Jnited States
Environmental
Protection Agency
Office of
Research and
Development
EPA 600/9-79-040
October 1979
Energy, Minerals and Industry
&EPA Decision Series
energ
enviro
Proceedings of the
Conference
on the
Interagency
Energy/Environment
R&D Program
entl
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the energy/environment
R&D decision series
Some of the basic problems facing our society today involve the use
of our energy resources and the consequent effects on our environment.
These problems affect everyone, and everyone has an interest in their
resolution. But the technical aspects of these problems make it difficult
for a major portion of the interested public to understand and participate
in the decision-making process. This volume contributes to the bridging of
this information gap.
The Energy/Environment R&D Decision Series was inaugurated late
in 1976. The series presents, in an easily understood and informative
manner, selected key issues and findings of the Federal Interagency
Energy/Environment Research and Development Program, which was
initiated in fiscal year 1975. Planned and coordinated by the Environ-
mental Protection Agency (EPA), the Interagency Program sponsors more
than 1,000 research projects ranging from the analysis of health and
environmental effects of energy systems to the development of pollu-
tion control technologies.
If you have any comments, please write to Francine Sakin Jacoff,
Series Editor, RD-681, US EPA, Washington, DC 20460. This document
is available through the National Technical Information Service, Spring-
field, VA 22161. Mention of trade names and commercial products herein
does not constitute EPA endorsement or recommendation for use.
Symposium and Report Credits:
Conference Coordinator: Kathleen Dixon
Assistant Conference
Coordinators/Associate
Editors:
Conference Support:
Susan Fields
Daryl Kaufman
Peter Mavraganis
Gary Sitek
Robert Spewak
Andrew Trusko
Ann Gerard
Deborah Pierce
Deborah Wade
Editor:
Elinor Jane Voris
Associate Editors: Elizabeth Caldwell
Paula Downey
Diane O'Neill
Art and Design:
Jack Ballestero
Howard Berry, Sr.
Graphic Support: John Feeol
William Hardesty
Charles Runner
Photography: American Petroleum Institute
EPA Documerica
Peter Mavraganis
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energy
environment IV
Proceedings of the
Fourth National Conference
on the
Interagency
Energy/Environment
R&D Program
JUNE 7 & 8 1979
Shoreham Americana Hotel
Washington, DC
SPONSORED BY:
The Office of Energy, Minerals and Industry
Within the Environmental Protection Agency's
Office of Research and Development
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contents
session 1: energy
Introduction «*
Steven R. Reznek, Ph.D. (EPA)
Keynote Address •
The Honorable Max Baucus (U.S. Senate)
Overview on Energy Futures 1 *
Donald M. Kerr, Ph.D. (DOE)
Questions and Answers 17
Environmental and Health Effects Research: 23
The View From DOE
Ruth C. Clusen (DOE)
session 2: environmental regulations
Environmental Regulations: Air 29
Walter C. Barber, Jr. (EPA)
Environmental Regulations: Water 33
Swep T. Davis (EPA)
Impact of the Resource Conservation and Recovery 37
Act on Utility Waste
Steffen Plehn (EPA)
Questions and Answers 41
session 3 control technology
Sulfur Oxides Control: Flue Gas Desulfurization 49
Michael A. Maxwell (EPA) and Michael D. Shapiro (DOE)
Nitrogen Oxides Control 69
George Blair Martin and Joshua S. Bowen, D. Eng. (EPA)
III
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CONTENTS (CONTINUED)
Questions and Answers 101
New Developments in Fine Particle Control 103
James H. Abbott, Leslie E. Sparks, Ph.D., Dale L. Harmon,
and Dennis C. Drehmel, Ph.D. (EPA)
Disposal of Wastes From Coal-fired Power Plants 117
Julian W. Jones (EPA)
Artificial Fishing Reef Construction Using Coal Wastes 131
(film)
U.S. Department of Energy Fluidized-Bed Combustion 135
Program
Steven I. Freedman, Ph.D., and William T. Harvey (DOE)
Control Technology Panel Discussion With Questions 147
and Answers
Frank T. Princiotta (EPA), Michael D. Shapiro (DOE),
H. William Elder (TVA), and
B. G. McKinney, Ph.D. (EPRI)
Questions and Answers
155
session 4: energy and the ocean environment
The AMOCO CADIZ Oil Spill 161
Wilmot N. Hess, Ph.D. (NOAA/ERL)
Effects of Chemicals Used in Oil and Gas 171
Well-Drilling Operations in Aquatic Environments
Norman L. Richards, Ph.D. (EPA)
Questions and Answers 183
session 5: atmospheric transformation and transport
Satellite Observations of Persistent Elevated Pollution 189
Episodes (PEPE)
Walter A. Lyons, Ph.D. (MESOMET, Inc.)
Status Report on Project VISTTA 211
William E. Wilson, Jr., Ph.D. (EPA)
Environmental Effects of Acid Precipitation 223
Norman R. Glass, Ph.D., Gary E. Glass, Ph.D. (EPA),
and Peter J. Rennie, Ph.D. (Canadian Forestry Service)
IV
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CONTENTS (CONTINUED)
Air Quality Studies in Support of the Ohio River 233
Basin Energy Study (ORBES)
Michael T. Mills, Ph.D. (Teknekron Research, Inc.)
and Lowell F. Smith, Ph.D. (EPA)
Questions and Answers 247
session 6: health effects research
Assessment of the Carcinogenic Risk From Energy-Related 251
Organics
J. Michael Holland, William M. Eisenhower,
Larry C. Gipson, Lawton H. Smith, Thomas J. Stephens,
and Mary S. Whitaker
(Oak Ridge National Laboratory)
Health Consequences of Nitrogen Dioxide Exposure 261
Donald E. Gardner, Ph.D., Judith A. Graham, Ph.D. (EPA),
and Daniel Menzel, Ph.D. (Duke University)
Health Effects Panel Discussion 295
Elizabeth Anderson, Ph.D., Roy E. Albert, Ph.D. (EPA),
Richard Bates, Ph.D. (NIH), Jean French, Dr. PH (HEW),
and Cyril L Comar, Ph.D. (EPRI)
Questions and Answers 301
The Department of Energy's Diesel Research Program 305
Tom J. Alexander (DOE)
Automotive Diesel Panel Discussion 315
Roger Cortesi, Ph.D. (EPA), Richard L. Strombotne,
Ph.D. (DOT), Tom J. Alexander (DOE),
and Charles Gray (EPA)
Questions and Answers 321
participants' index 327
federal agency acronyms 330
v
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nerg
* l
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NATIONAL CONFERENCE
ON THE INTERAGENCY
ENERGY ENVIRONMENT
PROGRAM
INTRODUCTION
Steven R. Reznek, Ph.D.
Office of Environmental Engineering and Technology
U.S. Environmental Protection Agency
CONFRONTING
LIMITATIONS
In December, 1973, the Arab oil embargo forced the people of the
United States to confront the consequences of critically limited natural
resources. We continue to experience these consequences, and increasingly to appre-
ciate the resultant economic, political, environmental and social difficulties.
Since the initial OPEC price rise in the winter of 1974, we have experienced a
wintertime natural gas shortage, an extremely serious upset at Three Mile Island, a
prolonged suspension of Iranian oil production, and a continuing escalation of the
price of petroleum. These events have proved so perplexing that we do not yet have a
clear understanding of where our actual energy choices lie, or what the implications
of those choices will be for the future of our economy, environment, and indeed all of
society. Furthermore, we have been unable to translate what knowledge we do have
into terms that will lead to public acceptance and ratification as national policy.
CONFRONTING
TRADITIONAL FAITH
During the 30 years between the Second World War and the OPEC oil embargo
certain lessons were demonstrated and redemonstrated until they were accepted
without question. We learned that technological development was not just desirable or
rewarding, but was absolutely essential for survival in a world of economically and
politically aggressive nations committed to the full exploitation of technology. We
learned that fiscal and monetary policy could control the behavior of our economy.
We learned, or thought we learned, that technological innovation coupled with eco-
nomic policies to ensure appropriate allocations of labor and capital could sustain
natural resource development and economic growth without bounds.
The first resources to be scarce were those that were priced the lowest—clean air
and clean water. The next—energy—was also priced far too low. Now, to confront
these problems of polluted water and air and shortages of energy, we must first
confront our traditional faith in technology, fiscal and monetary policies, and the
limitlessness of natural resources.
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A FUNDAMENTAL
REALITY
For many years the cost of energy decreased. In the first 74 years of this
century, our investments of capital and labor returned increasing amounts of useful
energy in the form of electricity, home heat, and transporation fuel. The decreasing
cost stemmed in part from expanded discoveries of sources of easily obtainable fuel,
in part from technological innovation, and in part from investments in the production
and transportation equipment capital necessary to make energy delivery efficient.
Today, the cost of new energy sources is increasing, and we face an entirely
different prospect. Future investments of capital and labor will return less energy
than before. In the past an hour's labor, properly divided among exploration, building
capital equipment, and operating drilling rigs, would return one barrel of oil. Today,
an hour's labor properly divided between building and using mining machines will
produce coal with an energy content equal to about one quarter of a barrel of oil.
Simply stated, we are going to use increasing amounts of our productive capacity to
obtain decreasing amounts of energy. The challenge will be to make investment in
these high-cost/low-yield technologies attractive.
This situation has created remarkably difficult problems for our economic and
social systems. As a society, we have found it enormously difficult to accept the fact
that inexpensive fuels are disappearing and that we must now not only pay more, but
use less. Foreign or domestic oil interests may exploit this situation to realize large
profits, but this does not deny the fundamental reality-we will have to pay more and
we must use less. We must change from a society oriented to resource exploitation
to one oriented to resource conservation.
HARMFUL AND
BENIGN SOURCES
The cost of the new sources of energy will be paid in part economically and in
part in terms of environmental quality and occupational or public health. Both coal
and nuclear power can cause widespread degradation of environmental quality and
human health. Coal mining, particularly underground mining, is a dangerous occupa-
tion. Coal production can cause widespread land and hydrological disturbance. Coal
combustion can generate increased air pollution. When compared with oil and gas
production, the increased use of coal will accelerate the deterioration of clean air,
water and productive land.
Many of the adverse impacts on health and environmental quality can be con-
trolled or avoided. Most mined land can be reclaimed. Particulate matter and the
oxides of nitrogen and sulfur can be scrubbed from flue gas. Acid precipitation
and its effects on agricultural and forest production can be reduced.
Controlling these pollutants increases the monetary cost of energy, but failure to
control them lowers the productivity of land resources and imperils the health of our
population. We can elect to pay the environmental and public health costs of using
coal now with reclamation practices and flue gas cleaning technology, or, they can be
paid later with barren lands and premature deaths.
Most new sources of fossil energy, e.g., oil from the Artie or the Outer Con-
tinental Shelf, coal burned directly or processed to synthetic liquid or gaseous fuels,
and oil shale, potentially threaten environmental quality. Other new energy sources
such as unconventional natural gas, geo- or oceanic thermal gradients, biomass-derived
fuels and solar energy seem environmentally benign. The vastness of the scale on
which energy supplies will be used, however, dictates a careful and thoughtful evalua-
tion to ensure that these sources are, in fact, developed using materials and practices
that do not create environmental or public health problems.
In addition to the problems of mine drainage, disturbed land, and air pollution,
coal use presents two as yet unresolved environmental questions. Mining, conventional
combustion, coal processing and pollution controls all generate large volumes of solid
wastes. At present too little is known about how these wastes should be handled to
prevent serious future problems. We know that partial and complete combustion will
form or concentrate metallic and organic pollutants in ashes and sludges. However, we
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ADDITIONAL ENERGY-
RELATED CONCERNS
ENERGY/
ENVIRONMENT
do not know the geo-chemical behavior of these materials. Processing operations
require incomplete combustion and will generate pollutants that may have carcinogenic
or other chronic health effects. If coal is to be the future source of liquid or gaseous
fuels, we must develop a much improved understanding of health risks from the new
pollutants that will be generated.
The conversion of our automotive fleet to diesels would save energy, but diesel
soot contains many of the complex organic materials that are known to cause cancer
or other chronic health problems. Offshore and Arctic petroleum development intro-
duces contaminants into particularly fragile environments. Materials such as drilling
mud biocides, geological fluids and spilled oil degrade ecosystems that are vulnerable
and slow to recover. Oil shale development poses environmental problems similar to
those of coal including the requirements for large quantities of water. Perhaps the
ultimate limit on fossil fuel use will be caused by the accumulation of CO2 in the
atmosphere. A doubling of the concentration of carbon dioxide may result in climatic
changes. Expanded use of coal and oil shale could produce these changes in the
beginning of the next century.
The reality of diminishing supplies of petroleum and natural gas will change our
society. The rate of change and the future form of society will be determined by the
choices we make now. One of those choices will be how to apportion the costs
between pollution controls and environmental impacts. Of late, a note has crept into
energy discussions that is contrary to good decisionmaking and responsible public
policy. Environmental concerns are being unfairly blamed for blocking energy develop-
ment, when in actuality the problem appears to lie in the uncertainties of investment.
For example, discussions in the press of the Tellico Dam decision, the Sohio pipeline,
and the New Source Performance Standard for coal combustion have been less than
comprehensive or well-informed and have failed to report all the economic and envi-
ronmental considerations.
The Interagency Energy/Environment R&D Program was designed to provide for
the exchange of information needed for knowledgable decisionmaking. At this, the
Fourth National Conference on the Interagency Energy/Environment R&D Program,
we will explore our present understanding of many of the issues concerning the use of
our remaining supplies of nonnuclear fuels. The purpose pf the conference is to
provide the information necessary for making better choices between meeting control
costs now and paying for impacts in the future. Research will generate the knowledge
needed for decisionmaking. Proper discussion of the available knowledge in forums
such as this will lead to unprejudiced decisions that best serve the public interest.
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- I
The Honorable Max Baucus
KEYNOTE ADDRESS
The Honorable Max Baucus
United States Senator From Montana
REEXAMINE AND REDEFINE
A NEW CONSCIOUSNESS
Thank you for your warm welcome.
When asked to speak at this conference, I realized that there are no two words
whose meaning has changed more in the past decade than energy and environment. As
I prepared for this speech, I was forced to reexamine and redefine what these words
mean.
Growing up in Montana, I felt the pride in the out-of-doors that most Montanans
feel. I could walk to a stream, bend down, and drink the water as it flowed by. I
remember herds of deer and elk in the valleys right near my parents' ranch outside
Helena. And, of course, I was never more than 15 minutes from a good trout stream.
Today there is a new consciousness in Montana. The President's decision to
decontrol the price of old oil means that previously marginal oil reserves now become
productive, and rigs are springing up all over the state.
Eastern Montana's plains contain some of the world's richest deposits of
strippable coal, and massive equipment is peeling away much of the land. How will
development of these resources, so vital in our national energy picture, affect the
countryside of my state? That's the question many Montanans are asking.
Not everyone is as lucky as I have been. Not everyone enjoys tromping through a
mountain valley where the only other creatures are the birds and animals who live
there. What happens, though, when some geologist discovers oil in that mountain valley
and the hills are dotted with drilling rigs and the streams become filled with drilling
wastes? Is that oil worth the destruction to the valley? What price are we willing to
pay for energy? These are the central questions we must ask ourselves. These are the
questions that perhaps more than our supply of gasoline will determine how enjoyable
our lives are in 5, 10, 25 and 50 years.
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HORROR STORIES
AVAILABLE LEGAL TOOLS
INVESTIGATIVE STRIKE
FORCE
If we have learned anything in recent years about increasing energy production,
it's that we must not develop energy resources without fully considering the risks they
may cause to our environment. Whether it is nuclear waste from Three Mile Island,
waste from oil drilling rigs, or sludge from coal, we have learned that lesson the hard
way. There is waste material produced from producing energy, that's for sure. As more
and more energy is consumed to produce more and more products, more and more
toxic waste is produced.
You all know the horror stories: radiation leakage at Three Mile Island, PCB's
strewn along North Carolina roadsides, Love Canal, and on and on. American industry
generates about 100 billion pounds of hazardous wastes every year. That is about the
total weight of every car now on the road. But only 10 percent of those wastes are
disposed of properly. The rest are buried somewhere threatening to poison the water we
drink, the air we breathe, the food we eat. It's a time bomb just waiting to go off. No
one knows where or when that's going to happen. I don't think I'm telling you any-
thing you don't already know. Nor do I believe you are willfully ignoring the import-
ance of our problem. But that doesn't alter my conclusion: The Federal Government
does not have a comprehensive, aggressive strategy to defuse that bomb.
We don't need new legislation. The Safe Drinking Water Act, the Toxic Sub-
stances Control Act, the Clean Water Act, and the Clean Air Act were enacted in
response to growing evidence that we were polluting our environment. There are 21
Federal statutes to combat the hazards of toxic waste from uranium mill tailings to
lead-based paint, and criminal penalties are prescribed for violators of these acts when
they engage in conspiracy or fraud. We don't need new laws. We must simply enforce
the laws already on the books. Legal tools are available. They are not being used. The
financial incentive to dump toxic wastes is high, but the risk of prosecution is not.
Why aren't these tools being used? In April, I chaired a hearing to look into that
question. We found that the Justice Department has only one full-time attorney to
prosecute hazardous waste cases. That's not just the Hooker Chemical/Love Canal
case—that's all hazardous waste cases. Hooker Chemical, on the other hand, has hired
three law firms for its defense against the government. I don't think the Federal
Government and the people of the United States have much chance against those
odds. It's a little like Calvin Murphy trying to guard Wes Unseld, Bobby Dandridge,
and Elvin Hayes at the same time. The Government's litigation staff is pitifully
inadequate.
The problem is compounded by EPA's delay in promulgating regulations under
the Resource Conservation and Recovery Act of 1976. The regulations under this
act—potentially the most powerful weapon in the battle—will not be completed until
December of this year, more than a year-and-a-half late. These regulations will, of
course, be subject to court challenges. To survive any challenge they must be in accord
with Congressional intent. We can't afford to have the regulations thrown out com-
pletely, as in the case of the Clean Water Act.
Nevertheless, there are a few things we can do. First, the key to any successful
prosecution is thorough, competent investigation. Polluters and dumpers won't be
deterred unless the government wins the cases in court. But, incredibly, EPA has yet to
hire a single investigator with law enforcement training. That's an institutional failure
of massive proportions. EPA estimates there are over 2,000 hazardous waste dumps
across the United States that pose an imminent and substantial danger to public health.
With a threat that large, EPA desperately needs an investigative strike force, and their
training should be comparable to that given FBI or IRS agents. Investigators should be
capable of identifying hazardous waste dumps, tracking down the owners, or former
owners, and establishing whether organized crime is involved.
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LAW ENFORCEMENT ETHIC
COORDINATION OF
FEDERAL AGENCIES
HAZARDOUS WASTE
HOTLINE
THE STAKES ARE HIGH
Second, the strike force should be guided by a professional law enforcement
ethic. To me that means a commitment to tough, uncompromising investigations-a
willingness to follow through until the job is done. It's an attitude that must be
established at the beginning. All too often the Federal Government is willing to settle
cases out of court—to negotiate a civil remedy when criminal sanctions are clearly
called for. EPA and the Justice Department must demonstrate that they are willing to
go to the mat on these cases. It's time to serve notice that the law enforcement
agencies of this government are determined to prosecute to the fullest extent of the
law those who willfully violate our country's antipollution statutes. The only way to
defuse a time bomb is to have the courage and resources to take the bold steps neces-
sary. The battle against environmental terrorism cannot be fought with timidity or a
strategy of compromise.
Third, coordination is a crucial factor in any effective law enforcement program.
Several agencies of the Federal Government already are involved in different aspects
of waste management. For example, the Bureau of Alcohol, Tobacco, and Firearms
has jurisdiction to investigate hazardous wastes wherever there is a threat of explosion.
That's the case in Elizabeth, New Jersey, where a warehouse is filled with corroded
drums that are leaking toxic chemicals. Who knows how many people might be injured
or killed? Sites posing this kind of threat should be identified immediately and the
Bureau of Alcohol, Tobacco, and Firearms should be called in to investigate wherever
its jurisdiction warrants. Moreover, the Department of Transportation's Bureau of
Hazardous Materials Transportation should be called in wherever its jurisdiction
warrants.
In addition, greater cooperation with all the states should be encouraged. State
highway patrols could monitor roadside dumping of hazardous wastes. Local health
officials could monitor toxicity levels in the local water supply and report their
findings to EPA. I would also like to point out that each citizen has a role to play in
the enforcement of pollution control. It should be remembered that the successful
prosecution of those responsible for dumping thousands of gallons of PCB's along
North Carolina highways was initiated by one alert, concerned citizen.
Perhaps the EPA and the Justice Department should establish a hazardous waste
hotline so that citizens can alert the government to surreptitious dumping and provide
evidence of illegal waste management practices. The American people have every right
to expect that our nation's laws controlling pollution and waste will be vigorously
enforced and I am convinced they, too, will play their part in this crucial effort. We
must remember, regulations are only part of the answer. We must clean up the present
regulatory process. Too often delays caused by a cumbersome bureaucracy thwart
efforts to enforce the law.
The stakes are high. Each generation of Americans becomes the custodian of our
natural resources. Each generation, in turn, has the obligation to pass this inheritance
on to future generations. Is Montana going to lose its pristine valleys and trout streams
before my son is old enough to enjoy them? Or, will we strike a balance where these
invaluable and irreplaceable resources are protected? Finding that balance and being
willing to act with courage and fairness is our challenge.
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Donald M Kerr Ph D
OVERVIEW ON ENERGY FUTURES
Donald M. Kerr, Ph.D.
U.S. Department of Energy
SERIOUS DEBATE
OIL IMPORTS
Since the oil embargo of 1973, the American people have engaged in an in-
creasingly serious debate over oil supply and prices. Our standards of living have
been called into question as world oil prices have risen and relative world supplies
have either decreased or remained stagnant. There is an emerging consensus that we
must reduce our oil import bill which is draining over $50 billion a year from our
economy. What we do not have, however, is a consensus of how we should go about
this task. The President's National Energy Plan sets two cornerstones upon which we
can build toward this goal. The first is conservation and the second, to which I will
address myself, is the increased usage of coal and other alternative energy sources.
Given the meager prospects for impovement in world oil supply and the long
leadtimes for the introduction of other alternatives, the United States will require
much greater use of coal in order to grapple effectively with the energy problems of
the 1980's and 1990's. Without greatly expanded use of coal, this country just may
not make it. In the abstract, the need to increase coal production and use is recognized
by all. In practice, countless decisions, arrived at independently by various levels of
government, tend to militate against the use of coal. If this Nation is to cope effec-
tively with economic and national security problems during the rest of this century,
the obstacles to increased coal production and use must be removed by an effective
national commitment to coal.
Two years ago the President presented the National Energy Plan (NEP) to the
American public and to Congress. The NEP proposed measures that would keep oil
imports at 6 to 7 million barrels per day (MMBD) in 1985. While many of these
measures were enacted, three elements critical to greatly increased coal use have not
been implemented:
• Domestic oil and gas prices have not moved rapidly to world levels.
• An industrial user's tax and rebate mechanism, reinforced by a regulatory pro-
gram, was not enacted.
• A stable regulatory regime has not been established.
11
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SOMBER ASSESSMENT
LESS OIL IN THE 1980'S
LAGGING COAL GROWTH
As a result of these and other factors, the use of coal in 1985 is expected to be
substantially less than projected earlier and the demand for imported oil higher by at
least 2 MMBD. At the same time, developments in the world oil market have made
it increasingly doubtful that an additional 2 to 3 MMBD will be available.
The extended curtailment of Iranian exports and the reduced level at which
production was resumed have brought closer the time when world oil demand exceeds
availabe supply. There have been no other developments that have favorable oil supply
implications for the near- or long-term. This more somber assessment of world oil
prospects is based on the following considerations:
• The situation in Iran has not stabilized and current exports of 2 to 3 MMBD
could be stopped again at any time.
• Saudi Arabia has delayed capacity expansion and has imposed restrictions on
production.
• Elsewhere in OPEC, no additions to capacity can be anticipated and current
capacity continues to erode due to maintenance difficulties and maturing fields.
• The disappearance of spare capacity makes the U.S. more vulnerable to random
disturbances in the intricate global oil supply system. The Nation is also more
vulnerable to politically-inspired embargoes, imposed by any one of several
small producers, that would have been little more than an inconvenience a few
years ago.
• Outside of OPEC, no new oil provinces have been discovered, despite continued
drilling, to supplement the last large finds in the North Sea, North Slope, and
Mexico; and there is no improvement in the energy outlook for the Soviet
Union.
• The position of the price moderates in OPEC has been weakened by the change
in Iran and the successful demonstration that less oil brings more money.
Consequently, there will be even less oil in the 1980's than was expected 2 years
ago and quite possibly no more than is available today. If additional oil is not avail-
able, increased demand will push world oil prices up causing higher rates of inflation
and reducing output and employment. Under these circumstances, further increases in
U.S. oil imports could be obtained only by bidding available supplies away from
Europe, Japan, and the less developed countries. If further increases in oil imports are
not available on acceptable terms, our Nation will have to meet its additional energy
needs from domestic resources. Although conservation has reduced growth in energy
demand to half the rate of GNP growth, there is still a great demand that must be met
by domestic production. Domestic oil and gas output cannot be expected to increase
sufficiently, even with greater investment. The use of solar and renewable energy
resources will increase steadily in coming years, but long leadtimes in developing and
placing these new technologies in commercial use will push their main contribution
into the next century. Finally, increases from nuclear power may be reduced as a
result of Three Mile Island. The only conclusion that can be drawn is that coal must
play the major role in meeting the Nation's incremental energy needs for the rest of
this century. The alternative is no longer imported oil because it will not be available.
The only other alternative is a permanent slowdown of the economy.
Notwithstanding the critical need for coal, growth in domestic coal use is lagging.
To meet the Nation's energy needs, coal consumption will have to have risen from 623
million tons in 1978 to 1.0 billion tons by 1985 and 1.6 to 2.1 billion tons by 2000,
depending on the contribution of nuclear power. This will require at least a 4.5%
annual increase in coal use. Yet, over the last 5 years, annual growth has averaged
2%, and has even been less in recent years. The difference between a 2% and 4.5%
annual rate of growth in coal use by the year 2000 is approximately 600 million tons
of coal or the equivalent of 6 million barrels of imported oil per day. Additional oil in
that quantity is not likely to be available. Two major factors will determine how
12
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ECONOMICS
ECONOMIC INCENTIVES
ADVANCED
ENVIRONMENTAL CONTROLS
quickly and to what extent we may make use of our abundant coal supplies. The first
is economics; the second; environmental regulations and technology.
In terms of economics, the critical factors will be the relative cost of synthetic
fuels produced by coal and future world oil prices. The current world market price for
oil is approximately $16-$17/barrel. The current estimated cost of synthetic fuels from
coal ranges from $23-$35/barrel. Therefore, although the economics today do not
seem to make sense, viewed in the perspective of unpredictable rises in world oil prices
and the leadtimes needed to construct and put on-line synthetic plants, the critical
decision time for the U.S. is now. The economics of alternative energy sources such as
synthetic fuels from coal and alcohol fuels cannot be judged on a strict dollar-for-
dollar basis with world oil prices. We must also look at the drain on our domestic
economic resources which our huge oil import bill causes. We must ask ourselves the
question: Is $17 a barrel paid abroad really cheaper than $23 a barrel paid into the
U.S. economy?
Until the year 2000, close to 90% of all the coal consumed in this country
will be burned directly. Therefore, a primary objective of our national coal program is
to ensure that environmentally sound technologies are available to allow us to burn
this coal. The economics of liquefaction technologies are issues which must be resolved
in the 5- to 10-year period to come. An immediate hindrance to the increased usage of
coal must be addressed if we are to build upon the cornerstone which the NEP has
laid.
There is an unavoidable conflict and a need to balance the necessary increased
usage of coal with air quality. If the Nation is to have reliable sources of power,
then hard decisions must be made. The environmental control technologies which
we are pursuing can help to alleviate much of the conflict but the State and Federal
Governments must realize that in the short term, technology is not the total answer.
The balance between increased coal usage and environmental integrity is not one which
can be struck entirely at the national level. In many cases, individual states have passed
air quality control standards more stringent than the national ambient air quality
standards. Some thought must be given to relaxing these standards if increased coal
usage is to be achieved.
We must also consider economic incentives and depreciation allowances in order
to promote the usage of coal as a boiler fuel in existing facilities. In a similar vein,
the Federal Government must seek to streamline licensing procedures for coal-fired
utility and industrial users of coal.
There is a limit to what the Department of Energy can do by itself. We can seek
to speed up the licensing of such plants; to increase coal production; and to improve
technologies such as atmospheric fluidized bed combustion and advanced control
technologies, but other elements of the Federal government, such as the Environmental
Protection Agency, the Department of Transportation and the Department of Interior,
also have significant roles to play if we are to obtain our goals of increased coal
utilization.
Three methods of removing pollutants from coal exist:
• Coal cleanup (examples are chemical and physical preparation)
• Combustion techniques (examples are atmospheric and pressurized fluidized bed,
and MHD)
• Flue gas or gas stream cleanup (key areas addressed in environmental control
technology program)
In order for these systems to become commercially practical, careful control must be
maintained of the type and amounts of impurities in the gas which can be accepted
without undue corrosion, erosion, and/or contamination of system components.
Requirements in this area may, in fact, be more severe than EPA emission standards,
13
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CLEANUP SYSTEMS
FLUE GAS
DESULFURIZATION
FLUE GAS CLEANUP
especially in the area of participates. DOE's funding for this area increases from $2.4
million in FY 1979 to a request of $10.4 million in FY 1980.
Efforts are oriented primarily toward turbine cleanup systems and molten car-
bonate fuel cell cleanup systems. Both hot low-Btu gasifier/gas turbine and pres-
surized fluidized bed/gas turbine systems will be studied. The aerodynamics/materials
problems linked to the high-speed turbomachinery do not exist with the fuel cell;
however, the molten carbonate fuel cell is susceptible to catalyst poisoning, electrode
damage, and electrolyte contamination.
Flue gas cleanup and gas stream cleanup, along with technology support, bring
the total budget request for FY 1980 to over $43 million, a 600% increase over the
1979 amount-the largest growth in the FY 1980 DOE budget. Since improvements in
flue-gas cleanup technology can have an immediate application commercially, DOE has
accelerated its program in this area. Funding has been boosted from $2.7 million in
fiscal 1979 to a request of over $25 million in fiscal 1980.
Efforts are concentrated in three areas:
• Advanced flue gas desulfurization
• Advanced flue gas cleanup
• Lime/limestone scrubber reliability
Advanced flue gas desulfurization projects will evaluate a number of potential
processes, many of which are sufficiently developed to permit a narrowing of choices
for application in early 1982 through 1985:
• One of the advanced scrubber technologies incorporates scrubbing the flue gas
with a solution quite similar to conventional lime/limestone slurries, but then
regenerating the scrubbing solution rather than discarding it as a sludge. The
primary by-product is sulfur dioxide, which can be converted into sulfuric acid
or elemental sulfur. Capital costs of the more complex process are generally
higher, but operating costs potentially can be reduced if the sulfur by-products
can be sold.
• Systems using a dry material to absorb the sulfur pollutants from coal burning
are also showing promise. Candidate materials include limestone, nacholite (a
natural sodium bicarbonate), trona (a natural hydrous sodium carbonate), and
high alkali fly ash. These processes produce a dry solid waste with no sludge
disposal problems.
• A third process uses a clear liquid, usually a sodium-based solute, to remove
the sulfur dioxide. By adding lime or limestone to the liquid after it has been
in contact with the combustion gases, the sulfur can be removed as calcium
sulfate, a relatively benign substance which can be used as a landfill material,
as a soil conditioner, or in building materials.
Advanced flue gas cleanup includes methods of removing or minimizing nitrogen
oxides, along with particulates and trace metals. Primary focus is on developing
advanced centrifuge methods, filters, and electrostatic precipitators based on conven-
tional systems. An activity is also being conducted to evaluate new ideas for removing
sulfur from hot gases, including the use of irradiation techniques using electron beams,
lasers, or plasma-jets. Currently about 40 utility-size flue-gas cleanup facilities are
operating in the U.S. and about 100 more are being built or designed.
Combined-cycle generating plants powered by high-temperature, low-Btu gases
from direct coal gasification or high-temperature gases from pressurized fluidized
bed combustion may prove to be an extremely attractive approach for large-scale coal
use.
14
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WET SCRUBBING
RENEWED
COMMITMENT
The most widespread application of flue gas cleaning is wet scrubbing. A water
slurry of lime or limestone is brought into direct contact with the combustion gases,
typically in a spray tower or similar device. Sulfur is removed mainly as calcium sulfite
and in the form of a wet sludge. Sludge disposal costs represent up to 20% of the
capital and operating costs of a flue gas desulfurization system. Sludge is difficult to
concentrate and solidify and requires large amounts of land and careful management to
avoid soil and water pollution. Methods of chemically treating the sludge to produce
suitable landfill material are often prohibitively expensive, and there are doubts about
their long-term effectiveness in cool climates.
The strategy in improving lime/limestone scrubbing reliability is, first, to
collect, correlate, and evaluate detailed experience and then conduct parallel
experimental programs using eastern and western coals. Three 10-megawatt scrubbers at
the Tennessee Valley Authority's Shawnee facility in Kentucky will be used to support
eventual field tests of equipment to increase reliability.
The President has stated clearly and bluntly that the Nation's energy problems
are serious and getting worse. To help solve those problems, it is imperative that
the United States stop using so much petroleum and start using more abundant fuels.
Although the contribution of nuclear power, solar energy, and renewables will be
helpful, the greater use of coal is indispensable. If this Nation can overcome the
unintended obstacles to greater coal use, then the prospects for our security and
well-being are reasonably good. The time is right for a renewed commitment to coal.
15
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&
answers
Joseph D. Martinez
Institute for Environmental Studies
Louisiana State University
S. Thomas Bond
Concerned Land and Natural Resources Owners, Inc.
Peter H. Debes
College of Environmental Science and Forestry
Syracuse University
Barbara Johnson, Ph.D.
City University of New York
Richard Wood
Niagara Mohawk Power Corporation
Jack Corbett
Interfaith Coalition on Energy
QUESTION
Regardless of public concern about nuclear energy,
it seems courageous to face the energy problem head on
and expand nuclear energy as well as coal, recognizing
that it is in many ways more environmentally acceptable
than coal and is a workable technology. In view of the
urgency for energy, how can the administration continue
to place nuclear energy in the same category with solar
energy, which is some distance in the future?
RESPONSE: Dr. Donald M. Kerr (DOE)
The Department of Energy (DOE) is pursuing
nuclear as one of many alternatives for the future.
Nuclear technology that could be deployed now has
already been developed. In fact, there are reactor vendors
in the private sector and the Nuclear Regulatory Com-
mission is available to license power stations as they are
built. We, therefore, are not investing R&D funds in the
present commercial versions of light water reactors, other
than in some generic studies in three specific areas: (1)
more efficient utilization of uranium within those reactors
to make the cost of power less and reduce the require-
ment for uranium, (2) improvement of light water reactor
safety, and (3) design improvements to reduce radiation
exposure for workers in the nuclear industry. Under our
congressional mandate, we are, of course, continuing to
17
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develop an advanced breeder reactor. The point is that
incremental increase in the energy supply will come
through deployment of coal technologies in the near-term
because we can build those plants faster than we can
build new nuclear generating capacity. We do believe,
however, that it is important to maintain the nuclear
generating capacity now in place and also under construc-
tion because we don't have any alternative to it at the
present time.
QUESTION
A good article about Mexican oil appeared in
Science magazine in the fall of 1978 and another in
Current History last February. Dr. Maki, whose area is
economics and international law, assumes that Mexican oil
reserves are roughly equivalent to the reserves in Saudi
Arabia. He says that the discovery of enormous amounts
of crude oil and natural gas in southeastern Mexico raises
the possibility that, for at least the next 20 years, the
United States can simultaneously reduce its consumption
of insecure oil imports and cut back sharply on the size
and intensity of its commitment to perfecting either or
both of its alternate energy options, nuclear and coal. Is
Dr. Maki that far off, or is this something which is
coming up and may have greater importance in the future
than we now realize?
RESPONSE: Dr. Kerr
As I am responsible for energy technology, I can't
comment responsibly about the amount of Mexican oil.
The geologists and those doing the drilling in Mexican
reservoirs will know best whether it is there, and pro-
duceable. As there are uncertainties about both the
supply of Mexican oil and, more importantly, the
Mexican Government's willingness to make it available to
the United States, I believe there is in no way a lessened
need for us to develop domestic alternative sources. You
might write to DOE's Assistant Secretary for International
Affairs for a statement concerning the position of the
Department on this subject.
QUESTION
We have heard about the need for utilization of
coal but no mention of conservation as a principal means
of reducing the urgency of the situation. It would seem
that conservation might provide one of the largest single
ways of meeting the emergency and yet in our study of
the conservation education program of DOE last semester,
we found that it was woefully inadequate, almost nonex-
istent. Would you comment on the Department's position
concerning conservation?
RESPONSE: Dr. Kerr
Although I primarily emphasized the need for
alternative energy supplies this morning, DOE stresses
conservation. These are the two cornerstones of the
National Energy Plan. It is through implementation
-------
by industry, in particular, and not necessarily by DOE,
that the one-to-one relationship between energy supply
growth and GNP growth has changed so that increments
of roughly one half are now involved. We have an Assist-
ant Secretary for Conservation and Solar Applications to
effectively communicate a conservation ethic and imple-
ment it in terms of new plants, new industrial processes,
and particularly in new ways of living our private lives,
which is very difficult. Many dedicated people in the
Department support conservation as the nearest-term
energy supply.
QUESTION
Is all of the Federal support for research and
development for energy done through DOE?
RESPONSE: Dr. Kerr
The majority is, although other departments fund
programs. NASA, for example, has direct appropriated
funds for energy research, the National Science Founda-
tion conducts basic and exploratory work, and the
Environmental Protection Agency (EPA) and the Depart-
ment of Interior are also active in the energy field. The
Department of Transportation is pushing hard for
improved efficiency in automobiles and transportation
systems. Furthermore, many states have invested their
own funds in energy research and development and
frequently we are able to enter into partnership with
them on particular projects. Although DOE is the domi-
nant Federal agency involved, there are many others
participating as well.
QUESTION
Is there an available source that gives a comprehen-
sive picture of the financial investment of the Federal
Government in the various energy fields, such as solar and
wind, and other energy R&D investments?
RESPONSE: Dr. Kerr
When our fiscal 1980 budget was presented to
Congress, there was a briefing sent with it. It attempted
to aggregate not only the DOE-proposed investments, but
those of some other agencies as well. With respect to
solar, for example, there is a direct investment in R&D
but in addition, there are tax credits that have been made
available that must be considered in coming up with the
total Federal investment which presently approximates $1
billion.
QUESTION
Dr. Kerr, your summary of utilization targets and
control technology ideas for increased coal utilization
seemed to focus mainly on the electric power sector.
Would you comment on coal utilization and control
technology targets for what may be the more critical oil-
using sectors of transportation, space, and process
heating?
19
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RESPONSE: Dr. Kerr
One reason the Department is pushing very hard to
develop synthetic fuels from coal is to serve those other
market sectors. We are working on direct usage of coal
for industrial process heat applications, but a greater need
is to displace imported petroleum in the middle distillate
and ultimately in the gasoline markets. To that end, we
have solvent refined coal pilot plants under construction.
Plants such as the Exxon solvent plant and the H coal
plant in Kentucky should not be viewed as synthetic
gasoline plants, as they produce a wide range of products
such as a material equivalent to residual oil. In the pilot
plants, we are investigating ways to alter the slate of
products and to maximize those in the middle distillate
region.
QUESTION
We have a strong conservation program in the
churches and the synagogues comprising the Interfaith
Coalition on Energy. Some of us in the Coalition are
particularly concerned that DOE and, for that matter,
even EPA have not taken a serious look at the coal
reactors that are based on blast furnace technology.
Enclosing blast furnaces helped clean up the city of
Pittsburgh, which demonstrates the value of the technol-
ogy. The reactor burns the lowest-grade, high-sulfur coal
in an enclosed system, producing heat, steam, and elec-
trical generation in the daytime and at night a gase-
ous fuel to be stored or distributed. There is no smoke
stack to spew out sulfur-bearing compounds. The residue
is not an ash to be dumped but a slag to be used for such
things as construction material, cinder blocks, paving
streets, or possibly encapsulation of noxious wastes
such as those at Love Canal. DOE talks about scrubbers
and cleaning up flues, when there has been a system
before them for 2 years that doesn't have a flue, doesn't
need scrubbers, and doesn't require the disposal of ashes.
Why hasn't the proposal for this proven system been
addressed by DOE?
RESPONSE: Dr. Kerr
You have described a pyrolysis system. One
attractive aspects about this system is that although it
does yield heat and consequently steam, and environ-
mental emissions can be controlled, it doesn't do what
is most needed right now in terms of entering, for
example, the distillate market. Hydrogen has to be added
to coal to get better fuels. A totally enclosed plant very
similar to what you have just described and in which
hydrogen is added to the coal will give a mixture of
products that includes liquids and clean solids. If the next
phase of the plant is properly equipped, the sulfur can be
precipitated out and the end product will be a slag.
There is no question that there are attractive, totally
enclosed processes that would reduce emissions. The
reason for focusing on flue gas cleanup and the like is to
find ways to use existing installed plant capacity. As we
become able to afford new plant capacity we will look to
some of these advanced methods.
20
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COMMENTS
There are those of us who consider the use of
nuclear power to be detrimental to human health. My
suggestion is that in the future every plant utilizing
nuclear power be labeled as doing so, thus allowing
the public to make an informed decision about whether
they wish to invest in a particular stock.
21
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Ruth C Clusen
ENVIRONMENTAL AND HEALTH EFFECTS RESEARCH:
THE VIEW FROM DOE
Ruth C. Clusen
U.S. Department of Energy
TEST OF COMMON SENSE
RUNAWAY REGULATION
THE CAUSE IS RIGHT
My office recently received a Freedom of Information request that was a bit
unusual. The writer, who claimed to be an environmentalist, wanted a list of three
valid laws that could not be carried out because they failed to meet the test of com-
mon sense. I can't tell you yet what our answer will be. The lawyers are still looking
at it. But the writer may have a point: Do our environmental laws always make sense?
As one who is sworn to obey the laws of the land, I cannot do other than uphold, to
the best of my ability, the statutes that come within my purview. Nevertheless, I can
understand why the common sense quotient of some legislation might be questioned.
A former Deputy Administrator of the Environmental Protection Agency, John
Quarles, recently wrote an essay for the Washington Post headlined "Runaway Regula-
tion? Blame Congress." I shall not comment on his argument that Congress is at
fault for the proliferation of regulations. He says the implications of statutes seldom
are understood fully at the time of enactment. The result is that the public rebels, he
argues. Mr. Quarles made a point in his essay that I believe is worth quoting. He
wrote: "The irony—and the tragedy—of these characteristics of regulatory legislation is
that they generate criticism of the basic regulatory programs despite the fact that those
programs may be entirely sound. In the environmental area, progress toward control of
pollution would be impossible without strong regulation. The principal programs do
make sense . . . ."
Congress, which was designed to be a representative body, does indeed represent
the American people. Many in this country argue with the content of our laws. Few
argue, however, with the basic goals of those laws. And that is the test of our form of
representative government.
People want a clean, safe, healthy environment in which to live. And they
want it to stay that way for their children and grandchildren. The instinct of self-
preservation is manifest in mankind's concern for future generations. Despite the
implicit argument of the Department of Energy's correspondent that there are laws
that do not make sense, I believe that he will receive no list from DOE. Sure, we
have done our bit in pushing the Federal Register past 27,000 pages in 1978, with
23
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MELDING SEEMINGLY
CONFLICTING GOALS
ACTION IS DEMANDED
NATIONAL ENERGY PLAN
perhaps a higher number this year, but the cause is right. Clean air, clean water, and
clean soil are necessary for this generation's well-being and for that of succeeding
generations. The laws do make sense. We believe that. And we must administer them in
that belief. For there are no more common-sensible goals than maintaining energy
supplies and improving our environment.
The first day's program of this Fourth National Conference emphasized the
efforts of EPA and DOE in the search for compatible solutions to the energy/
environment dilemma. Today's program emphasizes environmental and health effects of
energy research and development. The hypothesis that a dilemma exists seems to be
countered by the existence of research aimed at saving us from that seeming predica-
ment. Does this nation, through its government, really have to choose between two
separate but equal propositions? Is it really either all the energy we can produce with
concurrent filth and hazards or pristine safety with creeping starvation? Is it DOE
versus EPA in the gladiatorial ring? Obviously the answer to all those questions is no.
If the answer were yes, we would not be participating in this joint conference.
The fact of this conference also means, however, that there are big problems in
melding energy and environmental goals. That's why EPA in its pursuit of environ-
mental protection contains units concerned with energy production. In like manner
DOE, in its pursuit of energy development has programs aimed at protection of the
environment. And both agencies have been instructed by the people's representatives to
work out that melding of seemingly conflicting goals while at the same time side-
stepping economic pitfalls. Let me be candid with you. My Office of Environment is
part of the Department of Energy. My office shares the mission of DOE to make sure
that this country's energy needs are met. Some call my office the millstone around
DOE's neck. Others would call us sycophants. But the best way to state our job is to
quote the Energy Organizational Act of 1977. That law says that the ultimate goal of
the Office of Environment is "to assure incorporation of national environmental goals
in the formulation and implementation of energy programs, and to advance the goal of
restoring, protecting, and enhancing environmental quality, and assuring public health
and safety." And I say that is just common sense.
There are and should be no conflicts between our agencies or any others within
the Federal establishment. Yes, there are difficulties in policymaking. But the cynical
response of doing nothing is not permitted. There must be trade-offs. The law demands
trade-offs. The courts cannot decide, because these are basically political questions.
Politicians constantly risk their careers trying to balance goals that seem at odds.
Action, any action, will arouse opponents. Yet action is demanded, and it is taken.
Government employees, for the most part, are outside partisan politics. But they are
part of the American body politic. They are paid to make tough decisions in fulfilling
the laws they administer. They must analyze the issues and communicate that analysis
to all levels of public and private communities. And they must make sure that the
effects of policy decisions are founded on careful and comprehensive analysis.
That quality of decision cannot be reached without superior research findings.
We in the Office of Environment strive for superior research. Right now a committee
from the National Academy of Science is looking at the quality of our research into
the health effects of low-level ionizing radiation. A report is due this summer. DOE's
nonnuclear energy research bylaw is subject to a continuous review by another agency,
now the EPA. This year EPA is looking at DOE's environmental planning and review
procedures. DOE is working with EPA, the Department of Transportation, and the
National Institute of Occupational Safety and Health on the emissions of diesel
engines. Those are three examples of how the Office of Environment is reaching for
quality in its research efforts.
The President's second National Energy Plan constitutes marching orders for the
Department of Energy and its components. The plan anticipates that decontrol of
domestic oil prices will restrain the overall use of oil by reducing its importation and
stimulating production at home. That should increase reliance over the coming years
on coal and nuclear power, and bring on the development of a shale-oil industry.
24
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SYNTHETIC FUELS
EMISSION PROJECTIONS
SOLID-WASTE PROJECTIONS
Those developments will make necessary intensive efforts to resolve the environmental
problems connected with the use of those fuels.
Some synthetic fuels, such as shale oil and coal liquids and gases, are expected to
become economically attractive in the '90s. The air pollution that could be caused by
the burning of those fuels will have to be controlled. Water problems are associated
with the production of shale oil. Large quantities of water will be consumed in mining
and processing the oil shale, disposing of waste, and in replanting stripped areas. In
addition, there are problems with water supply contamination. Synthetic fuels based
on coal will require increased mining, and the processing can result in the release of
toxic substances inside and outside the plants. Actual environmental effects are still
uncertain because no commercial-sized plants have been built. Research is underway,
however, to develop information on which to base standards and controls for protect-
ing public health and safety.
The major unresolved technical problem of nuclear energy is the disposal of
radioactive wastes. Also, the siting and operation of nuclear plants must be done with
care because of public concern with radiation releases.
Solar energy is relatively benign for environmental purposes when compared
with conventional fuels. Some solar processes, however, could consume significant
amounts of water or use large land areas. And combustion of biomass adds carbon
dioxide to the atmosphere.
We in the Office of Environment have the lead among Federal agencies in re-
search on the effects of increased C02 levels in the atmosphere. In the last century
and a quarter the amount of carbon dioxide in the earth's air cover has gone up by 10
percent. About one-fourth of that increase has occurred within the past 10 years. If
the trend continues, it is conceivable that the levels could increase by two or three
times in the next century. Existing computer models predict a 2 C to 3 C rise in the
average surface temperature for each doubling of the carbon dioxide level. We must
know more about this phenomenon; thus the research effort.
Other air emissions are known to be environmentally hazardous. The Clean
Air Act Amendments of 1977 call for stricter emission controls by 1985. Enforcement
of those will reduce emissions of particulates, hydrocarbons, and carbon monoxide
by the year 2000, according to projections. Sharp reductions are expected in particu-
late emissions through the upgrading of controls on existing and new coal-fired generat-
ing plants and industrial boilers. Sulfur oxide emissions in 2000 are projected to be
the same or slightly less than in 1975. Increases in sulfur dioxide from coal burning
would be counteracted by improved efficiency in control devices. Total nitrogen oxide
emissions are expected to increase by more than 30 percent by the turn of the cen-
tury. In certain regions, nonattainment of air quality standards, or regulations prohibit-
ing significant deterioration of air quality, may restrict energy development.
Water pollution remains a widespread problem despite national efforts that have
improved water quality during the last decade. The nation's energy needs are expected
to quadruple water consumption by the end of this century. Coal mining and process-
ing operations could cause substantial increases in total dissolved solids releases. Other
releases into waterways would be of oil, greases, and sulfates. Total dissolved solids are
projected to double by 2000, but total suspended solids are expected to decrease
slightly. Nutrients and biological energy demand from energy sources are projected to
remain near their 1975 levels.
Now to turn to solid waste. Noncombustible solids currently remaining after
conversion of solid fuels and sludges from energy-related pollution control devices
account for about 17 percent of all solid waste produced in this country. Projections
for the end of this century show increases of several times as the result of greater coal
usage. Challenges are posed for dealing with larger landfill volumes, leaching and
transport of undesirable contaminants, and disposal of hazardous wastes.
25
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RADIOACTIVE POLLUTANTS
THE ENERGY/SAFETY
SCALE
What about radioactive pollutants? The energy plan projects nuclear power
plant increases from threefold to sixfold by 2000. Three types of pollutants must
be handled: solid wastes such as spent fuel and reactor parts, liquid waste containing
low levels of pollutants from nuclear plant cooling, and, finally, reactor off-gases. The
combustion of coal and oil may also produce radioactive pollutants, but to a much
lesser degree than from the nuclear processes. Radionuclide emissions by 2000 may be
up ninefold over 1975. But the potential level of exposure to the public would be
far below that from natural sources, medical uses, and other technology-caused
emissions, such as plane travel.
The United States need not make premature decisions about the use of new
technologies as long as further information about their environmental and health
characteristics is developed along with the technology. The same is true for their
technical and economic feasibilities. That's why it is necessary to develop a number
of options. We would have the flexibility to turn from one technology to another
or from one source to another if one or more supply options proved to be unaccept-
ably hazardous. It is the job of my Office of Environment to help the country prepare
to make those decisions. We do not work alone, either within the Department or
within the Federal establishment. It is a cooperative venture. And it is also a very
difficult one.
Nevertheless, we must all work toward solutions. We must balance our energy
requirements with health and safety demands. We can ignore neither side of the scale.
Our children and grandchildren depend upon us. We have got to use common sense.
26
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ental
lations
V *e
• ' r* t,
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ENVIRONMENTAL REGULATIONS: AIR
Walter C. Barber, Jr.
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
A LONG DEBATE
SETTING THE STANDARD
The Clean Air Act amendments of 1977 concluded a long debate between
environmentalists and industry over the adequacy of our new source performance
standard for steam electric power plants. At that time there was evidence that we
were going to burn a lot more coal and we needed to again look at the question
of whether low sulfur coal should be treated to nearly the same degree as high sulfur
coal. There was substantial concern that the eastern coal markets would be displaced
by imported low sulfur coal—to the eastern markets, imported means bringing it in
from the west—and there was substantial concern in the environmentally oriented
community that doing less than the best in the west would result in increased emis-
sions, feasibility impairment, and general degradation of air quality in and around
the parks.
That the Act required EPA to review the standard clearly indicated that Congress
felt the standard of 1.2 pounds per million BTU's was inadequate; Congress remanded
the standard to EPA to strike another energy environment and economic balance for
steam electric power plants, giving particular consideration to the question of the
degree of control required for low sulfur coal-fired power plants. We did that. It took
a long time. Most of you probably followed the saga in the press and in the Federal
Register. We promulgated that rule and it appeared in the Federal Register.
In setting the standard, our approach was to look at both individual plants and
model plants. We were also concerned about what the environmental impacts relating
to individual plants were. At the same time, we needed to take a careful look at what
a more stringent standard might do to the overall energy economy; what we were
going to do to both existing and new plants; and what the net effect on the environ-
ment, the economy, and the coal markets would be. That is the exercise that took
so long and that has been debated at some length. The final standard calls for essen-
tially full control of all coal-fired power plants. It provides an opportunity for the
sulfur oxide emissions to meet a slightly less stringent standard in the event that the
coal is low enough in sulfur and it allows new technologies that have substantial
economic and energy benefits to penetrate the marketplace.
29
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SO2 EMISSIONS
REDUCED
FULL CONTROL
VS PARTIAL CONTROL
NEGATIVE ASPECT
OF REVISING STANDARD
Total coal production in the United States is currently 650 million tons. By
1995 that amount will increase two and a half to three times. Had we not changed
the standards, that is had we left it at 1.2 pounds per million BTU, we would have
had from the power plants subject to the standard-and those are the power plants
that will come on line between late 1983 and 1984 along with a set of plants that will
come on line between 1984 and 1995-7 million tons of SC>2 emissions in 1995. So,
basically, the revision to the standard will reduce by more than 50 percent the S02
emissions associated with the subset of plants that are subject to this standard.
From power plants, we now have about 19 million tons of SC>2 emissions nation-
wide. Had we not changed the standard, we would have almost 24 million tons in
1995. The way we promulgated the change in the standard, we expect to have about
20-1/2 million tons in 1995. Three million tons is the difference between what we
would have under the old standard and what we would have under the new. We
had a difference of about 3.9 million tons between the old standard and the new one,
but we won't see that 3.9-million ton difference because as we make power plants
more expensive, and it is obvious that we are making them more expensive, people
tend to build fewer new ones and to use the old ones. Old power plants are substan-
tially dirtier than new power plants. The average coal-fired power plant in existence
now emits about 80 pounds of S02 per ton of coal burned. The power plants that we
are talking about are going to emit about 12 pounds of SO2 per ton of coal burned so
we are going to get a substantial shift in the SO2 emissions from power plants.
Most of what I am going to talk about today has to do with SO2. There is a
pretty vigorous particulate standard that was promulgated—0.03 per million BTU,
which is about a 70-percent reduction from the current standard and which will
require aggressive application of either precipitators or baghouses on these power
plants. There is a marginal increase in stringency in the NOX emission limit from the
current 0.7, down to the 0.5 or 0.6 range.
The current standard shows about 23.7 million tons, and the revised standard
about 20.5 million. This breakdown is the total national emissions. There are two
alternatives: the so-called full control alternative that was favored by the environ-
mentally oriented community and the partial control or 33-percent alternative recom-
mended to us by the Department of Energy, which was similar to the recommendation
provided by the utilities. The most stringent alternative results in more emissions than
the alternative we have adopted, which may be counterintuitive, but that is the way it
works. That is particularly significant in the east where there is a several hundred-
thousand-ton difference. The reason is simply that existing power plants are used more
as the standard becomes more stringent and the full control across-the-board alternative
is substantially more expensive. As a result, it encourages people to run coal plants
that emit 80 pounds of S02 per ton rather than build coal plants that emit 12 pounds
of S02 per ton.
Congress directed us not to create an unreasonable incentive to bring low sulfur
coal into the East thereby displacing eastern coal markets. Our analyses showed that, if
we didn't change our standard, by 1995 we would have about 122 million tons of coal
coming east of the Mississippi. Under the revised standard we would have 70 million
tons, or about 50 million tons less. Congress did not want us to disrupt the coal
markets. Under the present standard, Appalachia produces 400 million tons and the
Midwest, 150 million tons. This production increases with our revised standard.
Even if we retained the current standard of 1.2 pounds per million BTU, we are
going to have 1.4 million barrels a day of oil being burned in power plants in 1995,
which means we will be putting just as much oil into power plants in 1995 as we are
putting into power plants now. Making the standard more stringent unfortunately
encourages people to put more oil into power plants; under the most stringent alterna-
tive it would be 400,000 barrels a day; under the alternative we have selected it
would be about 200,000 barrels a day. That is one of the negative aspects of revising
the standard.
The plants that we have now or that are being constructed are subject to the
current 1.2-pound NSPS. There will be between 15 and 16 million tons a year of S02
30
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ECONOMIC IMPACTS
INCREMENTAL
ANNUALIZED COST
EMISSION RATE CEILING
emissions in 1995; they dominate the system. As we make the standard more stringent
we can bring 7.5 million tons down to 3.1 million tons. None of the alternative stan-
dards brought that number any lower than the finally selected one at 3.1 million
tons. If we don't change the standard, the emissions from all power plants, would be
about the same as with the revised standard. Once again, this is because making things
more expensive under the full control option encourages people to use the SIP/NSPS
plants more.
We have used four or five indicators of economic impacts, one being the average,
monthly residential bills in 1995. If we don't change the standard they are going to be
$53; if we do change the standard they are going to go up 21/2 percent which is about
$1.30 a month. Indirect consumer impacts, the increased cost of purchases, are going
to be about the same, another $1.30. To the average residence, in 1995 this standard is
going to cost $2.50 over an electric bill that now runs about $53 direct, and the $53,
which is in current dollars, compares with a current average residential bill of $26. So,
for reasons that don't have a lot to do with this standard, everybody's electric bill is
going to double. That is because we are going to use more electricity for more and
different kinds of appliances and labor, transportation, and fuel rates are going to go
up, as well as construction rates, at a level faster than the rate of general inflation.
Another indicator is the total increased utility capital requirement. There was
concern that this standard would make it difficult for utilities to find money to
operate. We looked fairly carefully at the availability of capital to build new power
plants and found about $770 billion between now and 1995 had to be spent on new
capital plants. This standard basically adds between zero and $10 billion to that.
The total capital change obviously reflects decisions not to build new power plants.
The capital cost of the control equipment that we are talking about would be in the
tens of billions of dollars, in the 1995 timeframe, about $30 billion.
Incremental annualized cost was an indicator as to how much of the total
national electric bill this standard was going to cost; the total national electric bill in
1995 is estimated at $175 billion. This standard increases it somewhere between $3
and $4 billion, depending on the choice made. This makes the decision process diffi-
cult because, on one side, the most stringent alternative, the full control, is only $414
billion more than the $175 billion we already have to collect. On the other side, it is
$11/2 billion more than the alternative that we selected, and $1 billion is still a lot of
money even when compared with $100 billion.
The present value of incremental utility revenue requirements is just that—all
of the costs accrued to the utility through the useful life of those plants brought back
to the present ends up being about $30 billion and the incremental cost of S02
is about $1,000 a ton. Under the most stringent standard it got up to $1,400 a ton.
None of them got under $1,000 a ton. So, compared with our current several hundred
dollars a ton for SO2 control costs, this one is not cheap.
A fair amount of debate in the final stages of this standard surrounded the level
of the maximum emission rate. We looked at the ceiling question. The press was
interested because there were coal miners who felt that we were prejudiced against
the very high sulfur coals prevalent in the northern Appalachian and midwestern area.
It turns out that the way we have structured the standard and the way coal reserves
are deployed around the country, there isn't very much of that coal likely to burn
relative to the other available coals. We therefore looked at very low ceilings, as low as
0.6 pounds per million BTU averaged monthly and decided to consider making every
plant emit no more than 0.6 pound per million BTU. That turned out to be a fairly
cost effective way to get S02 out of the air, and the economists reveled in the idea of
shifting our coal market from the high sulfur coals to the low sulfur coals. One risk
when using national-scale economic models is that they do things which don't have a
lot to do with reality.
When pushed down to 0.6, all that is done is to take people who are now mining
0.8- and 1.0-pound coal and shifting them over to 0.6-pound coal. It is all new mines.
Instead of mining that coal we will mine 0.4-, 0.5-, and 0.6-pound coal. We have two
to three hundred years worth of coal. Let us just shift our emphasis. But it turns out
31
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EFFORT TO STRIKE
A FAIR BALANCE
that a lot of people have invested large sums of money to assemble the reserves which
they are planning to mine over the next 10 years and not all of those reserves happen
to be in the less than 0.6-pound range. It became evident to us that we were going to
disrupt coal markets over the next 10 years until this big shift could take place. That
didn't seem to be particularly compatible with the effort to shift to coal for our new
generating requirements. So that is where we ended up. We ended up with a 1.2-pound
ceiling. This is what the roughly 350 power plants will be doing in practice. The way
we have structured the standard there is some encouragement for them to get under
the 0.6 level. We expect that of the 350 power plants, roughly 278 will be less than
0.6 in terms of average monthly emissions. We expect that about 50 will be between
0.6 and 1 and that about 22, between 1 and 1.2. That is one issue, I think, that is
fairly well developed in the preamble of the regulation and you may come to a clear
understanding by reading that.
I would just close by saying that writing rules that are going to affect the energy
industry from the environmental perspective has become substantially more complex
and more time consuming. We are endeavoring to deal with these monumental prob-
lems that are associated with billions of tons of coal, millions of tons of sludge, and
billions of dollars to the consumer. We have come a long way since 1972 when we
could put a rule like this in the Federal Register with a few marks on the back of an
envelope as to cost estimates. I think that this standard represents an effort by the
Agency to strike a fair balance. If you look carefully at the numbers in the Federal
Register, you will see that we have gotten what is nearly, if not entirely, the environ-
mentally preferable option. We have identified a way to give the utilities enough
flexibility so that they can save about a billion dollars a year.
32
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Swep T Da
THREE GROUPS OF WORK
PRIMARY FOCUS
ENVIRONMENTAL REGULATIONS: WATER
Swep T. Davis
Office of Water Planning and Standards
U.S. Environmental Protection Agency
In industry, water regulations traditionally have not had the cost impact and
generated the controversy that air regulations have. The problems that air regulations
have to deal with, either directly or indirectly, run head on into energy industries or
energy policy, which is not the case with water regulations. This is.changing somewhat
because the relative importance of energy is increasing in the water regulations. These
increases can be explained, first, by the fact that an energy-cost increase will make the
energy factor more important simply by increasing the overall costs of those regula-
tions and, second, by the fact that the phenomenon is exacerbated somewhat because
the second round of technology requirements, primarily those for industry, are ex-
pected to be much more energy intensive than the first round of standards. There is a
much greater reliance, for example, on reuse and recycle technologies, and these, in
general, require greater amounts of energy.
The work we are doing in water as it relates to energy can be put into three
groups. The first contains cases of direct regulation of energy that currently is a major
industrial factor in the energy field, examples being the steam electric utilities industry,
the petroleum refining industry, and the coal mining industry. The second group
contains the emerging energy technologies which, by definition, are not now regulated,
but which we are working on so that when they finally become commercial, regula-
tions for water pollution will already be understood by the industry. The third group
contains those cases where we regulate industries that are not energy industries but,
because they are in the process of complying with water regulations, would have
energy requirements and an energy impact.
I will focus only on the first two groups. Although there are greater energy
impacts on the nonenergy industries, I think the energy factor, in most cases, is still
not the constraining factor but that overall cost and economic trade offs are. But
compared with the cost of air control regulations, the energy impacts in those indus-
tries are relatively minor. The commercial energy industries in this country and the
ones that we regulate in the water pollution programs are the primary ones that we
33
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FOCUS ON TOXIC
POLLUTANTS
PETROLEUM REFINING
INDUSTRY
STEAM ELECTRIC
UTILITIES
worry about right now. They are steam electric utilities, petroleum refining, coal
mining, and ore mining. I will comment mainly on the steam electric and petroleum,
the two industries in which we have progressed the most in developing our current
round of regulations.
The regulatory work in the Water Act generally lags behind the Clean Air Act
by 1 to 2 years because the Water Act itself was passed at a somewhat later date. The
whole regulatory effort in water, going back to its statutory basis, is lagging somewhat
behind the air program. My comments will therefore be dealing with regulations that
are still 6 months to a year away.
In the petroleum refining and steam electric utility industries, our focus in this
round of regulations has primarily been upon toxic pollutants. In the 21 industries we
are looking at, which include these two industries, we have found some measure of
toxic pollutants in practically every industry. We are setting aside industries that do
not show substantial amounts of toxics or that have 1983 standards that already
control them substantially and we are focusing on only the remaining industries. Even
within those industries, for example within the petroleum refining industry, we have
found in the untreated waste streams about 6 or 7 of the 129 pollutants we are
focusing on. Of those 129, about 41 are found even in the treated waste waters after
what we call best practical technology of the 1977 requirements. Of that 41, we,
nevertheless, will focus on a still much smaller number for regulatory purposes, partly
because all of them are not found consistently enough or in high enough quantities to
worry about and partly because from a practical point of view it doesn't make sense to
attempt to regulate every pollutant.
Basically, there are three regulatory approaches we are looking at in the petro-
leum refining industry. The first is the reuse and recycle technologies that are well
established within this industry. Practically all industries recycle to one degree or
another as a result of the 1977 requirements. The 1984 best available technology
(BAT) requirements will probably include some degree of additional recycling and
reuse as part of the overall regulatory structure. The second regulatory approach would
be the end-of-pipe treatment and the primary one being studied is powdered activated
carbon. There is a substantial difference in the cost of powdered activated carbon and
granular type activated carbon. A rough estimate of what it would cost annually,
including output and maintenance cost, for the entire industry to install and operate
powdered activated carbon is $66 million a year, which is relatively small compared
with what we are spending for air pollution control. The cost for granular activated
carbon would be approximately five times that amount, or about $360 million a year.
For a very minor sacrifice in pollutant control, there is about a fivefold savings in cost
by using powdered activated carbon. The third regulatory approach is no-discharge of
waste water pollutants which is simply an extension of the reuse and recycle approach.
It has been demonstrated in the petroleum refining industry and it is most commonly
found in the western states where water shortages have forced these industries to
develop much more advanced waste-water management practices. We currently know of
about 50 or 55 refineries that now practice this.
Like the petroleum refining industry, the steam electric utility industry is, to an
even greater extent, a very high volume industry. This is true not only for thermal
waste streams but also for the so-called chemical waste streams, which may be rela-
tively small within this industry but compared with many other industries are still very
large. We find that the pollutant problem is one of quantity, as opposed to concen-
tration level. In many cases the concentrations are extremely low. However, because
the pollutants are often heavy metals or are very persistent in the environment, their
concentrations are very high in volume and can still be of concern.
Within the steam electric utilities industry we have focused our attention primar-
ily on cooling water waste and ash transport streams. By far the largest in volume is
the cooling water waste stream in which the concentration levels of pollutants are
extremely low. Rather than focusing on individual organic toxics, we will be primarily
focusing on residual chlorine and the concern about chlorine itself being toxic, at least
in the higher concentrations. Residual chlorine greatly increases the probability of
chlorinated hydrocarbons being created in the waste streams before discharged.
34
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EMERGING TECHNOLOGIES
OIL SHALE
GEOTHERMAL
Probably the more controversial and the more expensive in terms of regulations that
might finally be proposed and promulgated are ash transport streams. They come in
two or three different forms. We focus mainly on fly ash from electric type precipi-
tators and on bottom ash. Although we are not focusing on it very much, there is a
third waste stream soon to be generated, at least in an official sense. It is ash that
results from the scrubber process. Depending on the kind of waste stream, we are
considering alternative chemical additives for dealing with some of the problems that
we find in cooling water streams. Petroleum refining reliance upon water reuse from
recycle is a primary alternative mode of ash transport. End-of-pipe treatment is most
applicable for ash transport but the extremely high volume of the cooling water stream
makes it a much more difficult option to consider from an economic point of view.
Last, but not least, management practices themselves are being studied. The ways
in which plants are operated can greatly alter and reduce potential environmental
impacts from, for instance, the cooling water stream. This is an option we will be
trying to fit into the whole regulatory package. It is a much more effective and a
much cheaper approach than trying to do end-of-pipe treatment.
Because of the large size of the plants involved in the utilities industries, the
volume of the waste streams, and the large numbers of plants, it is easy to conceive
a price tag for water regulations and control in excess of $1 billion.
Although none of our regulatory efforts at this point include the emerging
technologies, there is a great deal of effort in terms of actual dollars and man-years of
effort under way in my office. There is even greater effort in other parts of EPA and
in other agencies, such as the Department of Energy and the Department of Interior.
Our objective is to try to get ahead of a power curve in the emerging technologies
and to determine in advance what types of pollutants can be generated, how serious
they might be, and what type of technology or management steps can be taken to
deal with them. We also must try to lay these out and make them well-known to
the industry before they reach the commercial stage so that the proper kinds of
controls can be included in the design. We have had very bitter experiences, in some
cases, with the earlier regulatory effort; it isn't possible many times to adequately
deal with the toxic problem and other pollutant problems in a retrofit situation and
even when we can deal with them, it is at great expense and with great controversy.
Three technologies that I will discuss next are oil shale, coal gasification and
liquefaction, and geothermal which are only in the development stage. Based on what
we have done so far, mainly work in research and development, there could be signifi-
cant concentrations of toxic pollutants generated from oil shale. One advantage of
looking at this early is that there are a number of options for dealing with oil shale,
including studies that indicate feasibility of zero discharge of waste water pollutants.
Industry is considering zero discharge types of requirements in designs in oil shale
technologies. A big factor is that a tax credit is being considered in Congress for oil
produced from oil shale which would provide a substantial incentive for this techno-
logy to be accelerated commercially.
We are also exploring coal gasification and liquefaction for toxic pollutants. We
have found, in some cases, inorganics from the coal itself, phenolic compounds, and
some aromatics. It is early to say what can be done, but these are pollutants that we
have been able to deal with in other industries. We are starting to do feasibility work
on bench scale plants and, we hope in the near future, to start doing research and
development on commercial power scale facilities.
We are not focusing very hard on the entire toxics list in the case of geothermal.
There are a relatively small number of pollutants that we would be concerned about
but I can't give you any quantitative sense of how great a problem this would be.
It is simply the list we would expect. It includes boron, bromine, ammonia, arsenic
and mercury. There are numerous ways of dealing with them, including treatment
technologies and process approaches which we will try to explore as we learn more
about the exact quantities of pollutants generated.
