Addition for Subtraction: The New Math of Air Pollution Control for

A Quarterly Publication of Zephyr Environmental Corporation | APRIL 2015
Addition for Subtraction: The New Math of Air
Pollution Control for Coal Plants
O
ver the past decade, coal-fired power generators have been in a near constant “plan
ahead” mode to get controls in place to
comply with the federal Clean Air Visibility Rule,
Clean Air Mercury Rule (subsequently vacated),
Clean Air Interstate Rule, Cross-State Air Pollution Rule, and Mercury and Air Toxics Standards
(MATS), as well as state rules and statutes such as
the Maryland Healthy Air Act of 2006. Many coalfired units have been shut down in recent years and
more will continue to close in the near future due to
the high costs of compliance with these regulations.
But many units will be able to operate for years to
come because of the evolving use of additives to control emissions.
Just ten years ago, options for effectively controlling emissions of regulated pollutants from coal-fired
boilers were limited primarily to expensive add-on
equipment, such as scrubbers. Today, however, welltested, proven, and cost-effective emissions control
methods involving the use of chemical additives
and sorbent materials are on the market. Given the
variety of coal types (e.g., bituminous, subbituminous) and boiler types (e.g., cyclone boiler, circulating fluidized bed boiler, pulverized coal boiler), a
variety of additives have been developed, primarily
aimed at reducing emissions of mercury (Hg), sulfur
dioxide (SO2), nitrogen oxides (NOx), and hydrogen
chloride (HCl).
To reduce Hg emissions, a liquid halide salt solution
can be sprayed on the coal. The halide oxidizes elemental Hg generated by coal combustion to a form
that is water-soluble and, therefore, easily removed
from the exhaust stream with an existing wet scrubber. Hg control efficiencies are highest when firing
western subbituminous coal, which is an inherently
low-halogen (or low-chloride content) coal. Other
c o n s u l t i n g
u
additives can be added to the coal in solid or liquid
form to reduce NOx emissions directly, or to lock-up
gas-phase chemicals generated by combustion that
can poison catalysts in a selective catalytic reduction
system downstream of the boiler. These additives
can also improve boiler efficiency and operating
reliability.
The American Jobs Creation Act of 2004 created a
federal tax credit to incentivize the use of coal treated
with additives (“refined coal”) to reduce coal boiler
Hg and NOx emissions. Emission reductions of at
least 40 percent for Hg and 20 percent for NOx must
be demonstrated to qualify for the credit ($6.60 per
ton of refined coal burned in 2014), which doesn’t
expire until December 31, 2021. Many utilities have
taken advantage of this change to the tax code to install refined coal systems, which have been approved
for use at dozens of plants, yielding significant, relatively inexpensive emission reductions.
Operators of coal-fired units, especially those without
scrubbers, are concerned with meeting the HCl emission limit imposed by the MATS. To comply, many
plants use dry sorbent injection (DSI) technology, in
t r a i n i n g
coal plants >>> continued on page 8
u
d a t a
s y s t e m s
FROM THE TRENCHES
Bienvenue Clement et Elena!
Clement: Elena and I are two of the newest engineers at Zephyr’s
Austin office. And we go way back! By that I mean 5,000 miles,
all the way back to Lille, France. I started my undergraduate
engineering education at École Centrale de Lille, where I had
my first encounter with environmental engineering, as well as
with my future colleague.
As a first year student, I worked with the French car manufacturer Renault to develop new ways to incorporate solar panels
in automobiles to meet some of the cars’ electrical and power
requirements and thus reduce fuel consumption and associated
air pollutant emissions. This was a very interesting and innovative introduction to the field of air pollution control.
I knew this was a field I would like to study further. Sadly, my
cold, rainy, and cloudy school in northern France did not offer any
specialization in this field. But the warm, dry, and sunny University of Texas at Austin did! As I started my second year in Lille
with my eyes set on an exchange program abroad, I was assigned
a first year student to guide me through the first weeks of class.
Strangely, all my attempts at contacting Elena before the first day
of school were unsuccessful.
