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United States General Accounting Office: 
GAO: 

Report to Congressional Committees: 

June 2002: 

Air Pollution: 

Emissions from Older Electricity Generating Units: 

GAO-02-709: 

Contents: 

Letter: 

Results in Brief: 

Background: 

Units that Began Operation before 1972 Emitted More Sulfur Dioxide and 
Nitrogen Oxides per Unit of Electricity Produced than Newer Units: 

Emissions from Older Units Were Often Higher than the Emissions 
Standards for Newer Units: 

Agency Comments: 

Scope and Methodology: 

Appendix I: Electricity Generation and Emissions from Older Units: 

Appendix II: GAO Contacts and Staff Acknowledgments: 

Table: 

Table 1: Electricity Generation and Emissions of Sulfur Dioxide, 
Nitrogen Oxides, and Carbon Dioxide from Older Units by State, 2000: 

Figures: 

Figure 1: Percentage of Total U.S. Emissions Released by Fossil-Fuel 
Generating Units, the Transportation Sector, and Other Sources in 1999: 

Figure 2: Emissions per Megawatt-Hour of Electricity Generated, 2000: 

Figure 3: Sulfur Dioxide Emissions from Older Units, 2000: 

Figure 4: Nitrogen Oxides Emissions from Older Units, 2000: 

Figure 5: Carbon Dioxide Emissions from Older Units, 2000: 

Figure 6: Proportion of Older Units’ Emissions that Were Higher than 
New Source Standards in 2000: 

Figure 7: Additional Sulfur Dioxide Emissions from Older Units, 2000: 

Figure 8: Additional Nitrogen Oxides Emissions from Older Units, 2000: 

[End of section] 

United States General Accounting Office: 
Washington, DC 20548: 

June 12, 2002: 

The Honorable James M. Jeffords: 
Chairman, Committee on Environment and Public Works: 
United States Senate: 

The Honorable Joseph I. Lieberman: 
Chairman, Subcommittee on Clean Air, Wetlands, and Climate Change: 
Committee on Environment and Public Works: 
United States Senate: 

Electricity is critical to the nation’s economy and standard of living. 
The nation depends on a variety of fuels to generate this electricity, 
including coal, natural gas, nuclear power, oil, and renewable sources. 
While fossil fuels—coal, natural gas, and oil—account for more than two 
thirds of our electricity, generating units that burn these fuels are 
major sources of airborne emissions that pose human health and 
environmental risks. Two of the substances emitted, sulfur dioxide and 
nitrogen oxides, have been linked to respiratory illness and acid rain. 
A third, carbon dioxide, has been linked to global climate change and 
its potential adverse effects, including drought and severe weather 
conditions. Addressing these concerns without compromising economic and 
energy goals continues to pose significant challenges. 

To help limit emissions and protect air quality, the Environmental
Protection Agency (EPA), under the Clean Air Act, regulates emissions of
sulfur dioxide and nitrogen oxides from a variety of sources including
electricity generating units that burn fossil fuels, other industrial 
sources, and automobiles. EPA does not regulate carbon dioxide. Under 
the Clean Air Act, EPA requires certain electricity generating units 
built or modified after August 17, 1971, to meet uniform national 
emissions standards for the regulated substances.[Footnote 1] Units 
built before that date that have not undergone modifications do not 
have to meet these standards. In passing the act, the Congress directed 
EPA to establish standards for units built or modified after that date, 
on the basis of evidence that adding pollution controls at the time of 
construction was more efficient than adding them to all existing units. 

Many of the older units still operate—1,396 (57 percent) of the fossil-
fuel units that generated electricity in 2000 began operating before 
1972.[Footnote 2] (We refer to fossil-fuel generating units that began 
operation before 1972 as “older units” and those that began operating 
in 1972 or later as “newer units.”) Provided they otherwise comply with 
the act, these older units may legally emit sulfur dioxide and nitrogen 
oxides at higher rates than newer units that are subject to new source 
standards. Thus, one way of describing the air quality impact of the 
older units is to estimate their “additional” emissions—that is, the 
difference between their actual emissions during a given period and the 
maximum emissions allowed under the new source standards. 

In May 2001, the administration issued a National Energy Policy report,
which cited forecast needs by the Energy Information Administration for
additional power plants over the next 20 years. In your September 2001
letter, you asked us to provide information on, among other things, air
emissions from future electricity generation. As part of this work, 
which we will present in a subsequent report, we obtained information 
and briefed your offices on emissions in 2000 (the most current data 
available) from existing units that burned fossil fuel. This report 
transmits that information. Specifically, we determined: 

* the proportions of sulfur dioxide, nitrogen oxides, and carbon dioxide
emitted and electricity generated by older fossil-fuel units (as a 
group) relative to newer units (as a group) in 2000, as well as the 
locations and type of fuel burned by units responsible for the majority 
of the emissions; and; 

* the proportions of older fossil-fuel units that, in 2000, emitted 
sulfur dioxide and nitrogen oxides at rates above the new source 
standards applicable to newer units, the location of these additional 
emissions, and the type of fuel burned by these units. 

To address these objectives we analyzed data on air emissions and
electricity generation from units with a generating capacity greater 
than 15 megawatts.[Footnote 3] We obtained these data from Platts/RDI, 
a private vendor that integrates data on air emissions from EPA with 
data on electricity generation and the age of individual units from the 
Energy Information Administration. While these data were the most 
comprehensive available, they may understate the total emissions from 
fossil-fuel units because some units are not required to report their 
emissions to regulatory agencies. The units that did not report 
emissions, however, generated less than 1 percent of the electricity 
from older units in 2000. Of the 1,396 operating older units, 1,157 (83 
percent) reported emissions data in 2000. 