35
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Steffen Plehn
REGULATION
FOR SAFE DISPOSAL
IMPACT OF THE RESOURCE CONSERVATION
AND RECOVERY ACT ON UTILITY WASTE
Steffen Plehn
Office of Solid Waste
U.S. Environmental Protection Agency
The Resource Conservation Recovery Act (RCRA), which was passed in 1976,
has two goals: to protect the public health and the environment from the improper
disposal of solid waste and to encourage and facilitate the conservation and recovery
of resources from solid waste. Under this Act, EPA has essentially three programs.
Taking them in reverse order, there is a program to encourage the recovery of
energy and materials primarily from the municipal solid waste stream. This program
intersects with many utilities with regard to the use of solid waste, or fuel derived
from solid waste, for the production of energy. Statistically the energy value of
municipal solid waste in standard metropolitan areas is equivalent to about 400,000
barrels of oil a day. In Europe, and particularly in Japan, that waste is turned into
steam and then into electricity, or used directly as steam. We are well behind those
countries but are coming along. The technologies we now have and our most diffi-
cult problems are those that relate to institutional constraints for getting communi-
ties organized to procure and operate those plants, but we have a program to
accomplish this.
Congress set up two programs for the safe disposal of wastes. One is under
subtitle C of the RCRA and the other under subtitle D. For regulation of hazardous
wastes, Congress called for a cradle-to-grave Federal program that they hoped all
states would adopt and implement. For all other solid wastes, Congress determined
that the primary responsibility should rest, as it now does, with state and local
governments and that the Federal Government's role should be limited to developing
criteria that would define sound landfill disposal. The states would then develop
regulatory programs consistent with the Federal criteria.
We proposed a regulation about a year ago which we expect to promulgate
in July. The regulation will establish performance requirements, will ensure that land
disposal will not pollute ground water, surface water, or add to air pollution and that
land disposal sites are not placed in environmentally sensitive areas which are flood
plains, wet lands, et cetera.
37
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CRADLE-TO-GRAVE
PROGRAM
CHARACTERISTICS
OF HAZARDOUSNESS
SPECIAL WASTES
Under subtitle C of RCRA, hazardous waste is defined as solid waste that may
cause or contribute to an increase in serious illness or mortality because of its
quantity; concentration; or physical, chemical, or infectious characteristics or may pose
a substantial present or potential hazard to human health or to the environment when
improperly treated, stored, transported, disposed of, or otherwise managed.
As I said earlier, the Act provided for a cradle-to-grave regulatory program for
wastes. Congress determined that wastes are so mobile that they must be brought
into a regulatory system at the time they are created and must be regulated until
the time they are finally disposed of. We are required to promulgate seven regula-
tions which (1) define what a hazardous waste is; (2) establish the responsibilities of
generators of wastes; (3) establish the responsibilities of transporters of wastes; (4)
set design and operating standards for facilities at which wastes are either treated,
disposed of, or stored; (5) define a permitting system for those facilities; (6) estab-
lish the rules under which we would authorize states to run the program; and, finally,
(7) define a regulation requiring notification by generators of wastes as soon as the
regulations are promulgated.
The Act provides two specific means by which a hazardous waste can be
identified. One is simple tests that test for four characteristics of hazardousness.
These are whether the waste is (1) ignitable, (2) corrosive, (3) reactive, or (4) toxic.
Feeling that we needed more help from the world, we also proposed two additional
characteristics for public comment: (1) radioactivity and (2) organic toxicity or more
specifically mutagenicity, bioaccumulation, and other elements relating to organic
toxicity. The second means by which a waste can be determined to be hazardous is if,
based on available evidence, the administrator determines that it is.
In bur proposed regulation we listed about 150 waste streams or particular
wastes which we believe the evidence indicates are hazardous. Many of those are
in the area of organic toxicity because our characteristic for determining organic
toxicity is not sufficiently well developed and validated to serve as a keystone for this
regulatory program.
As we were developing this hazardous wastes regulation, we realized that some
of the high volume wastes that are produced in the process of electricity generation
could potentially be hazardous. We concluded that there was a possibility that when
tested, fly ash and bottom ash could possibly be toxic, corrosive, or reactive. Because
of trace metal concentrations in sludge, scrubber sludge could potentially be toxic. We
also concluded that it would not be appropriate to apply the range of design and
operating standards which are now developed to ensure that the Love Canals of the
future do not occur to large volume and comparatively low hazard wastes.
We, therefore, proposed a special classification for handling those wastes which
we call special wastes. Coal utility and other steam power plant wastes, coal mining
and milling wastes, and uranium mining wastes are specifically identified as special
wastes. Such wastes would be exempt from financial responsibility requirements and
treatment, storage, and disposal requirements that would be applied to other hazardous
wastes. We need to know a lot more than we now know about how to properly
manage special wastes.
If wastes violate any of these characteristics, they would then be subject to
a very limited number of requirements: waste analysis, the siting of new sites, security,
record keeping, and closure and monitoring.
Industry was extremely concerned about what proportion of these wastes might,
in fact, tilt against these characteristics. Since December, industry and we have been
doing a lot of testing to see what the score is. At TVA, 10 samples of fly ash and
bottom ash were tested for characteristics of hazardousness. In nine of those, neither
the fly ash nor the bottom ash flunked and the 10th sample appears not to have
either, but it needs more work. If those particular data are an indicator, fly ash and
bottom ash would be affected by this regulation as it was proposed.
38
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OTHER FEDERAL
STATUTES
AGGRESSIVE AND FORCEFUL
ENFORCEMENT
Working in conjunction with EPA's Office of Reseach and Development, we
have begun to accumulate data for analysis to determine management standards for
the protection of the environment and the public health. We are currently in the
process of selecting sites for this analysis. We will then conduct full field investiga-
tions, including monitoring of surface water, ground water, and the air at about 10
mining and 16 utility sites. We expect that by 1982 the results of these studies will
put us in a position to propose regulations for the management of wastes. An amend-
ment to RCRA proposed by Senator Huddleston says that EPA would not proceed
under subtitle C of RCRA with any regulation of these utility wastes until the studies,
which I have described, are complete. At that time we will decide whether to have
regulations. Whether that amendment will survive, I don't know, although my expecta-
tion is that it will.
Two other federal statutes affect the management of solid waste. One is the
Surface Mining Control and Reclamation Act under the Department of Interior which
regulates surface mining and also waste disposed on the surface as the result of under-
ground mining. We and the Department of Interior's Office of Surface Mining have
overlapping authority for the regulation of those wastes. We have been working with
the Department of Interior to delegate our responsibilities under RCRA to the Office
of Surface Mining. We find their disposal criteria satisfactory except that they do not
require ground water monitoring of all disposal sites. We believe that these sites should
be monitored so that action can be taken to deal with problems before an aquifer is
polluted.
Another Act of interest is the Uranium Mill Tailings Radiation Control Act
which Congress passed last fall. This includes the disposal of uranium mill tailings,
both radiological and nonradiological hazards. The law says that EPA is to write
the regulations under this Act, and that the Nuclear Regulatory Commission is to
enforce them through their permitting system. The statutory dates for these regula-
tions are November 1979 for inactive sites and May 1980 for active sites.
It is important to understand that the Resource Conservation and Recovery
Act addresses, almost solely, the management of hazardous wastes from the time
of its promulgation. The Act mandated the establishment in 1976 of a regulatory
structure that would, over time, regulate all waste disposal. We have just recently
come to the realization that the problem of past inadequate disposal of hazardous
wastes is of an order of magnitude far greater than anyone had understood. We had
very limited legislative authority and virtually no resources with which to address this
problem. We are therefore reorienting and augmenting our efforts.
There are now more than 100 people working on the problem of inactive and
abandoned sites, with 144 cases under investigation. Seven imminent hazard cases have
been filed under RCRA and other EPA authority. Where we can make a case and
locate a responsible party, we are proceeding with enforcement aggressively and force-
fully. We look forward to the proposal of legislation to establish what is colloquially
referred to as the superfund, which would integrate our responses to inactive and
abandoned sites with our Spills Response Program for oil and hazardous materials
under Section 311 of the Clean Water Act and, also, provide resources to contain those
sites for which there is no evident and solvent owner and which pose a threat to public
health.
39
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mm'^^f^ mm^wm m^y
& answers
Leon Green, Jr.
General Atomic Company
Dr. Margaret E. Hamilton
Delaware Chapter, National Audubon Society
Howard Hagler
Resource Planning Associates, Inc.
Robert Roach
National Audubon Society
Jean B. Cornelius
Avon Lake League of Women Voters
Robert C. Gabler, Jr.
U.S. Bureau of Mines
Mark Gottlieb
Office of Radiation Programs
U.S. Environmental Protection Agency
John A. L. Campbell
Peabody Coal Company
Benjamin Linsky, P.E.
West Virginia University
Alex Wormser
Wormser Engineering
QUESTION
Will coal ash be regarded as hazardous because of its
radioactivity?
RESPONSE: Mr. Steffen Plehn (EPA)
Yes. We have announced in an advance notice of
proposed rule-making our current thinking as to how to
approach radioactivity as a hazard, not only with refer-
ence to coal but elsewhere. We have received comment on
that and will be working to improve and finalize our
thinking. I expect that in 1980 or early 1981 we will
propose a characteristic and move toward its inclusion in
the hazardous wastes regulatory program.
41
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QUESTION
The Department of Energy is committed to an
educational conservation program, but you are antici-
pating an increase in energy consumption and a doubling
of the average electric bill. How can these two viewpoints
be reconciled?
RESPONSE: Mr. Walter C. Barber, Jr. (EPA)
Doubling the average electric bill does not mean the
same as using twice as much electricity. There is a growth
rate in electrical demand nationwide, some of it asso-
ciated with increased use by individual consumers and
some of it associated with general growth in the econ-
omy. It is not the sole contribution to increased cost;
that has to do also with increased fuel, transportation,
and labor costs. The Department of Energy and the
Environmental Protection Agency worked together to
develop these projections. The total growth rate used as
the basis of the Department of Energy's projection is
about 2 percent per year.
QUESTION
Your comparison of the 1975 and the 1995 coal
production showed some rather startling increases in
regional projections, particularly in the Midwest and the
northern Great Plains. How realistic are those projections,
and how do they relate to the rest of the information
you displayed?
RESPONSE: Mr. Barber
The question is one of how we are going to get
the coal. An estimate has been made of the country's
total electrical demand, a demand which must be met by
some means. Because of limitations on nuclear power
generating construction, we project that most of the
demand will have to be met by coal-fired power plants.
The model used to estimate coal is an economic model,
which says that those two areas of the country are going
to a) experience increased demand, and b) have coal
available at a reasonable price. Whether the coal industry
can produce enough coal is another question, but it is
consistent with the estimates the Department of Energy
has been developing.
QUESTION
What plans are being made for public or community
participation in the siting of storage facilities for toxic or
hazardous substances?
RESPONSE: Mr.Plehn
The problem of siting is the most difficult problem
that will have to be solved if we are to achieve safe
hazardous-waste management. Everybody insists that
wastes be disposed of properly, but nobody wants the
disposal to be within his own range. Public opposition
is a very difficult problem. In an effort to involve citizens
42
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in learning about and participating in the siting of such
storage facilities, we have started a program called waste
alert. We are conducting a series of regional conferences,
to be followed by state conferences. Douglas Costle,
Administrator of the U.S. Environmental Protection
Agency, appeared before the National Governors' Asso-
ciation last February to bring the disposal problem to
their attention. He said that it is EPA's strong belief that
each state must develop procedures consistent with its
own constitution and laws to address the siting problem
systematically: to ensure that all the technical require-
ments for candidate sites are identified, to provide for full
public participation in the evaluation of those sites, and
also to assist in the final selection of sites. Although a
number of states are moving in this direction it still
remains our most difficult problem.
QUESTION
A headline this morning announced that the Envi-
ronmental Protection Agency had decontrolled all electric
utilities in Ohio. They will not be required to have
scrubbers, and they will be allowed to burn high-sulfur
coal. Those who have fought to force the utilities to get
scrubbers were banking on the backing of EPA. What are
the reasons for eliminating the standards?
RESPONSE: Mr. Barber
The Federal Government, in the absence of an Ohio
State Implementation Plan, adopted emission limits for
essentially all the major power plants in Ohio. We are
going to take another look at two power plants owned by
Cleveland Electrical Illuminating. Those two plants were
modelled using state-of-the-art techniques at that time.
We have decided that the models used when we set those
initial emission limits some years ago were inappropriately
applied. Rather than force those power plants into com-
pliance with potentially, and perhaps substantially, erro-
neous emission limits, we are going to reevaluate the
air quality data associated with them and set a revised
emission limit before they buy scrubbers. We have seen a
fairly clear error in the application of the modelling
techniques to these two plants in particular, so we are
going to maintain the status quo in those plants until the
modelling is completed.
COMMENT
We have been studying recovery of ash samples for
various metals from approximately 11 plants. All but one
of these samples arrived in plastic containers. That one
arrived in a tin-plated, steel can. Within about 3 weeks,
the wet bottom ash ate completely through the can,
meaning that it was clearly a corrosive material and that
it definitely would fit the definition of a hazardous waste.
The effects of the other samples are not known, because
they were in plastic, but some of the wet ash samples are
quite corrosive because they are very caustic.
43
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QUESTION
In regard to policy concerning control of radioactive
substances, to what extent does the Resource Conserva-
tion and Recovery Act (RCRA) allow development of
control technologies to deal with this, and to what extent
is it EPA's responsibility to develop these technologies?
Or is this more the responsibility of the private sector?
RESPONSE: Mr. Plehn
The basic orientation of RCRA is the establishment
and effective implementation of a regulatory structure.
There is ample authority for EPA to work on control
technologies for any particular waste. The degree to
which EPA will do that work depends heavily on the
resources available. Up to now, the work done in the
Office of Solid Waste has been very limited in that area.
RESPONSE: Dr. Steven R. Reznek (EPA)
The Office of Energy, Minerals and Industry is
working on the disposal of uranium-mining operations.
Once the first concentration step occurs, however, the
Office of Research and Development is no longer in-
volved. We aren't doing anything about developing radia-
tion protective methods.
QUESTION
There seems to be a question whether the coal
industry can meet the energy needs. The problem right
now is actually one of over-capacity with estimates of
approximately WO mil/ion to 150 million tons over-
capacity. The industry is closing down mines; we can't
sell coal because of the soft market, and this in a time
of great national concern about the energy crisis. The
reasons for this are hard to pin down, but one major
reason is air pollution regulations. My company had
to close a very large mine complex in Ohio because of
air pollution problems. There is concern in the industry
about the role that health effects will play in setting
new sulfur standards. As there is very little information
about this aspect, would you tell us how large a role you
expect health effects to play?
RESPONSE: Mr. Barber
The New Source Performance Standard is a tech-
nology-based standard, the intent of which is to ensure
that as we put in new capital stock over the next 50
years we do it cleanly and obviate the need to make
massive retrofits of our existing plants. Certainly health
effects data are sparse. There are two disparate opinions
resulting from that: one opinion says, when in doubt do
nothing; another opinion says, under conditions of uncer-
tainty take some prudent action. Other heads than mine
will decide on the degree of stringency to be applied
under conditions of uncertainty, but for every one who
thinks we are proceeding at too aggressive a pace on
sulfur oxide issues, there is one who believes we are
proceeding at too lax a pace.
44
-------
QUESTION
Although it is expensive from an energy viewpoint,
as we have enough coal, isn't expanded use of dry cooling
a feasible way to get rid of some of the troublesome
chemicals and thermal water pollution, particularly in
the East and Midwest, where water is in increasingly
short supply?
RESPONSE: Dr. Reznek
The Office of Research and Development has done
an extensive study of how much water is necessary to
produce energy, either electricity or synthetic fuels, and
they have looked with great care at alternatives to wet
cooling. A combination of wet and dry cooling is quite
an attractive alternative, particularly in the northern
areas of Montana and the Dakotas and in West Virginia.
Although there is a cost penalty, it is not too far out of
range. In areas where water has to be transported a long
distance to a plant, building the plant at the coal and
deciding to go wet/dry is the economic choice. To go to
dry by itself and eliminate all cooling water, either for
electricity generation or for some of the other processes
in these energy technologies that are coming along, going
to total dry cooling, eliminating all cooling water for
electricity generation or for some of the newer tech-
nologies, is an extremely expensive proposition though it
can be done. Two plants are using it today but at great
expense, and it actually changes the price of electricity
substantially. The normal price for irrigation water is
between $10 and $12 per acre foot, the volume of water
that would cover an acre in area. Energy would pay
between $100 and $200 per acre foot of water per
year, raising the production cost of electricity by about
2 percent. You would cut that in half, however, for
delivered electricity, so there is about a 1 percent increase
for zero water being put into the plant and going out,
except for the small amount of feed water.
RESPONSE: Mr. Swep T. Davis (EPA)
The Office of Water Planning Standards and Regu-
lations is basically setting nationwide standards. Often we
come across a case where something unique has been
done, that is feasible only because of a unique set of
circumstances. Sometimes that can be built into the
national standard, but usually it is very difficult to do so.
Also, our primary focus right now is on toxic chemicals.
Consequently, although there are some toxic chemicals
associated with the thermal stream, they are relatively
minor compared to what is contained in other industrial
waste streams, and we are not focusing on them. It is
true that water shortages exist all across, the country, but
the primary purpose in setting regulations is not to
conserve water; the primary focus is on toxic chemicals.
We would prefer industry response in the form of tech-
nology solutions that have secondary effects of benefit
for conserving water and other raw materials. Our role is
not to leap ahead of the normal economic process and
drive it solely for water conservation purposes.
45
-------
QUESTION
Does the sulfur that can be removed from coal by a
cleaning process at a mine subtract directly from the
sulfur that has to be removed at the point of use, and is
that true for industry as well as for electric utility
application?
RESPONSE: Mr. Barber
The standard applies only to electric utilities, and
the percentage of removal is an overall percentage from
the mine to the stacks. The sulfur, therefore, can be
removed anywhere along the way with credit. The law
requires that we set a similar standard for industrial
boilers, and we expect to propose such a standard in the
summer or fall of 1980.
QUESTION
A special waste category for fly ash is now being
proposed for industrial waste. Is that likely to be applied
to industrial boiler waste as well?
RESPONSE: Mr. Plehn
As it is proposed, it is expected to apply to both
industrial waste and industrial boiler waste.
-<* - . » .
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46
-------
session 3
chnology
-------
Michael A Maxwell
EMISSIONS PROBLEM
REGULATORY FRAMEWORK
SULFUR OXIDES CONTROL: FLUE GAS DESULFURIZATION
Michael A. Maxwell
Industrial Environmental Research Laboratory/RTP
U.S. Environmental Protection Agency
Michael D. Shapiro
Division of Fossil Fuel Utilization
U.S. Department of Energy
Mr. Maxwell:
One of the Nation's major energy-related environmental problems concerns the
need to control sulfur dioxide (SO2> emissions from stationary fuel combustion
sources. Recent EPA estimates place SOX emissions at about 26 to 30 million metric
tons per year(1). Most SOX emissions come from a relatively small variety of sources.
About 80 percent of all emissions are from stationary source fuel combustion and
about two-thirds of all emissions are from the electric utility industry. The remaining
20 percent can be primarily attributed to a few industrial processes: metals smelting
and refining, petroleum refining, minerals products processing, and chemicals manu-
facturing. Approximately 60 percent of the industrial emissions are attributable to the
metals industries with the remainder being divided somewhat evenly among the other
three areas.
The Clean Air Act as amended in 1977 includes a number of provisions relating
either directly or indirectly to the emission of sulfur oxides and other pollutants
including:
• National ambient air quality standards (NAAQS)
• Performance standards for new or modified stationary sources (NSPS)
• Prevention of significant air quality deterioration in areas cleaner than required
by Federal standards (PSD)
• Methods for cleaning up nonattainment areas
The states and municipalities may enact (and some have) regulations that are more
stringent than Federal laws and regulations.
49
-------
NEW SOURCE
PERFORMANCE STANDARDS
Federal emission limitations on sulfur dioxide were initially imposed on new
fossil fuel-fired steam generators by regulations promulgated on December 23, 1971.
These regulations apply to steam generators with a heat input of more than 73 MW
(250 million Btu/hr) and for which construction or modification was initiated after
August 17, 1971 (the date of proposal of the standards). The regulations limit emis-
sions to 520 ng/J (1.2 Ib/million Btu) heat input for solid fuels (e.g., coal) and 340
ng/J (0.8 Ib/million Btu) heat input for liquid fuels (e.g., oil). As an example, this
limitation requires removal of more than 70 percent of the sulfur dioxide emitted
when burning a coal containing 3 percent sulfur and having a heating value of 28,000
J/G (12,000 Btu/lb). These limitations apply to almost all utility boilers and some
large industrial boilers.
On June 11, 1979, EPA promulgated revised new source performance standards
for new or substantially modified steam generating units (fossil-fueled), having more
than 73 MW (250 million Btu/hr) heat input (2). These standards apply to any units
for which construction began after September 18, 1978. For other stationary sources,
performance standards are to be set by 1982 for all currently unregulated major source
categories. The law requires that all major stationary sources use the best available
control technology (BACT) to substantially reduce emissions. In the case of coal-fired
power plants, the law specifically defines BACT as the best continuous emission
control available. The use of dispersion methods (such as tall stacks and cutbacks in
operation during adverse weather conditions) alone instead of emission reduction
technology cannot be used as final compliance measures.
SOLID FUELS
The 1979 revised standards require that emissions for solids or solid derived fuels
(except solvent refined coal) be limited to 1.2 pounds of SO2 per million Btu heat
input. A 90-percent reduction is also required for (controlled) emissions between 0.6
and 1.2 pounds of S02 per million Btu. When SO2 emissions are 0.6 pounds per
million Btu, a 70-percent to 90-percent reduction in potential emissions is required.
A minimum of 70-percent reduction is required even if the (controlled) emissions
are less than 0.6. The percent reduction requirement is to be determined on a contin-
uous basis and will be based on a 30-day rolling average. The percent reduction is
computed on the basis of overall SO2 removal, including precombustion treatment
and removal of sulfur in the ash.
LIQUID FUELS
For gaseous and liquid fuels (not derived from solid fuels) the limits for S02
emissions are 0.8 pounds per million Btu heat input and 90 percent reduction in
potential emissions. The reduction requirement does not apply if SO2 emissions are
less than 0.2 pounds of SO2 per million Btu of heat input.
Anthracite coal is exempt from the percentage reduction requirement but is
subject to the maximum emission rate of 1.2 pounds of S02 per million Btu of heat
input. Other exemptions of various kinds apply to facilities in noncontinental U.S.
areas and to resource recovery facilities.
Solvent refined coal (SRC) is subject to the emission limit of 1.2 pounds of S02
per million Btu of heat input but requires only an 85-percent removal of S02 on a
24-hour per day basis. Commerical SRC demonstration plants will be permitted an 80-
percent removal requirement.
PREVENTION OF SIGNIFICANT
DETERIORATION
The 1977 amendments specified that sulfur oxides emissions cannot cause an
increase over an area's baseline concentration of sulfur oxides where the air is cleaner
than the ambient standards. A system of maximum allowable increases has been
established with the smallest increase allowed in Class 1 areas, more in Class II, and the
most in Class III; however, no area may exceed the national ambient standards. Manda-
tory Class I areas include those international parks, national memorial parks, and
national wilderness areas greater than 5,000 acres, and national parks of more than
6,000 acres in existence at the time of legislation. All other areas are initially desig-
nated Class II. Certain Federal areas may be redesignated Class I; states have the
authority to either upgrade other areas to Class I or downgrade them to Class III.
However, certain Federal areas of 10,000 acres or more may not be redesignated as
Class III. The law does not rule out growth in cleaner than standard areas but requires
50
-------
IMONATTAINMENT AREAS
major new sources to obtain a preconstruction permit, for which a modeling study
must be carried out at the applicant's expense, showing the projected impact of the
new source emissions on the air quality of the area.
For areas where ambient air quality exceeds the standards, the 1977 amendments
provide for an offset policy. Before new sources of emissions are permitted, action
must be taken to more than offset the new emissions by reducing existing ones. The
objective is to continue reducing a nonattainment area's emissions until standards are
achieved but to allow some growth of less polluting industries in the interim.
CONTROL OPTIONS
LOW SULFUR FUELS
As mandated by the Clean Air Act, EPA has also promulgated primary and
secondary national ambient air quality standards (NAAQS) for SC^. Primary standards
are designed to protect the public health and secondary standards are meant to protect
the public welfare. These standards are given in Table 1. Whereas the NSPS directly
limit emissions from certain new sources, the NAAQS indirectly control emissions from
TABLE 1
National Ambient Air Quality Standards for SO2
Annual Mean
Maximum 24-hour Concentration*
Primary
80 ,ug/m3
(0.03 ppm)
365 jug/m3
(0.14 ppm)
Secondary
-
-
Maximum 3-hour Concentration*
(0.5 ppm)
*l\lot to be exceeded more than once a year.
all sources. To meet the primary standards, the Clean Air Act amendments require
each state to adopt (and submit to the EPA Administrator) a State Implementation
Plan (SIP) to provide for implementation, maintenance, and enforcement of the
primary standard as soon as practicable but not later than 3 years from the date of
approval of the SIP Requirements of the SIP to implement, maintain, and enforce the
secondary standard must specify a reasonable time at which such secondary standard
will be attained. The Clean Air Act amendments of 1977 require review of the criteria
documents and NAAQS for sulfur oxides before 1980.
To control SOX emissions from combustion sources, one can:
• Use low sulfur fuels
• Remove sulfur from the fuel before combustion (coal cleaning and
fuel processing)
• Remove sulfur during combustion (fluid bed combustion [FBC] )
• Remove sulfur from the flue gases after combustion (flue gas desulfurization
[FGD])
• Combinations of the above
The use of naturally occurring low-sulfur coal is the most straight-forward
control option. However, projected production capacity is limited and most low sulfur
coal reserves are in the West, far away from Midwestern and Eastern requirements.
It has been estimated that low sulfur coal production will supply less than 44 percent
of the anticipated demand in 1980. Utilization of low sulfur coal east of the
Mississippi leads to substantial transportation costs, yielding overall power production
costs comparable to the use of FGD with local high sulfur coals. The recently revised
NSPS could essentially eliminate the clean coal option without FGD for new sources
since the best low sulfur coal can barely meet the 1971 NSPS.
51
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PHYSICAL COAL CLEANING
CHEMICAL COAL
CLEANING
FLUID BED COMBUSTION
FLUE GAS DESULFURIZATION
Techniques for removing sulfur from coal prior to combustion include physical
or chemical coal cleaning and the generation of clean synthetic fuels. The former deals
with removal of inorganic sulfur-containing matter (e.g., pyrite and sulfate) that is
physically associated with the coal. The latter deals with sulfur that is chemically
bound within the organic structure of the coal.
Physical coal cleaning (based on the difference in specific gravities or surface
properties of the inorganic matter and the remainder of the coal) has been in use for
years. From 20 percent to 80 percent of pyritic sulfur can be removed depending on
the coal and techniques used. It has been estimated that less than 13.5 percent of our
coal reserves can be physically cleaned to meet present NSPS. Obviously, in complying
with more stringent NSPS, physical coal cleaning must be used with FGD or in
combination with other controls. Currently, about 50 percent of the domestically
consumed coal is physically cleaned to remove mineral matter and mining residue. A
portion of the metallurgical grade coals is also cleaned to remove sulfur. Cleaning
operations for stem coals have not previously been designed and operated to remove
sulfur for compliance with SO2 emission regulations. The first U.S. steam coal prepar-
ation plant designed to remove sulfur for compliance with state and Federal S02
emission regulations has been operated at Homer City, Pennsylvania. Two other sulfur
removing plants are being planned by the Tennessee Valley Authority (TVA). None of
these steam coal plants incorporate the most advanced physical preparation techniques
now used in the metallurgical and mineral industries.
Chemical coal cleaning processes vary substantially because of the different
chemical reactions which can be used to remove sulfur and other contaminants from
coal. Chemical coal cleaning processes usually entail grinding the coal to small particles
and treating these particles with chemical agents at elevated temperatures and pres-
sures. The coal's sulfur is converted to elemental sulfur or sulfur compounds which can
be physically removed from the coal structure. Some chemical leaching processes, such
as the TRW-Meyers Process, remove only pyritic sulfur. Other less advanced processes,
such as that under development by the Department of Energy (DOE), are capable of
removing organic and pyritic sulfur. Chemical coal cleaning processes are currently
under development at the bench and pilot scales. Optimistically, several chemical
processes could be ready for commercial demonstration in 3 to 5 years.
Fluid bed combustion processes, both atmospheric and pressurized, remove sulfur
from coal during combustion by burning the coal in a fluidized bed of limestone or
dolomite. The sulfur in the coal reacts with the bed reagent to form dry calcium
sulfate. A portion of the fluid bed is continuously withdrawn to remove the sulfur
compounds either by direct disposal or by regeneration of the spent bed material.
These processes are currently at the pilot/prototype development stage and may reach
commercialization by 1985-1990. This technology may be suitable for new large utility
and industrial steam generators. One advantage over the nonregenerable wet scrubbing
FGD processes is that FBC processes produce a dry solid waste product rather than a
sludge. A process disadvantage is that fluid bed combustors require a much higher
consumption of limestone for the same amount of sulfur removal than does a wet
limestone FGD system. Consequently, the cost may in fact be higher than that for
FGD.
Application of FGD systems to large utility steam generators appears to be the
major near-term sulfur oxides control strategy. Flue gas desulfurization involves the
removal of sulfur oxides from combustion exhaust gases most commonly by chemical
reaction with an absorbent in aqueous slurry or solution in an absorption tower. The
tower is known as a scrubber, thus the common terminology, wet scrubbing. Basically,
a scrubber is a device in which gas/liquid contact occurs. Other FGD processes under
development remove the sulfur oxides by dry techniques, employing either reagent
injection into the boiler/flue gas or the use of spray dryers followed by fabric filters/
electrostatic precipitators. Application of FGD to utility boilers has increased dramat-
ically during the 1970's as can be seen in Figure 1. According to the latest EPA
survey, 162 utility boilers representing over 71,000 MW of electrical generating
capacity will have FGD systems by the late 1980's (3). A summary of the current
status of these systems is given in Table 2. As has been the case since the first U.S.
FGD systems were installed in the late 1960's, the ordering trend continues to heavily
favor wet lime/limestone systems which comprise approximately 90 percent of the
52
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TABLE 2
Number and Capacity of Utility FGD Systems
Status
Operational
Under Construction
Planned
Contract Awarded
Letter of Intent
Requesting/Evaluating Bids
Considering FGD Only
Total
Units
51
42
20
2
13
34
162
MW
17,822
15,763
10,517
1,100
9,110
17,174
71,486
52
48
40
o
£ 32
<
o
eo
ui
024
CO
CD
cc
LU 1C
a. lo
o
i T ii i i r
I I I I I
0
1968 69
i l i l i l i l l
71 73
79 81 83 85
75 77
YEAR
FIGURE 1-Projected FGD operating capacity, 1968 through 1986
53
-------
units in operation, under construction or planned. However, considerable interest has
surfaced within the utility industry with regard to dry scrubbing systems for low sulfur
coal applications which offer the potential for simplicity (hence improved reliability)
and lower costs. Three full-scale utility dry scrubbing systems are currently on order
with startup scheduled for mid-1981-1982.
The spectrum of FGD processes currently in operation in the U.S. for control
of SC>2 emissions from full-scale utility systems is shown in Table 3. These are sum-
marized by process type, number of systems, controlled generating capacity and
percentage of the total for each type.
TABLE 3
Operating Utility FGD Systems
Process
Dual Alkali
Limestone Slurry
Lime Slurry Scrubbing
Lime/Alkaline Fly Ash
Limestone/Alkaline Fly Ash
Soda Ash Solution
Magnesium Oxide
Wellman-Lord/Allied Chemical
Total
Tables 4 and 5 summarize
applications in the U.S. (4). Where
No. of
Units
2
21
18
1
2
3
1
3
51
the current
the utility
Controlled Capacity,
Generating % of
Capacity, MW Total
553 3
7386 42
6677 37
405 2
1480 8
375 2
120 1
826 5
17822 100
status of industrial boiler FGD
industry has leaned heavily toward
lime/limestone systems, the vast majority of industrial boiler FGD applications employ
nonregenerable sodium based systems.
TABLE 4
Number and Capacity of Industrial Boilers FGD Systems
Status
Operational
Under Construction
Planned
Contract Awarded
Letter of Intent
Requesting/Evaluation Bids
Considering FGD Only
Total
FGD
Systems
126
24
5
0
2
6
163
Capacity
Boilers Sites TO'3 SCFM
232 36 5,465
48 12 1,102
7 4 196
00 0
2 1 140
16 4 1,603
305 57 8,506
54
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TABLE 5
Summary of Operating Industrial Boiler
FGD Systems By Process Type
Process
Capacity, TO3 SCFM
Sodium Hydroxide/Sodium Carbonate
Dual Alkali
Limestone
Lime
Caustic Waste Stream
Ammonia
3,819
722
55
40
665
164
Total
5,465
THROWAWAY AND SALABLE
FGD PROCESSES
LIME/LIMESTONE
SLURRY SCRUBBING
The various FGD processes may be divided into two categories: regenerable and
nonregenerable (perhaps more properly into salable product and throwaway processes).
The regenerable or salable product processes produce sulfur, sulfuric acid, liquid SC>2
and possible gypsum if there is a market for it. (However, if impure gypsum is pro-
duced and is disposed of as solid waste, the system would be classified as throwaway.)
Throwaway or nonregenerable systems produce a liquid, solid, or sludge waste product
containing the sulfur removed from the flue gases. Of the systems appearing in Tables
3 and 5, only magnesium oxide and Wellman-Lord/Allied Chemical are salable product
processes.
It is interesting to note that, although only 2 percent of the utility systems (the
soda ash systems) produce a sizeable liquid waste stream, 83 percent of the nonutility
applications (soluble alkali, throwaway) produce such a stream. In general, disposal of
large volumes of liquid wastes containing soluble solids is environmentally unaccept-
able. Also, the cost of soluble alkali reagents is higher than calcium based alkali. In
most cases a permit for such operations must be secured from the appropriate regu-
latory authority. Since utility systems are generally larger than nonutility systems,
discharge permits for such operation may be less likely obtainable and reagent cost
considerations thus become more significant. Most soluble throwaway systems either
treat the soluble waste stream to reduce chemical oxygen demand (COD) and then
feed the waste through some municipal wastewater process or simply evaporate the
liquid.
Brief descriptions of most of the significant U.S. operating process types are
given below.
In concept, lime or limestone slurry scrubbing processes are very simple. In
practice, however, the chemistry and system design for a full-scale operation can be
more complex than seems evident at first glance. These systems use a slurry of lime or
limestone in water to absorb SO2 from power plant flue gas in a gas/liquid scrubber.
The slurry generally ranges from 5 percent to 15 percent solids. Various types of
scrubbers or gas/liquid contact devices are employed commercially: spray towers, grid
towers, plate towers, Venturis, marble-bed scrubbers (packed beds of glass spheres), and
turbulent-contact absorbers (lightweight hollow plastic spheres—ping-pong balls—held
between restraining grids in a countercurrent scrubbing tower). These scrubbers usually
operate with a liquid-to-gas (L/G) ratio of 6 to 15 1/normal m3 (40 to 100 gal/1,000
actual ft) (3).
The overall absorption reaction taking place in the scrubber and the hold-tanks
for a limestone slurry system produces hydrated calcium sulfite:
55
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ALKALINE FLY
ASH SCRUBBING
SODA ASH SCRUBBING
CaC03 + SO2 + 1/2 H20 * CaS03'1/2 H2O + CO2 (D
With a lime slurry system, the overall reaction is similar but yields no C02:
CaO + SO2 + 1/2 H2O > CaSO3'1/2 H20 (2)
(The actual reactant in Equation 2 is Ca(OH)2, since CaO is slaked in the slurrying
process.)
In practice, some of the absorbed SO2 is oxidized by oxygen which is also
absorbed from the flue gas. This shows up in the slurry as either gypsum
(CaSO4'2H2O) or as a calcium sulfite/sulfate mixed crystal [Ca(SO3)x(S04)y-z H20].
Slurry is recycled around the scrubber to obtain the high liquid-to-gas ratios required.
A bleed stream is taken from the scrubber liquid circuit to remove the calcium-sulfur
compounds formed. This is accomplished by thickening, filtration, ponding, and
various combinations of these operations. The calcium-sulfur compounds are solids to
be disposed; the liquor separated is usually recycled to the system.
Lime and limestone slurry scrubbing systems can be engineered for almost any
desired level of S02 removal. Present commercial utility systems are generally designed
for 80 percent to 90 percent removal; however, higher removals have been achieved.
The higher removal rate is not incrementally very costly: investment savings realized in
designing for 80 percent rather than 90 percent S02 removal amount to only about
3.2 percent to 4.5 percent(5).
Western U.S. low-sulfur coals appear particularly suitable to S02 control by
scrubbing the waste gases with a slurry of the alkaline fly ash which results from the
combustion process (6). There are two ways to add the alkaline ash to the system:
• Collecting the fly ash in an electrostatic precipitator upstream of the scrubber
and then slurrying the dry fly ash with water so that it can be pumped into the
scrubber circuit
• Scrubbing the fly ash directly from the flue gas by the circulating slurry of fly
ash and water
Most western coals have a low sulfur content (less than 1.0 percent). They also
usually have a low heating value and consequently require close control to hold their
combustion emissions within current Federal limits for NSPS defined as mass emissions
per unit heat input. Whereas typical eastern bituminous coals have heating values of
about 28,000 J/g (12,000 Btu/lb), lignite coals may have heating values as low as
16,000 J/g (6,800 Btu/lb). The bituminous coal could contain as much as 0.7 percent
sulfur and still meet the old NSPS limitation of 520 ng/J without controls, but the
lignite would have to have no more than about 0.4 percent sulfur due to its lower
heating value. Generally, the coals best suited to this method are the western lignites
and subbituminous coals. Certain of these coals (e.g., those from North Dakota,
Montana, and Wyoming) contain up to 20 percent ash; and the ash contains up to 40
percent alkaline constituents including oxides of calcium, magnesium, sodium, and
potassium, some of which are offset by acidic constituents. With the revised NSPS, this
process may, however, have to be used wth supplemental lime or limestone to meet
standards.
The soda ash scrubbing method of controlling S02 involves scrubbing the flue
gas with a solution of sodium carbonate and bicarbonate to produce a mixture of
sodium sulfite and sulfate by these reactions:
Na2C03 + S02 -> Na2SO3 + C02
(3)
2 NaHC03 + S02 + H2O * Na2SO3 + 2 H20 + CO2
(4)
Na2SO3 + 1/2 02 * Na2S04
(5)
56
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MAGNESIUM OXIDE
SCRUBBING
WELLMAN-LORD SYSTEM
The sodium carbonate does not have to be pure. Nevada Power Company uses trona
salt, a naturally occurring mineral containing 60 percent NaHCO3, 20 percent NaC1,
10 percent sulfates, and 10 percent insolubles. This process has definite limitations in
large-scale utility applications, since it requires a relatively cheap source of sodium
carbonate or bicarbonate and an ability to dispose of large volumes of waste salt
solution. Nevada Power is located near trona deposits—in an area where natural
evaporation rates far exceed rainfall and where land is relatively abundant. The
company processes its liquid waste in solar evaporation ponds and deposits the crystal-
lized waste salts back at the mine.
The magnesium oxide process is a regenerable or salable product process. It does
not produce waste material; SO2 removed from the flue gas is concentrated and used
to make marketable (^804 or elemental sulfur. Employing a slurry of MgO—or
Mg(OH>2—to absorb SO2 from flue gas in a scrubber, this process yields magnesium
sulfite and sulfate. When dried and calcined, the mixed sulfite/sulfate produces a
concentrated stream (10 percent to 15 percent) of SO2 and regenerates MgO for
recycle to the scrubber. Carbon added to the calcining step reduces any MgS04 to
MgO and SO2- In commercial applications, the scrubbing and drying steps would
normally take place at the power plant. The regeneration and 1^804 production steps
might be performed at a conventional sulfuric acid plant. Alternatively, a central
processing plant could produce sulfur from mixed magnesium sulfite/sulfate brought
in from several desulfurization locations.
The Wellman-Lord process is also a regenerable or salable product system. When
coupled with other processing steps, it can make salable liquid S02, ^804, or ele-
mental sulfur.
DUAL ALKALI
The Wellman-Lord process employs a solution of Na2SO3 to absorb SO2 from
waste gases in a scrubber or absorber, converting the sulfite to bisulfite:
NA2SO3 + SO2 + H2O * 2 NaHS03
(6)
Thermal decomposition of the bisulfite in an evaporative crystallizer regenerates
sodium sulfite for reuse as the absorbent:
2 NaHSO3 ^i Na2SO3 + SO2 + H2O
(7)
The evaporative crystallizer produces a mixture of steam and SO2 and a slurry con-
taining sodium sulfite/sulfate plus some undecomposed NaHSO3 in solution. As water
condenses from the steam/S02 mixture, it leaves a wet S02-enriched gas stream to
undergo further processing for recovery of salable sulfur values.
Most industrial boilers use a soluble alkali scrubbing process—basically as des-
cribed for soda ash scrubbing, and using sodium carbonate, bicarbonate, hydroxide,
or ammonia based alkali—which converts sulfur in the flue gas to sulfite/bisulfite and
sulfate in solution. Disposal practices for spent scrubbing liquors include consumption
in pulp/paper manufacturing, storage in evaporation ponds, and treatment (mainly
by air oxidation) and discharge to sewer system/waterways. Some sodium-alkali users
are considering regeneration of scrubber liquor by treating the spent liquor with
calcium hydroxide. This would actually give them dual alkali systems with the
attendant advantage of eliminating a liquid-waste stream.
Table 5 shows that dual alkali systems have become the second most prevalent
type of S02 control for industrial boilers. They may become the first choice as more
sodium alkali systems are converted to dual alkali in the face of new regulations that
may limit disposal of liquid wastes containing large amounts of dissolved salts. Dual
alkali processes, like lime/limestone slurry scrubbing, are throwaway systems. In the
operation as a whole, lime is consumed to produce a wet solid waste (mainly calcium
sulfite/sulfate) just as in lime slurry scrubbing. In addition, however, dual alkali sys-
tems require a small amount of sodium alkali makeup.
A solution of sodium sulfite/bisulfite and sulfate in a scrubber will absorb SO2
from the flue gas or other waste gas. Only the sulfite is active in absorbing S02,
forming bisulfite as in the Wellman-Lord system:
57
-------
Absorption: S03 + S02 + H2O * 2 HSO
(8)
The bisulfite-rich liquor, treated with lime in a reaction tank, regenerates active alkali
for recycle to the scrubber:
Regeneration: 2 HSO 3 + Ca(OH)2 * S03 + CaS03 4- + 2 H2O
SC>4 + Ca(OH)2 •> 2 OH ~ + CaS04 *
(9)
(10)
RD&D PROGRAM RESULTS
PROTOTYPE FACILITY
The sulfate and sulfite precipitate as a hydrated mixed crystal, or as a gypsum phase
(CaSG-4'2 H2O) plus a hydrated mixed crystal, depending upon the concentration of
dissolved species. Also, depending upon solution concentrations, the mixed crystal is
predominantly calcium sulfite, with up to about 25 percent calcium sulfate coprecipi-
tated. Sulfite/bisulfite oxidation by oxygen in the flue gas produces sulfate in the
system.
The 1970 and 1977 Amendments to the Clean Air Act provide the authority for
EPA's current research, development, and demonstration program in the FGD area.
EPA's FGD RD&D program is conducted by the Industrial Environmental Research
Laboratory at Research Triangle Park, N.C. (IERL-RTP). The primary purpose of this
program has been to improve, develop, and demonstrate reliable, cost-effective and
environmentally acceptable FGD processes for reducing SOX emissions from both
existing and new stationary combustion sources. EPA has been aided in this effort
by at least two other Federal organizations, the Tennessee Valley Authority (TVA) and
the U.S. Bureau of Mines (USBM). For example, EPA's key program in the nonregen-
erable area is the lime/limestone prototype test program at TVA's Shawnee Steam
Plant (near Paducah, Kentucky), and a major regenerable process (citrate)
demonstration unit is being built at a St. Joe Minerals plant based on pilot plant work
by USBM. In addition, the Department of Energy is expected to play a major role in
the FGD technology development area in the near future.
In the Federal Interagency Energy/Environment Research and Development
Program, FGD technology development has been given a high priority. Studies by EPA
indicate that FGD is competitive in cost with advanced control methods such as
chemical coal cleaning and fluidized bed combustion; therefore, FGD should play an
important role in controlling emissions at least until the end of the twentieth century.
FGD technology has progressed rapidly in part due to financial aid passing through the
Federal Interagency Program. A number of FGD supporting studies, pilot plants,
prototypes, and demonstration-scale facilities have been funded by EPA supplementing
progress in FGD development by the private sector. Some of the more significant
current Federal FGD programs are summarized below.
The focal point of EPA's lime/limestone development effort has involved the
operation of a prototype scrubbing test facility of TVA's Shawnee Steam Plant in
Paducah, Kentucky. This versatile facility allows comprehensive testing of three 10 MW
scrubber types under a variety of operating conditions and has been in operation sines
1972. Bechtel Corporation of San Francisco designed the test facility and directs the
test program. TVA constructed and operates the facility. Funding for the construction,
operating, and maintenance of the facility has been provided by EPA.
The major concerns of the utility industry to date regarding lime/limestone
scrubbing have centered on process reliability, the large quantities of waste sludge
generated, and the high costs (capital and operating) of scrubbing. It is toward these
areas of concern that the Shawnee program has been directed.
Major objectives of the original test program were:
• To characterize fully the effect of important process variables on S02 and
particulate matter removal
• To develop and verify mathematical models to allow scaleup to full-scale
scrubber facilities
58
-------
OBJECTIVES OF
SHAWNEE TEST PROGRAM
IN-HOUSE FGD PILOT
PLANT
BANCO SCRUBBER
• To study the technical and economic feasibility of lime/limestone scrubbing, and
• To demonstrate long-term reliability.
The Shawnee program was subsequently extended and the scope expanded to
investigate promising equipment and process variations to:
• Minimize costs, energy requirements, and quantity (and improve the quality) of
the sludge produced
• Maximize SC>2 removal efficiency
• Develop a design/economic study computer program, and
• Improve system control and operating reliability, especially in the mist eliminator
area.
Of particular interest have been studies of forced oxidation, increased alkali utilization,
MgO and organic acid additives to increase 862 removal efficiency and to force sub-
saturated gypsum operation.
The Shawnee program has made major contributions toward improvement of
lime and limestone scrubbing technology. Recent results are of particular importance
since over 90 percent of the approximately 75,000 MW of coal-fired electrical gener-
ating capacity in the U.S. presently committed to the use of FGD systems involve the
use of lime/limestone processes. These results have shown substantial improvements in
lime/limestone scrubbing systems in the areas of reliability, performance and waste
disposal. Limestone utilizations exceeding 90 percent have been achieved with both
single and double loop absorbers, thus reducing the limestone required and the calcium
sulfite waste material produced for disposal. Forced oxidation of the calcium sulfite
waste to calcium sulfate (gypsum) has been successfully demonstrated, enabling sub-
stantial reductions in the volume of waste produced and improvements in its disposal
properties(7,8). Finally, the use of additives such as soluble alkalis or buffering acids
(such as adipic acid) has been shown to dramatically enhance the mass transfer charac-
teristics of limestone scrubbers and hence, enable attainment of SO2 removal effi-
ciencies exceeding 95 percent(9).
The EPA FGD pilot plant operated at IERL-RTP consists of two scrubbers
having a flue gas capacity of about 0.1 MW. They have been in operation since 1972
to provide in-house experimental support for EPA's larger, prototype scrubber test
facility at the Shawnee Steam Plant. The IERL-RTP scrubbers have 1 percent of the
capacity of the Shawnee prototypes and are 1/1000 the size of a full-scale utility
system. In addition to supporting Shawnee, the pilot plant also provides IERL-RTP
with the capacity to independently evaluate new concepts in lime/limestone scrubbing
technology. Many of the new concepts tested at Shawnee (such as forced oxidation
and adipic acid additives) were first conceptualized and developed in the IERL-RTP
pilot plant(10,11,12).
The feasibility of replacing freshwater makeup for limestone FGD systems with
cooling tower or boiler blowdown has recently been established in the IERL-RTP pilot
plant and operating limits defined(13). Further refinement of this development should
make possible the integration of water treatment processes with FGD systems using
forced oxidation. Such systems will maximize water reuse and minimize soluble salt
discharges.
One of the pilot plant scrubbers was recently modified to allow testing of dual
alkali systems with either lime or limestone regeneration. This will permit the in-house
pilot plant to support EPA's development and demonstration efforts in dual alkali
technology as it has supported the lime/limestone program in the past.
EPA recently completed an 18-month test program at a lime/limestone industrial
boiler FGD system installed to control SO2 and particle emissions from seven small
coal-fired heating boilers (approximately 23 MW equivalent, total) at the Richenbacker
59
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FULL-SCALE DUAL
ALKALI DEMONSTRATION
WELLMAN-LORD/ALLIED
CHEMICAL DEMONSTRATION
Air Force Base near Columbus, Ohio. The FGD system was installed under contract
between the Air Force and Research Cottrell, the U.S. licensee for the A. B. Bahco
lime/limestone scrubbing process. This process was developed by A. B. Bahco, a
Swedish company, and appears to be particularly well suited for industrial boiler
applications in that it is manufactured in standard sizes in the range of 5-50 MW
equivalent and is adaptable to a high degree of automation. The application of the
Bahco scrubber at Rickenbacker was the first such installation in the U.S. and the first
shutdown in September, a new baseline test was completed and the demonstration
testing was reinitiated; the system has been in operation since that time. The integrated
system is consistently achieving 91 percent S02 removal, particulate emissions of 0.04
lb/10^ Btu, and a sulfur product of 99.9 percent purity; sodium carbonate makeup
anywhere on a coal-fired industrial boiler. The system met or exceeded all emission
and operating cost guarantees. A final report on this program is currently available(14).
Additional EPA-sponsored work conducted at the site involved the evaluation of
lime sludge (a waste product from water treatment plants) as an alternate S02 removal
reagent. Results of the experimental program demonstrated that lime sludge is effective
and offers significant cost savings over conventional lime/limestone reagents. Since lime
sludge is widely available in many midwestern states where high sulfur coal is exten-
sively used, it could find application for industrial boilers. A report describing these
results will be published in November 1979.
In September 1976, EPA contracted with Louisville Gas and Electric (LG&E) for
a cost-shared, full-scale coal-fired utility demonstration of the dual alkali process at the
280 MW Cane Run No. 6 boiler. The demonstration project consists of four phases:
• Design and cost estimation
• Engineering design, construction, and mechanical testing
• Startup and performance testing
year of operation and long-term testing
Construction was completed in April 1979 and startup operations are currently under
way. Phase 4 is expected to begin in November 1979. The FGD system was designed
by Combustion Equipment Associates and Arthur D. Little, Inc. and was constructed
by LG&E. In June 1977 a contract was established with Bechtel National, Inc. to
design and conduct a test program to evaluate the system installed at LG&E. A report
on the Phase 1 preliminary design and cost estimate for the system has been pub-
lished(15). In addition to the design and cost estimate for the LG&E system, it also
gives cost projections for similar hypothetical systems in the 500 and 1000 MW range.
The report projects the LG&E system costs at less than $60/kW capital cost and less
than 3 mills/kWhr annualized operating costs in 1976 dollars.
EPA and Northern Indiana Public Service Company (NIPSCO) have jointly
funded the design and construction of an FGD demonstration plant using the
Wellman-Lord SO2 recovery process and the Allied Chemical SO2 reduction process to
convert recovered S02 to elemental sulfur. The operational costs for the system are
being paid by NIPSCO, and a comprehensive test and evaluation program, conducted
by TRW Corporation, has been funded by EPA. The demonstration system has been
retrofitted to the 115 MW coal-fired unit 11 at the D.H. Mitchell Station in Gary,
Indiana.
The demonstration program consists of the following phases: Phase l-the devel-
opment of a process design, major equipment specification and a detailed cost
estimate-was completed in December 1972. Phase I l-the final design and con-
struction—was completed by Davy Powergas, Inc. in August 1976.
Since the completion of startup activities, the plant has been operated by Allied
Chemical under contract with NIPSCO. During the demonstration, a comprehensive
test and evaluation program is being carried out by TRW, under contract with
IERL-RTP. Integrated operation was achieved in August 1977, at which time the
60
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AQUEOUS CARBONATE
DEMONSTRATION
CITRATE DEMONSTRATION
PROGRAM
DRY SO2 CONTROL
PROGRAM
Acceptance Test was successfully completed(16). The demonstration test year began
in September 1977 but boiler and interface problems prevented acceptable operations
until August 1978, after which 40 days of successful integrated operations were com-
pleted. Following system modification and maintenance during the scheduled boiler
and utilities costs are within design targets. The FGD plant is following normal boiler
operation (startup, shutdown, load changes, fuel changes, etc.) during the demonstra-
tion. The primary concern during the testing is the collection and evaluation of per-
formance and economic data. TRW has prepared an interim report which presents the
data collected over the first year of testing(17). A second, final, report will be
prepared at the end of the second year of testing.
EPA, EPRI, DOE and Empire State Electric Energy Research Corporation
(ESEERCO), a research organization sponsored by New York's eight major power
suppliers, have contracted to fund jointly the design and construction of a demonstra-
tion of Atomics International's sulfur-producing aqueous carbonate process) 18). The
demonstration is being retrofitted to a 100 MW boiler at Niagara Mohawk Power
Company's coal-fired Huntley Station in Tonawanda, New York.
The demonstration is in four phases. Phase I, the design and cost estimate,
was completed in May 1977. Phase II, construction, is expected to be completed by
mid-1982. Phase III, acceptance testing, and Phase IV, an 18-month demonstration
testing period, will follow.
EPA and U. S. Bureau of Mines (USBM) have entered into a cooperative agree-
ment to pool funds and technical talents to demonstrate the citrate process, a regener-
able sulfur producing process, which has been developed through pilot scale by USBM.
A concurrent development program, carried out by an industrial consortium headed
by Pfizer Chemical Company, also led to a pilot operation of the process. Based on the
results of these two pilot programs, EPA and USBM have initiated the demonstration
of this technology on a 50 MW coal-fired boiler at St. Joe Minerals Corporation in
Monaca, Pennsylvania(19).
The demonstration is in four phases. Phase I, the design and cost estimate,
was completed in November 1976. Phase II, detailed design, procurement, and con-
struction, began in March 1977 and was completed in July 1979. Acceptance testing,
Phase III, should be accomplished in October 1979 at which time a 1-year test and
evaluation program, Phase IV, will be initiated.
IERL-RTP accelerated its dry S02 control program early in 1979 through
support of two surveys. One survey concerns the economics of dry scrubbing and is
being performed by TV A. The initial objective of this study is to provide an expedi-
tious economic comparison of the most promising application of a lime sorbent dry
scrubbing system treating flue gas from western coal (0.7 percent sulfur, high
alkalinity) with state-of-the-art wet limestone scrubbing. The report on this objective
is slated for mid-August 1979 and will serve as an interim in-house reference. The final
report, which is to be prepared by TVA in mid-1980, will include process information
from vendors and cover the three methods of dry FGD technology—spray dryer-
baghouse, dry sorbent duct injection (prior to baghouse), and dry sorbent boiler
injection—limestone injection via low NOX burner. The second survey serves to sum-
marize the status of dry FGD processes in the United States for both utility and
industrial applications. The Radian Corporation has completed a draft report which is
now undergoing EPA's review. Publication of this state-of-the-art report is expected
by mid-October 1979. Quarterly updates of this survey for this rapidly developing
technology field are planned during FY 80.
Three EPA-sponsored demonstrations of dry FGD systems are in the planning
stages with three different vendors. One demonstration would involve a full-scale
industrial-size boiler (100,000 Ib steam/hr), using Eastern coal (1-2 percent sulfur)
and a spray dryer-baghouse system with lime as sorbent. This system at Celanese's
Amcelle Plant (Cumberland, Maryland) is under construction and is expected to be
operational in March 1980. These tests are expected to provide data relevant to estab-
lishing NSPS for industrial boilers.
61
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OTHER FGD SUPPORT PROJECTS
Two pilot-scale projects at Western utilities are under consideration. Both would
involve spray dryer-baghouse systems and scrubber waste characterization. However, a
sodium compound (nahcolite) would be a sorbent at one site where evaluation of dry
sorbent injection as an S02 removal method is also an objective. At the second site,
comprehensive testing over 6 months of a system using lime as sorbent in a system
handling 5,000 to 10,000 acfm of flue gas is planned.
If plans materialize, the full-load data for the full-scale industrial boiler scrubber
tests should be available by June 1980, and the final report should be completed in
September 1980. Reports for the two pilot demonstrations at utility sites are expected
to be completed by the fall of 1981.
In addition to the current pilot and demonstration programs, previously dis-
cussed, oLher EPA-funded support activities in the FGD area include design and cost
evaluations for advanced S02 removal technologies, byproduct marketing studies,
bench-scale research on key processing steps, investigation of reductants for S02 to
sulfur, energy optimization studies, and an assessment of flue gas reheat needs. To
complement these control technology development efforts, companion technology
transfer efforts are also under way. Through a series of briefings, symposia, capsule
reports, summary reports, and a survey of FGD installations, the industry is being
aided in its efforts to stay abreast of the rapidly advancing FGD technology. These
technology transfer efforts include reporting the status of the many full-scale ultility
and industrial FGD systems designed, constructed and operated under private funding.
The use of high-sulfur coal will likely continue to increase in the coming years as
a result of the Administration's National Energy Plan. The application of FGD tech-
nology to both utility and industrial combustion sources is playing (and will continue
to play) a critical role in enabling these sources to comply with provisions of the
Clean Air Act.
The Federal Interagency FGD program participants have effectively worked with
industry to further the development, demonstration, and appreciation of FGD tech-
nology. Utility application of FGD systems now includes over 70,000 MW of capacity
either in operation, under construction or planned. This represents an increase of 27
percent over the preceding year.
62
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Michael D Shapiro
FOSSIL ENERGY
CLEANUP PROGRAM
TECHNOLOGY PROGRAM
AREAS
Mr. Shapiro:
The Fossil Energy Cleanup Technology Program is a relatively new part of the
overall fossil energy research program, initiated this fiscal year. It is, nevertheless,
an integral part of DOE's coal strategy, providing a critical link between the national
goal to use more coal and the simultaneous maintenance of a healthy environment.
A major DOE objective is to continue to expand U.S. coal use by continuing
present uses and ensuring that coal is a viable option for all new industrial and utility
uses. Meeting this objective is not only an obvious adjunct to reducing dependence on
oil imports, but a legal mandate established by this administration and the Congress
through national energy legislation, primarily the Power Plant and Industrial Fuel
Use Act. In the short term (between now and 1990), the primary mode of continued
and expanded coal use is in direct combustion applications. Direct firing of power
plants, boilers, and furnaces will account for 90 percent of total coal use in this
period.
The level of coal use is contingent on favorable economics, good technical
performance, and compliance with environmental limitations. In fact, only with
environmental compliance will expanded coal use be acceptable in the United States.
This is reflected not only in the permitting mechanisms established in the major
environmental laws, but also in the implementing legislation for DOE's coal conversion
program, where exemptions allowing oil and gas use can be issued because of technical
inadequacies or the high costs of pollution control systems.
Coal use is controlled under several major environmental laws. Of primary
importance is the Clean Air Act. The environmental performance required for both
utility and industrial coal-burning facilities depends on the age and location of the
facility. Most existing facilities must meet the emission limitations in the Clean Air
Act's State Implementation Plans (SIPs). New facilities that commence construction
before proposal of EPA's revised New Source Performance Standards (NSPS) must
meet the current NSPS. However, future coal use will be increasingly affected by the
stricter standards in upcoming NSPS revisions. All of this leads to a significant
demand for control of air emissions associated with coal use. Several other Federal
laws, aimed at toxics in drinking water, general waterways, and waste disposal, regulate
solid waste and water discharge from coal facilities. To date, these laws have not had
a major impact on coal-use economics, but EPA progress over the next several years
will result in clearer and stricter requirements in these areas.
With these short-term and long-term pollution control needs in mind, an inte-
grated Fossil Energy Cleanup Technology Program has been established. The goals
of this program are to identify, research, develop, refine, and demonstrate a range of
engineering approaches capable of the following:
• Removing flue gas pollutants for compliance with environmental standards.
• Removing undesirable components from process streams produced during gasi-
fication and/or combustion, thus protecting utilization equipment, such as
turbines, fuel cells, and heat exchangers.
The DOE's overall fossil fuels program, focused on the removal of contaminants
and pollutants, can be carried out before fuel use, during processing, and after com-
bustion. The cleanup technology program covers only the last two areas, which use
similar hardware and processes. These areas of activity are shown shaded in Figure 2.
Other parts of the overall energy system are treated elsewhere, all fitting together in a
systematic effort to advance and refine all practical methods of clean and inexpensive
fossil fuel use. Selection of the optimal path is a case-by-case decision related to
specific sites, fuel prices, energy needs, and regulations.
The technology program is organized into three areas:
• Flue gas cleanup
• Gas stream cleanup
• Technology support
63
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FOSSIL
FUEL
CLEAN LIQUID
FUEL
CONVENTIONAL
COAL
COMBUSTION
FLUIDIZED-BED
_ __ __ ^_ __ —
PFB
/GAS STREAM/
/ CLEANUP /
///////////////
//////////////
/GAS STREAM/
/ CLEANUP X
//////////////
»-
COMBUSTION
TURBINE
HEAT
EXCHANGER
TURBINE
COMBUS-
1TION,
TURBINE,
FUEL CELL
— k.
"••V
*
CO
<
U
_i
U-
w
^^ A FLUE GAS A ,^^c*
// CLEANUP // ^^1
'{(//"{(//it m
UI
_i
fe ^
z
o
u
FIGURE Z—Cleanup technology control optics
PROGRAM COSTS
Flue gas cleanup addresses the removal of air pollutants from the stack gases of
conventional combustion units to meet environmental standards. Efforts focus on
improving and demonstrating the reliability of conventional lime/limestone scrubbers,
developing second-generation flue gas desulfurization (FGD) technologies that avoid
wet sludge disposal, and initiating advanced technologies for removal of NOX partic-
ipates, and heavy metals. Gas stream cleanup includes the technology for removal of
contaminants during combustion process or from the process stream prior to utiliza-
tion. The key concerns are downstream hardware and environmental protection.
Primary emphasis is on developing technologies to clean gas streams produced by coal
gasifiers or fluidized bed combustors used in gas turbines, fuel cells, and heat ex-
changers. The objective is to remove sulfur compounds, particulates, and alkali metals.
Technology support develops the crosscutting technologies in waste management,
instrumentation and process controls, innovative concepts, and systems and economic
comparisons, supporting both the flue gas and gas stream cleanup efforts.
The funds appropriated for FY 1979 and the President's request for FY 1980 are
shown in Figure 3. Of the $7 million, $2.7 million has been budgeted for the flue gas
cleanup program for FY 1979. In addition, about half of the technology support
budget is directly associated with flue gas cleanup problems, so the total budget related
to flue gas cleanup is about $4 million. In FY 1980, $25.05 million, plus half of the
technology support funds, for a total of $28.55 million, has been requested for flue
gas cleanup.
The first project in flue gas cleanup is to demonstrate the full-scale reliability of
lime/limestone systems at acceptable cost. Our efforts to increase the reliability and
reduce the costs of existing lime/limestone systems have many facets. In the area of
erosion and corrosion, a cause of many failures, we will gather information on the
properties of materials that affect the rate of erosion and corrosion. Any gaps will be
filled using advanced instrumentation on existing test facilities, including the three
10-Mw units at TVA's Shawnee plant and the one at the Grand Forks Energy Tech-
nology Center.
64
-------
Funding ($ Millions)
Total
FY78
FY79
0
7.0
FY80
Flue Gas Cleanup
Gas Stream Cleanup
Technology Support
Capital Equipment
2.7
NO "2 4
PRIOR
FUNDING 1.9
0
25.05
10.4
7.0
0.8
43.25
ADVANCED FGD
PROJECT
PROPOSED PROCESSES
FIGURE 3—Fossil energy cleanup technology budget summary
Process chemistry influences scaling, plugging, and overall removal efficiency. To
understand these phenomena better, all existing data will be compiled and data gaps
filled through parametric analyses at existing test units. The effectiveness of additives
to control process chemistry will be tested for a range of coals, and the cost effective-
ness of their use will be determined. In related research, forced oxidation of sludge
and closed-loop operations will be field tested for their effectiveness in reducing the
potential wastewater and solid waste impacts. Automated control systems, in concert
with accurate process monitoring systems, promise real potential to both reduce costs
and improve performance of the scrubbing system. Both the development and the
testing of such systems will be supported.
To communicate the results of DOE's efforts to the persons designing, construc-
ting, and operating lime/limestone scrubbers, DOE, in conjunction with the Electric
Power Research Institute (EPRI), will produce a design manual for new systems and a
maintenance guide for existing units. The design manual will help prospective FGD
users select the best system as a function of size, coal type, applicable standards, and
resource costs for the site in question. The maintenance guide will specify regular
testing and/or maintenance activities to reduce the frequency of unplanned shutdown
due to component failure, plugging, or scaling. In all of these work areas, when a
significant improvement has been identified, DOE will support cost-shared evaluation
of the innovation at a full-scale utility module.
Lime/limestone systems essentially trade air pollution for solid waste pollution
problems. In the advanced FGD project we hope to develop smaller, cheaper, less
energy-consuming systems that minimize solid waste problems. A large number of
processes have been proposed, many of which are sufficiently developed to permit a
narrowing of choices for application from early 1982 through 1985. The processes are
grouped as follows:
• Dry process nonregenerable
• Double alkali process - nonregenerable
• All regenerable processes
The dry processes, including sorbent injection, use limestone, nahcolite, trona, or
the high alkali fly ash found in many western coals. The primary advantages of these
systems are simplicity and reliability. Although they are not regenerable, the waste
produced is a dry, more stable solid that does not require slurry ponds. The double
alkali process, in which the S02 removal is done separately from the production of
calcium sulfate sludge, can eliminate plugging and fouling problems and produce a
more stable waste. Regenerable systems, wet and dry, produce a potentially saleable
byproduct, such as elemental sulfur or sulfuric acid, but require a reducing agent, such
as natural or coal-derived gas. The regenerable aqueous carbonate, Wellman-Lord, and
magnesium oxide processes, for example, promise negligible secondary waste generation
and are, therefore, very attractive long-term options.
65
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ADVANCED CLEANUP
PROGRAM TARGETS
INTERAGENCY ACTIONS
JOINT EFFORTS
As our efforts on lime/limestone reliability are completed, process parameters of
advanced FGD systems will be investigated using the 10-Mw scrubbers at Shawnee and
Grand Forks. The target of the advanced flue gas cleanup effort is greater control of
the total spectrum of pollutants, with technologies available at acceptable costs by
1990.
For particulates, the focus is on improving conventional systems—electrostatic
precipitators and fabric filters—to increase their efficiency in fine-particle control and
to modify them for use under more rigorous conditions. Nitrogen oxide research
emphasizes the evaluation of ammonia reduction and integrated systems that remove
both sulfur and nitrogen oxides. The final element of the advanced cleanup program is
examining the potential for exhaust emissions control for stationary engines, such as
turbines and diesels, operating on high sulfur oil, coal liquids, or coal. We will
examine the environmental impacts of such sources, if uncontrolled, and identify
additional work needed.
There have been several recent interactions between DOE's Office of Fossil
Energy and EPA's Office of Energy, Minerals and Industry. We have signed an inter-
agency agreement for the transfer of funds between the agencies. It allows for direct
funding through EPA and also for joint funding of projects. In addition, we have
prepared a cooperative planning document. The document includes a background
describing the need for cooperation, the objectives of cooperation, the scope of the
arrangement, the strategy for joint efforts, and management control plans.
The joint goals and objectives are to support the increased use of coal, as speci-
fied in the National Energy Act; to ensure that coal is managed in a manner that
will protect public health and the environment; to improve the reliability and per-
formance of available environmental control technologies for use by the electric
utilities and industry; to minimize the capital and annual costs associated with environ-
mental control; and to develop and demonstrate methods of disposing of or using solid
waste created by coal use. Project areas included under the cooperative arrangement
are SOX control, both flue gas clean up and coal preparation; NOX control, including
flue gas treatment and combustion modification; particulate and contaminant control;
waste management; and system optimization, which includes the combined control
processes and supporting technologies.
Strategy for the joint efforts includes separate funding and transfer of funds
between the two agencies, technology transfer, joint cooperation on steering com-
mittees, and cost sharing of projects. In addition, to accomplish our goals, we must
work very closely with EPRI, TVA, the utilities, and private industry.
66
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References
1. National Air Quality and Emissions Trends Report, 1976. EPA-450/1 -77-002
(NTIS No. PB279007), December 1977.
2. Federal Register, Part II, "New Stationary Sources Performance Standards;
Electric Utility Steam Generating Units," pp. 33580-33624, June 11, 1979.
3. Smith, M., et al. EPA Utility FGD Survey: February-March 1979. EPA-600/7-
79-022d.
4. Tuttle, J., et al. EPA Industrial Boiler FGD Survey: First Quarter 1979. EPA-
600/7-79-067b, April 1979.
5. Slack, A.V., and G.A. Hollinden, 1975. Sulfur Dioxide Removal From Waste
Gases, 2nd Ed., p. 137, Noyes Data Corporation, Park Ridge, New Jersey.
6. Ness, H.N., et al. "Power Plant Flue Gas Desulfurization Using Alkaline Fly
Ash From Western Coals," Proceedings: Symposium on Flue Gas Desulfuri-
zation, March 1979, Volume I. EPA-600/7-79-167.
7. Head, H.N., et al. "Results of Lime and Limestone Testing With Forced Oxida-
tion at the EPA Alkali Scrubbing Test Facility," Proceedings: Symposium on
Flue Gas Desulfurization-Hollywood, FL 1977, Volume I. EPA-600/7-78-058a,
pp. 170-204, March 1978.
8. Head, H.N., et al. "Results of Lime and Limestone Testing With Forced Oxida-
tion at the EPA Alkali Scrubbing Test Facility—Second Report," Proceedings:
Industry Briefing on EPA Lime/Limestone Wet Scrubbing Test Programs. EPA-
600/7-79-092, March 1979.
9. Head, H.N., et al. "Recent Results From EPA's Lime/Limestone Wet Scrubbing
Programs—Adipic Acid as a Scrubber Additive," Proceedings: Symposium on Flue
Gas Desulfurization, March 1979, Volume I. EPA-600/7-79-167.