Elena: As long as I was home, Clement would have no luck indeed. Back in the day, French cell phones did not come with
service that reached a small island in the Indian Ocean, 6,000
miles from Lille. That’s right, I’m from Reunion. If you’re picturing a Hawaii-like island near Madagascar, with a burning
sun, a plethora of exotic fruits, an active volcano, and seemingly
unlimited fields of sugar cane, you are correct.
When time came for my summer internship as a second year
engineering student, I decided to intern as a sales consultant
engineer for a firm specializing in the design and construction of
water treatment plants. After a crash course on the physics and
chemistry of water treatment, I prepared promotional materials,
spent countless hours on the phone setting up meetings, and off
I went! I spent my summer driving from town to town (without
the help of Google Maps!), meeting with technicians and politicians alike, listening to their water treatment needs and offering
potential solutions.
From this great experience I learned autonomy and peeked into
the field of consulting. And being involved in solving environmental issues definitely felt right to me. I had one more year to
finish my Master’s degree in France and figure out what might be
next. On the other side of the Atlantic, Clement seemed to really
enjoy his time as a graduate student.
2
Clement: In June 2010, while I was in graduate school, I had the
opportunity to travel to Copenhagen, Denmark. Our goal was
to study building materials that can be used indoors to improve
air quality by reducing levels of a family of air pollutants, called
aldehydes. Back in Austin, we had shown that the use of specific
materials led to lower levels of aldehydes in the air. We selected
the Danish Technical University to perform our field research
because of their capability to conduct human air quality perception studies. The idea was to survey how people’s perception of
air quality was affected when using various building materials
and if subtle changes in air pollutants levels were noticeable by
humans. And they were! That was a valuable experience, giving a human dimension to my laboratory research. In the meantime, Elena was also off to a new country . . .
Elena: Brazil! Now convinced that I belonged in the environmental field, I began probing my interest for research. That’s how
I found myself at the Oceanography Institute of the University
of Sao Paulo. I spent two months surrounded by a pile of books
and articles in Portuguese and English (and thankfully an online
translator!), reading about microalgae and copepods travelling
across oceans in the ballasts of large commercial ships. This introduction to the notion of invasive species opened my eyes to the
various meanings of pollution.
I then moved to the small coastal city of Ubatuba for some lab
work. By a stroke of luck, I was assigned a lab mate who was a
visiting American grad student! This experience really turned out
to be the perfect transition for the next step in my journey: UT
Austin. After all, Clement had been telling me how great their
Indoor Air Quality Program was.
trenches >>> continued on page 6
AN ATTORNEY’S PERSPECTIVE
Tips For Defending An Environmental Citizen Suit
C
itizen suits under the federal environmental laws are being
filed with increased frequency, and with the reduced enforcement budgets of the EPA and the states, this trend is expected
to continue. This trend is further enhanced by government efforts
to improve regulatory transparency and electronic availability of
data submitted by regulated entities, which have increased the
amount of and speed with which members of the public can access information about potential regulatory violations. Developers, states, environmental groups, and even economic competitors
can be citizen plaintiffs.
The citizen suit provisions in the roughly 18 federal laws that
contain such provisions share many similarities, but the specific
language of the applicable statute will determine how an individual citizen suit will proceed. That being said, there are some
common strategies to keep in mind to avoid or defend against
most citizen suits.
Notice. Most citizen suit statutes require plaintiffs to provide 60
days’ notice before filing a lawsuit. The purpose of the notice
period is to provide opportunities for the relevant agency to take
enforcement and the regulated entity to achieve compliance before a suit is initiated. Strict compliance with the notice provisions
is required, and improper notice may be a basis for challenging
a suit. It is important that the recipient of such a notice take
prompt action because, in most cases, correcting the alleged
violation before suit is filed may deprive the federal court of
jurisdiction to hear the case or otherwise moot the lawsuit.
Ongoing violations. Most environmental statutes require some level
of current or continuing violations by a defendant at the time a
citizen lawsuit is filed. Certain historical air violations that are repeated may also be a basis for a citizen suit. Compliance after a suit
is filed may not divest the court of jurisdiction if a violation was
continuing or is likely to recur at the time the complaint is filed.