Results in Brief: 

Older electricity generating units—those that began operating before
1972—emitted 59 percent of the sulfur dioxide, 47 percent of the 
nitrogen oxides, and 42 percent of the carbon dioxide from fossil-fuel 
units in 2000, while generating 42 percent of all electricity produced 
by fossil-fuel units. Units that began operating in or after 1972 were 
responsible for the remainder of the emissions and electricity 
production. For equal quantities of electricity generated, older units, 
in the aggregate, emitted about twice as much sulfur dioxide and about 
25 percent more nitrogen oxides than did the newer units which must 
meet the new source standards for these substances. Older and newer 
units emitted about the same amount of carbon dioxide for equal 
quantities of electricity generated. Of the older units, those in the 
Mid-Atlantic, Midwest, and Southeast produced the majority of the 
emissions, and in disproportionate quantities for the amount of 
electricity they generated compared with units located in other parts 
of the country. Older units that burned coal released a 
disproportionate share of emissions for the electricity they produced
compared with units burning natural gas and oil. 

In 2000, 36 percent of older units emitted sulfur dioxide at levels 
above the new source standards applicable to newer units, and 73 
percent emitted nitrogen oxides at levels above the standards. These 
“additional” emissions—those above the standards for newer 
units—accounted for 34 percent of the sulfur dioxide and 60 percent of 
the nitrogen oxides produced by older units. Most of the additional 
emissions were released from units located in the Mid-Atlantic, 
Midwestern, and Southeastern United States. Coal-burning units emitted 
99 percent of the additional sulfur dioxide and 91 percent of the 
additional nitrogen oxides, while other fossil fuel-burning units 
accounted for the remainder. 

Background: 

Sulfur dioxide and nitrogen oxides have been linked to a variety of 
health and environmental concerns, and carbon dioxide has been linked 
to global warming. For example, sulfur dioxide and nitrogen oxides 
contribute to the formation of fine particles,[Footnote 4] and nitrogen 
oxides contribute to the formation of ozone.[Footnote 5] Both fine 
particles and ozone have been linked to respiratory illnesses. For 
example, fine particles have been linked to premature death, aggravated 
asthma, and chronic bronchitis, while ozone can inflame lung tissue and 
increase susceptibility to bronchitis and pneumonia. In addition to 
affecting health, sulfur dioxide and nitrogen oxides reduce visibility 
and contribute to acid rain, which harms aquatic life and degrades 
forests. Carbon dioxide has been linked to increases in air and ocean 
temperatures. Such climate changes, by the end of the century, could 
cause rising sea levels, droughts, and wind and flood damage, according 
to the National Academy of Sciences. 

Electricity generating units that burn fossil fuels, along with other
stationary sources (such as chemical manufacturers and petroleum
refineries), and transportation sources (such as cars) emit one or all 
of these substances. Figure 1 compares emissions of sulfur dioxide, 
nitrogen oxides, and carbon dioxide from fossil-fuel units to those 
from other sources in 1999, the most recent year for which data for all 
three substances were available. While the overall proportion of each 
substance emitted by fossil-fuel units varied—from 67 percent of all 
sulfur dioxide to 23 percent of all nitrogen oxides—these units emitted 
more of each substance than any other industrial source in 1999. 

Figure 1: Percentage of Total U.S. Emissions Released by Fossil-Fuel 
Generating Units, the Transportation Sector, and Other Sources in 1999: 

[Refer to PDF for image] 

This figure is a stacked horizontal bar graph depicting the following 
data: 

Percentage of Total U.S. Emissions Released by Fossil-Fuel Generating 
Units, the Transportation Sector, and Other Sources in 1999: 

Emission: Sulfur Dioxide: 
Fossil-fuel Electricity Generating Units: 67%; 
Transportation: 2%; 
All Other Sources: 31%. 

Emission: Nitrogen Oxides; 
Fossil-fuel Electricity Generating Units: 23%; 
Transportation: 34%; 
All Other Sources: 44%. 

Emission: Carbon Dioxide; 
Fossil-fuel Electricity Generating Units: 35%; 
Transportation: 31%; 
All Other Sources: 34%. 

Note: Transportation data for nitrogen oxides and sulfur dioxide 
include only highway vehicles. Data for carbon dioxide include other 
transportation sources, such as aircraft and boats. Percentages for
nitrogen oxides do not total 100 due to rounding. 

Source: EPA. 

[End of figure] 

Under the Clean Air Act, EPA establishes air quality standards and 
regulates emissions from a number of sources, including electricity
generating units that burn fossil fuels. The act required EPA to issue
regulations establishing federal performance standards for new sources 
of air pollution within certain categories of stationary sources. 
Accordingly, EPA issued new source standards for certain generating 
units with a capacity greater than 73 megawatts that were built or 
modified after August 17, 1971. Over time, EPA has made the standards 
more stringent, subjecting other types of units and those with a lower 
generating capacity to the standards. The standards do not apply to 
older units built before that date that have not been modified, 
although some older units do meet the standards. In addition, under a 
program called New Source Review, older units must install modern 
pollution controls when they make “major modifications” that 
significantly increase their emissions. The level of control required 
depends on the air quality in the area where the unit is located—a unit 
in an area that does not meet federal air quality standards must 
install more stringent controls.[Footnote 6] 

Although older units are generally excluded from the new source 
standards, they are subject to the acid rain provisions of the Clean 
Air Act Amendments of 1990. The 1990 amendments directed EPA to reduce
emissions of sulfur dioxide from electricity generating units by 
setting a limit, known as a “cap,” on emissions from all units and 
establishing an emissions trading program. Under the trading program, 
each unit received emissions “allowances” that represent the right to 
emit one ton of sulfur dioxide. The allowances may be bought, sold, or 
banked for use in later years, but generating unit owners or operators 
must own enough allowances at the end of each year to cover their 
annual emissions. Although the program did not start until 1995, some 
units affected by the program complied earlier, according to EPA, 
thereby reducing sulfur dioxide emissions by about 2.2 million tons 
between 1990 and the end of 1994. Between 1995 and the end of 2000, the 
affected units reduced their sulfur dioxide emissions by 2.5 million 
tons (from 13.7 million tons in 1994 to 11.2 million tons in 2000)—a 
decline of about 18 percent. EPA expects the program to result in 
further reductions in sulfur dioxide emissions between 2000 and 2010. 