10. Borgwardt, R.H. "IERL-RTP Scrubber Studies Related to Forced Oxidation,"
Proceedings: Symposium on Flue Gas Desulfurization, New Orleans, LA, March
1976, Volume I, pp. 117-144. EPA-600/2-76-136a.
11. Borgwardt, R.H. "Effect of Forced Oxidation on Limestone/SOx Scrubber
Performance," Proceedings: Symposium on Flue Gas Desulfurization, Hollywood,
FL, November 1977, Volume I, pp. 205-228. EPA-600/7-78-058a.
12. Borgwardt, R.H. "Significant EPA/IERL-RTP Pilot Plant Results," Proceed-
ings: Industry Briefing on EPA Lime/Limestone Wet Scrubbing Test Programs,
pp. 1-9. EPA-600/7-79-092, March 1979.
13. Borgwardt, R.H. "Combined Flue Gas Desulfurization and Water Treatment
in Coal-Fired Power Plants." Paper submitted for publication to Environmental
Science and Technology, July 1979.
14. Biedell, E.L., et al. EPA Evaluation of Bahco Industrial Boiler Scrubber at
Rickenbacker AFB. EPA-600/7-78-115, June 1978.
15. Van Ness, et al. Project Manual for Full-Scale Dual Alkali Demonstration at
Louisville Gas and Electric Co.—Preliminary Design and Cost Estimate. EPA-
600/7-78-010, January 1978.
16. Adams, R.C., et al. Demonstration of Wellman-Lord/Allied Chemical FGD
Technology: Acceptance Test Results. EPA-600/7-79-014a.
67
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17. Adams, R.C., et al. Demonstration of Wellman-Lord/Allied Chemical FGD
Technology: Demonstration Test First Year Results. EPA-600/7-79-014b,
September 1979.
18. Binns, D.R., and R.G. Aldrich. "Design of the 100 MW Atomics International
Aqueous Carbonate Process Regeneration FGD Demonstration Plant," Proceed-
ings: Symposium on Flue Gas Desulfurization, March 1979. EPA-600/7-79-167.
19. Madenburg, R.S., et al. "Citrate Process Demonstration Plant—Construction
and Testing," Proceedings: Symposium on Flue Gas Desulfurization, March
1979. EPA-600/7-79-167.
68
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! I
NITROGEN OXIDES CONTROL
George Blair Martin
Joshua S. Bowen, D. Eng.
Industrial Environmental Research Laboratory/RTP
U.S. Environmental Protection Agency
George Blair Martin
CLEAN AIR ACT
OF 1970
CLEAN AIR ACT
AMENDMENTS
Nitrogen oxides (NOX), principally nitric oxide (NO) and nitrogen dioxide
(N02>, are atmospheric pollutants having the potential for direct and indirect adverse
effects on human health and welfare. Human activity originates emissions, resulting in
NOX concentrations in urban atmospheres that are 10 to 100 times higher than those
from natural sources in nonurban areas. Fuel combustion in equipment contributes
about 99 percent of technology-associated NOX emissions. For most equipment about
95 percent of the NOX is emitted as NO and 5 percent as NO2. In the atmosphere,
NOX enters into complex photochemical reactions with hydrocarbons and sulfur oxides
and results in the formation of undesirable secondary species, with a shift of residual
NO to NO2.
The adverse effects of NO2 and other pollutants on humans, animals, vegetation,
and exposed materials were among the factors which led to passage of the Clean Air
Act of 1970. With respect to NOX, this Act empowered the EPA (a) to establish
primary and secondary National Ambient Air Quality Standards (NAAQS) for N02,
(b) to require a 90 percent reduction in NOX emissions from light duty motor vehicles,
(c) to establish New Source Performance Standards (NSPS) for stationary sources, (d)
to set up mechanisms to ensure compliance and enforcement, and (e) to provide
research, development, and demonstrations of new and improved, commercially viable
methods for the prevention and control of pollution from the combgstion of fuels.
The Clean Air Act Amendments of 1977 require EPA (a) to revise the NAAQS
for N02 to consider short term effects (not more than 3 hours), (b) to implement a
revised level of automotive NOX control, (c) to require NSPS based on use of the best
technological continuous controls, and (d) to promulgate regulations for prevention of
significant deterioration of air quality. The Amendments also require that any conver-
sion of sources to coal firing be environmentally acceptable.
69
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TABLE 1
Major sources of NO
Source
Percent of Stationary
Source NO..
Utility Boilers — Coal
Utility Boilers — Oil and Gas
Packaged Boilers — Oil and Gas
Packaged Boilers — Coal
Warm Air Furnaces — Oil and Gas
Engines
Miscellaneous Sources
31.2
14.7
15.0
5.9
2.7
21.1
9.4
TABLE 2
New source performance standards for steam generators
NSPS (NO as NO2)
Fuel
ng NOX/J
IbNOJKTBtu
X
Coal
Bituminous
Subbituminous
257
214
Lignite
Pulverized Fired 257
Cyclone Fired 343
Coal Derived Liquids 214
Oil 129
Gas 86
0.6
0.5
0.6
0.8
0.5
0.3
0.2
POLLUTANT FORMATION
There are two areas under consideration for new or revised NSPS for steam
generators. First, the available data are being reviewed to identify demonstrated
technology for industrial boilers (less than 73 MW thermal, but greater than a not-yet-
established lower limit). NSPS for both gas turbine and reciprocating engines are also
being prepared. The gas turbine standard has been proposed at 75 ppm (at 15 percent
02> for nitrogen-free fuels, with a stepped approach for fuel nitrogen up to a
maximum of 125 ppm (at 15 percent ©2) for fuels with over 0.25 percent nitrogen.
The primary emphasis in EPA's NOX technology development program is on
combustion modification to prevent pollutant formation. To optimize the control
technology for any given fuel, it is necessary to understand the mechanisms by which
NOX is formed and destroyed during combustion. Two distinct sources of NOX,
identified by the terms thermal NOX and fuel NOX, are discussed below. In addition, it
70
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REGULATIONS
STANDARDS
FOR NEW SOURCES
PENDING REGULATIONS
This section of the paper provides information on combustion-generated NOX
which is necessary for a complete understanding of the EPA NOX control program.
In the United States in 1976, NOX emissions from human activity were estimated
to be about 24.7 million metric tons per year. Of this amount, 45.0 percent was
estimated to come from mobile sources, 51.7 percent from stationary combustion
sources, and the remainder from miscellaneous sources. The stationary source NOX can
be subdivided by the type of source and fuel burned to give a better picture of the
complexity of the problem. Table 1 represents the major divisions, but each source can
be further subdivided by equipment design.
Existing regulations for NOX fall into three categories: (a) ambient air quality
standards, (b) stationary new source performance standards, and (c) mobile source
standards.
To provide a basis for ambient air quality standards, available information was
compiled and analyzed by an advisory committee. The areas covered included not
only atmospheric chemistry, but also effects on materials, plants, and humans. A major
conclusion was that the ambient concentration of N02 should be used as the basis of
the standards. This was based on two main points. First, NO is rapidly converted to
NO2 in the atmosphere and, second, toxicology studies of NO and N02 show that
N02 is the more hazardous form at concentrations found in the atmosphere.
As required by the Clean Air Act of 1970, National Ambient Air Quality Stan-
dards (NAAQS) for N02 were set in 1971. The primary standard is based on a level
required to protect public health and the secondary standard protects the public
welfare from any known or anticipated adverse effect associated with the presence of
air pollutants in the ambient air. Both standards were set at 100 jug/m3 for NO2-
The Clean Air Act of 1970 required the EPA Administrator to set standards for
new sources. The only source category for which Federal New Source Performance
Standards (NSPS) are in effect is steam generators with a thermal input greater than 73
MW (250 X 106 Btu/hr). The initial NSPS for this class of equipment burning gas, oil,
and coal (except lignite) became effective in 1971. The coal standards were revised in
1979 and a coal-derived liquids standard was added. The lignite standard, which was
promulgated in 1978, is based on firing method; however, cyclone-fired boilers are
only allowed for fuel containing greater than 25 percent lignite from North Dakota,
South Dakota, or Montana. The NSPS are summarized in Table 2.
The basis of these regulations is combustion modification to reduce NOX
formation, and compliance is achieved with flue gas recirculation, staged combus-
tion and/or altered burner designs.
Although the NOX control strategy in the Clean Air Act of 1970 was predicated
primarily on high level control standards for the automobile, the 1977 Amendments
have eased the restrictions. The original standard of 0.24 mg/m (0.4g/mile) for 1978
has been retained only as a research goal. This relaxation of the automotive standard
places increased emphasis on control of stationary source NOX emissions. From the
current standard of 1.9 mg/m (3.2 g/mile), the standard is reduced to 1.2 mg/m (2.0
g/mile) through the 1980 model year, and to 0.6 mg/m (1.0g/mile) for 1981 and later.
There are pending regulations based on the Clean Air Act Amendments and on
establishment or revision of NSPS for stationary sources. Each major area is discussed
briefly.
The Clean Air Act Amendments require that the EPA Administrator promulgate
a short term NOX ambient air quality standard unless he finds that there is no signifi-
cant evidence that such a standard is needed to protect public health. The Act also
provides that the period of such a standard should be from 1 to 3 hours. A review of
acute short term N02 effects and the prevalence of critical levels of NO2 in the
atmosphere is underway and will be used as the basis of a decision for the revision of
the existing standard.
71
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THERMAL NOX
FUEL NOX
DILUENT ADDITION
STAGED COMBUSTION
is necessary to ensure that control technology does not adversely affect other
pollutants or system efficiency. A brief discussion of these factors is also given below.
The fixation of a small fraction of the molecular nitrogen in the combustion air
results in the formation of thermal NOX. Since the activation energies of several of the
formation reactions are high, the rate of formation of thermal NOX is strongly
temperature dependent. Thermal NOX is formed during the combustion of all fuels in
the regions of peak temperature that occur in all diffusion flames.
The oxidation of nitrogen compounds chemically bound in the fuel molecule
produces fuel NOX. Since significant amounts of nitrogen (0.1 to 2 percent by weight)
are found in all heavy fuels (residual oil and coal), fuel NOX is a major contributor to
the total NOX from these fuels. Based on small scale experiments, 50 to 90 percent of
the total NOX from residual oil and coal is fuel related, even though it is well
established that only a fraction of the fuel nitrogen is converted to NOX, with the
balance forming molecular nitrogen. The main factor affecting the conversion to NOX
is oxygen availability. The reactions appear to be relatively insensitive to temperature.
In general, a well designed boiler that is properly maintained and operated
produces low levels of carbonaceous pollutants (CO, HC, carbon particulate). Other
pollutant emissions (SOX and inorganic particulate) from these sources are less a
function of operation than of fuel composition and, in some cases, firing mode. On the
other hand, stationary engines can emit significant amounts of CO and hydrocarbon.
Since the combustion control techniques for NOX require changes in the way fuel is
burned, they also present the opportunity for optimizing the total combustion process
to achieve low levels of other pollutants.
Several control techniques can be applied to stationary combustion. Combustion
modification technology is the most cost effective and energy efficient for
conventional combustion sources. For any technique the degree of control depends not
only on the unit design but also on the fuel. Although NOX reductions in excess of 80
percent relative to uncontrolled levels have been achieved by combustion modification,
even greater control may be required. This may be obtained either by advanced
combustion or by supplemental techniques such as ammonia injection and flue gas
treatment. The various techniques are described briefly below.
The most effective control of thermal NOX is a reduction of the peak
temperatures in the flame zone. One approach is the addition of an inert diluent to the
fuel or air stream, thereby lowering the theoretical flame temperature at which
combustion takes place. The two most common approaches are flue gas recirculation
(i.e., the addition of relatively cool combustion gases recycled from the flue and mixed
with the combustion air) and water injection (i.e., addition of water or steam to either
the air or fuel stream). Of the two, water injection is the more effective on a mass
basis due to the latent heat of vaporization effect; however, it imposes a stack heat
loss that can be avoided with flue gas recirculation. These techniques are most effective
for thermal NOX and appear to have little effect on fuel NOX. For example, 70 to 90
percent maximum reductions have been observed for natural gas and distillate oil
in field and laboratory studies; for heavy oil, the range is 20 to 50 percent; and for
coal, 10 to 30 percent. Flue gas recirculation alone or in conjunction with other
techniques is used to achieve emission standards for gas and oil fired utility
boilers. Its potential drawbacks are increased mechanical complexity and capital costs.
Water injection is the state-of-the-art NOX control technique for gas turbine engines.
Staged combustion is based on operation with a rich primary combustion zone in
the furnace to reduce oxygen availability and peak temperature, followed by secondary
air injection to achieve carbon burnout. The reduced oxygen availability reduces the
conversion of fuel nitrogen to NO and the reduced peak temperature and subsequent
heat removal prior to secondary air addition reduces thermal NOX. One method of
implementing this control is illustrated in Figure 1. The air supplied to the burners
is less than the amount necessary to completely combust the fuel, which produces a
fuel-rich primary zone. Although the effectiveness of staged combustion increases
significantly as the primary stoichiometry is decreased toward 75 percent of theoretical
air, actual coal furnace primary zone stoichiometry is limited to 95 to 100 percent
72
-------
BURNER DESIGN
theoretical air by operational considerations (e.g., slagging, corrosion). The secondary
air is added above the top row of burners and an equal or greater secondary zone
residence time is provided for carbon burnout. Although up to 90 percent reduction of
NOX has been observed in coal fired laboratory systems, the maximum practical
reduction achieved on field operating boilers under actual or experimental conditions is
30 to 50 percent. Staged combustion is used in a number of configurations to achieve
the NSPS for coal fired steam generators and is also employed to meet standards for
oil and gas fired units.
Although diffusion flame burners of many designs have been used in fuel
combustion for years, only recently has the modification of design approaches to
achieve emission control received strong emphasis. The essential elements of a diffusion
SECONDARY
AIR
LEAN
SECONDARY
BURN OUT
ZONE
\ i
i-
<-.t
RICH
PRIMARY
ZONE
FIGURE •\-Stagedcombmtion
73
-------
ADVANCED CONCEPTS
NOX FLUE GAS
TREATMENT
FUTURE TRENDS
flame burner are a fuel introduction system and a burner throat to supply combustion
air. Design variables used to achieve stable combustion and good fuel conversion
efficiency include fuel distribution (controlled by injector design) and the rate of air
mixing (controlled by throat velocity, use of swirl, and/or design of the flame holder).
These same variables can control fuel and air mixing histories for emission control;
however, the flame characteristics required may be significantly different than the
conventional practice. The fuel and air mix initially in a primary reaction zone which
contains a wide range of stoichiometries, from very rich to very lean. This character-
istic of diffusion flames appears to result in the partial conversion of fuel nitrogen to
NOX. The balance of the combustion air is mixed with the primary zone products
farther downstream and combustion is completed. In addition, relatively cool combus-
tion products recirculate within the combustion chamber and are entrained by the
flame. This entrainment can provide a diluent effect which reduces peak temperature
and, therefore, reduces thermal NOX. Several pulverized coal burners designed to
reduce NOX have been tested by boiler manufacturers; reductions of 30 to 50 percent
relative to uncontrolled levels have been achieved. A modified burner design is cur-
rently used by one manufacturer to achieve the NSPS for coal fired utility boilers.
Entrained combustion gas recirculation burners have achieved NOX reductions in excess
of 50 percent for clean fuels (natural gas and distillate oil). In addition, several studies
of advanced burner designs for heavy oil and coal have shown the potential for 65 to
90 percent reduction relative to uncontrolled emissions.
Alternate combustion approaches do not employ classical diffusion flames and,
therefore, may allow very low levels of NOX. For example, catalytic combustion,
which is still being studied on the laboratory scale, has shown the potential for NOX
emissions below 10 ppm for clean fuels. Further development is required to assess the
full potential of this emerging technology in practical systems.
The ammonia injection technique involves the injection of ammonia (NH3) into
the boiler firebox above the combustion zone and the subsequent reduction of the
NOX to N2 by homogeneous reaction. The process requires careful NH3 to NO ratio
control and injection at the proper temperature. Reductions of 90 percent have been
achieved in the laboratory and 40 to 60 percent in field operating boilers. Due to
reagent requirements, it is anticipated that this technique will be used to supplement
combustion control techniques where very low NOX levels are required.
Many processes for NOX flue gas treatment have shown the potential for high
removal efficiency. Selective catalytic reduction processes using ammonia as the
reductant are the most developed and most promising flue gas treatment processes.
Although there are many variations, anhydrous ammonia is usually injected into the
flue gas after the boiler economizer, and the resultant mixture is passed over a catalyst.
The ammonia selectively reduces the NOX in the presence of the catalyst to molecular
IXI2 which then passes out of the NOX removal system and into the boiler air heater.
Selective catalytic reduction processes can remove 90 percent of the NOX from the
flue gas of a combustion source. In Japan, selective catalytic reduction processes
have been successfully installed on commercial-scale gas-and oil-fired sources and are
planned for coal-fired sources. A variation of the process can simultaneously remove 90
percent of the NOX and SC>2 in combustion flue gas. The process uses copper oxide to
absorb the SOX, and the resulting copper sulfate acts as a catalyst in the reduction
of NOX to N2 with ammonia. A multiple reactor system is required to allow for
continuous treatment of the flue gas and regeneration of the reactor saturated with
copper sulfate. In the regeneration cycle, hydrogen is used to reduce the copper
sulfate, and a concentrated S02 stream is produced which can be used to generate a
salable by-product.
The uncertainties of key variables make the quantitative prediction of future
trends very difficult; however, several factors appear to indicate the need for more
stringent NOX control capabilities in several areas. Some of these are discussed briefly.
The National Energy Plan calls for a significant increase in coal utilization by
industrial and utility sources. The actual increase depends on (a) coal production
capability, (b) energy consumption growth rate, (c) nuclear energy expansion rate, (d)
economics, and (e) environmental regulations. A first step is that virtually all new
74
-------
ALTERNATE FUELS
NO* CONTROL PROGRAM
LOW NOX COAL BURNER
utility boilers are coal fired. The result on NOX emissions from this source can be
generally illustrated by the fact that the current NSPS for coal-fired utility boilers are
2.3 and 3.5 times those for oil- and gas-fired boilers, respectively. With the 1971 NSPS
for coal-fired utility boilers, one recent projection indicates that the increase in total
NOX emissions from 1972 to 2000 would be from 30 to 80 percent dependent on the
assumptions of energy growth and nuclear capacity. Progressively higher levels of
emission controls through 1988 are required to significantly reduce the rate of
increase. Therefore, major emphasis on emission controls for coal-fired industrial and
utility boilers appears to be imperative.
Significant effort is underway in the United States to develop and commercialize
processes for producing alternative gaseous, liquid, or solid fuels from coal or shale.
Although most of these processes significantly reduce two of the objectionable
components (sulfur and mineral matter) associated with coal, they do not eliminate
chemically bound nitrogen. Typically, liquid fuels derived from coal and shale have
nitrogen contents from 0.5 to over 2.0 percent by weight. Although this nitrogen can
be at least partially removed by hydrotreating, it is potentially an expensive and energy
intensive process. Similarly, low and medium Btu fuel gas produced from coal has the
potential for containing up to 4000 ppm NH3 and cleanup, particularly at high
temperature, remains difficult. Evidence indicates that combustion modification should
be equally or more effective for alternative fuels than for coal and heavy petroleum
oil. Further development of the technology on the specific fuels is required.
Very low levels of NOX maV De required under several circumstances. First, the
short-term NO2 standard being considered may require stringent control in certain
areas. The degree of control and the specific sources requiring control for any given
location have not been established. It is also not obvious if large point sources or area
sources will be the prime target of control. Second, regulations requiring the
prevention of significant deterioration may require very low levels of NOX in certain
areas if development is to take place. Finally, certain local situations may require
increased NOX control capability. All of these factors provide impetus for establishing
the optimum control achievable by (a) conventional combustion, (b) advanced
combustion, and (c) post combustion treatment.
The EPA's Industrial Environmental Research Laboratory at Research Triangle
Park, N.C., is vigorously pursuing a program to develop and demonstrate NOX control
technology for a broad range of combustion sources burning a variety of fuels. Based
on both experience and projections, major program emphasis is on coal combustion in
industrial and utility boilers. Other source/fuel combinations are also covered, based on
similar considerations. The program's technical approach is based on a balanced and
coordinated mix of technology application, technology development, and fundamental
research. In general, technology being readied for evaluation in field applications has
been developed under EPA sponsorship. Optimization of the technology at the
development stage has resulted from an empirical experimental approach and a
complementary fundamental understanding of critical phenomena in the NOX
formation and destruction processes. The overall program has been discussed in detail
previously in Energy/Environment III (EPA-600/9-78-022). The purpose of this paper
is to summarize the significant technical progress over the past year. Specific program
areas are discussed in detail below.
Many, if not all, new utility and industrial boilers with a thermal input greater
than 35 MW will be fired with pulverized coal. Wall-fired, field-erected watertube
boilers constitute a dominant fraction of the capacity in these boiler classes. The low
NOX coal burner has the potential for direct application to new and existing boilers.
The program consists of three major elements: (a) burner design and scale-up criteria,
(b) extension of the applicability of the technology, and (c) field evaluation of its
performance on practical boilers.
Since the control of both thermal and fuel NOX from pulverized coal combustion
is strongly dependent on the temperature and stoichiometry in the primary zone, the
most direct approach is to redesign the burner to achieve the required fuel/air
distribution. In 1971 the EPA initiated a small scale study to identify the important
burner design parameters for NOX control. This study identified a distributed air
burner concept that had the potential for very low NOX emissions with both high
75
-------
carbon utilization efficiency and acceptable flame characteristics. This pilot scale work
was carried out at thermal heat inputs of 1.5 to 3.0 MW, which is a factor of 10 to 40
less than practical pulverized coal burners currently in use. Due to difficulties in scaling
burner thermal performance by even a factor of 2, current design practice is to make
incremental capacity changes, or simply install more burners of the same size. There-
fore, to obtain industry acceptance of the low NOX burner technology, it was neces-
sary to identify scaling criteria and to evaluate the burner performance at as close to
practical size as possible. A project was initiated to develop scaling criteria for low
emission burners. As an essential part of the program, a unique combustion facility
capable of firing coal and other fuels at a thermal input up to 40 MW was designed,
constructed, and used to study burner scale-up. The basis of the low NOX coal burner
is a distribution of the combustion air to control the reaction history of the coal. This
is shown conceptually in Figure 2. The coal is introduced with primary air and the
initial devolatilization reaction takes place at a very rich stoichiometric ratio (SR^)
which results in evolution of fuel nitrogen intermediates (XN) under conditions where
oxidation to fuel NOX is low. Secondary air is introduced in a way which provides a
gradual leaning out of the reaction zone to a stoichiometry (SR2> which is still fuel-
rich. This gradual mixing allows formation of NOX and a subsequent reduction by XN
to form N2- Both the temperature and stoichiometry history of this rich reaction zone
determine the level of NOX that can be achieved. Finally, tertiary air is mixed with the
reaction products to give a lean burnout zone (SRs). In this zone any residual XN
species are converted predominantly to NOX, any nitrogen remaining in the char is
ponverted predominantly to N2, and fuel species (char, CO, HC, H2> are oxidized to
give complete combustion. Complete reaction of the carbon in the char is espcially
important from the standpoint of both efficiency and emission performance.
FIGURE 2—Conceptual sketch of low NOX burner system
The design of one experimental burner used to achieve these conditions is shown
in Figure 3. The design incorporates a retractable oil gun for use on startup and a
divided secondary air channel to provide flexibility on turndown.
DESIGN FOR THREE
FIRING RATES
76
In an attempt to optimize the burner performance, several other burner con-
figurations have been evaluated. The initial evaluations of burner configurations are
carried out at 4 thermal MW and promising designs are scaled up for testing at 16 and
35 thermal MW. The results for one design operating at optimum conditions for all
three firing rates are shown in Figure 4 where NOX emissions are plotted versus the
combustion air supplied through the primary and secondary channels. In all cases the
-------
SWIRL VANES — ft
1
1 .
< /^
>C^/
COAL &_/^x^
PRIMARY
1
SECONDARY
AIR
J
yi
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V /I
Xl
— i
i /
K
K
TE
|
i-**'
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RTIARY
AIR
r
^
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- i
\
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*-
^
'•'•'•f'-'i
RETRACTABLE
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\\r\~7~f\ P
CERAMIC
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^ COMBUSTOR
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FIGURE 3-Sketch showing major features of 15-thermal-MW distributed mixing burner
400
E 300
a
a
o
cc .
a.
o
I-
<
X
O
200
100
COAL - UTAH
PRIMARY AIR - 25 percent THEORETICAL
OPTIMUM BURNER CONDITIONS
O4 THERMAL MW
Q 16 THERMAL MW
A35THERMA1 MW
0
30 40 50 60
PRIMARY PLUS SECONDARY AIR (THEORETICAL), percent
: FIGURE 4-Effect of burner scale on Nox emissions
70
77
-------
FUEL SCREENING
overall combustion air is 125 percent of the theoretical amount for complete com-
bustion. The 4 thermal MW burner produces higher emissions than either of the two
large burners. The 16 thermal MW burner produces emissions below 86 ng/J (approx-
imately equivalent to 175 ppm at zero percent (02) for all primary zone conditions),
while the 35 thermal MW burner achieves that level with 50 percent of theoretical air
through the burner. The three burners are geometrically scaled to provide an evaluation
of that approach to scale-up. Other burner design and/or scale-up approaches give
similar overall trends, but have a significant effect on the operating conditions to
achieve minimum emissions. The 16 and 35 thermal MW burners are in the size range
of the burners used on practical boilers which provides additional confidence in the
applicability of the technology.
Of all the fossil fuels currently used in the United States, coal is not only the
most abundant, but also presents the most complex problem of combustion and
emission control. In addition, there is no typical coal; properties of a given coal can
vary within the same seam. In spite of the wide ranges of composition that affect both
the way the fuel burns and the pollutant emissions, a general picture of the important
pollutant formation mechanisms can be presented by discussing phenomena that occur
in terms of a single coal particle. In fact, coal probably does not burn as single
particles and the following discussion is phenomenological. For combustion in practical
systems, pulverized coal is mixed with a fraction of the combustion
air (called primary air) and introduced into the furnace through the fuel injector of the
burner. The amount of primary air is determined by both the fuel properties and
burner design; however, it is normally 10 to 30 percent of the theoretical air required
for complete combustion. The actual stoichiometry under which any fuel particle
reacts will depend on the fuel and air mixing history. The sequence of events occurring
for a single coal particle is shown in Figure 5, which indicates two combustion modes
(volatile evolution and char burnout) as discussed below. Although every coal particle
undergoes similar types of processes, the environment under which pollutant formation
reactions occur is governed by the aggregate coal particle cloud reaction history.
VOLATILE PORTION
As the coal particle is heated by radiation and convection, the volatile portion of
the coal substance begins to evolve. The initial products contain carbon and hydrogen
and probably represent side chains and cross linkages between the ring structures in the
coal molecule. These initial volatiles react with the surrounding air and partially de-
plete the available oxygen. As the temperature increases and the ring structures begin
to fragment, nitrogen-containing intermediates (designated XN) are evolved and begin
to react with oxygen to form NOX. Subsequent reactions of XN with NOX and other
species produce molecular l^. The amount of nitrogen evolved in the volatile fraction
depends on the ultimate particle temperature; the fate of the XN compounds depends
on the local stoichiometry around the particle. For fuel lean conditions, a substantial
fraction will be converted to NO. For fuel rich environments, the production of
molecular nitrogen increases until an optimum stoichiometry is reached; then, for even
richer stoichmetries, the residual nitrogen species (XN) are retained unreacted and burn
in leaner secondary combustion zones. It also appears that some of the NOX formed
can be reduced to N2 by heterogeneous reaction with coal particles or char.
DEVOLATILIZATION
During this devolatilization process, inorganic and organic sulfur species are
released as sulfur intermediates (designated XS). In general, the XS species are
essentially quantitatively converted to sulfur oxides (SO2 or S03> at some point during
the combustion process; however, these species may undergo different reactions or
may influence other reactions in this devolatilization zone. Two examples may be
cited. First, a significant amount of the sulfur in some western coals can be retained in
the ash, probably as a sulfate; however, this retention may be enhanced if the sulfur
could be captured during devolatilization. Second, sulfur species can influence the
conversion of nitrogen species (XN) to NO and other products; therefore, the history
of sulfur intermediates relative to nitrogen intermediates (XN) is important in the
devolatilization zone. Finally, a portion of the mineral matter from the coal is
vaporized in the devolatilization zone and subsequently condenses and/or coalesces to
form submicron particulate. The temperature and stoichiometry during devolatilization
probably influences the potential for fine particulate formation.
78
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CHAR COMBUSTION
Following devolatilization, the residual coal matter (called char) is burned out.
The composition of the char depends strongly on the conditions in the devolatilization
zone; however, its major components are generally carbon and mineral matter with
variable amounts of nitrogen and sulfur species. By the nature of coal combustion,
char combustion occurs under predominantly fuel lean conditions. By design, carbon
burnout is nearly complete, thereby maximizing energy efficiency and minimizing the
carbonaceous particulate. The residual nitrogen species in the char form NO and N2
during burnout in a mode of combustion which appears to promote N2 formation. The
sulfur species are either oxidized to SC>2 or retained with the mineral matter. The
residual mineral matter forms particulate (flyash) in the 0.1 to 50 /urn size range.
Simultaneous with char burnout, residual gaseous species (CO, \\i, HC) must also be
burned out. This mechanistic understanding of pollutant formation processes forms the
basis for optimization of combustion techniques for emission control which are based
on tailoring the air and fuel mixing history to minimize all objectionable species.
FUEL SCREENING
EXPERIMENT
The effect of coal type on NOX emissions has not been previously studied in a
systematic manner under completely comparable conditions. In view of the potential
for the nitrogen evolution and the fuel-air mixing histories for different coals, a fuel
screening experiment was required to assess the applicability of the low NOX burner
technology to the range of U.S. coals. Initial screening is carried out at small scale,
followed by more limited testing in large burners. The small scale experiments are
PORES;CRACKS
OR FISSUHES
INCLUSIONS OF
MINERAL MATTER
HETEROGENEOUS
NO REDUCTION
MINERAL MATTER
VAPORIZATION
CHAR BURNOUT NITROGEN
HOMOGENEOUS NUCLEATION
AND COLLISION COALESCENCE
o o o
° o° o
SUBMICRON ASH
<0.1 pm
HETEROGENEOUS
CONDENSATION
FLY ASH
0.1 -50,jm
FIGURE 5--Pollutant formation during pulverized coal combustion
79
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carried out in a downfired refractory furnace shown in Figure 6. The burner shown is
an axial diffusion flame burner; however, other burner types are also used to assess the
effect of primary air-fuel mixing on emissions. The oxidant can be either air or an
artificial argon-oxygen mixture, which eliminates thermal NOX. The system is being
used to screen a large number of U.S. coals under both unstaged and staged conditions.
COAL PLUS
TRANSPORT AIR
AXIAL
AIR
c
c
c
c
c
c
F
r
c
f C
C
c
c
c
o
o
o
o
o
o
o
o
o
=1
ID
ZJ
Z)
3
Zl
ZI
13 _
=] 1
ZJ
ZJ
\
HIGH TEMPERATURE
REFRACTORY
INSULATING
REFRACTORY
FLUE
AUXILIARY PROPANE BURNERS
FIGURE 6-Small experimental facility
80
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NITROGEN RANGE FOR
U.S. COAL
The fuel NOX levels versus fuel nitrogen content for representative coal types are
shown in Figure 7 for the premixed fuel lean combustion mode. The data show the
wide range of nitrogen content for U.S. coals from 0.83 percent for an anthracite to
nearly 1.9 percent for medium volatile bituminous. The NOX values shown are
moderately to significantly higher than those measured for similar type coals in
practical boilers. This is believed to be caused by the premixed system giving higher
conversion of nitrogen compounds than occurs in diffusion flame burners. While the
NOX levels show a general trend to increase with increased fuel nitrogen, this is not the
only variable as illustrated by comparing coals of similar type and/or nitrogen content.
For instance, for the two lignites at about 1.2 percent nitrogen, the lower point is only
60 percent of the upper value. Similarly for the four high volatile bituminous coals at
1.4 to 1.6 percent nitrogen, the emissions range from 800 to over 1200 ppm with the
lowest nitrogen content coal giving the highest number. Note that the highest number
is produced by a Utah coal (1.4 percent nitrogen) which has been used for the bulk of
the burner scale-up work. These data appear to indicate that the manner in which the
nitrogen is bound in the coal affects the fractional conversion to NOX at a constant
operating condition. Although it has been postulated that the fraction of the nitrogen
evolved with the volatile matter is the important variable, a technique for character-
izing the differences has not yet been found.
1300
- 1200
r^
° 1100
1 1000
EC
UJ
°- 900
CD
§ BOO
B-
| m
& 500
1 400
S 300
LEGEND
• BITUMINOUS - HIGH VOLATILE
• BITUMINOUS - MEDIUM VOLATILE
* SUB-BITUMINOUS
* LIGNITE
* ANTHRACITE
PREMIXED
5 PERCENT 02 IN STACK
I
I
|
I
I
|
|
0.8
FIGURE
0.9
1.0 1.1 1.2 1.3 1.4 1.5 1.5
COAL NITROGEN CONTENT, PERCENT DRY-ASH FREE
7-Effect of coal nitrogen on fuel NOX
1.7
1.8
1.9
STAGED COMBUSTION
The primary interest is in the effect of fuel on the NOX levels achievable under
staged combustion conditions related to the low NOX burner. The NOX emissions as a
function of nitrogen content are shown in Figure 8 for a fuel-rich premixed primary at
the optimum stoichiometry. The overall stoichiometry is brought to 125 percent of
theoretical air by the addition of secondary air at a fixed axial location. Under staged
conditions the differences between coals are much smaller and NOX emissions are
between 300 and 400 ppm almost independent of the fuel nitrogen content. Both the
two lignite (around 1.2 percent nitrogen) and the two bituminous coals (1.4 to 1.6
percent nitrogen) have retained their relative position although the absolute difference
is less than 100 ppm. The absolute levels are also greater than those observed with the
low NOX burner (Figure 4). There are a number of factors that may account for
this including: (a) effects of scale, (b) the premixed primary provides a less rich
primary for the same burner stoichiometry due to mixing effects in the large
burner, (c) the premixed primary stage does not have the distribution of
stoichiometries which may lead to lower levels in the burner, and (d) the higher
temperatures in the refractory lined system may affect both fuel devolatilization
history and thermal IMOX formation. Limited tests show that a three-stage system
with a very rich first stage (40 percent theoretical air), a less rich second stage
(60 to 90 percent theoretical air) and a lean third stage (125 percent theoretical
air) gives lower emissions than the two-stage system. It has also been shown that
interstage cooling can decrease NOX levels even further.
81
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FIELD EVALUATION
MAJOR PROJECT TASKS
600
o' 500
|
GC
S 400
300
200
= 100
STAGED PREMIXED
125 PERCENT THEORETICAL AIR OVERALL
OPTIMUM PRIMARY STOICHIOMETRY
LEGEND
LIGNITE
BITUMINOUS - HIGH VOLATILE
BITUMINOUS - MEDIUM VOLATILE
SUB-BITUMINOUS
0.9
1.0
1.8
1.9
1.1 1.2 1.3 1.4 1.5 1.6 1.7
NITROGEN CONTENT, PERCENT DRY MINERAL-MATTER FREE
FIGURE 8-Achievable NOX emissions in the small experimental facility
Overall, the fuel screening studies have been very valuable in identifying fuels
with different emission potentials. From these results a smaller number of fuels are
being selected for testing in the larger scale burners (3 to 35 thermal MW). If similar
trends are shown to exist, the screening procedure will be established as a viable
technique for low cost testing of specific fuels.
Although the performance of the experimental burner is encouraging, to be of
practical value, the burner must be evaluated on actual boilers operating over normal
duty cycles. The evaluation must include not only emissions measurements but also
system operability and thermal performance. Projects for this evaluation have been
started for both industrial and utility boilers. The scope of both projects is virtually
identical and the major difference is in boiler size and duty cycle. Industrial boilers are
defined as ranging from 35 to 175 thermal MW (nominally equivalent to 100,000 to
500,000 Ib of steam per hour); utility boilers are defined as going up to 300 electrical
MW. The major tasks are as follows:
• The Program Definition Task provides for host boiler selection engineering design
of a commercial prototype low NOX burner, definition of the required
measurement plan, and an overall program plan.
• The Burner Prototype Construction and Testing Task provides for construction
of one prototype of the burner and testing in the large watertube simulator used
in the burner development work. This testing will allow comparison of
experimental burner results, optimization of conditions over the expected
operating range, and resolution of mechanical problems. In addition, an example
of the commercial burner from each host boiler will be tested in the large water-
tube simulator to provide a direct performance comparison.
• The Boiler Baseline Characterization Task provides for an analysis of the emission
and thermal performance of each host boiler prior to modification as a basis of
comparison. This includes operation over a wide range of conditions and with
operating modifications to establish the minimum NOX achievable.
• The Burner Installation Task provides for fabrication of the required number of
burners, (see second task, above) and installation on each boiler. It also includes
instrumentation for performance evaluation, corrosion panels at appropriate
locations, and a TV camera for remote observation of the flame zone. Following
installation, the boiler is to be operated over a range of conditions and an
optimum operating point is to be established.
• The Long-Term Performance Evaluation Task provides for an 18-month test
period over the normal boiler duty cycle. Gaseous species and selected thermal
82
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CORROSION TESTING
STOKER BOILERS
performance measurements will be made continuously, with three to five 30-day
detailed evaluation periods equally spaced over the period.
• The Industry Coordination Task provides for a periodic review of the project
status by interested parties, including manufacturers and users. This activity will
be coordinated with the Technical Review Panel in the ongoing burner
development activity.
• The Boiler Restoration Task provides for removal of the low NOX burners and
restoration of the host boiler to the initial configuration.
• The Data Analysis Task provides for an analysis of the data from the pilot scale
study and a continual evaluation of performance during the field boiler
operation. The goal is to generalize the results and allow a projection of burner
performance in other systems with different fuels.
• The Design Approach Documentation Task will combine a factual summary of
the experience on each boiler with the data analysis from the Data Analysis
Task, above, to provide a general guide for application of the low NOX burner to
a wide range of boilers and fuels.
The industrial boiler project is being conducted by Energy and Environmental
Research Corporation (EER) with Foster Wheeler Energy Corporation as a major
subcontractor. The utility project is being performed by Babcock and Wilcox with a
subcontract to EER. Both projects are scheduled for completion in late 1982.
Current new boilers over 73 thermal MW input, which are designed to meet the
NSPS, incorporate staged combustion and/or improved burners in conjunction with the
normal firing design. There has been mixed evidence for the existence or extent of
accelerated waterwall corrosion with the fuel-rich conditions that may be produced in
the lower part of the firebox. Therefore, a project has been initiated to fully evaluate
these effects on four boilers of different firing configurations operating at or below the
NSPS of 300 ng NOX/J (0.7 Ib NOX/106 Btu). The evaluation of corrosion rates will
include the use of both removable corrosion panels and ultrasonic tube thickness
measurements before and after a 24-month operating period. Evaluation of emissions
will include both continuous gaseous pollutant measurements and Level 1 analysis for
potentially hazardous pollutants. This project will provide both a quantitative defini-
tion of any problem and identification of needed control approaches.
Three host units have been selected, one each manufactured by Combustion
Engineering (CE) [410 electrical MW], Babcock and Wilcox (B&W) [450 MW], and
Foster Wheeler [626 MW] . The fourth unit will be selected at a later date based on
test results. Baseline emissions have been measured on two units (CE and B&W) and
NOX levels are at or below the pending revised NSPS. The corrosion panels will be
installed on all three units during scheduled outages over the next year. If possible,
part of the corrosion panels will be removed for analysis during another scheduled
outage after one year and replaced with new panels which will subsequently be
removed and analyzed.
The stoker boiler firing system can be used for commercial and industrial boilers
in the range of 4 to 120 thermal MW; however, above approximately 40 MW,
pulverized coal may be cost competitive. With the emphasis on increased use of coal
for industrial steam generation, NOX control for stoker-fired systems must be
considered. The program covers field testing, a combustion modification program, and
laboratory work. Each of these program areas is discussed below.
Under joint sponsorship of DOE and EPA, the American Boiler Manufacturers
Association and KVB, Inc. are performing emission field testing on 10 stoker coal-fired
boilers over a range of steam capacities and designs. Reports on the first two systems
have been issued.
A contract is in negotiation to modify the firing system on five field operating
boilers to provide for NOX control. Two of the systems will be spreader stokers which
83
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is the firing mode used in larger size boilers, while three will be of the mass feed type
used in smaller boilers. Based on available information, the contractor will design the
applicable control techniques and install the equipment on the boilers. Each boiler will
be operated over a range of conditions to determine the optimum NOX control
achievable. Each boiler will be operated for a minimum of 30 days at its optimum
condition and comprehensive emission testing will be performed.
LABORATORY WORK
TANGEIMTIALLY FIRED
BOILERS
FLAME STUDIES
While the work on practical boilers can provide valuable guidance for NOX
control by modification of current stoker designs, a better understanding of the
pollutant formation processes is required to establish the approaches for the maximum
achievable control for new designs. While the reaction of coal in the overthrow region
of a spreader stoker appears to have some similarity to pulverized coal firing, the
pollutant formation processes are not well understood due to both the larger coal size
and the use of mass burning on a grate to complete the combustion. In the overthrow
region the coal is devolatilized and partially reacted in the hot gases rising from the
grate. The larger coal particles then fall on to the grate and burn in the mass mode
with combustion air supplied from underneath. The smaller particles may be carried
out of the combustion zone by the hot gases without ever reaching the grate.
A grant has recently been awarded to provide the required understanding of
these combustion processes. The approach is to examine each region of the stoker
separately, then to integrate the knowledge into a prototype system for testing. The
overthrow region will be simulated with a small tower furnace where coal with particle
sizes typical of spreader stokers will be reacted in either co- or counter-flowing streams
of hot gases. The temperature composition and stoichiometry of the gases will be
varied to determine the effects on both sulfur and nitrogen specie evolution from the
coal. Both the effluent gas and residual solids will be analyzed. The mass burning will
be simulated with a fixed bed experiment where beds of various thickness will be
burned under a variety of conditions. Based on the results of these experiments, a
model stoker will be constructed to evaluate the combination of the two combustion
modes in the optimum manner for a new stoker design.
For boilers without NOX control, tangentially fired boilers generally produce
lower NOX emissions than other firing methods; however, pilot scale data on the
lowest achievable NOX levels for tangential boilers are not available. In view of the
pilot scale performance of the low NOX burner for wall-fired boilers, a study has been
initiated to generate that data. A pilot scale furnace will be used to study tangential
firing at 0.5 to 1.0 thermal MW. Examination of the design approach and pictures of
the fireball of a tangential unit suggests that at least two phenomena need to be
studied.
First, the characteristic flame originating from each fuel injection elevation
strongly resembles the axial diffusion flames studied by Heap, i.e., an axial fuel jet
completely surrounded by a flame sheet. This configuration was shown to produce
lower NOX levels than more highly mixed swirl burners. It could be postulated that
this factor accounts for the differences observed in practical boilers; however, a second
possibility must also be considered. It can be argued from available photographs of a
tangential fireball that, within a short distance, the flame from each corner begins to
interact with other flames. It is well known that NOX can be partially reduced on
passage through a flame front. It has also been shown that NO added to the
combustion air of a lean residual oil flame could be reduced by up to 35 percent. If
the NOX formed in one flame of a tangential unit is processed by another flame front,
a similar reduction of NOX might occur. It is obvious these two possibilities are not
independent phenomena. The research program is structured to examine the effects of
both initial fuel/air mixing and flame interactions independent of the entire fireball.
The results will then be used to define experiments for the tangential configuration of
the pilot scale furnace.
Although the individual flame in a tangential boiler may be compared with an
axial diffusion flame from a circular symmetric swirl burner, there are some potentially
important differences. The axial diffusion flame studied by Heap and others has the
central fuel jet completely surrounded by combustion air; whereas, in the tangential
burner the bulk of the combustion air is added asymmetrically from ducts above and
84
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FLAME INTERACTION
below the fuel jet. In addition, the axial diffusion flame is surrounded by, and
entrains, relatively cool recirculated combustion gases; whereas, the tangential flame
has relatively cool combustion gases on the waterwall side, relatively hot combustion
gases from the center of the fireball, and very hot gases from the flames above and/or
below. Therefore, while the initial experiments on burner design tor air/fuel contacting
control can be carried out under symmetrical conditions, considerations must be given
to a series of experiments more closely simulating the asymmetric environment
described above. These single flame experiments will be based on available information
on axial diffusion flames and will be used to establish optimum configurations for
control of NOX formation in the early flame zone.
A second series of experiments will be performed to examine the effect of flame
interactions on emissions from various burner configurations. It may be postulated
that the two important variables in flame interactions are the axial distance at which
impingement occurs and the angle of impingement. The axial distance may be thought
of as representing the extent of reaction of the coal jet. Close to the injector the bulk
of the coal will be unreacted and the oxygen availability will be high. As the distance
from the injector increases the fraction of the coal reacted will increase up to a point
where all the volatile matter is evolved and the oxygen availability will decrease. The
point of interaction of this flame with the combustion products of a second flame can
be expected to have an influence on the NOX reduction that will result. While it
is not possible to predict the optimum point for a reduction of NOX by the flame
processing mechanism, it can be postulated that this point will occur before all of the
volatiles are consumed and, therefore, where fuel intermediates (H2, CO, NH3, etc.)
are available to reduce the NOX. This point will also depend strongly on the character
of the flame and may be more likely to occur if the flame is fuel rich overall. While
the axis of the two adjacent fuel injectors on the same elevation is at 90°, the effect
of the fireball appears to deflect the later portion of each flame from the injection
axis, thereby decreasing the angle at which the adjacent flames interact. A change in
this angle can be expected to influence the degree of interaction by affecting both the
distance and the mixing processes of the two jets. None of the data currently available
provide a basis for predicting these effects.
To examine the two phenomena discussed above, an experiment with two
interacting flames will be conducted. Figure 9 shows a schematic of the experimental
INTERSECTION ANGLE a
INTERSECTION DISTANCE X
FIGURE 9-^Sketch of flame interaction experiment concept
85
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HEAVY LIQUID FUELS
FUEL-SCREENING
EXPERIMENT
variables to be considered. A modification of the single burner extension of the
furnace will provide for an evaluation of the effects of distance and angle for selected
burner configurations.
The results of these two well-characterized experiments will be used to design
concepts for testing in the tangential model of the EPA furnace.
The experience in pilot scale development of staged combustion and advanced
burner design indicates that it is more difficult to achieve high percentage reduction of
NOX for heavy liquid fuels than for coal. Some evidence exists to indicate that the
difficulties may arise from differences in the way that the nitrogen is bound in the fuel
and, therefore, the reaction history of the fuel nitrogen intermediates. More refractory
nitrogen in the petroleum derived residual fuel oils may be released later in the
combustion processes when more oxygen is available for conversion to NOX. The
synthetic liquids derived from coal and shale not only have larger amounts of nitrogen
but also have the nitrogen distributed over the full boiling range of the crude. In
addition, major limits on NOX control for petroleum residual fuel oils is the onset of
carbonaceous paniculate (smoke) formation as the primary zone becomes fuel rich.
Since the formation of carbonaceous particulate is related to the carbon-hydrogen
ratio of the fuel, this limitation may become more severe for synthetic liquids derived
from coal.
A fuel screening experiment is in progress in an attempt to quantify the effects
of fuel composition on both NOX and carbon particulate emissions. A small furnace
similar to the one shown in Figure 6 is used. The fuel is introduced through a sonic
atomizer which produces a relatively narrow cut of small droplets (20 /urn). The
droplets are well dispersed in the combustion air stream, producing a mixture believed
to be similar to the premixed coal burner discussed earlier. This system allows a rapid,
LLJ
U
DC
Q
0.4 0.8 1.2 1.6
NITROGEN CONTENT, PERCENT WEIGHT
FIGURE 10—NO., emissions from liquid fuels
86
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cost-effective screening of a wide range of fuels even when the availability is limited
to small quantities, such as for many synthetics. The system can be run both staged
and unstaged for an assessment of the emission formation and control potential.
IMOX EMISSIONS/NITROGEN
CORRELATED
The correlation of NOX emissions with fuel nitrogen content is shown in Figure
10 for fuel lean conditions. The lower curve shows the fuel nitrogen conversion as
determined by substituting an argon oxygen mixture for the combustion air. The fuel
data for petroleum-, shale-, and coal-derived liquids show the same trend, that is, NOX
increasing with fuel nitrogen content and the fractional conversion decreasing with
increasing nitrogen. This is similar to previous data for doped distillate oil and for
limited petroleum residual testing. Considering the differences in the fuel sources and
properties, it is remarkable that the trend is so consistent. It is also in marked contrast
to the previously shown behavior for coals (Figure 7). The upper curve representing
total NOX, using air as the oxidizer, is drawn through the petroleum-derived fuel data
up to 0.8 percent nitrogen and through synthetic fuel data at higher nitrogens. The
difference between the two curves represents the thermal NOX. The thermal NOX for
pure alternate fuel appears to be consistently higher than that for petroleum oils.
(Some of the data shown for the synthetics are blends with petroleum residuals and
these approach the petroleum line as the percentage synthetic decreases.) The reasons
for this apparent difference have not been determined.
a
a.
H
Z
ai
O
cc
LU
a.
2000
1800
1600
1400
1200
1000
X
800
600
400
200
PERCENT EXCESS
OSTAGING PORT NO. 4
D STAGING PORT NO. 4
ASTAGING PORT NO. 8
OSTAGING PORT NO. 8
SHALE OIL/SONICORE NOZZLE
50 60 70 80 90 100 110
PRIMARY AIR (THEORETICAL), percent
FIGURE 11 —Effect of primary air on NOX emissions for a crude Parahoe shale oil
120
87
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STAGED CONDITIONS
GAS TURBINE ENGINES
BENCH SCALE
COMBUSTOR
These screening data have been used to select a limited number of fuels for
testing under staged conditions. An example of the results obtained for a crude shale
oil is shown in Figure 11 for two primary zone residence times. The primary air is
introduced through the burner and secondary air to complete the combustion is
introduced through ports at different downstream locations. In both cases emissions
are reduced from about 1900 ppm to less than 200 ppm. The longer residence time
gives a somewhat lower minimum over a broader range of primary rates, a
characteristic shown in most staged combustion experiments. The minimum achievable
NOX emissions for a wide range of fuels are shown in Figure 12. The emissions for
petroleum-derived fuels show a sharp rise as nitrogen content increases from zero to
0.6 percent, then the emissions for the synthetics exhibit nearly no increase as nitrogen
content increases from 1.0 to 2.0 percent. The reason for the differences in staging
effectiveness is believed to be related to the volatility of the fuel nitrogen as will be
discussed later.
The closed symbols on Figure 12 show the emissions trend for fuels tested in a 1
MW thermal package boiler simulator using a similar sonic nozzle and axial air flow
distribution to simulate the tunnel furnace. The emissions follow the same trend as the
tunnel furnace; however, in general the NOX levels are somewhat higher. The carbon
particulate formation tendency of fuels under staged conditions has also been briefly
studied in this system. At minimum NOX, the smoke number for the crude shale was
significantly lower than that for the petroleum oil tested. Sufficient quantities of
coal-derived oils are not yet available for testing. These results show that the fuel
screening technique is quite useful for indicating the performance of fuels in practical
combustors.
The development of a low emission combustor technology for stationary gas
turbine engines (SGTE) is nearing completion. The goals of this program were to
identify and experimentally demonstrate (in full-size hardware) a new combustor
concept capable of producing NOX emissions less than 50 ppm on clean fuels and less
than 100 ppm on fuels containing up to 0.5 percent chemically bound nitrogen
without the use of water injection. These emission goals were to be achieved while
maintaining very low CO and unburned hydrocarbon performance. The exclusion of
water injection as a considered control approach derived from the efficiency penalty
and operational problems associated with that technique while consideration of fuels
containing bound nitrogen resulted from EPA's belief that SGTE's would need to burn
dirtier fuels such as residual oil or synfuels if they were to attain a sizeable portion
of the utility market.
The program was structured with a phased approach to include (a) identification
of candidate design concepts, (b) bench scale experimental evaluation of the concepts,
(c) selection of the most promising design approach, scaleup of the concept to the
25 MW size range and construction of full scale hardware, and (d) rig testing of the
full scale hardware. In all, 29 concepts were evaluated on the bench scale. While a
number of the concepts were capable of meeting the program goal on clean fuels, the
only combustor concept capable of meeting the goals on both clean and nitrogen
containing fuels was a configuration called the rich burn/quick quench concept shown
in Figure 13. This configuration involves a premixed fuel and air stream issuing into a
fuel rich primary zone. The combustor is then contracted at the point of secondary air
addition to increase the rate of mixing between primary and secondary streams and to
provide a quick transition from fuel rich to fuel lean stoichiometry, thereby mini-
mizing thermal NOX. Tertiary air ports are also provided to bring the exhaust to the
overall fuel/air ratio for the required turbine inlet temperature.
The performance of the bench scale combustor is shown in Figure 14. The
shaded zone shows the range of primary zone combustor residence time typical of
current generation stationary gas turbine engines. For both clean and nitrogen
containing fuels (simulated with a pyridine doped distillate oil) the combustor
exceeded the performance goals. CO emissions were well below the 100 ppm goal. For
clean fuels the low NOX and CO levels were readily achieved over the entire engine
operating cycle. For dirty fuels it was necessary to maintain control over primary zone
stoichiometry (01=1.2 to 1.5 or 82 to 67 percent of theoretical air) in order to achieve
low emissions over the operating cycle. The problems associated with maintaining
stoichiometry control (i.e., variable geometry) are significantly mitigated by the facts
88
-------
^ 300
200
100
11B# THEORETICAL AIR OVERALL
OPTIMUM PRIMARY STOICHIOMETRY
O
y
LEGEND
• PETROLEUM DERIVED
A SHALE DERIVED
• COAL DERIVED
CLOSED SYMBOLS - TEST TUNNEL
OPEN SYMBOLS - BOILER SIMULATOR
i i i i
0.2 0.4 0.8 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
NITROGEN CONTENT, PERCENT WEIGHT
FIGURE 12-Minimum achievable NO,, for liquid fuels under staged combustion conditions
TERTIARY DILUTION HOLES
PREMIX TUBE
PRIMARY ZONE
QUICK QUENCH SLOTS
FIGURE 13—Low NOX gas turbine combustor
100
T
RANGE FOR CURRENT
GENERATION GAS
TURBINE COMBUSTORS
600°F, 50 PSIA
4% PRESSURE DROP
FUEL
• NO. 2 WITH 0.5% N
V NEAT NO. 2
I
I
0 0.04 0.08 0.12 0.16 0.20 0.24 0.28 0.32
PRIMARY ZONE RESIDENCE TIME , SEC (COLD)
FIGURE 14—Gas turbine combustor performance
89
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SCALED UP COMBUSTOR
STATIONARY
RECIPROCATING ENGINES
that control is only required for the primary zone, and only 10 to 20 percent of
the total engine flow passes through the primary. A simple variable damper on the
inlet to the premix tube has been shown to provide the required control at a reason-
able pressure drop. At longer residence times, NOX emissions were 20 ppm for clean
fuels and 40 ppm for a 0.5 percent nitrogen doped fuel. In both cases these NOX
emissions are a factor of 2.5 less than the program goals. These results have implica-
tions for the potential of the combustor for new design stationary gas turbine engines
where combustor residence time may not be a major constraint.
This combustor concept was scaled up to a size commensurate with a single can
from a multiple can 25 MW machine. Full scale rig testing of the hardware was
performed and the results indicate a successful scaleup procedure. NOX emissions less
than 45 ppm were recorded for clean fuels while on dirty fuels the NOX levels were
around 75 ppm. These results are consistent with those for the bench scale combustor
at the residence time used in the scaled up combustor (4 msec). Nitrogen containing
fuels tested at full scale include a distillate cut shale oil containing 0.25 percent
nitrogen and number 2 oil doped to 0.5 percent nitrogen as pyridine. Future plans
call for examining the combustor on an SRC II fuel, a residual shale oil, and a
petroleum-derived residual oil.
Stationary reciprocating engines are used both as compressor drives and for
generation of electric power. The stationary engines are large bore, two- and four-cycle
devices operating at relatively low speed as compared with automotive engines.
Dependent on the fuel, the engines may be either diesel or spark ignition. While the
NOX control techniques developed for stationary continuous combustion systems are
applicable in principle, the intermittent high pressure combustion processes in
reciprocating engines present difficulties in application.
The goal of the reciprocating engine program is to achieve a 50 to 60 percent
reduction in NOX without increase in carbonaceous emissions and with a minimum
impact on fuel efficiency. The initial concept screening has been completed and a
prioritized list has been prepared for diesel and spark ignition categories. These
concepts will be screened on laboratory engines and the most promising technique for
each category will be tested on a full scale engine for a short period. Longer field test
periods are planned for a subsequent program.
INTEGRATED RESIDENTIAL
OIL FURNACE
WARM AIR DESIGN
The degree of control achievable with current oil- and gas-fired residential
furnaces is limited by the relative lack of flexibility of operating conditions and by
cost constraints. This class of equipment emits pollutants near ground level in
populated areas during a limited period of the year (i.e., the heating season). In
addition, it consumes a significant amount of energy, almost exclusively as clean
fuels (e.g., gas and light oil). An integrated residential furnace has been developed
which has the potential for significant NOX control and for increased efficiency. The
main features of the furnace are shown in Figure 15. The initial development was the
burner head for retrofit to existing furnaces which achieved a 15 to 30 percent NOX
reduction. It was also shown that matching the burner head with a new firebox could
produce much larger NOX reductions (e.g., 75 percent). As a result quantitative
matching criteria were developed including (a) 25 percent heat removal from the
firebox to minimize NOX emissions, (b) chamber dimensions for minimum
carbonaceous emissions and excess air requirements, (c) provision of the thermal
mass to achieve a minimum firebox temperature of 333K for clean ignition, and (d)
tunnel firing preferable to side firing.
The best system to achieve the criteria standards is a hydronic furnace; however,
the bulk of the population are side fired warm air furnaces. Therefore, a warm air
design embodying the criteria was developed using a finned metal firebox, as shown in
Figure 15. The combination also allowed firing at a low excess air (20 percent) and
minimum stack temperature for maximum efficiency during the operating cycle. In
addition, two other features were designed into the furnace to maximize overall system
efficiency. The burner draft damper prevents flow of air through the firebox when the
burner is not firing, thereby reducing the off-cycle heat losses to the flue. The
sealed air system provides outside air for both combustion and barometric draft
90
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Sf ALtU COMBUSI ION AIM SYSTEM
STANDBY DRAFT C.ONlRlH
COMBUSTION AIR FILTER
QUIET PULSE FREE STATOH
OPTIMUM BUHNER HEAD
AIR COOLED FINNED FIREBOX
FIGURE 15—low emission integrated furnace components
HOST RESIDENTIAL
FURNACES
control. This eliminates the use of conditioned air for these purposes and, thereby,
should reduce infiltration of air into the house. The prototype was tested in the
laboratory and produced a 65 percent reduction in NOX relative to the existing furnace
population with no increase in carbonaceous emissions. It was estimated that the
furnace concept should result in about a 10 percent increase in thermal efficiency
relative to the unmodified furnace.
Six furnaces were constructed and installed in host residences, three in Albany,
N. Y., and three in Boston, Mass. The furnaces have been operated under normal duty
cycles for two heating seasons (1977-79) and have performed satisfactorily. The
emission performance has been equal to or better than the laboratory prototype for
most of the period; however, in the mid-winter some lower quality oil containing
sludge and greater amounts of fuel nitrogen resulted in some off-specification
emissions. During the evaluation period, the efficiency of the furnaces was measured
in several ways. The most rigorous measurement was cycle average efficiency which
was based on total fuel input and warm air output over a total of three months for
each furnace. This method, which measures useful heat delivered to the host residence,
averaged nearly 75 percent over the first heating season. A strong correlation of
efficiency for any given cycle and the fraction of the cycle time the burner was firing
was developed. In addition, the fuel use for the test period was compared to the prior
fuel deliveries to the residence. Since the thermostat was not controlled during either
period and the fuel history was somewhat difficult to reconstruct accurately, the
comparison should not be taken literally. Fuel savings of over 20 percent were
observed for several furnaces and are believed to be essentially accurate. Overall the
91
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ADVANCED CONCEPTS
integrated residential furnace has shown the potential for significant emission
reductions coupled with increased efficiency.
The programs discussed above involve modifications to conventional combustion
equipment to achieve NOX reductions. There are some indications that the very nature
of diffusion flame combustors may place some lower limit on the achievable NOX
emissions. Since there may be situations where even lower emissions are required, a
number of advanced concepts are being examined. Many of these are combustion
processes based on modifications of conventional combustors or on novel design. In
addition, there are add-on treatment processes being pursued to achieve high removal
efficiencies as supplements to combustion modification. Three of these are described
below.
CATALYTIC COMBUSTION
One advanced concept that appears capable of achieving very low pollutant levels
is catalytic combustion in which a catalyst is used in place of a diffusion flame burner
to achieve the major energy release in a combustion system. The initial applicability is
to clean gaseous and vaporizable liquid fuels as a premixed fuel and air stream must be
presented to the catalyst. Oxidation of the fuel through both heterogeneous surface
reactions and homogeneous gas phase reactions occurs within the channels of the
catalyst bed at essentially adiabatic temperature. Complete combustion can be achieved
at very short residence time and with very high volumetric heat release rates. The two
apparent limits are (a) the temperature at which catalyst degradation becomes
significant, and (b) the well known kinetic threshold temperature above which the rate
of thermal NOX formation becomes significant. Therefore the application of the
technology to stationary combustion sources requires new system designs to achieve
long life and high thermal efficiency.
The graded cell catalyst has been developed during the program and patented.
This concept uses large cells at the inlet end of the catalyst monolith to maintain
heterogeneous ignition at very high fuel throughput (space velocity) with progressively
smaller cells to complete the fuel oxidation. This concept has been tested versus a
conventional straight cell catalyst of the same formulation. The graded cell catalyst
achieved three times the volumetric energy release of the straight cell and had a much
more uniform axial temperature profile. In addition, other versions of the graded cell
have shown extremely high heat release capability (>108 Btu/hr/ft3/ATM) and low
thermal NOX (<50 ppm at 1700°C). The graded cell catalyst appears to be a major
improvement in combustion catalyst technology.
FUEL NITROGEN
CONVERSION
There has also been significant progress in the development of systems for
application of catalytic combustion to boilers burning nitrogen containing fuels. A
catalytic staged combustor has been designed and tested, using the configuration shown
in Figure 16. The first-stage bed is run fuel rich to partially oxidize the fuel and to
promote formation of N2 from fuel nitrogen compounds. Heat is removed between
stages to reduce the adiabatic temperature in the second stage. Then the balance of
the air is added and the fuel oxidation is completed in the second stage catalyst. This
configuration allows the overall system to operate at minimum excess air for high
efficiency without exceeding the allowable temperature in either catalyst bed. The
conversion of fuel nitrogen to NOX is shown in Figure 17. The first stage was operated
at three levels of theoretical air (50 percent, 60 percent, and 70 percent) while the
overall theoretical air was varied from 60 percent to 150 percent. With 50 percent
first-stage air, the oxidizable nitrogen levels (2XN=HCN+NH3+NO) were relatively
insensitive to the overall air with a weak minimum below 30 percent conversion
around 100 percent theoretical air. When the primary was operated at a more optimum
condition (60 percent to 70 percent theoretical air) the EXN decreased to below 10
percent. Other studies of fuel nitrogen conversion show that the level attainable is
strongly dependent on the catalyst as well as the operating conditions. Low thermal
NOX coupled with minimum fuel nitrogen conversions make catalytic combustion an
attractive technique where very low emissions are required. Development of improved
catalyst and auxiliary system components is in progress. These components will be
integrated into several prototype systems for laboratory evaluation of the performance
of catalytic combustion in various applications.
92
-------
I—FLOW
FIRST STAGE BED
HEAT REMOVAL T / SECOND STAGE BED
ADDITIONAL AIR
FIGURE 16-Catalytic staged combustor
100
o
60
40
CJ
20
_ + ONE-STAGE COMBUSTION
§ A 50 PERCENT FIRST STAGE THEORETICAL AIR
g • 60 PERCENT FIRST STAGE THEORETICAL AIR
-1 • 70 PERCENT FIRST STAGE THEORETICAL AIR
50
FIGURE 17—Fuel nitrogen conversion staged
100
OVERALL THEORETICAL AIR, PERCENT
150
93
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HOMOGENEOUS REDUCTION
FLUE GAS TREATMENT
The homogeneous noncatalytic selective reduction of NOX with NHs occurs in
the presence of oxygen at temperatures around 1300K. The temperature window can
be lowered by the addition of hydrogen. This technique is a proprietary process that
has been evaluated in oil- and gas-fired systems both in the laboratory and in field
operating boilers. NOX reductions from 40 to 60 percent have been reported for
practical systems. The EPA has conducted an analysis of the potential applicability of
the process as a supplement to combustion modification in coal-fired boilers. The
system requires a manifold for injection of NH3/H2/carrier streams into the boiler
volume at the appropriate temperature window (normally in the superheater region).
Laboratory tests have shown 40 percent to 60 percent reduction in a coal-fired system
using practical NH3 levels. The main problem areas are (a) achieving uniform injection,
(b) maintaining the injection in the proper temperature window during load swings,
(c) ammonium sulfate deposition on convective surfaces, and (d) significant capital and
operating costs. The technique appears to be a potentially useful supplement to
combustion modification in Air Quality Control Regions where very stringent control
may be required.
In May 1978, two programs were initiated for the development of NOX flue gas
treatment for coal-fired systems. One program is for NOX control using Hitachi Zosen's
process which is based on selective catalytic reduction of NOX with NH3. The process
utilizes a metallic honeycomb catalyst arrangement for coal-fired applications. The
reactor is located between the boiler economizer and the air preheater and in front
of any particulate control device. The reaction temperature is in the range of 350°C to
420°C. The pressure drop is about 200-500 Pa. For 90 percent IMOX reduction, a
NH3:NO mole ratio of 1:1 is used. The process will be evaluated in a 2000 Nm3/hr
(0.5 electrical MW) pilot plant scale coal-fired source. The host site for the pilot plant
will be Georgia Power Company's Plant Mitchell near Albany, Georgia. Flue gas will be
obtained from Unit 3, a pulverized coal-fired Combustion Engineering boiler with a
nameplate rating of 125 MW.
EVALUATING UOP-SHELL
FUNDAMENTAL COMBUSTION
RESEARCH
The second program for simultaneous SO2/NOX control is evaluating the
UOP-Shell process. Briefly, the process employs two or more parallel passage reactors
using CuO as the sorbent for SO2 and using CuSO4 as the catalyst for the reduction of
NOX with NH3. A multiple reactor arrangement is needed to allow regeneration of
CuSO4 to CuO. Hydrogen is used as the reductant. The reactors are located between
the boiler economizer and the air preheater and in front of any particulate control
device. The process operates at a temperature of 400°C during both acceptance and
regeneration cycles. The cycles will be controlled for 90 percent removal of both
NOX and S02- For 90 percent NOX reduction, a NH3:NO mole ratio of 1:1 is used.
The process also will be evaluated in a 2000 Nm3/hr pilot plant coal-fired source. An
existing pilot plant, previously used by UOP to evaluate S02 removal, will be modified
for simultaneous removal of NOX and SO2- The host site for the pilot plant will be
Tampa Electric Company's Big Bend Station in North Ruskin, Florida. Flue gas can be
obtained from Unit 1 or 2 which are Riley-Stoker pulverized coal-fired boilers with a
nameplate rating of 400 MW each.
TVA has performed a preliminary economic evaluation of NOX and NOX/SOX
flue gas treatment processes for EPA. The base case was a new, 500 MW power plant
burning 3.5 percent sulfur coal and emitting 600 ppm NOX in the flue gas. The total
capital investments and annual revenue requirements for three dry NOX (selective
catalytic reduction) removal processes ranged from $32/kW and 1.9 mills/kWh to 3.4
mills/kWh, respectively. A dry process for simultaneous removal of both S02 and
NOX (UOP-Shell) had a capital cost of $132/kW and an annual revenue requirement of
6.3 mills/kWh.
The fundamental combustion research (FCR) program provides a synthesis of the
understanding of basic combustion phenomena in the context of practical combustion
systems. A number of aspects of the problem are currently being studied. To place the
FCR program in proper perspective, it is important to understand the relationship
between FCR and the more hardware-oriented technology development efforts being
pursued by Combustion Research Branch (CRB). The hardware-oriented technology
is based on current understandings of the complex interactions between flame chemis-
try, combustion fluid mechanics and the physical/chemical properties of fuels. The
94
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GAS PHASE REACTIONS
CHAR/NO
REDUCTION STUDIES
current level of understanding has proven sufficient to allow major advances in devel-
opment of control technology hardware. The various FCR activities are coupled to the
hardware development efforts through their focus on the key aspects of flame
chemistry, combustion aerodynamics and fuel processing.
A major focus of the program has been on developing a set of chemical kinetic
mechanisms to describe pollutant formation through gas phase reactions. The
developed reaction set has been checked against a wide variety of reactor experimental
results and is being used in what are termed limit case studies. Limit case studies
significantly simplify furnace aerodynamics by describing the flow field as
combinations of well stirred and plug flow reactors. By parametrically varying inlet
conditions, process variables, and reactor sequencing (i.e., inlet stoichiometry, heat
removal, etc.), such numerical studies help to identify the lower bounds of NOX
control which are set by the gas phase chemistry. These predictions can serve as a
standard for judging the effectiveness of developed control techniques and can suggest
various modifications of emerging control techniques to increase the effectiveness or
range of applicability.
The primary fuels of concern to EPA (in all phases of the program) are coal and
heavy fuel oils, including synfuels. A number of efforts within the FCR program
are addressing particular aspects of burning these fuels. MIT and Institut Francais du
Petrole have shown that coal char and soot (respectively) may play an important role
in determining exhaust NOX levels from furnaces and boilers. It has been shown that
both char and soot react with NO, even at low temperatures, and that such reactions
may represent an important step in determining exhaust NO levels and may even be
utilized to gain a significant level of emission control. MIT has applied for a patent
based on their EPA-sponsored studies of char/NO reduction.
