withdrawal for each fuel type. The total freshwater 

withdrawal decreases over time, as does coal unscrubbed and fossil non-coal. The line 

representing the combination of scrubbed and unscrubbed coal remains rather constant 

over the time period. Figure 23 displays Case 4 national consumption for each fuel type. 

Total consumption is shown to increase from 2005 to 2030, with only coal unscrubbed 

and fossil non-coal decreasing during that period. 
Freshwater Needs for Thermoelectric Generation, September 2007 

37 

Figure 22 - Average Daily National Freshwater Withdrawal by Fuel for Thermoelectric Power 

Generation – Case 4 

0

20

40

60

80

100

120

140

160

2005 2010 2015 2020 2025 2030

Year

Withdrawal (BGD)

TOTAL

Coal Unscrubbed

Coal Scrubbed

Coal w / & w /out

Scrubber

Fossil Non-Coal

Combined Cycle

IGCC

Nuclear

Figure 23 - Average Daily National Freshwater Consumption by Fuel for Thermoelectric Power 

Generation – Case 4 

0

1

2

3

4

5

6

7

8

9

2005 2010 2015 2020 2025 2030

Year

Consumption (BGD)

TOTAL

Coal Unscrubbed

Coal Scrubbed

Coal w / & w /out

Scrubber

Fossil Non-Coal

Combined Cycle

IGCC

Nuclear

Case 5 

The Case 5 assumptions for capacity additions and retirements are the same as Case 2. 

However, Case 5 also assumes that 25% of existing freshwater once-through cooling 

capacity is converted to wet recirculating cooling. As a result, Case 5 represents the most 

extreme conditions of the analysis and significantly impacts projections for both 

freshwater withdrawal and consumption. By 2030, total thermoelectric generation 

freshwater withdrawal is projected to be approximately 18% less in Case 5 compared to 

Case 2 – 117.5 BGD vs. 143.8 BGD – while consumption is projected to be 

approximately 11% more – 9.1 BGD in Case 5 vs. 8.2 BGD in Case 2. 
Freshwater Needs for Thermoelectric Generation, September 2007 

38 

Figure 24 - Average Daily National Freshwater Withdrawal by Fuel for Thermoelectric Power 

Generation – Case 5 

0

20

40

60

80

100

120

140

160

2005 2010 2015 2020 2025 2030

Year

Withdrawal (BGD)

TOTAL

Coal

Unscrubbed

Coal Scrubbed

Coal w / & w /out

Scrubber

Fossil Non-Coal

Combined Cycle

IGCC

Nuclear

Figure 25 - Average Daily National Freshwater Consumption by Fuel for Thermoelectric Power 

Generation – Case 5 p

0

1

2

3

4

5

6

7

8

9

10

2005 2010 2015 2020 2025 2030

Year

Consumption (BGD)

TOTAL

Coal Unscrubbed

Coal Scrubbed

Coal w / & w /out

Scrubber

Fossil Non-Coal

Combined Cycle

IGCC

Nuclear

National freshwater withdrawal for each fuel type in Case 5 is presented in Figure 24. 

Total freshwater withdrawal decreases over time, as does withdrawal for all fuel types 

except scrubbed coal (which increases as unscrubbed coal decreases). National 

freshwater consumption for each fuel type in Case 5 is presented in Figure 25. As with 

previous consumption cases, total freshwater consumption increases and unscrubbed coal 

and fossil non-coal are the only fuel types shown to decrease. 

Thermoelectric Generation – Regional Results
Freshwater Needs for Thermoelectric Generation, September 2007 

39 

Figure 26 through Figure 30 show the results of the regional freshwater withdrawal 

analysis for total U.S. thermoelectric generation comparing 2005 to 2030 for each of the 

five cases. The graphs show the SERC region has the largest increase in water 

withdrawal generally among the cases. The ECAR and ERCOT regions experience the 

largest decreases in water withdrawal in each case. Figure 31 through Figure 35 show the 

results of the regional freshwater consumption analysis for total U.S. thermoelectric 

generation comparing 2005 to 2030 for each of the five cases. All regions show an 

increase in water consumption. Inverse to the water withdrawal regional data, the 

regional consumption graphs indicate that the ECAR and ERCOT regions, along with the 

western regions WECC/CA, WECC/NWPP, and WECC/RM are all increasing water 

consumption significantly. 

Case 1 

As discussed previously, total thermoelectric generation freshwater withdrawal is 

projected to remain relatively constant from 2005 through 2030 for Case 1 – decreasing 

slightly from 149 BGD to 157.9 BGD On a regional basis, freshwater withdrawal 

increases in the MAIN, MAPP, WPCC/NE FRCC, SERC, SPP, WECC/NWPP, and 

WECC/CA regions. The WECC/CA region shows the greatest relative water withdrawal 

increase, 191% by the year 2030. Decreases occurred in all other regions, with the most 

significant decreases in the ECAR and ERCOT regions (Figure 26). 

Total thermoelectric generation freshwater consumption is projected to increase 31% 

from 2005 through 2030 for Case 1 – growing from 6.1 BGD to 7.9 BGD. Freshwater 

consumption increases in all of the regions, with relatively large percentage increases 

occurring in the NPCC/NY (372%), FRCC (112%), WECC/RM (94%), and WECC/CA 

(215%) regions (Figure 31). 
Freshwater Needs for Thermoelectric Generation, September 2007 

40 

Figure 26 – Average Daily Regional Freshwater Withdrawal for Thermoelectric Power Generation – 

Case 1 

-10

0

10

20

30

40

50

60

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawal, 2005 Incremental Water Withdrawal, 2005 - 2030
Freshwater Needs for Thermoelectric Generation, September 2007 

41 

Figure 27 – Average Daily Regional Freshwater Withdrawal for Thermoelectric Power Generation – 

Case 2 Case

-10

0

10

20

30

40

50

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawal, 2005 Incremental Water Withdrawal, 2005 - 2030

Figure 28 – Average Daily Regional Freshwater Withdrawal for Thermoelectric Power Generation – 

Case 3 

-10

0

10

20

30

40

50

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawal, 2005 Incremental Water Withdrawal, 2005 - 2030
Freshwater Needs for Thermoelectric Generation, September 2007 

42 

Figure 29 – Average Daily Regional Freshwater Withdrawal for Thermoelectric Power Generation – 

Case 4 

-10

0

10

20

30

40

50

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawal, 2005 Incremental Water Withdrawal, 2005 - 2030

Figure 30 – Average Daily Regional Freshwater Withdrawal for Thermoelectric Power Generation – 

Case 5 Case 5

-20

-10

0

10

20

30

40

50

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawal, 2005 Incremental Water Withdrawal, 2005 - 2030
Freshwater Needs for Thermoelectric Generation, September 2007 

43 

Figure 31 – Average Daily Regional Freshwater Consumption for Thermoelectric Power Generation 

– Case 1 

0

1

2

3

4

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030

Figure 32 – Average Daily Regional Freshwater Consumption for Thermoelectric Power Generation 

– Case 2 

0

1

2

3

4

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030
Freshwater Needs for Thermoelectric Generation, September 2007 

44 

Figure 33 – Average Daily Regional Freshwater Consumption for Thermoelectric Power Generation 

– Case 3 

0

1

2

3

4

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030

Figure 34 – Average Daily Regional Freshwater Consumption for Thermoelectric Power Generation 

– Case 4 

0

1

2

3

4

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030
Freshwater Needs for Thermoelectric Generation, September 2007 

45 

Figure 35 – Average Daily Regional Freshwater Consumption for Thermoelectric Power Generation 

– Case 5 

0

1

2

3

4

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030

Case 2 

Total thermoelectric generation freshwater withdrawal is projected to decrease 

approximately 3.6% (149.0 BGD to 143.8 BGD) from 2005 through 2030 for Case 2. 

Similar to Case 1, total thermoelectric generation freshwater consumption is projected to 

increase – growing 34% from 6.1 BGD to 8.2 BGD between 2005 and 2030. On a 

regional basis, freshwater withdrawal increases slightly in the FRCC and WECC/NWPP 

regions; and decreases significantly in the ECAR, SERC, and ERCOT regions (Figure 

27). Similar to Case 1, freshwater consumption increases in all of the regions, with 

relatively large percentage increases occurring in the NPCC/NY (467%), FRCC (260%), 

WECC/RM and WECC/NEPP (85%), and WECC/CA (280%) regions (Figure 32). 

Case 3 

Both thermoelectric generation freshwater withdrawal and consumption levels for Case 3 

are slightly less than the respective values from Case 2. In 2030, freshwater withdrawal 

is 143.8 BGD in Case 2 compared to 143.6 in Case 3. Similarly, freshwater consumption 

in 2030 is 8.2 BGD and 8.12 BGD for Cases 2 and 3, respectively. On a regional basis, 

freshwater withdrawal and consumption increases and decreases are also similar to 

Case 2 (Figure 28 and Figure 33). 

Case 4 

Thermoelectric generation freshwater withdrawal and consumption levels for Case 4 are 

less than the respective values from Case 2. By 2030, freshwater withdrawal is projected 

to be approximately 1% less in Case 4 compared to Case 2 – 142.6 BGD vs. 143.8 BGD. 
Freshwater Needs for Thermoelectric Generation, September 2007 

46 

More significantly, freshwater consumption is projected to be approximately 5% less – 

7.8 BGD in Case 4 vs. 8.2 BGD in Case 2. On a regional basis, freshwater withdrawal 

and consumption increases and decreases are also similar to Case 2 (Figure 29 and Figure 

34). 

Case 5 

The Case 5 assumptions for capacity additions and retirements are the same as Case 2, 

but Case 5 also assumes that 25% of existing freshwater once-through cooling capacity is 

converted to wet recirculating cooling. By 2030, total thermoelectric generation 

freshwater withdrawal is projected to be approximately 18% less in Case 5 compared to 

Case 2 – 117.5 BGD vs. 143.8 BGD – while consumption is projected to be 

approximately 11% more – 9.1 BGD in Case 5 vs. 8.2 BGD in Case 2. On a regional 

basis, freshwater withdrawal increases in the FRCC (9%) and WECC/NWPP (30%) 

regions; and decreases in all other regions, with significant decreases 25% or greater in 

the NPCC/NY (30%), ECAR (25%), and WECC/RM (28%) regions (Figure 30). 

Freshwater consumption increases in all of the regions, with relatively large percentage 

increases occurring in the NPCC/NE (87%), NPCC/NY (713%), FRCC (261%), 

WECC/NWPP (85), WECC/RM (85%), and WECC/CA (282%) regions (Figure 35). 

Saline Regional Results 

Figure 36 shows the regional saline water withdrawal and Figure 37 shows the saline 

water consumption analyses for total U.S. thermoelectric generation comparing 2005 to 

2030 for case 3. The 2007 water analysis primarily focuses on freshwater usage. These 

are the only two regional figures representing saline water use in this study. Only Case 3 

was chosen to show the regional saline water uses because this case has the highest saline 

water withdrawal and consumption of the five cases. 

On a regional basis, saline water withdrawal increases in eight regions, with relatively 

large percentage increases occurring in the ECAR (346%), MAPP (201%), and 

WECC/NWPP (221%) regions; and decreases in the other five regions, with the greatest 

decreases in the MAPP (26%) region (Figure 36). Saline water consumption increases in 

12 of the 13 regions, with relatively large percentage increases occurring in the MAPP 

(281%), WECC/NWPP (305), and WECC/CA (239%) regions (Figure 37).
Freshwater Needs for Thermoelectric Generation, September 2007 

47 

Figure 36 – Average Daily Regional Saline Water Withdrawal for Thermoelectric Power Generation 

– Case 3 

-2

0

2

4

6

8

10

12

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawal, 2005 Incremental Water Withdrawal, 2005 - 2030

Figure 37 – Average Daily Regional Saline Water Consumption for Thermoelectric Power 

Generation – Case 3 

-0.02

-0.01

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030
Freshwater Needs for Thermoelectric Generation, September 2007 

48 

Conventional Coal-Fired Generation – National Level Summary

Conventional coal-fired (not including IGCC) generating capacity is projected to increase 

by 157 GW from 2005 to 2030. The analysis projects that by 2030, average daily 

national freshwater withdrawals required to meet the needs of the U.S. coal-fired 

generation component of thermoelectric generation may decrease to 76.9 BGD (17%) or 

increase to 102.7 BGD (11%) depending upon case assumptions. Table 9 presents the 

range of average daily national freshwater withdrawal for each of the five cases from 

2005 through 2030. This same data is presented graphically in Figure 38. 

