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Report to Congressional Requesters: 

May 2005: 

Clean Air Act: 

Emerging Mercury Control Technologies Have Shown Promising Results, but 
Data on Long-Term Performance Are Limited: 

[Hyperlink, http://www.gao.gov/cgi-bin/getrpt?GAO-05-612]: 

GAO Highlights: 

Highlights of GAO-05-612, a report to congressional requesters: 

Why GAO Did This Study: 

In March 2005, the Environmental Protection Agency (EPA) issued a rule 
that will limit emissions of mercury—a toxic element that causes 
neurological problems—from coal-fired power plants, the nation’s 
largest industrial source of mercury emissions. Under the rule, mercury 
emissions are to be reduced from a baseline of 48 tons per year to 38 
tons in 2010 and to 15 tons in 2018. 

In the rule, EPA set the emissions target for 2010 based on the level 
of reductions achievable with technologies for controlling other 
pollutants—which also capture some mercury—because it believed emerging 
mercury controls had not been adequately demonstrated. EPA and the 
Department of Energy (DOE) coordinate research on mercury controls. In 
this context, GAO was asked to (1) describe the use, availability, and 
effectiveness of technologies to reduce mercury emissions at power 
plants; and (2) identify the factors that influence the cost of these 
technologies and report on available cost estimates. In completing our 
review, GAO did not independently test mercury controls. GAO provided 
the draft report to DOE and EPA for comment. DOE said that it generally 
agreed with our findings. EPA provided technical comments, which we 
incorporated as appropriate. 

What GAO Found: 

Mercury controls have not been permanently installed at power plants 
because, prior to the March 2005 mercury rule, federal law had not 
required this industry to control mercury emissions; however, some 
technologies are available for purchase and have shown promising 
results in field tests. Overall, the most extensive tests have been 
conducted on technologies using sorbents—substances that bind to 
mercury when injected into a plant’s exhaust. Tests of sorbents lasting 
from several hours to several months have yielded average mercury 
emission reductions of 30-95 percent, with results varying depending on 
the type of coal used and other factors, according to DOE and other 
stakeholders we surveyed. Further, the most recent tests have shown 
that the effectiveness of sorbents in removing mercury has improved 
over time. Nonetheless, long-term test data are limited because most 
tests at power plants during normal operations have lasted less than 3 
months. 

The cost of mercury controls largely depends on several site-specific 
factors, such as the ability of existing air pollution controls to 
remove mercury. As a result, the available cost estimates vary widely. 
Based on modeling and data from a limited number of field tests, EPA 
and DOE have developed preliminary cost estimates for mercury control 
technologies, focusing on sorbents. For example, DOE estimated that 
using sorbent injection to achieve a 70-percent reduction in mercury 
emissions would cost a medium-sized power plant $984,000 in capital 
costs and $3.4 million in annual operating and maintenance costs. If 
this plant did not have an existing fabric filter and chose to install 
one—an option a plant might pursue to increase the efficiency of 
mercury removal and reduce related costs—capital costs would increase 
to about $28.3 million, while annual operating and maintenance costs 
would decrease to about $2.6 million. Most stakeholders generally 
expect costs to decrease as a market develops for the control 
technologies and as plants gain more experience using them. 
Furthermore, EPA officials said that recent tests of chemically 
enhanced sorbents lead the agency to believe that its earlier cost 
estimates likely overstated the actual cost power plants would incur. 

Coal-Fired Power Plant: 

[See PDF for image]

[End of figure]

www.gao.gov/cgi-bin/getrpt?GAO-05-612. 

To view the full product, including the scope and methodology, click on 
the link above. For more information, contact John Stephenson at (202) 
512-3841 or stephensonj@gao.gov. 

[End of section]

Contents: 

Letter: 

Results in Brief: 

Background: 

Mercury Controls Have Not Been Permanently Installed at Power Plants 
but Are Available for Purchase and Have Shown Promising Results in 
Field Tests: 

Mercury Control Costs Depend on a Variety of Factors, and Current 
Estimates Vary Widely: 

Concluding Observations: 

Agency Comments: 

Appendixes: 

Appendix I: Objectives, Scope, and Methodology: 

Appendix II: Availability and Costs of Mercury Monitoring Technology: 

Appendix III: Summary of Field-Scale Tests of Mercury Controls: 

Appendix IV: Summary of Stakeholder Perceptions about Availability of 
Mercury Controls: 

Appendix V: Stakeholder Confidence in Ability of Technologies to 
Achieve Mercury Reductions under Three Scenarios: 

Appendix VI: Sorbent Injection Cost Estimates from EPA and DOE: 

Appendix VII: GAO Contact and Staff Acknowledgments: 

Tables: 

Table 1: Summary of Mercury Control Field Test Data: 

Table 2: Stakeholder Perceptions on Availability of Sorbent 
Technologies: 

Table 3: Stakeholder Perceptions on Availability of Non-Sorbent Mercury 
Controls: 

Table 4: Stakeholder Confidence in Reducing Nationwide Mercury 
Emissions 50 Percent by 2008: 

Table 5: Stakeholder Confidence in Achieving Mercury Reductions of 50 
Percent at Nearly Every Plant by 2008: 

Table 6: Stakeholder Confidence in Reducing Nationwide Mercury 
Emissions 70 Percent by 2008: 

Table 7: Stakeholder Confidence in Achieving Mercury Reductions of 70 
Percent at Nearly Every Plant by 2008: 

Table 8: Stakeholder Confidence in Reducing Nationwide Mercury 
Emissions 90 Percent by 2008: 

Table 9: Stakeholder Confidence in Achieving Mercury Reductions of 90 
Percent at Nearly Every Plant by 2008: 

Table 10: Select EPA Cost Estimates of Sorbent Injection for a 100-
Megawatt Coal-Fired Power Plant, 2003: 

Table 11: Select EPA Cost Estimates of Sorbent Injection for a 975-
Megawatt Coal-Fired Power Plant, 2003: 

Table 12: DOE's Cost Estimates for Sorbent Injection Installed on a 500-
Megawatt Coal Power Plant, 2003: 

Figures: 

Figure 1: Overview of a Coal-Fired Power Plant: 

Figure 2: Sample Layout of Mercury Controls at a Coal-Fired Power 
Plant: 

Figure 3: Stakeholder Perceptions about Availability of Mercury 
Controls: 

Abbreviations: 

ACI: Activated Carbon Injection: 

CEMS: Continuous Emissions Monitoring Systems: 

DOE: Department of Energy: 

EPA: Environmental Protection Agency: 

ESP: Electrostatic Precipitator: 

FDA: Food and Drug Administration: 

FF: Fabric Filter: 

FGD: Flue Gas Desulfurization: 

MACT: Maximum Achievable Control Technology: 

MW: Megawatt: 

NESCAUM: Northeast States for Coordinated Air Use Management: 

NETL: National Energy Technology Laboratory: 

Letter May 31, 2005: 

Congressional Requesters: 

Mercury, a toxic element that poses human health threats, enters the 
environment through natural and human activities, such as volcanic 
eruptions and fuel combustion. Coal-fired power plants release mercury 
into the air when burning coal to generate electricity and were, prior 
to March 2005, the largest unregulated industrial source of mercury 
emissions in the United States.[Footnote 1] The Environmental 
Protection Agency (EPA) estimated that in 1999, the most recent year 
for which data were available, coal-fired power plants within the 
United States emitted 48 tons of mercury into the air, or about 42 
percent of the total man-made emissions nationwide.[Footnote 2] The 
Clean Air Act Amendments of 1990 required EPA to study the 
environmental and health effects of hazardous air pollutants from coal-
fired power plants and determine whether it was "appropriate and 
necessary" to regulate emissions of these pollutants. 

In 2000, the agency determined that it was appropriate and necessary to 
regulate emissions of mercury, a hazardous air pollutant, from coal-
fired power plants by requiring these plants to meet specific emissions 
standards reflecting the application of control technology (the 
"technology-based" approach).[Footnote 3] In January 2004, EPA issued a 
proposed rule with two options for controlling mercury from power 
plants--the technology-based approach and an alternative approach that 
would set a national cap on mercury emissions and allow power plants 
flexibility either to achieve reductions or to purchase allowances from 
plants that achieved excess reductions (the "cap-and-trade" 
option).[Footnote 4]

In March 2005, EPA revised its finding that it was appropriate and 
necessary to regulate mercury emissions from power plants under the 
technology-based approach and issued a final rule based on the cap and 
trade option that established a mercury cap of 38 tons for 2010 and a 
second phase cap of 15 tons for 2018.[Footnote 5] Although power plants 
were not previously required to control mercury emissions, some already 
captured mercury as a side benefit of using controls designed to reduce 
other pollutants such as sulfur dioxide. In developing the rule, EPA 
determined that technologies specifically intended to capture mercury 
were not adequately demonstrated and therefore were not "commercially 
available." As a result, the agency decided that it could not 
reasonably impose requirements to use these technologies in the near-
term and set emissions targets for 2010 based on the level of mercury 
control it expects to result as a side benefit of another rule it 
issued in March 2005--the Clean Air Interstate Rule (the interstate 
rule)--that calls for further reductions in emissions of nitrogen 
oxides and sulfur dioxide. 

Controlling mercury from power plants poses unique challenges because 
it is emitted in low concentrations, making removal difficult, and in 
several different forms, some of which are harder to capture than 
others. In addition, the relative ease of removal varies from plant to 
plant depending upon such site-specific factors as the type of coal 
burned.[Footnote 6] EPA and the Department of Energy (DOE) coordinate 
research and development of mercury controls, with EPA conducting small-
scale research on new technologies, while DOE partners with the power 
industry and other stakeholders to conduct field tests of mercury 
control technologies at power plants. 

The DOE field tests have focused on (1) mercury controls known as 
sorbent injection technologies, in which powdered substances (known as 
sorbents) that bind to mercury are injected into a plant's exhaust; (2) 
enhancements to existing controls for other pollutants to increase 
mercury removal; (3) multipollutant controls, which simultaneously 
capture mercury and other pollutants; and (4) oxidation technologies, 
which convert mercury to a chemical form that is easier to remove. As 
of February 2005, 13 of DOE's field tests were completed and 26 were 
planned or not yet completed. 

In this context, you asked us to (1) describe information on the use, 
availability, and effectiveness of technologies to reduce mercury 
emissions at power plants; and (2) identify the factors that influence 
the cost of these technologies and report on available cost estimates. 
To respond to these objectives, we reviewed data about technologies 
specifically designed to reduce mercury, including modifications to 
pollution controls already in use that would target and improve mercury 
capture.[Footnote 7] We included test data on mercury controls used in 
field-scale tests but did not include test data on controls that were 
at earlier stages of development. We surveyed 59 key stakeholders--
including mercury control vendors, representatives of the coal-fired 
power industry, technology researchers, and government officials--and 
received 40 responses. In addition, we reviewed technical documents 
addressing the performance of mercury controls and discussed technology 
research and development with 14 key stakeholders who view mercury 
reduction from a policy perspective. We did not independently test 
mercury control technologies. Finally, we interviewed vendors and 
researchers of mercury emissions monitoring technology to obtain and 
analyze information on the availability and reliability of mercury-
monitoring devices; this information is presented in appendix II. (See 
app. I for a more detailed description of the scope and methodology of 
our review.) We performed our work between May 2004 and May 2005 in 
accordance with generally accepted government auditing standards. 

Results in Brief: 

Mercury controls have not been permanently installed at power plants 
because, prior to the March 2005 mercury rule, federal law had not 
required this industry to control mercury emissions; however, some 
technologies are available for purchase and have shown promising 
results in field tests. Overall, tests of varying duration of the most 
developed mercury control, sorbent injection, have achieved average 
mercury reductions of 30 to 95 percent, with results depending on the 
rank of coal burned and other factors, according to DOE and other 
stakeholders we surveyed. More recent DOE-funded monthlong tests, 
particularly those for chemically enhanced sorbents, have shown average 
removal rates of over 90 percent. However, data on the long-term 
performance of mercury controls or the effect that they have on the 
overall reliability and efficiency of power plants are limited, 
especially for plants using low-rank coals, because most field tests 
have lasted less than 3 months. Ongoing tests may better inform 
stakeholders within the next year about the longer-term capabilities of 
mercury controls for these coals. 

The cost to install and operate mercury controls depends on a number of 
factors, including the extent to which controls already in place to 
reduce other pollutants also reduce mercury emissions. As a result, 
cost estimates vary widely. Available EPA and DOE cost estimates for 
mercury controls have focused primarily on sorbent injection and were 
based on modeling and data from a limited number of field tests, making 
them preliminary and uncertain. Nonetheless, DOE estimated that using 
sorbent injection to achieve a 70 percent reduction in mercury 
emissions would cost a medium-sized power plant--one that has the 
capacity to generate 500 megawatts of electricity and operates for 
about 80 percent of the time over the course of a year--$984,000 in 
capital costs and $3.4 million in annual operating and maintenance 
costs. If this same plant were to install a supplemental fabric filter-
-an option a plant might pursue to increase the efficiency of mercury 
removal and reduce related costs--capital costs would increase to about 
$28.3 million, while annual operating and maintenance costs would 
decrease to about $2.6 million. Regardless of the exact magnitude of 
costs, most stakeholders we contacted generally expect mercury control 
technologies to cost less over time as a market develops for the 
controls and as plants gain more experience using them. Furthermore, 
EPA officials said that recent tests of chemically enhanced sorbents 
lead the agency to believe that its earlier cost estimates likely 
overstated the actual costs power plants would incur. 

We provided a draft of this report to DOE and EPA for review and 
comment. DOE said that it generally agreed with our findings. EPA's 
Office of Air and Radiation and Office of Research and Development 
provided technical comments, which we incorporated as appropriate. 

Background: 

Mercury enters the environment through natural and man-made sources, 
including volcanoes, chemical manufacturing, and coal combustion, and 
poses ecological threats when it enters water bodies, where small 
aquatic organisms convert it into its highly toxic form--methylmercury. 
This form of mercury may then migrate up the food chain as predator 
species consume the smaller organisms. Through a process known as 
bioaccumulation, predator species may consume and store more mercury 
than they can metabolize or excrete. 

Fish contaminated with methylmercury may pose health threats to people 
that rely on fish as part of their diet. Mercury harms fetuses and can 
cause neurological disorders in children, including poor performance on 
behavioral tests, such as those measuring attention, motor and language 
skills, and visual-spatial abilities (such as drawing). The Food and 
Drug Administration (FDA) and EPA recommend that expectant or nursing 
mothers and young children avoid eating swordfish, king mackerel, 
shark, and tilefish and limit consumption of other potentially 
contaminated fish. These agencies also recommend checking local 
advisories about recreationally caught freshwater and saltwater fish. 
According to EPA, 45 states issued mercury advisories in 2003 (the most 
recent data available). 

According to the United Nations Environment Program, global mercury 
emissions are uncertain but fall within an estimated range of 4,850 to 
8,267 tons per year. Of this total, EPA estimates that man-made sources 
in the United States emit about 115 tons per year, with about 48 tons 
emitted by power plants. Because mercury can circulate for long periods 
of time and be transported thousands of miles before it gets deposited, 
it is difficult to link mercury accumulation in the food chain with 
individual emission sources. 

The United States has 491 power plants that rely in whole or in part on 
coal for electricity generation, and these plants produced 52 percent 
of all electricity generated in 2004, according to DOE's most recent 
data. These plants generally operate by burning coal in a boiler to 
convert water into steam, which in turn drives turbines that generate 
electricity. Figure 1 provides a general overview of a power plant's 
layout. 

Figure 1: Overview of a Coal-Fired Power Plant: 

[See PDF for image] 

[End of figure] 

Power plants burn at least one of the three primary coal ranks--
bituminous, subbituminous, and lignite--and plants may burn a blend of 
different coals, according to DOE. Of all coal burned by power plants 
in the United States in 2004, DOE estimates that about 46 percent was 
bituminous, 46 percent was subbituminous, and 8 percent was lignite. 
The amount of mercury in coal and the relative ease of its removal 
depend on a number of factors, including the geographic location where 
it was mined and chemical variation within and among coal ranks. 

