Clean Air Act
Emerging Mercury Control Technologies Have Shown Promising Results, but Data on Long-Term Performance Are Limited Gao ID: GAO-05-612 May 31, 2005In 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.
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.
GAO-05-612, Clean Air Act: Emerging Mercury Control Technologies Have Shown Promising Results, but Data on Long-Term Performance Are Limited
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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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