Other studies are also being pursued to determine the rate of evolution and fate
of nitrogenous species as they evolve from coal particles or oil droplets. Results from
these studies are being directly used in the development of new low emission burners,
particularly heavy oil burners for package boilers. Identification of primary pyrolysis
products and speciation of secondary pyrolysis products may be the key to explaining
variations in the effectiveness of staged combustion as physical characteristics of fuels
are needed. An example of this is shown in Figure 18 where the achievable NOX
reduction with staged combustion is plotted versus a defined fuel nitrogen volatility.
The volatility is based on the fraction of the fuel nitrogen in the original fuel that
could be evolved as HCN during inert pyrolysis at 1373K. The highest HCN yield was
o
3
82
84
86
88
90
:
92
94
96
LEGEND
• PETROLEUM DERIVED
A SHALE DERIVED
I
35 40 45 50 55
FUEL NITROGEN VOLATILITY, PERCENT
60
65
70
FIGURE 18—Staging efficiency and fuel nitrogen volatility
95
-------
ENVIRONMENTAL
ASSESSMENT
TEST RESULTS
from the crude shale oil which gave a 93 percent reduction under staged-combustion
conditions. The reductions achievable from petroleum oils decreased as the fuel
nitrogen volatility decreased. Although the data are limited, this graph shows the
potential for correlation of the previously presented pilot scale data (Figure 12) with
results of fundamental experiments.
Several additional studies are being pursued to investigate aspects of furnace
aerodynamics. Turbulence, fuel ballistics, and numerical analysis of boiler type flow
fields are being considered. By incorporating the aerodynamics, gas phase chemistry,
and fuel chemistry studies into an integrated program package, significant input is
being made to development of emerging control technology and suggestions are
forthcoming on approaches to realizing advanced pollution control techniques.
The project for environmental assessment of NOX control technologies has
continued to evaluate all aspects of the problem associated with the application of
combustion modifications for the control of NOX emissions from stationary
combustion sources. The primary emphasis of this work has been the evaluation of the
environmental, economic, energy, and engineering implications of low NOX combustion
modification technology in order to provide comparisons with the environmental
impact of baseline (uncontrolled) operation.
Testing of seven combustion sources has been carried out using EPA's IERL-RTP
Levels 1 and 2 procedures for sample collection and analysis. The sources selected
for comprehensive testing included a 180 MW tangential coal-fired utility boiler, a
500 MW horizontally-opposed coal-fired utility boiler, a 740 MW opposed-wall oil-fired
utility boiler, two industrial stoker coal-fired watertube boilers, a blue flame oil-fired
warm air furnace, and a 60 MW oil-fired gas turbine.
Individual test reports are being prepared for each test site. Results for the
180 MW utility boiler showed that burners out of service and biased firing (staged
combustion modification techniques) yielded NOX reductions of about 37 percent and
30 percent, respectively, compared with the baseline level (490 ppm @ 3 percent 02
dry). A summary of the data is shown in Table 3. A slight increase in boiler efficiency
was observed and was attributed to lower excess air levels. Analysis of the results led to
the conclusion that the flue gas stream from this series of tests dominated the environ-
mental impact. Sulfur dioxide and NOX were the most significant gaseous species and
potentially hazardous levels of arsenic, barium, beryllium, iron and sulfur were present.
The solid effluents were estimated to be 1000 times less hazardous than the gaseous
effluents. The NOX controls employed were generally beneficial in reducing the flue gas
environmental impact since most species were either reduced or unaffected. Slight
increases were observed for nitrogen-containing (e.g., IMH3) and chloride species. There
was negligible impact associated with the combustion modifications on the composition
of the solid streams.
Detailed analyses on the other units tested are in progress. However, based on
overall considerations of the potential for adverse environmental impact, coal-fired
boilers have the highest priority for improved control for stationary combustion sources.
TABLE 3
Environmental assessment 180 MW coal fired utility boiler
Condition
Baseline
BOOS*
BIASt
Emissions
NO ppm
A
490
308
338
CO, ppm
29
27
30
Particulate ;itG/J
1.935
1.787
1.311
Burners out of service
t Biased firing
96
-------
SUMMARY
ACKNOWLEDGMENTS
The status of EPA's NOX control technology development program can be
summarized as follows:
• Based on projected fuel trends, NOX emissions may increase significantly with
current technology.
• More effective stationary source control technology can provide a means of
mitigating this emission trend.
• The combustion modification techniques under development offer the potential
for achieving significant NOX reductions without adverse effects on other pol-
lutants.
• These high levels of control can also be achieved at relatively low cost and
without degradation of thermal efficiency.
• If extremely low levels of NOX are required, advanced combustion technology
and supplemental techniques such as ammonia injection and flue gas treatment
are also under development.
The authors wish to thank W. S. Lanier, R. E. Hall and D. G. Lachapelle of the
Combustion Research Branch staff and J. D. Mobley of the Process Technology Branch
for contribution to sections of the paper.
97
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Stationary Sources (2nd Update). The Aerospace Corp. EPA-600/7-78-172a, NTIS
No. PB 282-428, June, 1978.
Kendall, R.M., and J.T. Kelly. Premixed One-dimensional Flame (PROF) Code User's
Manual. Acurex Corp./Energy & Environmental Division, EPA-600/7-78-172a, NTIS
No. PB 286-243, August, 1978.
Kesselring, J.P. Proceedings: Third Workshop on Catalytic Combustion (Asheville,
N.C., October, 1978). Acurex Corp., EPA-600/7-79-038, NTIS No. PB 293-336,
February, 1979.
Levy, J.M., J.H. Pohl, A.F Sarofim, and Y.H. Song. Combustion Research on the Fate
of Fuel-Nitrogen Under Conditions of Pulverized Coal Combustion. Massachusetts
Institute of Technology, EPA-600/7-78-165, NTIS No. PB 286-208, August, 1978.
Martin, G.B., and J.S. Bowen. "Control of Nitrogen Oxides from Combustion,"
Energy/Environment III EPA-600/9-78-022, NTIS No. PB 290-558, October, 1978.
McCandless, F.P., and K. Hodgson. Reduction of Nitric Oxide with Metal Sulfides.
Montana State University, EPA-600/7-78-213, NTIS No. PB 289-450, November,
1978.
Okuda, A.S., and L.P. Combs. Design Optimization & Field Verification of an Inte-
grated Residential Furnace Phase I. Rockwell Corp./Rocketdyne Div., EPA-600/7-
79-037a, NTIS No. PB 284-293, February, 1979.
99
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Pohlenz, J.B., and P.M. Nooy. Project Manual: Evaluation of UOP-Shell /VOX/SOX Flue
Gas Treatment Process. UOP Process Division (Draft Report: Publication Pending).
Salvesen, K.G., K.J. Wolfe, E. Chu, and M.A. Herther. Emission Characterization of
Stationary NOX Sources: Volume I Results. Acurex Corp./Energy & Environmental
Division, EPA-600/7-78-120a, NTIS No. PB 284-520, June, 1978.
Salvesen, K.G., M. Herther, K.J. Wolfe, and E. Chu. Emission Characterization of
Stationary NOX Sources: Volume II Data Supplement. Acurex Corp./Energy &
Environmental Division, EPA-600/7-78-120b, NTIS No. PB 285-429, August, 1978.
Spadaccini, L.J., J. McVey, J. Kennedy, A.S. Kesten, F.K. Owen, and C.T. Bowman.
Influence of Aerodynamic Phenomena on Pollutant Formation in Combustion (Phase II
Liquid Fuels). United Technologies Research Center, EPA-600/7-79-003, NTIS No.
PB 295-500, January, 1979.
Waibel, R.T., E.S. Fleming, and D.H. Larson. Pollutant Emissions from "Dirty" Low-
and Medium-Btu Cases. Institute of Gas Technology, EPA-600/7-78-191, NTIS No. PB
288-234, October, 1978.
Weiner, R.S., and R.R. Morcos. Project Manual: Evaluation of Hitachi Zosen NOX
Flue-Gas Treatment Process. Chemico Air Pollution Control Company. (Draft Report:
Publication Pending).
100
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tm^sm w%id&«i
^^&S *%-jffijpr ^
&
answers
Joseph D. Martinez
Institute for Environmental Studies
Louisiana State University
J. Lee Krumrne
Vinings Chemical Company
QUESTION
A/OX makes your eyes burn, but sulfur oxide can
kill you. There seems to be equally large artillery focused
on both, however. What are the comparative levels of
effort on the two in your work?
RESPONSE: Mr. Frank T. Princiotta (EPA)
There is a difference in maturity between the two
technologies. There are orders for about 60,000 mega-
watts of flue gas desulfurization systems. Many vendors
offer technologies that meet current and projected sulfur
oxide standards. That is not to say that more work is not
needed. Clearly, in the areas of reliability and waste
disposal, improvements are appropriate.
For nitrogen oxide, however, there are no meaning-
ful regulations, particularly for stationary sources. This is
true primarily because most of the regulations, such as
the New Source Performance Standards, are based on
technology, and frankly, there is no effective technology
for nitrogen oxide today. This is a major thrust of the
Research Triangle Park Nitrogen Oxide Control Program.
The question of relative environmental damage
from sulfur oxide and nitrogen oxide is a difficult one.
EPA, in the Clean Air Amendments of 1970, identified
the criteria pollutants, those pollutants for which there
were health data, suggesting that there are health and
welfare damages associated with these pollutants above
a certain ambient or air concentration. These criteria
pollutants include nitrogen oxide and photochemical
oxidants, of which nitrogen oxide is a precursor. The
importance of nitrogen compounds as components of
acid rain is expected to increase over the next 10 to
20 years. There is evidence that nitrogen oxide can
damage the lung. Because of this and the fact that it
is one of the precursors of photochemical smog, we
are concerned. EPA is now in the final stages of con-
sidering a more stringent ambient nitrogen oxide standard
101
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related to short-term exposure. Quite a bit of data indi-
cate that high-level, short-term exposure to N02 is par-
ticularly deleterious to lung function. There is a good
chance that a relatively stringent standard will be set. A
body of health data suggests that NO2, alone is a primary
problem.
QUESTION
The throw-away SO2 systems were more or less
bypassed in this discussion. Has there been any recent
development in these systems other than the use of soda,
ash, and caustic soda, particularly in relation to disposal
products and landfill?
RESPONSE: Mr. Michael A. Maxwell (EPA)
Forced oxidation is aimed directly at improving
the disposal properties of the throw-away processes.
The gypsum produced is a much more desirable end
product because of its ultimate settled solids, its chemical
oxygen demand, the probability that it can be landfilled,
and the probability that it can be stacked similar to
gypsum from the phosphate industry. In addition, over
the last several years, there has been much work on
commercial fixation processes whereby the sludge is
stabilized or fixed with either fly ash or an additive such
as lime. Yes, there has been quite a bit of work in waste
disposal characterization and improvement. In fact,
other than improvements in performance and reliability,
this has been the primary emphasis in the throw-away
program. The dual alkali method is an additional throw-
away process involving soluble sodium scrubbing. It
provides a calcium sulfite product for disposal similar to
the lime and limestone system.
102
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NEW DEVELOPMENTS IN FINE PARTICLE CONTROL
James H. Abbott
Leslie E. Sparks, Ph.D.
Dale L. Harmon
Dennis C. Drehmel, Ph.D.
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
L £ Sparks. Pb D
PARTICULATE COLLECTION
DEVICES
PATB R&D
SUBDIVISIONS
Particulate emissions are usually collected from an industrial smoke stack by
one or more types of three conventional devices: fabric filters, wet scrubbers, and
electrostatic precipitators (ESP). The design of each of these three devices has until
recently remained relatively unchanged since the turn of the century. In recent years
because of the need to collect smaller and smaller particles, meaning higher and
higher collection efficiencies, many improvements have been developed for the
conventional devices, and a number of novel devices and/or concepts have been
proposed, developed, and/or marketed.
As the requirement to collect finer and finer particulate has been imposed, the
cost of conventional particulate control has risen. Since many important collection
mechanisms become much less effective on fine particles (particles less than 1-3
^m in diameter), conventional devices (with the exception of fabric filters) have
become larger or have required more energy to operate and thus have become more
expensive. In order to minimize the impact of these increased costs on our national
clean air policy, the Environmental Protection Agency (EPA) has supported a
research and development (R&D) effort aimed at (1) developing and demonstrating
improvements to reduce the cost and increase the efficiency of conventional devices,
(2) solving special particulate control problems having wide national implementations,
such as those associated with the use of low sulfur coal and the increased use of
diesel powered autos, (3) evaluating existing novel devices, and (4) discovering
and bringing to a commercial feasibility stage devices based on new collection
principles or concepts of new combinations of existing concepts.
The Particulate Technology Branch (PATB) of EPA's Industrial Environmental
Research Laboratory, located at Research Triangle Park, North Carolina, for the past
5 years has had the major responsibility for carrying out the R&D effort mentioned
103
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above. Listed below are the currently most active and perhaps most important
subdivisions of this particulate R&D program:
« Development of Technology for Control of Particulate Emissions From the
Combustion of Low Sulfur Coal (Electrostatic Precipitators, Fabric Filtration,
and Flue Gas Conditioning).
• Fugitive Emission Control for Particulate Sources.
• Development and Transfer of Particulate Control Techniques to Mobile Diesel
Emissions.
• Determination of Emission Factors for Inhalable Particulate Ambient Standard.
• New Idea Identification and Evaluation (Novel Device Evaluation).
• New Particulate Control Technology Development (Novel Concepts).
In a two-stage ESP, particle charging occurs principally in the first stage, or
precharger, where electric current densities are high. Particle collection occurs in the
second stage, or collector, which would be designed to operate at relatively low
current density and high electric field strength. Thus, it is in the precharger that
back-corona caused by high electrical resistivity poses the greatest difficulty. The
EPA/SoRI precharger differs from other prechargers under development because
back-corona effects are overcome by electrical means and no special effort is made
to keep high resistivity dust from collecting in the precharger. The decision to
overcome high resistivity effects was made after laboratory experiments showed that
a monolayer of high resistivity dust was sufficient to defeat the purpose of the
precharger (1).
5.2
30
$103/M3/S
10.4
20
26
31.5
120
40 60 80 100
M2/M3/S SPECIFIC COLLECTOR AREA
FIGURE 1-Efficiency versus estimated size and capital cost of electrostatic precipitators
104
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SUPPRESSION
OF BACK-CORONA
The precharger design for suppression of back-corona is based on a simple
wire-plate electrode geometry, with the addition of perforated screen electrodes
parallel to the plates, as illustrated in Figure 2. A high voltage applied to the corona
wire will bring about corona conduction. In general, part of the current will go to
the plate and part to the screen, depending on the relative potential at each. If the
plate is grounded and the screen is set at a potential having the same polarity as
that of the corona wire, ions moving toward the plate will be repelled from the
screen. If the magnitude of the potential at the screen is great enough, the screen
current may go to zero, while a considerable corona current passes through the
openings in the screen, proceeding from the corona wire to the plate. If a high
resistivity dust is introduced into the system, some of the dust may be precipitated
on the plate electrodes. Very little dust will be deposited on the screen, because
the charge on the particles will be the same as that of the screen, and hence there
will be a repulsive force between the particles and the screen electrodes. If enough
dust builds up on the plate electrode, back-corona may occur. The ions resulting
from back-corona will have polarity opposite from that of the screen, so that in
moving away from the plate they will be attracted by the screen and captured.
Thus, the ion density in the space bounded by the screen electrodes can remain
mss
w
r
ft! i!
S!
Sii
105
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NONOPTIMUM
COLLECTOR STAGE
essentially unipolar, even if a substantial amount of back-corona activity occurs at
the plate electrodes. Additional information on the precharger is given by Pontius
and Sparks (2).
Pilot plant experiments of the two-stage concept, with a nonoptimum collector
stage, have been described by Sparks, et al (3). Their results for high resistivity dust
are shown in Figure 3. Economic projections based on the pilot plant data show
that even with a nonoptimum collector stage the two-stage system should result in a
factor 2-1/2 to 3 reduction in ESP capital cost. Optimizing the downstream collector
should result in even lower costs and enable us to meet the objective. A 10 MW
pilot demonstration of the precharger/collector system is being started. System
design has been finalized and startup is expected in early 1980.
1.0
8 °-5
P 0.4
cf 0.3
111
01
0.
0.2
0.1
— \ \ \ \
f
I.I 1 I
PRECHARGER OFF
SCA = 25 m2/m3/s
p^ 2 X 1012 ohm-cm
I I I I I I I I I I
0.1 0.2 0.3 0.40.5 1.0 2.0 3.0 4.05.0 10
PARTICLE DIAMETER,
FIGURE 3—Graded penetration curve showing effect of precharger
FABRIC FILTRATION
Although fabric filters have been successfully used to control particulate
emissions from small boilers, they have not been used in the U.S. to control
particulate emissions from large utility boilers because of the large size of filter
systems, the apprehension about fabric durability and mechanical design, and the
lack of familiarity with fabric filter technology by utilities. For these reasons most
utilities will probably not use fabric filters until they are demonstrated on a large
scale—even though fabric filters appear to be economically attractive for low sulfur
coal applications.
A contract has been funded with Southwestern Public Service Company
(SWPS) to provide the needed full scale demonstration of a fabric filter for control
of particulate on a large utility boiler burning western low sulfur coal. A new
baghouse began operation in June 1978 on a 356 MW boiler at the Harrington
Station of SWPS in Amarillo, Texas. In FY-79, three 1-month detailed emission
tests are scheduled to be completed to characterize this fabric filter. The contract
will continue until 1984 in order to determine the technical and economic feasibility
and the long term reliability of the fabric filter. Preliminary data indicate that
particulate emissions are acceptable. However, bag cleaning and system pressure
drop problems do exist. Work is underway to resolve these problems. In spite of
these problems the costs of fabric filters appear to be reasonable when compared to
other conventional technologies for many low sulfur coal applications.
106
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FLUE GAS CONDITIONING
FUGITIVE EMISSION
CONTROL
Particle collection by ESP's can be improved by introducing chemicals into the gas
stream which alter the electrical properties of the gas, the electrical resistivity of the
dust, or some other property of the dust. Sulfur trioxide (803), ammonia, and
proprietary chemicals are commercially available conditioning agents. PATB has
initiated a program to determine the effectiveness and possible environmental impact
of flue gas conditioning. PATB is also sponsoring a demonstration of sodium
conditioning. Results, to date, of these two efforts are discussed below.
Field test evaluation of available conditioning agents has shown that SOg is
an effective flue gas conditioning agent which reduces the electrical resistivity of
fly ash (4,5). Field tests of a proprietary agent do not show any improvement in
ESP performance (5). The field data also show that 863 conditioning can result in
significant emissions of 803. This 803 can condense in the atmosphere and form a
visible plume.
Laboratory studies indicate that triethylamine, which is used in Australia, can
react with flue gas components to form significant amounts of nitrosamine.
The demonstration of sodium conditioning follows successful pilot studies. The
full scale demonstration is now underway. Preliminary data disclosed mechanical
problems associated with distribution of the sodium carbonate/fly ash mixture in the
gas stream and on the ESP collector plates. Steps were taken to correct these
problems during a recent boiler outage. Data on the system following the boiler's
return to service are not available. This demonstration will be completed by late
1979.
Among the standards used by EPA to prevent adverse health and ecological
impacts of air pollution is the National Ambient Air Quality Standard (NAAQS).
The NAAQS is currently expressed in a number of ways involving the limitation of
total suspended particulate (TSP). Unfortunately, the TSP standard is not being
met in many air quality control regions. Fugitive dusts account for most of this
problem. In 9 out of 10 control regions, fugitive emissions are greater than ducted-
point source emissions. In one out of three control regions, fugitive emissions are
more than 10 times greater than ducted-point source emissions (6). Within cities
the contribution of point sources is expected to be smaller than fugitive emissions.
In Philadelphia, more than one-third of the TSP was attributed to reentrained street
dust and vehicular traffic; point sources were responsible for less than one-fourth of
the TSP.
ROAD CARPET
Because of the importance of fugitive sources in meeting NAAQS, PATB
has begun a program of control technology R&D. Described below are two ongoing
projects which have been labeled new concepts. This term doe not imply that such
technology has not been previously investigated but rather that the technology has
not been fully utilized and will remain new until it is accepted into conventional
practice. The two new concepts described here are road carpet and the spray charge
and trap (SCAT) system.
The fundamental concept behind use of a fabric roadbed stabilizer, or road
carpet, for control of fine particle emissions from unpaved roads is prevention of
vortex entrainment by separation of fine roadbed materials from the coarse aggregate
where the traffic movement occurs. Large aggregate is held from settling, while
newly deposited fines (< 70 /am) are filtered by gravitation and hydraulic action
down to a zone away from vortex entrainment. Road carpet can be made from
spunbonded, thin-film polypropylene on nylon sheet (Celanese), continuous filament
polyester fibers needled to form a highly permeable fabric (Monsanto), or other
spun or needle-punched synthetic materials. The mechanical interlocking of fibers
makes a formed fabric with the durability and toughness required for the proposed
use. Designed for road construction use, this fabric is laid over poor loadbearing
soils to help support and contain the overburden aggregate. It spreads concentrated
stress from heavywheeled traffic over a wider area, siphons away ground water, and
contains fine soil particles in the roadbed that can otherwise contaminate ballast or
road overburden.
107
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SPRAY CHARGE
DIESEL PARTICULATE
CONTROL
Air Pollution Technology, Inc. is studying the second concept, use of the
scrubber systems approach in controlling fugitive process emissions (FPE). Figure 4
is a functional diagram for the process anticipated for controlling FPE. The
functional phenomena represented in this diagram could occur concurrently or
separately in several types of equipment. The control concept is basically a three
step process:
• Containment of the FPE with electric or air curtains.
• Treatment with sprays which have electrostatic charge or surface active agents.
(When electrostatic charge is used the control concept is the SCAT system.)
• Removal of the droplets in an entrainment separator. PATB has planned an
extensive research, test, and evaluation program for both of these concepts.
The research portion will identify parameters affecting the theoretical and
economic limitations to utilization of the technology. Preliminary studies of these
parameters will provide an understanding for optimization. In the case of road
carpet, the vortex entrainment, comminution, and saltation of material on the
coarse aggregate must be modeled. Parameters affecting performance may be size and
thickness of the aggregate. For the scrubber system using charged water sprays,
methods of partial containment of the FPE must be studied as well as fundamentals
of droplet/particle interactions.
EPA's Office of Air, Noise, and Radiation, in response to the 1977 Clean Air
Act Amendments, is preparing particulate emission standards for light duty diesels
in 1981 and heavy duty diesels in 1983. Uncontrolled emissions are approximately
as great as 1 gram per mile and the proposed standard for light duty diesel in 1981
is 0.6 grams per mile. A further reduction for light duty diesels in 1983 has been
proposed which would set the emission limit at 0.2 grams per mile. In light of the
lead time necessary to set standards and to change engine production, these
proposed standards require the immediate identification and verification of candidate
control technologies. Moreover, biological assays have shown diesel particulate to be
mutagenic and hence potentially carcinogenic. Should further testing verify this
hazard and U.S. auto manufacturers continue to plan for conversion to diesel cars to
meet corporate average fleet fuel economy requirements, even stricter controls may
be necessary.
NEW CONCEPTS
Consequently, PATB has been intensively searching for and reviewing potential
control technology approaches. It has been determined that control of diesel
particulate is possible with an aftertreatment control device called the Aut-Ainer.
According to PATB's Japanese technology transfer contractor, Senichi Masuda, this
device is being developed in conjunction with Mitsubishi Motor Company, Inc.
Reported collection efficiencies range from 65 percent to 90 percent. The device
works by expansion of the exhaust gas through a throttle plate and collection on a
metal fiber mat. The filter may be cleaned by flushing to a sump which is
periodically purged.
Other control approaches are being investigated which utilize technology
developed for stationary sources. While conventional configurations of scrubbers,
baghouses, and electrostatic precipitators cannot respond to limitations on space and
convenient disposal of collected particulate, new concepts involving conventional
devices can. The baghouse would become a pleated cartridge filter, the scrubber
would become a charged droplet scrubber, and the electrostatic precipitator would
become a two-stage precipitator with flushed collection plates. The latter two
concepts would remove particulates to a sump which could be periodically purged
as with the Japanese control concept. In the case of the pleated filter, the collection
media would be a felt ceramic and would be cleaned by combustion or catalytic
incineration. Review of these concepts is currently in progress to verify feasibility.
Later, bench scale designs will be tested in the laboratory using engine
dynamometers to provide the particulate source. Finally, there will be an attempt to
demonstrate control with a prototype device on a field tested vehicle.
108
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TEXT
WATER
DROPS
m -
Z
O
FUGITIVE
PARTICLE
EMISSIONS
CONTACT DUST
WITH SPRAYS
COLLECT DUST
ON DROPS
SEPARATE
— -DROPS-
FROM AIR
DISPOSE
OF
DUST
CLEAN
AIR
X
m
-D-
Z
DISPOSE OF
OR RECYCLE
WATER
FIGURE 4-Functional diagram for the major process steps involved in controlling fugitive
particle emissions with a charged drop system
INHALABLE PARTICULATE
AMBIENT STANDARD
In response to the Clean Air Act Amendments of 1977, EPA is considering an
ambient air standard for inhalable particles which have been defined as those having
aerodynamic diameters less than 15 jum. Consequently, it will be necessary to have
emission factors for inhalable particles to provide for implementation of the
standard. Particulate emission factors, as compiled in EPA Report AP-42
("Compilation of Air Pollutant Emission Factors"), estimate the emission of total
suspended particulates from uncontrolled sources. This current program is for
determining emission factors based on a cut-off size for inhalable particles for both
controlled and uncontrolled sources. To achieve the objectives of this program the
following steps have already been started:
• Development of sampling techniques to allow assessment of the particulate
characteristics based on the inhalable potential.
• Extrapolation of the existing data on particulate characteristics to the inhalable
size range where possible.
• Selection of sampling strategies for major sources based on national and
regional impact within budgetary constraints.
Since a fine particulate standard may also be desirable in the future as a
secondary standard, this program will continue with the development of necessary
109
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NOVEL DEVICE PROGRAM
measurement techniques and the testing of sources (both point and fugitive) in
support of an inhalable particulate primary ambient standard and a fine particulate
secondary standard. This data will be used for the development of state implementa-
tion plans (SIP's) necessary to the implementation of these future proposed
standards.
The objective of lERL-RTP's novel device program is to identify and evaluate
new technology or new combinations of well studied mechanisms in order to achieve
cost effective control of fine particulate. A novel particulate collection device is a
device or a dust collection system based on new collection principles or on radical
redesign of conventional collectors which are available for testing as pilot or full
scale units. In the fall of 1973 the novel device evaluation program was initiated to
identify, evaluate, and develop, where necessary, those devices or systems which
showed the most promise for high efficiency collection of fine particulate. More
than 40 novel particulate collectors have been identified. About half of the devices
identified have been of sufficient interest to justify technical evaluations. To date
14 devices have been either field or laboratory tested:
1.0
I I
o
z
o
<
cc
I-
UJ
z
01
O.
0.1
0.01
0.001
0.1
1.0
AERODYNAMIC DIAMETER,
FIGURE 5—Penetration vs. particle size for novel devices tested by EPA
110
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HIGHEST OVERALL
EFFICIENCY
Braxton—Sonic Agglomerator
Lone Star Steel-Steam-Hydro Scrubber
R. P. Industries—Dynactor Scrubber
Aronetics—Two Phase Wet Scrubber
Purity Corporation—Pentapure Impinger
Entoleter—Centrifield Scrubber
Andersen 2000-CHEAF
Rexnord-Granular Filter Bed
Air Pollution Systems—Electrostatic Scrubber (Scrub-E)
Air Pollution Systems—Electro-Tube
Century Industrial Products-FRP-100 Low Energy Wet Scrubber
American Precision Industries—Apitron
Particulate Control Systems—Electrified Bed
Ceilcote—Ionizing Wet Scrubber
Fractional penetration curves for these devices are shown in Figures 5 to 7. Of
all the devices tested, the American Precision Industries' Apitron gave the highest
overall mass efficiency and fine particle fractional efficiency—99.9991 percent mass
1.0
o
s
H-
tai
z
o
I-
cc
z
01
a.
0.1
0.01
0.001
^ I I I IT IITTH I TT III HIM
APS ELECTROSTATIC SCRUBBER
APS ELECTRO TUBE
CEILCOTE IONIZING SCRUBBER
UW ELECTROSTATIC SCRUBBER
ELECTRIFIED BED
0.1
1.0
AERODYNAMIC DIAMETER, MmA
FIGURE ^-Penetration vs. particle size for electrostatically augmented novel devices
tested by EPA
111
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efficiency on a redispersed silica dust (8). Collection efficiency on particles between
0.25 /urn and 2 /urn was greater than 99.9 percent. The Apitron is an electrostatically
augmented fabric filter. Without the electrical energy being applied, the collection
efficiency was still high—99.997 percent; however, the pressure drop increased by a
factor of 3.
10
,-2
icr
o
O
LU
Z
.
o- 10"
10'
I I I
WITHOUT ESP POWER
WILL FULL ESP POWER
-5 _ I I I I I I I I I I I
AERODYNAMIC DIAMETER, jumA
FIGURE 7—Penetration vs. particle size for Apitron unit operating as a conventional
fabric filter and with full ESP power
SCRUBBER EFFICIENCY
Of the scrubbers tested, the Lone Star Steel Steam-Hydro Scrubber gave the
highest efficiency on fine particulate—99.9 percent efficiency on a fine fume from
an open hearth steel furnace. However, intrinsic power consumption is quite high, an
order of magnitude greater than an ejector venturi scrubber. If fuel must be
purchased to make the steam, the Steam-Hydro system is not an economic
alternative to such systems as fabric filtration or electrostatic precipitation. If
sufficient waste heat is available, the Steam-Hydro system becomes economically
feasible (9). The Aronetics Scrubber is similar to the Steam-Hydro Scrubber but
instead of steam it discharges high-pressure/high temperature (200°C) water through
a nozzle to provide small high-velocity water droplets. The Aronetics unit, tested
112
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NOVEL CONCEPTS PROGRAM
on a ferroalloy plant, was not quite as efficient as the Steam-Hydro unit (10). The
Air Pollution System (APS) electrostatic scrubber was equal in fractional collection
efficiency to a venturi scrubber using 2-1/2 times as much energy (11). This system
will be discussed in more detail later. The Ceilcote Ionizing Wet Scrubber was
similar in performance to the APS Electrostatic Scrubber. The APS Electro-Tube,
which is similar to a wet-wall ESP, gave some very high collection efficiencies on
fine particles— as high as 98.9 percent on 0.5 ;Um particles. This performance is
similar to that which can be achieved in small wet ESP's with the same ratio of
plate area to volumetric flow rate as the Electro-Tube unit tested (8).
The major difference between the Novel Device and Novel Concepts program
areas is that the device program deals with existing equipment which is either
offered commercially or available for pilot scale testing and the concepts program
deals with the development of equipment from untried ideas or from the results
of proven research which shows that the development of an idea is feasible.
Most work to date has been directed toward combining electrostatic removal
mechanisms with scrubbing or filtration mechanisms. The first area to be developed
was charged droplet scrubbing, with a feasibility study at M.I.T. (12) and a pilot
demonstration at TRW on a Kaiser coke oven (13). Electrostatics and filtration have
been studied at both Battelle Northwest (14) and Carnegie-Mellon (15,16)-the
former with bed filters, the latter with baghouses. At least two new concepts, a
ceramic membrane filter and a magnetic fiber bed, are oriented toward cleanup of
high temperature gases (1000-2000° F/500-1100°C). Other new concepts which have
been studied are foam scrubbing and pleated cartridge filters of a novel material.
Of the advanced electrostatic collection concepts studied, those employing
water droplets or filters have demonstrated enhanced performance and should be
considered for future applications. Electrostatic collection with water drops shows
high removal efficiencies for 0.5 jum particles which are difficult to capture.
Electrostatic collection with filters shows the potential for operation at either lower
pressure drops or higher filtration rates. Some electrostatic collection concepts are
given in Table 1. In general, the entries in Table 1 reflect the three major categories
of collection mechanisms: electric field effects, scrubbing, and filtration. For the last
two, combining electrostatic effects and conventional mechanisms enhances
performance over conventional devices of the same type. The possibility of enhanced
performance stimulated EPA's involvement in developing advanced electrostatic
collection concepts. Two of the demonstrations discussed in the next section are
based on electrostatic collection concepts.
TABLE 1
Electrostatic collection concepts
Concept
Collection
by means of
EPA Activity
Electrostatic Scrubbing Electric field and
water droplets
Charged Droplet
Scrubbing
Water droplets
Electrostatic Fiber Filter fibers
Beds
Contract 68-02-0250, MIT
Contract 68-02-1345, TRW
Grant 803278, University of Washington
Grant 804393, University of Washington
Contract 68-02-2666, Air Pollution System
Grant 801581, Battelle Northwest
Electrostatic Effects Filter fabric
in Fabric Filters
Grant 803020, Carnegie-Mellon University
113
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SUMMARY
NEW PROGRAMS
Three particulate collection systems, identified and/or developed under the
Novel Device and Novel Concepts Programs, are being demonstrated by EPA at pilot
scale. These systems are the University of Washington (UW) Electrostatic Scrubber,
the Air Pollution Systems (APS) Electrostatic Scrubber (Scrub-E), and the High
Gradient Magnetic Separator (HGMS).
In summary we will briefly discuss where each of the major research areas
stands and also describe some of the unresolved problems in each area.
The Low Sulfur Coal Program is a mature program and has several projects in
the demonstration phase. We fully expect to meet the program objectives of:
• Reducing capital cost of ESP by a factor of 3 to 5.
• Demonstrating that fabric filters are a cost effective method of particulate
control.
• Assessing the environmental impact of flue gas conditioning agents.
Some major unresolved problems in the low sulfur program area are:
• What is the least costly method of controlling particulate and sulfur oxide
emissions?
• What technologies are most applicable for meeting prevention of significant
deterioration requirements?
• What is needed to meet opacity standards?
The Fugitive Emission Program is relatively new. The two fugitive emission
control concepts discussed in this paper promise significant improvements in
controlling fugitive emissions. Additional research and development is needed to
develop more technology for fugitive emission control.
The Novel Device and Novel Concepts Programs are mature programs. Several
commercial devices have been evaluated. Three concepts have been developed to the
pilot or full scale demonstration phase.
The Inhalable Particulate Program is brand new. We expect to start field work
to acquire data for emission factors this month. As the program develops, we expect
to identify areas where particulate control technology is needed and will plan the
research needed to develop the required control technology. The diesel emission
program is also new.
We plan to begin the testing of devices for tailpipe exhaust gas cleanup in
November of this year.
114
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References
1. Pontius, D. H., L. G. Felix, J. R. McDonald, and W. B. Smith. "Fine Particle
charging Development." EPA-600/2-77-173 (NTIS No. PB 271-727/AS), August
1977.
2. Pontius, D. H. and L. E. Sparks. "A Novel Device for Charging High
Resistivity Dust." J.APCA, 28, 698 (1978).
3. Sparks, L. E., G. H. Ramsey, and B. E. Daniel. "Particle Collection in an
Electrostatic Precipitator Preceded by EPA-SoRI Precharger." J.APCA in press
(1979).
4. Dismukes, E. B., and J. P. Gooch. "Fly Ash Conditioning with Sulfur
Trioxide." EPA-600/2-77-242 (NTIS No. PB 276-651/AS), December 1977.
5. Patterson, R., P. Riersgard, R. Parker, and L. Sparks. "Flue Gas Conditioning
Effect on Electrostatic Precipitators." Paper presented at Symposium on the
Transfer and Utilization of Particulate Control Technology, Denver, Colorado,
July 1978.
6. Carpenter, B. H., and G. E. Weant. "Fugitive Dust Emissions and Control."
In Symposium on the Transfer and Utilization of Particulate Control Tech-
nology: Volume IV. Fugitive Dusts and Sampling, Analysis and Characteriza-
tion of Aerosols. EPA-600/7-79-044d, pp. 63-84, February 1979.
7. Bradway, R. M., F. A. Record, and W. E. Belanger. "A Study of Philadelphia
Particulates Using Modeling and Measurement Techniques." In Symposium on
the Transfer and Utilization of Particulate Control Technology: Volume IV.
Fugitive Dusts and Sampling, Analysis and Characterization of Aerosols. EPA-
600/7-79-044d, pp. 377-390, February 1979.
8. Felix, L. G., and J. D. McCain. "Apitron Electrostatically Augmented Fabric
Filter Evaluation." EPA-600/7-79-070, February 1979.
9. McCain, J. D., and W. B. Smith. "Lone Star Steel Steam-Hydro Air Cleaning
System Evaluation." EPA-650/2-74-028 (NTIS No. PB 232-436/AS), April
1974.
10. McCain, J. D. "Evaluation of Aronetics Two-Phase Jet Scrubber." EPA-650/
2-74-129 (NTIS No. PB 239-422/AS), December 1974.
11. Calvert, S., J. Rowan, S. Yung, C. Lake, and H. Barbarika. "A.P.S. Electro-
static Scrubber Evaluation." EPA-600/2-76-154a (NTIS No. PB 256-335/AS),
June 1976.
12. Melcher, J. R., and K. S. Sachar. "Charged Droplet Scrubbing of Submicron
Particulate." EPA-650/2-74-075 (NTIS No. PB 241-262/AS), August 1974.
13. Krieve, W. F., and J. M. Bell. "Charged Droplet Scrubber for Fine Particle
Control: Pilot Demonstration." Report EPA-600/2-76-249b (NTIS No. PB
260-474/AS), September 1976.
14. Reid, D. L., and L. M. Browne. "Electrostatic Capture of Fine Particles in
Fiber Beds." EPA-600/2-76-132 (NTIS No. PB 260-590/AS), May 1976.
15. Penney, G. W. '"Electrostatic Effects in Fabric Filtration: Vol. I. Fields,
Fabrics, and Particles (Annotated Data)." EPA-600/7-78-142a (NTIS No. PB
288-576/AS), September 1978.
16. Frederick, E. R. "Electrostatic Effects in Fabric Filtration: Vol. II. Tribo-
electric Measurements and Bag Performance (Annotated Data)." EPA-600/
7-78-142b (NTIS No. PB 287-207/AS), July 1978.
115
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17. Pilat, M. J., and G. A. Raemhild. "University of Washington Electrostatic
Scrubber Tests at a Coal-Fired Power Plant." EPA-600/7-78-177b (NTIS No.
PB 292-646/AS), December 1978.
18. Pilat, M. J., G. A. Raemhild, and A. Prem. "University of Washington Electro-
static Scrubber Tests at a Steel Plant." EPA-600/7-78-177a (NTIS No. PB 288-
307/AS), September 1978.
19. Water Reclamation Using SALA-HGMS™ Magnetic Separation Equipment and
Filtration Processes. Sala Magnetics, Inc., Cambridge, MA (1975).
20. Drehmel, D., and C. Gooding. "High Gradient Magnetic Particulate Collection."
AlChE Symposium Series, Volume 74, 1978.
21. Gooding, C., and D. Drehmel. "Application of High Gradient Magnetic
Separator to Fine Particle Control." J.APCA, May 1979.
116
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DISPOSAL OF WASTES FROM COAL-FIRED POWER PLANTS
Julian W. Jones
Industrial Environmental Research Laboratory/RTP
U.S. Environmental Protection Agency
Ju/ian IV Jones
COAL ASH PRODUCTION
COAL ASH UTILIZATION
Modern fossil-fueled, steam-electric generating plants present the full spectrum of
potential environmental problems—pollution of air and water and generation of large
quantities of solid waste. Essentially all of the solid wastes, except for bottom ash, are
generated by air pollution'control devices—mechanical collectors (e.g., cyclones), elec-
trostatic precipitators, baghouses, and scrubbers—to control emissions of fly ash and
sulfur dioxide (SC>2). Although there are other wastes, such as those from water
treatment systems, the quantities of these are small compared with the large amounts
of ash and SC>2 scrubber waste produced.
Coal ash production by electric utilities is expected to reach 65 million metric
tons per year, including over 45 million metric tons per year of fly ash, by 1980 (1).
U.S. electric utility commitments to S02 scrubbers, or flue gas desulfurization (FGD)
systems, currently total about 62,500 Mw of electrical generating capacity (2). Approx-
imately 10 million to 15 million metric tons per year (dry) of FGD wastes, exclusive
of fly ash, are expected to be produced by the mid-1980's, when all these plants are
onstream.
Extensive utilization of coal ash is both technically and economically feasible.
For example, fly ash can be admixed with Portland cement clinker in an ash:clinker
ratio as high as 1:5. With Portland cement production in the U.S. currently around
80 million metric tons per year, this means that approximately one-third of the 1980
fly ash production could be used for this single application. However, current utiliza-
tion of fly ash for all applications is just 13 percent of production, according to the
National Ash Association (3).
In 1975 Japan produced more than a million metric tons of gypsum by FGD
processes, primarily for use in wall board and Portland cement (4). TVA recently
117
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COAL ASH DISPOSAL
FGD WASTE DISPOSAL
completed a study for EPA which indicates that approximately two-thirds of the
gypsum requirements for the Portland cement industry in the U.S. could be supplied
by FGD systems in a competitive market (5). However, this use would consume only
about 20 percent of the FGD waste expected to be produced in the mid-1980's. On
the other hand, a shift to grass-roots wallboard plants near power plants, instead of
near natural gypsum delivery points, could increase this percentage substantially. The
wallboard industry currently consumes about 11 million metric tons of gypsum
annually, almost four times the annual consumption of the Portland cement
industry (5).
In any event, because of the current lack of market demand for coal ash and
FGD wastes, most electric utilities find disposal of these wastes the most attractive
choice. However, once the decision is made in favor of disposal, the environmental
and economic effects of the various disposal options have to be addressed.
Disposal of coal ash, either in ponds or landfills, has been practiced for many
years. Ash ponds at power plants overflow to watercourses in numerous locations.
Until recently, this was not of major environmental concern, very likely because the
major chemical constituents of fly ash (i.e., those comprising the greatest percentage
by weight) have very low solubility. However, both existing and pending regulations
on plant discharges and disposal of wastes on the land have caused a trend toward (a)
dry ash handling and disposal in a landfill or (b) codisposal of ash with FGD waste,
either in a zero-discharge pond with recycling of water to the plant or as part of an
FGD waste treatment process.
Initially, FGD waste was disposed of in ponds, usually along with fly ash from
the plant. However, FGD systems have been in the limelight since early in the period
of U.S. environmental awareness, and very early in their commercial history there was
concern about disposal of wastes from these systems because (a) the large amount of
occluded water in the wastes or sludges made them physically unstable; (b) the variable
physical and chemical properties of the wastes made them an "unknown" material; and
(c) the soluble and slightly soluble chemical constituents in the wastes made them
potential sources of water pollution. Consequently, considerable research and develop-
ment was undertaken by governmental and private organizations. These efforts have
resulted in a better understanding of the nature of FGD wastes and a trend toward
more environmentally acceptable and cost-effective methods of disposal, either in
ponds lined with clay or other low permeability material to reduce their potential for
water pollution or in a landfill, usually after chemical treatment of the waste to
improve its physical stability and reduce its permeability.
Other methods of coal ash and FGD waste disposal are currently being con-
sidered, including the return of these wastes for use in coal mine reclamation. At least
two plants, in North Dakota and Texas, are already disposing of the wastes in this
manner. Disposal in the ocean, possibly by construction of an artificial reef of treated
"blocks" of FGD waste and fly ash, is also being studied; the environmental accept-
ability of this method has not yet been demonstrated.
PRESENT REGULATORY
FRAMEWORK
Table 1 shows Federal legislation that applies to the handling and disposal of
coal ash and FGD waste in ponds, landfills, coal mines, and the ocean. The two legis-
lative Acts that have the greatest impact on disposal of these wastes are the Federal
Water Pollution Control Act (FWPCA) and the Resource Conservation and Recovery
Act (RCRA).
*
The FWPCA of 1972 established a system whereby all discharges to navigable
waters require a permit, issued by EPA or a state delegated the authority by EPA.
This Act also required industries to use beginning July 1, 1977, the "best practicable"
control technology currently available (BPCTCA) to control pollutant discharges, and
requires application of "best available" technology economically achievable (BATEA)
by July 1, 1983. EPA established national effluent guidelines, based on BPCTCA and
BATEA, for existing power plants, as well as New Source Performance Standards
(NSPS) for plants for which construction was initiated after the regulations were
proposed. Table 2 summarizes effluent guidelines and standards for steam-electric
power plant ash ponds.
118
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TABLE 1
Federal regulatory framework for disposal of coal ash and FGD waste
Possible Environmental
Impact
Legislation
Administrator
Surface Water Contamination • Federal Water Pollution Control Act of 1972 and
Amendments of 1977
Groundwater Contamination • Resource Conservation and Recovery Act of 1976
• Safe Drinking Water Act of 1974
Waste Stability/Consolidation • Dam Safety Act of 1972
• Surface Mining Control and Reclamation Act
of 1977
• Occupational Safety and Health Act of 1970
• Federal Coal Mine Health and Safety Act
of 1969
Fugitive Air Emissions
Contamination of Marine
Environment
• Clean Air Act
• Hazardous Materials Transportation Act of 1975
• Federal Coal Mine Health and Safety Act of 1969
• Occupational Safety and Health Act of 1970
' Marine Protection Research and Sanctuaries Act
of 1972
• Environmental Protection Agency
• Environmental Protection Agency
• Environmental Protection Agency
• Army Corps of Engineers
• Office of Surface Mining
Reclamation and Enforcement
• Occupational Safety and Health
Administration
• Mining Enforcement Safety
Administration
• Environmental Protection Agency
• Department of Transportation
• Mining Enforcement Safety
Administration
• Occupational Safety and Health
Administration
• Environmental Protection Agency
TABLE 2
Effluent guidelines and standards for power plant ash ponds
Discharge Stream
Controlled Parameter
BPCTCA*
BATEA*
NSPS*
All Plant Discharges
Bottom Ash Transport
Water
pH 6.0-9.0
polychlorinated biphenyls (PCBs) zero
6.0-9.0
zero
6.0-9.0
zero
30-day daily 30-day daily 30-day daily
average maximum average maximum average maximum
total suspended solids (TSS) 30
100
3CH-12.5t 10CH-12.5 30+20 100+20
Fly Ash Transport
Water
oil
oil
and
and
grease
TSS
grease
15
30
15
20
100
20
15+12.5
30
15
20+12.5
100
20
15+20
zero
zero
20+20
zero
zero
*AII quantities except pH are in units of mg/1.
t^-12.5 or -^20 indicates the required degree of recycle (or "number of cycles") of water;
-r12.5 means 8% blowdown allowed, while -^-20 means 5% blowdown allowed.
119
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CLEAN WATER ACT
GROUNDWATER
CONTAMINATION
SPECIAL WASTES
The FWPCA Amendments of 1977, or the Clean Water Act (CWA), require
review of the BATEA and the NSPS, particularly regarding the discharge of "priority
pollutants," 129 potentially hazardous pollutants, including heavy metals. The date of
BATEA compliance is a function of the type of pollutant and the level of treatment
possible. Changes to the regulations on ash pond discharges currently under consider-
ation include limitations on certain trace metals, zero discharge for bottom ash
(BATEA and NSPS), and possibly zero discharge for fly ash (BATEA). The modi-
fied regulations are expected to be proposed later this year.
No guidelines or standards have been promulgated specifically for FGD systems,
although the limitations for low volume waste streams are currently being applied. In
general, it is assumed that there will be no direct discharge from these systems. How-
ever, because of operational problems which require extra water, some of the com-
mercial FGD systems have entailed a discharge. Nevertheless, these systems were
designed to operate "closed-loop," that is, the only discharge of water would be that
associated with the FGD waste. In the more recent systems to come on line, this
design feature is operational.
With no direct discharge from FGD systems, the major environmental concern
associated with FGD waste disposal is the potential contamination of groundwater.
This can also be said of an ash pond with no discharge, or of disposal of ash in a
landfill. The major Federal legislation which addresses these potential problems is the
RCRA. Before enactment of the RCRA, there was no comprehensive Federal
authority to regulate disposal of wastes. This Act is designed to eliminate improper
disposal of wastes through Federal regulation of hazardous-waste* disposal and state
regulation (with Federal assistance) of nonhazardous solid waste disposal. The Act
defines a hazardous waste as a waste which poses a "substantial present or potential
hazard to human health or the environment" if improperly managed.
Regulations for the identification, handling, and disposal of hazardous wastes
were proposed in December 1978(6). The criteria for identifying hazardous wastes
include characteristics such as ignitability, corrosivity, reactivity (e.g., strong oxidizing
agents), and toxicity. The protocol for handling toxicity includes subjecting the waste
to an extraction procedure (EP), followed by chemical analysis of the extract for eight
trace metals and six pesticides. If the concentration of any of the metals or pesticides
exceeds 10 times the EPA National Interim Primary Drinking Water Standards, the
waste is considered to be hazardous.
The proposed regulations also included a list of wastes that EPA considers to be
hazardous. Neither coal ash nor FGD waste was on the list. However, EPA recog-
nized that some percentage of the coal ash and FGD waste might fail the toxicity
criteria because of excessive concentrations of one or more of the eight trace metals.
(Concentrations of these metals are primarily a function of the coal composition,
although they also vary with the type of FGC system and with operating parameters.)
Nevertheless, EPA also recognized that "such waste occurs in very large volumes, that
the potential hazards posed by the waste are relatively low, and that the waste is not
amenable to control techniques..." required under the Standards Applicable to Owners
and Operators of Hazardous Waste Treatment, Storage and Disposal Facilities (6). For
this reason, hazardous coal ash and FGD wastes are considered "special wastes" and
will very likely be subject to standards less stringent than the general hazardous-waste
disposal standards.
In the December 1978 announcement EPA indicated that proposed rules regard-
ing the treatment, storage, and disposal of special wastes would be published at a later
date. In the interim, however, many of the general facility standards (e.g., waste
analysis, security, recordkeeping, groundwater monitoring) will apply to these wastes.
120
*EPA may authorize state agencies to implement their own programs if the programs are deemed
equivalent to EPA regulations for hazardous-waste disposal.
-------
R&D WASTE DISPOSAL
PROGRAM
Coal ashes and FGD wastes that meet the toxicity criteria are not considered
hazardous (or special) wastes and therefore will be regulated under the nonhazardous
sections of RCRA. EPA is required by RCRA to issue regulations for nonhazardous
waste disposal, but the authority to implement and enforce these regulations rests with
the states. Each state may receive Federal assistance in this effort, if it adopts and
enforces the EPA regulations for disposal of nonhazardous waste.
In 1972, EPA initiated a major program of research and development (R&D) in
the area of FGD waste disposal. The primary objectives of the program were better
quantification of potential environmental problems associated with FGD waste disposal
and better assessment of FGD waste disposal technologies. Coal ash disposal alone was
not investigated under this initial program. However, since in most instances FGD
waste either contains fly ash (collected in the scrubber) or is mixed with ash prior to
disposal, any thorough study of FGD waste, such as was conducted under this pro-
gram, includes a study of fly ash. Because of this rather inseparable relationship
between FGD waste and fly ash, the term "flue gas cleaning (FGC) wastes" was coined
to cover both wastes.
In late 1974, plans were formulated to greatly expand EPA's FGC waste-related
R&D efforts as part of the Interagency Energy/Environment R&D Program. These
efforts included continuing to improve quantification of potential environmental
problems (of the 1972 program). They were also aimed at reducing costs, investigating
a broader range of alternative waste disposal options, and examining possible uses of
the wastes. The Interagency Energy/Environment R&D Program dealing with disposal
of power plant wastes is part of a larger program that involves control of waste and
water pollution. The Waste and Water Program, as the larger program is known, is
divided into four major areas:
• FGC waste disposal
• FGC waste utilization
• Effluent treatment
• Water recycle/reuse
Each of these program areas comprises a number of projects. These are listed in Table
3. The FGC waste disposal area of the Waste and Water Program consists of 20
projects, 7 of which were recently completed. In addition, three of the five water
recycle/reuse projects are directly related to FGC waste disposal. The discussion
which immediately follows describes some of the significant accomplishments of these
projects.
TABLE 3
Projects in the waste and water program
Project Title
Contractor/Agency
FGC WASTE DISPOSAL
Assessment of Technology for Control of Waste
and Water Pollution
* FGC Waste Characterization, Disposal Evaluation,
and Transfer of FGC Waste Disposal Technology
I Characterization and Monitoring of Full-Scale
Utility Waste Disposal Sites
Arthur D. Little, Inc.
The Aerospace Corporation
Contractor Not Yet Selected
'Project completed
tDirect support of regulation development
121
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Table 3 (Continued)
Project Title
Contractor/Agency
*t Solid Waste Impact of Controlling SC>2 Emissions
from Coal-Fired Steam Generators
Laboratory and Field Evaluation of 1st and 2nd
Generation FGC Waste Treatment Processes
Ash Characterization and Disposal
* Studies of Attenuation of FGC Waste
Leachate by Soils
* Establishment of Data Base for FGC Waste
Disposal Standards Development
Development of Toxics Speciation Model and
Economic Development Document for FGC
Waste Disposal
Shawnee FGC Waste Disposal Field
Evaluation
* Louisville Gas and Electric Evaluation
of FGC Waste Disposal Options
FGC Waste Leachate/Liner Compatibility Studies
Lime/Limestone Wet Scrubbing Waste Characterization
and Disposal Site Revegetation Studies
* Development of EPA Pilot Plant Test Plan To Relate
FGC Waste Properties to Scrubber Operating Variables
* Dewatering Principles and Equipment Design Studies
Pilot Demonstration of Advanced Gravity Settler
Conceptual Design/Cost Study of Alternative Methods
for Lime/Limestone Scrubbing Waste Disposal
Evaluation of FGC Waste Disposal in Mines and
the Ocean
t Evaluation of Power Plant Wastes for
Toxicity as Defined by RCRA
t Study of Nonhazardous Wastes from Coal-Fired
Utilities
FGC WASTE UTILIZATION
* Gypsum Byproduct Marketing Studies
Pilot Studies of a Process for Recovery of Sulfur
and Calcium Carbonate from FGC Waste
The Aerospace Corporation
U.S. Army Corps of Engineers
(Waterways Experiment Station)
Tennessee Valley Authority
U.S. Army Test and Evaluation Command
(Dugway Proving Ground)
Stearns, Conrad and Schmidt
Consulting Engineers, Inc. (SCS Engineers)
SCS Engineers
Tennessee Valley Authority
The Aerospace Corporation
Louisville Gas & Electric Co.
(Subcontractor: Combustion Engineering, Inc.)
U.S. Army Corps of Engineers
(Waterways Experiment Station)
Tennessee Valley Authority
Radian Corporation
Auburn University
Auburn University
Tennessee Valley Authority
Arthur D. Little, Inc.
Radian Corporation
Department of Energy
(Oak Ridge National Laboratory)
Radian Corporation
Tennessee Valley Authority
Pullman-Kellogg
'Project completed
tDirect support of regulation development
122
-------
Table 3 (Concluded)
Project Title
Contractor/Agency
Fertilizer Production Using Lime/Limestone
Scrubbing Wastes
* Use of FGC Waste in a Process for Alumina
Extraction from Low-Grade Ores
EFFLUENT TREATMENT
Characterization of Effluents from Coal-Fired
Power Plants
Treatment of Power Plant Wastes with
Membrane Technology
* Alternatives to Chlorination for Control
of Condenser Tube Biofouling
t Assessment of the Effects of Chlorinated Seawater
from Power Plants on Aquatic Organisms
*t Evaluation of Dechlorination for the Removal of Total
Residual Oxidants in Salt Water Cooling Systems
* Bromine Chloride—An Alternative to Chlorine for
Fouling Control in Condenser Cooling Systems
t Evaluation of Lime Precipitation for Treatment
of Boiler Tube Cleaning Waste
*t Assessment of Technology for Control of Toxic
Effluents from the Electric Utility Industry
*t Field Testing/Laboratory Studies for Development
of Effluent Standards for Electric Utility Industry
Effects of Pathogenic and Toxic Material
Transported via Cooling Device Drift
Assessment of Measurement Techniques for Hazardous
Pollution from Thermal Cooling Systems
Tennessee Valley Authority
TRW, Inc.
Tennessee Valley Authority
Tennessee Valley Authority
Monsanto Research Corporation
TRW, Inc.
TRW, Inc.
Martin Marietta Corporation
Hittman Associates, Inc.
Redian Corporation
Radian Corporation
H2M, Inc.
Lockheed Electronics Co.
Northrop Corporation
WATER RECYCLE/REUSE
* Assess Power Plant Water Recycle/Reuse
t Pilot Demonstration of Closed-Cycle Ash Sluicing
*t Water Pollution Impact of Controlling S02 Emissions
from Coal-Fired Steam Generations
Power Plant Cooling Tower Slowdown Recycle by
Vertical Tube Evaporator With Interface Enhancement
* Treatment of Flue Gas Scrubber Waste Streams With
Vapor Compression Cycle Evaporation
Radian Corporation
Radian Corporation
Radian Corporation
University of California - Berkeley
Resources Conservation Company
*Project completed
tDirect support of regulation development
123
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FCG WASTE
CHARACTERISTICS
CHEMICAL COMPOSITION
FGC WASTE DISPOSAL
TECHNOLOGY
The chemical characteristics of FGC scrubber waste have, to a large degree, been
quantified. FGC waste liquors have been shown to exceed drinking water standards
for total dissolved solids (TDS), with high concentrations of calcium, sulfate, and
chloride, and, in some cases, fluoride, magnesium, and sodium. In addition, concentra-
tions of several trace metals have been noted in excess of drinking water standards.
The chemical composition of FGC waste solids consists of calcium sulfite hemihydrate,
calcium sulfate dihydrate (gypsum) and/or hemihydrate, and calcium carbonate, plus
any fly ash collected in the scrubber. The percentage of each solid constituent is
primarily a function of the alkaline additive (e.g., lime, limestone), the sulfur in the
coal, and the manner in which the scrubber system is operated (e.g., whether forced
oxidation is applied, whether fly ash is collected separately). Although fly ash has
been shown to be a major contributor of trace elements to the waste solids and liquor,
separate collection of fly ash does not necessarily mean that concentrations of all these
elements in the waste liquor will be insignificant (7).
A compilation of existing data on coal ash, generated by TVA and others, was
issued in early 1977 (8). This report showed that a number of potentially hazardous
trace constituents tend to be concentrated in fly ash (as opposed to bottom ash).
Further efforts are currently under way to better define this preferential "partitioning"
of chemical constituents between fly ash and bottom ash, as well as the concentration
of specific constituents as a function of particle size. This latter information would be
especially significant in understanding the effect of the presence or absence of fly ash
on FGD waste liquor composition.
The physical properties of FGC waste vary considerably from system to system.
Chemical composition is related to, but does not adequately define, the size and type
of the solid crystals. For example, in comparing the lime and limestone scrubber
solids from the EPA/TVA Shawnee test facility, the limestone scrubber solids were
found to be primarily individual platelets or "rosette" aggregates, while the lime
scrubber solids were primarily spherical aggregates with somewhat better settling and
dewatering properties. However, the chemical compositions of the solids from both
scrubbers were quite similar.
Regardless of the chemical composition, when FGC wastes are not adequately
dewatered (or are allowed to "rewet" after dewatering), they tend to be physically
unstable, or fluid, with little or no compressive strength. This physical instability of
FGC wastes and the pollution potential of chemicals dissolved in the occluded water
are the two major environmental concerns associated with disposal of these wastes.
Several approaches for improving the physical stability of FGC wastes have been,
and continue to be, studied as part of a disposal method. A basic feature of all
approaches is the removal of sufficient water from the waste, either physically or
chemically (or by a combination of the two), to achieve physical stability. Occluded
water is more easily removed physically if the solid particles are large enough to settle
rapidly or if they provide a sufficiently porous structure for mechanical water removal
(e.g., filtration). Difficulty in physical dewatering of FGC wastes is normally attributed
to the small platelet crystalline structure of calcium sulfite. However, some forms
of calcium sulfite crystals are more easily dewatered than others, suggesting the possi-
bility of avoiding the less desirable forms by-proper scrubber operation.
At the present time, the relationship between the scrubber operating parameters
and the characteristics of the calcium sulfite crystals has not been adequately defined
although certain qualitative observations, such as the comparison between lime and
limestone scrubbers mentioned above, have already been made. For example, in lime-
stone scrubbing systems there appears to be an inverse relationship between sulfite
crystal size and limestone additive stoichiometry (9). In addition, in tests with lime at
Louisville Gas and Electric's Paddy's Run station, calcium sulfite crystals formed in a
large (high retention time) tank were mostly individual platelets, whereas crystals
formed in a small (low retention time) tank were primarily aggregates of platelets (10).
To better define the relationship between scrubber operation and calcium sulfite
crystals, crystal nucleation and growth were studied. This study resulted in a com-
puter model and a test plan for both completion of the model and definition of the
scrubber/crystal relationship (11). The tests will be conducted at the EPA/IERL-RTP
124
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DEWATERING EQUIPMENT
FIXATION PROCESSES
FGC WASTE DISPOSAL COSTS
pilot plant facilities later this year. We hope this testing will result in the development
of procedures for obtaining consistent, easily dewatered calcium sulfite solids.
A complementary approach to improving the quality of calcium sulfite solids
would be to improve the performance of dewatering equipment. Laboratory pilot-scale
testing using calcium sulfite waste from Louisville Gas and Electric has shown current
commercial gravity settling devices (clarifiers, thickeners) to be far from optimum. A
design approach has been developed whereby the clarification and thickening functions
of the gravity settler have been separated into two pieces of equipment, each of which
can be optimized for its function. The result is improved dewatering (thicker under-
flow) and satisfactory clarification (without using flocculants), with substantially
smaller and less expensive equipment. Current plans are to demonstrate this design
approach on a large pilot scale at TVA's Shawnee steam plant near Paducah, Kentucky.
Testing should be underway by September or October 1979. A paper describing the
laboratory pilot results was presented in June 1978 (12).
One way to avoid the dewatering problems associated with calcium sulfite
crystals in FGC waste is to use oxidation techniques to produce calcium sulfate or
gypsum (CaS04.2H20). Gypsum crystals are typically much larger and thicker than
sulfite crystals; therefore, they settle more quickly and trap less water upon settling.
Oxidation of the calcium sulfite outside of the scrubber system, although feasible, is
more expensive than oxidation within the scrubber loop, which is simpler and there-
fore less expensive. The latter approach has been successfully tested at the laboratory
and large field pilot levels (13), (14), and commercial systems are now being offered
by experienced suppliers. Forced oxidation of calcium sulfite to gypsum will be tested
on a commercial scale system at TVA's Widow's Creek steam plant.
Many utilities are currently choosing chemical treatment (sometimes called
fixation) processes to physically stabilize their FGC waste. Field testing these processes
under the EPA Waste and Water Program has shown that the treated waste exhibits
significant structural improvement, at least a 50 percent reduction in major solubles
(e.g., chloride) in the leachate, and an order of magnitude or more reduction in perme-
ability (15). Another advantage of chemical treatment is that coal ash can be codis-
posed of, along with the FGC waste.
Other stabilization/disposal techniques are being evaluated, such as underdrainage
and compaction of untreated FGC wastes and the production/disposal of gypsum. A
paper describing recent results of this evaluation was presented in June 1978 (16).
In areas with appreciable rainfall, the underdrainage approach appears to require
division of the disposal area into several sections; that is, over the life of the plant,
disposal would be accomplished one section at a time. For gypsum disposal in a pile,
considerable maintenance may be required because of surface cracking from
freeze/thaw cycles and/or erosion from rainfall (16).
Along with the technical/environmental evaluation of alternative FGC waste
disposal techniques, the costs of each technique have also been determined. Preliminary
estimates, in 1977 dollars, for a typical high-sulfur coal-fired plant have been recently
reported. These show ponding costs of about $5 to $8 per metric ton (dry solids,
including fly ash) and chemical treatment/landfill costs of about $10 per metric ton
(same basis as ponding) (17). More detailed cost estimates (in 1980 dollars), show
ponding costs of about $9 per metric ton and chemical treatment/landfill costs of
about $14 per metric ton (18). (It should be noted that the $14 figure includes all
dewatering equipment; the earlier $10 figure assumed the clarifier/thickener to be part
of the scrubber system. Clarifiers were excluded in both ponding cost estimates.) De-
tailed cost estimates (also in 1980 dollars) for direct landfill of FGC gypsum waste
(including fly ash) indicate a cost of about $11 per metric ton (19). These estimates
assumed that FGC gypsum wastes could be disposed of using normal landfill
techniques, an assumption that has not been commercially demonstrated. Estimates of
the costs of coal ash disposal by ponding and landfilling are currently under way.
A cost of $14 per metric ton for FGC waste disposal converts to about 1.5
mills/kWhr revenue requirement, which compares to a total FGC system revenue
requirement of about 5 mills/kWhr. Thus it is clear that waste disposal costs are a
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major part of FGC system costs and, further, that any significant savings in waste
disposal costs will substantially reduce total system costs.
A number of the efforts described above, e.g., improving performance of de-
watering equipment, are aimed at reducing disposal costs. Other efforts will be studied
in the near future, e.g., using only the minimum quantity of fly ash required to
chemically treat the FGC waste and marketing the excess.
Another approach to reduce costs is to use disposal methods which avoid the
need for a specially prepared disposal site (e.g., a pond). Two methods currently under
study are disposal in coal mines and at sea.
COAL-MINE DISPOSAL
ARTIFICIAL REEF
CONSTRUCTION
WATER RECYCLE/REUSE
Coal-mine disposal of FGC waste has greatly interested engineers in the FGD
industry for many years because of established means of transportation between the
coal mine and the power plant and because of the need for material to fill the void
left by coal mining. Also, many plants do not have sufficient land area for on-site
disposal. The same reasoning can, of course, be applied to coal ash alone. Preliminary
technical/economic assessments conducted under the EPA Waste and Water Program
indicated that active area surface mines are the most promising candidates for this
disposal approach (20).
FGC waste from the Milton R. Young Station of Minnkota Power Cooperative
near Center, North Dakota, is currently being disposed of in an area surface mine near
the plant. Ash from this plant has been disposed of in the mine for some time. Under
EPA sponsorship, a 2-year assessment of the environmental effects of this operation is
being conducted by the University of North Dakota and the North Dakota State
Geological Survey. The assessment is expected to be completed in late 1979. Successful
demonstration of this disposal approach could make conversion to coal quite feasible
even in areas where land for disposal is limited.
Preliminary costs of mine disposal were also determined. A wide range, from
about $4 to about $10 (in 1977 $) per metric ton of dry solids, depending on treat-
ment, if used, and transportation costs, was reported (20). More detailed costs of this
disposal option are being prepared.
At-sea disposal of FGC waste is also being assessed, because many plants in the
Northeast may have difficulty switching to coal for lack of disposal sites. Many of
these plants, however, do have access to the ocean. It was also recognized that the
major soluble chemical constituents in FGC waste are found in relatively high con-
centrations in seawater. This assessment has identified several potential environmental
problems, the greatest of which is sulfite toxicity. It appears that these problems could
be alleviated either by chemical treatment to a brick-like form or by oxidation to
gypsum. Preliminary costs of this approach were estimated to be about $4 to about $8
[(treated) (in 1977 $)] per metric ton of dry solids for disposal on the Continental
Shelf; deep ocean disposal would be expected to add another $3 to $4 per metric ton
to these costs (20). More detailed costs for this disposal method are being prepared.
Pilot disposal simulation studies are under way to define the environmental effects of
both untreated and treated FGC sludge disposal at sea.
In addition, a large-scale pilot effort is under way to demonstrate the feasibility
of artificial reef construction using treated blocks of FGC waste. This project is being
conducted under the joint sponsorship of EPA, the Electric Power Research Institute
(EPRI), the Department of Energy (DOE), the Power Authority of the State of New
York, and the New York State Energy Research and Development Authority
(NYSERDA). Blocks will be fabricated in. the spring of 1980, then placed in an
approved artificial reef site in the Atlantic Ocean near Long Island. The reef will be
monitored for environmental effects and structural integrity for about 3 years.
With the exception of dry ash handling and disposal, FGC waste operations at
power plants involve the use of vast quantities of water. All operational FGD systems
employ recirculation within the scrubber loop as well as recycling and reuse of clarified
liquor from the waste dewatering system. On the other hand, ash sluice systems are
typically once-through operations; the excess water is either returned to the source
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(e.g., a river) or is evaporated. Because of the scarcity of water in some areas of the
country, environmental limitations on chemical discharges, and the realization that
better water management—including recycle/reuse—can in some cases reduce costs,
water recycle/reuse has become a topic of major interest.
Under the Waste and Water Program, water recycle/reuse efforts which relate
directly to FGC waste disposal have resulted in the following accomplishments:
SUPPORT OF RCRA
REGULATION DEVELOPMENT
EXTRACTION PROCEDURES
• A general methodology was developed for use in a water management plan/design
for the major water use systems in a coal-fired power plant, i.e., the cooling
system, the ash sluicing system, and the FGD system (21). Through the use of
this methodology, all three of these systems can be interconnected, with blow-
down from one system used as feed for another. For example, cooling tower
blowdown might be used for ash sluicing, or ash sluice recycle water might be
used for scrubber makeup.
• A vapor-compression evaporative system (used commercially to treat cooling
tower blowdown) was tested in the treatment of FGC scrubber liquor which
contained very high concentrations of dissolved salts and high total dissolved
solids (TDS) (22). The pilot demonstration test was successful. This type of
system might be necessary in cases where very little freshwater makeup was
required in the FGD system (i.e., for a very tight closed-loop operation) or if the
makeup water quality was unacceptable.
A project was recently initiated to demonstrate, on a pilot scale, closed-loop
(zero-discharge) ash sluicing. The project is cosponsored by EPA's IERL-RTP and
Effluent Guidelines Division in support of development of effluent guidelines under the
Clean Water Act. The principles involved in the general recycle/reuse methodology
already discussed will be used to design the pilot ash sluicing system, which will be
field tested at three coal-fired power plants. Both bottom ash and fly ash will be tested
at each plant. Side-stream treatment of the sluice water will be applied as needed to
prevent corrosion from and/or precipitation of dissolved salts, which will be
increasingly concentrated as the water is recycled. Successful demonstration of this
technology would provide an alternative to dry ash handling.
A study of nonhazardous power plant waste is being conducted by
EPA/IERL-RTP for EPA's Office of Solid Waste to develop quantitative background
information on the coal-fired electric utility industry's solid waste situation. The
study was initiated prior to the determination that some coal ashes and FGD wastes
might fall in the hazardous (now ''special waste") category. Information from the
study will be used by EPA in developing guidance documents to support implementa-
tion of the nonhazardous regulations under RCRA. A draft final report on this effort
is currently under review.
Oak Ridge National Laboratory (ORNL) is conducting a program for EPA's
IERL-RTP and Office of Solid Waste to evaluate the toxicity protocol proposed in the
December 1978 announcement of potential hazardous-waste regulations under RCRA.