Coal combustion releases other harmful air pollutants in addition to 
mercury, including sulfur dioxide and nitrogen oxides.[Footnote 8] EPA 
has regulated these pollutants since 1995 and 1996, respectively, 
through its program intended to control acid rain. In addition, the 
March 2005 interstate rule will require further cuts in these 
pollutants beginning in 2009.[Footnote 9] To comply with these and 
other regulations, the coal-fired power industry has installed a 
variety of technologies that, while intended to control nitrogen 
oxides, particulate matter, or sulfur dioxide, may also affect or 
enhance mercury capture. Examples of such technologies include 
selective catalytic reduction (SCR) for nitrogen oxides, electrostatic 
precipitators (used by about 80 percent of all facilities) and fabric 
filters (used by the remaining 20 percent) to control particulate 
matter and wet or dry scrubbers to remove sulfur dioxide. 

EPA estimates that power plants capture about 27 tons of mercury each 
year, primarily through the use of controls for other pollutants. In 
general, the exhaust from coal combustion (called flue gas) exits the 
boiler and may flow through a device intended to control nitrogen 
oxides before entering the particle control device and then through a 
scrubber prior to release from the smokestack. The combination of these 
devices in use at power plants differs greatly among facilities and is 
likely to change as a result of the interstate rule, which, according 
to EPA, will result in additional installations of equipment to control 
nitrogen oxides and sulfur dioxide. EPA believes that the steps power 
plants will take to control nitrogen oxides and sulfur dioxide under 
the interstate rule will enable them to meet the first phase mercury 
cap of 38 tons beginning in 2010.[Footnote 10] As noted above, EPA 
determined that mercury control technologies were not commercially 
available and that the agency could not reasonably impose requirements 
to use them in the near-term. 

Nonetheless, a number of mercury control technologies have been 
developed over the past several years as a result of public and private 
investments in research and development, and these technologies 
generally fall into the following categories: 

* Sorbent (carbon-based, chemically enhanced carbon-based, and non-
carbon based). This technology involves injecting a powdered substance 
(sorbent) into the flue gas that binds to mercury prior to collection 
in a particle control device. Regardless of the chemical composition of 
the sorbent, this technology involves adding a silo or other structure 
containing the sorbent and a system that injects the sorbent into ducts 
that carry the flue gas. 

* Enhancements to existing controls for other pollutants to increase 
mercury capture. This class of technologies focuses on retrofitting 
existing controls for other pollutants to improve their ability to 
capture mercury. Examples of enhancements include adding sorbents to 
wet scrubbers used for sulfur dioxide removal or modifying selective 
catalytic reduction devices used to reduce nitrogen oxides. 

* Multipollutant controls. This class of technologies is designed from 
the outset to simultaneously control or enhance the removal of multiple 
pollutants, such as mercury, nitrogen oxides, or sulfur 
dioxide.[Footnote 11] These technologies may also use sorbents. 

* Oxidation technologies. This class includes methods, chemicals, or 
equipment designed to oxidize mercury into a form that is more readily 
captured. 

* Other technologies. This category includes other technologies that 
capture mercury using approaches such as removing mercury from coal 
prior to combustion and fixed adsorption devices that rely on precious 
metals such as gold to separate mercury from flue gas. 

The intended location of these technologies in a power plant's overall 
layout may vary. As shown in figure 2, some may be located between the 
boiler and the particulate matter collection device, while others may 
be located further downstream in a plant's process. This figure also 
shows that some plants can either install sorbent injection upstream of 
the existing particulate matter removal device or downstream of the 
device using a supplemental filter to collect the spent sorbent, 
keeping it separate from the fly ash collected in the particulate 
matter collection device. The latter configuration may be relevant for 
those facilities that sell their fly ash as a raw material for use in 
other applications, such as cement manufacturing, because carbon-based 
sorbent can render fly ash unsuitable for some of these applications. 
According to EPA, power plants sell about 35 percent of their fly ash 
for use in other applications, with 15 percent going to uses, such as 
cement manufacturing, where carbon contamination could pose a problem. 

Figure 2: Sample Layout of Mercury Controls at a Coal-Fired Power 
Plant: 

[See PDF for image] 

[End of figure] 

The Department of Energy's (DOE) National Energy Technology Laboratory 
partners with the private sector to evaluate the use of mercury control 
technologies at power plants in tests lasting up to 5 months. The 
testing program focuses on mercury controls, such as sorbent injection, 
and ways to better and more consistently capture mercury with 
technologies for other pollutants. Participants in DOE's program 
evaluate concepts in laboratories and develop promising technologies in 
progressively larger-scale applications, including actual power 
plants.[Footnote 12] The duration of the tests that have been completed 
has varied from several hours to 5 months, with most of the completed 
DOE-funded tests lasting between 1 week and several months.[Footnote 
13] The most recent phase of DOE testing has focused on the longer-term 
performance of mercury control technologies. Appendix III provides more 
information on the DOE tests completed, ongoing, or planned as of 
February 2005. 

Mercury Controls Have Not Been Permanently Installed at Power Plants 
but Are Available for Purchase and Have Shown Promising Results in 
Field Tests: 

Power plants in the United States do not currently use mercury 
controls, but some technologies are available for purchase and have 
shown promising results in full-scale tests in power plants. These 
tests have shown that mercury controls known as sorbent technologies--
which involve injection of a powdered material that binds to mercury in 
the plant's exhaust--have shown the greatest effectiveness in removing 
mercury during tests at power plants. However, long-term test data are 
limited because most of these tests have lasted less than 3 months. 

Mercury Controls Are Not Currently Used by Power Plants, but Some 
Technologies Are Available for Purchase: 

According to all 40 survey respondents, coal-fired power plants were 
not, as of November 2004, using mercury controls, although several 
plants have subsequently announced plans to install them. The coal-
fired power industry has not used mercury controls because, prior to 
EPA's March 2005 rule, federal law had not required mercury emissions 
reductions at power plants.[Footnote 14] In fact, most of the power 
industry survey respondents (13 of 14) cited uncertainty about future 
regulations as one of the top three reasons for not installing mercury 
controls. Thus, in the absence of federal requirements to reduce 
mercury emissions, limited demand existed for mercury controls. 

We found that although some mercury controls, such as activated carbon 
injection, are currently available for purchase from vendors, 
perceptions about their availability vary widely among stakeholders, 
primarily because stakeholders do not consistently define 
"availability." That is, some stakeholders believe that mercury 
controls become available when they have been demonstrated in long-term 
tests under normal commercial operations, rather than when they are 
available for purchase. Thus, some stakeholders' views on availability 
reflect more of a judgment about the proven effectiveness of a control 
technology than their availability for purchase.[Footnote 15] In this 
context, we found that views regarding the availability of mercury 
controls generally varied by stakeholder group and by the type of 
control. A greater portion of the vendors described mercury controls as 
available than either of the other two groups we surveyed, with the 
power industry group citing these controls as available least 
frequently. As shown in figure 3, the stakeholders were overall most 
optimistic about the availability of activated carbon injection 
technologies, followed by multipollutant controls and enhancements to 
existing controls for other pollutants. 

Figure 3: Stakeholder Perceptions about Availability of Mercury 
Controls: 

[See PDF for image] 

Note: This figure is based on responses from the stakeholders that 
participated in either our surveys (40) or structured interviews (14). 
In asking survey respondents and interview participants about their 
views on the availability of all mercury controls, we categorized 
sorbent injection technologies as activated carbon, chemically enhanced 
carbon, and non-carbon injection in order to reflect the research and 
development of various sorbent materials. 

[End of figure] 

Appendix IV provides more detailed information on stakeholder 
perceptions of the availability of mercury controls. 

In evaluating the availability of mercury controls prior to finalizing 
the March 2005 mercury rule, EPA found that mercury controls were 
available for purchase but concluded that they had not been 
sufficiently demonstrated in long-term tests, and therefore were not 
available for permanent installation at power plants before 2010. As a 
result, EPA set the 2010 mercury reduction targets at a level that 
power plants could achieve as a side benefit of using technologies for 
other pollutants that the agency expects many plants will install to 
comply with the interstate rule, and set more stringent limits for 
2018. Thus, power plants will not need to install mercury-specific 
controls until well after 2010. According to an EPA white paper 
assessing test results as of February 2005, the agency expects that 
mercury control technologies will be available for commercial 
application on most, if not all, key combinations of coal type and 
control technology to provide mercury removal levels between 60 and 90 
percent after 2010 and between 90 and 95 percent in the 2010-2015 time 
frame.[Footnote 16]

Some Mercury Controls Have Shown Promising Results in Short-Term Field 
Tests, but Data on Long-Term Performance Are Limited: 

Because mercury controls have not been permanently installed at power 
plants, the data on the performance of these technologies come from 
field tests. We obtained data from 29 completed field tests, including 
13 which were part of DOE's mercury control research and development 
program, and 16 other tests identified by survey respondents.[Footnote 
17] Most of the available test data (21 of 29 tests) related to the 
effectiveness of sorbents. According to DOE and EPA, the tests have 
shown promising results, although the extent of mercury removal varies 
at each plant. 

Tests of varying duration have identified sorbent technologies as the 
most developed mercury controls, which show promising results in 
achieving high mercury reductions. For example, tests of activated 
carbon and chemically enhanced carbon-based sorbents at power plants 
using a variety of air pollution controls have shown average reductions 
of 30 to 95 percent overall, providing the following average mercury 
reductions for each coal type:[Footnote 18]

* 70-95 percent average removal on bituminous coals;

* 30-90 percent average removal on subbituminous coals;

* 63-70 percent average removal on lignite coals; and[Footnote 19]

* 94 percent removal on blends of bituminous/subbituminous coals. 

As the scale and duration of testing has increased, researchers have 
gained a better understanding of site-specific variables that affect 
results, and more recent full-scale, monthlong tests, particularly 
those using chemically enhanced carbon-based sorbents, have shown 
sustained high removal rates. For example, a monthlong test conducted 
in 2004 showed that a chemically enhanced sorbent reduced mercury 
emissions from a primarily subbituminous blend of coal by 94 percent, 
and a monthlong test of another chemically enhanced sorbent at a 
different plant burning subbituminous coal achieved a 93 percent 
reduction. 

A number of the stakeholders we surveyed pointed out that the results 
of a particular test cannot be generalized or extrapolated to estimate 
potential reductions at other power plants because the reductions 
achieved during a test may have resulted in part from factors unique to 
that facility, such as its size, the type of boiler used, the 
temperature of its flue gas, or the combination of controls for other 
pollutants. For example, available data show that the extent of mercury 
reduction achieved by sorbent injection at facilities using 
electrostatic precipitators depends largely on the location of these 
devices at the plant. The location of an electrostatic precipitator in 
turn affects the temperatures of the flue gas entering the device, with 
more mercury captured at cooler temperatures. Thus, the results 
achieved at a particular plant may not serve as a reliable indicator of 
the performance of that control at all plants. 

DOE's research and development program has funded tests of mercury 
controls on each coal type in light of its and EPA's conclusions that 
the form of mercury emitted--which varies by coal type--and other 
chemical variations among coal types, such as chlorine content, can 
have an impact on a control's removal effectiveness. For example, lower 
removal rates in activated carbon injection tests have occurred 
primarily at plants burning low rank coal or at plants with existing 
controls that are less conducive to mercury removal. One university-
based researcher attributes the challenge of mercury reductions on 
lignite--a low rank coal--to its chemical composition, but believes 
that chemically enhanced sorbents and special additives can improve the 
ability of the sorbent to bind to this form of mercury, thereby 
addressing this problem. The more recent mercury removal results we 
reviewed tended to support this view as monthlong tests using 
chemically enhanced carbon-based sorbents achieved average reductions 
of 70 percent or greater on low-rank coals, including lignites, 
suggesting that this technology may achieve high-level mercury 
reductions from low-rank coals (See app. III for more information on 
these results). 

Since most of the field tests have focused on sorbent injection, fewer 
data are available on the performance of non-sorbent mercury controls, 
such as multipollutant controls, enhancements to existing controls, and 
mercury oxidation technologies. Results from 11 of the 19 tests of such 
controls were not yet available (9 of the tests were not planned to 
begin until after February 2005). The few available results show that 
average mercury removal achieved by multipollutant controls and 
enhancements has ranged from about 50 percent to 90 percent. The field 
tests of mercury oxidation technologies, multipollutant controls, 
enhancements and other non-sorbent technologies, lasting several days 
to several months, have included all coal types, but most (7 of 10) to 
date have focused on bituminous coal. In addition, a future DOE project 
will fund a test of a multipollutant control on a plant burning 
subbituminous coal and three tests of mercury controls, including 
mercury oxidation and enhancements, on plants burning lignite 
coal.[Footnote 20]

Stakeholders Generally Agree That Sorbent Injection Is the Most 
Promising Control and That Some Additional Tests Are Needed: 

As noted above, EPA determined as part of its March 2005 mercury rule 
that it could not reasonably impose requirements that would force the 
use of mercury-specific controls before 2010. Specifically, EPA 
believes that chemically enhanced carbon-based sorbents could reduce 
mercury emissions at a broad spectrum of plants but regards long-term 
testing as necessary in order to evaluate (1) the mercury removal 
performance of technologies when operated continuously for more than 
several months at a time; and (2) the impact that these controls have 
on a plant's overall efficiency and operations. Furthermore, DOE 
officials have said that while sorbent injection holds much promise, it 
is unwise to depend solely on one approach for mercury control in part 
because the site-specific variables at each power plant affects the 
performance of mercury controls. DOE has concluded that it will be 
necessary to build a broad portfolio of mercury control options. 

Likewise, technical papers and presentations about the field tests by 
research and development participants express a high degree of 
confidence in the capability of sorbents, particularly chemically 
enhanced carbon-based sorbents, but also suggest the need for 
additional evaluation of the impact of these controls, if any, on the 
efficiency and reliability of power plants. For example, a paper 
written by a sorbent vendor conducting DOE-funded tests concluded that 
recent monthlong tests of chemically enhanced carbon-based sorbent 
injection have shown high mercury removal at plants that burn 
subbituminous coals, but also discussed concerns about the long-term 
use of this control on a power plant's operations. This vendor 
concluded that although these tests did not show any adverse effects 
resulting from the chemically enhanced carbon-based sorbent, concerns 
and issues surrounding the contamination of fly ash that can render it 
unsuitable for sale for certain applications have not yet been 
resolved. With regard to potential adverse impacts at plants, no 
serious adverse effects have been associated with sorbent injection 
tests lasting up to 1 month in duration, according to EPA. 

To provide additional perspective on the expected long-term performance 
of mercury controls, we asked survey respondents to indicate whether 
they believed power plants could use mercury controls to achieve 
industrywide mercury reductions of 50, 70, or 90 percent by 
2008.[Footnote 21] We also asked the respondents whether their 
perceptions would differ if the reductions were averaged across the 
industry (as in an emissions trading program) or if they were required 
at each plant. We found that many survey respondents (22 of the 38 
answering this question) were confident in the ability of power plants 
to achieve a 50 percent reduction by 2008 regardless of whether the 
reductions were achieved at each plant or averaged across the 
industry.[Footnote 22] EPA set the mercury emissions cap for 2010 based 
on a 50 percent reduction from the 75 tons in coal. 

The stakeholders were progressively less confident in the ability of 
plants to achieve 70 and 90 percent reductions by 2008. For the 70 
percent reduction scenario, stakeholders were more confident in the 
ability of plants to achieve this reduction averaged across the 
industry rather than at each plant; 16 stakeholders described 
themselves as confident or very confident in the ability of plants to 
achieve this level of reduction nationwide, while 21 described 
themselves as less confident or not at all confident. For the 90 
percent scenario, the vast majority of the survey respondents (33 of 38 
that answered this question) described themselves as not at all 
confident or less confident in the ability of plants to achieve this 
level of reduction nationwide by 2008. Appendix V summarizes the survey 
responses for each of the three scenarios. 

Furthermore, we asked the 40 survey respondents to identify additional 
testing needed to assess the ability of mercury control technologies to 
effectively and reliably reduce mercury emissions by 70 percent. Most 
of the survey responses (40 of 45)[Footnote 23] showed that 
stakeholders believe that some additional testing is needed for at 
least one technology. For example, the 14 power industry respondents 
said that additional testing is needed for sorbent injection. In 
addition, 3 of the 4 carbon-based sorbent vendors answering this 
question as well as 9 of the 12 researchers and government officials 
believed that some additional testing is needed to show that carbon-
based sorbent injection would reliably and effectively achieve mercury 
reductions of 70 percent. 