Table 9 –Average National Freshwater Withdrawal for Conventional Coal Power Generation (BGD) 

 2005 2010 2015 2020 2025 2030 

Case 1 92.3 95.9 95.6 97.7 101.4 102.7 

Case 2 92.3 92.8 92.3 92.5 92.8 93.0 

Case 3 92.3 92.8 92.2 92.4 92.7 92.9 

Case 4 92.3 92.5 92.0 92.0 92.0 92.1 

Case 5 92.3 89.3 85.2 82.2 79.5 76.9 

Maximum 92.3 95.9 95.6 97.7 101.4 102.7 

Minimum 92.3 89.3 85.2 82.2 79.5 76.9 

Figure 38 –Average Daily National Freshwater Withdrawal for Conventional Coal Power Generation 

0

20

40

60

80

100

120

2005 2010 2015 2020 2025 2030

Year

Water Withdrawal (BGD)

250

300

350

400

Coal-Fired Generation (GW)

Case 1

Case 2

Case 3

Case 4

Case 5

Coal Generation

The analysis projects that by 2030, average daily national freshwater consumption 

resulting from U.S. coal-fired power generation could range from 3.5 BGD to 4.0 BGD 

depending upon case assumptions. This represents an increase of 65% and 44% 

respectively. Table 10 presents the range of average daily national freshwater 

consumption for each of the five cases from 2005 through 2030. This same data is 

presented graphically in Figure 39. 
Freshwater Needs for Thermoelectric Generation, September 2007 

49 

Table 10 – Average National Freshwater Consumption for Conventional Coal Power Generation 

(BGD) 

 2005 2010 2015 2020 2025 2030 

Case 1 2.4 2.6 2.8 3.0 3.4 3.6 

Case 2 2.4 2.7 2.8 3.1 3.6 3.8 

Case 3 2.4 2.7 2.8 3.1 3.5 3.6 

Case 4 2.4 2.6 2.8 3.0 3.3 3.5 

Case 5 2.4 2.7 2.9 3.3 3.8 4.0 

Maximum 2.4 2.7 2.9 3.3 3.8 4.0 

Minimum 2.4 2.6 2.8 3.0 3.3 3.5 

Figure 39 – Average Daily National Freshwater Consumption for Conventional Coal Power 

Generation 

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

2005 2010 2015 2020 2025 2030

Year

Water Consumption (BGD)

250

300

350

400

Coal-Fired Generation (GW)

Case 1

Case 2

Case 3

Case 4

Case 5

Coal Generation

Conventional Coal-Fired Generation - National Level Results by Case 

Case 1 

The conventional coal portion of thermoelectric generation freshwater withdrawal is 

projected to increase approximately 11% from 2005 through 2030 for Case 1 – from 92.3 

BGD to 102.7 BGD – consistent with the overall 24% increase in generation capacity 

from 310 GW to 383 GW and roughly equal distribution of once-through and wet 

recirculating cooling water systems. More significantly, conventional coal generation 

freshwater consumption is projected to increase 50% from 2005 through 2030 for Case 1 

– growing from 2.4 BGD to 3.6 BGD. See Figure 16 and Figure 17 for plots of coal 

withdrawal and consumption from 2005-2030. 
Freshwater Needs for Thermoelectric Generation, September 2007 

50 

Case 2 

Conventional coal generation freshwater withdrawal is projected to slightly increase by 

less than 1% (92.3 BGD to 93.0 BGD) from 2005 through 2030 for Case 2. This trend is 

consistent with the assumptions that all capacity additions use freshwater and wet 

recirculating cooling systems, while capacity retirements are proportional to current 

water source and type of cooling water system. 

Similar to Case 1, conventional coal generation freshwater consumption is projected to 

increase in Case 2 – growing 58% from 2.4 BGD to 3.8 BGD between 2005 and 2030 – 

consistent with both the 24% increase in generation capacity and increased use of wet 

recirculating cooling water systems. See Figure 18 and Figure 19 for plots of coal 

withdrawal and consumption from 2005-2030. 

Case 3 

The Case 3 assumptions are similar to Case 2, except that 90% of capacity additions use 

freshwater and wet recirculating cooling and 10% use saline water with once-through 

cooling. As might be expected, both conventional coal generation freshwater withdrawal 

and consumption levels for Case 3 are slightly less than the respective values from 

Case 2. In 2030, freshwater withdrawal is 93.0 BGD in Case 2 compared to 92.9 in 

Case 3. Similarly, freshwater consumption in 2030 is 3.8 BGD and 3.6 BGD for Cases 2 

and 3, respectively. See 

Figure 20 and Figure 21 for plots of coal withdrawal and consumption from 2005-2030. 

Case 4 

The potential impact of dry cooling systems on water demand is evident in the results of 

Case 4, where 25% of new conventional coal capacity is assumed to be equipped with dry 

cooling, rather than wet recirculating cooling. Conventional coal generation freshwater 

withdrawal and consumption levels for Case 4 are less than the respective values from 

Case 2. By 2030, freshwater withdrawal is projected to be slightly less in Case 4 

compared to Case 2 – 93.0 BGD vs. 92.1 BGD. Freshwater consumption is projected to 

be approximately 8% less – 3.8 BGD in Case 4 vs. 3.5 BGD in Case 2. See Figure 22 

and Figure 23 for plots of coal withdrawal and consumption from 2005-2030. 

Case 5 

The Case 5 assumptions for conventional coal capacity additions and retirements are the 

same as Case 2. However, Case 5 also assumes that 25% of existing freshwater oncethrough cooling capacity is converted to wet recirculating cooling. As a result, Case 5 

represents the most extreme conditions of the analysis and significantly impacts 

projections for both freshwater withdrawal and consumption. By 2030, total 

conventional coal generation freshwater withdrawal is projected to be approximately 17% 

less in Case 5 compared to Case 2 – 76.9 BGD vs. 93.0 BGD – while consumption is 

projected to be approximately 5% more – 4.0 BGD in Case 5 vs. 3.8 BGD in Case 2. See 

Figure 24 and Figure 24 for plots of coal withdrawal and consumption from 2005-2030. 
Freshwater Needs for Thermoelectric Generation, September 2007 

51 

Conventional Coal-Fired Generation – Regional Results 

Figure 40 through Figure 44 shows the results of the regional water withdrawal analysis 

for total U.S. coal-fired generation comparing 2005 to 2030 for each of the five cases. 

With each successive case, the water withdrawal of the regions displays greater 

decreases, with Case 5 showing the largest overall decrease in water withdrawal. Figure 

45 through Figure 49 show the results of the regional water consumption analysis for 

total U.S. coal-fired generation comparing 2005 to 2030 for each of the five cases. Aside 

from Case 5, where water consumption increases more than other cases, the water 

consumption regionally stays rather consistent. 

Case 1 

Conventional coal generation freshwater withdrawal is projected to increase 

approximately 11% from 2005 through 2030 for Case 1 – from 92.3 BGD to 102.7 BGD. 

Conventional coal freshwater consumption is projected to increase 50% from 2005 

through 2030 for Case 1 – growing from 2.4 BGD to 3.6 BGD. On a regional basis, 

freshwater withdrawal increases in the MAIN, MAPP, SERC, FRCC, SPP, ERCOT, 

WECC/NWPP, WECC/RM, and WECC/CA regions; and decreases in the NPCC/NE 

(2%), NPCC/NY (1%), and ECAR (6%) regions (Figure 40). Freshwater consumption 

increases in all of the regions, with relatively large percentage increases occurring in the 

NPCC/NY (107%), FRCC (100%), WECC/RM (142%), and WECC/CA (457%) regions 

(Figure 45). 

Case 2 

Conventional coal generation freshwater withdrawal is projected to decrease 

approximately 1% (92.3 BGD to 93.0 BGD) from 2005 through 2030 for Case 2. Similar 

to Case 1, conventional coal generation freshwater consumption is projected to increase 

in Case 2 – growing 58% from 2.4 BGD to 3.8 BGD between 2005 and 2030. On a 

regional basis, freshwater withdrawal increases slightly in the MAPP, SERC, 

WECC/NWPP, and WECC/RM regions; and decreases slightly in the ECAR region 

(Figure 41). Similar to Case 1, freshwater consumption increases in all of the regions, 

with relatively large percentage increases occurring in the NPCC/NY (107%), MAIN 

(107%), FRCC (247%), ERCOT (115%), WECC/RM (130%), WECC/NWPP (110%), 

and WECC/CA (573%) regions (Figure 46). 

Case 3 

Both conventional coal generation freshwater withdrawal and consumption levels for 

Case 3 are slightly less than the respective values from Case 2. In 2030, freshwater 

withdrawal is 93.0 BGD in Case 2 compared to 92.9 in Case 3 (Figure 42). Similarly, 

freshwater consumption in 2030 is 3.3 BGD and 3.2 BGD for Cases 2 and 3, respectively 

(Figure 47). On a regional basis, freshwater withdrawal and consumption increases and 

decreases are also similar to Case 2. 
Freshwater Needs for Thermoelectric Generation, September 2007 

52 

Figure 40 – Average Daily Regional Freshwater Withdrawal for Coal-Fired Power Generation – 

Case 1 

-5

0

5

10

15

20

25

30

35

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawl, 2005 Incremental Water Withdraw, 2005 - 2030

Figure 41 – Average Daily Regional Freshwater Withdrawal for Coal-Fired Power Generation – 

Case 2 

-5

0

5

10

15

20

25

30

35

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawl, 2005 Incremental Water Withdraw, 2005 - 2030
Freshwater Needs for Thermoelectric Generation, September 2007 

53 

Figure 42 – Average Daily Regional Freshwater Withdrawal for Coal-Fired Power Generation – 

Case 3 

-5

0

5

10

15

20

25

30

35

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawl, 2005 Incremental Water Withdraw, 2005 - 2030

Figure 43 – Average Daily Regional Freshwater Withdrawal for Coal-Fired Power Generation – 

Case 4 

-5

0

5

10

15

20

25

30

35

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawl, 2005 Incremental Water Withdraw, 2005 - 2030
Freshwater Needs for Thermoelectric Generation, September 2007 

54 

Figure 44 – Average Daily Regional Freshwater Withdrawal for Coal-Fired Power Generation – 

Case 5 

-10

-5

0

5

10

15

20

25

30

35

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Withdrawals (BGD)

Water Withdrawl, 2005 Incremental Water Withdraw, 2005 - 2030

Figure 45 – Average Daily Regional Freshwater Consumption for Coal-Fired Power Generation – 

Case 1 

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030
Freshwater Needs for Thermoelectric Generation, September 2007 

55 

Figure 46 – Average Daily Regional Freshwater Consumption for Coal-Fired Power Generation – 

Case 2 

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030

Figure 47 – Average Daily Regional Freshwater Consumption for Coal-Fired Power Generation – 

Case 3 

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030
Freshwater Needs for Thermoelectric Generation, September 2007 

56 

Figure 48 – Average Daily Regional Freshwater Consumption for Coal-Fired Power Generation – 

Case 4 

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030

Figure 49 – Average Daily Regional Freshwater Consumption for Coal-Fired Power Generation – 

Case 5 

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

ECAR

ERCOT

MAAC

MAIN

MAPP

NPCC/NY

NPCC/NE

FRCC

SERC

SPP

WECC/NWPP

WECC/RM

WECC/CA

Consumption (BGD)

Water Consumption, 2005 Incremental Water Consumption, 2005 - 2030
Freshwater Needs for Thermoelectric Generation, September 2007 

57 

Case 4 

Conventional coal generation freshwater withdrawal and consumption levels for Case 4 

are less than the respective values from Case 2. By 2030, freshwater withdrawal is 

projected to be slightly less in Case 4 compared to Case 2 – 93.0 BGD vs. 92.1 BGD 

(Figure 43). Freshwater consumption is projected to be approximately 8% less – 3.8 

BGD in Case 4 vs. 3.5 BGD in Case 2 (Figure 48). On a regional basis, freshwater 

withdrawal and consumption increases and decreases are also similar to Case 2. 

Case 5 

By 2030, total conventional coal generation freshwater withdrawal is projected to be 

approximately 17% less in Case 5 compared to Case 2 – 76.9 BGD vs. 93.0 BGD – while 

consumption is projected to be approximately 5% more – 4.0 BGD in Case 5 vs. 3.8 

BGD in Case 2. On a regional basis, freshwater withdrawal increases very slightly in the 

ERCOT , FRCC, WECC/NWPP, WECC/RM regions; and decreases significantly in the 

NPCC/NY (23%), NPCC/NE (23%), ECAR (21%), and MAAC (20%) regions (Figure 

44). Freshwater consumption increases in all of the regions, with relatively large 

percentage increases occurring in the NPCC/NE (201%), NPCC/NY (366%), ECAR 

(34%), MAIN (151%), SERC (32%), FRCC (250%), ERCOT (115%), WECC/RM 

(130%), WECC/NWPP (111%), and WECC/CA (577%) regions (Figure 49). 

Carbon Capture Deployment Analysis 

The carbon capture deployment analysis uses the same five cases for the types of cooling 

systems for the new plant additions. All water withdrawal and consumption results in 

this analysis are for freshwater. The analysis also assumes three scenarios for the 

additions required to supplement the decrease in capacity for the PC plants retrofitted 

with carbon capture technologies as described in the Assumptions and Methodology

section of this report. The projected results of all of the scenarios for PC plants with 

scrubbers and IGCC plants with 90% CO2 capture, for the year 2030, show an increase in 

water withdrawal and consumption over the non-capture scenario. Figure 50 and Figure 

52 show the results for the five cases and 3 scenarios with respect to all thermoelectric 

generation. 