Agency action. In many situations, a governmental agency has
already initiated an enforcement action to address violations, but
not all government action is sufficient to block the lawsuit from
going forward. Civil actions in court, and some administrative
actions, can preclude a federal court from having jurisdiction
over the citizen suit if the action is being “diligently prosecuted”
by the government. Recovery of the economic benefit of noncompliance is often key to demonstrating diligent prosecution
by the government.
Evidence. Defendants to a citizen suit can and should plan a
comprehensive approach to the development of facts and regulatory
interpretations to counter the citizen plaintiff’s allegations. In
addition, citizen plaintiffs must be held to their burden of
proving violations, their impacts, any resulting economic benefit, and justifying the relief requested. For example, in the recent
decision of Environment Texas Citizen Lobby, Inc. v. ExxonMobil
Corporation et al., the court found that the plaintiffs had largely
failed to link their health and environmental claims to the
alleged violations. Further, evidence of a systematic compliance
program that encompasses evaluation, analysis, and correction
can be helpful in mitigating penalties and injunctive relief in
these cases.
Penalties. Statutory maximum penalties can be as high as $37,500
for each day of violation. Because of a wide range of possible
environmental violations, courts must consider certain factors in
assessing penalties (e.g., seriousness and duration of the violations,
compliance history and size of the defendant, payment of penalties, and any economic benefit of noncompliance). These factors
can influence the amount of a penalty up or down at the judge’s
discretion. In some situations, even where citizen plaintiffs can
show that violations have occurred, courts are not bound to impose the maximum penalty allowed or any penalty for violations.
Attorneys’ fees. Awards of attorneys’ fees are generally permissible in citizen suits when a party has had some measure of success
and the court determines an award is appropriate. Calculating
the fee amount is highly discretionary, but recovery is not limited to citizen plaintiffs. As demonstrated in Sierra Club v. Energy
Future Holdings Corporation and Luminant Generation Company LLC, defendants may be awarded attorneys’ fees where it is
perspective >>> continued on page 6
3
News Briefs
national news
Interior Department Issues New Fracking Rules
On March 20, the U.S. Department of Interior (DOI)
issued the nation’s first major federal regulations to
protect groundwater from contamination by hydraulic fracturing (fracking) activities used in the oil and
gas industry. The new rules, which are to take effect
in late June and will only regulate oil and gas wells
drilled on public lands, focus on the safety and
integrity of concrete used to case wells and the disclosure of chemicals used in the fracking process.
The regulations will also set safety standards for the
storage of used fracking chemicals at well sites and will
require companies to submit geological information
to the Bureau of Land Management (BLM). For more
information, contact Steve McVey at 512.879.6625 or
[email protected].
EPA to Issue Final Power Plant Carbon
Pollution Rules
This summer, EPA plans to issue its final rules for
curbing power plant greenhouse gas emissions: the
Clean Power Plan for existing power plants (see July
2014 issue of Currents) and the Carbon Pollution
Standards for new, modified, and reconstructed power
plants. The final version of the carbon pollution standards should have been issued by January 2015 to satisfy
the Clean Air Act deadline; however, to address the
flood of comments on both sets of rules, EPA postponed
the final carbon pollution standards by six months,
with concurrent issuance of both standards expected
this summer. States will then be required to submit
their compliance plans to EPA in Summer 2016, although they can submit initial plans with requests for
extension. This summer, EPA also plans to propose a
model federal implementation plan (FIP) to be imposed
on any state that fails to submit a timely and approvable plan for meeting the Clean Power Plan goals. For
more information, contact Lou Corio at 410.312.7912
or [email protected].
White House Announces Actions to
Cut Methane Emissions
On January 14, the White House released its plans to
reduce methane emissions from the oil and gas industry 40 to 45 percent by 2015. To cut emissions of this
greenhouse gas, the administration’s Climate Action
4
Plan proposes new and modified source standards for
methane, enhanced leak detection and repair (LDAR)
requirements, “lead by example” initiatives by BLM,
and coordination with the Pipeline and Hazardous
Materials Safety Administration on pipeline standards
and modernization of gas transmission and distribution infrastructure. For more information, contact Eric
Quiat at 512.579.3823 or [email protected].