Three policy stakeholders representing the power industry believed that 
more tests are needed to evaluate factors such as the performance of 
controls on low-rank coals, the impact on small power plants, and the 
ability of plants to use mercury controls without compromising 
electricity generation. Several of the power industry respondents 
expressed concern about the potential for mercury controls to interfere 
with a plant's overall efficiency or cause malfunctions, and a power 
industry representative pointed out that such disruptions are a concern 
because power plants cannot store electricity for use as a backup when 
they experience technical problems. Information from ongoing and 
planned long-term tests will provide important information on both the 
long-term performance of mercury controls and the effect, if any, that 
these controls have on the efficiency or reliability of power plants. 

In addition, several plants have recently announced plans to install 
mercury controls to comply with either state permit requirements or the 
terms of legal settlements. For example, a power plant in New Mexico 
announced in March 2005 that it would install sorbent injection within 
the next 2 years to reduce mercury emissions as part of a settlement 
agreement with two environmental groups. A plant representative stated 
that while he believes sorbent technology "is not that advanced … it is 
advanced enough to use it to reduce mercury emissions" at the power 
plant. Another power plant currently under construction in Iowa has a 
state air pollution permit requiring the company to control mercury 
emissions and is installing sorbent injection technology. The company 
expects to reduce mercury emissions from subbituminous coal by 83 
percent. Finally, under an agreement with the state of Wisconsin, a 
Michigan power plant owned by a Wisconsin-based company has begun to 
install a multipollutant control that will use sorbent injection to 
reduce mercury and other pollutants. 

Mercury Control Costs Depend on a Variety of Factors, and Current 
Estimates Vary Widely: 

The estimated costs to install and operate mercury controls vary 
greatly and depend on a number of site-specific factors, including the 
amount of sorbent used (if any), the ability of existing air pollution 
controls to remove mercury, and the type of coal burned. EPA and DOE 
have developed the most comprehensive estimates available for mercury 
controls based on modeling and data from a limited number of field 
tests, making them both preliminary and uncertain.[Footnote 24] These 
estimates, as well as other available estimates, focus on sorbent 
injection, the most developed mercury control technology. Estimated 
costs for sorbent injection vary greatly depending on whether 
facilities achieve mercury reduction targets by using this technology 
in combination with their existing air pollution control devices or 
instead add fabric filters to collect the spent sorbent. Regardless of 
the exact costs of the controls, most of the stakeholders we contacted 
generally expect the costs to decrease over time. 

Cost Estimates Depend on Several Site-Specific Factors: 

The available cost estimates are projections based on a limited number 
of tests, primarily of activated carbon injection. The cost estimates 
we reviewed show that the total costs of installing and operating 
mercury controls vary depending on factors such as sorbent consumption, 
the ability of existing air pollution controls to remove mercury, and 
the type of coal burned. We discuss each of these factors in more 
detail below: 

* Sorbent consumption: The amount of sorbent that a facility needs to 
use greatly influences control cost estimates. According to DOE, 
sorbent consumption levels for activated carbon injection technology 
directly relate to the desired level of mercury control. Further, while 
increasing the amount of carbon injected increases mercury removal, the 
performance of the carbon eventually levels off, requiring increasingly 
greater amounts of carbon to achieve an incremental mercury reduction. 
For example, test data from a plant burning subbituminous coal show 
that more than twice as much sorbent would be needed to remove 60 
percent of the mercury from the plant's flue gas than to remove 50 
percent. Therefore, the cost of the activated carbon can increase 
dramatically, depending on the desired level of mercury removal and the 
type of coal burned. 

* Other air pollution controls already installed: The air pollution 
controls already installed at a facility--especially fabric filters and 
electrostatic precipitators used for controlling particulate matter--
can have a major effect on the cost of controlling mercury because some 
of these devices already remove varying amounts of mercury. For 
example, DOE's tests have shown that fabric filters generally remove 
more mercury than electrostatic precipitators. Thus, facilities with 
fabric filters may already remove enough mercury to achieve a desired 
or required level of reduction. However, plants that do not have an 
existing fabric filter and choose to install one may incur significant 
costs due to their high capital expense. Additionally, EPA believes 
that controls for other pollutants some plants will install to comply 
with the interstate rule--such as selective catalytic reduction to 
control nitrogen oxides and wet scrubbers to control sulfur dioxide--
will result in further mercury capture. Therefore, the combination of 
other air pollution controls may reduce or in some cases eliminate the 
need for a plant to install mercury-specific controls to reduce its 
mercury emissions. As noted above, EPA based its mercury reduction 
goals for 2010 to 2018 on the level of control it expects plants will 
achieve with controls for these other pollutants. 

* Type of coal burned: According to EPA, the amount of mercury captured 
by a given control technology is generally higher for plants burning 
bituminous coals than for those burning subbituminous coals. This 
difference arises because the flue gas from bituminous coal contains 
higher levels of substances that facilitate mercury capture. Along 
these lines, DOE's cost estimates assume that an electrostatic 
precipitator will capture 36 percent of mercury from plants that burn 
bituminous coal, but none of the mercury from plants that burn 
subbituminous coal. Thus, DOE estimated that mercury removal costs are 
higher for subbituminous-fired plants than bituminous-fired plants. 

Available Mercury Control Cost Estimates Are Preliminary and Vary 
Greatly: 

Most of the available cost estimates for mercury control focus on 
sorbent injection, the most developed technology. DOE and EPA have 
developed comprehensive cost estimates; however, they are preliminary 
and, in EPA's case, based on model plants rather than actual power 
plants. Further, while DOE developed its estimates from tests in power 
plants, the agency indicated that its mercury control costs may be off 
by as much as 30 percent in either direction because (1) the estimates 
were developed from a limited data set of relatively short-term tests 
and thus are highly uncertain, and (2) they are based on a number of 
assumptions that, if changed, would result in significantly different 
estimates. According to DOE, further testing of sorbent injection for a 
variety of coals is needed to accurately assess the costs of 
implementing the technology throughout the United States. In addition, 
EPA's and DOE's cost estimates were published in October and November 
2003, respectively, and do not reflect the more recent test data. For 
example, more recent field tests with chemically enhanced sorbents have 
shown that these sorbents may be more efficient at removing mercury 
than the sorbents used in earlier tests. Thus, chemically enhanced 
sorbents may achieve a high level of mercury removal using less sorbent 
and without the high capital cost of installing a fabric filter. DOE 
expects to issue revised cost estimates which will reflect lower costs 
based on recent testing. As a result, the available cost estimates may 
not accurately reflect the costs that power plants would incur if they 
chose to install mercury controls. 

In addition, the two agencies' cost estimates relied on different 
assumptions and are not directly comparable. Most notably, the two 
agencies based their cost estimates on plants of different size and 
made varying assumptions about the percentage of time that an average 
plant operates (called capacity factor). For example, EPA conducted its 
modeling for 100-and 975-megawatt plants, while DOE based its estimates 
on a 500-megawatt plant.[Footnote 25] As a result, EPA provided a wider 
range of cost estimates. Furthermore, EPA assumed a plant capacity 
factor of 65 percent, while DOE assumed an 80 percent capacity factor, 
which resulted in higher operating costs in the DOE estimates.[Footnote 
26] Additionally, based on available data for plants with an existing 
electrostatic precipitator that burn bituminous coal, EPA's modeling 
predicted the existing control equipment would achieve a 50 percent 
mercury removal without sorbent injection, while DOE assumed that this 
configuration would remove no more than 36 percent of mercury and that 
sorbent injection was needed even for achieving 50 percent mercury 
removal.[Footnote 27]

Although the DOE and EPA estimates reflect different assumptions as 
discussed above, we are providing the two agencies' cost estimates for 
achieving a 70 percent mercury reduction at a bituminous-fired coal 
power plant under two scenarios (using an existing electrostatic 
precipitator and installing a supplemental fabric filter) to provide a 
perspective on the costs power plants could incur to install sorbent 
injection technologies. 

* For a 100-megawatt plant using an existing electrostatic 
precipitator, EPA estimated that capital costs would total $527,100 
($5.27 per kilowatt, 2003 dollars), and the operating and maintenance 
costs would total $531,820 annually for a plant operating at 65 percent 
capacity ($0.93 per megawatt-hour).[Footnote 28] Alternatively, if this 
plant were to install a supplemental fabric filter, the capital costs 
would increase to about $5.8 million ($57.73 per kilowatt) and the 
operating and maintenance costs would decrease to $171,959 annually 
($0.30 per megawatt-hour). 

* For a 500-megawatt plant using an existing electrostatic 
precipitator, DOE estimated the capital costs would total $984,000 
($1.97 per kilowatt), and the annual operating and maintenance costs 
would total about $3.4 million ($0.97 per megawatt-hour) for a plant 
operating at 80 percent capacity (2003 dollars). Alternatively, if this 
plant were to install a supplemental fabric filter, the capital costs 
would increase to about $28.3 million ($56.53 per kilowatt), and the 
operating and maintenance costs would decrease to about $2.6 million 
annually ($0.74 per megawatt-hour). 

* For a 975-megawatt plant using an electrostatic precipitator, EPA 
estimated that capital costs would total about $2.4 million ($2.47 per 
kilowatt), and the operating and maintenance costs would be about $5.1 
million annually for a plant operating at 65 percent capacity ($0.92 
per megawatt-hour). Alternatively, if this plant were to install a 
supplemental fabric filter, the capital costs would increase to about 
$35.4 million ($36.32 per kilowatt), and the operating and maintenance 
costs would decrease to about $1.6 million annually ($0.30 per megawatt-
hour). 

These data show that DOE estimated lower capital costs per unit of 
power generating capacity than EPA, while EPA estimated slightly lower 
operating and maintenance costs than DOE. This may result from the fact 
that EPA assumed higher rates of mercury removal with existing controls 
than DOE, as well as DOE's use of a higher plant capacity factor than 
EPA. Appendix VI provides additional information on EPA's and DOE's 
cost estimates for sorbent injection control technologies. 

According to EPA, the costs of sorbent injection technologies to 
control mercury emissions are very small compared to other air 
pollution control equipment when other retrofits, such as the addition 
of fabric filters, are not required. EPA also reports that the fixed 
operating costs for these systems are also relatively low, stemming 
from the simplicity of the equipment. In EPA's rulemaking documents, 
the agency said that in light of the more recent tests of chemically 
enhanced sorbents, their earlier estimates likely overstated the actual 
costs power plants would incur. DOE officials said they shared this 
view. 

EPA also estimated costs for multipollutant controls, including 
advanced dry scrubbers. Although these controls cost substantially more 
than sorbent injection, they would provide additional benefits by 
controlling other types of pollutants such as nitrogen oxides and 
sulfur dioxide.[Footnote 29] EPA regarded cost information for 
multipollutant controls as preliminary, because there had been limited 
commercial experience with these technologies in the United States. In 
part because the agency estimated a range of capital and operating 
costs for each scenario, EPA's estimates of the cost of these 
technologies varied widely.[Footnote 30] For example, for advanced dry 
scrubbers, EPA estimated the capital costs as $115.46 to $243.08 per 
kilowatt, with costs per kilowatt generally higher for smaller 
plants.[Footnote 31] For 100-megawatt and 975-megwatt plants, capital 
costs could be as low as $16.2 million and as high as $168.7 million 
respectively. EPA estimated operating and maintenance costs for a 100-
megawatt plant to be between $1.1 million and $1.3 million per year, 
assuming a plant capacity factor of 65 percent (or between $1.93 and 
$2.35 per megawatt-hour). For a 975-megawatt plant, operating and 
maintenance costs were estimated to be between $9.3 million and $37.5 
million per year, assuming a plant capacity factor of 65 percent (or 
between $1.68 to $6.76 per megawatt-hour). 

In addition to the cost estimates from EPA and DOE, we surveyed 
technology vendors, representatives of coal-fired power plants, and 
researchers about the cost of these technologies. Seventeen of these 
stakeholders provided sorbent injection cost information, but these 
estimates were incomplete and not always comparable due to site-
specific variations and differing assumptions. The vendors generally 
provided lower cost estimates than those provided by the power 
industry, while estimates provided by researchers had the broadest 
range. 

EPA and DOE officials and other stakeholders identified relevant cost 
estimates compiled by other nongovernmental entities: 

* Charles River Associates, an economics and business consulting firm, 
provided cost estimates for activated carbon sorbent injection in 
combination with an existing or supplemental fabric filter.[Footnote 
32] Rather than presenting estimates of costs for particular plant 
sizes and mercury removal percentages, Charles River Associates 
provided formulas with variables for mercury removal and plant 
size.[Footnote 33] Using these formulas and a plant size of 500 
megawatts, Charles River Associates' analysis would generate estimates 
of total capital costs of about $749,278 for using sorbent injection 
with an existing fabric filter and about $20.6 million for sorbent 
injection and a supplemental fabric filter (1999 dollars). Operating 
and maintenance costs comprise a fixed cost based on plant size and a 
variable component that could be calculated for a range of mercury 
removal percentages. For example, a 90 percent mercury reduction using 
sorbent injection with an existing fabric filter for a bituminous coal-
fired 500-megawatt plant operating at 80 percent capacity over the 
course of a year (7,008 hours) would cost $999,473 per year, or about 
$0.29 per megawatt-hour. A 90 percent reduction at the same size plant 
burning subbituminous coal would cost $1.3 million per year or about 
$0.38 per megawatt-hour. Annual operating and maintenance costs were 
about $75,000 higher for the configuration where a supplemental fabric 
filter was installed. 

In its modeling, Charles River Associates considered only sorbent 
injection technology with an existing or retrofitted fabric filter 
because the firm expects that this combination would have a lower cost 
per pound of mercury removed than sorbent injection alone. Charles 
River Associates' operating and maintenance cost estimates for 
activated carbon injection alone are lower than the EPA and DOE 
estimates; however, the Charles River estimates reflect the assumption 
that plants already had a fabric filter, while EPA and DOE assumed 
plants already had an electrostatic precipitator. 

* MJ Bradley & Associates, an engineering and environmental consulting 
firm, summarized costs for other multipollutant controls that have 
undergone full-scale testing.[Footnote 34] One technology, which uses 
ozone to oxidize nitrogen oxide and mercury, has been estimated to 
remove over 90 percent of nitrogen oxide and mercury from a plant's 
flue gas; it also controls sulfur dioxide.[Footnote 35] This technology 
is estimated to cost between $90 and $120 per kilowatt in capital costs 
and $1.7 to $2.37 per megawatt-hour in annual operating and maintenance 
costs. For a 500-megawatt plant operating at 80 percent capacity, this 
would equate to $45 million to $60 million in capital costs and $6.0 
million to $8.3 million in annual operating and maintenance 
costs.[Footnote 36] MJ Bradley also estimated the costs of a system 
that removes sulfur dioxide and mercury and decomposes nitrogen oxide 
through a multi-stage oxidation, chemical, and filter process. The 
target mercury removal rate for this process is 85 to 98 percent, which 
MJ Bradley reports the manufacturer guarantees. The estimated capital 
cost of this process is between $110 and $140 per kilowatt, or $55 
million to $70 million for a 500-megawatt plant. A downstream fabric 
filter is associated with this process to remove particulate matter, 
which could add an additional cost. 

In considering the cost estimates, it is important to note that plants 
may identify and choose the most cost-effective option for complying 
with EPA's mercury rule. The cost-effectiveness of a given mercury 
control will vary by facility, depending on site-specific factors, 
including the type and configuration of controls already installed. 
Furthermore, the desired level of mercury control at a plant will 
affect its control costs and some plants may meet their mercury 
reduction goals by modifying existing air pollution control equipment, 
thereby negating the need for additional mercury controls. In cases 
where plants decide to install mercury controls, the desired control 
level will affect the cost-effectiveness of the various technologies. 
For example, sorbent injection with a downstream fabric filter may 
prove cost effective for facilities seeking a high level of reduction, 
but less cost effective for plants seeking lower level reductions 
because of the relatively high capital costs. In the example given 
above for a 70 percent mercury reduction at plants burning bituminous 
coal, based on annualized costs, EPA's estimates suggest it is more 
cost-effective for both the 100-and 975-megawatt plants to achieve that 
reduction without installing a supplemental fabric filter; however, 
DOE's estimates suggest it is more cost-effective for the 500-megawatt 
plant to install the supplemental filter when accounting for the loss 
of revenue and increased disposal costs plants could incur from not 
being able to sell their fly ash.[Footnote 37]

Fly ash disposal plays a role in determining the most cost effective 
compliance option because the plants that sell their fly ash and choose 
to use carbon-based sorbents may lose revenue and face increased 
disposal costs if they can no longer sell their fly ash.[Footnote 38] 
According to EPA, power plants sell about 35 percent of their fly ash 
for use in other applications, with 15 percent going to uses, such as 
cement manufacturing, where carbon contamination could pose a problem. 
The presence of carbon-based sorbent in fly ash may render it unusable 
for such purposes, particularly as a cement substitute in making 
concrete. Therefore, in some cases, plants using carbon-based sorbent 
may not be able to sell their fly ash and instead have to pay for its 
disposal. Plants may mitigate this problem by installing sorbent 
injection downstream of the electrostatic precipitator. This would, 
however, require the plants to install a fabric filter to collect the 
spent sorbent. DOE estimated that this configuration may be a cost-
effective method to achieve mercury reductions for plants that wish to 
continue selling their fly ash, but the high capital costs of 
installing a fabric filter may render this choice uneconomic for some 
facilities. However, based on more recent tests, EPA believes that 
chemically enhanced sorbents can be more efficient at achieving a high 
level of mercury removal and may not render fly ash unusable for other 
purposes. Therefore, the use of these sorbents might prevent a plant 
from having to install a fabric filter and allow them to continue 
selling fly ash. 