This includes use of the extraction procedure, chemical analysis of the extract, and the
biological testing described in the Advance Notice of Proposed Rulemaking (ANPR) of
the announcement (23). Samples of fly ash, bottom ash, and FGD waste have been
tested by ORNL under this program. None of the samples proved to be hazardous by
the definition of the protocol. However, the number of samples tested was inadequate
to establish a trend. The final report on this effort is being prepared.
ORNL has also participated in the American Society of Testing Methods (ASTM)
round-robin series of tests for evaluation of three extraction procedures—the EPA-
proposed method and two alternative methods (Methods A and B) proposed by ASTM.
Several coal ashes and FGD wastes were tested under this project. Only one sample—a
bituminous coal fly ash—failed the toxicity criterion for selenium for all three extrac-
tion procedures. The same sample also failed the criterion for arsenic using the EPA
extraction procedure and ASTM Method B, which is similar to the EPA procedure (i.e.,
an acetic acid leach is used) (24). Testing results from the other laboratories are
currently incomplete.
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STUDY METHODS
CONCLUSIONS
The largest and most significant effort being undertaken in support of the RCRA
regulation development is expected to get under way in the fall of 1979. This 2-year,
multimillion dollar study is being conducted to provide sufficient data and informa-
tion to define the appropriate RCRA standards for storage, treatment, and disposal of
coal ash and FGD waste from coal-fired power plants.
General performance standards under RCRA Section 4004 are expected to be
promulgated in September 1979. Once those standards are promulgated, RCRA Section
1008 guidelines more specific to certain types of disposal practices or certain types of
industry waste may be issued. General performance and design standards under RCRA
Section 3004 were proposed in December 1978 and are expected to be promulgated in
December 1979. The proposed rulemaking for Section 3004 lists coal ash and FGD
waste as "special wastes" (see "Present Regulatory Framework," above). This study
will provide the data necessary to promulgate the guidelines under Section 1008 or the
standards under Section 3004 applicable to utility waste.
In performing the study approximately 16 full-scale waste-disposal sites will be
selected, representing a cross-section of the coal-fired electric utility industry in terms
of (a) types of wastes generated, (b) waste disposal site characteristics (e.g., geology,
hydrogeology, climate), and (c) disposal methods used. Once the sites are selected, a
full-scale evaluation will be conducted of each site, including waste sampling and
analysis; hydrological studies; soil analyses; groundwater and leachate monitoring,
sampling and analysis; and cost analysis. The data will be evaluated and recommenda-
tions will be made regarding the adequacy of the disposal method for meeting the
performance standards contained in the Section 3004 and 4004 regulations. Control
technology alternatives will also be suggested which will provide for compliance with
the Section 3004 and 4004 regulations.
The disposal methods examined in the project will include the most prevalent
methods used in the industry as well as those which are likely to represent the best
control technology standards for disposal of coal ash alone and coal ash/FGD waste
combined. About eight different waste types/disposal methods will be examined.
Each specific disposal operation will be evaluated for its current and potential impact
on the air quality and ground/surface water quality in the vicinity of the disposal site.
The program will include testing each waste for toxicity, using the procedures required
under RCRA Section 3001. In addition, Level I chemical and biological test procedures
established by IERL-RTP for environmental assessment (EA) of energy-related
processes will be used at one coal ash disposal site and one coal ash/ FGD waste
disposal site. Level II EA procedures will be applied to all sites. Physical testing will
also be conducted for potential leachate generation of the waste samples, as well as the
capability for site reclamation. Each site will be evaluated for approximately 12
months. The study is expected to be completed by late 1981. Standards based on the
study results are expected to be proposed sometime in 1982.
A major effort in the Interagency Energy/Environment Program is under way to
characterize solid wastes from power plants and to assess and develop the technology
required to minimize the potential adverse environmental impacts of these wastes. The
program has achieved significant results in a number of areas.
Flue gas cleaning (FGC) wastes have been characterized physically and chemi-
cally; a variety of disposal options have been identified, along with detailed costs
associated with the options. A program of monitoring full-scale commercial disposal
operations is planned. Disposal of these wastes in coal mines is economically attractive
and, therefore, is being investigated through laboratory and field tests. Evaluation of
artificial reef construction using treated blocks of FGC wastes is also under way.
Methods for achieving major cost reductions in FGC waste disposal have also been
identified and are making their way into the process supply market. These include
oxidation to gypsum and improved dewatering equipment. Results of these efforts are
providing a technical data base for regulation of the disposal of power plant wastes.
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References
1. Faber, J.H., National Ash Association. "U.S. Overview of Ash Production and
Utilization." Proceedings: Fourth International Ash Utilization Symposium, St.
Louis, MO, March 24, 25, 1976, MERC/SP-76/4.
2. Laseke, B.A., Jr., PEDCo Environmental, Inc. EPA Utility FGD Survey:
October-November 1978, EPA-600/7-79-022b (NTIS No. PB295650), February
1979.
3. National Ash Association. "Ash at Work," Volume X, No. 4, 1978.
4. Ando, J., Chuo University, Tokyo. "Status of Flue Gas Desulfurization and
Simultaneous Removal of S02 and NOX in Japan." Proceedings: Symposium on
Flue Gas Desulfurization, New Orleans, March 1976, Volume I. EPA-600/
2-76-136a (NTIS No. PB 255-317), May 1976.
5. Bucy, J.I. and J.M. Ransom, Tennessee Valley Authority. "Potential Markets for
Sulfur Dioxide Abatement Products." Proceedings: Symposium on Flue Gas
Desulfurization, Hollywood, FL, November 1977, Volume II, EPA-600/7-78-058b
(NTIS No. PB282091), March 1978.
6. Federal Register, Volume 43, No. 243, pp. 58991 and 58992, December 18,
1978.
7. Leo, P.P. and J. Rossoff, The Aerospace Corporation. Control of Waste and
Water Pollution from Power Plants: Second R&D Report. EPA-600/7-78-224
(NTIS No. PB291396), November 1978.
8. Ray, S.S. and F.G. Parker, Tennessee Valley Authority. Characterization of Ash
from Coal-Fired Power Plants. EPA-600/7-77-010 (NTIS No. PB 265374),
January 1977.
9. Crowe, J.L. and S.K. Seale, Tennessee Valley Authority. Lime/Limestone
Scrubbing Sludge Characterization-Shawnee Test Facility. EPA-600/7-77-123
(NTIS No. PB284111), October 1977.
10. Hargrove, O.W. and G.P. Behrens, Radian Corporation. Results of FGD System
Testing at Louisville Gas & Electric's Paddy's Run Station. Draft report to be
published, prepared under EPA Contract 68-02-2102.
11. Phillips, J.L., et al., Radian Corporation. Development of a Mathematical Basis
for Relating Sludge Properties to FGD-Scrubber Operating Variables. EPA-
600/7-78-072 (NTIS No. PB281582), April 1978.
12. Tarrer, A.R., et al., Auburn University. "Dewatering of Flue Gas Cleaning Waste
by Gravity Settling," presented at the Air Pollution Control Association's 71st
Annual Meeting, Houston, TX, June 1978.
13. Borgwardt, R.H., U.S. Environmental Protection Agency. Sludge Oxidation in
Limestone FGD Scrubbers. EPA-600/7-77-061 (NTIS No. PB268525), June
1977.
14. Head, H.N., et al., Bechtel Corporation. "Results of Lime and Limestone Testing
with Forced Oxidation at the EPA Alkali Scrubbing Test Facility." Proceedings:
Symposium on Flue Gas Desulfurization, Hollywood, FL, November 1977,
Volume I. EPA-600/7-78-058a (NTIS No. PB282090), March 1978.
15. Rossoff, J., et al., The Aerospace Corporation. Disposal of By-Products from
Nonregenerable Flue Gas Desulfurization Systems: Second Progress Report.
EPA-600/7-77-052 (NTIS No. PB271728), May 1977.
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16. Rossoff, J., et al.. The Aerospace Corporation. "Landfill and Ponding Concepts
for FGD Sludge Disposal," presented at the Air Pollution Control Association's
71st Annual Meeting, Houston, TX, June 1978.
17. Rossoff, J., et al., The Aerospace Corporation. Disposal of By-Products from
Nonregenerable Flue Gas Desulfurization Systems: Final Report. EPA-
600/7-79-046 (NTIS No. PB293163), February 1979.
18. Barrier, J.W., et al., Tennessee Valley Authority. Economics of Disposal of
Lime/Limestone Scrubbing Wastes: Untreated and Chemically Treated Wastes.
EPA-600/7-78-023a (NTIS No. PB281391), February 1978.
19. Barrier, J.W., et al., Tennessee Valley Authority. Economics of Disposal of
Lime/Limestone Scrubbing Wastes: Sludge/Fly Ash Blending and Gypsum
Systems. EPA-600/7-79-069 (NTIS No. PB297946), February 1979.
20. Lunt, R.R., et al., Arthur D. Little, Inc. An Evaluation of the Disposal of Flue
Gas Desulfurization Wastes in Mines and the Ocean: Initial Assessment. EPA-
600/7-77-051 (NTIS No. PB269270), May 1977.
21. Noblett, J.G. and P.G. Christman, Radian Corporation. Water Recycle/Reuse
Alternatives in Coal-Fired Steam-Electric Power Plants: Volume I. Plant Studies
and General Implementation Plans. EPA-600/7-78-055a (NTIS No. PB282211),
March 1978.
22. Weimer, L.D., Resources Conservation Company. Effective Control of Secondary
Water Pollution from Flue Gas Desulfurization Systems. EPA-600/7-77-106
(NTIS No. PB 278373), September 1977.
23. Federal Register, Volume 43, No. 243, pp. 58955-58967, December 18, 1978.
24. Personal Communication, J.L. Epler, Oak Ridge National Laboratory, May 1979.
130
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ARTIFICIAL FISHING REEF CONSTRUCTION
USING COAL WASTES
(film)
AT-SEA DISPOSAL
PROJECT
STABILITY AND
LEACHING
To cut imports of foreign oil, power plants are increasingly converting to coal
use, thus exacerbating the already-acute problem of disposal of coal wastes. Flue-gas
scrubbers remove fly ash and SOX, producing flue-gas cleaning (FGC) wastes equal to
30 percent or more of the volume of coal burned, the percentage being a function of
the amount of sulfur the coal contains. A large plant may burn 7,000 tons of coal a
day, and it is estimated that by the year 2000 the nation's coal-burning power plants
will produce over 100 million tons of FGC waste per year.
The northeastern United States, where land is scarce and costly, will not support
the large landfills needed to accommodate the thousands of tons of sludge and fly ash
produced daily. Many plants in this area, however, have access to the ocean, and
assessments are being made of various methods of at-sea disposal of FGC waste. This
assessment is a project of the Marine Science Research Center of the State University
of New York at Stony Brook, cosponsored by the New York State Energy Research
and Development Authority, the U.S. Environmental Protection Agency, the U.S.
Department of Energy, the Power Authority of the State of New York, and the
Electric Power Research Institute. The project is a large-scale pilot effort to demon-
strate the feasibility of artificial fishing reef construction using treated blocks of FGC
waste.
In the early stages of this project, stabilized blocks of coal waste were
laboratory-tested at Stony Brook. They were then submerged for 19 months as a small
artificial reef in Conscience Bay in Long Island Sound off Port Jefferson, New York.
The stability and leaching properties of the blocks in the sea water were of primary
concern. Data were also collected on the type and amount of marine plant life growing
on the blocks, and possible toxic effects on marine life. These preliminary investi-
gations were very encouraging; the submerged blocks did not disintegrate, leaching of
trace metals appeared to be minimal and harmless, and the plant life they attracted
was uncontaminated by chemicals.
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CONSTRUCTION
PROJECT SITE STUDIES
TEST BLOCKS ANALYZED
The next phase of the project involves the construction of an artificial reef in
an approved site in the Atlantic Ocean off Saltaire, Fire Island. This large reef will
consist of approximately 700 coal-waste blocks, each 1 yard square and weighing 1
ton. The blocks will be fabricated in the spring of 1980 and, after emplacement late
that summer, will be monitored for environmental effects and structural integrity
for about 3 years. Once the engineering aspects of production and transportation
of the blocks are developed, a cost analysis will be done to determine the economic
feasibility of this method.
Oceanographic studies will define the environment of the project site before
the reef is laid down. These studies will determine the physical and chemical properties
of the water, including temperature, salinity, dissolved oxygen, suspended sediment,
nutrients, and heavy metals. Samples of the phytoplankton and zooplankton
communities will be taken, and divers will make surveys of both the project site and
an existing artificial reef nearby. Laboratory studies of the chemical composition of
the blocks and of their leaching properties will continue during this phase of the
project.
Once the reef is in place, biological colonization of the surfaces of the blocks
will be measured monthly. Test blocks retrieved from the reef will be analyzed to
determine what sorts of organisms grow there. The materials of a fishing reef must
attract the kinds of marine life that will in turn attract a variety of fish species.
Control experiments at the reef site will be used as a basis for comparing the
performance of the coal-waste blocks with that of other submerged objects, such as
ship hulls, which are already known to attract plant life that attracts fish.
If the use of stabilized coal-waste blocks as artificial reefs proves environmentally
and economically sound, the project will have demonstrated both an attractive
alternative to landfill disposal of coal wastes and a means to increase the fish
population in an area, and will have overcome a major obstacle to burning coal in
power-generating plants and industries.
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J
BP
133
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U.S. DEPARTMENT OF ENERGY
FLUIDIZED-BED COMBUSTION PROGRAM
Steven I. Freedman, Ph.D.
William T. Harvey
Division of Fossil Fuel Utilization
U.S. Department of Energy
The fluidized-bed combustion (FBC) of coal is a highly efficient process that uses
a mixed bed of limestone, lime, sulfated lime, and ash. Figure 1 is a schematic drawing
of the process. This process uses crushed coal (1/4" x 0) which is fed into a fluidized
William T Harvey
EXHAUST
SECONDARY CYCLONE
PRIMARY CYCLONE
FREEBOARD <-
HEAT REMOVAL
WATER WALLS
IN-BED
HEAT REMOVAL
ASH
~^SULFATE & ASH
DISTRIBUTOR PLATE
AIR
LIMESTONE
COAL
AIR FLOW: 2 15 ft sec
PRESSURE:
TEMPERATURE: 1500°F-1600UF COAL SIZE:
SULFUR REMOVAL: CaO + S02 + 112(02)
FIGURE "[-Typical fluidized-bed combustor
1 - 25 atm
114 in. x 0
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FBC FEATURES
ECONOMICS
COST ADVANTAGE
bed of limestone or dolomite where combustion takes place. The coal and limestone
are held in suspension by the injection of air through a distributor plate in the bottom
of the combustion chamber. The limestone, in the form of calcium carbonate, is
calcined to form calcium oxide which reacts with the SO2 released during the combus-
tion of coal. The result is a solid waste along with the coal ash. Fluidized-bed combus-
tion, which takes place at a temperature between 1500°F and 1600 F, has several
potential advantages.
This temperature range permits
• limestone to calcine,
• lime to sulfate,
• enhanced heat transfer rates, and
• generation of utility grade superheated steam,
while avoiding
• thermal NOX generation,
• severe material problems,
• ash agglomeration and clinker formation, and
• slagging and fouling.
The FBC process can be designed to occur either at atmospheric pressure or at
elevated pressure. The atmospheric pressure process, referred to as AFBC, is the least
complicated. Combustion at elevated pressures must be coupled to an expansion
turbine to recover mechanical energy for combustion air compression and to generate
power from the hot pressurized products of combustion. This process is referred to as
pressurized fluidized-bed combustion (PFBC). PFBC inherently produces less NOX and
is capable of removal of sulfur oxides to a greater extent than AFBC. The exact
mechanisms of this process that result in these environmental advantages are not
fully understood, but the data are conclusive. Several process configurations for AFBC
and PFBC are being pursued by different organizations within the overall program
strategy.
Many economic studies have been performed on FBC, but no commercial plant
has been built and operated to provide actual cost data. Design studies show that
when comparisons are made with alternative technologies, certain general conclusions
can be made:
• Coal-fired power plants are much more expensive than oil- or gas-fired power
plants.
• AFBC boiler pressure parts and the combustion chamber have the potential for
being less expensive than those components in pulverized coal-fired steam
generators.
• Elimination of a scrubber in a FBC power plant is a major cost saving, assuming
a scrubber is required to meet emission regulations in a conventional plant.
« Equipment for handling sorbent and spent bed will add approximately one-half
of the cost of the scrubber to the FBC power plant.
• Cost of a pulverizer is saved, but fan costs are substantially increased.
• AFBC systems which require dryers have this added cost and, if sized coal is
required, this will result in increased operating cost.
Cost studies comparing utility AFBC steam generators with pulverized-coal-fired
steam generators equipped with stack gas scrubbers show a definite cost advantage for
the AFBC units. In the industrial area, AFBC boilers are competitive today with
conventional boilers with scrubbers. The major economic advantage of AFBC boilers
is in their ability to burn a wide variety of coals and industrial wastes. This broadening
of the fuel resource base for a particular plant, as well as the nation, will result in
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DOE PROGRAM STRATEGY
lower fuel cost. PFBC power plants have an additional economic advantage. A PFBC
plant will cost about as much as an AFBC plant, but its efficiency for power genera-
tion will be higher, 39% versus 35% for an AFBC plant. This results in a 10% fuel
savings, which is substantial. The degree of hot gas cleanup required for a PFBC
plant and the design of this equipment will materially influence the economics.
The overview of FBC strategy is to have a continuing staged technology
development program to provide research data and an understanding of the
phenomena, to test alternative process configurations, and to obtain experience with
components and provide an engineering foundation for the technology. The staged
technology program is a series of developmental and prototype units which will be
scaled up to successively larger units for the purpose of engineering development and
then to commercial prototype testing. The units will increase in size as development
takes place from process development units (PDU's), to pilot plants, to industrial
demonstration units and then to utility demonstration units. Units will become less
flexible and closer to commercial systems as development progresses to larger sizes.
The various elements of research and development program strategy are shown in
Table 1.
TABLE 1
Overview of FBC strategy
• From applied research and exploratory development, estimate cost, performance, and
scale-up factors to determine key technology development required for conceptual
designs of commercial scale plants.
• Design, construct, and operate PDU's for technology development to determine design
performance parameters for fluidized-bed-combustors, gas cleanup and turbine
modifications.
• Design, construct, and operate pilot plants to obtain engineering data on processes,
plant integration, and operability.
• Design, construct, and operate engineering demonstration plants to develop and prove
full scale equipment in late 1980'sfor commercialization in the 1990's.
• Develop improved components and equipment to adapt demonstrated processes to other
commercial systems.
INVOLVING INDUSTRY
Part of the overall strategy is to avoid an intermediate technology transfer by
involving industry in the program, on a working basis, at the earliest opportunity.
Thus, existing commercial, industrial, and utility users and equipment suppliers are
closely involved in the DOE FBC program. The approach to implementing the strategy
is as follows:
• Develop and refine the technology and engineering data for high risk elements
for which federal funds are required.
• Design, construct, and operate technology development facilities with federal
funds. However, provide and arrange for operation by industry to further define
and refine the technology/engineering data base and to test various
concepts/components.
• Design, construct, and operate engineering development systems. These systems
would be provided by industrial suppliers at industrial and utility sites on a cost
share basis.
• Obtain multiple qualified manufacturers to develop alternate approaches to
minimize risk. This will ensure that future competition will exist and provide a
broad manufacturing and engineering base for commercial implementation.
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BOILER MARKET
IMPEDIMENTS
Development of FBC is progressing rapidly, and it seems probable that the first
commercial contracts will be signed during 1979-most likely for small industrial units.
Orders for utility FBC units cannot be foreseen clearly at present, but it seems
probable that there will be none before 1987.
AFBC boilers in the size range of 1/2 to 2 MWe equivalent have been operated at
a high level of reliability. They could be suitable for space heating purposes. It is
expected that industry will extend this product type to a size range of 2 to 10 MWe
equivalent. The DOE has funded several projects for demonstrating industrial units for
institution and commercial space heating using bituminous and anthracite coal. For
industrial process service, AFBC boilers of 10 to 50 MWe equivalent will require
high reliability before buyers will purchase these boilers. Buyers need to be assured of
continued operation so that the remainder of their industrial process is not
compromised by lack of steam continuity.
A commercialization study task force, one of several commissioned by the
Undersecretary, examined the AFBC industrial boiler product and market. This study
concluded that the large industrial AFBC boiler was ready for commercialization. It
also found that a market existed which held adequate promise for substantial
additional coal use within the next decade. Industry acceptance of AFBC boilers will
require resolution of the following uncertainties:
• Adequate technical and environmental performance.
• Operating reliability and system maintainability.
• Dependable basis for cost.
A Program Opportunities Notice (PON) was issued to obtain industrial AFBC boiler
units to meet the above requirements. The results of the program that should result
from this PON would complete the development of AFBC for industrial, institutional,
and commercial applications. The continued development of a technology data base
built on a development program will be needed until these systems are mature and
adequate industrial laboratories are operational to supply industry's needs.
Commercialization of FBC has major environmental and socioeconomic impedi-
ments to overcome. Some of the problems are common to all coal utilization tech-
nologies. Briefly, they are as follows:
Environmental Impediments
• Solid waste disposal
• Uncertain future standards for SO2, NOX, and particulates
• Possibility of new regulations, fine particulates among others
• Heat rejection
Socioeconomic Impediments
• Plant siting delays and costs
• Coal mining, coal transport and distribution
Either AFBC or PFBC can be used in utility and very large (over 50 MWe equiva-
lent) industrial applications. AFBC utility systems can make use of the AFBC indus-
trial technology as a data base. The question arises as to which is the most appropriate
technology for utility services. There are at least three options:
• Conventional AFBC
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HIGH RISK
LOW RISK
PROCESS OPTIMIZATION
• Advanced AFBC, such as the staged fluidized-bed combustion, fast fluidized-bed,
or other systems of advanced design
• PFBC
An AFBC development program will require at least six (6) years before even the
smallest utility scale plant could be demonstrated.
Three levels of risk for PFBC technology are based on the inlet temperature of
the gas turbine with the higher temperatures offering the advantage of higher system
efficiency.
• High temperature/high risk
• Medium temperature/medium risk
• Low temperature/low risk
The original PFBC concepts of the early 1970's were those based on gas turbines
operating at 1650°F blade temperature (based on clean fuel) with PFBC combustors.
This PFBC temperature favors high combustion efficiency and high SC>2 removal. This
is a high risk approach because of potential problems with fouling, erosion and corro-
sion; and a development program of substantial magnitude and time could be required.
An intermediate approach to PFBC/gas turbine arrangements is being pursued by
a consortium headed by American Electric Power Company (AEP). AEP's proposed
plant would include a gas turbine originally designed for use with crude and residual
oil and designed for a turbine inlet temperature of 1470 F. The system will be
designed with the capability of lowering turbine inlet temperature to 1000°F-1100°F
by use of an air by-pass from the compressor discharge to the turbine inlet.
Power recovery turbines operating at an inlet temperature of about 1000°F have
been used extensively with regenerator off-gas from catalytic cracking operations. Such
turbines could be used in PFBC cycles in combination with heat recovery units suitable
for reducing PFBC gas temperature from 1600°F to 1100°F. Power recovery turbines
are available commercially, and they operate at a lower pressure (3.0 atm vs. 12 atm)
and at a lower gas velocity (1000 fps vs. 1500 fps). Paniculate loadings are typical of
the efflux from a PFBC combustor, and the effluent size distribution is not unlike that
of PFBC. However, cat cracker gases do not contain the alkalis or alkali sulfates or a
variety of ash mineral matter (such as quartz and ferrosilicates) found in coal combus-
tion products. At temperatures below 1150°F, the corrosive effects of alkalis are
believed to cause damage at a substantially reduced rate, permitting over 25,000 hours
of service. The fouling (deposition) tendency of coal ash in such machines is not
known, but conventional techniques for removing deposits from gas turbines in PFBC
systems are expected to be adequate. The power recovery turbine (turbo-expander) is a
rugged machine and, combined with the less severe operating conditions, is an approach
that offers substantially reduced technical risk. The low temperature approach would
provide a turbocharged boiler that would be compact, potentially lower in cost, and
environmentally cleaner than alternative combustion systems.
The major factors affecting the technical and cost performance of FBC systems
are combustion efficiency, sorbent performance, materials durability, and equipment
size and complexity. All of the foregoing are highly dependent on design and operating
variables including coal and sorbent type, operating temperature, and fluidizing
velocity.
Much information exists on the relationships among operating variables and
performance, but the FBC process has not been optimized. Improvement of the
competitive advantage of FBC will require continuing R&D support, particularly if
technology implementation is to proceed from small industrial applications to large
industrial and utility applications. Obviously, as unit capacity increases, costs become
increasingly important so process optimization continues to be an important element
of the RD&D program. For example, combustion efficiency (carbon utilization) in
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GENERATOR SIZE
PROCESS OPTIMIZATION
AFBC depends on a host of factors, the most important of which is fluidizing velocity.
Fluidizing velocity establishes the amount of carbon elutriated from the bed and the
need for its recovery and further combustion; in addition, fluidizing velocity is directly
proportional to bed size (area). At higher velocities of 8-12 ft/sec, 10-15% of the coal
carbon is elutriated from the bed and must be recovered and returned for additional
burning in a separate cell (carbon burnup cell). At lower velocities of 3-5 ft/sec, a
carbon burnup cell is not required. Higher velocities would be preferred because they
permit more compact steam generators and the shop fabrication of units with greater
capacity. Capacities of shop fabricated units are expected to be 300,000 Ib/hr of steam
for high velocity systems; at low velocity, unit capacity of shop fabricated boilers
likely could not exceed 150,000 Ib/hr.
Figure 2 shows the relative size of three steam generators of 550,000 Ib/hr
capacity designed for various fuels. As can be seen, the coal-fired AFBC unit is similar
in size to an oil-fired unit. The AFBC unit is smaller than a conventional coal-fired
unit because of the AFBC's higher volumetric heat release rate, typically 100,000
Btu/hr-ft3 as compared with 20,000 Btu/hr-ft3. Even at the lower velocities, the AFBC
unit still would be significantly smaller than the conventional coal-fired unit.
Another area of importance in AFBC technology is fuel distribution within the
bed. Fuel distribution and bed mixing greatly influence carbon utilization and the
behavior of heat exchangers immersed in the bed. In the latter case, fuel distribution
must be even to avoid localized oxidizing and reducing zones which could cause severe
materials problems. Up to the present time, the fuel distribution problem has been
solved by introducing small quantities of fuel per unit area of bed, and it has been
found necessary to provide a feeder for every 10 ft2 of bed area. This requires many
fuel feeders or splitters for distribution. The large number of fuel feeding points and
the. complexity of the feed system are areas that represent an opportunity for process
equipment inprovements. Development work is being performed to simplify the feed
system using a spreader-stoker feeder which throws the coal onto the surface of the
bed. This approach, shown in Figure 3, is to be tested in the industrial steam generator
at Georgetown University. The steam generator is shown in Figure 4.
Fuel feeding/distribution and fluidizing velocity also are important with regard to
environmental performance. Thus, after considering the complexity of the many
process and design interrelationships, it is apparent that process optimization is
required if AFBC technology is to become technically and cost attractive in larger size
applications. In addition, the bed profiles of individual species must be known together
with their creation/destruction mechanisms in order to have a basis for emission
standards. The possibility of staged FBC exists with reduction of NOX as a goal. Coal
o
o
COAL
(FLUIDIZED BED)
OIL
COAL
FIGURE 2-Comparison of 550,000 Ib/hr units
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COAL IN
STOKER
FEEDER
o
o
FLUIDIZED BED
T T AIR T
FIGURE 3—Conceptual arrangement of overfeed FBC
FLL!L
GAS
OUTLET
MUD
DRUM
DOWNCOMER
FLUIDIZED BED STEAM GENERATOR
STEAM OUTLET GEORGETOWN UNIVERSITY
100,000 LBS./HR. 675 PSIG. DESIGN PRESSURE
SATURATED STEAM
SPREADER
COAL FEEDERS
(TYP)
FLY ASH
REINJECTOR
LIMESTONE
FEED PIPE
DOWNCOMER
AIR INLET _
BED MAT'L
DRAIN (TYP)
FIGURE ^-Industrial fluidized-bed steam generator, Georgetown University
AIR DISTRIBUTION
GRID LEVEL
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LOW-TEMPERATURE
APPROACH
HIGH-TEMPERATURE
APPROACH
feed, ash removal, and flyash recycle systems need to be brought to the point of
practical operation. Baghouse or precipitators must be engineered for the high calcium
flyash.
In PFBC, fluidizing velocity and fuel distribution are not as important as in
AFBC-pressurization dramatically reduces the size of the combustor. The area of
greater uncertainty is the gas cleanup necessary for acceptable gas turbine life.
The technical risk associated with gas turbines in PFBC cycles is a function of
turbine inlet temperature. The PFBC cycle is flexible in regard to the operating
temperature of the gas turbine which is related to turbine durability/operability. At
a turbine inlet temperature of 1600°F, the highest now anticipated for PFBC, it is
expected that cycle efficiencies of 41% or greater can be achieved. Operation at this
temperature level also involves higher technical risk with the gas turbine. In low-
temperature (1100°F) cycles, technical risk is minimized, and cycle efficiency still
is a respectable 34-35%. At the intermediate turbine temperature of 1475°F proposed
by AEP, commercial operation is predicted to give an overall plant efficiency of 39.4%.
The high-temperature, high-risk approach represents a potential improvement of
6 or 7% in cycle efficiency compared with the conservative, low-temperature approach.
Thus, there is substantial incentive to develop the technology to the stage that the
higher temperature turbines can be utilized. Attainment of this goal would result in
substantial fuel savings in PFBC plants, equivalent to a reduction in heat rate from
about 10,000 Btu/kWh. Achieving this goal, however, will depend on future develop-
ments in technology related to gas turbines and gas cleanup. Some of the R&D options
being pursued or considered for these components include:
• Improved resistance of turbine materials to corrosion by
— blade cladding materials
— blade cooling
• Advantages of larger scale turbines (and blades) with respect to blade erosion.
Larger blades are expected to experience less erosion because their larger turning
radii will cause less deflection of particles from the flow streamlines.
• Removal of turbine deposits by use of cleaning materials of controlled abrasivity
• High-efficiency particulate collectors of the centrifugal and mechanical filtering
types'
• Removal of corrosive alkali metal vapors from the gas by chemical "getters''
such as diatomaceous earth and activated bauxite
DOE'S RD&D PROGRAM
The current AFBC and PFBC programs consist of several projects for technology
development and for engineering demonstration while some are planned for commercial
demonstration. The programs initially involve technology development by investigations
in successively larger units followed by engineering and commercial demonstration. The
AFBC program includes several projects, listed in Table 2, to develop the technology
base needed for both utility and industrial applications. These projects include the
process demonstration unit at Alexandria, Virginia, for exploratory development; the
Component Test and Integration Unit at Morgantown, West Virginia, for technology
optimization and component development; and the 30 MWe pilot plant at Rivesville,
West Virginia, for engineering development.
DOE efforts in AFBC industrial applications draw on the experience of the
industrial participants and are a natural outgrowth of the technology development
program. The industrial applications projects include unit sizes up to 100,000 Ib/hr
equivalent steam generating rates and are listed as follows:
• Conventional AFBC
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— Georgetown University Boiler for Saturated Steam
- Great Lakes Naval Training Center Boiler for Superheated Steam
— FluiDyne Process Air Heater
— Exxon Process Heater for Crude Heating
— Anthracite Applications Projects
• Oak Ridge National Laboratory Coal Combustor for Cogeneration
• Advanced Concepts
- Battelle Fast Fluidized-Bed Boiler
— Wormser Staged Fluidized-Bed Combustor
AFBC INDUSTRIAL
APPLICATION
Demonstration of conventional AFBC in industrial application will be achieved
by 1983. This engineering demonstration is certain to precede that of advanced con-
cepts. Boiler suppliers participating in the program are expected to proceed with
commercialization of the demonstrated technologies. Demonstration projects will be
undertaken to accelerate widespread commercialization of large industrial units and are
expected to confirm the economics of AFBC by late 198G"s.
AFBC UTILITY
APPLICATION
Commercialization of AFBC for utility applications is expected to follow com-
mercialization in the industrial sector because of the scale which is involved. The
30 MWe pilot plant shown in Table 2 will confirm the process design, while the 6 MWe
CTIU will provide information for process optimization and component development
and testing. The coal feed test apparatus and boiler material test apparatus projects are
anticipated to provide the necessary input to design engineering demonstration units
for AFBC utility applications. The Tennessee Valley Authority is likely to undertake
TABLE 2
AFBC projects and functions
Project
Function
Bench/PDU
Provide data for technology base and design data for
larger units.
6MWeCTIU
Further broaden technology/engineering base, test
components, optimize system configuration for stacked
cells, investigate dynamic behavior, provide "hands-on"
access to private sector.
30 MWe Pilot
Plant
Evaluation of large beds for performance regarding com=
bustion efficiency and pollution control.
Utility Demonstration
Plant
Demonstrate FBC technology in utility environment on
a large scale unit.
Coal Combustion for
Cogeneration
Demonstrate feasibility of externally-fired heater for
closed cycle or externally fired gas turbines for total
energy systems.
Industrial
Demonstration
Plants
Develop wide base of AFBC designs for industrial/
institutional applications covering boilers, steam generators,
process heaters.
Anthracite
Culm
Application
Initiate FBC program for culm and anthracite and coal
refuse utilization with industry participation.
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FBC WASTES
the AFBC engineering demonstration unit. By the early 1990's, TVA should have this
project completed and it likely will be followed by a commercial utility project.
The technology and engineering development projects for the PFBC program
are listed in Table 3. The major projects include the Curtiss-Wright (C-W) small gas
turbine (SGT) for technology development, the C-W/pilot plant and the lEA/Flexible
Test Facility for engineering development using current state-of-the-art gas turbines.
Although substantial quantities of waste from FBC processes are not predicted
for nearly a decade, the AFBC and PFBC processes will be attractive to potential users
only if acceptable waste disposal or utilization methods are developed. Therefore,
commercial implementation of FBC must be preceded by meaningful studies on waste
disposal and/or utilization. The latter activity is important since few industrial facilities
located in urban areas have the means to dispose of FBC wastes. At best, the FBC
process would be enhanced if solid wastes could be used as a raw material, providing
revenue to the FBC user; at the least, the waste must be removed from the FBC site at
reasonable cost and disposed of in an environmentally acceptable manner. So, solid
waste research is being conducted concurrent with other FBC technical activities to
investigate thoroughly the utilization of FBC waste products in agricultural and other
applications.
TABLE 3
PFBC projects and functions
Project
Function
Bench/PDU*
Provide data for technology base and design data for large
units.
13 MWe Pilot
Plant
IEA PFBC Facility
Design, construct, operate, and evaluate PFBC air heater
cycle for scale-up to utility size.
Perform research on coal combustion, heat transfer, SC^
sorption and fluidization characteristics. Gas volume
matched to 10 MWe gas turbine. Clean-up requirements
for gas turbine not yet determined.
Cycle Development
Develop/evaluate alternative PFBC cycles for commercial
implementation.
Engineering Demon-
stration System
Verify PFBC concept, verify design data, and generate
commercialization data.
* Includes Exxon Miniplant, CPC Granular Bed Filter, Curtiss-Wright SGT/PFB Unit,
and CURL/Leatherhead Research Facility.
-------
panel
discussion
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CONTROL TECHNOLOGY PANEL DISCUSSION
WITH QUESTIONS AND ANSWERS
Frank T. Princiotta
Energy Processes Division
U.S. Environmental Protection Agency
Michael Shapiro
Division of Fossil Fuel Utilization
Department of Energy
H. William Elder
Emission Control Development Projects
Tennessee Valley Authority
B. G. McKinney, Ph.D.
Fossil Fuel Power Plants Department
Electric Power Research Institute
1
Michael Shapiro
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Benjamin Linsky, P.E.
West Virginia University
Leon Green, Jr.
General Atomic Company
John A. L. Campbell
Peabody Coal Company
Torghy Schutt
Commission of Energy Research & Development
Stockholm, Sweden
MR. PRINCIOTTA: The recently promulgated utility New Source Performance
Standard (NSPS) calls for 70 to 90 percent sulfur oxide control, with a minimum
of 1.2 pounds per million BTU from fossil fuel-fired power plants. It calls for 0.03
pound per million BTU particulate standard and a slightly more stringent nitrogen
oxide standard of 0.5 to 0.6 pound per million BTU as opposed to the current 0.7
pound. This is perhaps the most important standard relating to coal combustion ever
set. The first question before this panel this morning involves the implications of the
new standard with regard to commercial selection of control technology and as regards
research, development, and demonstration needs and goals.
MR. SHAPIRO: The regulations will have a definite impact on coal use. They are
certainly more severe than the current ones, but they will also allow for selection of
control technology. No particular solution or technology will be applicable for all
situations. The technology will be very much a function of the particular site; the
geographical location; the state regulations, which may be more stringent than Federal
regulations; the availability of various coal supplies; and the sulfur content of the coal.
In each application, utilities will have to find the optimum solution to their control
problems, be it, for example, the use of coal preparation, the continuation of lime-
stone systems, or the use of dry scrubbing approaches, which show so much promise
now. It is very important that for each situation a choice, based on a particular loca-
tion and on economics, be available to the utilities.
MR. ELDER: It is fortunate that the ceiling was set at a level that keeps most of the
coal that is available for utilities and other uses in the picture for continuing energy
production. The break point on the regulation is reasonable in that it allows the use of
low sulfur coals with degrees of removal efficiency that are reasonable for this new dry
scrubbing technology. The combination of coal preparation and coal cleaning with dry
scrubbing could be quite important for utilization of the mid-range sulfur coal. So,
in effect, the new regulations have not closed out the options. With one exception,
they keep all of them open. The very high sulfur coals will require more than 90
percent removal efficiency. This will require something other than the lime and lime-
stone scrubbing technology that is now the leading method.
As to the reasonableness of the removal efficiencies, we know that the 90 per-
cent level established is certainly achievable, at least on an instantaneous basis. The
main question becomes, how long can we continue to meet 90 percent removal during
prolonged operation? It is a risk factor. We trade off removal efficiency versus
reliability. To maintain 90 percent, particularly over an extended averaging period, will
require fairly close control of the operating characteristics of the scrubber. Matching
up the rate of addition of absorbent with the SC>2 concentration in the flue gas will be
quite important in meeting the level. In the utility industry, particularly in the appli-
cation of the technology at this stage, the control of the ratio between absorbent and
SC>2 has not been as good as it will need to be to get 90 percent on a reliable basis.
DR. MCKINIMEY: As far as a commercial venture is concerned, in the near term,
probably until 1987, lime and limestone scrubbing are what is available. We are there-
fore going to produce sludge for several more years. Some of EPRI's funds are going
into developing advanced regenerable systems or systems that make gypsum, but at this
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time, for the utility industry we represent and that funds us, the near-term option is
lime and limestone. This is not necessarily the most beneficial option, and therefore a
lot of our money is going into other R&D projects. There will certainly be some room
for choice in the future, but right now a utility is unlikely to opt for any process but
lime or limestone; the other technologies are just not sufficiently developed.
QUESTION: The old utility boiler systems used multiple retard underfeed stokers and
multiple boilers so that they would have redundancy. With similar built-in redundancy,
would there be such concern about maintaining the 90 percent SO2 removal relia-
bility?
RESPONSE (Mr. Elder): The 90 percent was removal efficiency rather than reliability.
Since the trend is toward greater redundancy, more spared equipment, the reliability is
improving. The question is one of cost. The degree of cost must be considered; the sky
is not necessarily the limit. Perhaps we neglected to address the R&D needs. When we
spoke earlier of forced oxidation, the point was not stressed that the conversion
provides gypsum that can be recirculated back to the scrubbing system. That is a key
process step that improves the operating characteristics and reduces the scaling and
puddling potential. One of the significant factors in the Japanese success is that they
use forced oxidation and recycle the gypsum seed back to the scrubber. This is the
direction in which the EPA program is heading, and it is the right direction, as is
DOE's attempt to accelerate development of forced oxidation work. It will be very
important for the future of lime and limestone scrubbing.
Another important area that needs improvement is instrumentation, the
measuring devices used on scrubbing systems, not only to measure gas concentra-
tions but to measure gas flow rates, slurry flow rates, and pH so that we can have
better control of the process chemistry.
The last area that needs work is mechanical components. Provided we have
proper controls, we no longer worry much about process parameters. The real
problems with reliability, with keeping systems in operation, are with mechanical com-
ponents. In our R&D program we have not done a good enough job of selecting the
best equipment components, particularly in areas of control gas and liquid flow, so
that we can make recommendations to equipment suppliers that would give us more
reliable systems. Additional work is needed in this area.
RESPONSE (Dr. McKinney): Particulates evoke similar concerns. Depending on how
the environmental control agencies monitor the particulate standard, the utility
industry, in order to meet the standard on a continuous basis, is probably entering a
new era in regard to electrostatic precipitators. We do not know well the performance
and reliability of precipitators. Since we have never had the continuous particulate
monitors, we are looking at something new.
Because we try to do things on an economic basis, we have had some studies
done that indicate that baghouses are possibly the most economical particulate control
devices. We do not have experience with baghouses on large pulverized coal for boilers.
We certainly do not have experience on high sulfur coals. From the Arlington station
in Texas there is some minimum experience on lignite or low sulfur coal. Because
we do not have the requisite experience, we have to caveat the economics of the
baghouse situation with the precipitator.
MR. PRINCIOTTA: This conference, and in particular this session, has thus far focused
primarily on conventional combustion, pulverized coal, combustion of coal, utilizing
combustion modification for NOX control and flue gas cleanup, particulate and sulfur
oxide control. The exception was the fluidized bed presentation. What do the panelists
think about the viability and commercial status of emerging coal to electric tech-
nologies, such as fluidized bed combustion, low BTU gasification, coal liquids, and
possibly even some of the softer noncoal technologies?
MR. SHAPIRO: The advanced technologies will not affect the utility and industrial
sectors to any great extent until the 1990's at the earliest. The one exception to that
might be the industrial applications for atmospheric fluidized bed combustion, which
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seems to be moving rapidly toward viability now, with the possibility of commerciali-
zation in the early 1980's. Advanced technologies, such as pressurized fluidized bed
combustion, combined cycle systems, low BTU gasifiers, MHD, and carbonate fuel
cells, deal with the problems associated with meeting environmental regulations that
will be enforced at a later time. They also focus on improved efficiency, which will
result in lower total emissions and lower costs for electricity. It is too early to say that
there are clear winners among the advanced technologies, so we are taking parallel
paths in developing them, looking at them as alternative energy sources that will
impact the marketplace sometime in the 1990's.
MR. ELDER: From a utility viewpoint, there is now no alternative to conventional
combustion with flue gas desulfurization. The most cost-effective way to meet both
the proposed New Source Performance Standard and the existing standards is by use of
conventional technology. The nearest-term challenge will be with fluidized bed
combustion because it is further developed. TVA is in the midst of a design phase
for a 200-megawatt atmospheric fluidized bed demonstration that promises to be
an economic and technical competitor to conventional technology. Beyond that, I see
nothing on the horizon that can help the economics or the environmental considera-
tions for the utility industry. There are a couple of sidelines that may be important,
such as liquid fuel or refined coal. There could be an alternative for use of distillate oil
in gas turbines, used primarily for peaking power. As a higher proportion of the
demand shifts toward nuclear, there will be more need for short-term peaking power,
and gas turbines are likely to serve that need. An alternative to distillate oil for gas
turbines is a real need in the utility industry.
DR. MCKINNEY: Based on economic evaluations of technologies by the Electric
Power Research Institute, the conventional coal-fired system, which we know the
cost of because we have built some, is running about 50 mills per kilowatt hour
instead of 35. Pressurised fluidized bed combustion, atmospheric fluidized bed com-
bustion, and coal gasification with a combined cycle system, all involve about the
same generating costs, 50 to 60 mills per kilowatt hour.
We have recently started another economic evaluation of the advanced conven-
tional system. There is probably still a lot of R&D to do on the advanced conventional
system, and we probably have a better handle on the costs of the conventional system.
We are trying to get some optimistic data on the costs of the conventional system
to compare with estimates for the emerging technologies, with an end in mind of
possibly advancing the state-of-the-art in the conventional pulverized coal-fired boiler as
another emerging technology. We have also done some evaluation of solvent refined
coal. So far, our projections on the generating capacity in this country are incon-
clusive.
MR. SHAPIRO: Although my area of expertise is not the softer technologies, the
projection for them is that they will be viable only when they are economically
competitive, which ties in closely with local situations. If people can get a return on
their investment in the use of solar, insulation, or conservation measures for a
particular application, they will pursue it. The Government has made it easier through
tax rebates and tax credits. The so-called soft technologies are not the total answer,
certainly not for electrical generation in the near term. If, for heating applications such
as hot water, these technologies become economically worth people's investment, they
will definitely make a contribution; anything saved through solar use or conservation
diminishes the requirements for oil- and coal-fired electric generation.
MR. ELDER: The soft technologies are a supplement to, not a replacement for,
conventional power, specifically electric power, even though TVA has quite an aggres-
sive loan program encouraging conservation through insulation. They give financial
assistance to people to install solar demonstrations as test units in their homes,
particularly for water heating. There are certainly supplementary technologies that will
eventually contribute, although probably in a minor way, to saving energy for
additional production of electricity. Every little bit helps, and we have to be more
conscientious about looking at every piece of the puzzle, so that eventually we can put
it together to advance everyone's interests, including those of us in the power-
producing business.
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DR. MCKINNEY: We have a solar program, but our projections do not show solar
development contributing much for a long time. Geothermal may contribute 2 or 3
percent, but solar will contribute somewhat less than 1 percent. This is partly because
a new technology takes 30 to 35 years after inception to become commercial, and we
do not see solar becoming commerical before that time.
COMMENT: While we have to have block power for electrometallurgical and electro-
chemical operations, cities, community operations, and major institutions, there is in
solar a strong element of recreation, play, and learning for the individual householder
and apartment dweller that we tend to overlook. People will invest time and money in
solar, even though it may not be economical to do so. Solar technologies developed
over the past 20 to 30 years have been used in the sun belts of the world.
COMMENT: The International Solar Energy Association celebrated its 25th anniversary
recently in Atlanta, Georgia. Based on what I heard there and 25 years of personal
involvement in solar energy, I agree that solar electric power is not going to make
much of a dent before the year 2000. But solar heat is here now, and that is where
the application is. Solar energy is free, but it is expensive to collect it. Once it is
collected, it does not make much sense to throw away most of it by trying to convert
the remainder to electricity. The materials associated with solar energy technology,
whether they be photovoltaics or thermal conversion systems, are energy intensive. It is
hard to think of a more energy-intensive material than silicon, unless it is enriched
uranium, steel, glass, copper, or aluminum. All these are produced in very energy-
consuming industries using hard technology. There is nothing soft about any of them.
QUESTION: When did research begin on the control technology relating to coal?
RESPONSE (Mr. Elder): Some of the fundamentals date back to our first knowledge
of the basic chemical reactions and mechanical components. TVA's activity in the area
of flue gas desulfurization began in the early 1950's, when they built their first
coal-fired power plant. Prior to that, there had been one commercial installation in
England, in the 1930's, which was shut down in the 1940's. Although TVA's activity
began in the early 1950's, the recent comprehensive program with full Federal support
did not begin until the late 1960's.
MR. PRINCIOTTA: We have heard a lot about new developments in control tech-
nology for coal. Which seem to be the most promising or exciting technologies relating
to clean combustion of coal, with particular emphasis on those that might make an
impact in the next several years?
DR. MCKINNEY: The advanced conventional coal-fired boiler and fluidized bed
combustion are probably the most exciting technologies, and EPRI is funding a demon-
stration project with Texaco in southern California on the coal gasification combined
cycle, which looks promising.
MR. ELDER: Although there are some exciting advanced technologies, conventional
combustion appears to be the only near-term choice. In the conventional area, I am
quite disappointed that recovery technology has not gained a higher status in the
utility industry. Most of the technology is based on lime or limestone scrubbing and
results in a throwaway product. This technology has received the bulk of R&D atten-
tion. The potential is certainly there for a recovery technology that will avoid the
creation of another waste disposal problem while allowing recovery of a valuable
resource. Perhaps it is not generally known that there is a projection for a shortage of
elemental sulfur in this country by the turn of the century. Sulfur is a very important
industrial chemical, the supply of which is affected by the energy used in its produc-
tion. It is mined by heating water and pumping the water into the ground, melting the
sulfur, and taking it out. The natural gas used for sulfur production has become quite
expensive in recent years, which is adding to the cost of sulfur. At the same time,
onshore deposits have been depleted and more and more sulfur is coming from
offshore mines. These factors will combine to increase the cost of sulfur and therefore
provide a greater incentive for recovery from coal combustion. In the next 20 years or
so we should try to develop technology to recover sulfur from coal combustion. The
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efforts being made have not been as extensive as is required to get acceptance by
the industry.
MR. SHAPIRO: Apparently the use of additives such as magnesium and the adipic
acids makes lime-limestone very promising, although some problems associated with the
additives have to be considered. The closed-loop operation, sludge fixation, and forced
oxidation are also looking extremely good.
Six or seven advanced processes that appear very promising will probably have to
be pursued in parallel. No one system will satisfy the requirements for all utility sites.
The particular requirements of the individual utility, location of the site, state regula-
tions, availability of coal, and disposal facilities will influence the choice of types of
scrubbing necessary to provide the lowest cost system.
In regard to the regenerable sytems to recover sulfur, even if the sulfur does not
turn out to be a marketable product, the generation of the sulfur itself would result in
a more easily disposed of waste product. The costs of disposing of pure sulfur versus
some of the other sludges and materials will be less.
I would also like to reinforce the statement that instrumentation and process
controls will be an extremely important area, and a lot of effort should be put forth in
that direction. This is an area that our program in the Department of Energy will be
focusing on. AFB will be expanding very rapidly in the near term, primarily in
industrial applications. Possibly TVA will be sponsoring some development in the
utility size applications, also.
MR. ELDER: The New Source Performance Standard virtually rules out scrubbers as a
particulate control mechanism. That is disappointing because it seems foolish to spend
money for big electrostatic precipitators when we could probably do the same
operation in one device. If, in fact, we are stuck with both precipitators and scrubbers,
we should work on putting the precipitator after the scrubber rather than before.
DR. MCKINNEY: In the advanced conventional fired plants, I assume that we are
going to regenerable FGD and are not going to keep making sludge from now to
eternity.
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QUESTION: Are the utilities informally involved in the R&D selection and structuring
program to ensure that they will use the program you are working on?
RESPONSE (Mr. Shapiro): One objective of the research and development of scrubber
technology is to ensure that coal is a viable option and will be used. We must therefore
involve the people who will be using the coal and will be purchasing the control
technology systems. We expect to work very closely with them, and we anticipate
cost-sharing between utilities and equipment manufacturers. Probably the most
important aspect of the program is to ensure that the technologies developed result in
commercialization and are actually used by the utility sector.
RESPONSE (Dr. McKinney): The Electric Power Research Institute represents the
utility industry in R&D and has advisory committees that approve our projects. We
also have working agreements and informal contracts with both DOE and EPA. The
programs do come back to the utilities.
COMMENT: We have a program in Sweden with American Electric Power which
is probably as advanced as TVA's program for AFBC. We are designing a combustor
that will lead up to the commercial size PFBC in the 200- to 250-megawatt range. We
hope to build a demonstration plant on the AEP system, combining a 70-megawatt gas
turbine and combustor with an existing 110-megawatt steam turbine. We believe that
this has a better potential for sulfur retention, NOX suppression, and lower cost. It will
also lead to more large-scale cogeneration for the large industries, such as petroleum,
chemicals, or eventually district heating applications. We see a potential for much
higher electricity-to-heat output with these systems than we can get with either
conventional steam back pressure systems or AFB back pressure systems. We expect to
see plants operating no later than 1984, although AEP has not made a formal
commitment to start on the hardware; but we are far into phase 2 of the program,
which involves very detailed design of the equipment. So far this is being done on a
shared-cost basis with AEP, but we hope in the next round to get contributions from
other groups as well.
MR. ELDER: There are certainly potential advantages to the pressurized system, but
the viability for the atmospheric unit is closer.
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iba^'otep
& answers
Dr. Edwin S. Rubin
Carnegie-Mellon University
Jean B. Cornelius
Avon Lake League of Women Voters
Doc Hodgins
Friends of Eastport
J. Lee Krumme
Vinings Chemical Company
QUESTION
With respect to industrial applications of fine
particle control in solid and liquid waste effluent, can we
talk about applicability, availability, cost of technology,
and R&D programs envisioned or under way?
RESPONSE: Dr. Leslie E. Sparks (EPA)
The control technology used for industrial boilers
is fabric filters, which are efficient enough to meet the
standards. The novel precipitator will probably be appli-
cable to the industrial boiler after the technology is
demonstrated. We do not, however, have a specific
program aimed at the industrial boiler market.
QUESTION
In the area of FGD wastes, what are some of the
liquid waste FGD systems prevalent in industrial appli-
cations?
RESPONSE: Mr. Julian W. Jones (EPA)
Although the question is aimed at liquid waste,
some specific problems concerning solid waste in the
industrial area must be addressed because of the current
smaller-scale situation. These problems have been identi-
fied in the past year. The long-range effects of the use of
coal are a subject for future work. As to liquid wastes,
dry scrubbing using a sodium base material is probably
the most imminent happening. The problems there would
be quite similar, and the technology associated with
disposal of sodium waste from the dry scrubbers would or
could be applicable to the sodium scrubbers at the
industrial scale.
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QUESTION
Is the fluidized bed combustion process discussed
today similar to the Akron, Ohio, process that mixes coal
with garbage?
RESPONSE: Mr. William T. Harvey (DOE)
The fluidized bed combustion process can utilize
any combination of combustible materials, and the
combustibles can be burned concurrently or serially.
QUESTION
Landfill has been the preferred method of fly ash
disposal for some time. Does anyone know, at this time,
what leachate goes into the groundwaters from it?
RESPONSE: Mr. Jones
This will be a part of a study we will be doing in
support of the regulations. The practice of landfilling
with fly ash has been going on for some time, but we do
not have much information about groundwater
contamination yet. Studies have been done as a part of
our program, some of them conducted by TVA, about
possible groundwater contamination, but the results have
not yet been issued.
QUESTION
There are less traditional pollutants associated with
coal which have not yet been mentioned here. Could
the speakers discuss the latest research on radioactive
nuclides, for example, and on carbon dioxide, selenium,
mercury, nickel, and cadmium? Some very good and
timely studies have been done. What effect will these
pollutants have?
RESPONSE: Mr. Frank T. Princiotta (EPA)
There is absolutely no question that the ambient
concentration of carbon dioxide has increased as a result
of fossil fuel combustion. What the concentrations will be
over the next two decades and how meteorology will be
impacted are being studied in a major, multimillion dollar
DOE program aimed at eliminating some of the uncertain-
ties and identifying the ultimate implications of increasing
amounts of CO2- Every time anything burns, be it
gasoline in an automobile or coal in a power plant,
carbon monoxide is generated. It poses a long-range
problem that will need a long-range solution.
EPA has an active Conventional Combustion
Environmental Assessment program. Its goal is to ascer-
tain some of the untraditional, currently unregulated
problems associated with coal. Some work has been done
on radionuclides, and more in the area of heavy metals
from coal and residual oil as well. Mercury, selenium,
cadmium, and other heavy metals have been studied. The
results to date have been inconclusive. What is clear is
that ambient air impacts of coal burning, relative to these
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heavy metals, are rather trivial; there are very small
concentrations in the air. That is not to discount it as an
environmental problem. Some of these metals, such as
cadmium, can be concentrated by plants and end up in
the food chain and in man via a mechanism other than
breathing. Preliminary results suggest that heavy metals,
at least from coal or fossil fuel combustion, are probably
not a direct ambient air quality problem. Work continues
in this area.
There have been various studies on radionuclides
in coals, the bottom line of which seems to be that the
levels are fairly trivial, but again, work continues. If
the body of research finally indicates that these are
important environmental problems, environmentalists and
legislators will surely initiate appropriate legislation to
control them.
COMMENT
Some of us would like to invest in cogeneration and
other conservation methods, in more benign processes,
while the problems inherent in, for instance, fluidized
bed combustion are resolved. We would like to see the
environmental problems solved beforehand rather than
retroactively. We want benign energy sources that support
our traditional society and patterns.
RESPONSE: Mr. Princiotta
The amount of electricity produced can be in-
creased in three major ways—by nuclear power plants,
coal-fired power plants, and combustion of oil and gas.
Those are the three viable near-term options.
QUESTION
In sodium scrubbing, dilute solutions of sodium
metab/sulfite are being well-injected. These bisulfite
solutions contain minute quantities of benadium, as well
as particulate matter and copper. What is to be done
with these well-injected sodium metabisulfite .solutions?
Do you plan to issue any guidelines toward the discon-
tinuance of well-injecting?
RESPONSE: Mr. Jones
In general, we tend in our program to concentrate
on the big problems. Should sodium scrubbing become
a major approach to control, the disposal or treatment
of those particular streams would become a part of our
program, because it would be of concern to the regu-
latory part of the agency.
COMMENT
There have been some negative thoughts expressed
concerning the willingness of the government to listen
to comments about achieving a benign environment.
Washington appears to have a large number of people
working hard to achieve such an environment. However,
what sometimes appears initially to be benign may not be
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so benign or risk free. Solar energy, for example, actually
utilizes a lot of glass and metal, both of which are manu-
factured commodities requiring plants that are apt to
cause environmental problems. Everyone, on both sides of
the fence, should try not to feel so defensive. Those
working to achieve adequate energy supplies ought not to
look at environmentalists negatively, nor should the
environmentalists view the energy-minded faction as a
different breed of cat. We are all in this together and
should be listening and cooperating.
158
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YM
session 4
cean
IJVAILf fits
environment
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THE AMOCO CADIZ OIL SPILL
Wilmot N. Hess, Ph.D.
Environmental Research Laboratories
National Oceanic and Atmospheric Administration
U.S. ASSISTANCE
MOUSSE
The AMOCO CADIZ oil spill produced the greatest impact on the environment
of any oil spill up to that time. The spill occurred on March 16, 1978, 2 miles off
the coast of Brittany in the northwest corner of France, near the little fishing village
of Portsall (Figure 1). This ship ridded itself of its 220,000-ton load of light crude
oil in about 2 weeks.
A United States team consisting of biologists from EPA, physical and chemical
oceanographers from NOAA, representatives of the Coast Guard, and university
members were on the scene within about 3 days. The team had previous experience
with the ARGO MERCHANT spill. Ascertaining that the French would welcome
assistance, they went in to help in such tasks as sampling oil in awkward situations,
measuring the extent of the oil slick, and mapping oil on the beaches.
The AMOCO CADIZ broke in half on the second day and into three parts
later on (Figure 2). Oil from the wreck spread rapidly, driven eastward along the shore
by the wind, but very little got as far east as the Gulf of St. Malo or the Channel
Islands. The major area impacted was along the coast of Brittany from Le Conquet to
the Sillon de Talbert where winds from the west and northwest drove the oil directly
onto the shore. Two estuaries directly faced the oil, and the northward-extending
beaches about 100 kilometers to the east of the site of the spill received especially
large amounts.
From the air, Portsall looked charming and pleasantly idyllic but at close range
not quite so idyllic. The area around the village and for a considerable distance to the
east had large deposits of mousse—the emulsion that results when crude oil interacts
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H
" **- r'l
/ < !ji •!•»« i . i
< »/
CHANNEL ISLANDS
(IJ.KS A'OR MANORS
'T tl . . «
'' .v-li"'!
1 -«\,
, v'' •
!
Gram <• -
6HliUi i V
. ' t
,' • B
.'
.' •^^ J^'^'^k. h I WOLW .^_ . . \-±- fL
FIGURE "(—Map of Brittany coast of France with wreck site marked by dot
FIGURE 2-Photo of AMOCO CADIZ on March 28, 1978
162
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PLASTERED AGAINST
THE BEACHES
A TOWN HEAVILY
IMPACTED
with water (Figure 3). Mousse is typically two parts water to one part oil. It is the
color and consistency of chocolate pudding and is extremely difficult to clean up.
In the first 2 weeks, oil impacted about 140 kilometers of coast. Our team
selected certain beaches on which to measure the effects, persistence, and amount of
oil. It did not accumulate uniformly throughout the region, but in selected areas. It
was driven by the wind into corners and plastered against westward-facing beaches.
Eastward-facing beaches were almost unaffected for the first 3 or 4 weeks. After
a wind shift, the oil got on but in lesser amounts and with less damage because about
40 percent of light crude oil is made up of volatile materials that dissipate into the
air in a matter of days. This volatile component contains many of the more toxic
elements, so that after about a week the material becomes more benign.
The town of Roscoff was also heavily impacted (Figure 4). The wind-driven
oil butted up against a jetty and puddled into some areas of the harbor. It extended
past the jetty and around a point, yet had little impact on the eastward-facing beach
for some period of time. Of about 30 standard sampling beaches, 2 were located in the
Roscoff region.
. • ~v_ ^j .
FIGURE 3-Photo of heavily oiled beach at Portsall
FIGURE 4-Photo of harbor at Roscoff, showing heavv oiling especially in eastern corner
where the wind drove the oil
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SELF-CLEANSING AREAS
Oil does not necessarily stay on beaches for long periods of time (Figure 5).
Underground water flowing out through a beach, for example, tends to cleanse the
beach. For the first 10 days or so, oil is mobile. At high tide it gets deposited and,
as the tide backs off, a reasonable amount remains on the beach. This oil, however,
is fairly easy to clean up. After about 10 days or more, the oil becomes much more
sticky. It adheres to sediments and is not easily washed off.
In areas of high-energy active waves against a headland, oil is held off the beach
somewhat. Reflecting waves prevent it from accumulating directly on rocks. These
areas are essentially self-cleansing, and therefore no action was taken by the cleanup
troops to get rid of the oil. Regions can be classified according to their vulnerability to
impact. These promptly self-cleansing areas have the lowest vulnerability.
The characteristics of beaches change from day to day, depending on factors
such as the direction and strength of the wind and the sand deposited or eroded.
Oil under the sand on one day may be washed out on the next as a result of erosion.
Therefore, the team from the University of South Carolina went down the beaches
about every 3 days, drawing an elevation of the beach, characterizing the beach for oil
content, and, where necessary, digging holes to measure buried oil. Done regularly
along several transects for each of about 40 beaches and irregularly for another 100
beaches, this produced a good record of where the oil was, what its character was, and
how much of it stayed there or went elsewhere eventually.
FIGURE 5—Photo of oiled beach where the ocean has cleaned the lower portion of the
beach
PECULIAR MORTALITY
DELAY
About 100 kilometers to the east of the spill site, a large amount of oil puddled
against the northward-facing beach at St. Michel en Greve (Figure 6). This region was
heavily oiled about 10 days after the wreck, causing extensive mortality of benthic
fauna. Oil arrived at the beach on March 22, yet the mortality was not observed until
about 10 days later. I walked that beach on April 2 and found up to 30 million dead
animals along a stretch of about 4 miles (Figure 7). There were shells of clams, sea
urchins, and cockles (Figure 8). Two days before my walk, however, a team had
walked the same beach and had seen hardly any dead animals. Is there a delay built
into this kind of process? Most of the creatures found dead on the beach were subtidal
as opposed to intertidal and live below the tideline inside the sediments. It may be
164
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'B$r. :•:"•:•" ' ..•. \Bodw.
v&ufd«" 'V%:
• • §.<*•'• '-•
-2 ' V ,-.,
.*••• .u-> . j
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FIGURE 6—Map of northward trending coast about 100 km east of wreck site. St. Michel en
Greve at southern end and lie Grand near northern end were heavily oiled as shown by the
dark spots
FIGURE 7-Photo of St. Michel en Greve beach on April 2, 1978, showing millions of dead
marine invertebrates
165
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FAUNA LOSS
that the animals started dying when the spill hit and, for reasons we do not under-
stand, suddenly washed up on the beach 10 days later. It is also possible that a
physical process not clear to us was operating. Chemists suggest that toxicity may
change dramatically when oil is exposed to light. The first week after the wreck the
weather was very bad and a continuous cloud cover prevented photooxidation. About
April 1, light came through and photooxidizing compound changes were observed in
chemical traces of oil samples. Whether the changes were great enough to influence the
toxicity substantially is not clear, but this cannot be discounted as a possible explana-
tion for the peculiar mortality delay.
FIGURE 8—C/oseiip photo of St. Michel en Greve beach on April 2, 1978, showing dead
razor clams and cockles and sea urchins (scale is 15 cm long)
In the He Grande marsh to the north (Figure 6), but still on the west-facing
beach, oil puddled into the salt marsh. When oil arrived on March 22, about 10,000
tons puddled into the 100-acre marsh during the first day, creating a mousse on the
marsh 10 or 20 centimeters thick (Figure 9). Ten centimeters of mousse was enough to
smother most of the organisms there, and the number of fauna lost was very high.
Almost all creatures living in the impacted area of the marsh were destroyed. There is,
however, a bridge at lie Grande marsh, and as soon as the oil arrived the area under
the bridge was closed off; thus one side of the marsh was left essentially untouched.
FIGURE 9-Aerial photo of lie Grand salt marsh in early April 1978. This roughly 100-acre
marsh has roughly 10,000 tons of mousse deposited on it.
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FIGURE 10—Photo of mousse pool in lie Grand salt marsh on April 2, 1978, showing dead
worms and "bowls of spaghetti" which were bunches of dead worms
Some animals survived right through the spill. The marine lugworm, Arenicola,
did well in St. Michel, although other marine worms were having lots of difficulty.
About 10 days after the spill in the Me Grande marsh, clumps of dead worms,
polychaetes, were discovered in pools (Figure 10). Apparently they were forced out of
the ground by the oil and tried to find the last bit of fresh water. Water tends to
puddle in the marsh, and the worms collected in spaghetti-like masses in the pools.
On digging in the marsh, we found the kill of polychaetes to be almost total. Sea gulls
in the area, however, were eating the meat of the dead razor clams and having a grand
time. Lethality and mortality are sometimes relative terms.
FIGURE "("(-Photo of dead cormorant at He Grand, April 2, 1978
167
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DEAD BIRDS
INEFFECTIVE BOOMS
Although our team did not see a great many dead birds, the loss caused by
the spill is probably 10,000 to 20,000 (Figure 11). Dead birds were collected mainly
by bird hospitals in the area. The estimate is based on the collection of approximately
4,000 birds and the inefficiency of the collection process. The birds were primarily
auks, puffins, guillemots and razor bills, species that spend much of their time in the
water and are susceptible therefore to damage from oil in that water. The puffins were
especially susceptible during this period because they were molting and therefore
spending weeks in the oiled water. Approximately 700 puffins were found dead. The
southernmost population of puffins in Europe was on Seven Islands (Les Sept lies) off
the Roscoff coast. That population has been decimated, perhaps completely lost. It
should be noted that this population was also hurt badly at the time of the TORY
CANYON spill.
There was not an especially good or well-tested plan for handling the cleanup, so
the process took time to get organized. The French, however, did a very good job of
getting people and equipment out. The cleanup force was made up of approximately
6,000 army troops, a large number of civilian volunteers, and a very large number of
local residents who were interested in getting the Portsall beaches and hotels cleaned
up for the summer tourist season. In Portsall harbor, where oil tended to puddle, they
put skimmers in place and pumped the mousse directly into vacuum trucks.
The booms that were used were ineffective (Figure 12). There were too few of
them and they were impropely positioned so that oil came at right angles directly
against the boom. In such situations the boom fails if there is more than a half-knot
current and the oil goes underneath. To be effective, booms have to be set at an angle
and must be continually maintained.
FIGURE '\2-Aerial photo of beach at Roscoff, showing boom used to try to keep oil away
from the lobster pound (circular structure in the foreground)
EFFECTS OF DETERGENTS
The major part of the cleanup was done by hand. Walls had to be washed re-
peatedly as new batches of oil came onshore (Figure 13). Although the French policy
was that detergents would be used only offshore at the greater than 50-meter depth
contour 3 to 4 miles out, in actuality detergents were used both onshore and offshore.
In the main the detergents that were employed were much less toxic than those used
at the TORY CANYON spill, and there is no identifiable loss from detergents in this
spill.
The beach at Portsall was oiled every day for weeks. The cleanup crew pushed
the oil around, collected it in whatever containers were at hand, and removed it from
the beaches. The material was loaded into fertilizer carrier trucks, moved to temporary
storage pits above the dunes and from there to large carriers that transported it to
refineries or ships for ultimate disposal (Figure 3).
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FUTURE HEALTH PROBLEMS
COMPLETE HISTORY
SOUGHT
• v^. *&&&
FIGURE '\3-Photo showing seawall being washed with high pressure water to cleanse off
the oil
We have been worried for some time about possible future health problems asso-
ciated with the cleanup of spills. As I stated earlier, a great many volatiles come from
oil and tend to be toxic. The people who worked 10 hours a day in the water handling
oil got a fairly good dose of the volatiles, and, as a precautionary measure, blood
samples and other samples are being taken.
In June, 3 months after the spill, the Portsall beaches were essentially clean and
being used for swimming and fishing (Figure 14). Those who ate the fish reported that
it was good. A rich crop of green seaweed was growing at St. Michel and there was
a good mussel population along the edge of the beach. The lie Grande marsh, on the
other hand, was not in good shape. The French Government had decided that the best
way to get rid of the oil in the marsh was to bulldoze the marsh cover, which in
essence destroyed it. Our team considered this a mistake.
NOAA is now running a research program funded with $2 million by the Amoco
Transport Company that involves 10 teams of investigators from the United States and
10 from France. The teams continue to watch the processes of regeneration, rejuvena-
tion, replenishment, and restoration of populations. There is particular interest in the
restoration of the marsh which is being replanted according to schemes developed by
the Corps of Engineers for stabilizing dredge spoil islands. Monitoring the marsh and
other seriously damaged areas over the next 2 years, coupled with good coverage of
the wreck and good biological knowledge about the area, will give us a complete his-
tory of this spill for a comprehensive idea of the total cost to the environment. The
total biological damage appears to be considerably less than originally estimated.
FIGURE 14-Photo of Portsall beach in June with wreck in background. The beach is now
clean (only dark patches are seaweed). This beach was very heavily oiled in March and April
(see Figure 3)
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Norman L Richards. Ph D
EFFECTS OF CHEMICALS USED IN OIL AND GAS WELL-DRILLING
OPERATIONS IN AQUATIC ENVIRONMENTS
Norman L. Richards, Ph.D.