Figure 50 shows the additional amount of water withdrawal if all of the forecasted PC 

plants with scrubbers and IGCC plants were to deploy carbon capture technologies, 

compared to all thermoelectric plants without carbon capture technologies for the 

projected year 2030. The case 2 data in Figure 50 shows that in 2030, 143.8 BGD of 

water withdrawal is projected for all thermoelectric plants without carbon capture 

deployment. Scenario 1 shows by retrofitting carbon capture technologies to the existing 

scrubbed coal-fired fleet and deploying capture ready technologies to all new additions, 

an additional 4.1 BGD would be required, resulting in a total of 147.9 BGD. If Scenario 

2 is applied, building all IGCC plants for the replacement power lost to the retrofits, 0.7 

BGD would be added to Scenario 1, resulting in a total of 148.6 BGD. Scenario 3, 

building all PC supercritical plants for the replacement power, would add 1.9 BGD to 

Scenario 1 resulting in a total of a 149.8 BGD withdrawal. Since recirculating cooling 
Freshwater Needs for Thermoelectric Generation, September 2007 

58 

systems are used in all three scenarios, water withdrawal is low relative to water 

consumption. 

Figure 50 - Thermoelectric Generation with Additional Water Withdrawal for PC and IGCC 

Carbon Capture Deployment for Year 2030 

0

40

80

120

160

200

Water Withdrawal 

(BGD)

12345

Case

Scenario 3

Scenario 2

Scenario 1

All Non-Capture

Thermoelectric Plants

Figure 51 illustrates the breakdown of Scenario 1 and a closer look at the other two 

scenarios for Case 2. The bottom section of the blue bars represent the additional water 

withdrawal required for the existing PC retrofits, 2.6 BGD. The top section of the blue 

bars represent the additional water withdrawal required for the carbon capture 

technologies of the new PC and IGCC capacity, 1.4 BGD. Therefore, Scenario 1 would 

require a total of 4.0 BGD. Scenario 2 would include the 4.0 BGD plus an additional 0.7 

BGD of water withdrawal for the new IGCC plants built to replace the power lost to the 

retrofits for a total 4.7 BGD. Scenario 3 is similar to Scenario 2 except instead of IGCC 

plants built to make up the power loss, supercritical PC plants would be built. These 

supercritical PC plants would require 1.9 BGD water withdrawal and combined with the 

Scenario 1 demand, would require a total 5.9 BGD. 

Figure 51 – Additional Water Withdrawal of CO2 Capture Scenarios – Case 2 

0

1

2

3

4

5

6

7

Water Withdrawal 

(BGD)

123

Scenario

New PC Replacement

Power

New IGCC Replacement

Power

New PC and IGCC with

CO2

Existing PC Retrofits

with CO2
Freshwater Needs for Thermoelectric Generation, September 2007 

59 

Figure 53 shows the additional amount of water consumption if all of the forecasted PC 

with scrubbers and IGCC plants were to deploy carbon capture technologies compared to 

all thermoelectric plants without carbon capture technologies. The Case 2 data in Figure 

52 shows that in 2030, 8.2 BGD of water consumption is projected for all thermoelectric 

plants without carbon capture deployment. Scenario 1 shows by deploying carbon 

capture technologies to the scrubbed coal-fired fleet, an additional 2.9 BGD would be 

required, resulting in a total of 11.1 BGD. If Scenario 2 is applied, 0.6 BGD would be 

added to Scenario 1, resulting in a total of 11.7 BGD. Scenario 3 would add 1.4 BGD to 

Scenario 1 resulting in a total water consumption of 12.5 BGD for Scenario 3. 

Figure 52 - Thermoelectric Generation with Additional Water Consumption for PC and IGCC 

Carbon Capture Deployment for Year 2030 

0

2

4

6

8

10

12

14

Water Consumption 

(BGD)

12345

Case

Scenario 3

Scenario 2

Scenario 1

All Non-Capture

Thermoelectric Plants

Figure 53 illustrates the breakdown of Scenario 1 and a closer look at the other two 

scenarios for Case 2. The bottom section of the blue bars are the additional water 

consumption required for the existing PC retrofits, 1.8 BGD. The top section of the blue 

bars is the additional water consumption required for the carbon capture technologies of 

the new PC and IGCC capacity, 1.1 BGD. Therefore, Scenario 1 would require at total of 

2.9 BGD. Scenario 2 would include the 2.9 BGD plus an additional 0.6 BGD of water 

consumption for the new IGCC plants built to replace the power lost to the retrofits for a 

total 3.5 BGD. Scenario 3 is similar to Scenario 2 except instead of IGCC plants built to 

make up the power loss, supercritical PC plants would be built. These supercritical PC 

plants would require 0.7 BGD water consumption and combined with the Scenario 1 

demand, would require a total 4.3 BGD. 
Freshwater Needs for Thermoelectric Generation, September 2007 

60 

Figure 53 - Additional Water Consumption of CO2 Capture Scenarios – Case 2 

0

1

2

3

4

5

Water Consumption 

(BGD)

123

Scenario

New PC Replacement

Power

New IGCC Replacement

Power

New PC and IGCC with

CO2

Existing PC Retrofits

with CO2

Figure 54 and Figure 55 show the water withdrawal and consumption for the five cases 

and three scenarios with respect to just the coal-fired fleet 

Figure 54 - PC and IGCC Generation with Additional Water Withdrawal for PC and IGCC Carbon 

Capture Deployment for Year 2030 – 

1 2 3 4 5

Scenario 2

Non CO2 

Capture

0

20

40

60

80

100

Water Withdrawal 

(BGD)

Case

Non CO2 Capture

Scenario 1

Scenario 2

Scenario 3
Freshwater Needs for Thermoelectric Generation, September 2007 

61 

Figure 55 - PC and IGCC Generation with Additional Water Consumption for PC and IGCC 

Carbon Capture Deployment for Year 2030 

1 2 3 4 5

Scenario 3

Scenario 2

Scenario 1

Non CO2 

Capture 0

2

4

6

8

10

Water Consumption 

(BGD)

Case

The results for the three scenarios for total water withdrawal and consumption for PC 

plants with scrubbers and IGCC plants with carbon capture technologies are presented in 

Table 11 and Table 12 respectively. The baseline values listed in the tables are used as a 

reference for non-capture PC plants with scrubbers and IGCC plants. 

Table 11 – Scenarios for Year 2030 Total Water Withdrawal for Scrubbed PC and IGCC with CO2

Capture and No Capture Baseline Reference 

Water Withdrawal (BGD) 

Scenario Case 1 Case 2 Case 3 Case 4 Case 5 

No CO2 Capture Baseline 81.3 71.6 71.5 71.2 60.6 

1. Conservative 

Retrofit load not accounted for

85.3 75.7 75.2 74.3 64.7 

2. IGCC Recirculating Additions 

Fixed Additions accounts for retrofit load

86.1 76.4 75.9 74.9 65.4 

3. Supercritical Recirculating Additions 

Fixed Additions accounts for retrofit load

87.3 77.6 76.9 76.4 66.6 
Freshwater Needs for Thermoelectric Generation, September 2007 

62 

Table 12 – Scenarios for Year 2030 Total Water Consumption for Scrubbed PC and IGCC with CO2

Capture and No Capture Baseline Reference 

Water Consumption (BGD) 

Scenario Case 1 Case 2 Case 3 Case 4 Case 5 

No CO2 Capture Baseline 3.6 3.8 3.7 3.5 4.0 

1. Conservative 

Retrofit load not accounted for

6.5 6.7 6.5 5.6 6.8 

2. IGCC Recirculating Additions 

Fixed Additions accounts for retrofit load

7.1 7.3 7.0 6.1 7.4 

3. Supercritical Recirculating Additions 

Fixed Additions accounts for retrofit load

7.9 8.1 7.8 6.8 8.3 

Depending on the cases and scenarios for plant additions, deploying carbon capture 

technologies in PC plants with scrubbers and IGCC plants in the year 2030 would 

increase water withdrawal anywhere from 4.1 BGD to 6.0 BGD where the average 

increased water withdrawal for all scenarios and cases is 7%. The increase in water 

consumption could range from 2.2 BGD to 4.3 BGD and the average increased water 

consumption for all scenarios and cases is 90%. 

Comparison of 2006 & 2007 Study Projections 

Unlike the previous comparison of the 2004 and 2006 water needs analyses which had 

fundamentally different analytical approaches, the 2006 and 2007 analyses used the same 

methodologies. The 2006 and 2007 studies provided a bottoms-up analysis as opposed to 

the 2004 study which provided a top-down analysis. The majority of the changes in the 

2007 results are the results of EIA’s AEO 2007 data compared to the 2006 data. 

The 2006 and 2007 water needs analyses evaluated the same five Cases. Table 13 

presents the difference in water withdrawal and consumption for the 2007 update 

compared to the 2006 report at the national level. 

Table 14 Table 14shows the percent changes from the 2006 results. Overall, there are 

many parameters that affected the results. The EIA’s AEO 2007 forecast estimates U.S. 

thermoelectric generating capacity will grow from approximately 708.7 GW in 2005 to 

861.7 in 2030, compared to the AEO 2006 forecast which was 704 GW in 2005 to 872 

GW in 203016. The AEO 2007 data forecasts less thermoelectric additions and fewer 

retirements than AEO 2006. AEO 2007 projects a greater net generation capacity for all 

thermoelectric plants from 2005 to 2025; except for year 2030 which was 1.2% lower 

compared to the AEO 2006 forecast. On average, AEO 2007 forecasts higher reference 

capacity factors and yearly capacity factors for fossil non-coal and combined cycle 

generation and lower reference capacity factors for unscrubbed coal, scrubbed coal, and 

nuclear generation compared to the AEO 2006 data. These two capacity factors are used 

as a capacity factor ratio, termed the F-factor, which accounts for the growth in 

generation. Further explanation of the F-factor is in Appendix B. Based on the weight of 

the capacity factors, the average trend for the 2007 F-factors is lower than the 2006 Ffactors for fossil non-coal and combined cycle and continues to decrease over the 2005 – 

2030 time period. The 2007 F-factors for unscrubbed coal, scrubbed coal, and nuclear 

are larger than those of the 2006 results. Unscrubbed coal and scrubbed coal F-factors 
Freshwater Needs for Thermoelectric Generation, September 2007 

63 

generally increase over time with the exception of year 2010 compared to the 2006 

analysis. The magnitude of the lower F-factors for the fossil non-coal and combined 

cycle plants is greater than the increased F-factors for unscrubbed coal, scrubbed coal, 

and nuclear. The F-factor affects the amount of water consumed and withdrawn in 

recirculating cooling systems. 

The baseline thermoelectric water withdrawal (year 2005) for the 2007 analysis was 

approximately one-tenth of a percent lower than 2006 analysis, 149.2 BGD for the 2006 

analysis and 149.0 BGD for the 2007 analysis. The percent changes for water 

consumption for year 2005 was 2.3% lower for the 2007 results. Lower water 

withdrawal and consumption for years 2005 and 2010, compared to the 2006 analysis, is 

due to the lower F-factors for combined cycle and the lower forecast of combined cycle 

plant additions for those years. As coal additions increase in 2015 and nuclear in 2020, 

the water withdrawals increase as well, compared to the percent change of the 2006 

analysis. The greatest changes seen with the 2007 analysis compared to the 2006 

analysis are in Case 5. 

The 2007 analysis show the same general trends among the 5 cases as seen in the 2006 

analysis. For cases 2 though 5, withdrawal is expected to decline, and consumption for 

all 5 cases is expected to increase. These results are consistent with current and 

anticipated regulations and industry practice, which favor the use of freshwater 

recirculating cooling systems that have lower withdrawal requirements, but higher 

consumption requirements, than once-through cooling systems. Case 5 provides the most 

extreme water consumption impacts. Converting a significant share of existing oncethrough freshwater power plants to recirculating freshwater plants reduces water 

withdrawal, but increases water consumption. Case 4 indicates that dry cooling could 

have a significant impact on water consumption; compared to Cases 1-3, which have an 

average consumption of 8.1 BGD, Case 4 results in a 4% decline, equivalent to more than 

100 billion gallons per year. 