Most Stakeholders Expect the Costs to Decrease over Time: 

Regardless of the exact magnitude of costs, 22 of the 40 survey 
respondents, all of the 14 policy stakeholders we interviewed, EPA, and 
DOE expect mercury control costs to decrease over time. Stakeholders 
cited a number of reasons for this belief, including the presence of a 
mercury rule, the expected development of a market that would lead to 
competition and increased demand for technologies, and anticipated 
improvements in technology performance as a result of innovation and 
experience. According to EPA and DOE officials, the most recent test 
results of injected sorbent technologies suggest that the cost of using 
these technologies will be less than these agencies estimated in 2003, 
stemming from advances in the sorbents. Likewise, EPA's economic impact 
analysis of the mercury rule reports that the actual cost of mercury 
control may be lower than currently projected, since the rule may lead 
to further development and innovation of these technologies, which 
would likely lower their cost over time. 

In addition to the views of these stakeholders, experience with 
pollution control requirements under other air quality regulations also 
suggests that costs may decrease over time. While factors affecting the 
cost of mercury control technology may or may not be analogous to that 
of technologies to control other regulated pollutants, an examination 
of the cost trends for other air pollution controls shows that costs 
have declined over time. For example, according to EPA, the acid rain 
sulfur dioxide trading program was shown in recent estimates to cost as 
much as 83 percent less than originally projected.[Footnote 39] 
Furthermore, studies conducted by other researchers demonstrate that 
costs of air pollution control technologies have declined. For example, 
research conducted by Carnegie Mellon University found that the capital 
cost of sulfur dioxide control technology for a coal-fired power plant 
decreased from approximately $250 to $130 per kilowatt of electricity 
generating capacity between 1976 and 1995 (1997 dollars). Similarly, 
case studies analyzed by the Northeast States for Coordinated Air Use 
Management (NESCAUM) found the total operating and maintenance costs of 
sulfur dioxide controls decreased about 80 percent between 1982 and 
1997.[Footnote 40] NESCAUM also found a reduction in the capital cost 
of nitrogen oxide controls, which it attributed to improvements in 
operational efficiency. 

Concluding Observations: 

Because data on the performance of mercury controls stem from a limited 
number of tests rather than permanent installations at power plants, 
data on the long-term performance of these technologies are limited. 
Furthermore, while the available data show promising results, 
forecasting when power plants could rely on these technologies to 
achieve significant mercury reductions--such as by 2008 or later--
involves professional judgment. The judgment of the stakeholders we 
contacted varied substantially, with control vendors and some 
researchers expressing optimism about the potential for sorbent 
technologies to achieve substantial mercury reductions in the near 
term, while power industry stakeholders, DOE, and EPA highlighted the 
need for more long-term tests. Current and future DOE tests will 
enhance knowledge about these controls, especially on their 
effectiveness in removing mercury and the potential impacts they may 
have on plant operations. In addition, information from the power 
plants that plan to install mercury controls as part of settlement 
agreements or to meet state-level requirements could shed additional 
light on these issues. 

A number of factors complicate efforts to estimate the costs of 
installing mercury controls. For example, available data suggest that 
site-specific variables will dictate the level of expense that power 
plant owners and operators will incur should they install one of the 
available mercury control technologies. While even the current cost 
estimates for the most advanced of the technologies--sorbent injection-
-are highly uncertain for individual plants, many of the stakeholders 
we contacted expect these costs to decline. Further, past experience 
with other air pollution control regulations suggests that the costs of 
pollution controls decline over time due to technological improvements, 
the development of a market, and increased experience using the 
controls. 

Recent data already show a similar trend with respect to mercury 
controls. For example, EPA and DOE have stated that advanced sorbent 
technologies have the potential to achieve greater mercury removal at 
lower cost than previously estimated. Also, the emissions trading 
program established under EPA's mercury rule gives industry flexibility 
in determining how it will comply with the control targets, enabling 
plants to choose the most cost-effective compliance option, such as 
installing controls, switching fuels, or purchasing emissions 
allowances. Finally, because the power industry must also further 
reduce its emissions of nitrogen oxide and sulfur dioxide to comply 
with the interstate rule, the power industry has the opportunity to 
cost-effectively address emissions of all three pollutants 
simultaneously. 

Agency Comments: 

We provided a draft of this report to DOE and EPA for review and 
comment. DOE reviewed the report and said that it generally agreed with 
our findings. EPA's Office of Air and Radiation and Office of Research 
and Development provided technical comments, which we incorporated as 
appropriate. 

As agreed with your offices, unless you publicly announce the contents 
of this letter earlier, we plan no further distribution until 15 days 
from the report date. At that time, we will send copies of the report 
to the EPA Administrator, DOE Secretary, 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 the GAO Web site at 
[Hyperlink, http://www.gao.gov]. 

If you have any questions about this report, please contact me at (202) 
512-3841 or [Hyperlink, stephensonj@gao.gov]. Contact points for our 
Offices of Congressional Relations and Public Affairs may be found on 
the last page of this report. GAO staff who made major contributions to 
this report are listed in appendix VII. 

Signed by: 

John B. Stephenson: 
Director, Natural Resources and Environment: 

List of Requesters: 

The Honorable Olympia J. Snowe: 
Chair, Committee on Small Business and Entrepreneurship: 
United States Senate: 

The Honorable James M. Jeffords: 
Ranking Minority Member: 
Committee on Environment and Public Works: 
United States Senate: 

The Honorable Joseph I. Lieberman: 
Ranking Minority Member: 
Committee on Homeland Security and Governmental Affairs: 
United States Senate: 

The Honorable Patrick J. Leahy: 
Ranking Minority Member: 
Committee on the Judiciary: 
United States Senate: 

The Honorable Thomas R. Carper: 
Ranking Minority Member: 
Subcommittee on Clean Air, Climate Change, and Nuclear Safety: 
Committee on Environment and Public Works: 
United States Senate: 

The Honorable Barbara Boxer: 
Ranking Minority Member: 
Subcommittee on Superfund and Waste Management: 
Committee on Environment and Public Works: 
United States Senate: 

The Honorable Hillary Rodham Clinton: 
United States Senate: 

The Honorable Mark Dayton: 
United States Senate: 

The Honorable Frank Lautenberg: 
United States Senate: 

[End of section]

Appendixes: 

Appendix I: Objectives, Scope, and Methodology: 

Congressional requesters asked us to (1) describe the use, 
availability, and effectiveness of technologies to reduce mercury 
emissions at power plants; and (2) identify the factors that influence 
the cost of these technologies and report on available cost estimates. 
To respond to these objectives, we surveyed a nonprobability sample of 
59 key stakeholders in three groups, including 22 mercury control 
technology vendors, 21 representatives of the coal-fired power 
industry, and 16 individual researchers and/or government 
officials.[Footnote 41] We supplemented and corroborated, to the extent 
possible, the survey information through structured interviews with 14 
stakeholders who view the reduction of mercury emissions from a policy 
perspective, including senior staff at EPA's Office of Policy Analysis 
and Review and DOE's Office of Fossil Energy. Finally, we interviewed 
vendors and researchers of mercury emissions monitoring technology to 
obtain and analyze information on the availability and reliability of 
mercury monitoring devices. 

Our work dealt with (1) technologies or measures that are specifically 
intended to control mercury emissions and (2) modifications to existing 
controls for other pollutants (e.g., nitrogen oxides, particulate 
matter, or sulfur dioxide) that are specifically intended to enhance 
mercury removal. We did not assess the availability, use, cost, or 
effectiveness of controls for other pollutants that capture mercury as 
a side-benefit because EPA had already conducted an extensive analysis 
of that topic as part of the rule development process. As a result, our 
work addressed only technologies specifically intended to control 
mercury. We did not independently test these technologies. Lastly, we 
focused on technologies that had advanced to the field-test stage 
rather than on technologies in earlier stages of testing. Most of the 
test data we reviewed were from full-scale tests, but the field tests 
of less developed controls, such as some multipollutant controls, were 
not full-scale. In these cases, the data were obtained from slipstream 
tests at power plants, where segments, rather than the entire stream, 
of the flue gas were diverted for testing. 

We relied primarily on surveys to obtain current data and professional 
judgment on the status of mercury controls. We developed three 
different surveys, one for each stakeholder group, which requested 
information about the availability, use, effectiveness, and cost of 
mercury control technologies. The scope and nature of some questions 
varied between the three surveys in order to reflect the varying 
expertise of each stakeholder group. To the extent possible, we 
structured the questions to facilitate comparisons between the 
responses of each stakeholder group. We used this format because we 
expected researchers, government officials, and power industry 
respondents to possess broad knowledge about a portfolio of mercury 
controls while technology vendors would have extensive information 
about a limited number of controls, or those that they produce, develop 
or sell. The most significant difference between the three surveys was 
that we asked technology vendors to answer questions only about the 
control produced, developed, or sold by each vendor, whereas the 
questions for researchers, government officials, and power industry 
respondents were not limited to one mercury control. 

We developed the three surveys with survey specialists between July 
2004 and October 2004. We took steps in the design, data collection, 
and analysis phases of the work to minimize nonsampling and data 
processing errors. We conducted pretests of the surveys, and staff 
involved in the evaluation and development of mercury control 
technologies within EPA's Office of Research and Development and DOE's 
Office of Fossil Energy also reviewed and commented on the three 
surveys. We made changes to the content and format of the final surveys 
based on the pretests, comments of EPA and DOE officials, and comments 
of our internal reviewer. We followed up with those that did not 
respond promptly to our surveys. We also independently verified the 
entry of all survey responses entered into an analysis database as well 
as all formulas used in the analyses. 

We mailed paper copies of the surveys to 59 stakeholders and received 
45 surveys from 40 stakeholders (68 percent response rate), which 
included 14 representatives of coal-fired power plants, 12 researchers 
and government officials, and 14 technology vendors. Because we asked 
technology vendors to complete one survey for each mercury control 
technology that they develop, produce, or sell, the number of surveys 
exceeded the number of respondents--five of the 14 vendors responding 
to our survey submitted more than one survey. Upon receiving the 
surveys and reviewing the questions, four stakeholders (1 power 
industry representative, 1 vendor, and 2 researchers/government 
officials) informed us that they were unable to participate. Finally, 
we contacted each stakeholder who did not return a survey by the 
deadline several times, either via email, phone, or both. 

We developed separate nonprobability samples for each of the three 
groups we surveyed, identifying stakeholders based on the extent of 
their expertise and involvement with the research, development, and 
demonstration of mercury control technologies. 

* To compile a list of mercury control technology vendors, we spoke 
with DOE staff overseeing the mercury technology demonstration program 
to identify companies that either manufacture a mercury control 
technology for coal-fired power plants or research these technologies 
to develop them commercially. Although we excluded from the technology 
vendors group any company or organization that conducts research solely 
for evaluative or academic reasons and lacks a significant financial 
interest in the performance of the technology, we did include these 
stakeholders in the researcher and government official group. Next, we 
spoke with DOE and mercury technology vendors and reviewed available 
documents to identify the stage of testing of each company's 
product(s), and we included on our list the companies whose product(s) 
have undergone commercial demonstrations, full-scale field tests, pilot-
scale tests, or slipstream tests. We then corroborated the list of 
mercury control technology vendors with the Institute of Clean Air 
Companies, the national trade organization for air pollution control 
vendors, to ensure the completeness of the list of mercury control 
vendors. Our survey of mercury control technology vendors included a 
representative from each of the 22 companies we identified as meeting 
these criteria. 

* We identified an initial list of 21 representatives from the coal-
fired power industry to participate in our survey based primarily on a 
list generated from Platts' POWERdat database of the power generators 
who burned the most coal in calendar year 2002, which is the most 
recent year of available data. We determined that this database was 
sufficiently reliable for this purpose. We based our selection of 
stakeholders on the quantity of coal burned because it correlated more 
closely with mercury emissions than any other available variable. We 
included a representative from each of the 20 generators that burned 
the most coal in calendar year 2002, accounting for 60 percent of the 
coal burned for power generation in that year in the United States. One 
company from this list declined to participate in our survey. 
Therefore, we added the next-largest company on the list. This final 
group of 20 generators accounted for 59 percent of the coal burned for 
power generation in that year. Additionally, we added one company to 
our group of generators--resulting in a total of 21 generators 
surveyed--because it had begun a commercial demonstration of a mercury 
control technology. Next, we corroborated our list of generators by 
asking representatives of the following organizations to identify 
contacts within the coal-fired power industry who would be 
knowledgeable of mercury control technologies: (1) three power 
companies that have actively participated in mercury control technology 
demonstrations; (2) the Edison Electric Institute, the trade 
association for electric utilities; and (3) the National Rural Electric 
Cooperative Association, which represents utilities serving rural 
communities. The power industry stakeholders identified by these three 
organizations all corresponded with those we had placed in the group of 
21 generators. 

* For the survey targeting researchers and government officials, we 
included senior agency staff involved in the evaluation and development 
of mercury control technologies within EPA's Office of Research and 
Development and DOE's National Energy Technology Laboratory, state 
government officials in states that initiated action to limit mercury 
emissions from power plants, and experts from companies and non-profit 
organizations that do research on mercury control technologies. We 
coordinated with the State and Territorial Air Pollution Program 
Administrators/Association of Local Air Pollution Control Officials, 
the national association of state and local air pollution control 
agencies, to identify nine states that had initiated actions to reduce 
mercury emissions from power plants and the state officials that had 
been involved with research and development of mercury control 
technologies. After speaking with representatives from these states, we 
eliminated one of the states because the legislation did not 
specifically target mercury emissions. We spoke to representatives of 
the following eight states: Connecticut, Illinois, Iowa, Massachusetts, 
New Hampshire, New Jersey, North Carolina, and Wisconsin. 

We recognized that the technology vendors and power industry 
respondents might have had concerns about disclosing sensitive or 
proprietary information. Therefore, although we have included a list of 
the survey respondents below, this report does not link individual 
survey responses to any particular technology vendor or representative 
of the coal-fired power industry. We mailed the survey to stakeholders 
on October 22, 2004, and asked to receive responses by November 8, 
2004. Of the 59 stakeholders we contacted, the following 41 responded 
to our survey:[Footnote 42]

* ADA Environmental Solutions; 
* ADA Technologies Incorporated; 
* AES Corporation; 
* Alstom Power; 
* American Electric Power Company, Incorporated; 
* Andover Technologies; 
* Apogee Scientific, Incorporated; 
* Babcock Power Incorporated; 
* Basin Electric Power Cooperative; 
* CarboChem; 
* Cormetech, Incorporated; 
* Dominion Resources, Incorporated; 
* Electric Power Research Institute; 
* Enerfab Clean Air Technologies (CR Clean Air Technologies); 
* FirstEnergy Corporation; 
* EnviroScrub Technologies Corporation; 
* Hamon Research Cottrell; 
* Illinois Environmental Protection Agency, Bureau of Air; 
* KFx; 
* Mobotec USA; 
* NORIT-Americas, Incorporated; 
* New Hampshire Department of Environmental Sciences; 
* New Jersey Department of Environmental Protection; 
* North Carolina Division of Air Quality; 
* Powerspan; 
* PPL Corporation; 
* Progress Energy, Incorporated; 
* Reaction Engineering; 
* Reliant Energy Incorporated; 
* Scottish Power Plc (Known as Pacificorps in the U.S.); 
* Sorbent Technologies Corporation; 
* Southern Company; 
* Southern Research Institute; 
* TXU Corporation; 
* Tennessee Valley Authority; 
* United Technologies; 
* U.S. Department of Energy, National Energy Technology Laboratory; 
* U.S. EPA, Office of Research and Development, Air Pollution 
Prevention and Control Division; 
* We Energies; 
* Wisconsin Department of Natural Resources, Bureau of Air Management; 
* Xcel Energy, Incorporated: 

We supplemented and corroborated, to the extent possible, the survey 
information with testimonial evidence. This included structured 
interviews with 14 policy stakeholders familiar with the policy 
implications of mercury control technology research, including senior 
staff at EPA's Office of Policy Analysis and Review and DOE's Office of 
Fossil Energy, state and local regulatory organizations, electric 
utility associations, and environmental organizations.[Footnote 43] We 
developed a nonprobability sample for the group of policy stakeholders. 
We worked with a survey expert to develop a set of structured interview 
questions about the availability, use, effectiveness, and cost of 
mercury control technologies. In order to minimize nonsampling error, 
we took steps to ensure that the questions were unambiguous, balanced, 
and clearly understandable. The interview questions were similar to the 
survey questions, but tailored to reflect the policy expertise of the 
interview participants. For example, rather than asking interview 
participants to provide data on mercury technology demonstrations, we 
sought their views on the implications of mercury technology 
demonstrations for mercury policies. We conducted pretests of the 
structured interview, including one with an EPA official in the Office 
of Policy Analysis and Review. We made changes to the content and 
format of the final interview questions based on the pretests. 