EPA to Reverse Oil and Gas Air Emissions
Standard Tank Definition Change
On December 31, 2014, EPA revised the definition
of a “storage vessel” in its NSPS Subpart OOOO air
emissions standards to categorize “two or more storage
vessels connected in parallel” as equivalent to a single
vessel. However, in response to industry comments,
EPA proposed on March 15 to return to the original
definition of “storage vessel” as a single tank.
In a separate action, the Texas Commission on
Environmental Quality (TCEQ) announced that it
would exercise discretion in enforcing the December
31, 2014 definition until April 15, 2016. For more
information, contact Bryan Osborne at 512.579.3815
or [email protected] or contact Thomas Sullivan
at 512.879.6632 or [email protected].
Corps of Engineers Enhance Permit Protections
of Listed Species and Critical Habitats
In accord with a recent Biological Opinion issued by
the National Oceanic and Atmospheric Administration’s National Marine Fisheries Service, the U.S.
Army Corps of Engineers (USACE) announced in December 2014 that it will be enhancing its nationwide
permitting of activities involving discharges of dredged
or filled materials into the waters of the U.S. with additional measures to protect listed endangered or threatened species and critical habitat. The protective measures, to be phased in by the end of 2015, will generally
affect utility line activities, bank stabilization, linear
transportation projects, and boat ramps within those
USACE districts that include coastal habitats. Current
or previously verified nationwide permit activities and
permittees who have not yet completed construction
of an authorized activity should not be affected by the
permit changes. For more information, contact Clay V.
Fischer at 512.879.6629 or [email protected].
EPA Designates Areas Not Meeting 2012
Fine Particle Air Standard
On January 15, EPA finalized the air quality designations for
most areas of the U.S. with respect to meeting the 2012 primary
annual fine particle (PM2.5) National Ambient Air Quality
Standard (NAAQS) of 12 micrograms per cubic meter. Through
these designations, EPA identified 1) areas in nonattainment
based on acceptable air quality monitoring collected from 2011
through 2013, and 2) areas that are contributing to a violation of
the standard in a nearby area. EPA has initially classified all 2012
PM2.5 NAAQS nonattainment areas as “moderate.” In a related
action, on March 10, EPA proposed detailed requirements that
states would have to meet in developing plans to implement the
standards by the 2020 deadline. For more information, contact
Lou Corio at 410.312.7912 or [email protected].
EPA Proposes Amendments to Oil
Discharge Response Rules
In response to lessons learned from handling of the 2010 spill of
oil from the Deepwater Horizon well into the Gulf of Mexico,
on January 22, EPA proposed revisions to its National Oil and
Hazardous Substances Pollution Contingency Plan to address
concerns about the use of dispersants and other chemical and
biological agents to respond to oil discharges into waters of
the U.S. The proposed revisions treat not only the efficacy of
using dispersants, but also long-term environmental impacts,
endangered species effects, and human health impacts of their
use. The rule revisions also include area planning requirements
for authorizing the use of dispersants, toxicity thresholds, and
advanced monitoring techniques. For more information, contact
Molly McKenna at 512.579.3837 or [email protected].
DOT/PHMSA Proposes Amendments to the
Hazardous Materials Regulations
On January 23, the U.S. Department of Transportation Pipeline
and Hazardous Materials Safety Administration proposed to clarify
and simplify its hazardous materials regulations. The proposed
provisions remove the packing group II designation for certain
organic peroxides, self-reactive substances and explosives; add
requirements for the mounting of manifolded acetylene cylinders
on trailers; add requirements to allow for shipments of damaged
wet electric batteries; and revise requirements for the packaging
of nitric acid, testing of pressure relief devices on cargo tanks,
and shipments of black or smokeless powder for small arms.
For more information, contact Linda Salzar at 512.879.6630 or
[email protected].