To reduce emissions of nitrogen oxides, the acid rain provisions of the
1990 amendments limited the annual rate of emissions for individual 
units, rather than imposing an annual aggregate tonnage of emissions. 
[Footnote 7] To achieve emissions reductions while minimizing the 
burden on generators, the legislation allowed companies with multiple 
units to comply with the prescribed rate by averaging their emissions 
rates across two or more units and ensuring that the average did not 
exceed the prescribed rate. Thus, individual older units may continue 
to emit at levels above the prescribed annual emissions rate. Although 
the program started in 1996, some of the affected units complied 
earlier, according to EPA, thereby reducing emissions of nitrogen 
oxides by 700,000 tons between 1990 and the end of 1995. Between 1996 
and the end of 2000, the affected units reduced their emissions of 
nitrogen oxides by 900,000 tons (from 6.0 million tons in 1995 to 5.1 
million tons in 2000)—a decline of 15 percent. 

Units that Began Operation before 1972 Emitted More Sulfur Dioxide and 
Nitrogen Oxides per Unit of Electricity Produced than Newer Units: 

In 2000, older units emitted more sulfur dioxide and nitrogen oxides—and
about the same amount of carbon dioxide—per unit of electricity 
produced than newer units. For each megawatt-hour of electricity 
generated, older units, in the aggregate, emitted about twice as much
sulfur dioxide as newer units—12.7 pounds at older units, compared with
6.4 pounds at newer units. Older units also emitted about 25 percent 
more nitrogen oxides than newer units—4.7 pounds versus 3.8 pounds—for
every megawatt-hour of electricity generated. Older and newer units both
emitted about 1 ton of carbon dioxide for each megawatt-hour of
electricity generated. (See figure 2.) Overall, while generating 42 
percent of the electricity, older units emitted 59 percent of the 
sulfur dioxide, 47 percent of the nitrogen oxides, and 42 percent of 
the carbon dioxide from fossil-fuel units.[Footnote 8] Units that began 
operating in 1972 or after were responsible for the remainder of the 
emissions and electricity production. 

Figure 2: Emissions per Megawatt-Hour of Electricity Generated, 2000: 

[Refer to PDF for image] 

This figure is a multiple vertical bar graph depicting the following 
data: 

Emissions per Megawatt-Hour of Electricity Generated, 2000: 

Sulfur dioxide and nitrogen oxides are reported in pounds; carbon 
dioxide is reported in tons. 

Emission: Sulfur Dioxide; 
Older Units: 12.7 pounds; 
Newer Units: 6.4 pounds; 

Emission: Nitrogen Oxides; 
Older Units: 4.7 pounds; 
Newer Units: 3.8 pounds. 

Emission: Carbon Dioxide; 
Older Units: 1.0 tons; 
Newer Units: 1.0 tons. 

Source: GAO analysis of Platts/RDI data. 

[End of figure] 

Of the older units, those in the Mid-Atlantic, Midwest, and Southeast
released most of the emissions, and in disproportionate quantities for 
the amount of electricity they produced.[Footnote 9] Specifically, 
older units in these regions accounted for 87 percent of the sulfur 
dioxide, 75 percent of the nitrogen oxides, and 70 percent of the 
carbon dioxide emitted from older units nationwide in 2000, while 
generating 67 percent of the electricity from all older units. 
(Appendix I presents, by state, data on older units’ electricity 
generation, emissions per megawatt-hour of electricity generated, and 
aggregate emissions.) 

Figures 3, 4, and 5 show the location of older units and the amount of
sulfur dioxide, nitrogen oxides, and carbon dioxide they emitted in 
2000. 

Figure 3: Sulfur Dioxide Emissions from Older Units, 2000: 

[Refer to PDF for image] 

This figure contains a map of the continental United States depicting 
the location of older units and the amount of sulfur dioxide they 
emitted in 2000, in the following categories: 

Emissions in thousand tons: 
192.76 to 240.96: 1 location; 
144.57 to 192.75: 2 locations; 
96.38 to 144.56: 6 locations; 
48.19 to 96.37: 26 locations; 
1 to 48.18: 275 locations; 
No emissions reported: 171 locations. 

Source: GAO analysis of Platts/RDI data. 

Note: Emissions data for units at the same location were aggregated. 
Emissions categories were determined by taking the level of emissions 
at the highest-emitting unit (or co-located units) and dividing into 
five equal categories. Because we aggregated emissions at co-located 
units, the numbers in parentheses represent the number of locations, 
rather than the number of individual generating units, in each 
category. 

[End of figure] 

Figure 4: Nitrogen Oxides Emissions from Older Units, 2000: 

[Refer to PDF for image] 

This figure contains a map of the continental United States depicting 
the location of older units and the amount of Nitrogen Oxides they 
emitted in 2000, in the following categories: 

Emissions in thousand tons: 
41.08 to 51.36: 1 location; 
30.81 to 41.07: 2 locations; 
20.54 to 30.80: 6 locations; 
10.27 to 20.53: 33 locations; 
1 to 10.26: 325 locations; 
None: 113 locations. 

Source: GAO analysis of Platts/RDI data. 

Note: Emissions data for units at the same location were aggregated. 
Emissions categories were determined by taking the level of emissions 
at the highest-emitting unit (or co-located units) and dividing into 
five equal categories. Because we aggregated emissions at co-located 
units, the numbers in parentheses represent the number of locations, 
rather than the number of individual generating units, in each 
category. 

[End of figure] 

Figure 5: Carbon Dioxide Emissions from Older Units, 2000: 

[Refer to PDF for image] 

This figure contains a map of the continental United States depicting 
the location of older units and the amount of carbon dioxide they 
emitted in 2000, in the following categories: 

Emissions in thousand tons: 
13,598.20 to 16,997.46: 3 locations; 
10,186.47 to 13,598.20: 9 locations; 
6,790.98 to 10,186.46: 25 locations; 
3,354.90 to 6,790.97: 58 locations; 
1 to 3,354.89: 379 locations; 
No emissions reported: 6 locations. 

Source: GAO analysis of Platts/RDI data. 

Note: Emissions data for units at the same location were aggregated. 
Emissions categories were determined by taking the level of emissions 
at the highest-emitting unit (or co-located units) and dividing into 
five equal categories. Because we aggregated emissions at co-located 
units, the numbers in parentheses represent the number of locations, 
rather than the number of individual generating units, in each 
category. 