We conducted the 14 structured interviews between November 2004 and 
December 2004 with stakeholders from the following 13 
organizations:[Footnote 44]

* American Public Power Association; 
* Clean Air Task Force; 
* Edison Electric Institute; 
* Institute of Clean Air Companies; 
* MJ Bradley; 
* National Rural Electric Cooperative Association; 
* National Wildlife Federation; 
* Northeast States for Coordinated Air Use Management; 
* Regional Air Pollution Control Agency; 
* State and Territorial Air Pollution Program 
Administrators/Association of Local Air Pollution Control Officers; 
* U.S. Department of Energy, Office of Fossil Energy; 
* U.S. Environmental Protection Agency, Office of Air and Radiation, 
Office of Policy Analysis and Review; 
* U.S. Environmental Protection Agency, Office of Air and Radiation, 
Office of Air Quality Planning and Standards: 

Finally, because of the important role monitoring data play in the 
regulation of air pollutants, we gathered and analyzed information on 
the availability and reliability of two kinds of mercury monitoring 
devices--sorbent traps and continuous emissions monitors--by conducting 
seven structured interviews with the technology vendors and researchers 
in the government and private sectors. We developed the list by 
consulting with EPA's lead expert on mercury monitoring technology and 
then comparing it to the list of presenters at DOE's Mercury 
Measurements Workshop, which was conducted in July 2004. Because this 
list of monitoring technology vendors primarily represented one of the 
two advanced mercury monitors, we included an organization regarded as 
a major developer of the other mercury monitoring device. Finally, we 
also included researchers and government stakeholders with broad 
knowledge of the mercury monitoring industry. 

We could not interview all 18 stakeholders we identified for the 
sorbent trap and continuous emissions monitors because of time 
constraints. Therefore, we decided to (1) interview four researchers 
and government officials, (2) interview the major producer of sorbent 
traps, and (3) interview a random sample of the multiple vendors 
involved with the eight kinds of continuous emissions monitors. Within 
this last group, we compiled a list of 13 mercury monitoring vendors, 
which was then randomized by a senior GAO methodologist. We interviewed 
the first 3 stakeholders on the randomized list of 13 mercury 
monitoring vendors in order to include their knowledge and perspectives 
on the industry. We were not able to reach the sorbent trap producer 
for an interview. 

We based the questions for the monitoring interviews on those posed in 
the mercury control technology surveys, including the same concepts and 
emphasizing the availability and level of demonstration of monitoring 
technologies, and again took steps to minimize nonsampling errors. We 
conducted two pretests of the monitoring interviews. Finally, we 
corroborated the numerical values used in questions about the accuracy 
and reliability of mercury monitors with EPA's mercury monitoring 
expert in the Office of Research and Development. We made changes to 
the content and format of the final interview questions based on the 
pretests and the EPA official's comments. 

Lastly, we identified and reviewed governmental and nongovernmental 
reports estimating the cost of mercury control technologies. We 
identified two government cost reports--one from EPA and one from DOE-
-and four nongovernmental cost reports. We excluded two of the 
nongovernmental reports from our analysis because these reports 
addressed cost issues that were either too limited in scope or were not 
germane to our research objectives. We then reviewed the results of 
both government reports and two remaining nongovernmental reports as 
part of our technology cost analysis. We took several steps to assess 
the validity and reliability of computer data underlying the cost 
estimates in the EPA, DOE, and nongovernmental reports which were 
discussed in our findings, including reviewing the documentation and 
assumptions underlying EPA's economic model and assessing the agency's 
process for ensuring that the model data are sufficient, competent, and 
relevant. We determined that these four reports are sufficiently 
reliable for the purposes of this report. 

As part of our effort to consider data on mercury control 
demonstrations and costs, we assessed compliance with internal controls 
related to the availability of timely, relevant, and reliable 
information. We also obtained data on mercury emissions. Because the 
emissions data are used for background purposes only, we did not assess 
their reliability. 

We performed our work between May 2004 and May 2005 in accordance with 
generally accepted government auditing standards. 

[End of section]

Appendix II: Availability and Costs of Mercury Monitoring Technology: 

This appendix provides information on technologies that facilities may 
use to monitor mercury emissions, including background information on 
monitoring technologies and requirements under EPA's mercury rule, as 
well as on the availability and cost of different monitoring 
technologies. 

Background: 

In addition to technologies that control emissions, those that monitor 
the amount of a pollutant emitted can play an equally important role in 
the success of an air quality rule's implementation. For example, 
effective emissions monitoring assists facilities and regulators in 
assuring compliance with regulations. In some cases, monitoring data 
can also help facilities better understand the efficiency of their 
processes and identify ways to optimize their operations. 

Accurate emissions monitoring is particularly important for trading 
programs, such as that established by the mercury rule. According to 
EPA, the most widespread existing requirements for using advanced 
monitoring technologies stem from EPA's Acid Rain program. Under the 
program, power plants have been allowed to buy and sell emissions 
allowances, but each facility must hold an allowance for each ton of 
sulfur dioxide it emitted in a given year; furthermore, facilities must 
continuously monitor their emissions.[Footnote 45] According to EPA, 
monitoring ensures that each allowance actually represents the 
appropriate amount of emissions, and that allowances generated by 
various sources are equivalent, instilling confidence in the program. 
Conversely, a study by the National Academy of Public Administration 
found that the lack of monitoring in other trading programs led to 
difficulty in ensuring the certainty of emissions reductions. 

EPA's mercury rule requires mercury emissions monitoring and quarterly 
reporting of mercury emissions data. For plants that emit at least 29 
pounds of mercury annually, EPA requires continuous emissions 
monitoring, while sources that emit less than this amount may instead 
conduct periodic testing--testing their emissions once or twice a year 
depending on their emissions level. According to EPA, the mercury 
emissions from sources exempt from continuous monitoring comprise 
approximately 5 percent of nationwide emissions. EPA estimates that the 
annual impact in monitoring costs for the entire industry will total 
$76.4 million.[Footnote 46]

EPA Expects That Monitoring Technologies Will Be Available Prior to the 
Compliance Deadlines: 

EPA expects that two technologies will be available to monitor mercury 
emissions continuously prior to the rule's deadline and requires 
continuous emissions monitoring for most facilities either by a 
Continuous Emissions Monitoring System (CEMS) or a sorbent trap 
monitoring system, while facilities that emit low levels of mercury can 
conduct periodic monitoring using a testing protocol known as the 
Ontario-Hydro Method: 

* CEMS continuously measures pollutants released by a source, such as a 
coal-fired power plant. Some CEMSs extract a gas sample from a 
facility's exhaust and transport it to a separate analyzer while others 
allow effluent gas to enter a measurement cell inserted into a stack or 
duct. This allows for continuous, real-time emissions monitoring. EPA 
estimates that a unit's annual CEMS operating, testing, and maintenance 
cost would be about $87,000, while a unit's capital cost would be about 
$70,000. 

* Sorbent trap monitoring systems collect a mercury sample by passing 
flue gas through a mercury trapping medium, such as an activated carbon 
tube. This sample is periodically removed and sent to a lab for 
analysis. The rule requires that the average measurement of two 
separate sorbent trap readings be reported. Sorbent trap monitoring 
allows for continuous monitoring, but is not considered a real-time 
method. EPA estimates that a unit's annual sorbent trap operating and 
testing costs would be about $113,000 per year, while a unit's capital 
cost would be about $20,000. 

* The Ontario-Hydro Method, a periodic testing method, involves 
manually extracting a sample of flue gas from a coal-fired plant's 
stack or duct, usually over a period of a few hours, which is then 
analyzed in a laboratory. EPA estimates this method would cost about 
$12,500 a year for two tests and about $7,000 for one test. 

Stakeholders Believe That Mercury Monitoring Technology Is Available, 
Reliable, and Will be Able to Meet Quality Control and Assurance 
Standards by 2008: 

All of the stakeholders we asked about the availability of CEMS or 
sorbent trap systems said that the technologies were available for 
purchase. Furthermore, an EPA monitoring technology expert and the 
vendors we interviewed agreed that there were no technical or 
manufacturing challenges that would prevent vendors from supplying 
monitors to coal-fired power plants by 2008. However, some researchers 
identified factors that could affect vendors' ability to supply 
monitors by that date, including whether vendors had sufficient 
production capacity to meet the industry's demand for the equipment. 
All three vendors we interviewed were aware of power plants in other 
countries that had installed mercury monitoring equipment (including 
Germany, Japan, and the United Kingdom). Two respondents were aware of 
power plants in the United States that had permanently installed 
mercury monitoring equipment. 

Most researchers considered CEMS and sorbent trap technologies to be 
accurate and reliable, and the CEMS vendors also characterized their 
technologies as accurate and reliable. Researchers cited the need for 
additional testing of certain subcomponents of the continuous 
monitoring systems. Stakeholders were generally confident that these 
technologies would be able to meet proposed quality control and 
assurance standards by 2008, although two researchers expressed 
concerns that EPA's proposed standards might be too strict for CEMS to 
meet. 

According to EPA, recent field tests have demonstrated that sorbent 
trap systems can be as accurate as CEMS. The rule requires the 
implementation of quality assurance procedures for sorbent trap 
monitoring systems, which EPA says are based on field research and 
input from parties that commented on the agency's mercury rule during 
the public comment period. EPA acknowledges that there may be problems 
with the technology, such as the possibility of the traps becoming 
compromised, lost, or broken during transit or analysis, which could 
result in missing data; however, EPA also believes steps can be taken 
to minimize these possibilities. 

[End of section]

Appendix III: Summary of Field-Scale Tests of Mercury Controls: 

The table below summarizes data about mercury control tests, including 
the power plant location, duration of continuous testing, coal type, 
and average mercury removal. We obtained data from DOE's National 
Energy Technology Laboratory and from the 40 survey respondents about 
field tests. The tests that have been partially funded by DOE's 
National Energy Technology Laboratory are identified in the table below 
by an asterisk symbol. 

Table 1: Summary of Mercury Control Field Test Data: 

Mercury control category: Sorbent; 
Technology: Activated carbon*; 
Location: Wilsonville, AL; 
Duration: 9 days; 
Test year: 2001; 
Coal type: Bituminous; 
Average mercury reduction[A]: Various test results reported to GAO: 78-
90 percent. 

Mercury control category: Sorbent; 
Technology: Activated carbon*; 
Location: Pleasant Prairie, WI; 
Duration: Three 5-day tests; 
Test year: 2001; 
Coal type: Subbituminous; 
Average mercury reduction[A]: 46-73 percent. 

Mercury control category: Sorbent; 
Technology: Activated carbon*; 
Location: Somerset, MA; 
Duration: 10 days; 
Test year: 2002; 
Coal type: Bituminous; 
Average mercury reduction[A]: Various test results reported to GAO: 85 
to 90 percent. 

Mercury control category: Sorbent; 
Technology: Activated carbon*; 
Location: Salem, MA; 
Duration: 4 days; 
Test year: 2002; 
Coal type: Bituminous; 
Average mercury reduction[A]: 85-95 percent[B]. 

Mercury control category: Sorbent; 
Technology: Activated carbon; 
Location: Underwood, ND; 
Duration: 5 days; 
Test year: 2003; 
Coal type: Lignite; 
Average mercury reduction[A]: 70 percent. 

Mercury control category: Sorbent; 
Technology: Activated carbon; 
Location: Denver, CO; 
Duration: 6 days[C]; 
Test year: 2004; 
Coal type: Subbituminous; 
Average mercury reduction[A]: 64 percent. 

Mercury control category: Sorbent; 
Technology: Activated carbon; 
Location: Denver, CO; 
Duration: 3 hours; 
Test year: 2004; 
Coal type: Subbituminous; 
Average mercury reduction[A]: 86 percent. 

Mercury control category: Sorbent; 
Technology: Activated carbon; 
Location: Undisclosed; 
Duration: 1 day; 
Test year: 2004; 
Coal type: Subbituminous; 
Average mercury reduction[A]: 30 percent. 

Mercury control category: Sorbent; 
Technology: Activated carbon; 
Location: Undisclosed; 
Duration: 2 days; 
Test year: 2004; 
Coal type: Subbituminous; 
Average mercury reduction[A]: 55 percent. 

Mercury control category: Sorbent; 
Technology: Activated carbon and sorbent enhancement*; 
Location: Stanton, ND; 
Duration: 1 month; 
Test year: 2004; 
Coal type: Lignite; 
Average mercury reduction[A]: 63 percent. 

Mercury control category: Sorbent; 
Technology: Activated carbon*; 
Location: Newnan, GA; 
Duration: 1 month; 
Test year: 2004; 
Coal type: Bituminous; 
Average mercury reduction[A]: According to preliminary analysis, 
removal varied by measurement point within the process: ESP[D] +ACI, 
removal ranged from a minimum of 50 to a maximum of 91 percent 
(majority data 60-85 percent); ESP+ACI+scrubber, removal ranged from a 
minimum of 50 to a maximum of 97 percent (majority data 70-94 percent). 

Mercury control category: Sorbent; 
Technology: Activated carbon*; 
Location: Newnan, GA; 
Duration: Not available: testing ongoing[E]; 
Test year: 2004-2005; 
Coal type: Bituminous; 
Average mercury reduction[A]: Not available: testing ongoing[E]. 

Mercury control category: Sorbent; 
Technology: Activated carbon and sorbent enhancement*; 
Location: Beulah, ND; 
Duration: 2 months; 
Test year: 2005; 
Coal type: Lignite; 
Average mercury reduction[A]: Not available: testing ongoing[E]. 