EPA Revises Definition of Solid Waste
On January 13, EPA finalized revisions to several recycling-related
provisions of its solid waste definition rule including codifying
new definitions, adding recordkeeping and notification requirements, and adding emergency preparedness and response condi-
tions. Through these revisions, EPA hopes to encourage reclamation of hazardous secondary materials and prevent sham recycling.
For more information, contact Betty Moore at 512.879.6622 or
[email protected].
EPA Proposes to Require Electronic Reporting
of Air Emissions Information
On March 20, EPA proposed to require all facilities subject to new
source performance standard reporting requirements to submit
those reports electronically through EPA’s Central Data Exchange
(CDX) rather than submitting them in paper format. This rule
change would not require submittal of any additional information
that is not already required under the current NSPS. Reports
targeted for future electronic submission are those that provide
direct measures of air emissions data such as summary reports,
excess emission reports, performance test reports and performance
evaluation reports. For more information, contact Michele Foss
at 281.668.7342 or [email protected].
EPA Revises Hazardous Emissions Standards for PVC
and Copolymers Production Area Sources
On February 4, EPA revised its Subpart DDDDDD national
emissions standards for hazardous air pollutants to remove the
limit on total non-vinyl chloride organic hazardous air pollutant
(TOHAP) emissions in the process wastewater of existing and
new polyvinyl chloride and copolymers (PVC) production area
sources. This direct action is intended to correct for erroneously
using process data not part of the PVC production source category
in establishing the standard. For more information, contact Bryan
Osborne at 512.579.3815 or [email protected].
EPA Proposes to Amend Definition of VOC to
Exclude t-Butyl Acetate from Recordkeeping and
Reporting Requirements
On February 5, EPA proposed rulemaking and sought public
comment to remove recordkeeping, emissions reporting, photochemical dispersion modeling and inventory requirements related
to the use of tertiary butyl acetate (TBAc) as a VOC. The EPA
has identified TBAc as a negligible contributor to ozone formation and determined past TBAc emission recordkeeping and
reporting requirements, which were unique to TBAc, were not
resulting in useful information. For more information, contact
Lucy Fraiser at 512.879.6652 or [email protected].
EPA Proposes to Require Industry Reporting
of Nanomaterial Information
On April 6, EPA proposed to require the one-time reporting by
industry of information about certain chemical substances that
are or will be manufactured or processed at the nanoscale (i.e., in
sizes in the range of billionths of a meter), including the specific
news briefs >>> continued on page 6
5
news briefs >>> continued from page 5
chemical identity, production volume, methods of manufacture
and processing, exposure and release information, and existing
data concerning environmental and health effects. EPA would
use this information in evaluating whether it should take further
action under the Toxic Substances Control Act to protect human
health and the environment from the effects of manufacturing
and processing nanomaterials. For more information, contact
Michele Foss at 281.668.7342 or [email protected].
state news
TCEQ Proposes to Expand List of Types of Injection
Activities Permissible in Edwards Aquifer
On January 21, the TCEQ approved rulemaking that would
remove the current prohibition on certain types of injection
activities in the Edwards Aquifer, providing for rule authorization
of injection of fresh water withdrawn from the Edwards, and the
injection of rainwater, storm water, flood water, or ground water
via an improved natural recharge feature. The TCEQ is also
proposing to provide for the general permit authorization of
injection wells that can currently be authorized by rule, certain
injection wells that are part of an engineered aquifer storage
facility, and wells used to inject desalination concentrate. For
more information, contact Miranda Briones at 512.879.3957 or
[email protected].
U.S. Water Alliance, a Washington-based environmental nonprofit organization. He previously served as EPA’s Assistant
Administrator for Water and Director of Arizona’s Department
of Environmental Quality. For more information, contact Lou
Corio at 410.312.7912 or [email protected].
PADEP Publishes Draft Final Rules for Oil
and Gas Surface Activities
On April 4, the Pennsylvania Department of Environmental
Protection (PADEP) published an advanced notice of revisions
to its Chapter 78 environmental performance protection standards for oil and gas well sites. The proposed revisions are
intended to better protect water resources and public safety as
well as to address landowner concerns. PADEP anticipates
presenting a final regulation to the Pennsylvania Environmental
Quality Board in late 2015 and finalizing the rule changes in
Spring 2016. For more information, contact Jim Young at
717.942.1202 or [email protected].