[End of figure] 

Older units that burned coal released a disproportionate share of
emissions for the electricity they produced, compared with units burning
natural gas and oil. Coal-burning units emitted 99 percent of the sulfur
dioxide, 88 percent of the nitrogen oxides, and 85 percent of the carbon
dioxide from older units nationwide, while generating 79 percent of the
total electricity from older units. 

Emissions from Older Units Were Often Higher than the Emissions 
Standards for Newer Units: 

Older units generally do not have to meet the standards applicable to
newer units, and in 2000, many of the older units emitted sulfur dioxide
and nitrogen oxides at levels higher than what is permitted under the
standards applicable to newer units for one or both of the pollutants. 
In that year, 36 percent of older units emitted sulfur dioxide at 
levels above the new source standard for that pollutant, and 73 percent 
emitted nitrogen oxides at levels above the new source standard. 
Approximately 31 percent of all older units emitted both pollutants at 
levels above the new source standards.[Footnote 10] 

As shown in figure 6, in 2000, 34 percent of the total sulfur dioxide
emissions (2.13 million of 6.34 million tons) and 60 percent of the 
total nitrogen oxide emissions (1.41 million of 2.35 million tons) from 
older units were “additional” emissions—that is, emissions at levels 
above the standards applicable to newer units. The additional sulfur 
dioxide emissions represented 20 percent of the sulfur dioxide 
emissions from fossil-fuel units (older and newer), and the additional 
emissions of nitrogen oxides represented 28 percent of the emissions of 
nitrogen oxides from fossil-fuel units. 

Figure 6: Proportion of Older Units’ Emissions that Were Higher than 
New Source Standards in 2000: 

[Refer to PDF for image] 

This figure is a stacked vertical bar graph depicting the following 
data: 

Proportion of Older Units’ Emissions that Were Higher than New Source 
Standards in 2000: 

Emission: Sulfur Dioxide; 
Emissions below standards: 66%; 
Emissions above standards: 34%. 

Emission: Nitrogen Dioxides; 
Emissions below standards: 40%; 
Emissions above standards: 60%. 

Source: GAO Analysis of Platts/RDI data. 

[End of figure] 

Most of the additional emissions—91 percent of the sulfur dioxide and
78 percent of the nitrogen oxides—came from units located in the
Mid-Atlantic, Midwest, and Southeast. Figures 7 and 8 show the level of
additional emissions at older units in 2000. The majority of these
emissions—99 percent of the sulfur dioxide and 91 percent of the 
nitrogen oxides—were from coal units, while other fossil fuel-burning 
units accounted for the remainder. 

Figure 7: Additional Sulfur Dioxide Emissions from Older Units, 2000: 

[Refer to PDF for image] 

This figure contains a map of the continental United States depicting 
the location of older units and the amount of additional sulfur dioxide 
they emitted in 2000, in the following categories: 

Emissions in thousand tons: 
123.24 to 154.04: 1 location; 
92.43 to 123.23: 1 location; 
61.62 to 92.42: 3 locations; 
30.81 to 61.61: 14 locations; 
1 to 30.80: 155 locations; 
None: 307 locations. 

Source: GAO analysis of Platts/RDI data. 

Note: Emissions data for units at the same location were aggregated. 
Emissions categories were determined by taking the level of emissions 
at the highest-emitting unit (or co-located units) and dividing into 
five equal categories. Because we aggregated emissions at co-located 
units, the numbers in parentheses represent the number of locations, 
rather than the number of individual generating units, in each 
category. 

[End of figure] 

Figure 8: Additional Nitrogen Oxides Emissions from Older Units, 2000: 

[Refer to PDF for image] 

This figure contains a map of the continental United States depicting 
the location of older units and the amount of additional nitrogen 
oxides they emitted in 2000, in the following categories: 

Emissions in thousand tons: 
49.70 to 62.12: 1 location; 
37.28 to 49.69: 2 locations; 
24.85 to 37.27: 11 locations; 
12.43 to 24.84: 42 locations; 
1 to 12.42: 418 locations; 
No emissions reported: 6 locations. 

Source: GAO analysis of Platts/RDI data. 

Note: Emissions data for units at the same location were aggregated. 
Emissions categories were determined by taking the level of emissions 
at the highest-emitting unit (or co-located units) and dividing into 
five equal categories. Because we aggregated emissions at co-located 
units, the numbers in parentheses represent the number of locations, 
rather than the number of individual generating units, in each 
category. 

[End of figure] 

As noted, the additional emissions shown in figure 6 represent the
emissions by older units above the limits applicable to new sources. If 
the same older units had generated the same quantity of electricity in 
2000 but had met the new source standards, total emissions would have 
been lowered by an amount equal to the computed additional emissions.
However, a requirement that older units meet the standards could have
reduced the quantity of electricity generated, raised the price of 
electricity, and/or shifted generation among units. Among other things, 
owners might have chosen to retire some older units rather than incur 
the costs of meeting the standards. According to a December 2000 Energy 
Information Administration study, requiring older coal units to install 
pollution control equipment would, by 2010, result in retirements that 
would reduce the nation’s coal-based electricity generating capacity by 
7 percent more than is otherwise projected (and the total U.S. capacity 
from all fuels by 3 percent), based on 1999 capacity levels. The study 
projected that such a requirement would cause operators of coal units 
to spend $73 billion dollars to install pollution control equipment by 
2020. The study also concluded that electricity prices in 2010 would be 
4 percent higher with a requirement to install control equipment than 
they would be without one.[Footnote 11] 

If older units had been required to meet new source standards in 2000, 
to the extent practicable, other units might have increased their 
operations—for example, by running more hours each day—to meet the 
demand for electricity that would have otherwise been produced by the 
units that retired. Because it is not possible to determine exactly 
which units would have been retired or run more to meet the demand, it 
is not possible to quantify precisely what the emissions in 2000 would 
have been if all units had been required to meet the new source 
standards. In addition, generating units that increased production to 
meet the demand created by retirements could have purchased sulfur 
dioxide emissions allowances from the retired units. Thus, the net 
decrease in sulfur dioxide emissions would not have been as great as 
the level of additional emissions reported above. Similarly, it is 
difficult to predict precisely how such requirements would affect 
future emissions levels. Any new coal, natural gas, or oil units built 
to replace retired units would, at a minimum, have to meet the new
source standards, which would reduce the emissions for each quantity of
electricity generated. 