Mercury control category: Sorbent; 
Technology: Activated carbon*[F]; 
Location: Monroe, MI; 
Duration: Not yet tested[E]; 
Test year: 2005; 
Coal type: Blend: Subbituminous/Bituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Sorbent; 
Technology: Activated carbon*[F]; 
Location: Conesville, OH; 
Duration: Not yet tested[E]; 
Test year: 2005; 
Coal type: Bituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon; 
Location: Cliffside, NC; 
Duration: Several multi-hour tests over 1-week period; 
Test year: 2003; 
Coal type: Bituminous; 
Average mercury reduction[A]: Average varied; mercury removal ranged 
from a minimum of 20 percent to a maximum of 90 percent. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon; 
Location: Athens, OH; 
Duration: Several multi-hour tests over 2-week period; 
Test year: 2003; 
Coal type: Bituminous; 
Average mercury reduction[A]: 70 percent. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: St. Louis, MO; 
Duration: 30 days; 
Test year: 2004; 
Coal type: Subbituminous; 
Average mercury reduction[A]: 90 percent. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: Near Garden City, KS; 
Duration: 30 days; 
Test year: 2004; 
Coal type: Subbituminous; 
Average mercury reduction[A]: 90 percent. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: East China Township, MI; 
Duration: 30 days; 
Test year: 2004; 
Coal type: Blend: Bituminous/Subbituminous; 
Average mercury reduction[A]: 94 percent. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon; 
Location: Undisclosed; 
Duration: Greater than 10 days; 
Test year: 2004; 
Coal type: Lignite; 
Average mercury reduction[A]: 70 percent. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon; 
Location: Undisclosed; 
Duration: 1 day; 
Test year: 2004; 
Coal type: Subbituminous; 
Average mercury reduction[A]: 60 percent. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: Stanton, ND; 
Duration: 24 days; 
Test year: 2004; 
Coal type: Lignite; 
Average mercury reduction[A]: 70 percent. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: Stanton, ND; 
Duration: 1 month; 
Test year: 2004; 
Coal type: Lignite; 
Average mercury reduction[A]: Not yet available[E]. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: Spencer, NC; 
Duration: 3 months; 
Test year: 2005; 
Coal type: Bituminous; 
Average mercury reduction[A]: Not yet available[E]. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: Stanton, ND; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Lignite; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: Portland, PA; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Bituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: Located near Goldsboro, NC; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Bituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: Romeoville, IL (tentative location); 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Subbituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: Glenrock, WY; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Subbituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: Chicago, IL; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Subbituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: Muscatine, IA; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Subbituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Sorbent; 
Technology: Chemically enhanced carbon*; 
Location: Council Bluffs, IA; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Subbituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Sorbent; 
Technology: Non-Carbon; 
Location: Denver, CO; 
Duration: 6 hours; 
Test year: 2004; 
Coal type: Subbituminous; 
Average mercury reduction[A]: 28 percent. 

Mercury control category: Sorbent; 
Technology: Non-Carbon; 
Location: Denver, CO; 
Duration: 6-7 days[H]; 
Test year: 2004; 
Coal type: Subbituminous; 
Average mercury reduction[A]: Various test results reported to GAO: 51 
percent reported for 7-day test; 57-68 percent reported for 6-day test. 

Mercury control category: Sorbent; 
Technology: Non-Carbon*; 
Location: North Bend, OH; 
Duration: 1 month; 
Test year: 2005; 
Coal type: Bituminous; 
Average mercury reduction[A]: Not yet available[E]. 

Mercury control category: Multipollutant; 
Technology: Activated carbon and enhanced particulate collection*[I]; 
Location: Wilsonville, AL; 
Duration: 5 months; 
Test year: 2003; 
Coal type: Bituminous; 
Average mercury reduction[A]: 86 percent. 

Mercury control category: Multipollutant; 
Technology: Activated carbon and enhanced particulate collection*[I]; 
Location: Cheshire, OH; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Bituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Multipollutant; 
Technology: Activated carbon and enhanced particulate collection*[I]; 
Location: Newark, AR; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Subbituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Multipollutant; 
Technology: Activated carbon and enhanced particulate collection*[I]; 
Location: Near Fairfield, TX; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Lignite or Lignite/Subbituminous blend; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Multipollutant; 
Technology: Sorbent and high velocity air; 
Location: Moncure, NC; 
Duration: 14 days; 
Test year: 2002; 
Coal type: Bituminous; 
Average mercury reduction[A]: 80 percent. 

Mercury control category: Multipollutant; 
Technology: Wet ESP; 
Location: Shippingport, PA; 
Duration: Not specified; 
Test year: 2001-2003; 
Coal type: Subbituminous; 
Average mercury reduction[A]: 78 percent. 

Mercury control category: Multipollutant; 
Technology: Corona Discharge[J]; 
Location: Shadyside, OH; 
Duration: 6 days; 
Test year: 2004; 
Coal type: Blend: Bituminous and subbituminous; 
Average mercury reduction[A]: 75 percent. 

Mercury control category: Mercury oxidation; 
Technology: Chlorine-based additives*; 
Location: Located near Center, ND; 
Duration: 2 months expected; 
Test year: 2005; 
Coal type: Lignite; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Mercury oxidation; 
Technology: Chlorine-based additives*; 
Location: Mt. Pleasant, TX; 
Duration: 1 month expected[E]; 
Test year: 2005; 
Coal type: Lignite; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Enhancement; 
Technology: Wet FGD[K] Additive*; 
Location: Moscow, OH; 
Duration: 2 weeks; 
Test year: 2001; 
Coal type: Bituminous; 
Average mercury reduction[A]: 52 percent. 

Mercury control category: Enhancement; 
Technology: Wet FGD Additive*; 
Location: Litchfield, MI; 
Duration: 4 months; 
Test year: 2001; 
Coal type: Bituminous; 
Average mercury reduction[A]: 79 percent. 

Mercury control category: Enhancement; 
Technology: Wet FGD Additive; 
Location: Mt. Storm Lake, northeastern WV; 
Duration: 3 days; 
Test year: 2004; 
Coal type: Bituminous; 
Average mercury reduction[A]: 71 percent. 

Mercury control category: Enhancement; 
Technology: Wet FGD Additive; 
Location: Mt. Storm Lake, northeastern WV; 
Duration: 7 days; 
Test year: 2004; 
Coal type: Bituminous; 
Average mercury reduction[A]: Over 90 percent. 

Mercury control category: Enhancement; 
Technology: Wet FGD Additive*; 
Location: Newnan, GA; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Bituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Enhancement; 
Technology: Wet FGD Additive*; 
Location: Conesville, OH; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Bituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Enhancement; 
Technology: Wet FGD Additive*; 
Location: Mt. Pleasant, TX; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Lignite; 
Average mercury reduction[A]: Not yet tested[E]. 

Mercury control category: Other; 
Technology: Fixed sorbent structure*; 
Location: Stanton, ND; 
Duration: 6 months expected; 
Test year: 2004-2005; 
Coal type: Lignite, then switched to subbituminous during testing; 
Average mercury reduction[A]: Not available: testing ongoing[E]. 

Mercury control category: Other; 
Technology: Fixed sorbent structure*; 
Location: Newnan, GA; 
Duration: 5 months expected; 
Test year: 2005; 
Coal type: Bituminous; 
Average mercury reduction[A]: Not yet available[E]. 

Mercury control category: Other; 
Technology: Combustion modification*; 
Location: Rogersvile, TN; 
Duration: TBD[G]; 
Test year: TBD[G]; 
Coal type: Bituminous; 
Average mercury reduction[A]: Not yet tested[E]. 

Source: DOE National Energy Technology Laboratory and GAO analysis of 
survey responses. 

* Field tests partially funded by DOE's National Energy Technology 
Laboratory. 

[A] Average mercury removal reflects the total mercury removal achieved 
by the entire system of pollution controls, not just the mercury 
control, installed at the power plant. 

[B] Measurements obtained over a four-day test showed overall mercury 
capture of 85 to 95 percent. 

[C] The test was conducted for 3 to 8 hours per day. 

[D] ESP is the abbreviation for electrostatic precipitator. 

[E] This is based on DOE's information as of February 2005. 

[F] The research team has not yet finalized the selection of sorbent 
for this test. The research team is testing activated carbon, but will 
also consider using chemically enhanced carbon injection at this site. 

[G] TBD means to be determined. DOE's National Energy Technology 
Laboratory had awarded funding for this project but a specific testing 
timeframe had not been identified yet as of February 2005. 

[H] The test was conducted for 3 to 8 hours per day. Survey respondents 
reported test durations of 6 days and 7 days. 

[I] This combination of pollution controls includes an enhanced, 
compact fabric filter designed to capture mercury and particulates at 
plants already using an electrostatic precipitator. 

[J] EPA describes corona discharge technology as the "generation of an 
intense corona discharge (ionization of air by a high voltage 
electrical discharge)" in the flue gas (page 7-43). The corona 
discharge triggers a series of chemical reactions that are intended to 
improve the capture of mercury and particulate matter. US EPA, National 
Risk Management Research Laboratory, Control of Mercury Emissions from 
Coal-Fired Electric Utility Boilers: Interim Report Including Errata 
Dated March 21, 2002 (Research Triangle Park, NC, 2002). 

[K] FGD is the abbreviation for flue gas desulfurization. 

[End of table]

[End of section]

Appendix IV: Summary of Stakeholder Perceptions about Availability of 
Mercury Controls: 

This appendix provides more detailed information on stakeholders' views 
regarding the availability of the different mercury controls. Please 
refer back to appendix I for details about our survey methodology. 

Of the stakeholders that either responded to our survey (40) or 
participated in an interview (14), a majority (40) believed that at 
least one technology was currently available for purchase. As shown in 
table 2, many of the researchers and government officials said that 
activated carbon injection (8 of 12) and chemically enhanced carbon (7 
of 12) are currently available, while less than half of the power 
industry officials also believe activated carbon injection technology 
is available (6 of 14). All of the vendors associated with carbon-based 
sorbent injection, including activated carbon (4) and chemically 
enhanced carbon (2), described their technology as available. In 
addition, 13 of the 14 policy stakeholders we interviewed--those who do 
not participate in technology research but are involved in the 
development of mercury control policy, including representatives of 
EPA, DOE, regional and local air pollution agencies, environmental 
advocacy groups, and the electric utility industry--believe that 
sorbent technology is currently available for purchase. 

Table 2: Stakeholder Perceptions on Availability of Sorbent 
Technologies[A]: 

Technology: Activated carbon injection (ACI): 

Stakeholder group: Coal-fired power industry; 
Available: 6; 
Not available: 3; 
Do not know: 3; 
Did not answer: 2; 
Total: 14. 

Stakeholder group: Researchers and government officials; 
Available: 8; 
Not available: 1; 
Do not know: 1; 
Did not answer: 2; 
Total: 12. 

Stakeholder group: Technology vendors[B]; 
Available: 4; 
Not available: 0; 
Do not know: 0; 
Did not answer: 0; 
Total: 4. 

Stakeholder group: Policy stakeholders; 
Available: 13; 
Not available: 1; 
Do not know: 0; 
Did not answer: 0; 
Total: 14. 

Total responses; 
Available: 31; 
Not available: 5; 
Do not know: 4; 
Did not answer: 4; 
Total: 44[B]. 

Technology: Chemically enhanced ACI: 
 
Stakeholder group: Coal-fired power industry; 
Available: 3; 
Not available: 5; 
Do not know: 4; 
Did not answer: 2; 
Total: 14. 

Stakeholder group: Researchers and government officials; 
Available: 7; 
Not available: 1; 
Do not know: 1; 
Did not answer: 3; 
Total: 12. 

Stakeholder group: Technology vendors[B]; 
Available: 2; 
Not available: 0; 
Do not know: 0; 
Did not answer: 0; 
Total: 2. 

Stakeholder group: Policy stakeholders; 
Available: 11; 
Not available: 1; 
Do not know: 2; 
Did not answer: 0; 
Total: 14. 

Total responses; 
Available: 23; 
Not available: 7; 
Do not know: 7; 
Did not answer: 5; 
Total: 42[B]. 

Technology: Non-carbon sorbent: 

Stakeholder group: Coal-fired power industry; 
Available: 0; 
Not available: 8; 
Do not know: 4; 
Did not answer: 2; 
Total: 14. 

Stakeholder group: Researchers and government officials; 
Available: 1; 
Not available: 2; 
Do not know: 5; 
Did not answer: 4; 
Total: 12. 

Stakeholder group: Technology vendors[B]; 
Available: 1; 
Not available: 1; 
Do not know: 0; 
Did not answer: 0; 
Total: 2. 

Stakeholder group: Policy stakeholders; 
Available: 4; 
Not available: 4; 
Do not know: 6; 
Did not answer: 0; 
Total: 14. 

Total responses; 
Available: 6; 
Not available: 15; 
Do not know: 15; 
Did not answer: 6; 
Total: 42[B]. 

Source: GAO. 

[A] Given the uncertainty about federal mercury reduction goals that 
existed prior to the March 2005 mercury rule and the fact that field 
testing of mercury controls is ongoing, some of the stakeholders were 
reluctant to make conclusions about the availability of all mercury 
controls when we asked them in November and December 2004. Therefore, 
some participants did not answer this question, and the number of 
responses for each mercury control reflects in part the extent of field 
testing. 

[B] The number of responses for the question on availability does not 
correspond to the overall number of survey responses because the 
availability question differed slightly for technology vendors. We did 
not seek the technology vendors' perceptions of all mercury controls, 
an option we gave the other stakeholders, but asked the vendors whether 
the mercury control they produce, develop, and/or sell is available for 
purchase without regard to technology effectiveness. 

[End of table]

The survey responses regarding the availability of other mercury 
controls were more limited and less optimistic than those for sorbent 
injection. While 40 of the 54 stakeholders answered questions about the 
availability of activated carbon injection, far fewer respondents 
answered the questions about the availability of other 
controls.[Footnote 47] As shown in table 3, the stakeholders who 
responded to questions about nonsorbent control technologies, such as 
multipollutant controls, mercury oxidation technologies, and 
enhancements to existing controls for other pollutants, were more mixed 
in their views about the availability of these technologies. For 
example, researchers and government officials expressed a range of 
views about mercury oxidation technologies--4 believe they are 
available, 3 do not think they are available, 2 did not know, and 3 
chose not to answer this question. 

Table 3: Stakeholder Perceptions on Availability of Non-Sorbent Mercury 
Controls[A]: 

Technology: Mercury oxidation technologies: 

Stakeholder group: Coal-fired power industry; 
Available: 0; 
Not available: 8; 
Do not know: 4; 
Did not answer: 2; 
Total: 14. 

Stakeholder group: Researchers and government officials; 
Available: 4; 
Not available: 3; 
Do not know: 2; 
Did not answer: 3; 
Total: 12. 

Stakeholder group: Technology vendors[B]; 
Available: 1; 
Not available: 1; 
Do not know: 0; 
Did not answer: 0; 
Total: 2. 

Stakeholder group: Policy stakeholders; 
Available: 5; 
Not available: 6; 
Do not know: 3; 
Did not answer: 0; 
Total: 14. 

Total responses; 
Available: 10; 
Not available: 18; 
Do not know: 9; 
Did not answer: 5; 
Total: 42[B]. 

Technology: Multipollutant controls: 

Stakeholder group: Coal-fired power industry[C]; 
Available: 4; 
Not available: 3; 
Do not know: 0; 
Did not answer: 9; 
Total: 16. 

Stakeholder group: Researchers and government officials[C]; 
Available: 6; 
Not available: 2; 
Do not know: 0; 
Did not answer: 6; 
Total: 14. 

Stakeholder group: Technology vendors[B,C]; 
Available: 4; 
Not available: 4; 
Do not know: 0; 
Did not answer: 0; 
Total: 8. 

Stakeholder group: Policy stakeholders[C]; 
Available: 12; 
Not available: 4; 
Do not know: 2; 
Did not answer: 3; 
Total: 21. 

Total responses; 
Available: 26; 
Not available: 13; 
Do not know: 2; 
Did not answer: 18; 
Total: 59[B,C]. 

Technology: Enhancements to existing controls: 

Stakeholder group: Coal-fired power industry[D]; 
Available: 0; 
Not available: 2; 
Do not know: 1; 
Did not answer: 12; 
Total: 15. 

Stakeholder group: Researchers and government officials[D]; 
Available: 5; 
Not available: 4; 
Do not know: 0; 
Did not answer: 6; 
Total: 15. 

Stakeholder group: Technology vendors[B,D]; 
Available: 1; 
Not available: 0; 
Do not know: 0; 
Did not answer: 0; 
Total: 1. 

Stakeholder group: Policy stakeholders[D]; 
Available: 18; 
Not available: 1; 
Do not know: 0; 
Did not answer: 5; 
Total: 24. 

Total responses; 
Available: 24; 
Not available: 7; 
Do not know: 1; 
Did not answer: 23; 
Total: 55[B,D]. 

Source: GAO. 

[A] Given the uncertainty about federal mercury reduction goals that 
existed prior to the March 2005 mercury rule and the fact that field 
testing of mercury controls is ongoing, some of the stakeholders were 
reluctant to make conclusions about the availability of all mercury 
controls when we asked them in November and December 2004. Therefore, 
some participants did not answer this question, and the number of 
responses for each mercury control reflects in part the extent of field 
testing. 

[B] The number of responses for the question on availability does not 
correspond to the overall number of survey responses because the 
availability question differed slightly for technology vendors. We did 
not seek the technology vendors' perceptions of all mercury controls, 
an option we gave the other stakeholders, but asked the vendors whether 
the mercury control they produce, develop, and/or sell is available for 
purchase without regard to technology effectiveness. 