New Maryland Secretary of the Environment Confirmed
On March 6, the Maryland State Senate confirmed the appointment of Ben Grumbles as Secretary of the Maryland Department
of the Environment. Secretary Grumbles had been nominated
for the position by Governor Larry Hogan in January. From 2010
until his nomination, Secretary Grumbles was President of the
PADEP Finalizes Revisions to GP-5 Air Permit
for Natural Gas Facilities
On January 31, PADEP finalized revisions to the General Plan
Approval and/or General Operating Permit for Natural Gas
Compression and/or Processing Facilities (commonly referred
to as the “GP-5”). Changes to the GP-5 include the removal
of the 100,000 ton-per-year limit on facility greenhouse gas
emissions that can be authorized under the permit and the
addition of an annual compliance certification requirement. The
changes affect new compression and processing facilities seeking
coverage under the GP-5 as well as existing compression and
processing facilities modifying or renewing GP-5 permits. For
more information, contact John Schmelzle at 717.942.1203 or
[email protected]. Z
trenches >>> continued from page 2
perspective >>> continued from page 3
Elena & Clement: Though working towards our PhDs was a very
fulfilling and rewarding experience, once graduated, we knew
we wanted to get out of the lab! And after studying one subject
for years, we are excited to have the opportunity to help solve a
vast array of issues for our clients at Zephyr. Z
determined that the suit is “frivolous, unreasonable or groundless, or that the plaintiff continued to litigate after it clearly
became so.”
Clement Cros and Elena Nirlo
Staff Engineering Associates
Team. Defending a citizen suit in federal district court warrants
a litigation attorney familiar with the local rules and judiciary,
an environmental lawyer that knows the applicable substantive
environmental and regulatory framework, and technical experts
who can assist counsel and provide the necessary expert testimony at trial. Z
Al Axe
Lisa Dyar
Winstead PC
6
FROM THE PRESIDENT
Will Austin Become the Next Chaco Canyon?
I
f you have never visited Chaco Canyon Culture National
Historical Park in northwestern New Mexico, I highly recommend it. Between AD 900 and 1150, Chaco Canyon was a major center of culture for the Ancient Pueblo Peoples. Chacoans
quarried sandstone blocks and hauled timber from great distances, assembling 15 major complexes that remained the largest
buildings in North America until the 19th century. Today Chaco
Canyon is a UNESCO World Heritage Site located in the arid
and sparsely populated Four Corners region. Its sites are considered
sacred ancestral homelands by the Hopi and Pueblo people, who
maintain oral accounts of their historical migration from Chaco
and their spiritual relationship to the land. Walking through the
ruins of Chaco Canyon today is eerie — it’s almost as though
everyone woke up one morning and abandoned their “cities.”
Archaeologists posit that Chaco Canyon culture began unraveling around 1140, possibly due to an extreme 50-year drought
that caused daily living at the scale of Chaco Canyon to become
unsustainable. What looks like an abrupt disappearance to observers nearly 900 years later was probably a slow and painful death
of an entire culture. Refugees may have been absorbed into the
Pueblo and Navajo cultures or simply perished. Anyone still
living in the area during the drought years no doubt experienced
a precarious, water-starved existence.
Today much of America’s South and West are in the grip of
drought. In fact, Texas and the Southwest face a triple threat:
booming population growth, looming drought, and the unpredictable effects of climate change. California has entered its fourth
year of record-breaking drought, and more than half of Texas has
experienced drought for at least five years. Near Austin, although
there has been enough rainfall that the vegetation is deceptively
green, the Highland Lakes, which are the region’s primary water source, are barely one-third full. One of the reasons these
lakes were created was in response to droughts in the first third
of the twentieth century, but a key difference today is that the
population of Austin and the Texas Hill Country and the region’s
demand for water are many times what they were before the
dams were constructed in the 1930s and 1940s.
water rights from the Highland Lakes through 2050. To the south,
San Antonio is furiously pumping groundwater to enable its
similarly torrid rate of growth. However, the water security of
both cities is very much in question if the drought is prolonged.