Table 13 - Results Comparison, Difference from 2006 vs. 2007 Water Needs Analysis 

Difference Between 2006 and 2007 Results (BGD) 

 2005 2010 2015 2020 2025 2030 

Withdrawal -0.2 -0.4 1.4 6.2 8.7 9.5 Case 1 

Consumption -0.1 -0.3 -0.2 -0.3 -0.1 0.0 

Withdrawal -0.2 -0.2 2.4 5.5 6.4 7.5 Case 2 

Consumption -0.1 -0.4 -0.2 -0.3 -0.2 0.0 

Withdrawal -0.2 -0.2 2.5 5.5 6.3 7.5 Case 3 

Consumption -0.1 -0.3 -0.3 -0.2 -0.2 0.0 

Withdrawal -0.2 -0.3 2.3 5.2 8.8 7.3 Case 4 

Consumption -0.1 -0.3 -0.2 -0.3 0.0 0.3 

Withdrawal -0.2 5.6 8.9 13.0 13.2 13.8 Case 5 

Consumption -0.1 -0.4 -0.4 -0.4 -0.3 -0.1 
Freshwater Needs for Thermoelectric Generation, September 2007 

64 

Table 14 - Results Comparison, Percent Changes from 2006 Water Needs Analysis 

Percent Change from 2006 Results 

 2005 2010 2015 2020 2025 2030 

Withdrawal -0.1% -0.3% 1.0% 4.2% 5.8% 6.4% Case 1 

Consumption -2.3% -4.5% -3.1% -3.8% -2.0% -0.2% 

Withdrawal -0.1% -0.1% 1.7% 4.0% 4.6% 5.5% Case 2 

Consumption -2.3% -5.2% -3.3% -3.5% -2.1% 0.3% 

Withdrawal -0.1% -0.1% 1.8% 4.0% 4.6% 5.5% Case 3 

Consumption -2.3% -4.1% -3.7% -3.2% -2.3% -0.2% 

Withdrawal -0.1% -0.2% 1.6% 3.8% 6.6% 5.4% Case 4 

Consumption -2.3% -4.5% -3.0% -3.5% 0.1% 3.6% 

Withdrawal -0.1% 4.1% 7.2% 11.4% 12.1% 13.3% Case 5 

Consumption -2.3% -5.5% -5.1% -5.4% -3.3% -1.6% 

Conclusions

Population shifts, increasing power demand, and greater competition for water resources 

has heightened interest in the link between energy and water. The EIA projects about a 

22% increase in total generating capacity by 2030 compared to 2005. Of the 258.2 GW 

of new capacity projected to come on-line by 2030, more than 192 GW will be 

thermoelectric generation. 

On a national basis, this analysis indicates that the potential impacts on future freshwater 

withdrawals to meet forecasted increases in electricity generating capacity would be 

relatively low, with most cases exhibiting a decrease in daily withdrawals. 

To operate the 192.6 GW of new thermoelectric generating capacity in 2030: 

• Freshwater withdrawal requirements will decrease by 3% to 21% compared to 

freshwater withdrawals in 2005 

• Freshwater consumption in 2030 will increase by 30% to as much as 50% 

compared to 2005 

Similar trends in freshwater withdrawal and consumption are projected for the additional 

coal-based generating capacity that will come on line by 2030: 

• Freshwater withdrawal requirements will range from a 17% decrease to an 11% 

increase 

• Freshwater consumption requirements will increase ranging from 44% to a 65% 

 While thermoelectric water consumption could increase by as much as 50%, it is still 

relatively small compared to other sectors, specifically irrigation/agriculture as seen in 

Appendix A. 
Freshwater Needs for Thermoelectric Generation, September 2007 

65 

The regional component of the 2007 water needs analysis revealed some significant 

differences from the national averages, reflecting recent U.S. population shifts. Regions 

with strong population growth, such as the southeast and southwest, exhibit high growth 

in water consumption requirements, while regions with minimal to modest population 

growth, such as the midwest and mid-Atlantic, exhibit modest growth in water 

consumption requirements. EIA projects a 58% increase in thermoelectric capacity by 

2030 for the western United States and a 30% increase in the southeast compared to the 

22% increase nationally. These increases in projected capacity will occur in regions of 

the United States that are challenged in terms of both current and future availability of 

freshwater. For example, consider Case 2, a plausible future cooling system scenario that 

assumes all capacity additions use freshwater and wet recirculating cooling. 

National percent changes indicate between 2005 and 2030 (Case 2) 

• water withdrawal will fall by 3.5% 

• water consumption will rise by 39% 

Regional percent changes indicate between 2005 and 2030 (Case 2) 

• Water withdrawal ranges from a 28% increase in Florida to a 24% decline in Texas 

• Water consumption increases in all regions 

o Biggest gains come in California (280%), Florida (260%), New York 

(467%), Northwest (85%), and the Rocky Mountain/desert southwest 

region (85%). 

The thermoelectric power generation sector will remain a considerable water consumer 

for the foreseeable future. While national water withdrawals are projected to decline 

slightly over the 25-year time period evaluated in this analysis, the amount of water 

withdrawal is huge, on the order of 118 to 158 billion gallons per day. On a consumption 

basis, although the magnitude is much less than that for withdrawal, the trend is steadily 

upward, regardless of the case considered. National water consumption is expected to 

grow from 6.2 billion gallons per day in 2005 to between 8 and 9 billion gallons per day 

by 2030. In the face of growing competition for water resources – particularly in the arid 

West and Southwest, and in the expanding Southeast – regional and national efforts to 

reduce water withdrawal and consumption for thermoelectric power plants are expected 

to intensify. 

Assuming current carbon capture technologies are implemented at coal-fired PC plants in 

the future, an increased amount of water usage will to be required. EIA’s current 

forecasts show that coal-fired generation will play a large part in our Nation’s electric 

generation portfolio. The water use for the carbon capture section of this analysis is a 1st

order view to get a general idea of how the implementation of these technologies will 

affect the water withdrawal and consumption. Depending on the cases and scenarios for 

plant additions, deploying carbon capture technologies in PC plants with scrubbers and 

IGCC plants in the year 2030 would increase water withdrawal anywhere from 4.1 BGD 

to 6.0 BGD where the average increased water withdrawal for all scenarios and cases is 

7%. The increase in water consumption could range from 2.2 BGD to 4.3 BGD and the 
Freshwater Needs for Thermoelectric Generation, September 2007 

66 

average increased water consumption for all scenarios and cases is 90%. As seen in the 

past with other emission control technologies, R&D efforts will promote improved 

efficiencies with current technologies and develop new emerging technologies, therefore 

lowering the water demands. 
Freshwater Needs for Thermoelectric Generation, September 2007 

A-1 

Appendix A 

Energy-Water Issues 

Supplemental Information

Water Availability

In 2006, RDS contacted state government water monitoring agencies inquiring if water 

availability in general is a concern in their state. Of the 33 states that responded, 58% of 

states said that yes, water availability is a concern. An additional 15% said that water 

availability varies within the state, with only some regions having water supply issues. 

Another 12% responded that water availability had not been of great concern in the past, 

but has recently been becoming more critical. 

Water availability issues are not limited to the western United States. State government 

water monitoring contacts in Alabama, Florida, Hawaii, Illinois, Louisiana, Missouri, 

South Carolina, and Virginia indicated that water availability is generally a concern in 

their state or has become more of a concern in recent years. A February 2006 article in 

the Baltimore Sun17 describes the difficulties of several communities in Maryland facing 

water shortages, where “growing towns in Carroll and Frederick counties have been 

forced to curtail development – either voluntarily or under orders from the state – because 

their growth was outstripping water supplies.” In addition, the article states that in 

“Southern Maryland, the state’s fastest-growing region, groundwater levels are dropping 

an average of 1 to 2 feet a year.” 

Competing Water Uses

Concerns over limited water quantities are not restricted to thermoelectric generation. 

According to USGS, 346 billion gallons of freshwater were withdrawn per day in the 

United States in the year 2000.4 The largest use, agricultural irrigation, accounted for 

40% of freshwater withdrawn (see Figure A-1). 

Figure A-1 - Percent of freshwater withdrawal by use category 

U.S. Freshwater Withdrawal (2000)

Thermoelectric, 39%

Public Supply, 13% Domestic, 1%

Irrigation, 40%

Livestock, 1%

Aquaculture, 1%

Industrial, 5%

Mining, 1%
Freshwater Needs for Thermoelectric Generation, September 2007 

A-2 

The second largest use, thermoelectric generation, withdrew 136 billion gallons per day 

(BGD), followed by public supply, industrial uses, aquaculture, domestic use, mining, 

and livestock. Interestingly, thermoelectric generation withdrew the largest amount of 

saline water, 60 BGD (96% of all saline withdrawn). Withdrawal of saline water (and 

other non-traditional waters) reduces the strain on freshwater supplies and is one research 

area facilitated by the IEP program.

USGS estimates for freshwater consumption for the year 1995 (the most recent year for 

which this data is available) is presented in Figure A-2.5 Freshwater consumption for 

thermoelectric purposes appears low (only 3%) when compared to other use categories 

(irrigation was responsible for 81% of water consumed). However, even at 3% 

consumption, over 3 BGD were consumed. As a result of growing public pressures to 

withdraw less water, coupled with requirements under Section 316(b) of the Clean Water 

Act, consumption will likely increase significantly due to greater use of closed-loop 

cooling systems that consumes far more water than once-through cooling systems due to 

evaporation losses. 

Figure A-2 - Percent of freshwater consumption by use category

U.S. Freshwater Consumption (1995)

Thermoelectric, 3%

Mining, 1%

Industrial, 3%

Livestock, 3%

Irrigation, 81%

Domestic, 6%

Commercial, 1%

In addition to the water uses described above, increased value is being placed on instream freshwater uses, consisting mainly of habitat/species protection and recreational 

uses. In-stream uses will require a minimum flow rate or depth to be maintained in water 

bodies. 

Because freshwater supply is limited, choices will have to be made regarding withdrawal 

and consumption of this natural resource. Water availability and its withdrawal and 

consumption are top priorities on the public agenda in many nations throughout the 

world. It is likely that the issue will also filter to the top of the U.S. public agenda in the 

near future. In water-stressed areas of the country, power plants will increasingly 

compete with other water users. Agriculture and public supply will most likely be the 

greatest competitors due to their large water withdrawal. As with all resources, tradeoffs 

will occur, and concerns will increasingly be raised over which use is more important: 

water for drinking and personal use, growing food, or energy production. 
Freshwater Needs for Thermoelectric Generation, September 2007 

A-3 

Regulatory Impacts on Water Withdrawal and Consumption

The power industry must comply with a variety of local, state and federal regulations 

pertaining to water acquisition, use, and quality. In considering long-term water 

withdrawal and consumption patterns in the power sector, the cooling water intake 

structure regulations established under the Clean Water Act, Section 316(b) will likely 

have the greatest impact. Designed to protect aquatic life from inadvertently being killed 

by intake structures at power stations and certain manufacturing facilities, Section 316(b) 

requires EPA to ensure that the “location, design, construction and capacity of cooling 

water intake structures reflect the best technology available for minimizing adverse 

environmental impact.” 

EPA divided its 316(b) rulemaking into three phases: Phase I, completed in late 2001, 

applies to new facilities; Phase II, completed in early 2004, applies to large existing 

power facilities; and Phase III, due to be finalized in 2006, applies to existing 

manufacturing facilities. The regulations establish performance standards for cooling 

water intake structures based on impingement mortality and entrainment (IM&E) 

impacts. A minimum level of IM&E reduction is required based on the type of water 

body a given facility accesses for cooling water. Compliance with 316(b) is coordinated 

through the individual states’ NPDES (National Pollutant Discharge Elimination System) 

permitting program. 

The largest design impact of 316(b) compliance is that most new power plants will have 

to use closed-loop, recirculating cooling systems or dry (air-cooled) systems. Open-loop 

systems are strongly discouraged unless the permit applicant can demonstrate that 

alternative IM&E measures can provide a reduction level comparable to that achieved 

through closed-loop cooling or that the compliance costs, air quality impacts, and/or 

energy generation impacts would outweigh the IM&E benefits and justify an open-loop 

system. Because 316(b) portends a greater reliance on closed-loop cooling systems, 

water withdrawal and consumption patterns for the thermoelectric power sector are 

destined to change over time. Even accounting for significant thermoelectric capacity 

additions, water withdrawal levels will likely remain relatively constant. Water 

consumption, on the other hand, is expected to increase substantially since closed-loop 

cooling systems consume more water, due to evaporation, than open-loop systems. 

Existing and future air quality regulations will also affect water withdrawal and 

consumption patterns, although to a lesser extent than cooling water regulations. Tighter 

emission levels for sulfur dioxide, for example, have sparked a mini-boom in the flue gas 

desulfurization (FGD) market. The size of the U.S. FGD market is expected to increase 

by more than 100,000 megawatts (MW) over the next 10 years. Although FGD water 

requirements are a fraction of those required for cooling purposes, FGD units require a 

significant amount of water to produce and handle the various process streams (limestone 

slurry, scrubber sludge, etc.). Makeup water requirements for the FGD island at a 

nominal 550 MW subcritical coal-fired power plant are about 570 gpm, versus about 

9,500 gpm for cooling water makeup.18 Nonetheless, the additional FGD systems 

coming online within the next decade will place a greater strain on water supplies. 
Freshwater Needs for Thermoelectric Generation, September 2007 

A-4 

Notably, semi-dry flue gas desulfurization systems are available that substantially reduce 

water requirements for SO2 control, and these systems are in commercial application at 

numerous plants, many in arid environments. 

Several other regulatory actions warrant attention because of their potential impact on 

water withdrawal and consumption. Under section 303(d) of the 1972 Clean Water Act, 

states, territories, and authorized tribes are required to develop a list of impaired waters 

not meeting water quality standards and then establish total maximum daily loads 

(TMDL) for these waters. A TMDL specifies the maximum amount of a pollutant that a 

waterbody can receive and still meet water quality standards, and allocates pollutant 

loadings among point and nonpoint pollutant sources. TMDL requirements could 

potentially constrain a power plant’s ability to discharge cooling water, as well as trace 

metals and other pollutants from flue-gas cleanup byproducts, into a water body if the 

water body is impaired. The power plant may then be required to seek an alternate water 

source or install additional water treatment equipment. 