Environmental Research Laboratory
U.S. Environmental Protection Agency
Intensified oil and gas exploration and development in the United States has
resulted in more and deeper offshore wells. Additional lease tract sales are proposed by
the Bureau of Land Management (Figure 1). This activity has heightened concern
KEY
17
7-8
FIGURE ^-Tracts proposed for oil and gas exploration and development
ATLANTIC COAST
1. NORTH ATLANTIC
2. MID-ATLANTIC
3. SOUTH ATLANTIC AND BLAKE PLATEAU
GULF OF MEXICO
1 4. EAST GULF
5. CENTRAL GULF
6. WEST GULF
PACIFIC
7. SOUTHERN CALIFORNIA BORDERLAND
B. SANTA BARBARA
9. NORTH AND CENTRAL CALIFORNIA
10. WASHINGTON-OREGON
ALASKA
11. COOK INLET (STATE-FEDERAL)
12. SOUTHERN ALEUTIAN SHELF
13. GULF OF ALASKA
14. BRISTOL BAY
15. BERING SEA SHELF
16. BEAUFORT SEA
17. CHUKCHI SEA
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DRILLING FLUIDS
FATE AND EFFECTS
RESEARCH
REGULATORY FRAMEWORK
over the potential for environmental effects of drilling. The purpose of this paper is to
(a) review the state-of-the-art in drilling fluids effects research, (b) summarize the
interagency regulatory authorities that provide the present basis for offshore oil and
gas decisionmaking, (c) state some examples of the limits of technical understanding
of processes that could be impacted by offshore development, (d) propose a technical
approach to the potential problem that could result in an improved basis for decision-
making, and (e) review some recent achievements in drilling fluids-related research.
Recent environmental impact statements on oil and gas lease sales have devoted
disproportionately little discussion to the environmental aspects of chemical use in
well-drilling operations. This may reflect the fact that few studies have been done, and
most are acute static toxicity tests that have little relevance to natural conditions
where drilling mud discharges occur (1). Of those acute toxicity tests in the literature,
few report adverse effects of drilling fluids or their components. Field observations
have revealed a variety of marine life in the vicinity of drilling rigs (2). It is generally
assumed that fluids either would have a limited local effect near the plume discharge
point or would be dispersed rapidly and diluted in the field (1). Also, it has been
assumed that many constituents of drilling fluids are sparingly soluble in seawater and,
therefore, might be less biologically available to marine organisms. However, the
assumptions have not been substantiated by peer-reviewed research publications.
Research on the environmental effects of drilling fluids and cuttings is further
impeded by the chemical complexity of the mixtures of crude chemicals used to
formulate mud; drilling fluid is a mixture of clay, water, and numerous chemical
additives that is pumped downhole through the drillpipe and drillbit; mud cools the
rapidly rotating bit, lubricates the drilling string as it turns in the wellbore, carries rock
cuttings to the surface, and serves as a plaster to prevent the formation from crumbling
or collapsing into the wellbore. Drilling mud also provides the weight or hydrostatic
head to prevent extraneous fluids from entering the wellbore and to control downhole
pressures. Chemical ingredients used to formulate mud can include everything from
pH-control products, bactericides, calcium-removers, corrosion inhibitors, defoamers,
emulsifiers, filtrate reducers, flocculants, foaming agents, lost circulation materials,
lubricants, shale-control inhibitors, surface-active agents, thinners, dispersants, and vis-
cosifiers to weighting agents (3). Analyses of potential effects of chemicals used in
well-drilling operations must also take into account variations in mud and cutting
composition related to type of substrate drilled, well depth, availability of mud com-
ponents, temperatures generated, relative cost of components, operator experience, and
so forth (2).
Consider the chemical complexity of drilling fluids, the diverse geographical
conditions of areas being drilled, varying oceanographic conditions, the broad spectrum
of aquatic organisms that could be exposed to drilling fluids during different seasons in
different geographical locations, that very little is known about the basic biology
of marine systems (4), and the resource-intensive nature of offshore research. It is not
surprising that there is a dearth of peer-reviewed papers published in scientific journals
on the effects of drilling fluids on marine organisms. Except for the present research
that was sponsored through the Interagency Energy/Environment R&D Program and a
few studies funded by Bureau of Land Management (BLM) (5, 6, 7, 8), most other
studies in the United States were funded by oil companies and performed by con-
tractors, often in response to federal government regulations (9). These studies were
either (a) attached by the BLM to particular tracts offered for lease, (b) required as a
drilling permit condition of approval by the U.S. Geological Survey (USGS), or (c)
associated with Environmental Protection Agency National Pollutant Discharge Elimin-
ation System (NPDES) permits. Only a few copies of reports that result from these
studies are printed; the scientific community does not have an opportunity to critique
the conclusions before or after publication.
The sequence of federal agency involvement in offshore oil and gas drilling
operations has been described by Richards (10) and is illustrated in Figure 2. The
process that allows private firms to purchase offshore leases involves a sequence of
activities. The National Oceanic and Atmospheric Administration has authority to
designate ocean areas with distinctive value as marine sanctuaries if presidential ap-
proval is received (11). Following a preliminary environmental impact assessment,
172
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EPA LEGISLATIVE AUTHORITY
tracts are offered for sale by the BLM. A solicitation of nominations is accepted
whereby industries can express interest in a tract, and environmental groups, states,
and so forth can register objections (negative nominations). A draft environmental
impact statement is then offered to federal agencies for comment. For example, the
National Marine Fisheries Center of the U.S. Department of Commerce may comment
on marine resources. The Geological Survey may comment on seismic activity; the
Fish and Wildlife Service, on rare and endangered seabirds; state governments, on
potential effects of development on resources or potential onshore impacts, and so on.
Following public hearings, the decision to lease for exploration and for ultimate
development is rendered. Tracts that are leased for exploration may ultimately be
developed for production. If this occurs, oil companies are required to comply with
specific operating orders that are monitored and enforced by the U.S. Geological
Survey.
An offshore operator must possess a valid and final NPDES permit from EPA.
NPDES permits are issued by the EPA regional office that has jurisdiction over the
drilling activity. The permit can stipulate a wide range of discharge requirements that
depend on the Regional Administrator's assessment of the environmental damage
DRAFT
EIS
^.
_i
CO
MARINE
SANCTUARY
DESIGNATION
<
<
o
2
FINAL
EIS
•S.
_i
00
STIPULATIONS
NPDES
PERMIT
APPLICATION
0-
NPDES
PERMIT
ISSUANCE
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w
EXPLORATORY
DRILLING
PRODUCTION
ABANDONMENT
FIGURE 2—Sequence of federal agency involvement in offshore oil and gas drilling
operations
173
-------
HAZARD ASSESSMENT
EXPOSURE ASSESSMENT
likely to arise from the discharge. It is obvious that a high level of technical under-
standing of potential impacts is necessary to avoid over- or under-regulation. Table 1
illustrates the region-by-region diversity of areas, resources and additional concerns that
are part of NPDES permit issuance.
Ongoing and future research is designed to assess the potential hazard to the
aquatic environment and man from drilling practices and to evaluate mitigating
options. Oil and gas drilling hazard assessment is based on (a) exposure assessment and
(b) effects assessment. Figure 3 illustrates that potential damage to marine organisms
may be predicted through knowledge of (a) environmental concentrations of xeno-
biotics that result from discharges and (b) the duration of exposure likely to be
encountered by feral organisms under worst-case-exposure conditions. A hazard assess-
ment based on knowledge of effects and environmental concentrations produces a
better foundation to predict the environmental consequences of drilling. Mitigating
options can be more easily selected from the spectrum of alternatives available to the
region through permit issuance.
Figure 4 illustrates the stepped sequence of tasks performed in the effects assess-
ment component of hazard assessment. It includes an iterative loop between field and
laboratory research. The pyramid is based on a knowledge of chemicals used, but
information is inadequate because (a) over a thousand trade-name products are used in
drilling fluid formulation (12), (b) many components are known only by generic name,
not by chemical composition, (c) most operators are unwilling to release drilling mud
composition information, and (d) no drilling fluid plume and cutting studies have been
published in scientific journals.
EPA exposure and effects assessment research needs to be closely coordinated
in order to arrive at a hazard assessment with environmentally realistic concentrations.
TABLE 1
Special concerns: oil and gas development
EPA Region/Area Representative Areas
Resources
Other Concerns
1 N. Atlantic
II Mid-Atlantic
Georges Bank
Baltimore Canyon
Commerical
Fishery
Commercial
Fishery
Slumping
IV S. Atlantic
E. Gulf of
Mexico
V Great Lakes
Blake Plateau
Florida
Middlegrounds
Lake Erie
VI Gulf of Mexico Flower Garden Banks
(Central & Gulf Coast
West)
IX California
Santa Barbara
Channel
Tanner Bank
X Pacific N.W. Beaufort Sea
& Alaska
Commercial
Fishery
Coral Reefs
Drinking Water
Commerical
Fishery
Coral Reefs
Commercial
Fishery
Marine Mammals
Commerical
Fishery
Coral Reefs
Commercial
Fishery
Marine Mammals
Ice
Salinity
Eutrophication
Seism icity
Ice
Weather
Assimilative
Capacity
Seism icity
174
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EXPOSURE
ASSESSMENT
EFFECTS
ASSESSMENT
HAZARD
ASSESSMENT
FIGURE 3-Environmental considerations in drilling permit issuance
EXPOSURE
ASSESSMENT
<*^^
ENVIRONMENTAL
CONCENTRATION ASSESSMENT
FIELD
RESEARCH
OPERATION
MONITORING
BASELINE AND TREND MONITORING
TRANSPORT AND DISPERSION
FORMATION COMPOSITION
OCEANOGRAPHIC PARAMETERS
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CHEMICAL FORM
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/ (NOMINAL CONCENTRATION)
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DEVELOP/APPLY CRITERIA FOR XENOBIOTIC SELECTION
FIGURE 5—Stepped sequence of toxicity tests to assess xenobiotic effects on estuarine and
offshore organisms
XENOBIOTICS ANALYSIS
Figure 5 illustrates the conceptual basis for a stepped sequence of laboratory and field
toxicity tests designed to assess drilling fluid effects on marine organisms and com-
munities.
Preliminary screening of selected compounds is accomplished by acute static
toxicity tests. Conducted with drilling fluids or their components, these range-finding
tests aid in selecting toxicant concentrations for subsequent flowing seawater bioassays
of each compound, component, or mixture of interest.
Flow-through toxicity test methods were selected for a higher tier of testing
because they more nearly approximate in situ conditions. In contrast to static tests,
metabolic products and excreta are removed, while oxygenated seawater and toxicant
are continuously supplied. Data obtained from flow-through toxicity tests are generally
preferable over static tests as the more precise measure of toxicity and bioaccumula-
tion. A few compounds are selected from flow-through experiments for the next tier
of testing: effect on composition and functions of estuarine communities.
The effect of selected xenobiotics on colonization of planktonic larvae and
microorganisms is analyzed by means of the apparatus and methods developed at
the Gulf Breeze Laboratory (13). Seawater, with its natural components of plankton
and microorganisms, is pumped to the laboratory and into the primary constant head
box. Xenobiotics are continuously metered into the water after they are siphoned from
a constant head box; the control apparatus receives the same flow of water. Water then
flows from the secondary constant head box to each of 10 adjacent aquaria, that is 10
replicates for each treatment, including controls. At the end of an exposure period,
microflora, macrofauna, and meiofauna are sampled. To determine the effect of the
176
-------
xenobiotic after each treatment, numbers and species of microflora, meiofauna, and
macrofauna in control and exposed aquaria are compared, and concentrations of
xenobiotics in test water and sediment are determined. Samples of water from the
constant head boxes are taken for xenobiotic analysis, and sediment cores from aquaria
are taken from each apparatus at the end of the exposure. The tiered toxicity tests
used in effects assessment have the following features:
• There is a continuing iteration between field observations and laboratory
research.
FATE AND TRANSPORT
• Relatively inexpensive and rapid rangefinding tests are used to minimize more
resource-intensive tests.
• Community structure tests (14, 15, 16, 17, 18) can be used to detect both
sensitive and resistant species for subsequent detailed testing.
• Effect and no-effect concentrations can be found expeditiously.
• The data can be used to estimate bioaccumulation rate, application factors, and
maximum allowable toxicant concentration.
Research tools for predicting the potential environmental fate and effects of
drilling fluids are now becoming available. Figure 6 was composed from the plume data
of Continental Shelf Associates (20) and community profile studies by Bright (21).
Under the conditions studied, a near-surface discharge of drilling fluid did not disperse
uniformly but concentrated above the thermocline (20). Adequate research has not
been accomplished to determine the probability that a similar transport mechanism
could ultimately cause exposure of coral reef communities in the Texas Flower Garden
Banks. However, Figure 6 does illustrate that the potential for direct and/or indirect
drilling fluid exposure via thermocline transport should be investigated under different
hydrographic regimes. Shunting (discharging the drilling fluid to the nepheloid layer)
has been proposed as an alternative to surface discharge (see broken line Figure 6).
However, information on the transport and fate of shunted drilling fluids is inadequate
for making an informed decision on the relative merit and hazard associated with
shunting.
DRILLING MUD BARGE
-\ f
COMMERCIAL AND
RECREATIONAL FISHING
o~
NATURAL NEPHELOID LAYER
EXPLORATORY
DRILLING
FIGURE ^-Composite diagram of drilling fluid fate (composite drawn from: Bright, T. J.
Proc.. Third Int. Coral Reef Symp., May 1974, pp. 40-46; Continental Shelf Associates.
A. Report for American Natural Gas Production Company 1978; Richards, N. L.: Proc.:
Env. Effects of Energy Related Activities on Marine IEstuarine Ecosystems. 1977
EPA-60017-77-111)
177
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EFFECTS ON CORAL
PERMITTING OPTIONS
Texas A&M University and EPA Environmental Research Laboratory at Gulf
Breeze have a combined research program designed to determine the direct and indirect
effects of drilling fluids on corals, coral communities, and coral reef processes. Current
EPA experiments are run at a research laboratory located 12 miles offshore at Panama
City, Florida. The purpose of this program is to determine concentrations of drilling
fluids that affect the survival of corals. This research will be validated in offshore
experiments.
Laboratory experiments on the effects of drilling fluid on benthic communities
are part of the tiered toxicity tests diagrammed in Figure 7. Similar results of experi-
ments with drilling fluids and their components on benthic estuarine organisms have
been published (14, 15, 16, 17, 18, 19). Figure 7 illustrates the effects on aquaria
containing sand initially covered with a 2 mm layer of drilling fluid on the com-
position of communities that developed from settled planktonic larvae in flowing
seawater not containing sand. The average numbers of annelids, arthropods, and
porifera were significantly less in treated aquaria than in untreated aquaria.
EPA regional offices face a spectrum of regulatory options concerned with the
discharge of drilling fluids into aquatic environments. Table 2 summarizes some of the
options. Although completely adequate and timely data are not likely to be available
now for NPDES permit issuance, regional offices must make the best possible decision
from the limited data available. Ideally, both over- and under-regulation should be
minimized through timely and scientifically defensible research. In this way, scientifi-
cally gained data on environmental concentrations and toxicological effects of drilling
fluids may help eliminate unjustified concern about certain chemicals being used in
drilling fluids. Similarly, modified operating procedures or drilling fluid ingredient
substitution may help mitigate environmental effects that are observed in region-
specific field- and laboratory- based research programs.
C/J
LL.
O
DC
LLJ
00
70
60
50
40
30
20
10
ANNELIDA
CONTROL (SAND ONLY)
DRILLING FLUID (2mm OVERLAY)
ARTHROPODA
PORIFERA
COELENTERATA
MOLLUSCA
CHORDATA
PHYLA DEVELOPING DURING INCUBATION PERIOD
FIGURE 7—Effect of drilling fluid on development of aquarium community structure
178
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TABLE 2
Spectrum of regulatory options for drilling fluids discharge
• Drilling prohibited
• No-discharge permits
— Barge wastes to remote location
— Ocean disposal at designated dumpsites
— Ocean disposal in abyss
— Land disposal
— Reprocess/recycle
• Limited discharge permit
— Barge portions of fluids/cuttings
—Selective treatment of types of fluids
• Black/gray/white list of components prior to drilling
• Case-by-case permits
— Geographical restrictions
— Special resources
— Rare/endangered species
— Climactic restrictions
— Season of year
• Discharge, but monitor environmental effects/concentrations
• Discharge rate stipulation
—Up to preselected rate
— Bulk discharge prohibition
— Situation discharge (current, mix rate, etc.)
• Shunt
— To bottom
— Below surface
• Restrict/prohibit fishing
• Unrestricted discharge
179
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References
1. Sheen Technical Subcommittee. Environmental Aspects of Drilling Muds and
Cuttings from Oil and Gas Extraction Operations in Offshore and Coastal Waters.
1: 1976. pp. 1-50.
2. Fisher, F. Conf. Proc. of the Office of Toxic Substances, EPA Environmental
Aspects of Chemical Use in Well-Drilling Operations. Houston, Texas, EPA
560/1-75-004. 1: May, 1975. pp. 1-604.
3. Wright, T. R., Jr. "World Oil's 1975-1976 Drilling Fluids File," World Oil.
1: 1975. pp. 38-71.
4. Parker, P. "Effects of Pollutants on Marine Organisms," Deliberations and
Recommendations of the National Science Foundation. August 11-14, 1974.
5. Alexander, J. E., T. T. White, K. E. Turgeon, and A. W. Blizzard. Rig Monitor-
ing. (Assessment of the Environmental Impact of Exploratory Oil Drilling).
Volume VI. Baseline Monitoring Studies, MAFLA, DCS, 1975-6. Final report to
the U.S. Dept. of Interior, Bureau of Land Management Outer Continental Shelf
Office, Washington, D.C. 1977.
6. Bright, T. B. and R. Rezak. Northwestern Gulf of Mexico Topographic Features
Study. Final report to the U.S. Dept. of Interior, Bureau of Land Management
Outer Continental Shelf Office, New Orleans, Louisiana. 1978a.
7. Bright, T. B. and R. Rezak. South Texas Topographic Features Study. Final
report to the U.S. Dept. of Interior, Bureau of Land Management Outer Con-
tinental Shelf Office, New Orleans, Louisiana. 1978b.
8. Groover, R. D. (Ed). Environmental Studies, South Texas Outer Continental
Shelf, Rig Monitoring Program. Final report to the U.S. Dept. of Interior, Bureau
of Land Management Outer Continental Shelf Office, Washington, D.C. 1977.
9. Gettleson, D. Effects of Oil and Gas Drilling Operations on the Marine Environ-
ment. In press.
10. Richards, N. L. "Responsibilities for Marine Pollution Research Within Federal
Agencies of the United States." In Meyer, S. P. Proceedings of the International
Symposium on Marine Pollution Research. 1976. pp. 5-11.
11. U.S. Dept. of Commerce. Draft Environmental Impact Statement Prepared on
the Proposed East and West Flower Gardens Marine Sanctuary. 1979.
180
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12. World Oil. World Oil's 1977-78 Guide to Drilling, Workover, and Completion
Fluids. Gulf Publishing Co. 1977.
13. Hansen, D. J. "Aroclor 1254: Effect on Composition of Developing Estuarine
Animal Communities in the Laboratory." Contributions in Marine Science.
8: 1974. pp. 19-33.
14. Cantelmo, F R. and K. R. Rao. "Effect of Pentachlorophenol (PCP) on Meio-
benthic Communities Established in an Experimental System." Marine Biology.
46: 1978. pp. 17-22.
15. Cantelmo, F. R. and K. R. Rao. "Effects of Pentachlorophenol on the Meio-
benthic Nematodes in an Experimental System." In Pentachlorophenol. Plenum
Publishing Corp., N.Y. 1978. pp. 165-174.
16. Tagatz, M. E., J. M. Ivey, H. L. Lehman, and J. L. Oglesby. "Effects of
DowicideR G-ST on Development of Experimental Estuarine Macrobenthic
Communities." In Pentachlorophenol. Plenum Publishing Corp., N.Y. 1978.
pp. 157-163.
17. Tagatz, M. E., J. M. Ivey, H. L. Lehman, and J. L. Oglesby. "Effects of a
Lignosulfonate-Type Drilling Mud on Development of Experimental Estuarine
Macrobenthic Communities." Northeast Gulf Science, Vol. 2 No. 1. June 1978.
pp. 35-42.
18. Tagatz, M. E., J. M. Ivey, J. C. Moore, and M. Tobia. "Effects of Pentachloro-
phenol on the Development of Estuarine Communities." Journal of Toxicology
and Environmental Health, 3. 1977. pp. 501-506.
19. Tagatz, M. E. and M. Tobia. "Effect of Barite (BaS04J on Development of
Estuarine Communities." Estuarine and Coastal Marine Science, 7. 1978. pp.
401-407.
20. Continental Shelf Associates, Inc. Monitoring Program for Well #1, Lease OCS-G
3487, Block A-367, High Island Area, East Addition, South Extension Near East
Flower Garden Bank, Vol. I, II. A report for American Natural Gas Product on
Company. 1978b.
21. Bright, T. J. "Coral Reefs, Nepheloid Layers, Gas Seeps and Brine Flows on
Hard-Banks in the Northwestern Gulf of Mexico." Proceedings: Third Inter-
national Coral Reef Symposium. May 1974. pp. 40-46.
181
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questions
& answers
John D. Powell
Holliston Conservation Committee
Dr. Margaret E. Hamilton
Delaware Chapter, National Audubon Society
A. M. Natkin
Exxon Corporation
Peter H. Debes
College of Environmental Science and
Forestry at Syracuse, NY
Richard Wood
Niagara Mohawk Power Corporation
David C. Clink
Automation Industries, Inc.
QUESTION
The plutonium levels in mussels in Plymouth,
Massachusetts were mentioned. That site would be the
Pilgrim I nuclear generator. Boston Edison, which
operates that generator, as a public relations gesture,
created a park at the water discharge area. The public
is free to harvest mussels and fish, to picnic and enjoy
assorted benefits of nuclear generation. As there is
plutonium present in these mussels, would anyone care
to comment on possible health hazards to the public?
RESPONSE: Dr. Donald Phelps (EPA)
The presence of transuranic radionuclides is not
limited to the Pilgrim site, but appears to be part of
a phenomenon of elevated levels. The degree to which
that elevation makes them more or less a hazard to
humans is a research question.
QUESTION
The Nova film, Black Tide, describes where the
oil from the AMOCO CADIZ spill went. Estimates as
to how much was actually dissolved in the water, how
much was deposited on the beaches, carried away, and
so forth were made in the film. At that time, 40,000
to 50,000 tons were still unaccounted for. Has anyone an
idea where that amount of oil went?
183
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RESPONSE: Dr. Wilmot N. Hess (NOAA)
Of the 220,000 tons released, about 80,000 tons
evaporated in the first 10 days and 65,000 tons were
deposited on the beaches. The rest of the oil was un-
accounted for quantitatively because of the inability to
sample widely enough to find out how much was in the
sediments of subtidal regime or in the water column.
Probably a large fraction of that unaccounted for 75,000
tons went into the water column and was widely dis-
persed, but there is no way to go back and reconstruct
that. Later on, as cleanup progressed, much less oil was
on the beaches, because of the action of the cleanup
forces, but considerably more was found in subtidal
sediments, especially in the bays of Morlaix and Lannion.
At the end of the summer it was estimated that there
were 40,000 tons of oil in or resting on the surface of
the subtidal sediments. That oil is gradually going away,
but there is still a considerable amount of oil in the
estuaries. The next update on the status of the oil will
take place in November 1979 at an international con-
ference in Brest.
QUESTION
How long is it estimated to take the fishing and
seafood industries to recover from the effects of the
AMOCO CADIZ oil spill?
RESPONSE: Dr. Hess
The fishing industry is more or less back to normal
now; the oyster culture industry is still in fairly bad
shape. Last year, 9,000 tons of oysters in the bays of
Morlaix and Lannion were destroyed because of tainting.
Oysters ordinarily have about 60 ppm hydrocarbons. The
oysters that were destroyed had a few hundred ppm. The
French government decided it was not worth trying to
depurate them, to move them to a clean area and let
them regenerate, so they destroyed them. It is not clear
how soon those oyster beds will be available for culture
again. It is probably going to be another couple of years.
QUESTION
NOAA is doing a fine job following up on the oil
spills that have taken place, making expert scientific
advice available to the people trying to clean up the
spills, and putting out reports of excellent quality. How
effective might the use of dispersants have been in the
AMOCO CADIZ spill had the French government decided
to use them more widely?
RESPONSE: Dr. Hess
They probably would not have helped very much
close in early on, because the oil came onto the beach in
such large amounts and the dispersants would not have
stopped that. But there were situations where dispersants
probably could have been used to advantage farther away
from the beach and somewhat later when there still were
good-sized oil slicks. Dispersants probably could have
been used there fairly-efficiently.
184
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The United States has not decided upon the proper
posture on the use of dispersants in spills. A feeling that
dispersants should not be used probably goes back to the
time of the TORY CANYON spill when dispersants were
quite toxic. They are not nearly as toxic now. Still, each
situation must be considered carefully to determine that
dispersants will be useful and helpful in dispersing the oil
and letting nature take care of it. In some situations
strong dispersants on beaches do more damage than the
oil. I feel that dispersants should be used more widely
than it is presently considered they should be in the
United States.
QUESTION
Of the approximately 1,000 chemicals mentioned as
currently used in drilling muds, how many have been
specifically tested for toxicity or carcinogenicity, and
what is EPA's policy about using them for drilling before
it has data on these?
RESPONSE: Dr. Norman L. Richards (EPA)
The figure 1,000 was quoted from a summary of
the generic names of chemicals that have been used. It is
a summary published by the American Petroleum
Institute. There are many redundant trade names, and it
is very difficult to go from a generic name to a specific
chemical name. The problem is further compounded by
the fact that even when it is possible to go to a specific
chemical name, the chemicals are often very crude mix-
tures. In fact, some may be only 60 percent of what the
label indicates and the remainder may be an unknown
mixture. When these mixtures of chemicals are pumped
downhole, very complex chemical reactions can take
place, ending up with even more compounds being
formed. Furthermore, when individual components are
tested separately they appear to give a very different
effect than when they are tested in combination. Very
few have been tested, and of those that have been tested,
entirely appropriate organisms have been tested in order
to extrapolate to offshore conditions.
There are no published studies on mutagenicity and
carcinogenicity. Most of the information is available only
in informal reports, and even those have very limited
distribution. Federal agencies, for example, will require
only three copies of a report to be prepared, so it takes
a great deal of detective work to get even the informal
reports. When you do get them, they have not been sub-
jected to peer journal type review. As a result, some
results may be questionable.
Because each of EPA's Regional Offices deals with
problems unique to that office, there is no hard and fast
national policy regarding the use of these chemicals. The
Regional Office issues the NPDES permits. For example,
a great deal of money has gone into investigating
eutrophication problems in Lake Erie. There is local con-
cern that putting concentrated chemicals back into the
lake presents a potential problem that does not now
exist in marine waters. The brine water produced
could add chloride to the water, which in turn could
185
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produce ecological consequences in Lake Erie. Our office
is attempting to provide the unique research information
required by each of the unique problems of the regions.
QUESTION
In view of the current concern over the potential
presence of various toxic chemicals in fresh waters, has
any thought been given to the possibility of an approach
similar to Mussel Watch for fresh waters using freshwater
species?
RESPONSE: Dr. Phelps
Although I am not aware of such an approach for
freshwater at this time, the concept certainly is applicable
and expandable. The basic ingredient is designating a
suitable organism that has a ubiquitous distribution and
does not move around a great deal.
QUESTION
In view of the obvious castastrophic effects of
oil incidents similar to the AMOCO CADIZ, what is the
feasibility or practicability of using incendiary devices to
prevent the oil from getting ashore by burning it in the
ship?
RESPONSE: Dr. Hess
That has been done several times. It was tried at the
TORY CANYON, but it did not work very well. It was
tried in a spill on ice in Buzzards Bay a year ago, and it
did work to a limited extent there. The problem is to get
the oil puddled and wick it somehow, and to apply a high
enough temperature to cause it to burn well. One of the
problems is that if the slick is some distance away from
the ship, it is generally thin enough so that it is very
difficult to get the temperature up high enough to get it
to burn. If the decision is made to burn the oil at the
ship, the first thing that must be done is to open the
ship. This was tried unsuccessfully at the AMOCO
CADIZ. It was tried at the TORY CANYON with in-
different success. Looking at it logically, even if you do
get the ship open and set the oil on fire, what have you
really accomplished? You have burned material which
might have evaporated anyway. You may have helped by
doing that, but it is rather unlikely that you really will
successfully burn most of the heavies in the crude.
186
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session 5
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SATELLITE OBSERVATIONS OF PERSISTENT
ELEVATED POLLUTION EPISODES (PEPE)
Walter A Lyons. Ph D
Walter A. Lyons, Ph.D.
MESOMET, Inc.
INTRODUCTION
LONG-RANGE TRANSPORT
A new way of visualizing natural phenomena often helps us crystallize our
understanding of basic physical processes. The recently appreciated ability of
conventional meteorological satellites to routinely detect massive areas of turbidity in
the atmosphere produced by both natural and anthropogenic sources has shed new
perspectives on the problem of long-range pollution transport. This paper summarizes
some of the observations of major aerosol events in the atmosphere and suggests that
routine detection and tracking of synoptic scale pollution episodes, along with
quantitative measurements of their intensity are entirely feasible with existing
spacecraft and data analysis systems.
Long-range transport of certain long-lived atmospheric pollutants was graphically
demonstrated 3 decades ago by the tracking of nuclear bomb debris, in some cases,
for several circuits of the globe. The Clean Air Act of 1967 and 1970, however, had
an underlying assumption that the concentrations of various primary pollutants at
some unspecified distance, but not too far downwind from the source, would become
indistinguishable from the natural background because of dilution, wet and dry deposi-
tion, and perhaps chemical transformation. During the 1970's, we have gradually come
to realize how chemical transformations also generate secondary pollutants in signifi-
cant concentrations, which become of greater concern at distances typically greater
than 100 km (White et al., 1976).
Photochemical oxidants were measured by Blumenthal et al (1974), being
exported out of the Los Angeles Basin at the rate of 100 tons/hour. Lyons and Cole
(1976) noted that high ozone values recorded in both urban and rural sections of
Wisconsin were the combined results of local emissions, mesoscale transport, and
synoptic transport, all comingled in a manner making it most difficult to separate the
fraction resulting from each mechanism. Coffey and Stasiuk (1975), Wolff et al (1977),
and Ott and Lyons (1977) were among many suggesting that ozone-laden air masses
could easily travel hundreds or even thousands of kilometers over several days. Periods
-------
SO2 EMISSIONS % «) «>£
25TONS/KM2/YEAR Y/ AO 0
FIGURE \-Map of regions where SO? emission density exceeds 25 tons per square kilometer
per year
190
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SULFATE AEROSOLS
of elevated ozone in air masses undergoing long-range transport were also found
associated with reduced visibility by Samson and Ragland, (1977). As research
continued, such as project MISTT, it became clear that important secondary aerosol
producing mechanisms were being found. The conversion of SO2 gas into aerosols
within individual power plant or urban plumes was documented by many, including
White et al (1976). The progressive deterioration of regional visibility during summer
appears correlated to the increased SC>2 emissions into the upper portion of the
boundary layer by the greater use of coal, as well as higher stacks, (Husar, 1978).
The prime contributor to widespread areas of turbidity appears to be the
conversion of SC>2 gas to sulfate aerosols, with transformation rates somewhere around
1 to several percent per hour, according to Wilson et al. Figure 1 maps the region with
the highest SC>2 emission densities in the United States. The contributions of the coal
burning power plants, especially in the Ohio River Valley and surrounding areas, are
significant. The isopleths of maximum recorded sulfate levels (Figure 2) show the
pattern centered near the major source regions, but with values exceeding 20 /jgm/m3
possible almost anywhere in the eastern United States. It is in this area that our search
for satellite images revealing large scale pollution episodes will be focused.
MAXIMUM OBSERVED
SULFATE VALUES
MAY-OCT .1976
FIGURE 2—Plot of observed maximum sulfate values
through October, 1976
V-
at NASN sites during May
191
-------
GRAPHIC EXAMPLE
A graphic example of air mass pollution was provided by Samson (1979).*
Figure 3 is a view looking southeast from atop Whiteface Mountain in upstate New
York at 1400 EOT, 26 August 1977. Back trajectory computations indicate the air
to be of Canadian origin. Visual range appears to be well in excess of 20 n.mi. Figure
4 is a picture taken at exactly the same spot, looking in the same direction, at 1400
EOT, 28 August 1977—only 48 hours later. Trajectory analysis showed this air mass to
have originated to the southwest of New York state. The visibility has dropped to
several n.mi.
SATELLITE DETECTION
OF AEROSOLS
Reduced visibility or visual range is the result of the decreasing contrast of a
distant object against a background caused by the scattering of light into the inter-
vening volume of air. It is reasonable then to assume that measurements of visible
wavelength radiation from an orbital platform would reveal both increased atmospheric
brightness (turbidity) and reduced contrast of ground targets. The overall measurement
would of course be a function of the aerosol constituency, size, and concentration, the
albedo of the surface, the solar angle, the position of the spacecraft, and the sensi-
tivity, resolution, and spectral response of the sensor.
As early as 1971, Mohr noted anomalous areas of turbid air in ESSA satellite
APT images over Europe and suggested the possibility of using conventional weather
satellites to monitor regional air pollution events. In the same year, McLellan (1971)
had some success in using the digital brightness readings from the geosynchronous ATS
satellite to detect the smog buildup in the Los Angeles Basin by its enhanced upward
light scatter.
'Personal communication
FIGURE 3-View looking southeast from Whiteface Mountain, New York, 1800 GMT, 26
August 1977. A clean polar air mass dominated the area.
192
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METEOROLOGICAL
SATELLITES
Various satellite platforms are capable of detecting a wide variety of aerosol
episodes in the atmosphere. Landsat images were analysed by Lyons and Pease (1973)
and Lyons (1974), revealing point source smoke plumes traveling for more than 100
km over Lake Michigan. Lyons et al (1974) also noted apparent indications of high
turbidity levels throughout entire air masses. Unfortunately the small areal and
infrequent temporal coverage of Landsat makes synoptic monitoring impractical.
The same could be said of 35 mm photography from manned spacecraft missions,
although some individual scenes of note were described by Randerson (1968, 1978).
The operational meteorological satellite, while designed to detect bright, high
contrast clouds, has shown itself suitable for mapping large scale areas of atmospheric
dust, haze, and smoke. The SMS/GOES (Synchronous Meteorological Satellite/
Geostationary Operational Environmental Satellite) series has been used for this
research (Ensor, 1978). Two systems observe the United States from 36,000 km
above the equator, one centered at 75" W, the second at 135" W longitude. Every
30 minutes, subpoint 4 km resolution infrared (10.5-12.5 um) scans of the earth are
made from pole to pole. During daylight hours, visible images at 0.7 km subpoint
resolution are obtained at the same interval. The visual infrared spin-scan radiometer
(VISSR) responds to visible light in the 0.54 to 0.70 um band. Data are transmitted
from the satellite at 8-bit resolution. The enormous data volume (4x10" bits/day) is
managed in many ways, but primarily by conversion to photographic form. However,
special computer-based systems do allow investigations to access and manipulate the
data quantitatively.
FIGURE 4-Same as Figure 3., but exactly 48 hours later. Visibility has dropped to several
miles.
193
-------
MAJOR AEROSOL EVENT
AGRICULTURAL BURNING
Figure 5 is an example of a major aerosol event in the atmosphere—a massive
plume of smoke from the Hawaiian volcanic eruption of September 1977. On subse-
quent days, the plume drifted in a cohesive manner in the trade winds for many
hundreds of miles (Cochran and Pyle, 1978). Shenk and Curran (1974) were among
the first to note the cross-Atlantic transport of large clouds of Saharan dust. During
June 1977 a dust cloud reached Cuba after having left the African coast less than 5
days before, all the while visible in the SMS/GOES visible imagery. During the U.S.
drought of 1977, several major dust storms occurred in the central U.S. One such
raged from 23 to 25 February 1977. On 24 February the satellite detected a plume of
dust stretching from the Oklahoma Panhandle to Georgia (Figure 6). It was subse-
quently seen to spread over the Atlantic as far east as Bermuda. During the passage,
local visibilities dropped as low as 1 to 3 miles (Purvis, 1977). Hi-vol aerosol measure-
ments taken by the Texas Air Resources Board found 24-hour averages ranging from
around 600 jugm/m3 near Houston to as high as 2450 /igm/m3 in northeast Texas.
An often overlooked source of man-made pollution is smoke from agricultural
burning. As noted by Parmenter (1971), massive areas of slash burning in southern
Mexico, Yucatan, and Guatamala during the late winter dry season generated massive
smoke palls over much of the Gulf of Mexico. Figure 7 shows one of the many such
incidents noted in recent years. These smoke-filled air masses frequently reach the
southern U.S.
Smoke from giant forest fires in the western U.S. can routinely be monitored
on SMS/GOES imagery as have massive smoke palls from Florida Everglades fires
FIGURE 5-SMS/GOES 1.0 km resolution visible image, showing plume of smoke from
Hawaiian volcanic eruption drifting several hundred kilometers southwestward, at 0300 GMT,
16 September 1977.
194
-------
1 •••< •
FIGURE 6-SMS/GOES 2.0 km resolution visible image, 1530 GMT, 25 February 1977,
shows cloud of dust stretching from Oklahoma panhandle to Georgia. Dust cloud followed
cold front many hundreds of miles into the Atlantic.
FIGURE 7-SMS/GOES 2.0 km resolution visible image, 1700 GMT, 30 April 1975, showing
large area of smoke over Yucatan and the Western Gulf of Mexico, the result of widespread
agricultural slash burning.
195
-------
MIDWEST HAZE
(Snyder et al, 1976). However, the plume of smoke from a small northern Minnesota
forest fire, is shown in its seventh hour (Figure 8) after having been tracked at 30-
minute intervals from its inception that morning.
Lyons and Husar (1976) presented an SMS/GOES picture, showing a large area
of haze covering the Midwest. Comparisons with other data showed the area to be
associated with reduced visibility (6 n.mi. or less), high sulfate concentrations, and
generally elevated ozone levels. The photograph showed a typical episode—on the scale
of 1,000 km, lasting for several days to nearly 2 weeks, associated with a warm moist
air mass that had significant injections of SO2 from major source regions. That
particular image first needed a certain degree of photographic darkroom enhancement
to make the smog blob or hazy blob or elevated pollution episode clearly recognizable.
Indiana
FIGURE 8-Blow up of SMS/GOES 1.0km resolution visible image, 2200 GMT, 29 September
1976, showing plume of smoke from a small forest fire in northern Minnesota, having drifted
about 100 km southeast after about 7 hours
FIGURE S-SMS/GOES image, 2.0 km resolution, 2200 GMT, 25 June 1975
196
-------
SECONDARY POLLUTANTS
The image described by Lyons and Husar was taken on 30 June 1975, the mid-
point of an episode lasting from before 25 June until after 5 July. Figures 9, 10, and
11 show 1.0 n.mi. resolution images of the eastern U.S. on 25 and 29 June and 3 July
1975. The area of haze, while it did shift its position during this time frame, generally
was more than 25% of the U.S. on any given day. During the end of the episode,
around 3 July, when it was centered in the southeast, elevated ozone values in rural
areas caused notable damage to eastern white pine forests (Hayes and Skelly, 1977).
A persistent high pressure cell during this nearly 2-week long stagnation caused
an accumulation of secondary pollutants from the lower Ohio River Valley, which
were then transported as far as Louisiana and Minnesota. Trajectories produced by
Brand Nieman at Teknekron, Inc. confirm this overall flow pattern by analysis of
FIGURE •\Q-SMSlGOES image, 2.0 km resolution 2200 GMT, 26 June 1975
FIGURE ^-SMS/GOES image, 2.0 km resolution, 1400 GMT, 3 July 1975
197
-------
HOLES IN THE BLOB
IMAGE PROCESSING
150 and 600 m winds. Figure 12 summarizes some of the measurements made on
29-30 June 1975. The visibility contours show that noontime readings (6,4,3, and
2.7 n.mi.) closely correlate to the haze area seen on the satellite image. Those ozone
monitoring sites reporting 1-hour averages of 160 PPB or higher were located in
or near the blob. Scattered sulfate measurements showed values as high as
80 ;ugm/m3 within the haze boundary, and generally 15 /ugm/m3 or less outside.
During the period 27 June to 4 July, persistent southerly winds transported
portions of this blob into Minnesota. Ozone monitors in rural areas of central
Minnesota reported frequent readings in excess of 80 PPB and often above 120 PPB.
This ozone was suspected of being capable of reducing yields of the state's soybean
crop of more than 10% at the level and duration measured (Laurence et al, 1977).
Of note in Figure 10, in addition to the widespread obscuration of ground
features by haze in cloud-free areas, are pockets of reduced turbidity or holes in the
blob. Film animation shows that these travel with the general low-level winds, and
retain continuity for a day or more. There is considerable circumstantial evidence
relating these to areas of wash out by prior thunderstorms. Knowledge of such regions
from satellite images would greatly aid in analyzing surface and aircraft aerosol
measurements. The volume of air undergoing significant wet removal can also be
calculated from such convective footprints if correlated to radar data. A dynamic
real-time data gathering system using color digital remote radar systems now available
would allow for field experiment controllers to monitor the process as it occurs, and
to vector aircraft to begin immediate sampling of pre- and post-convection air mass
aerosol characteristics.
The routine processing of SMS/GOES imagery is geared toward displaying high
brightness, high contrast scenes containing clouds. More gossamer features such as haze
are not always emphasized in prints obtained by satellite image receivers used in
operational weather offices. By proper printing techniques, using 10"x10" archival
quality negatives obtained through NESS (National Environmental Satellite Service),
the haze can be more easily seen. This however involves the added steps of a darkroom
procedure interfering with the real-time acquisition of the pictures. A digital technique
\
FIGURE -\2-Synoptic map, 1800 GMT, 30 June 1975. Shaded areas represent visibility
contours of 6, 4, 3, and 2.7 n.mi. NASN sulfate values (vgm/m3) recorded during June 29
and 30 are shown, and triangles mark oxidant monitors which recorded maximum hourly
values in excess of 160 PPB.
198
-------
has been developed by NESS as reported by Parmenter (1977) which is analogous to
the temperature enhancement of IR satellite data to delineate the subtly different
visible radiances of polluted versus clean air masses. A digital enhancement curve,
similar to those applied to infrared imagery, was found very useful. Figure 13 shows an
example of the NESS technique. The top panel is a segment of a 2 km resolution
image over Florida, as would be seen on a standard weather office satellite receiver.
Application of the digital enhancement makes the band of turbid air across the central
part of the peninsula and surrounding waters highly visible (middle panel). Reported
surface visibilities were under 7 miles within the haze band. Sufficient solar insolation
was reflected as to cause a significant differential in ground heating, as evidenced by
the supression of afternoon convection beneath the haze band (lower level).
FIGURE 13-(a} Portion of SMS/GOES 2.0 km resolution visible image over Florida, 1230
GMT, 15 June 1977. (b) Same scene, but with imagery digitally enhanced using experimental
technique developed by National Environmental Satellite Service. Band of hazy air now
distinct, (c) Same region, but at 2030 GMT, 15 June 1977. Haze was sufficiently dense to
apparently suppress afternoon convection, present both north and south of haze band.
Reproduced from Marmenter (1977).
199
-------
PROBLEM IN HAZE
DETECTION
Another test of the technique was produced on 14 May 1977, when a clean
polar air mass descended into the northeast U.S., causing a displacement of a stagnant,
polluted anticyclone (Figure 14). The enhanced image at 1230 GMT (Figure 15} shows
a clear demarcation of the two air masses, especially over the ocean areas. This
effective digital technique, however, is not routinely available from NESS. Thus
researchers studying such phenomena must rely on darkroom enhancement of prints
made from negatives, or special processing of live or recorded digital satellite data on
special image analysis systems. The problem in sulfate haze detection is therefore not
one of satellite sensor capabilities, but in ground image processing techniques.
FIGURE It-Surface weather map, 1200 GMT, 14 May 1977.
•i
fr3^Vv/??CF
T^.:•"'*.£. r^. »*,•» •T>Xv - '•»- ±U*^
jSfe^5 - i*j?* "
I
y^^^S% .^ ?^o^w
'^/S^f^v •' Haze ;"^' '
Rlf.i':5^H?*i^
Bri^^N'' ^i IbM ,
C«P^^ ;
**"" "fip
*
FIGURE 1S-SMS/GOES 2.0 km resolution visible image, 1230 GMT, 14 May 1977,
specially enhanced by computer processing at NESS. A sharp discontinuity in atmospheric
turbidity is clearly found at the front separating the two anticyclones. linage courtesy of
iv \JA A 11v LL o j.
200
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THE AUGUST 1976
EPISODE
A major episode occurred from 16 to 29 August 1976 over the eastern U.S. and
the adjacent Atlantic waters. This was discussed in detail by Lyons et al (1978).
Figure 16 shows the blob on 22 August 1976. It extended far eastward into the
Atlantic, as far west as Kansas, and southward through the Mississippi River Valley.
The southeastern states were free of haze at this time. Of greatest significance is the
sharp boundary of haziness stretching from southern Minnesota across Lake Huron.
This precisely marked the polar front with 3-5 n.mi. visibilities to the south and 15+
n.mi. to its north. Figure 17 is a map of the 1800 GMT, 28 August 1976 weather
conditions, with contours of the 5 and 3 n.mi. visibilities (corrected for precipitation),
FIGURE W-SMS/GOES 2.0 km resolution visible image, 2230 GMT, 22 August 1976,
showing widespread smog blob stretching from Kansas eastward into the Atlantic Ocean,
with a sharp discontinuity along a cold front stretching east-west across the Great Lakes.
FIGURE IT-Synoptic map, 1800 GMT, 28 August 1976. Overlain on the hazy area
outline as seen on the satellite image, and 3 and 5, n.mi. visibility contours are the
observed NASN sulfate readings (iigm/m3). Readings in excess of 40 >jgm/m3 were found in
low visibility air in Pennsylvania and New York.
201
-------
24-HOUR SULFATE
MEASUREMENT
DATA ANALYZED
QUANTITATIVELY
CONCLUSION
and the boundary of the hazy area seen on the satellite picture. This analysis was
performed for 13 days of the episode. In virtually all cases, the 5-n.mi. visibility
contour lay inside the visible boundary of the hazy blob. It appears that as regional
visual ranges drop below 6 or 7 n.mi., the haze becomes visible in properly printed
SMS/GOES images, especially over water and other low-albedo targets.
Figure 17 also shows the overlain isopleths of NASN sulfate data measured
over a 24-hour period ending 1800 GMT, 28 August 1976. The areas of Pennsylvania
and New York State, where the visibilities were generally lowest and the image
appeared haziest, were associated with 24-hour sulfate levels between 30 and 50
jugm/m3. The sulfate readings made within the hazy area seen on 28 August, 2230
GMT image, averaged 22.7 /j.gm/rr\3 but outside the haze area were only 5.7 /igm/m3.
Similarly, a series of sulfate measurements were made in New York City by
Brookhaven National Lab during this period. When the blob as seen on the satellite
prints covered the area, sulfates averaged 23.7 Mgm/m3, but were only 7.5 ,ugm/m3
when clean air covered the area (Figure 18). This suggests overall enhancements of
sulfate within satellite detected hazy blobs of 3.98 or 3.16 times for these two cases.
Similarly, for each of the 13 episode days, the highest hourly ozone measured at all
stations reported in the National Aerometric Data Bank were plotted. The average for
those sites outside the visible blob was 69.4 PPB, but inside rose to 90.8 PPB, or 30%
higher. This suggests that the correlation of hazy, low visibility air to sulfates is
stronger than to ozone levels. This is partly due to the apparently greater spatial
variability of ozone, as a result of local NOX sources, etc. Table 1 summarizes these
values. Also included are mean values of bscat averaged over the eastern U.S., using
1800 GMT visibilities (with precipitation, fog and high relative humidity samples
removed). The mean bscat value compiled by Rudolph Husar of Washington University
appears to be a useful measure of "episodicity". Values above 3.5 suggest a widespread
and/or intense PEPE in progress.
SMS/GOES data can be analyzed quantitatively, using such systems as the
MclDAS—Man Computer Interactive Data Access System—developed by the University
of Wisconsin's Space Science Engineering Center. Digital data tapes from the August
1976 episode were archived under special EPA funding. MclDAS allows total pixel-by-
pixel manipulations of the imagery. All scenes are navigated and grided, with animation
of sequential images easily accomplished via rapid access from a video analog disk.
A cursor allows the operator to select any number of image pixels and measure the
digital brightness counts (DBC, Range 1-256), which can, by application of calibration
procedures, be converted into radiances. Over water, with apparently clean air masses
present (and confirmed by nearby land visibility of 7 miles or more), DBC's typically
ranged from 40 to 45 units. In hazy but otherwise cloud free areas, values would
usually range from 70 to 85 DBC's. Thus the signal of a hazy air mass in the SMS/
GOES data was clearly well out of the noise level. Over land, typical values in high-
visibility polar air masses during August would be around 60 to 80 DBC's, but could
be as much as 50% higher when apparent haze covered the target. By careful selection
and calibration of ground targets, it appears plausible to use digital satellite data to
routinely obtain a measure of atmospheric brightness, and thus of turbidity, visual
range, and to a lesser degree, sulfates. What the technique lacks in precision it would
appear to compensate for in terms of spatial and temporal coverage particularly over
water, where virtually no routine air quality measurements exist. MclDAS also
processes all available surface and upper air meteorological data. These can be
processed in real-time, and displayed directly on the satellite imagery. Such useful
items as contoured temperatures, surface wind streamlines, 5,000-ft winds, etc. are
just a few of the multitude of outputs available.
The current generation of meteorological satellite data, in photographic and
especially digital form, are capable of synoptic monitoring of the formation, growth,
and movement of large-scale hazy blobs known to be correlated with elevated sulfate
episodes. Details of the long-range transport and removal process can also be studied.
202
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30
20
10
SULFATE VALUES
NEW YORK CITY
AVERAGES
INSIDE BLOB 23.7
OUTSIDE BLOB 7.5
M M
o
£
a
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
AUGUST 1976
FIGURE 18-Sulfate values, 24-hour averages, recorded in New York City, by Brookhaven
National Laboratory from 16 to 28 August 1976. N indicates "smog blob", as seen on the
satellite, was not over the area. Y or E indicates the monitor was in or on the edge of the
smog blob.
TABLE 1
Average of maximum hourly ozone reports inside the "blob" as seen on the enhanced SMS imagery
(PPB), for all NADB stations east of 100° W. Also, the mean bscat determined from NOAA visibility
reports over the eastern U.S. (Source: R. Husar, Washington University), August 1976.
Date
August 16
August 17
August 18
August 19
August 20
August 21
August 22
August 23
August 24
August 25
August 26
August 27
August 28
August 29
bscat
2.98
2.44
2.47
2.52
3.00
3.12
3.35
4.10
4.20
5.02
4.65
4.36
3.59
2.41
Og Inside
(PPB)
69
85
94
97
106
106
89
100
103
93
72
76
O3 Outside
(PPB)
_
69
65
66
81
107
67
77
65
57
77
57
54
AVERAGE
90.8
69.4
203
-------
Figure 19 shows a front of haze moving southwestward along the Atlantic coast on
25 August 1976. This feature was tracked for 3 days and finally disappeared on 26
August, after being advected into a line of thunderstorms along the Florida peninsula,
where its aerosols presumably underwent washout.
The satellite data allow for rational extrapolation of surface visibility and sulfate
measurements, particularly over water, as well as provide a context for the analysis of
aircraft data. Tracking well-defined structural haze features provides a possible means
for verifying trajectory and transport models. The export of polluted air masses into,
and possibly across, the Atlantic can be studied. (The European METEORSAT satellite
provides a similar capability in the eastern Atlantic). Actual digital processing of the
SMS/GOES data allows for the testing of statistical and physical models relating
atmospheric turbidity, visual range, and sulfate aerosol content.
Real-time data access, processing, and display systems, such as Mel DAS, allow
the researcher to compile available satellite and meteorological information about
PEPE's in an easy to manipulate and evaluate form. The basic software can be aug-
mented by addition of pollution emission inventories, addition of forecasted boundary
layer winds and trajectories (from LFM model outputs of the National Meteorological
Center), and predictions of future pollution patterns available from existing regional
models. The ability of such systems to process and display these data in real-time
allows for a vastly improved system of monitoring synoptic scale pollution events—
and therefore is a valuable management tool for planning and directing field data
gathering projects. Also data and analysis needed for later research can be assembled
and error checked "on the fly," thus compiling a real-time climatology and limiting
costly data archival and retrieval costs.
ACKNOWLEDGMENTS
This research was primarily funded by the Regional Field Studies Office, U.S.
Environmental Protection Agency (Dr. William E. Wilson, Scientific Director), under
subcontract No. 68-02-3000, "Conduct Seminar/Workshop on Elevated Pollution
Episodes and Furnish Background Reports to Assist EPA Management in Planning
Future STATE Intensive Field Studies and Related Activities", to Research Triangle
Institute. The author also wishes to thank those individuals and organizations that
have contributed to this work: Professor Sagar Krupa (Department of Plant Pathology,
University of Minnesota); Mr. Perry Samson (N.Y. State Department of Environmental
Control); The Space Science Engineering Center of the University of Wisconsin; Dr.
Brand Nieman (Teknekron, Inc.); Dr. Rudolph Husar (Washington University); the
Walter A. Bohan Company; Frances Parmenter (NOAA/NESS); Dr. Glenn Hilst (EPRI);
Professor Kenneth Whitby (Department of Mechanical Engineering, University of
Minnesota); Dr. Roger L. Tanner (Brookhaven National Laboratory).
FIGURE -\9-Ponion of 2.0 km resolution visible image, 2230 GMT, 25 August 1976,
showing a front of turbid air moving south and west off the U.S. Atlantic Coast
204
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209
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STATUS REPORT ON PROJECT VISTTA
(Visibility Impairment Due to Sulfur Transport
and Transformation in the Atmosphere)
William E. Wilson, Jr., Ph.D.
Environmental Sciences Research Laboratory
U.S. Environmental Protection Agency
William £ Wilson. Jr
INTRODUCTION
BACKGROUND
The Clean Air Act Amendments of 1977, in Section 169A, state that "Congress
hereby declares as a national goal the prevention of any future, and the remedying
of any existing, impairment of visibility in mandatory Class 1 Federal areas which
impairment results from man-made air pollution." Project VISTTA was initiated by
EPA's Environmental Sciences Research Laboratory in response to this congressional
mandate. The first phase of VISTTA, conducted during FY 1977 and FY 1978,
emphasized studies of trends, sources, and characteristics of visibility reduction in
Western Pristine Areas, especially the four-state area including New Mexico, Arizona,
Colorado, and Utah. The second phase of VISTTA has as its primary objective the
evaluation of an existing plume blight model. Data for this purpose will be collected
in field studies planned for July and December of 1979. In the third phase of
VISTTA, planned for FY 1979, field data will be collected and used to evaluate a
regional model of visibility reduction. This paper will provide some background infor-
mation on visibility, report some results from VISTTA-Phase I, and describe plans
for VISTTA-Phase II.
The most obvious air pollution effect is visibility reduction. The human eye is,
in effect, the reference method for measuring visibility reduction. Visibility is also the
best understood of all air pollution effects. Visibility is reduced by light scattering by
small particles in the air, light absorption by particles, and light absorption by nitrogen
dioxide. Cause and effect have been clearly established, both theoretically and empir-
ically. Quantitative measurements have been made of the influence of pollutant para-
meters such as particle size and refractive index and environmental parameters such as
relative humidity and sun angle. Much of this information has been documented in
two recent publications—Visibility Protect/on for Class 1 Areas: The Technical Basis
(1) prepared for the Council on Environmental Quality (CEQ) by Robert Charlson and
colleagues at the University of Washington (Seattle, WA) and based on research
211
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PROJECT VISTTA
sponsered by EPA and its predecessor agencies over the past 20 years; and The Report
to Congress on Visibility (2) prepared by EPA's Office of Air Quality Planning and
Standards (OAQPS) based on contributions from scientists much of whose research was
also supported by EPA's Office of Research and Development. It is worth emphasizing
that the present understanding of visibility reduction is not due to a crash program
initiated when Congress passed Section 169A but is due to the fact that EPA's Office
of Research and Development, and its predecessor agencies, have funded over the last
20 years a modest but continuous fundamental research program on the physical,
chemical, and optical properties of aerosols. As a result of this work we understand
very well the interrelationships between pollutants and the visual quality of the air and
can plan effective control strategies.
The overall objective of VISTTA is the quantitative prediction of the effect of
sources, especially power plants, on visual air quality in Western Pristine Areas. The
objectives of VISTTA-Phase I are:
• To determine long-term trends in visual air quality in Western Pristine Areas and
to associate visibility reduction with specific pollutants.
• To characterize the visibility-reducing aerosol in Western Pristine Areas with
respect to particle size, chemical composition, and spatial distribution.
• To characterize the emissions from power plants, smelters and urban plumes,
sources which along with natural background are thought to be most important
in reducing visual air quality.
• To utilize information on the size and composition of ambient and source
emissions to estimate the contributions of the various sources to visibility
reduction.
VISUAL AIR QUALITY
TRENDS
Human observers with the National Weather Service make hourly measurements
of visibility distance at over 200 weather service stations across the United States.
Twenty-five years of such data have been analyzed to determine trends in visual air
quality. The trends in the more polluted eastern United States are clear and dra-
matic (3,4). Trends in the Western Pristine Areas, while not so obvious, still show a
general pattern of decreasing visibility from 1954 to 1971 followed by an improvement
between 1971 and 1975 (5,6). Historical visibility trends are shown in Figure 1 for
90(144)
80(128)
70(112)c
60(96)
J
J3 50(80)
e
>"
5 40(64)
CO
D5
* 30(48)
20(32)
10(16)
Ol—
1950
50THPERCENTILE
STATION MOVED (APPARENTLY NOT
SIGNIFICANT)
1955
1960 1965
TIME, year
1970
1975
FIGURE 1-Long term visibility trends at Tucson, Arizona, 1950-76
212
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140 -,
120-
j| 100-
1
t 80-
w
> 60-
40 -
20 -
10th Percentile (Estimated)
50th Percentile
90th Percentile
48 50
i
55
T
60
65
i
70
I I
75 76
YEAR
FIGURE 2—Long-term visibility trends at Cheyenne, Wyoming
Tucson, Arizona, an urban site, and Figure 2 for Cheyenne, Wyoming, a nonurban site.
In Tucson, median visibility distance dropped from near 70 miles in the 1950's to 55
miles in the years around 1970 followed by an improvement to nearly 65 miles by
1976. The median visibility distance in Cheyenne dropped from the neighborhood of
80 miles in the early 1960's to 50 miles by 1974 followed by an improvement to 70
miles by 1970. In Table 1 changes in the 3-year averages of median visibility distances
for 1970 to 1972 and 1974 to 1976 are shown for the 12 sites for which adequate
visibility measurements are available. For the Arizona, Nevada, and Utah sites, the
TABLE 1
Changes in three-year averages of median visibility distances
1954-71
1971-75
URBAN
Phoenix, Airzona
Tucson, Arizona
Denver, Colorado
Salt Lake City, Utah
NON-URBAN
Prescott, Arizona
Grand Junction, Colorado
Ely, Nebraska
Cheyenne, Wyoming
-23
-22
-13
-22
-25
- 4
-42
-23
+ 12
+ 12
+ 7
0
+ 7
+ 3
+ 18
+ 12
213
-------
improvements in visibility from 1974 to 1976 are thought to be due to decrease in
SC>2 emissions from smelters. Reasonable correlations have been obtained between
SC>2 emissions and visibility distances (6). Regression analyses for Western Pristine
Areas indicate that the mass of sulfate, nitrate, and remaining total suspended particu-
late matter are all required to obtain good correlations between visibility distance and
pollutant concentrations (5).
AEROSOL CHARACTERIZATIO'j
The extinction of light caused by particles is due partly to absorption and partly
to scatter. Absorption is not a strong function of particle size, but as shown in Figure
3 scattering does depend strongly on the size of the particle. The scattering peaks
between 0.2 and 1.0 micron diameter, which is also the size at which the mass concen-
tration of fine particles peaks. A particle distribution measured in Phoenix (7) and the
calculated light scattering are shown in Figure 4. Even though the coarse particle
10
E
a.
10-2
10'1 2 5
PARTICLE DIAMETER, Mm
10"
FIGURE ^-Scattering and absorption coefficients per unit volume as a function of particle
size; nj = 1.5, n2 = 0.05 at 550 nm
10-2 2
5 10'1
102 2
5 10" 2
DIAMETER, /jm
FIGURE 4-Size distribution and light scattering from an urban aerosol, Phoenix, Arizona
214
-------
concentration is many times that of the fine particles, coarse particles are responsible
for only a small part of the light scattering. Rural measurements such as are shown in
Figure 5 have a much smaller concentration of coarse particles, and a correspondingly
greater portion of the light scattering is due to the fine particles. Light scattering as a
function of size for a rural aerosol measured during a regional flight is shown in
Figure 6 (8).
16
14
12
10
~x. 8
BRYCE CANYON 1978
12
10
16
10-2 2 5 10-1 2
100 2
DIAMETER,
101
FIGURE 5—Size distribution and light scattering from a non-urban aerosol,
Bryce Canyon, Colorado
30
20
10
LIGHT SCATTERING CONTRIBUTION
ASA FUNCTION OF SIZE,
SOUTHWEST REGION
0.05
0.1
0.2
0.3
0.5
1
10
PARTICLE DIAMETER, pm
FIGURE 6—Light scattering as a function of size for average aerosol size distribution
measured during a regional flight
215
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AEROSOL COMPOSITION
CHEMICAL ELEMENT
BALANCE
The composition of the coarse and fine aerosol fractions from a regional flight
is shown in Figures 7 and 8. Crustal material, SiO2, AI2O3, CaO, and Fe2O3, make
up a majority of the mass of the coarse particles. For the fine particles sulfate and
silica (SiO2> are the major species with carbon (soot and organic aerosols) and other
species making appreciable contributions. Of special interest is the large amount of
silica in the fine particle fraction. Substantial amounts of fine particle silica were
found in regional aerosols and in smelter plumes, with somewhat lesser amounts in
power plant plumes. The fine particle silica appears to be due to condensation of
vapor rather than being a tail of the coarse particle size distribution and may be
generated during the combustion process. Fine particle silica has been observed by
other investigators using the electron microscope but has not previously been
attributed to anthropogenic sources (9). The possible existence of fine particle silica in
emissions from combustion sources needs to be confirmed by other measurements and
analytical techniques. However, if confirmed, this would affect control strategy since
fine particle silica might not be effectively removed by scrubbers installed to reduce
S02 emissions.
There are two basic techniques for inferring the contribution of various sources
to the atmospheric loading of particles and the resulting visibility reduction. One is
predictive modeling, which can apply to any specific source, existing or planned.
The other involves inferring the source from a knowledge of the composition of
particles emitted by a variety of sources and the characteristics of the ambient aerosol.
As originally developed by Professor Friedlander it is known as the Chemical Element
Balance Technique (10). It can be augmented by information on chemical compounds
and particle shape determined by microscopy. When the composition of source
emissions is unknown, sources may sometimes be inferred by a statistical technique,
factor analysis, which can ascertain which elements vary together and may therefore
come from a specific source or source type.
COARSE PARTICLES
MASS = 4.0 /ug/nr
FINE PARTICLES
MASS -- 6.
FIGURE 7—Composition of coarse particles collected
during a regional flight
FIGURE 8—Composition of fine particles measured-
during a regional flight
216
-------
It is hoped that the composition and size data obtained in the VISTTA study
may be used to determine the relative contributions of what are thought to be the
major sources: power plants, smelters, urban plumes, and background. This pro-
cedure is shown schematically in Figure 9. The major problem areas in applying this
technique are inadequate knowledge of smelter and background aerosols and differ-
entiating the various sources of soil-like material. Microscopy can be used to differ-
entiate fly ash, urban road dust, and wind-blown desert dust, but this is slow, expen-
sive, and not very quantitative.
Aerosol Size and Composition
Sources
Ambient
Chemical Element Balance
Factor Analysis
Microscropy
Power Plants
Urban Plumes
Smelters
Background
Visual Air Quality
FIGURE 9-Source apportionment
PREDICTIVE MODELS
Predictive models provide another technique for determining the contribution
of an existing source to existing visibility reduction. They have the added advantage
that they can predict the effect of a projected new source. However, their accuracy
cannot be estimated without sensitivity studies and validation by comparison of field
measurements with predictions. The components of a visibility model are shown in
Figure 10. One asterisk means the process or parameter is fairly well understood, two
asterisks mean we have some knowledge and some needed studies are underway,
three asterisks mean we do not understand the process and do not have adequate
research programs to address the problem.
Ongoing work on modeling has led to reasonable understanding of transport
and dispersion over smooth terrain. However, transport and dispersion in the complex
terrain frequently characteristic of Western Pristine Areas is not well understood.
The gas-phase reactions, which convert NO to N02 to nitric acid and S02 to sulfate,
are fairly well understood from laboratory, smog chamber, and field studies. How-
ever, the conversion processes involving gas-aerosol systems such as may occur in
clouds are not understood but may be important. There is some information on
the dry deposition of gases onto eastern United States type vegetation but inadequate
information on dry deposition of particles and dry deposition of gases onto western
vegetation and surfaces.
217
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Emissions*
Transmission
Transport**
Transformations
Photochemical Smog*
Gas-Aerosol***
Aerosol Dynamics
Coagulation*
Condensation*
Growth Laws*
Dispersion***
Removal
Dry Deposition*
Wet Removal**
Aerosol Size and Chemical Composition
Aerosol Optical Properties*
Visual Air Quality*
FIGURE ^-Predictive models
VISTTA-I RESULTS
Once formation and removal rates are known, aerosol dynamic models should
give an adequate estimation of the resulting aerosol size distribution concentration
and composition. However, evaluation of the models with field data needs to be
done and simplified versions of the aerosol dynamics need to be developed for use
in predictive models. The calculation of optical properties (absorption and scatter-
ing) is straightforward for ideal, spherical particles. However, work is needed to
determine the significance of errors due to nonideality of real particles.
One additional model module is required for a visibility model. A module
is needed which uses extinction (scatter + absorption) of particles and absorption of
N02 to calculate the effect of regional haze or an individual plume on the contrast,
color and other optical properties that make up visual air quality. One such module
has been developed for Office of Air Quality Planning and Standards by Systems
Applications, Inc., for the single plume situation (plume blight model). The primary
objective of VISTTA-I I is to obtain plume data and use the data to evaluate and
improve this model.
A detailed account of the results from VISTTA-I is given in two MR I reports
(8,11) and a paper presented at the New York Academy of Sciences (12). Results from
the first VISTTA field study are summarized below:
• On two regional flights over large parts of the Southwest, the visibility-reducing
aerosol was quite homogeneous throughout the entire region, indicating that the
visibility impairment was of regional character.
• The aerosol size distribution throughout the region on October 5 and 9, 1977,
was bimodal, with a geometric volume mean size for the fine particles of ~0.25
micron, which is slightly smaller than the continental background aerosol average
mean size (0.3 micron). The measured coarse particle mode velumetric mean
size was ~5.5 microns, which is equal, within error, to the continental
background.
218
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REGIONAL AND PLUME
IMPACTOR SAMPLES
PARTICLE SOURCES
VISTTA-M PLANS
• The elemental size distribution from both regional and plume impactor samples
indicated that aluminum, calcium, and iron are present predominantly in coarse
particles; sulfur and titanium are present predominantly in fine particles; and
silicon and potassium have substantial concentrations in both modes.
• Sulfur and silicon were found in nearly equal concentrations in the Southwest
background data and were the elements present in the highest concentrations
in the fine particles (Dp<1^m), The detailed aerosol mass balance determined for
the Southwest region showed that sulfur (expressed as ammonium sulfate) and
silicon (expressed as SiO2) amounted to ~53 percent and ~29 percent of the
fine particle mass, respectively.
• A total of ~93 percent of the measured coarse particle (D >1 ^m) mass in
the Southwest region was composed of elements which were present in the
same abundances relative to aluminum as in the earth's crust. This indicates
that the source of these particles is either wind-blown dust or material with
an elemental composition nearly that of crustal material, such as fly ash.
• The light-scattering budget for Southwest background aerosol on October 9,
1977, indicated that ~52 percent of the light scattering was due to fine particles,
~44 percent was due to Rayleigh scattering from gases, and ~4 percent was due
to coarse particles. Considering only the light scattering due to particles, ~3
percent is due to fine particles, which are composed mainly of sulfates [~53
percent as (NH4)2SO4l and silicon compounds (~29 percent as SiO2).
• Mie scattering calculations of light-scattering coefficient due to particles using
the measured average regional size distribution were in good agreement with
the values measured with a nephelometer. This is a quantitative indication of
the internal consistency of the size distribution and bscat measurements which
adds credibility to the calculated light-scattering budget.
• Plume excess fine particle aerosol, i.e., the point source emission plume aerosol
with the background substracted, was composed largely of sulfur and silicon
compounds for both the smelter and power plant plumes. The major elemental
species in the plume excess coarse particle aerosol were aluminum, silicon,
potassium, calcium, and iron in approximately crustal abundances in both
plumes. These results indicate that fine particle silica may be a good tracer
for primary combustion aerosol in smelter and power plant plumes.
• A simple semiquantitative calculation of visual plume impact was performed to
determine the visual range with and without the plume present. For the October
4, 1977, flight, the smelter plume caused ~90 percent reduction of visual range
relative to the background visual range (135 km) at 8 km downwind from the
plant. As far as 127 km downwind, increased bscat and sulfate levels relative to
background concentrations were observed, and ~12 percent reduction of visual
range due to the smelter plume was calculated. Measurements in the Mohave
power plant plume showed ~25 percent reduction of visual range at 60 km
downwind on October 8, 1977.
• Sulfate aerosol was formed in Southwest power plant and smelter plumes. The
measured S02 conversion rate from the San Manuel copper smelter on one
morning between 0900 and 1230 (MST) was 0.7±0.2 percent/hour between 60
and 127 km downwind.
• The plume excess visibility budget indicated that fine particle sulfur and silicon
species contribute ~53 percent to the excess bsca^ in the San Manuel smelter
plume. In the Mohave power plant plume, coarse particles were the major
contributors to the excess bscat, which may have been at least partially due to
wind-blown dust on the sampling day.
VISTTA-II will continue the characterization and source apportionment efforts
begun in VISTTA-I but will emphasize field measurements to evaluate a plume blight
model developed for OAQPS by SAI. The field studies will involve extensive
measurements of the optical properties of the plume. Aerosol concentration and size
219
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VISTTA-III
distribution, light scattering and absorption, and contrast measurements by tele-
photometer will be made for 3 weeks during June and July and 2 weeks during
December 1979. During the December study, photographs will be taken to use in a
human perception study.