To meet the new source standards, older units would need to switch 
fuels, or add or upgrade pollution control equipment. Some older units 
already use pollution control equipment or have taken other actions to 
reduce their emissions of sulfur dioxide or nitrogen oxides. For 
example, we found that 681 older units met the sulfur dioxide standard 
by burning coal with low sulfur content. We also found that the use of 
emissions controls did not necessarily indicate that the units met the 
new source standards. 

For example, 399 older units with equipment to control their nitrogen
oxide emissions still exceeded the emissions standard applicable to 
newer units. 

Agency Comments: 

We provided EPA with a draft of this report for review and comment. We
subsequently received comments from the Office of Air Quality Planning
and Standards, and the Office of Atmospheric Programs. EPA generally
agreed with the information presented. Both offices suggested technical
changes to the report, which we have incorporated as appropriate. 

Scope and Methodology: 

To respond to the first objective, we reviewed information from the
Energy Information Administration and EPA on air emissions, electricity
generation, and the age of electricity generating units. While both 
agencies maintain such information, the data we needed for this 
analysis were not readily available in a user-friendly format. For 
example, EPA has reliable and timely emissions data, but the 2000 data 
were not available with information on electricity generation and the 
age of each unit. 

Because of these limitations, we obtained alternative data from 
Platts/RDI, a private vendor that integrates EPA’s emissions data with 
the Energy Information Administration’s data on electricity generation 
and the age of generating units. Specifically, we obtained and analyzed 
air emissions and electricity generation data for each active fossil-
fuel unit above 15 megawatts in generating capacity that started 
operating before 1972. For newer units, we obtained data on aggregate 
national emissions and electricity generation at units with a capacity 
above 15 megawatts. We chose 15 megawatts as the threshold capacity 
because units above that capacity accounted for almost all (about 99 
percent) of the electricity generation from all fossil-fuel units in 
2000. Because data on air emissions and the use of control equipment 
were available for only 1,157 of the 1,396 active units (83 percent), 
the data may not fully represent the total level of emissions and the 
number of units using control equipment. However, the units that did 
not report emissions data generated less than 1 percent of the 
electricity from older units and therefore are not likely to have
produced large quantities of emissions. 

To respond to the second objective, we identified the applicable new
source standard for each type of unit, as listed in the Code of Federal
Regulations, Title 40, part 60. We then determined the difference 
between the actual rate of emissions at each unit, in pounds of 
pollutant per unit of fuel consumed, and the rate allowed under the 
standard that applies to newer units with the same capacity that burn 
the same fuel. We then multiplied the difference by the amount of fuel 
burned in 2000 to determine the annual level of “additional” emissions. 
In cases where EPA has not issued a standard for a particular type of 
unit, we excluded such units from our analysis of additional emissions. 
Regulations for some types of generating units were promulgated after 
1971, but for purposes of this report we have not distinguished these 
units and have classified them as newer or older units based on their 
age. For example, EPA promulgated a regulation in 1978 requiring 
certain electric utility steam-generating units to meet new source 
standards. However, if one of these units was constructed after August 
17, 1971, but before September 18, 1978, we classified it as a newer 
unit even though it would not have to meet the new source standard. 

We did not attempt to estimate the costs or benefits of requiring older
units to meet the new source standards. Therefore our analysis does not
allow us to comment on the economic or energy security implications of
requiring older units to meet the standards. 

We conducted our work between October 2001 and May 2002 in accordance 
with generally accepted government auditing standards. As agreed with 
your offices, unless you publicly announce the contents of this report 
earlier, we plan no further distribution until 30 days from the report 
date. At that time, we will send copies to the Chairman and Ranking
Minority Member of the House Committee on Energy and Commerce and its 
Subcommittee on Energy and Air Quality; the House Committee on 
Government Reform and its Subcommittee on Energy Policy, Natural 
Resources, and Regulatory Affairs; the Ranking Minority Member of the
Senate Committee on Environment and Public Works, and its Subcommittee 
on Clean Air, Wetlands, and Climate Change; other interested members of 
Congress; the Administrator, EPA; the Secretary of Energy; the Director 
of the Office of Management and Budget; and other interested parties. 
We will also make copies available to others upon request. In addition, 
the report will be available at no charge on GAO’s Web site at 
[hyperlink, http://www.gao.gov]. 

If you have any questions about this report, please contact me at (202) 
512-3841. Key contributors to this report are listed in appendix II. 

Signed by: 

David G. Wood: 
Director, Natural Resources and Environment: 

[End of section] 

Appendix I: Electricity Generation and Emissions from Older Units: 

Table 1 presents, by state, data on older units’ electricity generation;
emissions of sulfur dioxide, nitrogen oxides, and carbon dioxide; and
aggregate emissions of these substances. 

Table 1: Electricity Generation and Emissions of Sulfur Dioxide, 
Nitrogen Oxides, and Carbon Dioxide from Older Units by State, 2000: 

State: Alabama; 
Electricity Generation (Megawatt Hours): 43,841,064; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 15.9; 
Sulfur Dioxide Emissions (Tons): 348,189; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.4; 
Nitrogen Oxides Emissions (Tons): 117,612; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.1; 
Carbon Dioxide Emissions (Tons): 50,247,087. 

State: Arizona; 
Electricity Generation (Megawatt Hours): 6,254,947; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 1.6; 
Sulfur Dioxide Emissions (Tons): 4,965; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 4.5; 
Nitrogen Oxides Emissions (Tons): 14,026; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 0.8; 
Carbon Dioxide Emissions (Tons): 5,154,604. 

State: Arkansas; 
Electricity Generation (Megawatt Hours): 4,344,950; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 1.5; 
Sulfur Dioxide Emissions (Tons): 3,362; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 2.9; 
Nitrogen Oxides Emissions (Tons): 6,195; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 0.7; 
Carbon Dioxide Emissions (Tons): 3,041,883. 