[C] The number of responses for the question on availability for 
multipollutants controls does not correspond to the overall number of 
survey responses because some stakeholders identified more than one 
multipollutant control and provided different responses about the 
availability of those controls. 

[D] The number of responses for the question on availability for 
enhancements to existing controls does not correspond to the overall 
number of survey responses because some stakeholders identified more 
than one enhancement and provided different responses about the 
availability of those enhancements. 

[End of table]

Finally, the 14 policy stakeholders we interviewed also expressed mixed 
views on the availability of mercury controls. Nine described various 
multipollutant controls as available, 5 viewed mercury oxidation as 
available, and 8 regarded various enhancements to existing technologies 
as available. 

[End of section]

Appendix V: Stakeholder Confidence in Ability of Technologies to 
Achieve Mercury Reductions under Three Scenarios: 

This appendix summarizes the perceptions of survey respondents in the 
ability of mercury controls to reduce emissions under three scenarios. 
(Appendix I provides details about our survey methodology.)

We asked survey respondents to assess their confidence in the ability 
of power plants to achieve mercury reductions of 50, 70, and 90 percent 
by the year 2008 under two different scenarios. The first scenario 
resembled the cap-and-trade approach recently finalized by EPA in that 
it asked stakeholders to consider whether the industry could use 
available technologies to achieve industrywide reductions of 50, 70 or 
90 percent by 2008. The second scenario was similar to an alternative 
approach considered by EPA that would have required each plant to 
reduce emissions; for this scenario we asked respondents whether each 
individual plant could use available technologies to achieve the 
percentage reductions by 2008.[Footnote 48]

As shown in tables 4 through 9, the confidence levels depended on the 
level of reduction required and by stakeholder group. Overall, the 
technology vendors answering this question expressed the greatest 
confidence, while the power industry respondents were the least 
confident. Within each stakeholder group, respondents expressed the 
greatest confidence overall in achieving a 50 percent reduction by 
2008--a reduction that EPA requires under its 2010 cap--and 
progressively less confidence in the 70 and 90 percent scenarios. For 
both possible control scenarios--the national limit and facility-
specific reductions--a majority of the 38 respondents[Footnote 49] 
expressed confidence in achieving the 50 percent reductions (see tables 
4 and 5), but many lacked confidence in the feasibility of 90 percent 
mercury reductions by 2008 (see tables 8 and 9). Respondents expressed 
mixed opinions about the feasibility of 70 percent reductions by 2008, 
as shown in tables 6 and 7. 

Table 4: Stakeholder Confidence in Reducing Nationwide Mercury 
Emissions 50 Percent by 2008: 

Scale of mercury reduction: 50 percent reduction nationwide[A]; 
Confidence level: Very confident or confident; 
Stakeholder group: Power industry respondents: 2; 
Stakeholder group: Researchers/government officials: 9; 
Stakeholder group: Vendors: 12; 
Total: 23. 

Confidence level: Less confident; 
Stakeholder group: Power industry respondents: 5; 
Stakeholder group: Researchers/government officials: 1; 
Stakeholder group: Vendors: 1; 
Total: 7. 

Confidence level: Not at all confident; 
Stakeholder group: Power industry respondents: 6; 
Stakeholder group: Researchers/government officials: 0; 
Stakeholder group: Vendors: 0; 
Total: 6. 

Confidence level: Do not know; 
Stakeholder group: Power industry respondents: 1; 
Stakeholder group: Researchers/government officials: 1; 
Stakeholder group: Vendors: 0; 
Total: 2. 

Scale of mercury reduction: Total respondents; 
Stakeholder group: Power industry respondents: 14; 
Stakeholder group: Researchers/government officials: 11[B]; 
Stakeholder group: Vendors: 13[B]; 38. 

Source: GAO. 

[A] The survey asked stakeholders how confident they were that power 
plants could reduce mercury emissions 50 percent by 2008. In this case, 
respondents were asked to consider reductions averaged across power 
plants in the United States, which does not mean that each individual 
plant would achieve the reductions. 

[B] One stakeholder in this group that responded to the survey did not 
answer this question. 

[End of table]

Table 5: Stakeholder Confidence in Achieving Mercury Reductions of 50 
Percent at Nearly Every Plant by 2008: 

Scale of mercury reduction: 50 percent reduction at nearly each power 
plant[A]; Confidence level: Very confident or confident; 
Stakeholder group: Power industry respondents: 2; 
Stakeholder group: Researchers/government officials: 9; 
Stakeholder group: Vendors: 11; 
Total: 22. 

Confidence level: Less confident; 
Stakeholder group: Power industry respondents: 5; 
Stakeholder group: Researchers/government officials: 1; 
Stakeholder group: Vendors: 2; 
Total: 8. 

Confidence level: Not at all confident; 
Stakeholder group: Power industry respondents: 6; 
Stakeholder group: Researchers/government officials: 0; 
Stakeholder group: Vendors: 0; 
Total: 6. 

Confidence level: Do not know; 
Stakeholder group: Power industry respondents: 1; 
Stakeholder group: Researchers/government officials: 1; 
Stakeholder group: Vendors: 0; 
Total: 2. 

Scale of mercury reduction: Total respondents; 
Stakeholder group: Power industry respondents: 14; 
Stakeholder group: Researchers/government officials: 11[B]; 
Stakeholder group: Vendors: 13[B]; 
Total: 38. 

Source: GAO. 

[A] The survey asked stakeholders to consider the likelihood that a 
single power plant could reduce mercury emissions 50 percent by 2008. 
In this case, respondents were asked to consider whether most, but not 
necessarily all, power plants in the United States would each be 
capable of achieving a 50 percent reduction in mercury emissions. 

[B] One stakeholder in this group that responded to the survey did not 
answer this question. 

[End of table]

Table 6: Stakeholder Confidence in Reducing Nationwide Mercury 
Emissions 70 Percent by 2008: 

Scale of mercury reduction: 70 percent reduction nationwidea; 
Confidence level: Very confident or confident; 
Stakeholder group: Power industry respondents: 0; 
Stakeholder group: Researchers/government officials: 6; 
Stakeholder group: Vendors: 10; 
Total: 16. 

Confidence level: Less confident; 
Stakeholder group: Power industry respondents: 1; 
Stakeholder group: Researchers/government officials: 3; 
Stakeholder group: Vendors: 3; 
Total: 7. 

Confidence level: Not at all confident; 
Stakeholder group: Power industry respondents: 13; 
Stakeholder group: Researchers/government officials: 1; 
Stakeholder group: Vendors: 0; 
Total: 14. 

Confidence level: Do not know; 
Stakeholder group: Power industry respondents: 0; 
Stakeholder group: Researchers/government officials: 1; 
Stakeholder group: Vendors: 0; 
Total: 1. 

Scale of mercury reduction: Total respondents; 
Stakeholder group: Power industry respondents: 14; 
Stakeholder group: Researchers/government officials: 11[B]; 
Stakeholder group: Vendors: 13[B]; 
Total: 38. 

Source: GAO. 

[A] GAO asked stakeholders how confident they were that power plants 
could reduce mercury emissions 70 percent by 2008. In this case, 
respondents were asked to consider reductions averaged across power 
plants in the United States, which does not mean that each individual 
plant would achieve the reductions. 

[B] One stakeholder in this group that responded to the survey did not 
answer this question. 

[End of table]

Table 7: Stakeholder Confidence in Achieving Mercury Reductions of 70 
Percent at Nearly Every Plant by 2008: 

Scale of mercury reduction: 70 percent reduction at nearly each power 
plant[A]; 
Confidence level: Very confident or confident; 
Stakeholder group: Power industry respondents: 0; 
Stakeholder group: Researchers/government officials: 5; 
Stakeholder group: Researchers/government officials: 5; 
Stakeholder group: 7; 
Total: 12. 

Confidence level: Less confident; 
Stakeholder group: Power industry respondents: 1; 
Stakeholder group: Researchers/government officials: 4; 
Stakeholder group: Researchers/government officials: 4; 
Stakeholder group: 5; 
Total: 10. 

Confidence level: Not at all confident; 
Stakeholder group: Power industry respondents: 13; 
Stakeholder group: Researchers/government officials: 1; 
Stakeholder group: Researchers/government officials: 1; 
Stakeholder group: 1; 
Total: 15. 

Total respondents: Do not know; 
Stakeholder group: Power industry respondents: 0; 
Stakeholder group: Researchers/government officials: 1; 
Stakeholder group: 0; 
Total: 1. 

Scale of mercury reduction: Total respondents; 
Stakeholder group: Power industry respondents: 14; 
Stakeholder group: Researchers/government officials: 11[B]; 
Stakeholder group: Vendors: 13[B]; 
Total: 38. 

Source: GAO. 

[A] The survey asked stakeholders to consider the likelihood that a 
single power plant could reduce mercury emissions 70 percent by 2008. 
In this case, respondents were asked to consider whether most, but not 
necessarily all, power plants in the United States would each be 
capable of achieving a 70 percent reduction in mercury emissions. 

[B] One stakeholder in this group that responded to the survey did not 
answer this question. 

[End of table]

Table 8: Stakeholder Confidence in Reducing Nationwide Mercury 
Emissions 90 Percent by 2008: 

Scale of mercury reduction: 90 percent reduction nationwide[A]; 
Confidence level: Very confident or confident; 
Stakeholder group: Power industry respondents: 0; 
Stakeholder group: Researchers/government officials: 2; 
Stakeholder group: Vendors: 2; 
Total: 4. 

Confidence level: Less confident; 
Stakeholder group: Power industry respondents: 1; 
Stakeholder group: Researchers/government officials: 2; 
Stakeholder group: Vendors: 6; 
Total: 9. 

Confidence level: Not at all confident; 
Stakeholder group: Power industry respondents: 13; 
Stakeholder group: Researchers/government officials: 6; 
Stakeholder group: Vendors: 5; 
Total: 24. 

Confidence level: Do not know; 
Stakeholder group: Power industry respondents: 0; 
Stakeholder group: Researchers/government officials: 1; 
Stakeholder group: Vendors: 0; 
Total: 1. 

Scale of mercury reduction: Total respondents; 
Stakeholder group: Power industry respondents: 14; 
Stakeholder group: Researchers/government officials: 11[B]; 
Stakeholder group: Vendors: 13[B]; 
Total: 38. 

Source: GAO. 

[A] GAO asked stakeholders how confident they were that power plants 
could reduce mercury emissions 90 percent by 2008. In this case, 
respondents were asked to consider reductions averaged across power 
plants in the United States, which does not mean that each individual 
plant would achieve the reductions. 

[B] One stakeholder in this group that responded to the survey did not 
answer this question. 

[End of table]

Table 9: Stakeholder Confidence in Achieving Mercury Reductions of 90 
Percent at Nearly Every Plant by 2008: 

Scale of mercury reduction: 90 percent reduction at nearly each power 
plant[A]; Confidence level: Very confident or confident; 
Stakeholder group: Power industry respondents: 0; 
Stakeholder group: Researchers/government officials: 2; 
Stakeholder group: Vendors: 2; 
Total: 4. 

Confidence level: Less confident; 
Stakeholder group: Power industry respondents: 1; 
Stakeholder group: Researchers/government officials: 2; 
Stakeholder group: Vendors: 6; 
Total: 9. 

Confidence level: Not at all confident; 
Stakeholder group: Power industry respondents: 13; 
Stakeholder group: Researchers/government officials: 6; 
Stakeholder group: Vendors: 4; 
Total: 23. 

Confidence level: Do not know; 
Stakeholder group: Power industry respondents: 0; 
Stakeholder group: Researchers/government officials: 1; 
Stakeholder group: Vendors: 1; 
Total: 2. 

Total respondents; 
Stakeholder group: Power industry respondents: 14; 
Stakeholder group: Researchers/government officials: 11[B]; 
Stakeholder group: Vendors: 13[B]; 
Total: 38. 

Source: GAO. 

[A] The survey asked stakeholders to consider the likelihood that a 
single power plant could reduce mercury emissions 90 percent by 2008. 
In this case, respondents were asked to consider whether most, but not 
necessarily all, power plants in the United States would each be 
capable of achieving a 90 percent reduction in mercury emissions. 

[B] One stakeholder in this group that responded to the survey did not 
answer this question. 

[End of table]

[End of section]

Appendix VI: Sorbent Injection Cost Estimates from EPA and DOE: 

This appendix summarizes estimates of the cost of activated carbon 
injection reported by EPA and DOE in October and November 
2003.[Footnote 50]

Environmental Protection Agency. Using modeling data provided in EPA's 
cost report, we selected control cost scenarios that are comparable to 
those DOE presented in its cost study.[Footnote 51] These estimates 
include the cost of fly ash disposal for plants that use sorbent 
injection without a fabric filter, based on the assumption that the 
presence of sorbent in fly ash makes it unsuitable for sale. EPA 
provided capital costs in dollars per unit of generating capacity, and 
operating and maintenance costs in dollars per unit of electricity 
generated (per hour) for 100-and 975-megawatt plants operating at 65 
percent capacity over the course of a year (5,694 hours). Tables 10 and 
11 present the range of capital and operating and maintenance costs for 
the selected EPA plant scenarios; capital costs are in total dollars 
while operating and maintenance costs are expressed in dollars per 
year. 

Table 10: Select EPA Cost Estimates of Sorbent Injection for a 100-
Megawatt Coal-Fired Power Plant, 2003: 

Thousands of 2003 dollars. 

Cost: Capital; 
Low estimate: $16.5[B]; 
High estimate: $5,947.9; 
Low-end assumptions: 50 percent mercury removal from bituminous-fired 
unit with existing equipment only; costs include mercury monitoring; 
High-end assumptions: 90 percent mercury removal from sorbent injection 
and fabric filter retrofit, as well as mercury monitoring for a 
subbituminous-fired unit. 

Cost: Annual operating and maintenance[A]; 
Low estimate: $0.6[B]; 
High estimate: $1,342.6; 
Low-end assumptions: 50 percent mercury removal with existing equipment 
only; no sorbent injection needed; 
High-end assumptions: 90 percent mercury removal from sorbent injection 
without a fabric filter and mercury monitoring for bituminous-fired 
unit. 

Source: GAO analysis of EPA data. 

[A] Based on a plant capacity factor of 65 percent, includes both 
variable and fixed operating and maintenance costs. 

[B] This reduction is assumed to be met with existing equipment; 
therefore costs are for mercury monitoring only, no sorbent injection. 

[End of table]

Table 11: Select EPA Cost Estimates of Sorbent Injection for a 975-
Megawatt Coal-Fired Power Plant, 2003: 

Thousands of 2003 dollars. 

Cost: Capital; 
Low estimate: $91.7[B]; 
High estimate: $36,210.5; 
Low-end assumptions: 50 percent mercury removal from bituminous-fired 
unit with existing equipment only; costs include mercury monitoring; 
High-end assumptions: 90 percent mercury removal from sorbent injection 
and fabric filter retrofit, as well as mercury monitoring for a 
subbituminous-fired unit. 

Cost: Annual operating and maintenance[A]; 
Low estimate: 5.6[B]; 
High estimate: $12,868.7; 
Low-end assumptions: 50 percent mercury removal with existing equipment 
only; no sorbent injection needed; 
High-end assumptions: 90 percent mercury removal from sorbent injection 
without a fabric filter and mercury monitoring for bituminous-fired 
unit. 

Source: GAO Analysis of EPA data. 

[A] Based on a plant capacity factor of 65 percent, includes both 
variable and fixed operating and maintenance costs. 

[B] This reduction is assumed to be met with existing equipment; 
therefore costs are for mercury monitoring only, no sorbent injection. 

[End of table]

EPA estimated that the capital cost of sorbent injection for a 100-
megawatt plant would range from $0.17 to $59.5 per kilowatt of 
capacity, while operating and maintenance costs for the same plant 
would range from $0.001 to $2.36 per megawatt-hour. For the 975-
megawatt plant, EPA estimated that the capital cost would range from 
$0.09 to $37.1 per kilowatt, while operating and maintenance costs 
would range from $0.001 to $2.32 per megawatt-hour. EPA also estimated 
the total annualized cost of these controls in 2003 dollars, which 
ranged from $0.005 to $2.64 per megawatt-hour or between $2,847 and 
$1.5 million per year for a 100-megawatt plant.[Footnote 52] For a 975-
megawatt plant, annualized costs ranged from $0.003 to $2.45 per 
megawatt-hour or between $16,655 and $13.6 million per year. 