VISTTA-III, which will begin in FY 1981, will emphasize regional visibility
reduction and will gather field data to evaluate a number of regional field models.
As a result of fundamental research conducted over the last 20 years we have
a good understanding of the interrelationships of pollutants and visual air quality.
However, a substantial amount of research remains to be done before we can accu-
rately predict the impact of a single source on visual air quality.
ACKNOWLEDGMENTS
VISTTA-!
VISTTA-II
Project VISTTA is a team project directed by the Regional Field Studies Office
of EPA's Environmental Sciences Research Laboratory. The groups involved in
VISTTA-I and their responsibilities are:
• Meteorology Research, Inc. (MRI)-Project planning, design, and coordination,
aircraft sampling, and data analysis
• Aerosol Research Branch, ESRL, EPA—Quality assurance of aircraft measure-
ments
• University of California Davis (UCD)—Elemental analysis of samples from a
specially designed UCD airborne impactor
» University of Washington (UW)—Ground-based measurements of size distribu-
tion, light scattering, and light absorption coefficients
• California Institute of Technology (CIT)—Data analysis
The following individuals contributed to this program:
Project Coordinator, D.L. Blumenthal (MR)
Senior Data Analyst, E.S. Macias (CIT, Consultant to MR I on leave from
Washington University, St. Louis):
Field Manager, J.A. Anderson (MRI)
Data Analysis, B.K. Cantrell (SRI International)
Data Analysis, S.K. Friedlander (UCLA)
Data Analysis, J.A. Ogren (MRI and UW)
Impactor Design and Sample Analysis, D.L. Shadoan, T. Chaill (UCD)
Sulfate Analysis, J.D. Husar and Associates
Tom Ellestad, EPA, assisted in the planning of the program and served as project
officer for the University of Washington grant.
The scientific team has been much expanded for VISTTA-II. Those partici-
pating in program planning will be listed here. Dave McNeils, Bob Snelling, and Bill
Malm from EPA's Environmental Monitoring and Support Laboratory in Las Vegas
have contributed to planning and field activities. The plume blight model being
evaluated was developed by Systems Applications, Inc. (SAI) for OAQPS. Steve
Eigsti is the EPA project officer. Shepherd Burton, Bob Bergstrom, and David Latimer
of SAI are involved in planning the field program and evaluating the model. Personnel
from the Salt River Project, operators of the Navajo Power Plant, under the direction
of Leroy Michael, Jr., and Prem Bhardwaja, are participating in the study. Will
Richards of MRI is field manager for VISTTA-II.
220
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References
1. Charlson, R.J., A.P. Waggoner, and S.F Thielke. "Visibility Protection for Class I
Areas: The Technical Basis." Report to the Council on Environmental Quality
(NTIS No. PB-288-842), 1978.
2. "Protecting Visibility: An EPA Report to Congress." Draft, Sept. 1979. EPA-
450/5-79-008, Office of Air Quality Planning and Standards.
3. Trijonis, J. "Visibility in the Northeast: Long Term Visibility Trends and
Visibility/Pollutant Relationships." Grant No. 803896, EPA-600/3-78-075,
August 1978.
4. Husar, R.B., D.E. Patterson, J.M. Holloway, W.E. Wilson, and T. Ellestad.
"Trends in Eastern U.S. Haziness Since 1948." Volume for Symposium on
Turbulence, Diffusion, and Air Pollution, Jan. 15-18, 1979, Reno, Nevada.
5. Trijonis, J. "Visibility in the Southeast: An Exploration of the Historical Data
Base." Grant No. 803896, EPA-600/3-78-039, April 1978.
6. Marians, M., and J. Trijonis. "Empirical Studies of the Relationship Between
Emissions and Visibility in the Southeast." Grant 802015.
7. Private Communication, Alan Waggoner, University of Washington, Seattle,
Washington.
8. Blumenthal, D.L. "Characterization of Visibility-Reducing Aerosols in the South-
western United States: Interim Report on Project VISTTA." 68-02-2713, MRI,
January 1979.
9. Allee, P.A., R.F. Pueschel and W.W. Wagner. "On the Co-Existence of Natural
and Man Made Aerosols in a Rural Environment." American Chemical Society,
1978.
10. Friedlander, S.K. "Srnoke, Dust and Haze." Chapter II. Air Quality Emission
Source Relationships, 1977, pp. 295-306.
11. Blumenthal, D.L. "Characterization of Visibility-Reducing Aersols in the South-
western United States: Interim Report on Project VISTTA, No. 2." To be
published.
12. Macias, E.S., and B.K. Cantrell. "Size and Composition of Visibility-Reducing
Aerosols in Southwestern Plumes." Prepared for presentation at the Conference
on Aerosols: Anthropogenic and Natural—Sources and Transport, New York
Academy of Sciences, January 9-12, 1979.
221
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ENVIRONMENTAL EFFECTS OF ACID PRECIPITATION
Norman R. Glass, Ph.D.
Gary E. Glass, Ph.D.
Environmental Research Laboratory
U.S. Environmental Protection Agency
Peter J. Rennie, Ph.D.
Canadian Forestry Service
Environment Canada
Norman R Glass Ph D
ADVERSE EFFECTS
DROP IN pH
Recent reviews of available data (1,2,3) indicate that precipitation in a large
region of North America is highly acidic when compared with the expected pH value
of 5.65 for pure rain water in equilibrium with CC>2 (4,5). It has also been shown (6)
that the time course of change in pH of precipitation from the mid-1950's to the
mid-1970's in the northeastern United States and Canada has been dramatic. Acid
precipitation has also spread measurably southward and westward in the United States
(1,6). More recent information indicates that, in the southern and western United
States, pH values between 3.0 and 4.0 are observed during individual storms (3).
Although prior to 1955 the record on changes in acidity of precipitation is very sparse,
there are data which indicate that by the mid-1950's precipitation in the eastern
United States was already acidic, and that the acidity of rain and snow in that region
increased significantly sometime between 1930 and 1950.
A growing amount of evidence suggests that acid rain is responsible for
substantial adverse effects on the public welfare. Such effects include the acidification
of lakes and rivers with resultant damage to fish and other components of aquatic
ecosystems, acidification and demineralization of soils, possible reductions in crop and
forest productivity, and deterioration of manmade materials (7,8,9). These effects can
be cumulative or can result from peak acidity episodes (10).
A drop in the pH of precipitation has been observed for many years in
Scandinavia (11). A monitoring network there has shown that, since the mid-1950's,
precipitation in northwestern Europe has increased in acidity and that this acidity is
currently widespread geographically. The hydrogen ion concentration of precipitation
in some parts of Scandinavia has increased more than 200 fold during the past two
decades (12).
223
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SOURCES OF ACID RAIN
URBAN PLUME
WET DEPOSITION
Data from New York state and parts of New England indicate that
approximately 60% to 70% of the acidity is due to sulfuric acid, and 30% to 40% of
the acidity is due to nitric acid. These strong acids are thought to stem primarily from
gaseous manmade pollutants such as sulfur oxides and nitrogen oxides produced
primarily, although not exclusively, from the combustion of fossil fuels. The relative
proportion of nitric acid derivatives and sulfuric acid derivatives may be an adequate
indication of the source from which the acid rain was derived; a high proportion of
oxides of nitrogen or of nitric acid derivatives would indicate automobile or mobile
sources, whereas a high proportion of sulfuric acid derivatives would indicate stationary
sources such as power plants, smelters and heavy industry. It is interesting to note that
in England in the early part of this century the acidity in the vicinity of Leeds (a
heavy coal-use region) was approximately 75% attributable to sulfur compounds
(13), and pH in rain and fog appears to have dropped below 3.0 on occasion.
Emission sources for sulfur oxides and nitrogen oxides are widely distributed
within and outside urban centers. Contributions can come from stacks, both high and
low, and from near ground level sources. Sulfates, including acid sulfates, are present in
the stack gases associated with coal-fired and oil-fired sources. The amounts of sulfuric
acid and other sulfates found in plumes can be sufficient to affect plume opacity and
fallout of acid particles near the source. In plumes from elevated sources, lack of
contact with the ground tends to preserve precursors for some distance downwind. At
night and in the early morning especially, ground-based inversions can isolate the
plume aloft so that near-source deposition is minimized (14).
The urban plume already contains organics, sulfur oxides and nitrogen oxide
precursors to sulfates and nitrates (15). Photochemical atmospheric reactions can form
sulfates and nitrates relatively rapidly as the urban plume progresses downwind.
However, during periods of effective photochemical activity urban plumes will tend to
be well mixed all the way to the ground. Therefore, dry deposition processes are
competing with atmospheric reactions as sinks for sulfur oxides and nitrogen oxides
(14).
In this country, acid precipitation is thought to be most severe in the northeast.
Recent data, however, show the problem to be increasing in the southeast and midwest
with all states east of the Mississippi affected to some degree. Furthermore, there is
recent evidence of acid rain in the western United States, at least in major urban
centers such as the Los Angeles area, San Francisco and Seattle (16,17). The ratio of
sulfur derivatives to nitrogen derivates (approx. 2) indicates that acidity in and near
urban areas of the west is probably due to automobiles rather than to stationary
sources. Precipitation analyses show that the acid rain problem extends into Canada,
covering an extensive eastern area as well as a western Alberta region. Unlike more
conventional atmospheric pollution, that which gives rise to acid rain may not exceed
air quality standards nor cause immediately obvious damage to receptor organisms and
materials.
In Canada emissions of SO2 amount to about 6.5 x 10^ metric tons annually,
causing concern in three main areas and several smaller ones. The major areas are the
Sudbury region of Ontario (13.7 x 10^ km2), the Windsor-Sudbury-Montreal triangle
in Ontario and Quebec (150 x lO^krr^), and the Grande Prairie-Edmonton-Pincher
Creek triangle in southwestern Alberta (78 x 10^ km2). The isolated centers include
Noranda, Quebec; Thompson, Manitoba; Murdochville, Quebec; and Flin Flon,
Manitoba. In Sudbury, high ambient concentrations of SO2, acting with acid rain and
particulates have for many years been a major threat to vegetation and other
environmental values. In the Windsor-Sudbury-Montreal triangle, local emissions have
not by themselves generated problems, but steady urban-industrial expansion,
combined with large emissions in surrounding areas, has caused the normal resilience of
environmental characteristics, particularly water bodies, to be exceeded. In
southwestern Alberta, emissions from sour-gas processing do not yet constitute a
serious threat, but some of the region's agricultural crops are highly sensitive (18).
From the Canadian precipitation sampling and analysis network (CANSAP), data
show that large parts of eastern Ontario, stretching from the Manitoba-Ontario border
to Newfoundland, receive substantial amounts of SO4 in the form of wet deposition
224
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BEDROCK GEOLOGY
LAKE SENSITIVITY
(19). In the more markedly affected parts of southcentral Ontario and Quebec, the
amounts of 804 being deposited range from 0.6 grams to 2.6 grams of S per m2 per
year. Such deposition rates are less than those in the more severely affected parts of
the northeastern United States, but they are about the same as those recorded in
Scandinavia where serious damage to the environment has occurred (20).
Serious though these emission and deposition data appear, they become
significant only when the nature and properties of the impacted materials are also
taken into account. For this reason, precipitation would have to become very acid
indeed in the Canadian Prairies to generate environmental concern for calcareous or
sulfur deficient soils (21). The same holds for the calcareous and neutral soils of
southern Ontario in spite of appreciable sulfate loadings. However, for most of eastern
Canada, soils are podzolic, are not well endowed with nutrient elements, and display
natural acidities ranging from about pH 4 in the surface horizons to about 5.5 in the
lower parts of the profile (22).
In general, then, the picture for much of eastern Canada is of a bedrock geology
with surficial deposits giving rise to acidic soils and water bodies that are naturally
low in alkalinity and calcium reserves. Their neutralizing ability is limited and their
resistance to further acidification is severely tested when the strongly dissociated
sulfuric acid brought in by acid rain supplants a system normally stabilized by the far
less strongly dissociated carbonic and other organic acids.
However, such terrestrial and aquatic systems must not be thought of as being
unproductive and of little ecological or economic significance. For the forest resource
alone, for example, the direct value (after processing) is about $4 billion per year;
indirect and intangible values in providing recreation, providing habitat for wildlife,
stabilizing river flow, preventing erosion and the siltation of water bodies, and
furnishing aesthetic appeal are inestimable. Forest growth rates are not as high as
in other more favored soil and climatic zones of North America, but this merely means
that larger areas have to be more soundly managed than elsewhere.
As the United States increasingly relies on coal as an energy source because of
crude oil price and foreign crude oil supply problems, as well as the questionable
safety of nuclear power, air emissions from energy producers will increase. Switching
fuel from natural gas or oil to coal will make the task of reducing sulfur emissions
from new and existing power plants difficult. Mobile and stationary sources of NOX
will also continue to contribute to the loading of acidity to the aquatic and terrestrial
environment. In brief, it seems probable that acid deposition to the environment will
at least remain at present levels and might be expected to increase over the next
decade or two.
As more coal-fired power plants are built and become operational, expecially
upwind of the westcentral United States and in the midwest and southeast, the thres-
hold of lake acidification may be exceeded. The threshold value for Swedish lakes is an
annual average pH depressed to pH 4.6 or below (23). Increased acid loading beyond
the threshold value has resulted in more than 15,000 fishless lakes in Sweden.
The transferability of this threshold value for U.S. watersheds (lakes) will depend
on the similarity of the environmental factors of the watersheds, and primarily on the
lack of acid neutralizing (or alkaline) soils. This single primary factor places limits
on the geographic regions which are extremely sensitive to acid precipitation. Lakes
in the Adirondack State Park of New York and the Boundary Waters Canoe Area—
Voyageurs National Park (BWCA-VNP) of Minnesota are examples of such susceptible
environments in the U.S. In the Adirondack area the threshold acid precipitation
value has been exceeded for many years and as a result, lake pH values are depressed
to the point where fish have stopped reproducing and some 90 lakes are now fishless
(24).
MAXIMUM SENSITIVITY
In the BWCA-VNP, the process of lake acidification is just beginning and only
the most susceptible lakes are affected. This area is one that exhibits the proper-
ties of maximum sensitivity to acidification due to extremely soft waters, thin soils
and very sensitive terrestrial and aquatic plants and animals. In addition, the BWCA is
225
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ACIDIC BEDROCK
EXHAUSTED
BUFFER CAPACITY
EFFECTS ON SOILS
AND FORESTS
a wilderness area where the Congress has taken extreme care to preserve the environ-
ment against the impacts of development (P.L. 95-495). No man-induced changes
are desired. As a wilderness area it is also a class I air quality maintenance area under
the Clean Air Act.
The BWCA-VNP region like the Adirondack Park area is found on acidic bedrock
which is the main criterion for an acid-sensitive classification (25). Of the midwestern
states, only upper Michigan, northern Wisconsin, and northern Minnesota have this
type of bedrock covering wide areas (25). The lakes in the BWCA-VNP area have only
been surveyed recently for possible impacts from acid precipitation (26) and the results
are shown in Figure 1. About two-thirds of the 85 lakes sampled in 1978 and 1979 are
susceptible to change from acid precipitation. If these lakes are representative of the
1,500 lakes in the BWCA-VNP, the potential for severe ecological damage is serious.
The annual average pH of precipitation in this region is just at the edge of 4.6, and
contributions from increasing emissions, including six major coal-fired power plants
that are being built or just completed in the area, will certainly increase the rate of
acidification.
Another measure of the acidification process is shown in Figure 2. Since the
major source of acid in precipitation is related to sulfur emissions, the extent of lake
acidification has been measured as a function of annual atmospheric loadings of sulfate
for lakes in southern Sweden. The sharp drop of this pH curve for extremely sensitive
lakes shows how a slow increase in added increments can and will cause a sharp break
in the response curve. This response is characteristic of very soft water lakes where
only a small amount of bicarbonate is available to neutralize the incoming acid. The
pH remains relatively constant until all of the carbonate is consumed and then the
stronger organic and sulfuric acids control the lake pH. In other words the assimilative
capacity (or buffer capacity) of the lake has been exhausted as indicated by the break
point and downward slope, especially, on curve 1 of Figure 2.
The general shape of the sulfate loading-pH response curve shown in Figure 2 is
also expected for an individual lake as the acid loading from atmospheric sources is
increased over time. For a given region where the loading is fairly constant, the pH
response of lakes may be described as a series of response curves, similar to those in
Figure 2, each reflecting individual differences and characteristics of the particular lake
watershed. Some of the factors which control the shape and displacement of these
loading-pH responses are watershed area/lake volume ratio, soil-geology factors, vegeta-
tive cover, ground water input, organic acid input from bogs, and a host of other
factors yet to be defined. The size of watershed and stream order have also recently
been discussed as factors in pH loading (27). If the acid loading to a particular region
is limited to the amounts defined by the upper portions of the response curves for
sensitive lake systems, the magnitude of the damage to the aquatic environment can be
minimized.
In 1930, the federal Canadian Forestry Service became involved in terrestrial
research on air pollution effects dealing with problems at Trail, British Columbia, and
with the separation of pollution effects on forests from those arising from insect and
disease attack. Since then numerous signal contributions have been added to the
understanding of pollution problems, usually near strong point emitters (28,29,30,31,
32,33). In perspective, although there may seem to be many features common to
acid rain and atmospheric pollution regardless of how they originate, there are two
important differences. First, long-range pollution usually does not exceed conventional
air quality standards. Second, it may not cause any spectacular or immediately measur-
able reduction in tree growth. A superficial view, therefore, or one based on a ranking
in priority of more obvious disasters would fail to discern much of a problem. Early
research of H. J. Wheeler in Rhode Island and J. A. Voelcker at Woburn may now
seem very distant, but their striking demonstration of the soil acidification, calcium
removal, and aluminum solubilization effects consequent upon repeated sulfate fertil-
izer applications are well documented (34). Indeed, the apprehension is that acid rain
could bring about analogous effects leading to permanent reduction in tree growth and
site quality. Useful soil microorganisms will be eliminated and potentially toxic soil
elements, such as aluminum and manganese, brought into solution to exercise delete-
rious effects on plant roots and nutrient absorption. Moreover, since heavy metal
226
-------
8.0
7.5
7.0
pH 6.5
6.0
5.5
5.0
1500
1000
NOT SUSCEPTIBLE
500
—i—
BWCA-VNP LAKES
SUSCEPTIBLE
(KRAMER
* 1976)
POTENTIALLY.
SUSCEPTIBLE ......
FISHERY:
MEAN DANGER
P" THRESHOLD
8.0
7.5
7.0
1500
1000
ALKALINITY
500
6.5 pH
6.0
5.5
5.0
FIGURE t-The relationship between pH and alkalinity in 85 BWCA-VNP lakes
pH
I
0 30 60 90
SULFATE LOADING TO LAKE WATER (Kg/ha/yr)
FIGURE 2—Data from lakes in Sweden showing the relationship between acid loading and
pH change for (1) very sensitive and (2) somewhat less sensitive surroundings
227
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NEW APPROACHES
EFFECTS ON
AGRICULTURAL SYSTEMS
ALTERATIONS IN
PATHOGENICITY
particulates sometimes accompany gaseous pollutants, a situation could arise that such
noxious elements are held preferentially on the exchange sites of colloids at the
expense of the more useful monovalent and divalent cations.
Unlike the situation in aquatic systems, however, there is a more acid state of
podzolic forest soils, where acid rain may not very readily lower the pH further or
induce further losses in bases (35). The complex makeup of soils prevents the pinpoint-
ing of a sharply critical soil pH value separating adverse and nonadverse effects of acid
rain. However, it seems likely that the approximate value lies within the pH 4.0-5.5
gradient seen in eastern Canada podzol profiles.
New approaches, not based on strong point emitters, include sensitivity mapping.
This can be very crude—such as the separation of areas of calcarious and noncalcarious
bedrock or the identification of sulfur deficient soils (21)-or it can be large-scale
and based on a synthesis of soil attributes. Considerable progress has been made in
grading the sensitivity of Ontario lakes, using alkalinity as an index, and it is possible
that a somewhat similar index based on exchangeable calcium status could be used
for soils. For at least the reasons that are explained above, however, such a soil sensi-
tivity index may always be no more than a very crude indicator.
Of particular value are lysimetric-type studies in progress by I. K. Morrison and
his colleagues at Sault Ste. Marie, Michigan. Representative monoliths are being per-
colated, with known amounts of simulated rain, to test the rate at which horizons
change their properties and the speed of calcium release. Knowing the sulfate loadings
such soils are experiencing under natural conditions, the results from such lysimetric
installations should permit approximate predictions of soil changes under field
conditions.
There are two basic ways acidic precipitation can impact agricultural crops. First,
acidic precipitation can impact directly on the foliar surface of the plant itself causing
a direct effect on the leaf or stem of the crop plant. In these cases the most immediate
effect is on crops such as lettuce, spinach, or chard for which the foliage is the
valuable portion. Second, acidic precipitation can indirectly affect the crop plant
through effects on the soil. For example, changing the pH of rainfall which strikes the
soil can change the rate at which nutrients are recycled, litter and other organic matter
is broken down through microbial action in the soil, and the rate at which both
macronutrients and micronutrients are leached from the soil into surface waters or into
ground waters. Detailed physiological mechanisms whereby these two basic impacts are
manifest have been discussed elsewhere (36).
At pH below about 3.0, areas of leaf surfaces generally become spotted or
necrotic. For obvious reasons, vegetables as well as ornamental plants may be un-
marketable after exposure to rain or mist at or near pH 3. With decreases in function-
ing leaf area, the photosynthetic process itself decreases and the productivity of the
plant necessarily decreases. It is also true that, with changes in aboveground biomass
such as would be experienced under low pH rain, belowground biomass would be
similarly decreased. It is not yet known what the relationship is between percent
leaf area affected (nonfunctional due to necrotic areas) and percent change in growth
for plants. However, it is known that, with depressed pH, foliar losses of important
nutrients such as K+, Mg++, and Ca++ are observed (37,38).
Nutrient cycling changes in either agricultural land or forestry land can result in
lowered fertility over the long term as well as decreases in essential soil nutrients which
are required for normal plant growth.
In three out of five host-parasite systems involving oak trees and kidney beans,
alterations occurred in the pathogenicity of the parasite under conditions of artificial
sulfuric acid precipitation at pH 3.2. An additional observation was that root nodule
number and nitrogen fixation of kidney bean were diminished by sulfuric acid rain
at pH 3.2, and that bean yield was decreased in low cation exchange capacity soils but
not decreased in higher cation exchange capacity (greater than 3 meq/100 g soil) soils
(39).
228
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EXTENSIVE SCREEN
PROGRAM
SUMMARY
Rain water at approximately pH 4.0 due to volcanic activity in the Kona district
of Hawaii is known to adversely affect tomatoes. While 5 kg per plant of salable fruit
was obtained from tomato plants grown under a plastic rain shelter, no salable fruit
was produced on plants growing immediately outside the rain shelter (40). While it is
possible that gaseous pollutants such as SC>2 may also be present near fumaroles or
volcanic activity, the fact that the plastic rain shelter provided enough protection to
the plants to permit fruiting indicates that gases alone are probably not the cause. It is
possible that the causative agent was not rainfall, but dry fallout. This possibility
should be investigated experimentally. However, it has been shown that cations, plant
growth regulating substances, and other materials are leached from growing plants by
rainfall (41) and that leaching rates increase for many materials as pH decreases (42).
While the data relating the effects of acid precipitation on crop yield and pro-
duction are somewhat sparse, there is every indication that acid rainfall is deleterious.
In order to pursue this hypothesis somewhat further, an extensive screening program to
look at the effect of sulfuric acid rain on virtually every major field crop of the United
States has been initiated by EPA. This study has been undertaken to determine the
sensitivity of crops to simulated acid precipitation in an experimental farm facility
because of the potential for widespread economic damage to a number of field crops
(43). Results from this study are expected by the summer of 1980. Preliminary indica-
tions of effect of simulated acid rain on yield of certain early maturing crop varieties
such as peas, broccoli, and certain other early crops are expected by fall, 1979.
In summary, there is substantial reason to suspect that the deposition of acidic
precipitation throughout wide geographic areas of the eastern United States and
Canada will have adverse effects on aquatic systems, forests, and agricultural systems.
Evidence presented in this paper suggests several avenues of research which should be
pursued to further define the magnitude and extent of the effects of acid precipitation
on resources. The cumulative threat of acid precipitation is recognized and a concerted
attack is being spearheaded by Environment Canada and the U.S. Environmental
Protection Agency that brings together different disciplines and jurisdictions. Ongoing
pollution studies based on strong point emitters and special new investigations are
being applied in a number of promising approaches. These include the use of sensitive
lichens as indicator species, previsual biochemical tests on tree tissues, differential
depositional patterns of pollutants on soils, and delineation of sensitive soils, forests,
and water bodies. While direct effects on terrestrial and aquatic ecosystems should be
investigated intensively, indirect effects on the abiotic components of such systems
should also be studied. For instance, a number of processes involving the impact of
acidic precipitation on soil systems, both amended agricultural soils and natural forest
soil systems, need to be investigated. Processes such as litter decomposition, nutrient
cycling, leaching of nutrients and other cations and anions from natural and managed
soil systems should be investigated. Further definition of sensitive areas of the eastern
portion of North America should be accomplished so that field research programs can
be focused geographically in those areas where the impact is suspected of being
greatest.
229
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References
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15. Fennelly, P. F 1976. The origin and influence of airborne particulates. American
Scientist 64: 46-46.
16. Liljestrand, H. M., and J. J. Morgan. 1978. Chemical composition of acid precipi-
tation in Pasadena, California. Env. Sci. and Tech. 12: 1271-1273.
17. McColl, J. G., and D. S. Bush. 1978. Precipitation and throughfall chemistry in
the San Francisco Bay area. J. Environ, dual. 7(3): 352-357.
18. Rennie, P J., and R. L. Halstead. 1977. The effects of sulfur on plants in
Canada. In: Sulfur and its Inorganic Derivatives in the Canadian Environment.
Environmental Secretariat, National Research Council of Canada. Publ. No.
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19. Whelpdale, D. M., and J. N. Galloway. 1979. An atmospheric sulfur budget for
eastern North America. Environment Canada, Atmospheric Environment Service,
Downsview, Ontario.
20. Braekke, F H. 1976. Impact of Acid Precipitation on Forest and Freshwater
Ecosystems in Norway. Summary Report on the Research Results from Phase
1 (1972-75) of the SNSF-Project. Research Report. FR6/76.NLVF/NTNF
Oslo-As, Norway.
21. Halstead, R. L., and P. J. Rennie. 1977. The effects of sulfur on soils in Canada.
In: Sulfur and its Inorganic Derivatives in the Canadian Environment. Environ-
mental Secretariat, National Research Council of Canada. Publ. No. 15015. pp.
426.
22. Rennie, P. J. 1978. Utilization of soils of the Boreal for forest production. In:
Proceedings Xlth International Congress of Soil Science, Symposium IV: Utiliza-
tion of Northern Soils, Edmonton, Alberta, pp. 305-331.
23. Wright, R. F. SNSF-Proj. TN 34/77 (NISK, As, 1977).
24. Schofield, C. L. 1976. Acid precipitation: effects on fish. Ambio. 5(5-6):
228-230.
25. Kramer, J. R. 1976. Geochemical and lithological factors in acid precipitation.
USDA Forest Service Gen. Tech. Rep. NE-23, pp. 611-618.
26. Glass, G. E., and O. L. Loucks, (eds.). 1979. Impacts of air pollutants on wilder-
ness areas of northern Minnesota. EPA Ecological Research Series (in press).
27. Johnson, N. M. 1979. Acid rain: neutralization within the Hubbard Brook
ecosystem and regional implications. Science 204: 497-499.
28. Katz, M. et al. 1939. Effects of sulfur dioxide on vegetation National Research
Council of Canada, Ottawa. Publ. No. 815. pp. 447.
29. Linzon, S. N. 1971. Economic effects of sulfur dioxide on forest growth. J. Air
Pollut. Control Assoc., 21: 81-86.
30. Sidhu, S. S. 1978. Patterns of fluoride accumulation in forest species as related
to symptoms and defoliation. Paper No. 78-24.7. In: Proceedings of the 71st
Annual Meeting of the Air Pollution Control Association, Houston, Texas.
(June).
31. Rennie, P J. 1978. Ecosystem responses to environmental pollutants. In: Pro-
ceedings of the Air Quality Criteria Workshop. Atmospheric Environment Service,
Downsview, Ontario, pp. 139-144.
32. Malhotra, S. S., and R. A. Blauel. 1979. Symptomology of Air Pollutant and
Natural Stresses on Boreal Forest Vegetation. A Field Diagnostic Tool to Detect
Air Pollutant Injury. Canadian Forestry Service, Edmonton, Alberta. Inf. Report.
NOR-X-185. pp. 84.
33. Robitaille, G. 1979. Pollution and the annual rings of Abies balsamea. In: Pro-
ceedings of the Contaminants in the Environment Conference, Quebec City.
(May).
34. Russell, E. J. 1950. Soil Conditions and Plant Growth. Eighth edition. Longmans,
Green & Co., London, New York, Toronto, p. 120.
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35. Wiklander, L. 1978. Leaching and acidification of soils. In: Electric Power
Research Institute (EPRI)/Central Electricity Research Laboratories (CERL)
Workshop on Effects of Acid Precipitation, Gatehouse-of-Fleet, Scotland.
(September).
36. Cowling, E. B., and L. S. Dochinger. 1979. Effects of acid rain on crops and
trees. ASCE Preprint #3598.
37. Wood, T., and F. H. Bormann. 1975. Increases in foliar leaching caused by
acification of an artificial mist. Ambio 4(4): 69-171.
38. Fairfax, J. Q. W., and N. W. Lepp. 1975. Effect of simulated "acid rain" on
cation loss from leaves. Nature. 255: 324-325.
39. Shriner, D. S. 1976. Effects of simulated rain acidified with sulfuric acid on
host-parasite interactions. Water and Soil Pollution. 8(1): 9-14.
40. Kratky, B. A., E. T. Fukunaga, J. W. Hylin, and R. T. Nakano. 1974. Volcanic
air pollution: deleterious effects on tomatoes. J. Environ. Qua/. 3(2): 138-140.
41. Tukey, H. B., Jr. 1970. The leaching of substances from plants. Annual Rev. of
Plant Physiology. 21: 305-324.
42. Hindawi, I. J., J. A. Rea, and W. L. Griffis. 1977. Response of bush bean
exposed to acid mist. Am. Jour. Botany, (in press).
43. Lee. J. J., and D. E. Weber. 1976. A study of the effects of acid rain on model
forest ecosystems. Proceedings of the 69th Annual Meeting of the Air Pollution
Control Association. Vol. 3, no. 76-25.5, pp. 1-17.
232
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AIR QUALITY STUDIES IN SUPPORT OF THE
OHIO RIVER BASIN ENERGY STUDY
Michael T. Mills, Ph.D.
Teknekron Research, Inc.
Lowell F. Smith, Ph.D.
Office of Environmental Engineering and Technology
U.S. Environmental Protection Agency
ORBES
The Ohio River Basin Energy Study (ORBES) is designed to assess the poten-
tial environmental, social, and economic impacts associated with the construction of
additional power plants in the Ohio River Basin. The original study area, as man-
dated by Congress, included parts of the four states of Illinois, Indiana, Kentucky,
Michael Mills
i
233
-------
UTILITY GROWTH
AND EMISSION
EMISSION AND SITING
CONSTRAINTS
and Ohio but has since been expanded to include parts of West Virginia and
Pennsylvania. The evaluation of air quality changes for different assumptions of power
demand, economic conditions, and regulatory constraints plays a central role in this
assessment. From the outset of the study, there has been the concern that the
locations of existing and future power plants along the major rivers (see Figures 1
through 3) could lead to elevated primary and secondary pollutant concentrations
during periods of persistent winds along these high density siting corridors (1).
The air quality analysis for ORBES is one part of the Integrated Technology
Assessment (ITA) process (Figure 4) which forecasts the growth and development
of the utility industry as a function of regulatory constraints, electricity demand,
economic conditions, and technologies and costs for electric generation and pollution
control. The actual projection of utility growth and emissions is carried out by use
of the EPA Utility Simulation Model (USM) which was described during the 1978
Interagency R&D meeting (2). The USM emission calculations are then input to an
air quality dispersion model along with appropriate meteorological data to obtain
estimates of air pollutant concentrations for comparison with applicable standards or
use in impact assessment. While this analysis is in principle straightforward, a number
of complications arise due to the intricacies of the regulatory process and lack of
validated models for certain pollutants and transport scales of interest. For a better
understanding of the air quality issues for the ORBES region, the following discussion
will deal separately with air quality constraints and impacts.
The Clean Air Act Amendments of 1977 impose certain air quality constraints
upon new source emission characteristics and siting. An emission constraint can be
viewed as an air quality constraint which deals with individual source characteristics
such as stack height, percentage of the pollutant removed, or quality of the fuel
burned. Examples of emission constraints are State Implementation Plans (SIP), New
Source Performance Standards (NSPS), Best Available Control Technology (BACT),
and Good Engineering Practice (GEP) stack heights. Siting constraints, on the other
hand, deal with the total emissions from an individual plant or group of plants, possi-
ble interactions with other plants in the area, and the potential impact on pollutant
nonattainment areas. Siting restrictions are embodied in Emission Offset Rules and
Standards for the Prevention of Significant Deterioration (PSD).
As it now stands, the USM considers several air quality constraints in the assign-
ment of future electric generating capacity on a county by county basis: current and
234
-------
FIGURE 2-Fossil steam units in the Ohio River Basin (1976-1982) in accordance with
NSPS
FIGURE 3-Fossil steam units in the Ohio River Basin (1983-2000) projected by the utility
simulation model in accordance with the revised new source performance standards
1 s
£ REGULATORY CONSTRAINTS
^
(~~^ AIR QUALITY
00 0
ENVIRONMENTAL
IMPACTS
ELECTRICITY PRICES
ft
\—| ELECTRIC UTILI
INVESTMENT M
OPERATING DECIS
r^
/> ^>
PRESENT AND „„,,.,,.,_..
Tnwrr 'CONTROL-
DEMANDS cosrs
1
TY
4D
IONS
^\
TECHNICAL
AND
ECONOMIC
CONDITIONS
) EMISSIONS
-/
FIGURE 4—The integrated technology assessment of electric utilities
235
-------
IMPORTANCE OF
STANDARDIZED MODELS
revised NSPS, SIP emission limitations for existing plants, and no post-1987 plant
siting in those counties designated as nonattainment for sulfur dioxide (S02) or total
suspended particulates (TSP) or in those counties containing designated PSD Class I
areas. An evaluation of other air quality constraints, however, requires the analysis of
local or subregional scale pollutant transport which is described through the application
of EPA standardized dispersion models. While the existence of these standardized
models does not preclude the use of more refined modeling techniques, they are
heavily relied upon by federal and state agencies for PSD review and therefore repre-
sent a de facto air quality constraint. For example, apart from the question of non-
attainment, the principal air quality constraint on the growth of coal-fired generating
capacity in the Ohio River Basin can be traced to the calculated second highest 3-hour
S02 concentration under the extremely unstable (A Stability) condition. This relatively
high concentration is expected to occur rather close to the plant in question and only
over a very limited area so that the chance of additive impacts is remote unless two
sources are extremely close to one another. This assumed maximum impact condition
allows the construction of additional plants in an area, each with emissions below a
certain limit, until the number of plants along the prevailing wind direction is suffi-
cient to exhaust the 24-hour or annual PSD increment for S02 in Class II areas (see
Table I). This example illustrates the importance of the standardized models in the
regulatory process. In recognition of this fact, we now briefly examine some of the
basic assumptions and operating characteristics of these models.
TABLE 1
Maximum allowable SO2 and TSP increments (pg/m ) under the Rules for Prevention of Significant
Deterioration
Class I
Class II
Class III
Particulate Matter
Annual geometric mean
24-hour maximum
5
10
19
37
37
75
Sulfur Dioxide
Annual arithmetic mean
24-hour maximum
3-hour maximum
2
5
25
20
91
512
40
182
700
GAUSSIAN PLUME
EQUATION
Calculation of short-term concentrations for comparison with standards is carried
out through the application of the steady state Gaussian plume equation on a sequen-
tial hourly basis. The vertical and horizontal standard deviation of plume concen-
trations depends on downwind distance, wind speed, solar elevation angle, cloud cover,
and the height of the lowest cloud layer. The parameterization of this dependency is
based primarily on experiments involving ground level tracer releases. The vertical
dispersion of pollutants is limited by the ground surface and the top of the mixing
layer so that for long downwind distances, the concentration becomes uniform within
this layer. Morning and afternoon mixing heights are estimated from the early morning
temperature sounding and the morning and afternoon surface temperature. Hourly
mixing heights are in turn estimated from morning and afternoon mixing heights by
use of a stability dependent interpolation scheme. The rise of the plume above the
stack top depends on the stack gas exit velocity, gas temperature, stack diameter,
ambient temperature, wind speed, and atmospheric stability. The wind speed used in
the plume rise and dilution calculation is adjusted to the top of the physical stack by
use of a stability-dependent power law. If the effective plume height is calculated to be
greater than the height of the mixed layer, then no concentration impact is assumed at
ground level for that hour. The effect of terrain is accounted for by reducing the
effective plume height by the difference between the receptor and stack base eleva-
236
-------
HOURLY AMBIENT
CONCENTRATIONS
MODEL REVISION
AIR QUALITY IMPACT
ANALYSIS
tions. Hourly concentrations are then calculated for a large number of receptor loca-
tions around the stack, using 5 years of hourly meteorological input data. These calcu-
lated concentrations are then screened to find the highest of all the second highest
3-hour and 24-hour concentrations for comparison with standards. If only 1 year of
meteorological data is available, then the highest of all the highest calculated con-
centrations at each receptor is selected.
From the preceding description of the PSD models, it can be seen that the
calculation of an hourly ambient concentration is a somewhat involved procedure. For
example, the wind speed not only enters into the calculation of plume dilution, it is
also used in the estimation of plume rise and the assignment of atmospheric stability
class. In spite of this built-in complexity, however, the critical impact condition for
various source types is calculated to occur under well defined meteorological
conditions.
The Stability A impact mentioned earlier is one example of a critical meteorolo-
gical condition for elevated point sources. The dispersion model will make this stability
class assignment for the midday hours of spring and summer months when the sky is
relatively clear and the winds are quite light. The highest or second highest 3-hour
concentration for this impact condition will occur when the wind flow vector falls
along the line joining the source and receptor for at least 1 hour or when the flow
vector is close to this line for 2 or 3 hours.
While the application of these standardized models acts as a constraint to the
siting of new power plants in the ORBES region, it should be noted that these models
will in time be revised, even to the extent of changing some of the basic model
assumptions. Every 5 years EPA will hold a conference to discuss suggested model
improvements. Modifications will be made based upon the results of field studies and
the comparison of model calculations with monitoring network data. In addition to
these basic changes to the models, guidance is continually provided by EPA regarding
detailed model application procedures and the suitability of emissions and meteorologi-
cal input data. These activities also introduce an element of time dependency into the
air quality constraints imposed by the use of these models in the licensing process.
The preceding discussion was designed to indicate the increasingly important role
of air quality modeling in the regulatory framework. With the standardization of these
models, they have become almost an extension of the regulations themselves. The air
quality impact analysis described in this paper, on the other hand, deals with those
pollutants and averaging times for which standards exist, but is not restricted to the
application of standardized models. In addition, the impact analysis for the ORBES
Region addresses those air quality issues for which standards are under consideration.
These include the formation and regional transport of sulfate and ozone, visibility
degradation and acid precipitation.
As was the case with the analysis of air quality constraints, this impact analysis
requires the use of dispersion models to relate emissions to ambient concentrations or
other air quality related values. Unfortunately many of these models are designed for
specific applications, have large computational and input data requirements, and are
not adequately validated. In some cases, the models are still under development or
have not been released. Due in part to these problems with the air quality models, the
initial portion of the ORBES air quality study was devoted to the collection of emis-
sions, meteorological and air quality data. The ORBES Aerometric Data Base includes
the following information:
• Continuous emissions, meteorological and air quality data from member utilities
of the East Central Area Reliability Council
• Surface and upper air data from the National Climatic Center
• Tower meteorological data from the Nuclear Regulatory Commission
• Historical, sulfate, 03, and TSP data from the National Aerometric Data Branch
237
-------
ANALYSIS OF SO2
• Emission inventories from the National Emissions Data System, Electric Power
Research Institute and Brookhaven National Laboratory
• Satellite photographs for identification of haze layers
• Precipitation chemistry data
The continuous monitoring data has been used to provide a realistic picture
of existing air quality throughout the region (see Figure 5). In particular, the network
data from the American Electric Power System provides excellent geographical and
historical coverage for S02, NOX, and TSP. In addition, 8 of the II networks have
meteorological towers and the remaining 3 have ground based wind instruments. For
all of the networks combined, there are a total of 65 SC>2, 14 NOX, and 64 TSP
monitors with at least 3 years of data at each site. Before the acquisition and analysis
of this data, the determination of regional SC>2 and TSP concentrations was difficult
since much of the data was taken in cities and towns and in many cases only repre-
sented measurements taken every 6 days. In addition, very little data was available to
estimate peak 3-hour S02 concentrations since most of the measurements consisted of
24-hour bubbler samples. The SO2 and meteorological data from these power plant
monitoring networks has also been extensively analyzed to study the influence of
meteorological parameters upon the observed hourly concentrations (3). The following
information has been obtained from this analysis:
• Cumulative frequency distributions of 1-hour, 3-hour, and 24-hour SO2 con-
centrations for each site-year of data. Also given are the mean, standard devia-
tion, and highest and second highest values along with their time and date of
occurrence for each of the averaging times.
• Average hourly SC>2 concentrations for each 16 wind directions and 5 wind
speed classes. In addition, the yearly frequency of occurrence of 1-hour S02
concentrations over 100 ;ugrrr3 js specified for each wind direction and wind
speed class.
• Relative frequency of occurrence by stability class of a particular wind speed
and wind direction range.
• Frequency of occurrence of cases of persistent wind by wind direction class,
wind speed class, and duration of persistence. For this analysis, persistence
was defined as a period of 7 hours or greater during which the wind direction
did not vary by more than 11 degrees and the wind speed by more than 2.5
msec"1
RESULTS OF SO2
ANALYSIS
• Summary of the emissions, meteorological, and air quality data for those days on
which the highest 25 daily SC>2 concentrations were reported. For each
network-year, 25 S02 24-hour episodes are selected.
The preceding analyses are currently being extended to TSP and NOX concentra-
tions. Some of the most significant results of the ORBES air quality work have come
from an analysis of SO2 episodes observed by these networks. From this analysis a
climatology of worst case meteorological conditions has been developed not only for
source specific impacts but also for periods of elevated background SC>2 concentra-
tions. In the lower Ohio Valley, the highest 24-hour SO2 concentrations are associated
with moderate to strong persistent winds from the south-southwest. On the other
hand, the highest 3-hour and 24-hour SO2 concentrations in the upper portion of the
Ohio Valley are often associated with a large, slow moving high pressure system. In
this case, the S02 emitted overnight is trapped and then brought to the ground at
midday in response to the heating of the ground surface. An example of this sharp
midday peak of SO2 is shown in Figure 6 for several monitors at the AEP Muskingum
Plant. If the 25 episode dates for each network are examined, there appear days or
groups of days on which more than one network reports an episode. This clustering of
episode dates can extend an entire month as was the case in October 1974 and
January 1977. The 24-hour SO2 concentrations during these periods were some of the
highest of the 25 selected for each network. This phenonmenon is due to the extent
238
-------
KEY
• Existing Power Plants
D Plants Under Construction
• Monitors
INDIANA
WEST VIRGINIA
FIGURE 5-Map of the AEP network locations showing second highest 3-hour SC>2
concentrations (ng/m3j for 1976
«
ation (jug
SC>2 C
-X
KEY:
Hackney
Beverly
„ Rich Valley
1 2 34 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
HOUR
FIGURE 6-^Diurnal variation of SC>2 concentrations at the Hackney, Beverly and Rich
Valley sites of the Muskingitm network on April 14, 1976
239
-------
VARIATION IN DISPERSION
METEOROLOGY
EVALUATION OF POINT
SOURCE MODELS
and movement of synoptic scale features and their associated worst case, meteorological
conditions across the region. In some cases, not only do the critical meteorological
conditions extend over more than one network, but actual regional scale transport of
S02 can occur. This appears to have been the case during January 1977 when plume
trapping and recirculation occurred with the frequent passage of cold high pressure
systems.
The variation in dispersion meteorology from one year to the next is illustrated
in Figure 7, which shows substantially fewer monitoring network S02 episodes during
January 1976 than January 1977. The first implication of this result is the difficulty in
the assignment of a base year concentration for 3-hour and 24-hour averaging times. A
more important implication is that any program designed to examine the validity of a
particular dispersion modeling technique must involve an analysis of several years of
monitoring data. Only in this case can one be assured that a reasonable fraction of the
worst-case meteorological conditions have been examined.
In light of this extended record of air quality and meteorological data at each
of the network sites, the EPA Office of Air Quality Planning and Standards and the
Meteorology and Assessment Division are making use of this data base for the evalua-
tion of the point source regulatory models which were described earlier. An important
aspect to this evaluation is the comparison of the meteorological conditions for the
10
9
8
7
6
5
4
3
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O 1
W '
0.
UJ
u- in
O10
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Z
7
6
5
3
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i
r
i
MAXIMUM NUMBER OF EPISODES
JANUARY 1976
—
i r~i
n n n n n
MAXIMUM NUMBER OF EPISODES
—
JANUARY 1977
r n n
0 24 6 8 10 12 14 16 18 20 22 24 26 28 30
DAY
FIGURE 7-Number of AEP network SO2 24-hour episodes during January of 1976
and 1977. The episode days are selected on the basis of the highest 25 daily SO2
concentrations observed for each network-year.
240
-------
EPISODE ANALYSIS
observed and calculated 25 highest 3-hour and 24-hour concentrations. For the periods
of the highest observed concentrations, a case by case comparison of observations and
model calculations will be carried out. While an actual quantitative comparison of
observed and calculated hourly concentrations is difficult because of the uncertainty of
the actual plume centerline location, it will be evident whether the model could have
possibly described the event. Of special interest will be the evaluation of the calculated
A-Stability impacts mentioned earlier in connection with the discussion of air quality
constraints and standardized point source models. Our analysis to date has identified a
number of daytime light wind 3-hour SO2 episodes similar to the one shown in Figure
6, but the concentration peak extends over a much wider area and to a greater
distance from the plant than would be calculated by use of the A-Stability vertical
dispersion curve. If the evaluation study identifies this observed light wind 3-hour
impact as critical for elevated point sources, this implies that additive short-term
impacts would be an important factor in the PSD analysis.
This treatment of air pollution episodes has been extended to other portions
of the ORBES Aerometric Data Base to obtain a better understanding of regional
pollutant transport and transformation characteristics during periods of observed
high concentrations. This episode analysis has been conducted principally with sulfate,
ozone, and TSP data from the National Aerometric Data Branch. Whenever possible,
these data have been supplemented with measurements from the Sulfate Regional
Experiment (4) and the Tennessee Valley Authority. For each pollutant and year,
the data were screened to find for each day the number of monitoring locations
reporting a concentration greater than a specified threshold value and the total number
of monitors reporting on that day. In spite of the every-6-day sampling schedule for
sulfate, this has proved to be a reliable way for the identification of episodes. Since
these episodes take several days to develop, the probability of missing an episode is
smaller than would be indicated by the once-every-6-day coverage. A selection of
ozone episodes is performed by means of a similar threshold analysis of 1 p.m. ozone
concentrations.
The most striking result from this analysis is the simultaneous occurrence of
sulfate and ozone episodes. One such case is shown in Figure 8, which is based on
FIGURE 8-Spatial distribution of sulfate and ozone for August 22, 1976
241
-------
SIMULTANEOUS OCCURRENCE
OF EPISODES
average sulfate and ozone concentrations for each Air Qualtiy Control Region (5). The
August 22, 1976, case is an interesting episode because it shows a recirculation of
pollutants within a relatively small region of eastern Ohio and western Pennsylvania.
This recirculation is indicated by the air parcel trajectories shown in Figure 9. During
August 21 and 22, there was no significant movement of the high pressure center just
south of Lake Erie. In fact, the entire eastern United States was dominated by high
pressure with a weak gradient. The ozone episode began on August 18 with 38 of the
monitoring stations exceeding the 0.08-ppm level. This number grew to reach a peak of
117 monitors exceeding this level on August 21 and then declined to 99 on the follow-
ing day. This was also a period of reduced visibility throughout the midwest and
northeast. The enhanced satellite photograph (see Figure 10) made available by Dr.
Walter Lyons shows the extent of the haze layer on this day. The haze shown in this
photograph is most likely due to the presence of fine particulates which, in large
measure, are produced by the conversion of tall stack sulfur dioxide emissions to
sulfate.
In addition to the recirculation condition, another typical summertime sulfate
episode has been found from an analysis of the data. This episode is characterized by
persistent southwesterly winds in advance of an approaching cold front. The pattern of
-• Trajectory Start at OOZ
Trajectory Start at I 2Z
Origin of Trajectory
FIGURE 9-Forward running air parcel trajectories (600-meter level) beginning August 20,
1976. Interval between trajectory points is 12 hours.
242
-------
-
FIGURE '\Q-Satellite photo for August 22, 1976, showing the haze layer over the midwest
and northeast
243
-------
LOCAL AND REGIONAL
ANALYSES
sulfate concentrations for August 27, 1974 (see Figure 11) is an example of one of
these persistent wind episodes. The highest sulfate concentrations during this period
were confined to the warm sector of an eastward moving occluded frontal system.
These analyses of local and regional air quality data have provided much more
useful information than would have been gained through the routine application of
existing models. In the first place, the data analysis gave a picture of existing air
quality throughout the ORBES region. Moreover, it has made possible the identifica-
tion of critical meteorological conditions for elevated pollutant concentrations. An
understanding of the meteorological conditions associated with air pollution episodes is
essential since many of the air quality standards and allowable increments are ex-
pressed in terms of concentrations which may be exceeded only once per year. Damage
to vegetation is a strong function of the peak SC>2 and ozone concentrations during
the summer months. Unfortunately, most of the existing air quality models have not
been designed to specifically deal with these episodes, but instead incorporate detailed
algorithms for the description of all possible conditions. Without first understanding
the worst-case meteorological conditions from an analysis of ambient data, a modeler
could devote years of effort to the development of a detailed model which could be of
little use for the calculation of concentrations under the actual critical conditions.
Another benefit from the analysis of air quality and meteorological data is the finding
that simpler modeling approaches can be used, so that computing and input data
Precipitation >0.01"
.L Low Pressure Center
iy \qp yjf cold Front
*""*"•»-• 24-Hour Average Sulfate
Concentration (pg/m3)
±1 High Pressure Center
Stationary Front
A A dfe
Occluded Front
FIGURE tl—Isopleths of sulfate concentrations and synoptic weather patterns for August
27, 1974
244
-------
MODELING APPROACH
DEVELOPED
requirements will not be prohibitive for the user. These simpler modeling approaches
may actually yield more accurate results than the more complex models. For example,
detailed calculations of primary pollutant concentrations for an urban area are often
no more accurate than those obtained from a very simple area source model. This
result can occur since, for most air pollution problems, there are generally only a
few factors of major importance and if these are described properly, the model calcula-
tions will be reasonable. The inclusion of further complexity in a model, unless war-
ranted by an analysis of available data, may introduce a large component of unwanted
noise into the model predictions.
Based on the analysis of these air pollution episodes, a modeling approach has
been developed for the evaluation of air quality impacts for various energy growth
scenarios. Short-range pollutant impacts are based on the results from standardized
Gaussian models, modified to reflect the influence of observed critical meteorological
conditions. Since pollutant transport plays a crucial role in the occurrence of the
worst regional sulfate episodes, a regional model has been selected which employs
a very efficient, yet accurate, algorithm for the calculation of pollutant advection and
diffusion (6). The model also allows for the time-dependent transformation of SO2
to sulfate and the removal of both chemical species by dry and wet deposition. The
computational efficiency of this model allows its evaluation for a large number of
episode cases and its application to develop regional source-receptor relationships.
Model calculations of regional sulfate concentrations for the August 27, 1974 episode
are shown in Figure 12. A large fraction of the sulfate observed in the Upper Ohio
Valley on this day can be traced to S02 emissions in the lower part of the valley (7).
During a light wind stagnation condition similar to the August 22, 1976 episode,
however, emissions in the Upper Ohio Valley can actually be transported as sulfates
down the valley. Regional model calculations are currently being carried out for
additional episode cases to estimate the change in regional SO2 and sulfate concentra-
tions for several ORBES energy growth scenarios under different governmental regula-
tory policies and future power-plant siting patterns in the Ohio River Basin.
FIGURE 12—Sulfate levels (ng/m3j predicted by the regional sulfate model for August 27,
1974
245
-------
References
1. Gage, S.J., Smith, L. F., Cukor, P. M., and Niemann, B. L. 1977. Long-Range
Transport of SOX/MS04 from the U.S. EPA/Teknekron Integrated Technology
Assessment of Electric Utility Energy Systems. Paper presented at the Inter-
national Symposium on Sulfur in the Atmosphere, Dubrovnik, Yugoslavia, 7-14
September.
2. Cukor, P. M., Large, D. B., Niemann, B. L., Smith, L. F., and Van Horn, A. J.
1978. An Integrated Technology Assessment of Electric Utility Energy Systems.
Paper presented at the Third National Interagency Energy/Environment R&D
Program Conference, sponsored by the U.S. Environmental Protection Agency,
Office of Energy, Minerals and Industry, Washington, D.C. (June).
3. Mills, M. T. 1979. Data Base for the Evaluation of Short-Range Dispersion
Models. R-001-EPA-79. Prepared for the U.S. Environmental Protection Agency,
Office of Energy, Minerals and Industry. Berkeley, Calif.: Teknekron, Inc.
(January).
4. Hidy, G. M., Mueller, P. K., and Tong, E. Y 1978. Spatial and Temporal
Distributions of Airborne Sulfate in parts of the United States. Atmospheric
Environment, 12:735-52.
5. Tong, E. Y., Mills, M. T., Niemann, B. L., and Smith, L. F 1979.
Characterization of Regional Sulfate/Oxidant Episodes in the Eastern United
States and Canada. Paper presented at the APCA Annual Meeting (June).
6. Mills, M. T., and Hirata, A. A. 1978. A Multi-Scale Transport and Dispersion
Model for Local and Regional Scale Sulfur Dioxide/Sulfate Concentrations:
Formulation and Initial Evaluation. Paper presented at the Ninth International
Technical Meeting on Air Pollution Modeling and Its Application, NATO/CCMS
Air Pollution Pilot Study Assessment, Methodology and Modeling, Toronto,
Canada, 28-31 August.
7. Niemann, B. L., and Mahan, A. L. 1978. Interim Report, Impact of Long-Range
Transport of Pollutants on Air Quality in the Commonwealth of Pennsylvania.
Prepared for the U.S. Environmental Protection Agency, Office of Energy,
Minerals and Industry. Berkeley, Calif.: Teknekron, Inc. (May).
246
-------
WH^<
&
answers
Dr. Theodore C. Doege
American Medical Association
Benjamin Linsky, P.E.
West Virginia University
QUESTION
For years physicians have looked at effects of
influenza in terms of excess mortality. Are there any
current plans to look at the spectacular air pollution
effects which we have just seen documented in terms
of excess mortai/ity in the areas covered by those systems
of pollutants?
RESPONSE: Dr. William Wilson (EPA)
There are no fully developed plans, but there
are discussions among health effects people about the
possibility of bringing in mobile health effects units to
look for more subtle effects of pollution in relationship
to these episodes. I do not think anyone has suggested
looking for excess mortality, but that would be simpler
than taking the vans in and looking for changes in respira-
tory function.
COMMENT
There is a study done by the West Virginia Depart-
ment of Natural Resources which found streams that had
been fishable and stockable have become unfishable and
unstockable because of acid rain. I hope the author will
put the report into the peer review literature.
QUESTION
The visibility limitation at Lake Tahoe is set at 20
miles, specifically so people can see across the lake. Is this
sort of criterion valid when used by state and local
governments in setting minimum visibility limitations?
RESPONSE: Dr. Wilson
Different standards are needed for different parts of
the country, depending on what objects you want to see
and how badly you want to see them. The people of New
Mexico maintain that if you cannot see the mountains in
New Mexico, why live there? Visibility certainly is a
247
-------
consideration in terms of property values. Another
important thing to consider is that if you want to see
something 20 miles away you may have to set your
standard in terms of a visibility distance of more like 100
miles, a fact probably not realized at the time of the
Lake Tahoe studies. There is a difference between visibil-
ity distance and visual air quality. Local agencies will have
to consider this in setting standards for their emission
sources. They will have to consider as well that their
emission sources not only impact them locally but affect
other areas.
248
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session 6
-------
ASSESSMENT OF THE CARCINOGENIC RISK
FROM ENERGY-RELATED ORGANICS
J Michael Holland
J. Michael Holland
William M. Eisenhower
Larry C. Gipson
Lawton H. Smith
Thomas J. Stephens
Mary S. Whitaker
Biology Division
Oak Ridge National Laboratory
UNKNOWN-REFERENCE
DOSAGE COMPARISON
The extraction, refining, and use of natural petroleum over the last half century
have resulted in extensive industry experience with these materials. Based upon this
experience, there is justifiable confidence in the adequacy of current procedures to
limit occupational dermatoses and skin cancer arising from contact with natural petro-
leum and distillate fractions. This, in part, may result from the fact that natural
petroleums possess a low order of intrinsic carcinogenicty (1). By contrast, it is well
documented that coal liquids and shale oils are human skin carcinogens, under condi-
tions of prolonged or unregulated exposure (2-4). Given the inevitable need for massive
quantities of these materials it is essential that their potential for skin contact toxicity
and carcinogenicity be assessed. There is an additional question concerning whether the
greater skin carcinogenic potency manifest by syncrudes will be reflected in finished
products that may eventually enter commerce.
To facilitate risk-benefit decisions our approach has been to obtain comparative
and quantitative data concerning the skin carcinogenicity of syncrudes, derived from
various starting materials and by different processes relative to both natural petroleum
and the pure reference carcinogen, benzo(a)pyrene (BP). To quantitate the response,
we have adapted biostatistical methods that have been used for the comparative bio-
assay of tobacco smoke condensates (5). Using these approaches, it eventually will
be possible to relate the dose response obtained for a specific syncrude to that ob-
tained for BP. By comparing the dosages, between unknown and the reference, re-
251
-------
TEST MATERIALS
quired to elicit a common risk or probability for skin cancer, we can accurately and
reproducibly compare different materials, as well as assess the importance of various
bioassay conditions (6).
Materials examined by us have been obtained from a variety of small scale
process simulations or process development units. For this reason the findings may or
may not be relevant to larger scale or commercial processes that utilize similar source
material. The question concerning whether these data reflect a trend or reveal charac-
teristics applicable to broad classes of generically related crude liquids is still the
subject of ongoing experimentation. Our primary use of these materials, to date, has
been to establish appropriate bioassay conditions for reliable, and potentially extrapo-
latable, analysis of the skin carcinogenicity of generically similar materials. It is antici-
pated that this knowledge and experience will facilitate analysis of materials that may
some day be produced commercially. Table 1 summarizes information concerning the
general characteristics of the test materials. Additional detail concerning their chemical
and physical characteristics has been published elsewhere (7,8).
Materials have been tested for carcinogenic activity by diluting them in a hetero-
geneous solvent. The solvent consisted, by volume, of 30% acetone and 70% cyclo-
hexane. This mixture was selected because it would permit solution or uniform dis-
persal of all the test materials. Test solutions were made fresh weekly and applied,
using a 50 microliter automatic pipette. Equal numbers of male and female C3Hf/He
inbred mice, 10 weeks old at the start of each experiment, were used. Details con-
cerning experimental animals and procedures can be found elsewhere (6,9).
Data are presented for two separate experiments. The first study involved 3 times
weekly (Monday, Wednesday, Friday) application of a 50% (w/v) concentration of the
various syncrudes as well as the composite natural petroleum to groups of 30 mice for
20 weeks. Following this exposure, the mice were held for an additional 20 weeks to
allow expression of skin lesions, in the absence of continued application of the test
materials. The total period of observation of these animals was approximately 300
days. In the second experiment, groups of 20 mice were exposed to serial dilutions of
TABLE 1
Characteristics of materials tested for skin carcinogenicity
SKIN CARCINOGENICITY
Material
Wilmington, California*
South Swan Hills, Alberta, Canada*
Prudhoe Bay, Alaska*
Gach Seran, Iran*
Louisiana-Mississippi Sweet
Arabian Light
Shale Oil'f
Coed Syncrude
Synthoil Syncrude
Type
Natural
Natural
Natural
Natural
Natural
Natural
Centrifuged
crude product
Hydrotreated
product oil
Centrifuged
crude product
Specific
Gravity
0.938
0.826
0.893
0.880
0.825
0.858
0.909
0.940
1.136
Wt. %
Sulfur
1.59
0.11
0.82
1.57
0.17
1.80
0.93
0.05
0.52
Viscosity
(Sec.100°F)
470
37
84
72
50
46
66
48
80(180°F)
Pour
Point
<°F)
<5
<5
15
<5
<5
<30
30
43
_
Color
Brownish
Black
Brownish
Green
Brownish
Black
Brownish
Black
Brownish
Green
Brownish
Black
Brownish
Black
Pale
Yellow
Brownish
Black
Wt. %
Nitrogen
0.631
0.056
0.230
0.226
0.067
0.1-0.2
1.14
0.05
1.30
* Bureau mines routine crude oil analysis. Data provided by J. Dooley, Bartlesville' Energy Technology Center, Bartlesville, Oklahoma.
t Analysis not based on these specific samples and therefore the data are approximate and given for comparison purposes only: provided by
J. Dooley.
$ Laramie Energy Technology Center, Run No. 14, Colorado Shale, Rifle, Colorado. Fisher assay 24.4 gallons/ton from a 150 ton above
ground simulated in situ retort. Data provided by John McKay.
252
-------
the same materials, starting at 50%. Exposure was twice weekly (Monday and
Thursday) for 30 weeks followed by a 20-week expression period. The total observa-
tion period of these animals was approximately 350 days. Taken together, the two
experiments allow a comparison of the materials as a function of temporal aspects
of exposure. In both experiments, animals received 60 exposures. However, in the first
study the 60 doses were applied in 20 weeks, but in the second, 30 weeks were
required.
TEST RESULTS The results, expressed in terms of grossly typical squamous carcinoma, are listed
in Table 2 for the 3/wk-20 week exposure and in Table 3 for the 2/wk-30 week
exposure. Under both treatment conditions, the syncrudes were found to be efficient
skin carcinogens while natural petroleums failed to induce skin cancer. In the 20-week
study, both synthoil and shale oil were more active than COED, with synthoil ex-
hibiting a slightly greater activity than with shale oil. This pattern was duplicated in
the 30 week study with the order of carcinogenic activity, synthoil>shale
oil>COED»natural petroleum. Natural petroleum, while negative under these experi-
mental conditions, does possess a low order of carcinogenicity. In other experiments in
TABLE 2
Epidermal carcinogenicity of fossil liquids following 3 times weekly skin application for 20 weeks at a
50% concentration
Percent of Mice With Average Latency Percent
Material Squamous Carcinoma (Days±SE) Mortality
Synthoil
Coed
Shale Oil
Petroleum Blend
63
37
47
0
153±
192 ±
151 +
-
8
13
14
20
3
37
0
TABLE 3
Epidermal carcinogenicity of fossil liquids following 2 times weekly skin application for 30 weeks at
various concentrations
Material
Synthoil
Coed
Shale Oil
Wilmington
Petroleum
Percent (W/V)
Concentration
50
25
12
6
50
25
12
6
50
25
12
6
50
25
12
6
Percent of Mice With
Squamous Carcinoma
80
35
10
0
10
5
0
0
35
5
0
0
0
0
0
0
Average
Latency
214±11
238±22
287±50
-
329+17
253
—
-
208±9
213
—
-
—
_
—
Percent
Mortality
45
5
5
0
0
0
0
0
30
0
0
0
0
0
0
0
253
-------
INCREASED INTERVAL
DECREASED RATE
which a 0.2% concentration of the composite petroleum was applied 3 times weekly
for 24 months, an 8% final incidence of squamous carcinoma was obtained with an
average latency of 658±22 days (10).
The temporal distribution of tumor latencies is illustrated in Figure 1 for the 20
and 30 week data, respectively. These curves reveal that, in general, increasing the
inter-treatment interval from 56 (3/wk) to 84 (2/wk) hours is accompanied by a longer
average latency and decreased skin cancer frequency particularly with COED, but also
evident for shale oil. Interestingly, while skin tumors developed at later times, the
cumulative incidence was actually greater when mice were exposed to synthoil at a
reduced dose rate. This suggests that synthoil is less subject to a decreased carcinogenic
effect as a result of an increased interval between successive exposures.
60-
40-
~ 20H
0
CD
LLJ
Q
o
^ 80-
60-
40-
20-
0
B
i
o
6
6 •
o'
6' !
0 50 100 150 200 250 300 350
LATENCY (DAYS)
FIGURE 1—,A_ Incidence of squamous carcinoma included by three times weekly application
of 50% solutions of synthoil (O), shale oil (•) or coed (A) syncrudes for 20 weeks, B
Incidence of squamous carcinoma induced by two times weekly application of 50% solutions
of synthoil, shale oil, or COED (same symbols), for 30 weeks.
254
-------
DIFFERENCES
AMONG MATERIALS
The difference among the various materials are more clearly illustrated in Table
4, which contrasts the average time to occurrence of skin cancer as well as final inci-
dence in the two experiments.
RELATIVE POTENCY
TABLE 4
The effect of dose rate on cumulative incidence and average latency of skin cancer induction by
syncrudes
Intertreatment % Average Dose Rate Effect
Material Interval (Mrs) Incidence Latency (±SE) Upon Tumor Expression
Synthoil
Coed
Shale Oil
56
84
56
84
56
84
63
80
37
10
47
35
153± 8
214±11
192+13
329±17
151+14
208+ 9
Enhanced Expression
Reduced Expression
Reduced Expression
Relative potency is a reproducible, quantitative, and extrapolatable means to
compare the skin carcinogenicity of any two materials, if each is applied under identi-
cal conditions to genetically homologous test animals. The approach we have taken
previously to establish the carcinogenic potency of a material has been to compare the
dose responses obtained for the test material with that obtained for reference skin
carcinogen, BP (6). Proportions of mice surviving over the duration of the study,
without skin tumor, are fitted to a three parameter Weibull distribution by the maxi-
mum likelihood method. Dose responses, in terms of the model, for the unknown
compound or mixture and the reference carcinogen, are then compared by relating
doses of the unknown, relative to BP, that would be required to elicit a common
probability of skin cancer. This allows a quantitative estimate of the degree of differ-
ence between the two materials. This approach will enable us to reproducibly compare
different materials tested under standard conditions at different times. In addition it
will facilitate interspecies comparison because the reference carcinogen used is a com-
ponent of man's environment. As such, estimates of human population exposure to BP
will inevitably improve and with each improvement will come better appreciation of
the extent, if any, of adverse health impact attributable to observed differences in BP
exposure. With this common link between the two species, known BP dose responses,
then extrapolation of this to other hydrocarbon skin carcinogens will be facilitated.
For purposes of the present communication, data concerning the response of
C3H mice to topical application of BP in the same acetone-cyclohexane solvent, has
been summarized in Table 5. BP was applied at concentrations ranging from 0.1% to
0.004% which are much lower than were used for any of the fossil liquids, but on the
TABLE 5
Skin cancer induction by Benzo(A)pyrene applied three times weekly*
Percent Concentration
(Wt/Vol)
0.1
0.02
0.004
Percent of Mice with
Squamous Carcinoma*
100
100
90
Average
Latencyt
139(4)
206(7)
533(5)
* Duration of exposure at lowest dose was 24 months.
t Days ± standard error.
255
-------
FLUORESCENCE
MICROPHOTOMETRY
same 3-times-weekly schedule. The concentration of BP that came closest to yielding
an average tumor latency equal to that of synthoil was somewhat less than 0.1%. Thus
a 0.1% solution of BP is approximately equipotent to a 50% solution of synthoil, all
other conditions being equal. A crude estimate of relative potency can be obtained
from this relationship by expressing potency as a ratio of these two percentage
concentrations which in this case is 500. Therefore, as a first approximation, it would
appear that synthoil is 500 times less active a skin carcinogen than BP. This estimate is
preliminary and subject to refinement as the full dose response relationship, for both
the test material and the reference carcinogen, is taken into account.
To better understand the basis for the difference in carcinogenicity observed
among the syncrudes, we have developed analytical methods to observe and quantitate
the movement and localization of syncrudes in the skin (9). At various times after
standardized skin application, frozen sections are obtained and the distribution of
syncrude is determined by fluorescence microphotometry. All fossil liquids thus far
examined are highly fluorescent and thus this measure provides a convenient marker
for observing skin distribution. It also should be kept in mind that polyaromatic
hydrocarbons, known to be a carcinogenic component of fossil liquids, are also highly
fluorescent and that this feature was exploited in their isolation and identification
(11).
Using this approach we have compared the intensity and distribution of skin
fluorescence for each of the syncrudes as well as the composite petroleum. The data
in Table 6 indicate the observed fluorescence intensity (in arbitrary units) at specific
locations. Solution of each material was adjusted to contain 2 mg solids per ml. One
hundred microliters of this solution was applied, using a micropipette being careful to
ensure as uniform a dispersal as possible. Using dye solutions, it was independently
established that this volume of an acetone-cyclohexane solvent will reproducibly cover
an area approximately 100 cm2. From this relationship, we estimate the area concen-
tration to have been 200 jug/cm2.
TABLE 6
Distribution of fluorescence following topical application of petroleum liquids
Site of
Measurement
Skin Surface
Sebaceous
Gland
Papillary
Dermis
Time After
Application
1 hr
4hr
24 hr
8 days
14 days
1 hr
4hr
24 hr
8 days
14 days
1 hr
4hr
24 hr
8 days
14 days
Average Fluorescence Intensity
Synthoil
185(32)
219 (58)
107 (26)
70 (25)
37(7)
540(123)
422(101)
454(114)
112 (21)
42(11)
28(2)
28(2)
27(2)
27(1)
25(1)
Coed
75(11)
87(11)
98(13)
40(10)
28(6)
172(49)
185(61)
190 (24)
43(6)
23(1)
29(2)
29(2)
29(3)
27(2)
25(1)
#
Shale Oil Composite Crude
49(14)
37(5)
42(8)
31 (2)
25(2)
70(21)
66(12)
109(21)
29(1)
25(1)
20(1)
24(1)
24(1)
24(1)
25(1)
65(11)
70(15)
52 (22)
28(2)
25(1)
137(44)
140(88)
135(40)
27(1)
25(1)
26(2)
24(1)
26(1)
25(1)
25(1)
*Arbitrary fluorescence units ± standard error. Tissue background in mice treated with
solvent only was approximately 25 units.