State: California; 
Electricity Generation (Megawatt Hours): 49,643,659; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Sulfur Dioxide Emissions (Tons): 0; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 0.7; 
Nitrogen Oxides Emissions (Tons): 16,196; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 0.6; 
Carbon Dioxide Emissions (Tons): 30,594,610. 

State: Colorado; 
Electricity Generation (Megawatt Hours): 9,751,898; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 6.8; 
Sulfur Dioxide Emissions (Tons): 33,234; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 4.9; 
Nitrogen Oxides Emissions (Tons): 23,764; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.2; 
Carbon Dioxide Emissions (Tons): 11,486,658. 

State: Connecticut; 
Electricity Generation (Megawatt Hours): 7,569,614; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 6.3; 
Sulfur Dioxide Emissions (Tons): 23,830; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 2.6; 
Nitrogen Oxides Emissions (Tons): 9,767; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 0.9; 
Carbon Dioxide Emissions (Tons): 6,546,837. 

State: Delaware; 
Electricity Generation (Megawatt Hours): 2,915,799; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 18.9; 
Sulfur Dioxide Emissions (Tons): 27,601; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 4.0; 
Nitrogen Oxides Emissions (Tons): 5,795; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.2; 
Carbon Dioxide Emissions (Tons): 3,597,684. 

State: District of Columbia; 
Electricity Generation (Megawatt Hours): 62,392; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 11.7; 
Sulfur Dioxide Emissions (Tons): 364; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 3.3; 
Nitrogen Oxides Emissions (Tons): 103; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.2; 
Carbon Dioxide Emissions (Tons): 72,187. 

State: Florida; 
Electricity Generation (Megawatt Hours): 38,894,598; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 10.1; 
Sulfur Dioxide Emissions (Tons): 195,543; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.7; 
Nitrogen Oxides Emissions (Tons): 110,722; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.0; 
Carbon Dioxide Emissions (Tons): 37,961,898. 

State: Georgia; 
Electricity Generation (Megawatt Hours): 26,114,968; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 14.4; 
Sulfur Dioxide Emissions (Tons): 187,523; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 6.2; 
Nitrogen Oxides Emissions (Tons): 80,521; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.0; 
Carbon Dioxide Emissions (Tons): 26,968,799. 

State: Idaho; 
Electricity Generation (Megawatt Hours): 0; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Sulfur Dioxide Emissions (Tons): 0; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Nitrogen Oxides Emissions (Tons): 0; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): [Empty]; 
Carbon Dioxide Emissions (Tons): 0. 

State: Illinois; 
Electricity Generation (Megawatt Hours): 49,414,341; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 10.8; 
Sulfur Dioxide Emissions (Tons): 267,923; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.1; 
Nitrogen Oxides Emissions (Tons): 125,767; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.1; 
Carbon Dioxide Emissions (Tons): 56,372,741. 

State: Indiana; 
Electricity Generation (Megawatt Hours): 49,504,150; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 18.2; 
Sulfur Dioxide Emissions (Tons): 449,498; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 6.3; 
Nitrogen Oxides Emissions (Tons): 156,414; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.1; 
Carbon Dioxide Emissions (Tons): 54,171,703. 

State: Iowa; 
Electricity Generation (Megawatt Hours): 8,373,882; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 10.6; 
Sulfur Dioxide Emissions (Tons): 44,481; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.9; 
Nitrogen Oxides Emissions (Tons): 24,669; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.3; 
Carbon Dioxide Emissions (Tons): 10,787,523. 

State: Kansas; 
Electricity Generation (Megawatt Hours): 7,383,865; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 3.5; 
Sulfur Dioxide Emissions (Tons): 13,062; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.0; 
Nitrogen Oxides Emissions (Tons): 18,582; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.1; 
Carbon Dioxide Emissions (Tons): 8,309,570. 

State: Kentucky; 
Electricity Generation (Megawatt Hours): 43,900,772; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 17.4; 
Sulfur Dioxide Emissions (Tons): 382,785; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 6.2; 
Nitrogen Oxides Emissions (Tons): 135,662; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.1; 
Carbon Dioxide Emissions (Tons): 50,019,689. 

State: Louisiana; 
Electricity Generation (Megawatt Hours): 15,061,362; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Sulfur Dioxide Emissions (Tons): 0; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 3.3; 
Nitrogen Oxides Emissions (Tons): 24,915; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 0.7; 
Carbon Dioxide Emissions (Tons): 10,361,639. 

State: Maine; 
Electricity Generation (Megawatt Hours): 546,501; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 17.1; 
Sulfur Dioxide Emissions (Tons): 4,683; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 3.1; 
Nitrogen Oxides Emissions (Tons): 852; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 0.9; 
Carbon Dioxide Emissions (Tons): 483,827. 

State: Maryland; 
Electricity Generation (Megawatt Hours): 20,043,853; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 18.9; 
Sulfur Dioxide Emissions (Tons): 189,797; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.8; 
Nitrogen Oxides Emissions (Tons): 57,846; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.0; 
Carbon Dioxide Emissions (Tons): 20,759,129. 

State: Massachusetts; 
Electricity Generation (Megawatt Hours): 16,044,319; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 8.2; 
Sulfur Dioxide Emissions (Tons): 65,729; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 3.1; 
Nitrogen Oxides Emissions (Tons): 24,811; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.0; 
Carbon Dioxide Emissions (Tons): 15,625,832. 

State: Michigan; 
Electricity Generation (Megawatt Hours): 34,882,007; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 11.7; 
Sulfur Dioxide Emissions (Tons): 203,421; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 3.9; 
Nitrogen Oxides Emissions (Tons): 68,674; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.1; 
Carbon Dioxide Emissions (Tons): 38,980,846. 

State: Minnesota; 
Electricity Generation (Megawatt Hours): 10,500,702; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 10.3; 
Sulfur Dioxide Emissions (Tons): 53,832; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 7.2; 
Nitrogen Oxides Emissions (Tons): 37,903; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.2; 
Carbon Dioxide Emissions (Tons): 12,603,068. 