The current debate over global climate change and carbon dioxide (CO2) emissions could 

also potentially impact the water resource situation. If power plants are ultimately 

required to implement carbon separation and sequestration technologies to comply with 

future regulations, additional water may be needed for certain process steps and 

groundwater could be impacted by CO2 sequestration (in a manner similar to produced 

water from oil and gas recovery applications). On the other hand, water could potentially 

be recovered from the CO2 stream prior to dry pumping for sequestration or reclaimed 

from produced waters due to underground displacement. A detailed analysis would be 

required to delineate the net water withdrawal and consumption associated with CO2

separation and sequestration and is outside the scope of this study. 

Legislative Activities

The Energy Policy Act of 2005 (Title IX, Subtitle G − Science, Section 979) directs the 

DOE to address energy-water nexus issues and assess the effectiveness of existing 

Federal programs to address energy-water related issues. The direction is for a program 

of research, development, demonstration, and commercial application to: 1) address 

energy-related issues associated with provision of adequate management, and efficient 

use of water; 2) address water-related issues associated with the provision of adequate 

supplies, optimal management, and efficient use of energy; and 3) assess the 

effectiveness of existing programs within the Department and other Federal agencies to 

address these energy and water related issues. 

An amendment to the Energy Policy Act, the Energy-Water Efficiency and Supply 

Technology Bill, was originally introduced in 2004 and has gone through two revisions. 

The current version of the bill would allocate $5 million for the first year and “such sums 

as are necessary for each fiscal year thereafter.” The bill would instruct the Secretary of 

Energy to “establish a national program for the research, development, demonstration, 

and commercial application of economically viable and cost-effective water supply 

technologies.” 
Freshwater Needs for Thermoelectric Generation, September 2007 

A-5 

Drought Conditions

A Government Accountability Office (GAO) report19 prepared in 2003 addressed the 

issue of freshwater supply at the state level. The report indicated that under normal 

rainfall conditions, state water managers in 36 states anticipated shortages in localities, 

regions, or even statewide in the next 10 years (2003 – 2013). The report goes on to say 

that “drought conditions will exacerbate shortage impacts.” 

During the summer of 2005, a joint effort between the Department of the Interior (DOI) 

and the Department of Agriculture (USDA) created Interagency Drought Action Teams 

to coordinate relief efforts in communities in western states facing droughts. A DOI 

report20 about the action teams quotes Secretary (of the Interior) Norton, “Much of the 

Pacific Northwest has been hard hit by drought this year.” 

Power Generation Facility Siting

Power generation facilities will have increasing difficulties siting new plants due to water 

concerns. Concurrently, existing plants will be under increasing pressure to reduce their 

water withdrawal and consumption. In 2006, RDS contacted state government water 

monitoring agencies inquiring if there is a limit to freshwater withdrawal and/or 

consumption by thermoelectric plants in their state. Of the 33 states that responded, 24% 

indicated that plants must either have a senior water right, or purchase such a water right 

from an entity willing to sell it. Another 18% indicated that limitations are imposed 

when water levels fall below the protect flow level and/or in times of water shortage. An 

additional 18% of states responded that water withdrawal and consumption varies 

regionally across the state, with some areas having no limit but other areas that are water 

sparse or over-allocated requiring water rights or special permits. The number of states 

with over-allocated water resources is expected to increase over time. 

Concern about water supply, expressed by state regulators, local decision-makers, and the 

general public, is already impacting power projects across the United States. For 

example, in March 2006, an Idaho state House committee unanimously approved a twoyear moratorium on construction of coal-fired power plants in the state based on 

environmental and water supply concerns.21 Arizona recently rejected permitting for a 

proposed power plant because of concerns about how much water it would withdraw 

from a local aquifer.22 In early 2005, Governor Mike Rounds of South Dakota called for 

a summit to discuss drought-induced low flows on the Missouri River and the impacts on 

irrigation, drinking-water systems, and power plants.23 A coal-fired power plant to be 

built in Wisconsin on Lake Michigan has been under attack from environmental groups 

because of potential effects of the facility’s cooling-water-intake structures on aquatic 

life.24 In February 2006, Diné Power Authority reached an agreement with the Navajo 

Nation to pay $1,000 per acre foot and a guaranteed minimum total of $3 million for 

water for its proposed Desert Rock Energy Project.25 In an article discussing a 1,200 

MW proposed plant in Nevada, opposition to the plant stated, “There’s no way Washoe 

County has the luxury anymore to have a fossil-fuel plant site in the county with the 

water issues we now have. It’s too important for the county’s economic health to allow 

water to be blown up in the air in a cooling tower.”26
Freshwater Needs for Thermoelectric Generation, September 2007 

B-1 

Appendix B 

Water Needs Analysis Methodology 

The purpose of this analysis is to update a 2004 National Energy Technology Laboratory 

(NETL) study to estimate freshwater needs to meet future year thermoelectric generation 

capacity requirements. The 2006 and 2007 analyses use a more detailed analytical 

approach and incorporate data and projections from the Energy Information 

Administration’s Annual Energy Outlook yearly publications. Table B-1 summarizes the 

specific items that are updated in the 2006/2007 Water Needs Analyses. The additional 

level of detail and resolution included in the 2006/2007 analyses required a modified 

methodology from that used in the 2004 analysis. 

Table B-1 - U.S. Power Generation Industry Water Withdrawal and Use Analysis – Comparison of 

Assumptions and Methodologies 

Item 2004 Analysis 2006/2007 Analysis 

Capacity/Generation 

Projections AEO 2004 AEO 2006/2007 

Geographical Breakdown National National and NERC region 

Cooling Water Source 

Breakdown Freshwater and Saline Freshwater and Saline 

Cooling Water System Type Once-through and wet 

recirculating 

Once-through and recirculating 

(dry, wet, and cooling pond) 

Generation Type Breakdown Total thermoelectric and coal 

Total thermoelectric and coal, 

nuclear, non-coal steam, and natural 

gas combined cycle 

Final Year of Projection 2025 2030 

Cases Six cases representing upper 

and lower bounds 

Five cases with conservative 

assumptions 

Water Use Scaling Factors – 

Geographic Coverage National NERC region with adjustment for capacity factor increase 

Water Use Scaling Factors – 

Coal Plant Design Not included 

Boiler type – subcritical or 

supercritical 

FGD type – wet, dry, or none 

Additional Water Uses for CO2

Capture Plants Not included 

2006 Analysis – Not included 

2007 Analysis – Included for PC 

and IGCC Plants 

Figure B-1 provides a flowchart depiction of the methodology used to conduct the 

analysis. The five-step approach represents a refined and more robust methodology than 

that used in the 2004 Water Needs Analysis. Each step in the process is described below. 
Freshwater Needs for Thermoelectric Generation, September 2007 

B-2 

Figure B-1 - Methodology for the 2006/2007 Water Needs Analysis 

Develop 

model plants 

to represent 

existing 

thermoelectric fleet

Calculate 

water 

withdrawal 

and 

consumption 

factors

Quality 

control and 

model 

validation

Develop 

future 

cases to 

evaluate

Calculate 

regional 

withdrawal 

and 

consumption 

to 2030

Step 1 Step 2 Step 3 Step 4 Step 5

Step 1: Develop model plants 

To obtain the resolution desired for this analysis, water withdrawal and consumption 

factors were determined for a large number of plant configurations, based on location, 

generation type, cooling water source, cooling system type, and where applicable, boiler 

type and type of flue gas desulfurization (FGD) system. The existing thermoelectric fleet 

was segregated into numerous configurations, called “model plants” using data contained 

in several sources: the NETL Coal Plant Database, EIA-767, and EIA-860. Water 

withdrawal and consumption factors were calculated for each model plant using the 

available data and then used in conjunction with projections from AEO 2006/2007 to 

provide an estimate of future water withdrawal and consumption for various cases. 

The model plant derivation process is detailed below. 

NERC Regions 

Cooling water needs will vary by region due to climatic variations and availability of 

cooling water. Performing the water needs analysis on a regional level, therefore, 

provides a more accurate estimate of cooling water trends than a higher-level analysis. 

To accomplish this, the 13 NERC regions (excluding Alaska and Hawaii) were integrated 

into the NETL Coal Plant Database from the EIA-860 database. 

Thermoelectric Generation Type 

Water withdrawal and consumption factors were determined for thermoelectric power 

plants: coal, nuclear, oil, natural gas and the steam portion of gas-fired combined cycles. 

However, more detailed effort was expended in determining water factors for coal-fired 

power plants. The analysis doe not include non-thermoelectric plants such as combustion 

turbines, renewable generations, etc. 

 

Individual water use estimates were developed for the following thermoelectric 

generation types: 

i. Coal 

ii. Nuclear 

iii. Non-Coal Fossil 

iv. Combined Cycle 
Freshwater Needs for Thermoelectric Generation, September 2007 

B-3 

Model plants for coal in each NERC region were developed using the following 

hierarchy: 

Cooling Water Type (Freshwater/Saline) 

↓

Cooling Water System Type (Once-Through, Wet Recirculating, Dry Recirculating, 

Cooling Ponds) 

↓

Boiler Type (Subcritical, Supercritical) 

↓

FGD Type (Wet, Dry, None) 

Using this hierarchy, a total of 30 model plants are possible for coal in each regione

: 

1. Freshwater, once-through, subcritical, wet FGD 

2. Freshwater, once-through, subcritical, dry FGD 

3. Freshwater, once-through, subcritical, no FGD 

4. Freshwater, once-through, supercritical, wet FGD 

5. Freshwater, once-through, supercritical, dry FGD 

6. Freshwater, once-through, supercritical, no FGD 

7. Freshwater, recirculating, subcritical, wet FGD 

8. Freshwater, recirculating, subcritical, dry FGD 

9. Freshwater, recirculating, subcritical, no FGD 

10. Freshwater, recirculating, supercritical, wet FGD 

11. Freshwater, recirculating, supercritical, dry FGD 

12. Freshwater, recirculating, supercritical, no FGD 

13. Freshwater, cooling pond, subcritical, wet FGD 

14. Freshwater, cooling pond, subcritical, dry FGD 

15. Freshwater, cooling pond, subcritical, no FGD 

16. Freshwater, cooling pond, supercritical, wet FGD 

17. Freshwater, cooling pond, supercritical, dry FGD 

18. Freshwater, cooling pond, supercritical, no FGD 

19. Saline, once-through, subcritical, wet FGD 

20. Saline, once-through, subcritical, dry FGD 

 

e

 According to the hierarchy presented, 36 model plant combinations are possible. Six of these 

combinations would be configured with saline cooling ponds. Such a cooling water source is technically 

impractical and, therefore, not included in this analysis. 
Freshwater Needs for Thermoelectric Generation, September 2007 

B-4 

21. Saline, once-through, subcritical, no FGD 

22. Saline, once-through, supercritical, wet FGD 

23. Saline, once-through, supercritical, dry FGD 

24. Saline, once-through, supercritical, no FGD 

25. Saline, recirculating, subcritical, wet FGD 

26. Saline, recirculating, subcritical, dry FGD 

27. Saline, recirculating, subcritical, no FGD 

28. Saline, recirculating, supercritical, wet FGD 

29. Saline, recirculating, supercritical, dry FGD 

30. Saline, recirculating, supercritical, no FGD 

Similar model plants were developed for nuclear, non-coal fossil, and combined cycle, 

but only broken down by cooling water type (freshwater vs. saline) and cooling water 

system type (once-through, recirculating, cooling pond). 

Step 2: Calculate water withdrawal and consumption factors 

For each model plant defined in Step 1, water withdrawal and consumption factors were 

calculated using the data sources outlined above. 

Coal

For coal, the water withdrawal and consumption factors were based on the sum of three 

components: 1) boiler make-up water; 2) FGD make-up water; and 3) cooling water. 

The boiler make-up water component at a coal plant depends on the type of boiler – 

either subcritical or supercritical. The boiler make-up water factors were calculated using 

water balance data contained in Parsons’ “Power Plant Water Consumption Study” 

conducted for NETL in August 2005. Separate values were determined for subcritical 

and supercritical plant configurations, but the values were fixed for all regions, water 

source, cooling type, and FGD type. 

The FGD make-up water component depends on the type of FGD system – either wet or 

dry. Dry FGD systems require much less water than wet FGD systems, for example, so 

different factors must be used. The FGD make-up water factors were calculated using 

material balance data contained in Carnegie Mellon University’s Integrated 

Environmental Control Model (IECM). Separate values were determined for subcritical 

and supercritical plant configurations, but the values were fixed for all regions, water 

source, and cooling type. 