Similar stories can be told across the Southwest. In Arizona, Utah,
and Nevada, Lakes Powell and Mead on the “other” Colorado
River are in even worse straits. Lake Mead is at its lowest elevation since the lake was filled in the 1930s.
We citizens of the Southwest will need to get smarter about
water conservation, infrastructure design, and public policy, and
we’ll need all the technology at our disposal to secure our water
future. One of Zephyr’s clients is constructing a new manufacturing plant on the Texas Gulf coast and will supply its water needs
by employing reverse osmosis technology on seawater so as not to
consume other scarce water resources. Although such a project is
a novelty in the area now, I don’t doubt we’ll be seeing more such
projects as our water resources continue to come under greater
pressure. Hopefully our efforts will be successful and our descendants 900 years from now won’t be walking through our cities
of the Southwest, wondering “whatever happened to the people
who lived here?” Z
Joe Zupan
President
The City of Austin made a savvy deal with the Lower Colorado
River Authority about 15 years ago, theoretically securing senior
Zephyr is a full-service environmental, health, and safety firm offering consulting, training, and data systems services to clients worldwide. We specialize in air and water quality, waste management and cleanup issues, incident management, natural resources, and workplace and community safety.
Currents is published quarterly by Zephyr Environmental Corporation, is edited by David Cabe of Cabe Environmental Solutions, and designed by Allen Griffith of Eye 4 Design. Current and
past issues of this newsletter are available at our website. For more information about Currents, or to add your name to our subscription list, please email: [email protected] or visit
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coal plants >>> continued from page 1
which an alkaline material (e.g., calcium hydroxide)
is injected into the boiler exhaust upstream or downstream of the air heater. DSI can achieve greater than
80 percent removal of HCl from the boiler exhaust
stream. Additional benefits, such as reductions in
other acid gases (e.g., sulfuric acid), SO2, and condensable particulate matter (PM) emissions, are also
being realized.
As discussed earlier, oxidized Hg can be captured by a
wet scrubber; however, a significant portion of the oxidized Hg can revert to its elemental form in the scrubber slurry. Ultimately, this Hg is re-emitted as a gas from
the scrubber. To address this issue, additives such as activated carbon or sulfides can be injected into the slurry
to lock-up the Hg in a solid or liquid form, which then
exits the scrubber with the slurry discharge.
The use of DSI entails careful consideration of the effect on other regulated pollutants. For example, use of
sorbents that contain carbonates can drive up emissions
of carbon dioxide — a result that could be problematic
if EPA’s proposed Clean Power Plan for reducing power
plant emissions of this greenhouse gas 30 percent by
2030 survives legislative and legal challenges (See July
2014 issue of Currents).
The availability of chemical additive/sorbent injection systems that are relatively inexpensive to purchase and operate should help keep older coal-fired
power plant units in operation and in compliance with
emission standards for the foreseeable future. Many
of these systems are designed to work in tandem with
existing emission controls, such as wet scrubbers and
PM capture equipment, to enhance pollutant control
efficiency. Given their demonstrated feasibility and effectiveness, these systems should continue to evolve,
increasing the number of control options over time. For
example, companies are testing the application of additives at the coal mine. Experience has shown that,
in general, coal additive/sorbent injection systems can
be permitted relatively quickly given the lack of significant air quality issues associated with their use. Z
Another material used for emissions control is activated
carbon. The injection of powdered activated carbon
(PAC) into the boiler exhaust adsorbs Hg in its elemental gaseous form and converts it to an oxidized form that
can be captured by a wet scrubber or by the PM control
equipment. The PAC is commonly conditioned by the
manufacturer with a halogen to enhance its effectiveness, especially for low chloride-content coals. PAC
can reduce Hg emissions by up to 95 percent, depending on the type of coal and emissions control equipment, and whether the PAC has been conditioned
with a halogen.
Lou Corio
Senior Technical Specialist
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