Capital costs were much higher for scenarios where a fabric filter was 
installed, while the highest operating and maintenance cost and 
annualized cost were for achieving a 90 percent mercury reduction for a 
bituminous coal-fired plant using sorbent injection without installing 
a fabric filter, due to the amount of sorbent needed to achieve a high 
mercury removal. At the low end of these costs, EPA assumed that 
existing equipment is sufficient to achieve a 50 percent reduction in 
mercury for plants that burn bituminous coal, therefore costs reflect 
only that of monitoring mercury emissions and do not include actual 
sorbent injection costs. While total capital and annual costs for the 
larger plant were higher than for the smaller plant, the annualized 
cost in dollars per megawatt-hour was actually lower, since costs were 
spread out over more units of capacity and electricity generated. 

Department of Energy. DOE's analysis of the cost of mercury control 
technologies was based on field testing conducted by DOE's National 
Energy Technology Laboratory. For its estimates, DOE used a 
hypothetical power plant of 500 megawatts burning bituminous or 
subbituminous coal and equipped with an electrostatic precipitator or a 
layout that consists of sorbent injection and a fabric filter 
retrofitted downstream of an existing electrostatic precipitator. Cost 
estimates were developed for mercury removal requirements ranging from 
50 to 90 percent as shown below in table 12. DOE estimated capital 
costs between $1.97 and $57.44 per kilowatt. The high end of the 
capital cost range represented cases where facilities installed a 
supplemental fabric filter to achieve higher levels of mercury 
reduction, while the high end of the operating and maintenance costs 
represented achieving a 90 percent reduction in mercury emissions for a 
plant burning bituminous coal using sorbent injection without a fabric 
filter. 

Table 12: DOE's Cost Estimates for Sorbent Injection Installed on a 500-
Megawatt Coal Power Plant, 2003: 

Thousands of 2003 dollars. 

Cost: Capital; 
Low estimate: $984.0; 
High estimate: $28,719.0; 
Low-end assumptions: 50 or 70 percent mercury removal from bituminous-
fired unit, 50 or 60 percent mercury removal from subbituminous-fired 
unit with sorbent injection and existing equipment (no fabric filter); 
High-end assumptions: 60 or 90 percent mercury removal with sorbent 
injection and fabric filter installation for a subbituminous-fired 
unit. 

Cost: First year operating and maintenance; 
Low estimate: 931.0; 
High estimate: $15,647.0; 
Low-end assumptions: 50 percent mercury removal with sorbent injection 
and existing equipment (no fabric filter) from bituminous-fired unit; 
High-end assumptions: 90 percent mercury removal with sorbent injection 
and existing equipment (no fabric filter) from bituminous-fired unit. 

Source: GAO analysis of DOE data. 

[End of table]

DOE also provided two sets of annualized cost estimates, one that 
included a projected impact for the loss of fly ash sales and one that 
did not. Without a by-product impact, DOE estimated annualized costs to 
range from $0.37 to $5.72 per megawatt-hour, which equates to about 
$1.3 million to $20.0 million per year. Estimates with the by-product 
impact ranged from $1.82 to $8.14 per megawatt-hour, which equates to 
about $6.4 million to $28.5 million per year. At the high end, these 
estimates represented the cost of achieving a 90 percent mercury 
reduction at a bituminous-coal fired plant with sorbent injection, an 
existing electrostatic precipitator, and no fabric filter. The low-end 
cost without a by-product impact represented a 50 percent mercury 
reduction at a bituminous-fired plant using sorbent injection with an 
electrostatic precipitator, while the low-end cost with a by-product 
impact was for the same configuration and mercury reduction, but at a 
subbituminous-fired plant. 

In addition, DOE's cost estimates suggest that plants may achieve a 
high level of mercury control without a fabric filter. While achieving 
a higher mercury removal rate without a fabric filter would require 
more sorbent, plants can decide what air pollution control 
configuration is most cost effective. Furthermore, according to EPA, 
test results suggest that chemically enhanced sorbent may prove more 
efficient than activated carbon in achieving high levels of mercury 
removal at relatively modest injection rates, and thus less expensive 
to use. According to EPA, tests of these sorbents have achieved mercury 
removal rates of 40 to 94 percent without a fabric filter, with the 
highest removal rate achieved during a continuous 30-day test (the 
longest reported test of these sorbents). Therefore, some facilities 
seeking to achieve high levels of mercury reduction may not have to 
incur the substantial cost of adding a fabric filter. 

[End of section]

Appendix VII: GAO Contact and Staff Acknowledgments: 

GAO Contact: 

John B. Stephenson (202) 512-3841: 

Acknowledgments: 

In addition to the contact named above, Kate Cardamone, Christine B. 
Fishkin, Tim Guinane, Michael Hix, Andrew Huddleston, Judy Pagano, and 
Janice Poling made key contributions to this report. Nabajyoti 
Barkakati, Cindy Gilbert, Jon Ludwigson, Stuart Kaufman, Cynthia 
Norris, Katherine Raheb, Keith Rhodes, and Amy Webbink also made 
important contributions. 

(360555): 

FOOTNOTES

[1] In this report, "power plants" refers to coal-fired electricity 
generating units larger than 25 megawatts in size that produce 
electricity for sale. 

[2] The 48 ton emissions level reflects reductions in mercury emissions 
achieved by existing controls for other pollutants. In this report, we 
use the amount of mercury in coal that is burned by power plants (75 
tons) as a baseline when discussing the effectiveness of mercury 
controls. 

[3] The technology-based approach is commonly known as the Maximum 
Achievable Control Technology (MACT) approach. 

[4] For information about EPA's economic analysis of the mercury 
control options, see our related report, GAO, Clean Air Act: 
Observations on EPA's Cost-Benefit Analysis of Its Mercury Control 
Options, GAO-05-252 (Washington, D.C.: Feb. 28, 2005). 

[5] EPA has estimated that power plants will achieve emissions 
reductions beyond the 38 ton cap in 2010 and then use the resulting 
emissions allowances to comply with the more stringent cap for 2018, 
resulting in actual mercury emissions of about 31 tons in 2010 and 
about 26 tons in 2018. Relative to the estimated 75 tons of mercury in 
coal, this equals a 59 percent reduction in 2010 and a 65 percent 
reduction in 2018. 

[6] The main types of coal burned, in decreasing order of rank, are 
bituminous, subbituminous, and lignite. Rank is the coal classification 
system based on factors such as the heating value of the coal. High-
rank coal generally has relatively high heating values (i.e., heat per 
unit of mass when burned) compared with low rank coals, which have 
relatively low heating values. 

[7] We did not assess the effectiveness of controls for other 
pollutants in capturing mercury as a side benefit because EPA had 
already conducted an extensive analysis of that topic. 

[8] Nitrogen oxides and sulfur dioxide contribute to acid rain and the 
formation of fine particles that have been linked to aggravated asthma, 
chronic bronchitis, and premature death. Nitrogen oxides also 
contribute to the formation of ozone, a regulated pollutant, when they 
react with volatile organic compounds in the presence of heat and 
sunlight. 

[9] The interstate rule requires further reductions in nitrogen oxide 
and sulfur dioxide emissions in 2009 and 2010, respectively. 

[10] According to EPA, a large share of the mercury captured under the 
two rules will be its forms that are of greatest concern with respect 
to deposition in the United States and eventual uptake by freshwater 
aquatic organisms. 

[11] Multipollutant controls do not include those that are intended to 
capture other pollutants that may also remove some mercury. 

[12] As stated in appendix I, we focused our data collection on tests 
at actual power plants. The tests at power plants were conducted on 
varying scales, with some controls applied to a diverted fraction of 
the flue gas and other controls--primarily the sorbents--applied to the 
entire stream of flue gas, e.g., full-scale tests. 

[13] The longest continuously operating test lasted for 5 months as 
part of a yearlong project at a plant in Wilsonville, Alabama. 

[14] Thirteen of the 14 power industry respondents also identified 
inadequate performance guarantees and the belief that technologies are 
unproven as reasons for not installing mercury controls. 

[15] In our survey, we asked respondents separate questions about 
mercury controls addressing their availability for purchase, their 
effectiveness, and the need for further testing. 

[16] EPA, Office of Research and Development, Control of Mercury 
Emissions from Coal Fired Electric Utility Boilers: An Update (Research 
Triangle Park, N.C., Feb. 18, 2005). 

[17] We obtained data about 55 field tests, 39 of which are part of 
DOE's mercury control research and development program. As of February 
2005, long-term testing was either planned or had not been completed at 
26 of the 39 DOE-funded field tests. Sixteen of the 55 field tests we 
reviewed were identified by survey respondents and did not correspond 
to DOE-funded tests. 

[18] These data consider the amount of mercury in coal--75 tons--as the 
baseline for estimating the percent mercury reduction. 

[19] One test on lignite coal also used a sorbent enhancement, i.e. 
additional chemicals to improve mercury capture. 

[20] DOE has required most projects in this round of testing to last at 
least for 1 month. The exact duration of these tests has not yet been 
determined. 

[21] We asked respondents to consider the amount of mercury in coal--75 
tons--as the baseline when considering each mercury reduction. 

[22] This would result in nationwide emissions of 37.5 tons per year, 
given the baseline of 75 tons of mercury in coal. 

[23] The number of survey responses exceeds the number of survey 
participants because technology vendors were given the option of 
submitting a survey for each technology they produce. Five of the 14 
technology vendors submitted two surveys. 

[24] Environmental Protection Agency, Office of Research and 
Development, National Risk Management Research Laboratory, Performance 
and Cost of Mercury and Multipollutant Emission Control Technology 
Applications on Electric Utility Boilers (Research Triangle Park, N.C., 
2003). 

Jeff Hoffmann and Jay Ratafia-Brown, Science Applications International 
Corporation, Preliminary Cost Estimate of Activated Carbon Injection 
for Controlling Mercury Emissions from an Un-Scrubbed 500 MW Coal-Fired 
Power Plant, a report prepared for the Department of Energy, National 
Energy Technology Laboratory, November 2003. 

[25] A megawatt is a unit of power equal to one million watts, or 
enough electricity to power about 750 homes at any given time. 

[26] According to a DOE official, the varying assumptions regarding the 
plant capacity factor reflect different assumptions about which coal-
fired power plants will use sorbent technologies. 

[27] According to EPA, while 36 percent is an average removal rate for 
bituminous coals, the 50 percent rate they used in this case was based 
on specific assumptions about a particular type of bituminous coal in 
the scenario they analyzed. 

[28] Costs expressed in dollars per megawatt-hour and mills per 
kilowatt-hour are numerically equal. 

[29] When combined with existing equipment, advanced dry scrubbers were 
estimated to achieve mercury removal rates between 96 and 99 percent in 
EPA's models. 

[30] In calculating these estimates, EPA assumed that the unit capital 
cost could vary by as much as 20 percent, while operating and 
maintenance costs were calculated assuming a range of reagent costs 
that varied by as much as plus or minus $20 per ton. Due to these 
variations, cost ranges presented in unit costs, such as dollars per 
kilowatt, do not always match the calculated cost ranges in total 
dollars for a plant of a given size. 

[31] In estimating costs for advanced dry scrubbers, EPA only presented 
costs for plants burning bituminous coal. 

[32] Anne Smith et al., Charles River Associates , and John H. Wile, 
E&MC Group, Projected Mercury Emissions and Costs of EPA's Proposed 
Rules for Controlling Utility Sector Mercury Emissions (Washington, 
D.C., 2004). 

[33] These formulas allow capital and fixed operating and maintenance 
costs to vary by the size of the plant and allow variable operating and 
maintenance costs to vary depending on the desired level of mercury 
reduction. 

[34] MJ Bradley also presented cost estimates for sorbent injection, 
but presented the same cost information reported by DOE. 

[35] M.J. Bradley & Associates, Status of Development of Mercury 
Control Technologies (Concord, Mass., Aug. 5, 2004). 

[36] Calculated annual operating and maintenance costs assume a 500-
megawatt plant operating at 80 percent capacity, i.e. 7008 hours per 
year. 

[37] EPA's estimates suggest that the installation of the fabric filter 
is more cost-effective than carbon injection alone to achieve an 80 
percent mercury reduction at a 975-megawatt plant and a 90 percent 
mercury reduction at both the 100-and 975-megawatt plants. 

[38] DOE's estimates indicate that for a plant that sells its fly ash, 
loss of fly ash sales and related disposal costs could increase the 
cost of mercury removal by between $31,232 and $213,133 per pound of 
mercury removed for a plant using activated carbon injection with an 
existing electrostatic precipitator. Costs vary depending on the type 
of coal burned and the desired level of mercury reduction. For example, 
the cost per pound of mercury removed for a 50 percent mercury 
reduction at a bituminous coal-fired plant increases from $32,598 to 
$245,731 when accounting for the potential impact in lost fly ash 
sales. EPA estimated that using current technology, the marginal cost 
of mercury control will be $23,200; $30,100; and $39,000 per pound of 
mercury removed in 2010, 2015, and 2020 respectively (in 1999 dollars). 
EPA also conducted a sensitivity analysis--assuming that mercury 
controls will improve over time and therefore cost less--that showed 
this marginal cost falling to $11,800; $15,300; and $19,900 
respectively in 2010, 2015, and 2020. These mercury removal analyses 
were conducted by EPA using the Integrated Planning Model, and are 
therefore based on different assumptions and modeling efforts than 
those that went into the 2003 mercury control cost report. 

[39] Part of the fall in acid rain costs is due to lower costs of 
transportation, since the deregulation of rail made it cheaper to ship 
low-sulfur coal greater distances. 

[40] Based on studies by the Electric Power Research Institute and the 
Massachusetts Institute of Technology that showed operating and 
maintenance costs decline from $17.3 per megawatt-hour to $3.34 per 
megawatt-hour in 1999 dollars. 

[41] Results from nonprobability samples cannot be used to make 
inferences about a population because in a nonprobability sample some 
elements of the population being studied have no chance or an unknown 
chance of being selected as part of the sample. 

[42] We received responses from 41 stakeholders, but 2 of these 
respondents completed one survey together in order to describe a 
product produced by both companies. Because the 2 stakeholders 
completed one survey for one mercury control, we counted this as one 
response as part of our survey analysis. 

[43] The policy stakeholders we interviewed did not participate in the 
three surveys we conducted. 

[44] We conducted 14 interviews with stakeholders representing these 13 
organizations. In order to include the perspective of several senior 
air policy staff at EPA, we conducted two interviews with the agency. 

[45] The Clean Air Interstate Rule revised these provisions of the Acid 
Rain Program to require additional allowances beginning in the year 
2010. 

[46] Based on the annualized capital and operating costs of the 
technologies units are expected to use and the number of units expected 
to use each technology. 

[47] Ten of the 14 vendors were not asked to provide views on the 
availability of activated carbon because these vendors do not produce, 
develop, or sell this technology. 

[48] GAO instructed respondents to consider whether such reductions 
were feasible at most, but not all, power plants. This allowed survey 
respondents to report confidence in mercury reduction at nearly all 
power plants without considering highly unusual situations that might 
arise at certain plants. 

[49] This number differs from the number of responses because two of 
the 40 respondents did not answer these questions. 

[50] Environmental Protection Agency, Office of Research and 
Development, National Risk Management Research Laboratory, Performance 
and Cost of Mercury and Multipollutant Emission Control Technology 
Applications on Electric Utility Boilers (Research Triangle Park, N.C., 
2003). 

Jeff Hoffmann and Jay Ratafia-Brown, Science Applications International 
Corporation, Preliminary Cost Estimate of Activated Carbon Injection 
for Controlling Mercury Emissions from an Un-Scrubbed 500 MW Coal-Fired 
Power Plant, a report prepared for the Department of Energy, National 
Energy Technology Laboratory, November 2003. 

[51] According to the EPA study, the agency identified a representative 
range of plant configurations, coal types, and technologies. In 
developing the range, EPA used 49 model plants. For the estimates 
presented here, we selected 4 model plants, which were 100-megawatt and 
975-megawatt plants with an existing electrostatic precipitator, 
burning low-sulfur bituminous or subbituminous coals with and without a 
fabric filter installed, with desired mercury removal levels between 50 
and 90 percent, depending on configuration and coal type. These model 
plants most closely align with the assumptions presented in the DOE 
cost estimates discussed in this report. 

[52] EPA's annualized cost reflects the capital cost annuitized using a 
levelized carrying charge rate of 13.3 percent assuming a 30-year 
operating period summed with operating and maintenance costs levelized 
with a factor of 1.0. 

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