The cooling water component for each model plant was calculated by compiling data 

from the NETL Coal Power Plant Database and EIA-860 for water withdrawal, water 

consumption, and summer capacity. Average water withdrawal (gal/hr), average water 

consumption (gal/hr), and summer capacity were used to calculate average withdrawal 

and consumption scaling factors (gal/kWh) for each model plant in each of the NERC 

regions. The power plant capacity data contained in the NETL database consists of 
Freshwater Needs for Thermoelectric Generation, September 2007 

B-5 

nameplate MW capacity taken from the EIA-767 report. However, the AEO projections 

are based on summer capacity. Therefore, summer capacity (MW) data was obtained 

from the EIA-860 report to calculate the scaling factors. The following methodology was 

used to calculate the average cooling water withdrawal and consumption factors for each 

type of cooling water system: 

o Once-through systems: To maximize plant efficiency during partial load 

operation, power plant operators normally maintain cooling water flow through 

the condenser at full load design rates. Therefore, the cooling water withdrawal 

rate for a once-through cooling water system is dependent on plant capacity (kW) 

and independent of plant electrical generation (kWh). For this reason, the water 

usage factors for once-through systems were determined by dividing the sum of 

the average withdrawal or consumption rate by the sum of the generator summer 

capacity. 

Withdrawal Factor (gal/kWh) = ΣAverage Withdrawal (gal/h) / ΣCapacity (kW) (1a) 

Consumption Factor (gal/kWh) = ΣAverage Consumption (gal/h) / ΣCapacity (kW) (1b) 

 

o Wet Recirculating Systems: Similar to once-through systems, to maximize plant 

efficiency during partial load operation, power plant operators normally maintain 

cooling water flow through the condenser and across the cooling tower at full load 

design rates. However, as more power is produced, the heat load to the cooling 

tower increases, resulting in greater evaporative losses and blowdown and 

consequently, higher water withdrawal requirements. Therefore, water 

withdrawal and consumption are independent of plant capacity (kW) and 

dependent on plant electrical generation (kWh) in wet recirculating systems. For 

this reason, the water usage factors for wet recirculating cooling systems were 

adjusted for each year of the analysis by applying a capacity factor ratio, F, to 

account for the growth in generation. 

Withdrawal Factor (gal/kWh) = F x ΣAverage Withdrawal (gal/h) / ΣCapacity (kW) (2a) 

Consumption Factor (gal/kWh) = F x ΣAverage Consumption (gal/h) / ΣCapacity (kW) (2b) 

Where: 

F = Ratio of capacity factor in year X to capacity factor in baseline year 2003 

o Cooling Ponds: EIA-767 considers cooling ponds to be a type of wet 

recirculating cooling system since heat loss occurs through evaporative loss. 

However, cooling water flow rates for a cooling pond are more similar to oncethrough than wet recirculating systems. Therefore, for this study, water usage 

factors were calculated using the same formula as for once-through systems.
Freshwater Needs for Thermoelectric Generation, September 2007 

B-6 

o Dry Recirculating Systems: For dry recirculating systems, the cooling water 

withdrawal and consumption factors are both assumed to be zero.

Non-Coal Plants

Nuclear, oil steam, gas steam, and natural gas combined-cycle plants were classified 

according to NERC region, cooling water source (fresh or saline), and cooling water 

system (recirculating or once-through). Water usage factors for each plant classification 

were determined using equations 1a, 1b, 2a, and 2b, depending on type of cooling water 

system. 

In calculating water withdrawal and consumption quantities for combined-cycle plants, 

an adjustment was made to account for the fact that the gas turbine portion of the plant 

does not require cooling water. The design capacity of the gas turbine portion of a 

combined-cycle facility is typically twice that of the steam turbine portion; in other 

words, two-thirds of a combined-cycle plant’s total output is derived from the gas 

turbine(s). Therefore, only about one-third of the plant output is used for steam 

generation, with its associated water requirements. For this analysis, water withdrawal 

and consumption factors were applied to only one-third of the combined-cycle capacity. 

Step 3: Quality Control and Model Validation 

Step 3 represents just one of several efforts designed to ensure quality control for the 

analysis. Because models, by definition, are simplified representations of reality, 

absolute model accuracy is impossible to guarantee in any situation. It is important, 

however, to have procedures in place to ensure that output from a given analysis is 

consistent with reality and reasonable expectations. Several steps were taken for the 

water needs analysis to achieve this objective. 

The water withdrawal and consumption factors that were used in the model were 

obtained through a rigorous evaluation of data collected by the Energy Information 

Administration, primarily forms EIA-767 and EIA-860. Data presented on these forms is 

assumed to accurately represent conditions at a particular power plant. A variety of 

reasons, however, could account for errors and discrepancies in the data: lack of 

understanding of the form’s directions, data entered in the wrong places, inaccurate data 

entry, improperly aggregated data, and others. 

The calculated water withdrawal and consumption factors for a given categorical 

breakdown (e.g., NERC region) should fall within a limited range based on generation 

type and cooling type. If the dataset in that categorical breakdown was too small, data 

outliers could have disproportionately impacted the results. While it is impossible to 

eliminate all such errors, the data was carefully vetted to ensure quality data points were 

used. Certain entries were modified or discarded based on accompanying information 

and engineering judgment. For example, if a power plant was designated as a oncethrough facility, but reported cooling water withdrawal and consumption quantities that 

clearly identify it as a recirculating facility, the plant was re-classified as a recirculating 

facility. 
Freshwater Needs for Thermoelectric Generation, September 2007 

B-7 

To ensure that the estimates generated by the water needs analysis model were 

reasonable, power generation data from 1995 was obtained and inserted into the model. 

The calculated water withdrawal and consumption values for thermoelectric generation 

were then compared with U.S. Geologic Service estimates for water withdrawal and 

consumption for 1995. 

Step 4: Develop Future Cases 

Table B-2 summarizes the cases evaluated in the original 2004 analysis and the 

2006/2007 analysis. The effects of emerging issues, particularly the impact of the Clean 

Water Act 316(b) regulations,f

 were incorporated into the selection of the 2006/2007 

cases. Comments are provided with each of the cases to assess their likelihood and 

justify the chosen cases. Five cases were included in the 2006/2007 Water Needs 

Analysis, one reflecting status quo conditions, two reflecting varying levels of regulations 

regarding cooling water source, one incorporating dry cooling, and one reflecting 

regulatory pressures to convert existing once-through capacity to recirculating capacity. 

To determine total water withdrawal and consumption requirements for thermoelectric 

generation in future years, new capacity additions and existing capacity retirements were 

factored into the analysis. As noted in the table, retirements were modeled based on 

current source withdrawals; in other words, freshwater and saline units were retired from 

service in proportion to their current contributions to total installed capacity, which is 

thought to more accurately reflect industry behavior. Units recently retired and/or placed 

in cold reserve have been removed from service due to age and operational cost 

constraints; cooling water source has played a minimal or nonexistent role. Future 

capacity retirement decisions, therefore, will likely remain more dependent on age and 

operational costs than cooling water source, and should reflect current proportions of 

freshwater and saline water facilities. 

Retired capacity in a given NERC region was broken down by generation type, water 

source, cooling type, and, where applicable, boiler and FGD type, based on the current 

proportion of capacity for each specific combination. The corresponding water 

withdrawal and consumption factors were then applied to the retired capacity to 

determine how much water must be deducted from the withdrawal and consumption 

totals. 

In modeling capacity additions, it was necessary to consider the different thermoelectric 

generation types. A variety of model plants were added based on the case assumptions. 

Expected capacity additions in a given region in a given year, as projected by AEO 

2006/2007, were apportioned into these model plant categories. Each model plant will 

 

f

 The Clean Water Act’s 316(b) regulations require the U.S. Environmental Protection Agency to ensure 

that cooling water intake structures at power plants and other manufacturing facilities reflect the best 

technology available for minimizing adverse environmental impact. The practical impact of these 

regulations is that most new power plants will have to incorporate closed-loop, recirculating cooling 

systems, which overwhelmingly rely on freshwater. 
Freshwater Needs for Thermoelectric Generation, September 2007 

B-8 

have an associated water withdrawal and consumption factor. The corresponding 

capacity (kW) for each model plant category was used with the withdrawal and 

consumption factors to calculate incremental water withdrawal and consumption. 

The model plants for the five cases are listed in Table B-3. Because of the resolution 

provided in this analysis for coal-fired power plants, more model plants were developed 

for coal than for the other generation types. Several notes are in order regarding the coal 

model plants: 

• For pulverized coal plants, new additions are expected to favor supercritical boiler 

technology. Nationwide, the current split between subcritical and supercritical 

boiler technology capacity is 73% subcritical/27% supercritical, reflecting greater 

industry experience and familiarity with subcritical technology. Pressure from 

several sources – environmental entities, state utility commissions, the threat of 

CO2 regulations – is increasing utility interest in supercritical boiler technology. 

A majority of the coal-fired power plants currently under construction or planned 

will rely on supercritical boiler technology. In selecting model coal plants for 

new additions, therefore, a 75% supercritical/25% subcritical split was employed. 

See Appendix B for further information. 

• For coal-fired power plants equipped with flue gas desulfurization equipment, 

water withdrawal and consumption rates can exhibit relatively significant 

differences based on whether the FGD is a wet or dry system. Since all new 

pulverized coal-fired power plants will need FGD systems to comply with 

emission regulations, future capacity additions must be apportioned by FGD type. 

Since emission regulations do not dictate technology selection, the analysis 

apportions FGD type to new capacity additions based on the existing split in the 

coal-fired power fleet (by summer capacity), which is 90% wet/10% dry. 

• The Annual Energy Outlook assumes that a portion of new coal-fired capacity will 

utilize integrated gasification combined-cycle (IGCC) technology. The water 

requirements for IGCC facilities differ from those at pulverized coal facilities. 

While both require cooling water, IGCC requires substantially less since a large 

fraction of the output from an IGCC plant is produced from the combustion 

turbines, which require minimal water. Moreover, since IGCC relies on water for 

significant process (non-cooling) use, it is unlikely that a saline water source 

would be desirable. The model IGCC coal plant, therefore, is restricted to 

freshwater use. 

As discussed above, model plants for the non-coal thermoelectric generation capacity – 

nuclear, oil steam, gas steam, and natural gas combined cycle – were broken down by 

water source (fresh or saline) and cooling water type (once-through or wet recirculating) 

based on data from the EIA-767 and EIA-860 databases. Two model plants account for 

all likely new non-coal thermoelectric additions: a plant using a freshwater recirculating 

system and a plant using a saline once-through system. For Case 4, an additional model 

plant with dry cooling is included for both coal and non-coal generation types. 
Freshwater Needs for Thermoelectric Generation, September 2007 

B-9 

Table B-2 - Case Selection, 2004 vs. 2006/2007 

2004 Water Needs Analysis 

Case description Comments 

Case 1: All additions and retirements 

occur at facilities using freshwater. 

Reasonable. While the vast majority of new additions will use 

freshwater due to 316(b) regulations, it is unlikely that the 

majority of retirements will be from freshwater facilities. 

Retirement decisions will depend more on age and operational 

costs than on cooling water source. 

Case 2: Additions and retirements are 

proportional to current source 

withdrawals (70% freshwater/30% 

saline). 

Reasonable. As discussed for Case 1, retirement decisions will 

depend on age and operational costs, which will likely mirror 

the proportional split between freshwater and saline. For 

additions, however, 316(b) regulations will likely lead to a 

higher proportion of freshwater facilities since saline water is 

incompatible with wet recirculation systems. 

Case 3: All additions and retirements 

occur at facilities using saline water. 

Unlikely. Due to 316(b) regulations, saline water will likely 

account for a significantly smaller percentage of new additions. 

Retirements may slightly favor saline, but decision will depend 

more on age and operational costs. 

Case 4: Additions occur at freshwater 

facilities, while retirements occur at 

saline facilities. 

Reasonable. Although retirements are likely to be more 

proportional to current source withdrawals, as discussed above. 

Case 5: Additions occur at saline 

facilities, while retirements occur at 

freshwater facilities. 

Extremely unlikely. 316(b) regulations will make saline a 

difficult choice for additions. No regulatory or operational 

trends indicate that retirements would favor freshwater. 

Case 6: All retired coal units use oncethrough cooling and are repowered 

using the existing once-through 

system. Additions reduced by the 

repowered units. 

Unlikely. Via repowering, units would be subject to new source 

regulations, which favor recirculating systems and the use of 

freshwater. 

 

2006/2007 Water Needs Analysis 

Case Description Rationale 

Case 1: Additions and retirements 

proportional to current water source 

and type of cooling system. 

Status quo scenario case. Assumes additions and retirements 

follow current trends. 

Case 2: All additions use freshwater 

and wet recirculating cooling, while 

retirements are proportional to current 

water source and cooling system. 

Regulatory-driven case. Assumes 316(b) and future regulations 

dictate the use of recirculating systems for all new capacity. 

Retirement decisions hinge on age and operational costs rather 

than water source and type of cooling system. 

Case 3: 90% of additions use 

freshwater and wet recirculating 

cooling, and 10% of additions use 

saline water and once-through cooling, 

while retirements are proportional to 

current water source and cooling 

system. 

Regulatory-light case. New additions favor the use of freshwater 

recirculating systems, but some saline capacity is permitted. 

Retirement decisions remain tied to age and operational costs, 

tracking current source withdrawals. 

Case 4: 25% of additions use dry 

cooling and 75% of additions use 

freshwater and wet recirculating 

cooling. Retirements are proportional 

to current water source and cooling 

system. 