State: Mississippi; 
Electricity Generation (Megawatt Hours): 7,285,810; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 4.3; 
Sulfur Dioxide Emissions (Tons): 15,745; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 6.2; 
Nitrogen Oxides Emissions (Tons): 22,470; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.0; 
Carbon Dioxide Emissions (Tons): 7,347,536. 

State: Missouri; 
Electricity Generation (Megawatt Hours): 27,776,027; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 8.8; 
Sulfur Dioxide Emissions (Tons): 122,550; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 6.5; 
Nitrogen Oxides Emissions (Tons): 89,622; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.1; 
Carbon Dioxide Emissions (Tons): 31,785,320. 

State: Montana; 
Electricity Generation (Megawatt Hours): 1,523,880; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 5.8; 
Sulfur Dioxide Emissions (Tons): 4,397; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 3.3; 
Nitrogen Oxides Emissions (Tons): 2,543; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.2; 
Carbon Dioxide Emissions (Tons): 1,898,300. 

State: Nebraska; 
Electricity Generation (Megawatt Hours): 4,922,776; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 6.9; 
Sulfur Dioxide Emissions (Tons): 16,944; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.4; 
Nitrogen Oxides Emissions (Tons): 13,371; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.2; 
Carbon Dioxide Emissions (Tons): 5,887,622. 

State: New Hampshire; 
Electricity Generation (Megawatt Hours): 3,971,049; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 22.7; 
Sulfur Dioxide Emissions (Tons): 45,027; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 4.0; 
Nitrogen Oxides Emissions (Tons): 7,969; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.2; 
Carbon Dioxide Emissions (Tons): 4,639,472. 

State: Nevada; 
Electricity Generation (Megawatt Hours): 15,193,917; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 5.8; 
Sulfur Dioxide Emissions (Tons): 43,920; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 4.2; 
Nitrogen Oxides Emissions (Tons): 32,155; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.0; 
Carbon Dioxide Emissions (Tons): 14,629,653. 

State: New Jersey; 
Electricity Generation (Megawatt Hours): 9,146,856; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 12.6; 
Sulfur Dioxide Emissions (Tons): 57,806; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 6.3; 
Nitrogen Oxides Emissions (Tons): 28,798; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.1; 
Carbon Dioxide Emissions (Tons): 10,051,576. 

State: New Mexico; 
Electricity Generation (Megawatt Hours): 17,453,290; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 4.2; 
Sulfur Dioxide Emissions (Tons): 36,895; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.7; 
Nitrogen Oxides Emissions (Tons): 49,592; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.1; 
Carbon Dioxide Emissions (Tons): 18,612,310. 

State: New York; 
Electricity Generation (Megawatt Hours): 35,195,389; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 13.0; 
Sulfur Dioxide Emissions (Tons): 228,813; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 3.3; 
Nitrogen Oxides Emissions (Tons): 57,300; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.0; 
Carbon Dioxide Emissions (Tons): 36,715,581. 

State: North Carolina; 
Electricity Generation (Megawatt Hours): 41,162,804; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 12.6; 
Sulfur Dioxide Emissions (Tons): 258,948; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 4.2; 
Nitrogen Oxides Emissions (Tons): 87,450; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.0; 
Carbon Dioxide Emissions (Tons): 41,469,611. 

State: North Dakota; 
Electricity Generation (Megawatt Hours): 4,300,003; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 20.4; 
Sulfur Dioxide Emissions (Tons): 43,911; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.9; 
Nitrogen Oxides Emissions (Tons): 12,657; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.3; 
Carbon Dioxide Emissions (Tons): 5,605,774. 

State: Ohio; 
Electricity Generation (Megawatt Hours): 69,151,066; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 22.8; 
Sulfur Dioxide Emissions (Tons): 789,672; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.4; 
Nitrogen Oxides Emissions (Tons): 188,078; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.0; 
Carbon Dioxide Emissions (Tons): 71,298,574. 

State: Oklahoma; 
Electricity Generation (Megawatt Hours): 6,743,970; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Sulfur Dioxide Emissions (Tons): 0; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 3.8; 
Nitrogen Oxides Emissions (Tons): 12,725; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 0.6; 
Carbon Dioxide Emissions (Tons): 4,352,123. 

State: Oregon; 
Electricity Generation (Megawatt Hours): 0; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Sulfur Dioxide Emissions (Tons): 0; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Nitrogen Oxides Emissions (Tons): 0; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): [Empty]; 
Carbon Dioxide Emissions (Tons): 0. 

State: Pennsylvania;; 
Electricity Generation (Megawatt Hours): 80,866,255; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 20.5; 
Sulfur Dioxide Emissions (Tons): 830,616; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 3.9; 
Nitrogen Oxides Emissions (Tons): 159,062; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.0; 
Carbon Dioxide Emissions (Tons): 83,278,788. 

State: Rhode Island; 
Electricity Generation (Megawatt Hours): 0; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Sulfur Dioxide Emissions (Tons): 0; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Nitrogen Oxides Emissions (Tons): 0; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): [Empty]; 
Carbon Dioxide Emissions (Tons): 0. 

State: South Carolina; 
Electricity Generation (Megawatt Hours): 15,180,903; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 15.9; 
Sulfur Dioxide Emissions (Tons): 121,059; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 4.7; 
Nitrogen Oxides Emissions (Tons): 35,399; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.0; 
Carbon Dioxide Emissions (Tons): 15,772,080. 

State: South Dakota; 
Electricity Generation (Megawatt Hours): 393; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Sulfur Dioxide Emissions (Tons): 0; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Nitrogen Oxides Emissions (Tons): 0.0; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 
Carbon Dioxide Emissions (Tons): 4. 

State: Tennessee; 
Electricity Generation (Megawatt Hours): 41,045,623; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 19.3; 
Sulfur Dioxide Emissions (Tons): 396,165; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.1; 
Nitrogen Oxides Emissions (Tons): 103,751; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.1; 
Carbon Dioxide Emissions (Tons): 43,178,072. 

State: Texas; 
Electricity Generation (Megawatt Hours): 68,938,998; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 1.2; 
Sulfur Dioxide Emissions (Tons): 42,411; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 2.7; 
Nitrogen Oxides Emissions (Tons): 93,228; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 0.7; 
Carbon Dioxide Emissions (Tons): 45,508,059. 

State: Utah; 
Electricity Generation (Megawatt Hours): 2,118,089; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 4.2; 
Sulfur Dioxide Emissions (Tons): 4,462; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 3.4; 
Nitrogen Oxides Emissions (Tons): 3,555; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 0.9; 
Carbon Dioxide Emissions (Tons): 1,978,780. 

State: Virginia; 
Electricity Generation (Megawatt Hours): 27,170,249; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 14.8; 
Sulfur Dioxide Emissions (Tons): 200,460; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 4.9; 
Nitrogen Oxides Emissions (Tons): 66,277; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.1; 
Carbon Dioxide Emissions (Tons): 29,493,051. 

State: Vermont; 
Electricity Generation (Megawatt Hours): 0; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Sulfur Dioxide Emissions (Tons): 0; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Nitrogen Oxides Emissions (Tons): 0; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): [Empty]; 
Carbon Dioxide Emissions (Tons): 0. 

State: Washington; 
Electricity Generation (Megawatt Hours): 0; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Sulfur Dioxide Emissions (Tons): 0; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): [Empty]; 
Nitrogen Oxides Emissions (Tons): 0; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): [Empty]; 
Carbon Dioxide Emissions (Tons): 0. 

State: West Virginia; 
Electricity Generation (Megawatt Hours): 46,981,339; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 18.6; 
Sulfur Dioxide Emissions (Tons): 436,309; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 6.4; 
Nitrogen Oxides Emissions (Tons): 150,433; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.0; 
Carbon Dioxide Emissions (Tons): 47,548,879. 

State: Wisconsin; 
Electricity Generation (Megawatt Hours): 21,430,208; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 10.0; 
Sulfur Dioxide Emissions (Tons): 107,205; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.5; 
Nitrogen Oxides Emissions (Tons): 58,913; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.1; 
Carbon Dioxide Emissions (Tons): 23,606,146. 

State: Wyoming; 
Electricity Generation (Megawatt Hours): 8,734,567; 
Sulfur Dioxide Emissions Rate (Lbs. per Megawatt Hour): 7.8; 
Sulfur Dioxide Emissions (Tons): 34,068; 
Nitrogen Oxides Emissions Rate (Lbs. per Megawatt Hour): 5.2; 
Nitrogen Oxides Emissions (Tons): 22,853; 
Carbon Dioxide Emissions Rate (Tons per Megawatt Hour): 1.2; 
Carbon Dioxide Emissions (Tons): 10,098,931. 

Total: 
Electricity Generation (Megawatt Hours): 1,001,343,104; 
Sulfur Dioxide Emissions (Tons): 6,337,203; 
Nitrogen Oxides Emissions (Tons): 2,358,996; 
Carbon Dioxide Emissions (Tons): 1,008,904,054; 

Note: There was no reported electricity production or emissions from 
older units in Idaho, Oregon, Rhode Island, Vermont, or Washington. 

Source: GAO’s analysis of Platts/RDI data. 

[End of table] 

[End of section] 

Appendix II: GAO Contacts and Staff Acknowledgments: 

GAO Contacts: 

David G. Wood (202) 512-3841: 
Eileen R. Larence (202) 512-6510: 

Acknowledgments: 

In addition to the individuals named above, Michael Hix, Chase Huntley,
Vincent Price, and Laura Yannayon made key contributions to this report.
Important contributions were also made by Cynthia Norris, Frank Rusco,
and Amy Webbink. 

[End of section] 

Footnotes: 

[1] The standards are called New Source Performance Standards and 
establish the maximum allowable emissions from new sources and existing 
sources that undergo modifications. For simplicity, we refer to them as 
“new source standards.” 

[2] We used 1972 as the cutoff date for our analysis—instead of August 
17, 1971—because data on the age of generating units were only 
available for full years. 

[3] A megawatt is one million watts, or enough electricity to power 
about 750 homes. 

[4] Sulfur dioxide and nitrogen oxides can transform into fine 
particles in the atmosphere. Fine particles are a subset of particulate 
matter, a regulated pollutant. 

[5] Ozone, a regulated pollutant, forms when nitrogen oxides react with 
volatile organic compounds in the presence of heat and sunlight. 

[6] In recent years, the Department of Justice and/or EPA have brought 
nine legal actions against the owners of coal-fired power plants, 
alleging violations of New Source Review. As of May 2002, all nine 
cases were in litigation and/or settlement negotiations. EPA and the
Department of Justice settled similar actions in 1999 and 2002. 

[7] The emissions rates are expressed in pounds of emissions per 
British thermal unit (Btu) of energy consumed as fuel by the unit. 

[8] Total electricity generated by older fossil-fuel units was 1.001 
billion megawatt-hours in 2000, compared with 1.398 billion megawatt 
hours generated by newer fossil-fuel units. Electricity generated by 
older units totaled about 28.6 percent of all U.S. electricity 
production, including production by nuclear and renewable sources. 

[9] These regions correspond to EPA Region 3 (Delaware, District of 
Columbia, Maryland, Pennsylvania, Virginia, and West Virginia); Region 
4 (Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, 
South Carolina, and Tennessee); and Region 5 (Illinois, Indiana, 
Michigan, Minnesota, Ohio, and Wisconsin). 

[10] The standards for both pollutants are expressed in pounds of 
pollutant per million British thermal units (Btu) of energy in the 
fuel, and vary depending on the age, size, and type of generating unit. 
The standards used for this analysis ranged from 0.5 to 1.2 pounds of 
sulfur dioxide per million Btu, and from 0.15 to 0.80 pounds of 
nitrogen oxides per million Btu. The 0.15 standard became effective in 
1998. 

[11] See Analysis of Strategies for Reducing Multiple Emissions from 
Power Plants: Sulfur Dioxide, Nitrogen Oxides, and Carbon Dioxide, 
Office of Integrated Analysis and Forecasting, Energy Information 
Administration (SR/OIAF/2000-05, December 2000). 

[End of section] 

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