Dry cooling case. Regulatory and public pressures result in 

significant market penetration of dry cooling technology. 

Retirement decisions remain tied to age and operational costs, 

tracking current source withdrawals. 

Case 5: Additions use freshwater and 

wet recirculating cooling, while 

Conversion case. Same as Case 2, except regulatory and public 

pressures compel state agencies to dictate the conversion of a 
Freshwater Needs for Thermoelectric Generation, September 2007 

B-10 

retirements are proportional to current 

water source and cooling system. 5% 

of existing freshwater once-through 

cooling capacity retrofitted with wet 

recirculating cooling every 5 years 

starting in 2010. 

significant amount of existing freshwater once-through cooling 

systems to wet recirculating. 

Table B-3 - Model Plants for New Capacity Additions

Case 1 

Coal • Pulverized coal, freshwater, recirculating cooling system 

o 75% supercritical/25% subcritical 

o Wet FGD/dry FGD based on existing split 

• Pulverized coal, saline water, once-through cooling system 

o 75% supercritical/25% subcritical 

o Wet FGD/dry FGD based on existing split 

• Integrated gasification combined-cycle, freshwater, recirculating 

Nuclear • Freshwater, recirculating cooling system 

• Saline water, once-through cooling system 

Non-coal fossil • Freshwater, recirculating cooling system 

• Saline water, once-through cooling system 

Case 2 

Coal • Pulverized coal, freshwater, recirculating cooling system 

o 75% supercritical/25% subcritical 

o Wet FGD/dry FGD based on existing split 

• Integrated gasification combined-cycle, freshwater, recirculating 

Nuclear • Freshwater, recirculating cooling system 

Non-coal fossil • Freshwater, recirculating cooling system 

Case 3 

Coal • Pulverized coal, freshwater, recirculating cooling system 

o 75% supercritical/25% subcritical 

o Wet FGD/dry FGD based on existing split 

• Pulverized coal, saline water, once-through cooling system 

o 75% supercritical/25% subcritical 

o Wet FGD/dry FGD based on existing split 

• Integrated gasification combined-cycle, freshwater, recirculating 

Nuclear • Freshwater, recirculating cooling system 

• Saline water, once-through cooling system 

Non-coal fossil • Freshwater, recirculating cooling system 

• Saline water, once-through cooling system 

Case 4 

Coal • Pulverized coal, freshwater, recirculating cooling system 

o 75% supercritical/25% subcritical 

o Wet FGD/dry FGD based on existing split 

• Pulverized coal, freshwater, dry cooling system 

o 75% supercritical/25% subcritical 

o Wet FGD/dry FGD based on existing split 

• Integrated gasification combined-cycle, freshwater, recirculating 

• Integrated gasification combined-cycle, dry cooling system 

Nuclear • Freshwater, recirculating cooling system 

• Dry cooling system 
Freshwater Needs for Thermoelectric Generation, September 2007 

B-11 

Non-coal fossil • Freshwater, recirculating cooling system 

• Dry cooling system 

Case 5 

Coal • Pulverized coal, freshwater, recirculating cooling system 

o 75% supercritical/25% subcritical 

o Wet FGD/dry FGD based on existing split 

• Integrated gasification combined-cycle, freshwater, recirculating 

Nuclear • Freshwater, recirculating cooling system 

Non-coal fossil • Freshwater, recirculating cooling system 

Step 5: Calculate regional withdrawal and consumption to 2030 

Step 5 integrates the water withdrawal and consumption factors calculated in Step 2 with 

the various cases defined in Step 4 to assess the regional and national impacts on water 

withdrawal and consumption out to 2030. 

The Annual Energy Outlook provides projections of future electricity generating capacity 

by year, by generation type and by NERC region. Apportioning this capacity among the 

chosen model plants for a given case and then applying the water withdrawal and 

consumption factors enables one to estimate water withdrawal and consumption trends. 

For a given case in a given region, the capacity additions and retirements projected by 

AEO 2006/2007 were first divided between freshwater and saline water based on the 

source withdrawal split for each technology type (coal, nuclear, non-coal fossil), as 

determined using existing fleet data. The additions and retirements were further 

apportioned among cooling water system type (once-through, recirculating), again using 

existing fleet splits. For nuclear and non-coal fossil, the water withdrawal and 

consumption factors determined in Step 2 were then applied to the resulting capacity 

amounts to calculate water withdrawal and consumption totals. 

For coal, further segregation was necessary before performing the calculations. The 

additions and retirements were further apportioned by technology type (supercritical and 

subcritical boilers). Retirements were divided based on the existing fleet split between 

supercritical and subcritical technology. Additions were divided between supercritical 

and subcritical boilers at a 75/25 ratio to reflect a growing preference for supercritical 

technology, as described above in Step 4 and in Appendix C. The additions also must 

accommodate new IGCC plants; AEO projections for IGCC were used to apportion 

capacity amounts by region. Finally, coal retirements and additions were apportioned by 

FGD type (wet, dry, none) using existing fleet data. The water withdrawal and 

consumption values determined in Step 2 were applied to the segregated capacity 

quantities determined in Step 5 to calculate water withdrawal and consumption totals. 

The calculations were a result of summing the results for each model plant in each region. 

The following is an example formula to calculate water withdrawal that was used for a 

model plant: 
Freshwater Needs for Thermoelectric Generation, September 2007 

B-12 

Water Withdrawal (gal/hr) = A x B x C (3) 

Where: 

A = Total regional capacity, kW 

B = Proportion of capacity assigned to model plant, %/100 

C = Capacity factor-weighted water use scaling factor for model plant, gal/kWh 

 
Freshwater Needs for Thermoelectric Generation, September 2007 

C-1 

Appendix C 

Future Coal-Fired Power Plant Boiler Type 

Supercritical versus Subcritical

The water analysis uses different water use scaling factors for coal-fired power plants 

based on boiler type. A supercritical boiler – operating at steam conditions above the 

critical point – is more efficient and therefore requires less cooling water flow than a 

subcritical boiler for an equivalent amount of electrical generation output. The critical 

point represents the highest temperature and pressure at which a substance can exist as a 

vapor and liquid in equilibrium. The critical point for water is 3200 psia and 705°F. 

Today’s supercritical boilers operate at steam conditions of approximately 3500 psia and 

1000°F compared to subcritical boilers that operate at approximately 2400 psia or less 

and 1000°F. 

Table C-1 presents a summary of the breakdown by boiler type for currently operating 

U.S. coal-fired power plants according to data taken from Platt’s UDI Power Plant 

Database. The current boiler type breakdown by MW capacity is 27% supercritical and 

73% subcritical. It should also be noted that supercritical boilers tend to be significantly 

larger in capacity. The average size of supercritical boilers is 743 MW compared to 234 

MW for subcritical boilers. 

Table C-1 – Boiler Type for Existing Plants 

Operating Plants Total 

Supercritical Subcritical 

No. Units 1,136 117 1,019 

Total Capacity, MW 325,651 86,903 238,748 

Average Unit Capacity, MW 287 743 234 

% Total Capacity Base 27% 73% 

Table C-2 presents a similar summary by boiler type for coal-fired power plants either 

under construction or planned also taken from Platt’s UDI Power Plant Database. 

However, not all of the plants reported boiler type. For those plants that boiler type is 

reported, the breakdown by capacity is 55% supercritical and 45% subcritical. Similar to 

the currently operating plants, the average size of supercritical plants is 719 MW 

compared to 312 MW for subcritical plants. Since it appears that plant capacity 

correlates fairly well with boiler type, the unreported plants are segregated into two plant 

sizes – greater than or equal to 500 MW (87%) and less than 500 MW (13%). 
Freshwater Needs for Thermoelectric Generation, September 2007 

C-2 

Table C-2 – Boiler Type for Future Plants – As Reported 

Plants Under Boiler Type Reported Boiler Type Not Reported 

Construction or 

Planned 

Total 

Total 

Supercritical Subcritical Total ≥ 500 

MW 

< 500 

MW 

No. Units 86 49 17 32 37 26 11 

Total Capacity, 

MW 42,835 22,203 12,225 9,978 20,632 17,887 2,745 

Average 

Capacity, MW 498 453 719 312 558 688 250 

% Total 

Capacity 55% 45% 87% 13% 

Based on the boiler type data in Table C-1 and reported boiler type data in Table C-2, it is 

apparent that plant capacity correlates fairly well with boiler type. As a result, the 

unreported plants in Table C-2 that were segregated by plant capacity can also be 

categorized by boiler type. Plants with a capacity greater than or equal to 500 MW are 

assumed to be supercritical and those with a capacity less than 500 MW are assumed to 

be subcritical. Table C-3 presents the result of this categorization by combining the 

reported and unreported plant data from Table C-2. Therefore, future coal-fired plant 

capacity is assumed to be split as 75% supercritical and 25% subcritical for the water 

analysis. 

Table C-3 – Boiler Type for Future Plants - Combined 

Plants Under Construction or 

Planned Total 

Supercritical Subcritical 

No. Units 86 43 43 

Total Capacity, MW 42,835 30,112 12,723 

Average Capacity, MW 498 700 296 

% Total Capacity 70% 30% 
Freshwater Needs for Thermoelectric Generation, September 2006 

D-1 

Appendix D 

Water Withdrawal and Consumption Factors 

Table D-1 – National Average Withdrawal and Consumption Factors for Model Coal Plants 

Model Plant Withdrawal 

Factor (gal/kWh) 

Consumption 

Factor (gal/kWh) 

Freshwater, Once-Through, Subcritical, Wet FGD 27.113 0.138 

Freshwater, Once-Through, Subcritical, Dry FGD 27.088 0.113 

Freshwater, Once-Through, Subcritical, No FGD 27.046 0.071 

Freshwater, Once-Through, Supercritical, Wet FGD 22.611 0.124 

Freshwater, Once-Through, Supercritical, Dry FGD 22.590 0.103 

Freshwater, Once-Through, Supercritical, No FGD 22.551 0.064 

Freshwater, Recirculating, Subcritical, Wet FGD 0.531 0.462 

Freshwater, Recirculating, Subcritical, Dry FGD 0.506 0.437 

Freshwater, Recirculating, Subcritical, No FGD 0.463 0.394 

Freshwater, Recirculating, Supercritical, Wet FGD 0.669 0.518 

Freshwater, Recirculating, Supercritical, Dry FGD 0.648 0.496 

Freshwater, Recirculating, Supercritical, No FGD 0.609 0.458 

Freshwater, Cooling Pond, Subcritical, Wet FGD 17.927 0.804 

Freshwater, Cooling Pond, Subcritical, Dry FGD 17.902 0.779 

Freshwater, Cooling Pond, Subcritical, No FGD 17.859 0.737 

Freshwater, Cooling Pond, Supercritical, Wet FGD 15.057 0.064 

Freshwater, Cooling Pond, Supercritical, Dry FGD 15.035 0.042 

Freshwater, Cooling Pond, Supercritical, No FGD 14.996 0.004 

Table D-2 – National Average Withdrawal and Consumption Factors for Model Nuclear Plants 

Model Plant Withdrawal Factor 

(gal/kWh) 

Consumption Factor 

(gal/kWh) 

Freshwater, Once-Through 31.497 0.137 

Freshwater, Recirculating 1.101 0.624 

Table D-3 – National Average Withdrawal and Consumption Factors for Model Fossil Non-Coal 

Plants 

Model Plant Withdrawal Factor 

(gal/kWh) 

Consumption Factor 

(gal/kWh) 

Freshwater, Once-Through 22.74 0.09 

Freshwater, Recirculating 0.25 0.16 

Freshwater, Cooling Pond 7.89 0.11 

Table D-4 – National Average Withdrawal and Consumption Factors for Model IGCC/NGCC Plants 

Model Plant Withdrawal 

Factor (gal/kWh) 

Consumption 

Factor (gal/kWh) 

NGCC, Freshwater, Once-Through 9.01 0.02 

NGCC, Freshwater, Recirculating 0.15 0.13 

NGCC, Freshwater, Cooling Pond 5.95 0.24 

NGCC Air Cooled 0.004 0.004 

IGCC, Freshwater, Recirculating 0.226 0.173 
Freshwater Needs for Thermoelectric Generation, September 2006 

E-1 

Appendix E 

Combined-Cycle Power Plants: 

Relative Contributions from Gas and Steam Turbines

Combined-cycle power plants integrate the power generating capabilities of gas turbines 

and steam turbines in a highly efficient manner. The waste heat generated by fuel 

combustion in the gas turbine is recovered in a heat recovery steam generator, producing 

steam that is then used to generate additional power in the steam turbine. A common rule 

of thumb for combined-cycle design is that the gas turbine capacity is about twice that of 

the steam turbine (i.e., steam turbine output represents about one-third of total plant 

output). 

The water needs analysis incorporates this rule of thumb by applying the water 

withdrawal and consumption factors to only one-third of the combined-cycle capacity. 

To justify this assumption, the Platts World Electric Power Plants Database was 

analyzed. For those plants reporting gas turbine and steam turbine capacity in a 

combined-cycle configuration, the database produced the numbers shown in the table 

below. 

Table E-1 - Gas and Steam Turbine Contribution 

 Capacity (MW) Percentage Number of units Percentage 

Gas turbines in 

combined-cycle 

configuration 

93,526 62.1% 846 63.2% 

Steam turbines in 

combined-cycle 

configuration 

57,068 37.9% 493 36.8% 

Total 150,594 100.0% 1339 100.0% 

Steam turbine capacity represents about 38% of total combined-cycle capacity. While the 

data do not precisely equal the 2:1 ratio posited by the rule of thumb, the agreement is 

fairly close. Industry product evolution and individual plant design data also support the 

2:1 ratio. Siemens Power Generation recently expanded its product portfolio with the 

SGT5-8000H gas turbine, featuring advanced H-class efficiency.27 This turbine will be 

capable of producing about 340 MW in simple-cycle configuration, and about 530 MW 

in combined-cycle configuration, resulting in a steam turbine percentage of 35.8%. In the 

forthcoming NETL report, “2006 Cost and Performance Comparison of Fossil Energy 

Power Plants,” the steam turbine in the natural gas-fired combined-cycle design 

represents 29.2% of total plant output.28

Based on this information, assuming that the water scaling factors should only be applied 

to one-third of the generating capacity for combined-cycle plants appears quite 

reasonable. 
Freshwater Needs for Thermoelectric Generation, September 2007 

F-1 

Appendix F 

Results from Statistical Analysis of Water Usage Factor Data 

Figure F-1 – Boxplot for All Water Usage Factor Data for 

Coal Recirculating Subcritical Category 

Recirculating Subcritical

120000.00

100000.00

80000.00

60000.00

40000.00

20000.00

0.00

gal/MWh

Figure F-2 - Boxplot for Water Usage Factor Data for Coal Recirculating 

Subcritical Category with Outliers Eliminated 

Recirculating Subcritical

800.00

600.00

400.00

200.00

0.00

gal/MWh
Freshwater Needs for Thermoelectric Generation, September 2007 

F-2 

Figure F-3 – Boxplot for All Water Usage Factor Data for 

Coal Recirculating Supercritical Category 

Recirculating Supercritical

100000.00

80000.00

60000.00

40000.00

20000.00

0.00

gal/MWh

Figure F-4 - Boxplot for Water Usage Factor Data for Coal Recirculating 

Supercritical Category with Outliers Eliminated 

Recirculating Supercritical

1200.00

1000.00

800.00

600.00

400.00

200.00

gal/MWh
Freshwater Needs for Thermoelectric Generation, September 2007 

F-3 

Figure F-5 – Boxplot for All Water Usage Factor Data for 

Coal Once-Through Subcritical Category 

Once-Through Subcritical

10000000.00

8000000.00

6000000.00

4000000.00

2000000.00

0.00

gal/MWh x Design Temperature Rise

Figure F-6 - Boxplot for Water Usage Factor Data for Coal Once-Through 

Subcritical Category with Outliers Eliminated 

Once-Through Subcritical

1000000.00

800000.00

600000.00

400000.00

200000.00

gal/MWh x Design Temperature Rise
Freshwater Needs for Thermoelectric Generation, September 2007 

F-4 

Figure F-7 – Boxplot for All Water Usage Factor Data for 

Coal Once-Through Supercritical Category 

Once-Through Supercritical

1000000.00

800000.00

600000.00

400000.00

200000.00

gal/MWh x Design Temperature Rise

Figure F-8 - Boxplot for Water Usage Factor Data for Coal Once-Through 

Supercritical Category with Outliers Eliminated 

Once-Through Supercritical

600000.00

550000.00

500000.00

450000.00

400000.00

350000.00

300000.00

250000.00

gal/MWh x Design Temperature Rise
Freshwater Needs for Thermoelectric Generation, September 2007 

F-5 

Figure F-9 – Boxplot for All Water Usage Factor Data for 

Coal Cooling Pond Subcritical Category 

Cooling Pond Subcritical

800000.00

600000.00

400000.00

200000.00

0.00

gal/MWh x Design Temperature Rise

Figure F-10 – Boxplot for All Water Usage Factor Data for 

Coal Cooling Pond Supercritical Category 

Cooling Pond Supercritical

1750000.00

1500000.00

1250000.00

1000000.00

750000.00

500000.00

gal/MWh x Design Temperature Rise
Freshwater Needs for Thermoelectric Generation, September 2007 

F-6 

Figure F-11 - Boxplot for Water Usage Factor Data for Coal Cooling Pond 

Supercritical Category with Outliers Eliminated 

Cooling Pond Supercritical

502000.00

500000.00

498000.00

496000.00

494000.00

492000.00

490000.00

gal/MWh x Design Temperature Rise

Figure F-12 – Boxplot for All Water Usage Factor Data for 

Fossil Non-Coal Recirculating Category 

Fossil Non-Coal Recirculating

400000.00

200000.00

0.00

gal/MWh
Freshwater Needs for Thermoelectric Generation, September 2007 

F-7 

Figure F-13 - Boxplot for Water Usage Factor Data for Fossil Non-Coal 

Recirculating Category with Outliers Eliminated 

Fossil Non-Coal Recirculating

1200.00

1000.00

800.00

600.00

400.00

200.00

0.00

gal/MWh

Figure F-14 – Boxplot for All Water Usage Factor Data for 

Fossil Non-Coal Once-Through Category 

Fossil Non-Coal Once-Through

10000000.00

8000000.00

6000000.00

4000000.00

2000000.00

0.00

gal/MWh x Design Temperature Rise
Freshwater Needs for Thermoelectric Generation, September 2007 

F-8 

Figure F-15 - Boxplot for Water Usage Factor Data for Fossil Non-Coal 

Once-Through Category with Outliers Eliminated 

Fossil Non-Coal Once-Through

1200000.00

1000000.00

800000.00

600000.00

400000.00

200000.00

0.00

gal/MWh x Design Temperature Rise

Figure F-16 – Boxplot for All Water Usage Factor Data for 

Fossil Non-Coal Cooling Pond Category 

Fossil Non-Coal Cooling Pond

400000.00

200000.00

0.00

gal/MWh x Design Temperature Rise
Freshwater Needs for Thermoelectric Generation, September 2007 

F-9 

Figure F-17 – Boxplot for All Water Usage Factor Data for 

Nuclear Recirculating Category 

Nuclear Recirculating

125000.00

100000.00

75000.00

50000.00

25000.00

0.00

gal/MWh

Figure F-18 - Boxplot for Water Usage Factor Data for Nuclear 

Recirculating Category with Outliers Eliminated 

Nuclear Recirculating

3000.00

2500.00

2000.00

1500.00

1000.00

500.00

0.00

gal/MWh
Freshwater Needs for Thermoelectric Generation, September 2007 

F-10 

Figure F-19 – Boxplot for All Water Usage Factor Data for 

Nuclear Once-Through Category 

Nuclear Once-Through

2500000.00

2000000.00

1500000.00

1000000.00

500000.00

0.00

gal/MWh x Design Temperature Rise

Figure F-20 - Boxplot for Water Usage Factor Data for Nuclear 

Once-Through Category with Outliers Eliminated 

Nuclear Once-Through

1000000.00

800000.00

600000.00

400000.00

200000.00

gal/MWh x Design Temperature Rise
Freshwater Needs for Thermoelectric Generation, August 2007 

G-1 

Appendix G 

Carbon Capture Technologies 

This appendix briefly describes the carbon capture technologies used for this analysis. 

Though other pre- and post-combustion carbon capture systems could be applied, such as 

other solvent based systems, sorbents, and membranes, the systems described below were 

selected because of the available data and that they are further developed compared to 

some of the emerging technologies. For all retrofit, new PC and new IGCC plants, a 

nominal 90% CO2 capture rate is used. The captured CO2 is dried and compressed to 

2,200 psig. 

PC Retrofits and New Builds with Carbon Capture 

All retrofitted and new PC plants are assumed to use monoethanolamine (MEA) solvent 

based absorption systems to remove the CO2 from the flue gas. This solvent based 

process is designed to recover high-purity CO2 from low-pressure streams that contain 

oxygen. The process uses a stripping tower to recover the CO2 from the solvent. 

The additional water required for both PC retrofits and new PC plant with the solvent 

based carbon capture technologies is largely due to the additional cooling water 

requirements used for these systems. Cooling water is indirectly used to lower the 

temperature of the flue gas down to approximately 100°F. The water in the flue gas is 

condensed out and internally used within the plant. The compression and dehydration of 

the CO2 is the other process that increases cooling water use. As the CO2 is compressed, 

heat is generated. Intercoolers are used between compression stages to cool the CO2

fluid. Additional cooling water within the CO2 capture system is also used for water wash 

cooling, absorber intercooling, reflux condenser, reclaimer cooling, and lean solvent 

cooler.15 

For the PC retrofits, it is assumed that the sulfur levels in the flue gas are acceptable for 

the carbon capture system. All additional cooling systems required for the retrofits will 

be recirculating. Makeup water for the amine system is drawn from the recycled water 

that is condensed from the flue gas. 

New IGCC Plants with Carbon Capture 

For this analysis, all IGCC plants with carbon capture technologies utilize a two-staged 

Selexol process. Untreated syngas enters the first of two absorbers where H2S is 

preferentially removed using loaded solvent form the CO2 absorber. The gas exiting the 

first absorber passes through the second absorber where the CO2 is removed. Additional 

water used for the capture technologies is due to the increased cooling load required to 

further cool the syngas before entering the Selexol process and steam for the water gas 

shift (WGS) reactor. The WGS reactors are located before the Selexol unit and convert 

the carbon monoxide (CO) to CO2. Water is required for this reaction: 
Freshwater Needs for Thermoelectric Generation, September 2007 

F-2 

CO + H2O ↔ CO2 + H2

Products from the gasifier are humidified with steam or water and contain a portion of the 

water vapor necessary to meet the water-to-gas criteria at the reactor inlet.
Freshwater Needs for Thermoelectric Generation, September 2007 

R-1 

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Vaysman, Jay S. White, U.S. Department of Energy, National Energy Technology Laboratory, August 

2005. 

http://www.netl.doe.gov/technologies/coalpower/gasification/pubs/pdf/WaterReport_IGCC_Final_August2

005.pdf

4

 United States Geological Survey (USGS). Estimated Use of Water in the United States in 2000; USGS 

Circular 1268; March 2004. 

5

 USGS. Estimated Use of Water in the United States in 1995; USGS Circular 1200; 1998. 

http://water.usgs.gov/watuse/pdf1995/pdf/circular1200.pdf

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 Energy Information Administration. Annual Energy Outlook 2007, EIA Report No. DOE/EIA0383(2006); February 2007. 

7

 GAO, Freshwater Supply: States’ View of How Federal Agencies Could Help Them Meet the Challenges 

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 National Oceanic and Atmospheric Administration, National Climatic Data Center 

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Circular 1261, 2005 

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Half Century, Topical Report No. 1006786, March 2002. 13 Integrated Environmental Control Model, Carnegie Mellon University, 2004. http://www.iecmonline.com/

14 U.S. Department of Energy, National Energy Technology Laboratory, Carbon Dioxide Capture from 

Existing Coal-Fired Power Plants, December 2006. 15 U.S. Department of Energy, National Energy Technology Laboratory, Cost and Performance 

Comparison Baseline for Fossil Energy Power Plants, May 2007. 16 Energy Information Administration, Annual Energy Outlook 2006 with Projections to 2030, EIA Report 

No. DOE/EIA-0383(2006), February 2006. 

17 Timothy B. Wheeler, The Baltimore Sun, Running Dry? Maryland’s Growth Could Threaten Water 

Supplies, and Towns Have Been Forced to Curtail Development, February 5, 2006 18 National Energy Technology Laboratory, Power Plant Water Usage and Loss Study, August 2005. 19 GAO, Freshwater Supply: States’ View of How Federal Agencies Could Help Them Meet the Challenges 

of Expected Shortages, July 2003 20 DOI, Federal Drought Action Team will Coordinate Drought Relief Assistance to Western States, July 

2005 

21 Shea Anderson, Reuters, Idaho Committee Adopts Moratorium on Coal Power, March 14, 2006. 22 Land Letter. Western Power Plants Come Under Scrutiny as Demand and Drought Besiege Supplies;

March 4, 2004; http://www.eenews.net/Landletter.htm 23 Billingsgazette.com. South Dakota Governor Seeks Summit on Missouri River, February 2005. 24 Milwaukee Journal Sentinel. Wisconsin Energy Just Can’t Stay Out of the News with Their Intake 

Structures, February 18, 2005. 25 Erny Zah, The Daily Times, Desert Rock Water Agreement Passes Navajo National Committee, February 

2, 2006 

26 The Associated Press, Sempra Energy Halts Gerlach Project Study, March 8, 2006 27 http://www.powergeneration.siemens.com/en/gasturbinesitem/ls/sgt5_8000h/index.cfm
Freshwater Needs for Thermoelectric Generation, September 2007 

R-2 

 28 U.S. Department of Energy, National Energy Technology Laboratory, 2006 Cost and Performance 

Comparison of Fossil Energy Power Plants, June 2006