256
-------
FLUORESCENCE INTENSITY
MOUSE SKIN
CARCINOGENESIS DATA
Fluorescence intensity was determined at specific sites within frozen sectioned
skin, at fixed times. Concentration of fluorescent material was observed to occur in
sebaceous glands. Fluorescence intensity was greatest with synthoil and least for COED
at all times. The degree of initial fluorescence was also positively correlated with the
speed of clearance. It is interesting to note that fluorescence significantly above
dermal background was detectable in the sebaceous glands of mice, for up to 14 days
following a single skin application of synthoil. Thus synthoil exhibited a high affinity
for skin lipid while the other materials were cleared rapidly. It may be significant that
the effect of increasing the interval between successive exposures was less pronounced
for synthoil than with the other compounds. One possible explanation for this may
well have been that synthoil persists in skin longer than the other materials and thus
there is a less pronounced effect introduced by increasing the interval between succes-
sive exposures.
The value and relevance of animal carcinogenesis bioassay data could be increased
significantly if a means could be found to directly compare the responsiveness of
human skin and experimental animal skin to the same test materials under identical in
vivo conditions. We feel that it may be feasible to do this using the genetically
athymic nude mouse (12). This animal is incapable of recognizing and thus rejecting
foreign tissue grafts. We have established a pathogen-free colony of these mice under
conditions which maximize experimental flexibility. We have further determined that
it is feasible to establish xenografts of human skin for periods sufficiently long (up
to 300 days) to easily compare more potent skin carcinogens. The essential micro-
scopic differences between mouse skin and human skin as well as an illustration of the
graft procedure are given in Figure 2. Panel _A_is a microscopic section of mouse skin
* '^«p
"'
FIGURE 2-^A Light microscope section of mouse skin revealing a thin cellular epidermis. B
Similar section of human skin revealing a thicker, more cellular epidermis. C_ Human skin
grafted to the back of an athymic nude mouse. Healing is complete with no overt evidence of
inflammation. D Microscopic section of human skin graft. The margin of the graft (arrow)
reveals an abrupt transition from epidermis characteristically human to that characteristic of
the nude mouse.
257
-------
SUMMARY AND CONCLUSIONS
MORE MODELS NEEDED
revealing a characteristic of this species, an exceedingly thin epidermis. Panel J3 is a
similar section of human skin depicting a more highly cellular and physically less
permeable epidermis. Panel CJs a gross photograph of an athymic nude mouse bearing
a well established graft of human skin. The human skin graft is easily distinguished
because the host mouse is albino and human skin is pigmented. Evidence that these
grafts are well tolerated by athymic mice, without evidence of rejection, is revealed in
panel JX This is a microscopic section of a skin graft like that displayed in panel C,
which reveals that the thicker epidermis characteristic of human skin is preserved and
that mouse and human epidermis merge without a noticeable interruption.
These findings, while still preliminary, are encouraging because they point a way
to achieve the goal mentioned previously. If a sufficient number of these grafts can be
established to allow direct application of reference carcinogen solutions, then it should
be possible to compare the biological response of human skin to chemical and physical
agents, singly and in combination, and to compare directly differences in tissue and
cellular and molecular aspects of the response across species lines. To control the
possible interference introduced by the graft procedure itself due to alteration of nerve
supply and microvasculature, control grafts of animal skin of known carcinogen suscep-
tibility can be tested in parallel with the human skin. Any difference in latency,
histogenesis, or biological behavior of tumors induced in the graft versus those induced
in the same tissue on its natural host could then be assumed to be constant regardless
of species and thus factored into the interpretation of the data.
We have determined that three synthetically-derived fossil liquids are more potent
skin carcinogens than natural petroleum. None of the syncrudes approached the
specific carcinogenicity of a reference carcinogenic hydrocarbon, benzo(a)pyrene (BP).
By comparison of the dose rates necessary to achieve similar average tumor latencies,
under identical experimental conditions, it was estimated that synthoil had a mouse
skin carcinogenicity one five hundredth that of pure BP.
Increasing the interval between successive exposures, while keeping the total
number of exposures constant, had the effect of decreasing risk of skin cancer for both
shale oil and COED but not for synthoil. The percent of mice developing skin cancer
with the latter material actually increased as the dose rate was reduced from three to
two exposures per week. We interpret this as an indication that high dose rate applica-
tion of synthoil may actually inhibit either skin cancer induction or expression, proba-
bly as a result of toxic components present in the whole material. As the dose rate is
decreased, there is sufficient time between successive exposures for the skin to elimi-
nate or recover from the toxic but not the carcinogenic effect and thus expression of
neoplastically transformed epithelial cells is enhanced. Another factor that also may
contribute to a diminished dose rate effect is the slower skin clearance of synthoil
relative to any of the other materials tested. Based upon fluorescence intensity as a
measure of the quantity of material trapped in sebaceous glands, synthoil components
were detected in sebaceous glands for up to 2 weeks following a single surface applica-
tion of synthoil while all other materials were observed to clear within 1 week. There-
fore the question of whether workers who are exposed only infrequently or accident-
ally are at as great a risk as those who are exposed continuously could depend upon
how rapidly the material is cleared from the skin. For syncrudes similar to the present
shale oil and COED, detoxification and skin clearance would be expected to be rapid
and therefore increasing the interval between exposures would be anticipated to result
in a decreased tumor risk. For materials with the skin clearance characteristics of
synthoil even infrequent exposure could pose a significant risk.
Future biological research in support of the synthetic fuels industry needs to
emphasize the potential applicability of animal carcinogenesis data to the question
of human risk. More comprehensive and relevant experimental models need to be
developed and evaluated for the purpose of risk quantitation. There is an additional
need to better understand the biological interactions between the target tissue and the
whole chemical mixture. We have explored the feasibility of using the athymic nude
mouse as an incubator host in order to compare the relative sensitivities of mammalian
skin to hydrocarbon carcinogens. This would provide direct information concerning
whether major species differences exist as well as provide a measure of the magnitude
of these differences under identical environmental and experimental conditions.
258
-------
References
1. "The Carcinogenic Action of Mineral Oils: A Chemical and Biological Study."
Medical Research Council, Special Report Series No. 306. Committee on the
Carcinogenic Action of Mineral Oils, London: Her Majesty's Stationery Office,
1968.
2. Scott, A. "The occupation dermatoses of the paraffin workers of the Scottish
shale oil industry, with a description of the system adopted and the results
obtained at the periodic examinations of these workers." Eighth Scientific
Report of the Imperial Cancer Fund. Taylor and Frances, London, 1923. pp.
85-142.
3. Henry, S. A. "Occupational cutaneous cancer attributable to certain chemicals in
industry." Brit. Med. Bull. 4: 389-401, 1947.
4. Smith, W. E., D. A. Sunderland, and K. Sugiura. "Experimental analysis of the
carcinogenic activity of certain petroleum products." Arch. Industr. Hyg. 4:
299-314, 1951.
5. Davis, R. F., P. N. Lee, and K. Rothwell. "A study of the dose response of
mouse skin to cigarette smoke condensate." Brit. J. Cancer 30: 146-156, 1974.
6. Holland, J. M., D. G. Gosslee, and N. J. Williams. "Epidermal carcinogenicity of
bis (2, 2-bis(p-glycidyloxyphenyl)-propane), and m-phenylenediamine in male and
female C3H and C57BL/6 mice." Cancer Research 39: 1718-1725, 1979.
7. Guerin, M. R., J. L. Epler, W. H. Griest, B. R. Clark, and T. K. Rao. "Polycyclic
aromatic hydrocarbons from fossil fuel conversion processes." Carcinogenesis:
Polynuclear Aromatic Hydrocarbons. Vol. 3 (P.W. Jones and R. I. Freudenthal,
Eds.), Raven Press, New York, 1978.
8. Griest, W. H., M. R. Guerin, B. R. Clark, C. Ho, I. B. Rubin, and A. R. Jones.
"Relative chemical composition of selected synthetic crudes." Proceedings of the
Symposium on Assessing the Industrial Hygiene Monitoring Needs for the Coal
Conversion and Oil Shale Industries. Brookhaven National Laboratory, Upton,
New York, November 6-7, 1978.
9. Holland, J. M., M. S. Whitaker, and J. W. Wesley. "Correlation of fluorescence
intensity and carcinogenic potency of synthetic and natural petroleums in mouse
skin." Am. Indust. Hygiene Assoc. J. 40: 496-503, 1979.
10. Holland, J. M., R. O. Rahn, L. H. Smith, B. R. Clark, S. S. Chang, and T. J.
Stephens. "Skin carcinogenicity of synthetic and natural petroleums." J. Occ.
Med., in press, 1979.
11. Cook. J. W., C. L. Hewett, and I. Hieger. "The isolation of a cancer-producing
hydrocarbon from coal tar." Parts I, II, and III, J. Chem. Soc. 395-405, 1933.
12. Pantelouris, E. M. "Absence of the thymus in a mouse mutant." Nature 217:
370-371, 1968.
259
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HEALTH CONSEQUENCES OF NITROGEN DIOXIDE EXPOSURE
Donald E. Gardner, Ph.D.
Judith A. Graham, Ph.D.
Health Effects Research Laboratory
U.S. Environmental Protection Agency
Daniel Menzel, Ph.D.
Departments of Pharmacology and Medicine
Duke University
Judith A Graham. Ph D
RESTRICTED EVALUATION
Biological effect of oxides of nitrogen have been evaluated in animals and man.
Of the oxides of nitrogen which have been studied and which occur in the atmosphere
through combustion of fossil fuels and subsequent conversion processes, nitrogen dioxide
(NO2> is the most toxic. Our knowledge of the toxicity of NO2 is still incomplete.
Yet, significant knowledge has been gained about its overall toxicity from the study of
(1) exposed animals, (2) individuals, and (3) communities.
Evaluation of the health effects of N02, demonstrated in all three of the above
major experimental approaches, permits improved understanding when taken as a whole.
In clinical human studies, safety of the volunteer is of paramount importance.
Therefore, chronic exposures cannot be performed and only limited endpoints such as
pulmonary function, clinical chemistry, and the like which are relatively benign can be
used. This leads to a restricted evaluation of N02 effects. However, the research is
highly controlled and the concentration and time of exposure to N02 can be directly
related to the observed effects in man.
BIOLOGICAL
PARAMETERS LIMITED
Information from population exposure studies is of value since humans are
investigated under natural conditions. However, this natural condition is so complex,
particularly with respect to individual exposure differences within the population, that
it is extremely difficult to relate a particular pattern of NO2 exposure to health effects.
Again, for ethical reasons, biological parameters are limited.
The strength of animal toxicological studies lies in the unlimited exposure
conditions and biological endpoints that can be used. Since animals and man have
261
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ANIMAL TOXICOLOGICAL
STUDIES
extensive physiological similarities, if a particular effect occurs in a number of animal
species, it is likely that this same effect occurs in humans. However, at this time, it is
not possible to extrapolate directly from animal studies to those concentrations of
NC>2 which will cause toxicity in man. With this as background, the review of the
health effects of NC>2 can be placed into better perspective. Several other excellent
reviews are available (1-3) and an Ambient Air Quality Criteria Document for Nitrogen
Oxides is presently being prepared by the Environmental Protection Agency.
Superficially, there appears to be a great similarity between the toxicity of N02
and ozone. A detailed analysis of the toxicity of NC>2, however, reveals that there are
as many dissimilarities as similarities. A summary of the research findings is in Table 1.
An unusual aspect of the toxicity of NC>2 is a delay between exposure and effect.
This temporal sequence is inherent in understanding the toxicity of NC>2 and has
important implications for the effects of both short-term and long-term exposures to
this air pollutant. Despite the differences in NO2 sensitivity between animal species
and the many different endpoints of toxicity, the sequence of events seems to be the
same. The sequence of events is illustrated in Figure 1. A composite has been drawn
from these different studies to illustrate the relationship with time following a single
short-term exposure of 4 hours or less. These results are drawn primarily from a single
species, the rat. A similar type of sequence could be drawn for other species. It is
likely that this sequence is the same for all mammalian species exposed under similar
conditions. These reactions will be obtained predominately with low concentrations of
NO2- As the concentration of NO2 is increased more than 100-fold over ambient
concentrations, complications arise which tend to obscure the sequence of events. It is
not clear, further, whether or not these higher concentrations are truly relevant to the
toxicity of NC>2 to man as it occurs in the atmosphere of urban areas. In any event,
the animal studies most important to determining the standards used in regulating
emissions are those more closely aligned to ambient concentrations of N02-
CELLULAR REACTION
Studies of the reaction of N02 with cellular constituents clearly illustrate that
the chemical reactions are essentially instantaneous (4,5) when compared with the
length of time required for demonstration of a biological effect. Most investigators
believe that the chemical reactions of N02 are dominantly with lipid components of
the cell (5). The reaction of NC>2 with the unsaturated lipids of cellular membranes
C/5
O
til
U.
u. 2
UJ
Q
ID
>
GC
UJ 1
V)
CO
O
I ""I 'I I
— EXPOSURE
CHEMICAL REACTION
SUSCEPTIBILITY TO
MICROORGANISMS
CELL DEATH (max. at 24 hr.)
BIOCHEMICAL INDICATORS
OF INJURY (max. at 18 hr.) ~
-— REPLACEMENT OF DEAD
AND INJURED CELLS
AND BIOCHEMICAL
INDICATORS OF REPAIR
(max. at 48 hr.)
I I . . I
(log scale) 4
10
hours
24 48
I
14
30
2 3
6 12
days
months
FIGURE 1-^Temporal sequence of injury and repair hypothesized from short-term single
exposures of less than 8 hours
262
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TABLE 1
Effects of nitrogen dioxide in animals
Concentration of NO_
Time of
Exposure
Species
Summary of Effects
References
ppm
0.1 + 2hr 188 +
daily spike 2 hr
of 1 daily
spike of
1,880
Continuous
6 mo
Mice
Emphysematous altera-
tions
82
0.25
470
4 hr/day
5 days/wk
24 or 36
days
Rabbits Swollen collagen fibers
in lung
32
0.3 -0.5
560 - 940
Continuous
3 mo
Mice
NO,, + influenza virus
caused a high incidence
of adenomatous prolifera-
tion of peripheral and
bronchial epithelial
cells
29
0.32
600
3 mo
Rats
Decreased conditioned
reflexes
83
0.36
680
7 days
Guinea Increased erythrocyte
Pigs D-2,3-diphosphoglycerate
84
0.4
740
4 hr/day
7 days
Guinea Increase in lung acid
Pigs phosphatase
85
0.4
740
Continuous
1 wk
Guinea Increase in protein of
Pigs lung lavage
12
0.5
940
6,18, or
24 hr/day
12 mo
Mice
Morphological effects in
alveoli
86
0.5
940
8 hr/day
7 days
Guinea Increase in serum LDH, CPK, 17,18
Pigs SCOT, SGT and cholinesterase,
and lung and plasma lysozyme.
Decrease in erythrocyte GSH
peroxidase. No change in
lung GSH peroxidase.
0.5
940
0.5
Continuous
14 days
1,OOONOx 8 hr/day
(mostly 180 days
(N02)
940 Continuous
30 - 45 days
Guinea
Pigs
Guinea
Pigs
Mice
Albumin and globulins 87
in urine
Nitrates and nitrites in 88
urine; slight increase in
serum cholesterol; decrease
in total serum lipids,
hepatic edema; increase in
urinary Mg and decrease in
liver and brain Mg
Morphological alterations 89,90
of tracheal mucosa and
cilia
(continued)
263
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TABLE 1 (continued)
Concentration of NO
3
ppm Hg/m
0.5 940
0.5 940
0.5 or 2 940 or
3,760
'
0.5 940
0.5 or 1 940 or
1,880
0.5 or 1 940 or
1,880
0.5 940
0.53 1 ,000
0.55- 1,030-
1.6 3,000
0.8 1,500
1 1 ,880
1-1.5 1,880
2,820
1 1 ,880
Time of
Exposure
5 days/wk
7 wk
Continuous
8 hr/day
4 mo
Continuous
with 1 hr
peaks of
2 ppm
5 days/wk
Continuous
12 mo
Continuous
1 yr, 5 mo
Continuous
1 yr, 6 mo
Continuous
or
intermittent
(7-8 hr/day)
180 days
8 hr/day
Continuous
5 wk
Continuous
2.75 yr
Continuous
2 wk
Continuous
1 mo
Continuous
6 mo
Species
Mice
Guinea
Pigs
Mice
Mice
Mice
Mice
Mice
Guinea
Pigs
Mice
Rats
Rabbits
Mice
Guinea
Pigs
Summary of Effects
Increase of injected
horseradish peroxidase in
lung
Decrease in plasma cholin-
esterase; erythrocyte or
lung GSH peroxidase
unchanged. Increase in
lung acid phosphatase and
plasma and lung lysozyme
Morphological alterations
of alveolar macrophages;
decreased serum neutralizing
antibody to influenza virus
immunization; changes in
serum immunoglobulins
At 10 days — damage to
clara cells and cilia and
alveolar edema.
At 35-40 days — bronchial
hyperplasia.
At 6 mo — fibrosis.
At 12 mo — bronchial
hyperplasia
No increase in lipofusin
or glutathione peroxidase
Growth reduced;
vitamin E improved growth
Increased susceptibility
to K. pneumoniae after 90
days continuous or 180 days
intermittent exposure
Alterations in several
serum enzymes
Cilia damaged; increased
mucus secretion
Increase in respiratory
rate
Decrease in lung lecithin
synthesis after 1 wk;less
marked depression after 2 wk
Hypertrophy of bronchiolar
epithelium after 1—3 mo.
After recovery from
exposure, lymphocyte infil-
tration
Inhibition of protein syn-
thesis; decrease in body
weight, total serum
proteins, and immunoglobulins
References
91
17,18
92,93
94,95
96
97
25
98
99
100,101
102
103
105
(continued)
264
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TABLE 1 (continued)
Concentration
ppm
1
of NO2
jUg/m3
1,880
Time of
Exposure
Continuous
493 days
Species Summary of Effects
Monkeys Immunization with monkey-
adapted influenza virus.
References
106
1.1
2,000
1.26
2,360
1.3-3 2,400-
5,200
1.5
2,800
2 or 3
3,760
5,600
3,760
3,760
3,760
3,760
8 hr/day
180 days
Guinea
Pigs
12 hr/day
3 mo.
2 hr/day
15 & 17 wk
Continuous
or
Intermittent
(7 hr/day,
7 days/wk)
3 hr
3 hr
Continuous
1-3 wk
Continuous
3 wk
Continuous
43 days
Rats, before
breeding
Rabbits
Mice
Mice
Mice
Guinea
Pigs
Guinea
Pigs
Rats
Increased serium neutraliz-
ing antibody titers at 93
days of exposure. No change
in hemagglutination inhibition
titers; no effect on hemato-
crit or hemoglobin; increased
leukocytes in blood.
Slight emphysema and thick-
ened bronchial and bronchio-
lar epithelium in virus-
challenged monkeys
Plasma and liver changes 107
decrease in albumin, sero-
mucoid, cholinesterase,
alanine and aspartate
transaminases, increase in
alpha and beta immuno-
globulins
No effect on fertility, 108
decrease in litter size
and neonatal weight, no
teratogenic effects
Increased leukocytes in 109
blood with decreased phago-
cytosis, decreased number
of erythrocytes
After 1 wk, increased sus- 24
ceptibility to S. pyogenes
aerosol greater in continu-
ous exposure group. After
2 wk, no significant differ-
ence between modes of
exposure
Increased susceptibility 21
to S. pyogenes aerosol in
mice exercising compared
to those not exercising
Increased susceptibility 22
to S. pyogenes aerosol.
Increased in number of lactic 110
acid dehydrogenase positive
lung cells (presumably
Type II cells) with time
of exposure
Type II cell hypertrophy 111
Between 72 hr - 7 days 26
increasing loss of cilia
and focal hyperplasia; by
14 days, cilia regenerated
and recovery was evident
at 21 days
(continued)
265
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TABLE 1 (continued)
Concentration of NO
, 3
ppm jUg/m
2 3,800
2 3,800
2.3 4,280
2.7 5,000
2.9 5,450
2.9 5,450
3 5,640
3.5 6,600
4-7 7,500-
1 3,000
5-50 9,400-
94,000
5 9,400
5 9,400
5 9,400
Time of
Exposure
Continuous
14 mo
Continuous
2yr
17 hr
8 wk
Continuous
20 days
24 hr/day
5 days/wk
9 mo
4 hr/day
4 days
Continuous
or
intermittent
(7 hr/day.
7 days/wk)
Continuous
14 days
3 hr
4 hr
4 hr/day
5 days/wk
2 mo
7.5 hr/day
5 days/wk
5.5 mo
Species
Rats and
Monkeys
Rats
Mice
Rats
Rats
Rats
Monkeys
Mice
Mice
Rabbits
Guinea
Pigs
Guinea
Pigs
Guinea
Pigs
Summary of Effects
Polycythemia with or
without NaCI. Hypertrophy
of bronchiolar epithelium
Increase in respiratory
rate; no change in resis-
tance or dynamic compliance
Decreased pulmonary bac-
tericidal activity (no
measurable effect at 1
ppm x 17 hr or 3.8 ppm x
4hr)
Decreased body weight
Decrease in linoleic and
linolenic acid of lung
lavage fluid
Decrease in lung compli-
ance and volume; increased
lung weight and decreased
total lung lipid; decreased
saturated fatty acid con-
tent of lung lavage fluid
and tissue; increased sur-
face tension of lung lavage
fluid
Thickening of basal laminar
and alveolar walls; inter-
stitial collagen
Increased susceptibility
to S. pyogenes aerosol with
increased duration of expos-
ure. No significant differ-
ence between modes of expos-
ure
Increase of injected radio-
labeled protein in lung
No measurable effect on
benzo (a)pyrene hydroxylase
activity of tracheal mucosa
Increase in respiratory
rate and decrease in tidal
volume
Increased lung tissue
serum antibodies
No increase in airflow
resistance
References
112
9
113
114
23
115
116
24
13
117
118
119
118
9,400
14-72hr
Mice
Increased lung protein
by radio-label method
(continued)
120
266
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TABLE 1 (continued)
Concentration of NO,.
Time of
Exposure
Species
Summary of Effects
References
ppm
5-10
5-10
10-0.1
jug/m
9,400
9,400
9,400-
18,800
9,400-
18,800
9,400
18,800
190
9,400
Continuous
1 wk
Continuous
2 mo
Continuous
90 days
Continuous
90 days
Continuous
133 days
6hr
7.5 hr/day
5 days/wk
5.5 mo
Rats Hyperplasia began by 3 wks 121
Monkeys Increased susceptibility 34
to K. pneumonias
Monkeys Infiltration of macrophages, 122
lymphocytes and some poly-
morphonuclear leukocytes;
hyperplasia of bronchiolar
epithelium and Type II cells
Monkeys No significant hematologi- 123
cal effects
Monkeys Immunization with mouse- 124
adapted influenza virus.
Initial depression in
serum neutralization liters
with return to normal by
133 days. No change in
hemagglutination inhibi-
tion liters or amnestic
response
Mice No chromosomal alterations 125
leukocytes or primary
sperm at ocytes
Guinea No increase in airflow 118
Pigs resistance
5-10
10-0.1
9,400
9,400
9,400
9,400-
18,800
5-10 9,400-
18,800
5 9,400
18,800
190
14-72 hr
Continuous
1 wk
Continuous
2 mo
Continuous
90 days
Continuous
90 days
Continuous
133 days
6hr
Mice
Rats
Monkeys
Monkeys
Monkeys
Monkeys
Mice
Increased lung protein 120
by radio-label method
Hyperplasia began by 3 wks 121
Increased susceptibility to 34
K. pneumonias
Infiltration of macrophages, 122
lymphocytes and some poly-
morphonuclear leukocytes;
hyperplasia of bronchiolar
epithelium and Type 11 cells
No significant hematologi- 123
cal effects
Immunization with mouse- 124
adapted influenza virus.
Initial depression in
serum neutralization
titers with return to
normal by 133 days.
No change in hema-
gglutination inhibition
titers or omnestic response
No chromosomal alterations 125
in leukocytes or primary
sperm atocytes
-------
ACID ANHYDRIDE
INJURY TO LUNG
TISSUE
CELL TYPES AFFECTED
results in a chemical reaction characterized by the formation of peroxidic products.
This is a devastating event in terms of the organization and properties of the cellular
membrane necessary to maintain the integrity of the cell. Many of the biological
effects can be ascribed to the peroxidation of cellular membranes, the most obvious
example of which is pulmonary edema, a commonly observed phenomenon on expo-
sure to high concentrations of N02- Inhaled N02 is rapidly taken up and distributed
throughout the lung as has been determined using short lived radiotracer studies with
13|\|O2 (6). A very significant fraction of N02 is retained in the lung. The fraction
which has been retained probably represents that NC>2 which is chemically reactive
with pulmonary tissue via peroxidation.
N02 is an acid anhydride and reacts with water vapor at ambient concentrations
in the air and more so at the increased temperature and humidity existing within the
respiratory system. The exact chemical species which reaches the pulmonary surface
to produce the observed lesions is most likely NC>2, but HIMO2 and perhaps NO may
be formed in the liquid lining the airways. HNC>2 and HNC>3 will be rapidly
neutralized by the biological substances dissolved in the liquid layer lining the airways
of the lung.
Despite the hydration of NOg by water vapor, a significant fraction of N02 is
not removed in the upper airways and penetrates deep within the lung to produce its
toxic effects. As a strong oxidant, IMC>2 may also oxidize small molecular weight
reducing substances and proteins within seconds to minutes. Reaction with unsat-
urated fatty acids to produce peroxidation is essentially instantaneous. It is not likely,
so far as is known, that NC>2 reaching the respiratory portions of the lung would be
able to penetrate the lung cells and attain a significant concentration within the blood.
Nitrate is formed as a consequence ot reactions with cellular constituents and has been
detected in the blood and urine of animals exposed to NC>2. Levels of nitrate attained
during N02 exposure are unlikely to induce biological responses of the nature which
have been observed. Because of the high reactivity of NC>2, the predominant response
observed on the inhalation of NC>2 is direct injury to the tissues of the lung. The
effects on organs distal to the lung are likely to result from the production of
secondary toxicants in the lung which are circulated to other parts of the body. A
direct proof of this hypothesis of circulating toxins following inhalation of N02
has not been found, but effects on organs other than the lung have been found. The
significance of these effects on other organs is not known as yet.
The major effect observed on IMO2 exposure is cellular injury and death which
occurs among specific cell types within the lung during a period of less than 24 hours
after inhalation (7). The magnitude and site of the injury resulting from N02 will
depend upon the concentration of NC>2 which was inhaled; therefore, the absolute
degree of response will depend upon both the rate and magnitude of respiration and
the N02 concentration. The moderate solubility of NC>2 in water and the inability of
the upper respiratory tract to remove all of the NO2 which is inhaled results in injury
to specific regions within the lung. At concentrations near those found in urban
environments, the region of the lung bounded by the terminal and respiratory
bronchioles and adjacent alveoli is that which is most affected (7,8,9,10). This region
represents the terminal portion of the lung and is intimately involved in the exchange
of oxygen and carbon dioxide. This is the region of the lung which is most essential
for the maintenance of life. Some differences may exist between man and rodents
because this region of the lung is proportionately much shorter in the rat than in man.
At high concentrations of NC>2, that is above 9,400jUg/m3 (5.5 ppm), segments
of the upper airways may be affected as well as those around the alveoli. As cells
are exposed to N02 and begin to die, protein and nucleic acid synthesis are stimulated
in the surviving stem cells and a wave of mitosis occurs which reaches its maximum at
about 48 hours during or after exposure. The type I cell of the lung (a thin,
squamous cell across which gases are exchanged) appears to be the most sensitive and
likely to be injured at lower concentrations than the type II cells (a cuboidal cell that
produces surfactant) (11). The nature of this injury can be sufficiently severe that the
cell dies, sloughs off, and leaves debris within the alveoli. Other cells in the upper
airway, such as ciliated cells, are similarly sensitive and may be replaced by other stem
cells known as Clara cells. These effects on the lung result in dramatic changes in its
structure and cell composition.
268
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BIOCHEMICAL INDICATORS
Biochemical indicators of this injury can be detected by a wide variety of means.
One of the most sensitive biochemical indicators of injury to these cells is a change in
cellular permeability which has been detected at concentrations as low as 752 /J.g/m3
(0.4 ppm) NO2 (12,13). At this concentration, plasma proteins or radiolabeled
albumin injected into the bloodstream of animals can be detected in the airways.
Under normal circumstances, such exudates do not occur and represent a major change
in the permeability of the cell to allow large protein molecules to escape into
the airway. Cells which are resident within the airway, such as the pulmonary
macrophage, are also damaged by inhaled N02- N02 damage can be detected as major
changes in the macrophage respiration (14,15). The death of macrophages may release
proteolytic enzymes which can produce further alterations in the organization and
morphology of the lung. Effects similar to those observed in vivo can be produced by
exposing isolated pulmonary macrophages to NO2 in vitro. The macrophage is
particularly sensitive to NO2 exposure. Paradoxically, biochemical parameters of injury
often return to normal or near normal values within a week or two of cessation of
exposure (16,17,18).
INFECTIVITY MODEL
LONG-TERM EXPOSURE
Pulmonary defenses against infectious agents are affected by short-term exposures
to N02- The infectivity model in which pollutant-exposed animals receive an aerosol of
live microbes has proven to be a particularly sensitive indicator of pulmonary injury
and has been responsible for the development of most of the data indicating toxicity
of NO2 at low concentrations and short times of exposure (19,20,21). Mortality from
exogenous infectious agents is influenced more in proportion to the concentration
of N02 than the duration of exposure. This observation is consistent with the
hypothetical temporal sequence of injury. Pulmonary damage occurs rapidly on
exposure to N02 but its effects may be observed much later, depending upon the
extent of damage and the system which has been used to measure the damage. The
infectivity model tends to be an integral of many of the defensive mechanisms of the
lung and, therefore, to reflect the overall damage which has occurred. Concentrations
as low as 4,700 /ag/m^ (2.5 ppm) may result in excess mortality from a single exposure
of only 3 hours (22). The injury of a 3-hour exposure appears to be repaired within
24 to 36 hours after exposure.
In Figure 2, a short-term exposure of constant duration has been given to an
animal and only one of the properties of intoxication is illustrated, the death of type I
cells. Increasing concentrations of N02 are illustrated in this figure on the z axis.
Thus, as the concentration of N02 is increased, the magnitude of cellular death
increases while the time at which cell death occurs is constant. The magnitude of cell
death is proportional to the logarithm of the concentration of NO2 which has been
inhaled. Increasing the total amount of N02 inhaled by manipulations in the respira-
tory pattern will likewise increase the magnitude of cell death, but not influence the
time at which cellular death occurs. Eventually, sufficient cells will be injured to
produce mortality during the peak wave of death of alveolar cells. Death through
respiratory insufficiency and pulmonary edema, however, does not occur at concentra-
tions achievable in the urban atmosphere. Concentrations greater than 47,000 M9/m^ or
25 ppm are necessary to achieve direct death. This is not to say, however, that severe
pulmonary damage is not achieved at lower concentrations near those which occur
regularly in urban areas.
The delay between the end of exposure and observation of biological effect
complicates the understanding of the effects of long-term exposure to N02- This is
especially so in cases resembling those that occur in the atmosphere where exposure to
NO2 may occur repeatedly over a short time period to relatively high concentrations.
Figure 3 illustrates the sequence of events which is hypothesized to occur on con-
tinuous long-term exposure to N02- The sequence of events is essentially similar to
that in short-term exposure. The chemical reactions between the inhaled NO2 and
cellular constituents are instantaneous and achieve a constant level throughout the
exposure. During the first 14 days of exposure, cell death and replacement of
pulmonary cells are the dominant features. This is expressed as a wave of mitosis or
cellular division which reaches its maximum about 48 hours after the onset of
exposure. The extent of cell death is illustrated in Figure 2 and is proportional to the
concentration of IMO2. Likewise, all of the other indicators of N02 damage so far
269
-------
U)
O
LU
cc
LU
00
m
O
24 48
7 14 30 60 (log scale)
hours days
TIME AFTER BEGINNING EXPOSURE
FIGURE 2—Proportionality between effect (cell death) and concentration of NC>2 during
a constant exposure period. The maximum in cell death is reached ~ 18 hours after exposure
and the extent is proportional to the dose (concentration x time)
l-
o
LU
LU
O
oc
LU
C/J
CO
O
I—I 1 I I
CHEMICAL REACTION
CELL DEATH
PULMONARY
FUNCTION
CHANGES
BIOCHEMICAL
INDICATORS
OF DEATH
AND
INJURY
REPLACEMENT OF DEAD
AND INJUREDCELLS
AND BIOCHEMICAL
INDICATORS OF REPAIR
INCREASED
SUSCEPTIBILITY TO
MICROORGANISMS
LEVATED
CELL
TURNOVER
INCIDENCE
OF EMPHYSEMA
-LIKE PATHOLOGY
HYPOTHETICA
TOLERANCE
1 -
(log scale)
hours
days
months
FIGURE 3—Temporal sequence of injury and repair hypothesized from continuous exposure
to NO2 as observed in experimental animals
270
-------
examined are dose dependent. The biochemical and physiological functional indicators
of damage change rapidly with injury and repair, reaching a relatively steady state
after about a week or two (17,18,23). Several enzymes have been detected which
are indicative of cellular injury at concentrations of N02 as low as 940 /ug/m3 or 0.5
ppm during the injurious phase of continuous exposure, that is greater than 7 days.
Pulmonary macrophages are aggregated within the lung and the degree of aggregation
has been estimated by a number of biochemical techniques. Again, the infectivity
model is highly sensitive to NC>2 exposure. The susceptibility to infection as measured
by this technique rises almost linearly during this period. The infectivity model has
been used to illustrate excess mortalities due to NC>2 exposure at concentrations
within the range of 940-2,820 jug/m3 or 0.5-1.5 ppm No2 (24,25,27,28).
ALTERATIONS OF LUNG
MORPHOLOGY
Long-term exposures to I\IC>2 also result in major alterations of lung morphology.
These are very difficult to interpret because of the slow gradation of response once the
initial phase of replacement of cells susceptible to NO2 has passed (9,26,27,28). The
development of an emphysema-like disease in experimental animals requires
considerable time as has been demonstrated in studies of rats. The development of
obstruction to airflow and distension and destruction of the alveolar tissue in
experimental animals requires considerable time. When compared to the life span, the
time required for damage in experimental animals is equivalent to that required for the
development of emphysema in man. The process of emphysema development on NC>2
exposure is indeed complex, but it is clear that the effects are interpretable in terms of
the changes in the cell populations and structural alterations concommitant to that. A
major pathologic change is an increase in the distance between the air space and the
capillary in the respirable or alveolar region of the lung (31-34). Other effects include
the loss of ciliated cells which are responsible for removing particles from the lung and
narrowing of the airways and alteration in the morphology of the cells lining the
junction between the respiratory segment and the mucous containing segment (26,28).
The cell type in the alveoli most sensitive to N02, the type I cells, are replaced by
type II cells, their progenitors, but the appearance of the type I cells maturing in the
presence of NO2 is significantly different from those in the absence of NO2 (31).
Other alterations in the lung include the appearance of collagen in areas which are
normally devoid of this fibrous protein and the aggregation of macrophages (28,32).
These effects have been observed in rats that have been exposed continuously to 3,760
(2 ppm) NO2 or greater.
VITAMIN E AND NO,
RESISTANCE AND RECOVERY
The fatty acid composition of the lung membranes has also been noted to change
during the exposure to NO2 (23). The mortality from continuous exposure to high
concentrations of NO2 is influenced by the level of vitamin E and other free radical
scavengers which are included in the diet (23). These observations support the
hypothesis that membrane damage by chemical oxidation of unsaturated fatty acids is
a major mechanism of toxicity of NO2- These changes in fatty acid composition of
the lung are accompanied by enzyme changes which in part may be protective and
aid in the destruction of the peroxidic products formed in the lung on N02 inhalation
(29). It should be emphasized that at no point is it possible to provide adequate levels
of vitamin E or other dietary factors that provide complete protection against N02- It
should be noted, however, that certain segments of the population may be unusually
sensitive to NO2 should their intake of vitamin E and other antioxidants be marginal.
The temporal sequence of events suggests that the response of the animal to
inhalation of N02 returns to near normal levels during continuous exposure. These
results are misleading since it has clearly been observed in long-term studies of rats that
the morphology of the lung has changed from its normal structure to that resembling
emphysema (9,26,27). This raises the question of tolerance to resistance and recovery
during continuous exposure. It is possible that, at some point, replacement of dead
and injured cells resulting from the continuous inhalation of NO2 may return to levels
equivalent to that found in clean air (26). Tolerant cells, as compared with naive cells,
may be more resistant to N02 because they are younger or because they may have
271
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produced a protective mechanism such as specific increases in enzymes capable of
degrading the secondary products formed on NO2 inhalation. Some enzymes such as
glutathione peroxidase, glutathione reductase, and glucose-6-phosphate dehydrogenase
in the rat may be increased as a protective mechanism (16), or they more likely may
reflect a proliferation of specific cells within the organ which contains higher concen-
trations. These cells are younger because they are dying and being replaced at a more
rapid rate, at levels in excess of those which occur normally in the lung in pollutant
free air. Not all species exhibit this protective induction of enzymes. For example,
the guinea pig, when exposed to 940 jug/m3 (0.5 ppm) NC>2 for 4 months failed to
develop higher levels of these potentially protective enzymes (17,18). Importantly,
when cultured lung cells are coated with a very thin layer of nutrients to resemble the
condition within the lung, direct exposure to NC>2 is highly toxic.
APPARENT ADAPTATION
TUMOR FORMATION
CUMULATIVE EFFECT
It is most likely that all cells are sensitive to relatively low concentrations of
NC>2 and that no adaptation in the true sense ever occurs. The apparent adaptation
that may been seen in pulmonary function measurements of people living in polluted
areas vs. those that live in nonpolluted areas may be artifactual in the sense that large
changes in pulmonary tissue may be necessary before permanent alterations may be
detected in pulmonary function. In other words, a major patho-physiological change
must occur before it is detected by these relatively insensitive pulmonary physiology
methods. Biochemical and morphological techniques are more sensitive, but so invasive
that they can only be used on experimental animals. In further support of the idea
that all cells are sensitive to concentrations of NC>2 which are easily attainable in
inhaled air, when rats have been exposed to 3,760 |itg/m3 or 2 ppm NO2 for long
periods of time and then exposed to an abrupt increase in concentration of N02, a
second wave of mitosis and subsequent alterations in biochemical, physiologic, and
morphologic indicators of cell damage occur in exactly the same temporal sequence
(33). Thus, although adaptation may appear to occur, the ultimate development of an
emphysema-like condition occurs in the rats on long-term exposure and they remain
sensitive to alterations to higher concentrations of NC^.
An important consideration has been the question of tumor formation of
malignant metaplasia due to NC>2 exposure. This concern comes about due to the
morphology of the lungs of animals which have been exposed to NO2- Because N02
produces a stimulation or rapid turnover of cells, a transient hyperplasia of the specific
type II lung cell and nonciliated bronchiolar cell is observed. Such a hyperplasia
represents a part of the natural repair mechanism. There is, however, no evidence to
indicate that such changes represent tumor- formation or malignant metaplasia. Thus,
there is no data to connect the inhalation of N02 with an increased incidence of cancer
at the present time.
We have come now to what is an important consideration of the effect of NC>2
on man. As was noted in the discussion of the effects of short-term exposure to NC>2,
the lag between exposure and biological effects. Such a cumulative effect has been
demonstrated using the infectivity model in mice which were exposed continuously or
intermittently (7 hr/day) to 2,820 /ug/m3 (1.5 ppm) N02 (24). After 2 weeks of
exposure, there was no difference in the pneumonia-related mortality between the
intermittent and continuous exposure groups. Therefore, for the intermittent NC>2
treatment, the intervening 17 hours between exposures apparently were inadequate for
complete recovery. Excess mortality could be shown at much lower concentrations on
continuous exposure. Ninety days of exposure to concentrations as low as 940 /ug/m3
(0.5 ppm) resulted in significant mortalities (25).
The effects of NC>2 inhalation on the susceptibility to bacterial infections is not
unique to the mouse. Other species of animals have been used including squirrel
monkeys (39). The common thread of these experiments has been that the infectivity
model is a good general indicator of damage by NO2- The direct extension of these
data to man is difficult, in part because of differences in anatomical structure of the
lung and in part because of differences in native and acquired immunity on the part of
man. These data then should be viewed in terms of their indication of toxicity rather
than in terms of their direct modeling of pulmonary infections in man.
272
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In terms of the probable temporal sequence of events, NO2 inhalation affects
almost all of the cell types within the lung. Depending, then, upon the concentration
of NO2, different cells will be affected in addition to those which are most susceptible
at lower concentrations. The mode of exposure, that is the rate and depth of respira-
tion, will also influence the specific cell types which are damaged. Because the rate of
chemical reaction of N02 with cell constituents is almost instantaneous when
compared to the time required for biological expression of injury, it may be expected
that the concentration of NO2 during a given exposure will have a greater effect on
determining the end point used to measure toxicity than would the duration of
exposure. Sensitive biochemical parameters are difficult to interpret because of the
need to correlate biochemical changes with pathological processes. They are viewed,
then, as indicators of death of specific cells or injury during the inhalation at the given
concentration and extent and duration of exposure.
OTHER AIR POLLUTANTS
CUMULATIVE
EFFECTS
HUMAN CLINICAL
STUDIES
Because of the universal toxicity of NC>2 to pulmonary cells, it is likely that
other air pollutants such as ozone, sulfuric acid, sulfur dioxide, and particulate matter
may injure the same cells within the lung as are injured by NC>2. In most cases,
following the simultaneous inhalation of NC>2 and other air pollutants, additive, rather
than synergistic effects, have been found. Tobacco smoking and occupational exposure
add very significantly to the toxicity of NC^. At present, the data are not sufficient
to provide a detailed evaluation of this important variable in the response of the
population. Because of the delay between the exposure to N02 and effect, the
sequence of exposures to air pollutants may be particularly important. Similar
responses have been observed with ozone and sulfuric acid.
Another area of possible toxicity may be the formation of nitroso compounds,
because nitrosamides and nitrosamines are known carcinogens. Nitrosamines and
nitrosamides have recently come into the public view through their formation in food-
stuffs containing nitrites. In this case, nitrite has been added to the foodstuffs to
prevent bacterial contamination and spoilage. Gas phase reactions between NC^ and
amines to form nitrosamines have been reported, and inhaled, injected or ingested
nitrosamines produce lung tumors in exposed animals. No evidence exists at the
moment that nitrosamines or nitrosamides are formed in ambient air from nitrogen
oxides, nor has it been demonstrated that they are formed in vivo in the lungs from
the inhalation of NC>2. Similarly, the role of inhaled nitrites and nitrates found in
atmospheric particles is unknown and should be studied further. A few experiments
indicate that inhaled nitrate produces biological effects through the release of hista-
mine and other intracellular hormones. Whether such effects occur in man is not
known. Continued surveillance of these important areas is needed.
While much remains to be learned about the toxicity of NC^, studies so far
conducted in animals indicate that the biological effects of N02 are likely to be
displaced from the time of exposure. As shown in Figures 1 through 3, this delay
between onset of symptoms and exposure to N02 may explain many of the con-
founding factors observed in epidemiologic data, but complicates further the question
of effects of transient episodes of high N02 concentrations in the atmosphere. It is
clear that the lowest concentration at which NC^, in particular, produces biological
effects of a reproducible magnitude so far detected in animals is 940 jug/m^ (0.5 ppm)
after repeated exposure. The observation of cumulative effects is especially important,
suggesting that under appropriate circumstances intermittent short-term exposure to
IM02 may eventually become equivalent to continuous long-term exposure. These
observations, when compared with the data which have been accumulated on the
long-term effects of N02, may be particularly pertinent to the potential toxicity of this
air pollutant to man. There is little doubt that the inhalation of N02 results in
toxicity, regardless of the species which has been exposed. Thus, animal experiments
are truly indicative of the hazard of this air pollutant to man.
A number of investigators have examined the effects of NC>2 in human
volunteers exposed for short periods of time under carefully controlled conditions.
Although sensory effects have been found by several researchers (35-39) these effects
are of uncertain significance. Therefore, the emphasis of this review will be on the
NO2 induced alterations of pulmonary functions. The summaries of the research
findings are on Table 2.
273
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TABLE 2
Effects of nitrogen dioxide in humans (clinical studies)
Concentration
ppm
0.05 NO
0.025 03
Time of
of NO Exposure
JUg/m
94 120 min
50
Subject Summary of Effects References
Healthy No effects on airway 41
resistance; increased
sensitivitv to a bron-
choconstrictor
(acetylcholine)
0.1
188
60 min
Asthmatics In 3 of 20 subjects —
increased specific
airway resistance; in
13 of 20 subjects -
increased sensitivity
to a broncho-constrictor
(carbachol)
51
0.3 NO 564 NO, 4 hr
0.50 9800
30 CO 45,900 CO
Healthy NO and CO did not alter
the effect of O expos-
ure on pulmonary function
54-56
0.5-5.0
940-9,400 15 min
Healthy Only highest cone.
caused effects:
decreased arterial par-
tial pressure of O , no
change alveolar partial
pressure O decreased
pulmonary diffusion
capacity for CO; with
exercise, increased
airway resistance
40,41,42
0.5-5
940—9,400 15 min
Bronchitics Effects only at 1.6 ppm
and above — increased
airway resistance. At
4—5 ppm, there was a
decreased in arterial
partial pressure of O_
and no change in alveolar
partial pressure of O0
40,42,43
0.5
940
120 min
Healthy, No change in pulmonary
brochitic, function
and asthmatics
50
0.61-1 1,147-1,880 120 min
Healthy No observed effects on 44,45,46
pulmonary function
0.7-2 1,317-3,766 10 min
Healthy Increased inspiratory
and expiratory flow
resistance
48
2.25-7.5 4,230-14,000 120 min
Healthy Increased airway resis-
tance which did not
increase as concentra-
tion was increased.
No change in arterial
or alveolar partial
pressure of O0
46
(continued)
274
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TABLE 2 (continued)
Concentration of NO
Time of
Exposure
Subject Summary of Effects References
2.5,5, 4,700,9,400 120min
or 7.5 or 14, 100
3.6 NO + 5,640, 11,230 Variable
NaCI
4-5
5.0
5 NO
0.1 O,
5 SO"
N02 + 1 ,400 Sequence
NaCI
7,520-9,400 10min
9,400 14 hr
9,400 NO 120 min
1960,
13, 000
SO,
Healthy At higher concentration 46
only, increased sensi-
tivity to a bronchocon-
strictor (acetylcholine)
Healthy No effect from NaCI 52
alone; increased airway
resistance caused by NO2
even greater when NaCI
included in exposure
Healthy Increased expiratory and 47
inspiratory flow resis-
tance greatest 30 min.
after exposure ended
Healthy Initial increase in air- 46
way resistance, followed
by partial recovery,
followed by even larger
increase in airways resis-
tance during exposure
Healthy SO_ and O., lengthened time 41
of recovery from increased
airway resistance
13, 160
10—12 min
Healthy Only some subjects showed
increased airway resistance
43
EFFECTS FROM
I\I02 ALONE
HEALTHY INDIVIDUALS
EXPOSED TO NO2
Much of this research has been conducted in the laboratory of von Nieding and
his colleagues (40,41) who have studied both healthy and bronchitic subjects.
Unfortunately, some of the techniques used for measurement of arterial partial oxygen
pressure, airway resistance, and plethysmography are different from the typical systems
used m this country. Because of this, it may not be possible to compare the data of
von Nieding et al. with those of American investigators. Nonetheless, the same technique
was used for a given study, and differences between functional measurements before and
after exposure were found by von Nieding. So even though the absolute values of these
changes may be subject to argument, the direction of the effects holds.
When von Nieding et al. studied 13 healthy individuals exposed for 15 minutes
to 940-9,400 jug/m^ (Q.5-5 ppm) NC>2, only the highest concentration was found to
cause alterations in pulmonary function. There was a decrease in the arterial partial
pressure of oxygen, but no change in the end-expiratory partial pressure of oxygen.
The net effect was an increase in the alveolar-arterial difference in partial pressure of
oxygen (AaDC^). Such a change implies a decrease in the transfer of oxygen across the
alveolar-capillary membrane. A similar effect was also found by von Nieding et al. (41)
when 11 healthy subjects were exposed for 2 hours to 9,400 ng/m^ (5 ppm) N02. The
subjects who had intermittent light exercise during exposure also exhibited increased
airway resistance, a finding that suggests a narrowing of airway diameter. In an
additional study by von Nieding (42), the pulmonary diffusion capacity for CO, which
275
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AIRWAY RESISTANCE
TIME COURSE OF NO2
RESPONSE
reflects transfer of gas between the airspaces and the blood, was significantly decreased
after a 15-minute exposure to 9,400 ng/m^ (5 ppm).
That individuals can differ in their sensitivity to NO2 was demonstrated by
Yokoyama (43) who exposed humans to concentrations of 13,161 Mg/m1-' (7 ppm) and
higher for 10-12 minutes while some subjects experienced increases in airway resistance
at 13,160 Mg/m3 (7 ppm), others were not affected by 30,080 ;ug/m3 (16 ppm).
Investigations by Hackney (44) and Folinsbee et al. (45) employed measures of
airway resistance and several additional functional endpoints. In these studies, exposure
to 1,880 M9/m3 (1 ppm) or 1,146.8 |Ug/m3 (0.61 ppm) for 2 hours caused no signifi-
cant effects on healthy individuals. A concentration of 1,880 /ig/m3 (1 ppm) was
also found to have no effect after 2 hours of exposure in a study performed by Beol
and Ulmer (46). However, at 4,230 jug/m3 (2.25 ppm) and above, significant increases
in airway resistance were observed which did not increase as concentration was increased
up to 14,000 /ig/m3 (7.5 ppm). There were no changes in the alveolar or arterial partial
pressure of oxygen. When exposure to 9,400 jug/m3 (5 ppm) was lengthened from 2
hours to 14 hours, there was an initial increase in arway resistance during the first 30
minutes which returned towards normal during the second hour. However, during the
continued exposure, even larger increases in airway resistance occurred bewteen 6 and
14 hours of exposure. When exposure was repeated on 2 consecutive days, the airway
resistance of the subjects was within normal values 10 hours after cessation of exposure.
In another phase of the experiment, the sensitivity of exposed healthy individuals to a
bronchoconstrictor agent (acetylcholine) was studied. After 2 hours of exposure to
14,100 M9/m3 (7.5 ppm), but not 4,700 or 9,400 M9/m3 (2.5 or 5 ppm) NO2, there was
an increased sensitivity to the drug. However, when the duration of exposure was
lengthened to 14 hours, 9,400 jUQ/m^ (5 ppm) NO2 did cause increased sensitivity to the
bronchoconstrictor agent.
In another study of the time course of the N02 response, Abe (47) showed that
the increases in expiratory and inspiratory flow resistance from a 10-minute exposure
to 7,520-9,400 jug/m3 (4-5 ppm) were maximal 30 minutes after exposure terminated.
At this time, compliance (a measure of lung distensibility) was also decreased.
Suzuki and Ishikawa (48) reported that healthy individuals exposed for 10 minutes
to 1,316-3,760 jug/m3 (0.7-2 ppm) had increased inspiratory and expiratory flow
resistance. Unfortunately, some information on the variability of the data was not
included in the report, and it was stated that NO2 levels varied during exposure. These
factors make an independent interpretation of the results difficult.
All the foregoing studies were made on healthy individuals. However, numerous
disease states exist which could alter an individual's response to NO2. Studies delving
into this complex problem of pollutant sensitivity have been performed by a few
investigators.
EFFECTS ON CHRONIC
BRONCHITIS
Von Nieding et al. (42) investigated the effects of a 15-minute exposure to 9,400
M9/m (5 ppm) N02 on chronic bronchitis. While there was no change in the alveolar
partial pressure of oxygen, the arterial partial pressure of oxygen did decrease, resulting
in an increased AaD02, as found in healthy subjects. Even though exposure was
continued for up to 60 minutes, further significant changes in these endpoints were not
found.
In additional studies with up to 88 chronic bronchitics, von Nieding et al. (40,49)
made observations on airway resistance as well as AaD02. The patients were exposed
for 15 minutes to between 940 and 9,400 /ug/m3 (0.5-5 ppm). No significant alterations
were found at < 2,820 |Ug/m3 (1.5 ppm). However, at > 3,008-9,400 (1.6-5 ppm), a
significant increase in airway resistance was observed and at 7,520-9,400 MS/m3 (4-5
ppm) there was a significant decrease in the arterial partial pressure of oxygen and an
increased AaDO2. On the other hand, after a 2-hour exposure to 940 /ug/m3 (0.5 ppm)
with light to medium exercise of healthy, bronchitic and asthmatic subjects, Kerr et al.
(50) found no significant changes in a number of pulmonary function parameters.
276
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ASTHMATICS EXPOSED
Orehek et al. (51) exposed 20 asthmatics to 188 /ug/m3 (0.1 ppm) N02 for 1
hour. In 3 of the 20 subjects, there were marked increases in specific airway resistance
after NO2 exposure. In another phase of the study, the sensitivity of the patients to a
bronchoconstrictor agent (carbachol) was studied. In 13 of the 20 exposed subjects,
there was an increased sensitivity to carbachol. This study is subject to controversy from
a statistical viewpoint and because an extremely sensitive technique (i.e., sensitivity to a
bronchoconstrictor agent) was employed. Although from this study it is not possible to
conclude that short-term exposure to 188 M9/m (0.1 Ppm) has an adverse effect, the
findings have public health implications which must be defined further by replication
of the study. In the Beil and Ulmer (46) von Nieding, et al. (41) and Orehek, et al. (51)
studies, cholinergic stimulation of the upper airways demonstrated the greatest airway
sensitivity to N02 inhalation. It could be argued that such stimulation is artifactual and
nonphysiologic. On the other hand, the role of cholinergic innervation and cholinergic
receptors in vasoactive hormone release and bronchial tone in man is well established.
Cholinergic pathways may be highly stimulated in atopic individuals, especially asthmatic
and bronchitic patients. Since atopy is a relatively common trait in man, these studies
bear confirmation and further study. NO2 may well cause the release of vasoactive
hormones, alter bronchial tone or increase mucus secretion. Such effects would tend to
exacerbate pre-existing disease and to accelerate the natural course of bronchitis and
asthma in man.
EFFECTS FROM IMO2 WITH
OTHER POLLUTANTS
INTERACTION OF GASES
In the natural environment, man is exposed to a complex mixture of pollutants.
The variety of this mixture with respect to the type of pollutants, concentrations, and
time patterns of occurrence make evaluation of the effects of pollutant combinations
inherently difficult. Several interesting relationships have been elucidated in the work
that has been done, but much remains to be understood.
Nakamura (52) investigated the effect of NO2 in combination with an aerosol of
NaCI (mean diameter 0.95 /urn) on airway resistance. The exposure regimen was varied
and involved a 5 minute exposure to 1,400 jug/m3 NaC1 along, a rest period of 10 to
15 minutes a 5 minute exposure to 5,640 or 11,280 ^g/m3 (3 or 6 ppm) NO2, a rest
period of 10 to 15 minutes and a final 5-minute exposure to a combination of the same
concentrations of NaCI and NO2. The NO2 exposure alone caused increased airway
resistance (at each concentration), whereas NaCI alone produced no effect. In combina-
tion, the increase in airway resistance was about twice that produced by the gas alone.
Schlipkoter and Brockhaus (53) showed that exposure to 9,024 ^9/m3 (4.8 ppm) N02
increased retention of inhaled dust. In the natural setting, if the inhaled dust were toxic,
it is likely that NO2 would increase its toxicity.
In an investigation of the interaction of gases, von Nieding et al. (41) exposed
healthy subjects for 2 hours to NO2 (9,400 ^ig/m3, 5 ppm) in combination with ozone
(196 _ug/m3, 0.1 ppm) or the same concentration of ozone plus sulfur dioxide (14,300
/ug/m , 5 ppm). The major effect of combining ozone or ozone plus sulfur dioxide with
N02 was to lengthen the time required for recovery from the increased airway
resistance, von Nieding et al. (41) also studied the effects of different concentrations of
these gases in combination. The 2-hour exposure of healthy subjects was to 94 jug/m3
(0.05 ppm) N02, 49 jug/m3 (0.025 ppm) 03 and 314 /ug/m3 (0.11 ppm) S02. There
was no effect on airway resistance or the AaD02. However, this exposure did increase
the individual's sensitivity to a bronchoconstrictor.
Different mixtures of gases were investigated by Hackney et al. (54-56). For 4 to
5 hours, healthy humans were exposed to Og, Og plus N02, or 03, NO2, and CO.
The following concentrations were employed: 980 j^g/m3 (0.5 ppm) 03, 564 /ug/m3
(0.3 ppm) NO2, and 34,500 ^g/m3 CO (30 ppm). The minimal alterations in pulmonary
function which occurred after 03 exposure were not increased by the addition of N02
or N02 plus CO.
The epidemiological studies demonstrate increased risk of acute respiratory disease
and diminished lung functions particularly among school children exposed to community
air containing N02, sulfur oxide, particulate matter, and in some cases photochemical
oxidants. In many cases, it is difficult to determine whether a given level of N02 was
277
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responsible for the observed health effects, or whether one of the other pollutants, alone
or in combination with NC^, was the causative agent. However, it is significant that the
reported studies directly support evidence from animal experiments and from controlled
human studies of increased risk of acute respiratory infection and alteration in normal
lung function. Interpretation of the data is complicated because of the complex variety
of pollutants constantly present in the ambient atmosphere and the difficulty in defining
actual exposure of the study population. Furthermore, those studies conducted before
1973 are of questionable validity due to a number of instrumental and analytical
difficulties inherent in the techniques used for measuring atmospheric concentrations of
NO2. Nevertheless, the existing data do not contradict the findings that pulmonary
effects are related to NC>2 exposure. These studies are described on Table 3.
PULMONARY TESTS
OF SCHOOL CHILDREN
The Chattanooga, Tennessee study conducted by Shy et al. (57-59), was designed
to detect changes in pulmonary function in school children living in a high, inter-
mediate, or low concentrations of NC>2. The results of these studies were of borderline
significance and consequently the association of impaired lung function with higher N02
concentration is not strongly supported. In these studies it is estimated that the annual
means of daily NO2 concentrations at the industrial area of high NC>2 was approxi-
mately 280 Atg/m^ (0.15 ppm). The validity of results of this study has been questioned
because direct measurement of NO2 could not be used and because significant
concentrations of sulfate and nitrate particulate seem likely to have been present. It is
possible that the particulate matter may have been a contributing cause of any observed
adverse effects measured. Several years later, Hasselblad, (60) performed an additional
study in the same areas of Chattanooga to investigate whether the exposure to air
pollutants during early life might have produced effects in children that persisted for a
number of years. Analysis of these data showed that the population living in the
intermediate and low pollution areas had no statistically significant impairment of
pulmonary function, suggesting that the effects observed earlier were reversible and that
recovery was essentially completed after 3 years.
PULMONARY TESTS
OF POLICEMEN
Speizer and Ferris, (61) studied 268 policemen in urban Boston who were exposed
to a spectrum of levels of automobile exhaust as traffic officers, patrol car officers, and
indoor clerical officers. The mean 24 hour NOo concentrations (as determined from
Q
1-hour sampling data using the Saltzman technique) were 100 jug/mj (0.055 ppm) in
the downtown urban area, and 75 /ug/m^ (0.04 ppm) in the suburban area. The test
results were standardized for age, height, and cigarette smoking habits. No differences
in pulmonary function were observed in these studies.
Cohen et al. (62) compared a variety of pulmonary functional tests in nonsmoking
Seventh Day Adventists living in Los Angeles with others of the same religious affiliation
living in San Diego. The average N02 concentration in the Los Angeles Basin was
96 Afg/m^ (0.05 ppm). In San Diego the levels were much lower. No group differences
in lung functions were detected in these studies.
JAPANESE TEST
RESULTS
Mogi et al. (63) and Yamazaki et al. (64) studied Japanese employees who worked
in areas where the N02 concentration could be classified as medium, light, or no
pollution. Mean NC>2 concentrations measured by the Saltzman method, ranged from
300-1,130 /ig/m-' (0.16-0.60 ppm). Test results obtained showed a decrease in
pulmonary function which did not correlate with the NO2 concentration in the working
area of the people. Kagawa et al. (65) and Kagawa and Toyama (66) studied the weekly
variation in pulmonary function of normal school children in Tokyo in relation to
variation in temperature and ambient concentrations of 03, NO, NO2, hydrocarbons,
S02, and particulate matter. In these studies, temperature was the factor most closely
correlated with variation in specific airway conductance and maximum expiratory flow
rate at 25 percent and 50 percent forced vital capacity. Negative correlations were
observed in sensitive children between 63 and specific airway conductance, and between
NO^, NO, SO2, and particulate matter at Vmax at 25 percent and 50 percent forced
vital capacity. The range of hourly N02 concentrations at the time of the lung function
tests, which was used for correlation during the period of study during the high
temperature season, was approximately 40-360 ^ig/m^ (0.02-0.19 ppm).
278
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EXPOSURE-HIGH AREAS
Using animal models there have been numerous reports that both continuous and
intermittent exposure to low concentrations of nitrogen dioxide can alter the host
respiratory defense mechanisms making the individual more susceptible to respiratory
infections. Based on this information, epidemiological studies have examined the effects
of IMO2 on acute respiratory illness. In a similar study, Poljak also reported that a
population residing within 1 Km of the chemical works in the Soviet Union had more
visits to the health clinic for respiratory, and other disorders than did a population living
more than 3 Km away. In this study also, the NC>2 was combined with high concentra-
tions of SC>2 and H 28(1)4 which may well have accounted for the observed respiratory
effects. Shy et al. (58, 59, 67) as a part of the Chattanooga, Tennessee study, evaluated
the frequency of acute respiratory disease in children and their parents living near a
large point source of nitrogen dioxide. Three populations were studied—one close to the
source with high N02 exposures and two with low N02 exposures. The total study
TABLE 3
Effects of nitrogen dioxide on humans (community studies)
A. Pulmonary function
Concentration
Measure
x annual 24 hr
high area
low area
1 hrx
high area
low area
x annual 24 hr
high area
low area
Est. 1 hr max
high area
low area
1 hr
Concentration of Summary of
NO2 Study Group Effects
ppm Mg/m^
0.055 +
0.035 SO2
0.04 +
0.014 SO2
0.14 to 0.3
0.06 to
0.09
0.05
0.01
0.26 to
0.51
0.1 2 to
0.23
0.02 to
0.19
103+ Policeman in No difference
92 SC>2 urban Boston in pulmonary
75 + 36 vs surburban function
SO2 areas
260 to 560
110 to 170
96 Nonsmokers in No difference in
43 Los Angeles vs pulmonary function
San Diego
480 to 960
205 to 430
40 to 360 11yrolds Temperature most
correlated with
References
61
62
65,66
pulmonary function
changes in sensitive
children. Specific air-
way conduction
negatively correlated
with NO2, NO, SO2
and particulates. At
high temperature, VMAX
and specific airway con-
ductance negatively
correlated with N02, SO2,
and particulates
Est. 1 hr max
high area
low area
0.75 to
1.5
0.4 to
0.8
1,400 to 2,800
750 to 1,500
children
Decreased forced
expiratory volume in
high concentration area.
Differences are of
borderline significance.
(continued)
57-59
279
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TABLE 3 (continued)
B. Acute and chronic respiratory disease
Concentration Concentration of
Measure N02
ppm /Jg/mJ
N02 0.31 to
0.64
SO2 0.12
H2 S04
High area 0.08-0.14
NO2 <0.01
SO2
suspended
sulfates (SS)
suspended
nitrates (SN)
total susp.
particles (TSP)
Intermediate
area
NO2 0.06
SO2 <0.01
SS
SN
TSP
Low area
NO2 0.03
SO2 0.01
SS
SN
TSP
Annual x
N02 0.05
03 0.046
NO2 0.023
Oo 0.038
580 to 1 ,200
225
400
150 to 282
<26
13-4
7-4
96-93
113
<26
10
3
62
56
26
10
2
62
96
92
42
76
Study Group
Adults within 1
Km of chemical
plant vs adults
>3 KM away from
plant
871 families
Families with
children born
1966-68
School children
born 1966-68
Nonsmokers in
Los Angeles
Nonsmokers in
San Diego
Summary of
Effects References
Subjects living close 67
to plant had 44% more
visits to health clinic
Respiratory illness 58,59,67,68
rate:
Children 22.1%
Siblings 18.8%
Mothers 14.2%
Fathers 12.1%
Bronchitis rate:
33.2% for children
in area > 3 yr.
Respiratory illness
rate:
Children 18%
Siblings 15.6%
Mothers 1 1 .8%
Fathers 8.8%
Bronchitis rate:
31.2% for children in area
>3yr,
Respiratory illness rate:
Children 20.1%
Siblings 17.0%
Mothers 12.3%
Fathers 9.6%
No difference in 76
prevalence of chronic
respiratory disease
(continued)
included 4,043 individuals. After adjusting for group differences in family size and
composition, the incidence of acute respiratory disease in the high exposure population
was found to be 19 percent higher than in the two comparison groups. In this study,
N02 concentrations were determined by the Jacob-Hochheiser method. This method of
analysis has been criticized for a variety of reasons, and thus the data were re-examined
using analysis obtained by the more acceptable Saltzman method. The reevaluation
indicated that the largest group differences in pollutant exposures were in the NC>2 and
suspended nitrate. However, it is known that h^SC^ and nitric acid aerosols were also
present in the atmosphere during this epidemiological study. As in all complex low-level
exposures, it is extremely difficult to identify which particular individual pollutant at
any concentration of exposure is the sole cause of the effect.
280
-------
TABLE 3 (continued)
Concentration
Measure
Median hr
high
N02
°3
low
NO2
°3
Annual x
NO2
Concentration of
NO7
»j
ppm jUg/mJ
0.07
0.07
0.035
0.02
0.042
130
137
65
39
79
Study Group
Office workers
in Los Angeles
vs San Franscisco
Women
Summary of
Effects
No difference in
prevalence of
chronic respiratory
disease
Bronchitis rate <5%
in areas having
References
77
69
<0.042 ppm NO2. High
cone, of TSP present
1/2 to 1 hr
N02
Annual x
NO2
so2
Annual x
6-70 to 12-70
high
intermediate
low
12-67to 11-68
high
intermediate
low
0.5 to 940 to
1 .0 1 ,880
0.25 to 470 to
0.5 940
0.04- 75-103
0.055
0.05 92
0.04 71
0.03 58
0.08- 15-282
0.15 117
0.06
0.06 117
Women cooking
with gas
stoves vs
electric
stoves
Children from
homes using
gas stoves vs
electric stoves
Policeman in
urban Boston
vs surburban
Adults
No increased
respiratory illness
Homes with gas
stoves: increased
bronchitis, coughing,
and wheezing
Small (not statistically
significant) increase in
chronic respiratory
disease of some
subgroups
in urban Boston
Prior exposure to higher
concentrations had no
influence on effects
observed
% prevalence of
chronic bronchitis
70
71
72
74
75
disease
early advanced
30 11
33 20
25 13
STUDY OF SCHOOL
CHILDREN
In a retrospective study in the same area, Pearlman et al. (68) determined the
frequency of lower respiratory disease among school children born between 1966 and
1969 in an area of high NC>2 exposure. The responses were validated by physicians and
hospital records. Bronchitis rates per hundred children were highest in the areas of
maximum NC>2 concentration. For children who had lived in the same neighborhood for
3 or more years, the bronchitis rate in the areas of high NC^ concentration were greater
than those for children living for comparable • periods in low concentration areas.
Bronchitis rates for children in the intermediate area were nearly as high as those deter-
mined from the children in the area of high NC^ exposure. However, the bronchitis
rate in children who had lived in the area for less than 2 years did not follow the
exposure gradient.
281
-------
CHRONIC BRONCHITIS
STUDY
INCREASED ILLNESS
RATES
RESPIRATORY DISEASE
AND POPULATION
EXPOSURE
A study (69) of chronic bronchitis among Japanese housewives living in six
localities throughout Japan was conducted during the winter of 1970 and 1971. The
prevalence rate of chronic bronchitis was found to exceed 5 percent only in those areas
where the annual N02 concentration was 79 ng/m3 (0.042 ppm) or above. This
Japanese study was confounded by high total suspended particulates ranging from 2-6
times the United States primary standard, which could not be appropriately disentangled
from the effects of N02 alone.
Investigators from the Environmental Protection Agency (70) compared the
incidence of acute respiratory disease among housewives cooking with either gas or
electric stoves. Because of the high flame temperatures, the gas stove produced peak
concentrations of NC>2 as high as 940 jug/m^ (0.5 ppm) for durations of 1/2 to 1 hour
each time the gas stove was used in preparing meals. Electric stoves which operate at
lower temperatures do not form N02. In this comparative study, no difference in
incidence of respiratory disease was evident. A similar study by Mitchell et al. (71)
determined the incidence of respiratory disease in Ohio middleclass families with gas
stoves and electric stoves. Health data were obtained through biweekly telephone calls
for one year. No difference in respiratory disease was detected. In these studies, the
reported peak NO2 concentration in homes with gas stoves was as much as eight times
higher than the 24 hours means, and sometimes exceeded 1,900 M9/m^ (1 ppm).
A study of children in England and Scotland showed increased illness rates in
those living in homes with gas stoves compared with children from homes with electric
stoves (72). In this study, the analysis of data collected took account of the individual's
social class, age, population density, family size, crowding in the homes, outdoor level of
smoke and sulfur dioxide, and type of fuel used for heating in the home. However, the
smoking habits of the parents were not determined. The prevalence of bronchitis in the
homes using gas stoves was 5.7 percent and 4.7 percent for boys and girls, respectively.
In the homes with the electric stoves, the prevalence was 3.1 percent and 2 percent. It
was also noted that girls in the homes of gas stoves had a significantly higher prevalence
rate for morning cough and for wheeze. The investigators concluded that the elevated
levels of NOX might have caused the increased respiratory illness.
These studies provide evidence of increased occurrence of acute illness in areas in
which ambient concentrations of NO2 are high. The data suggest that peak hourly con-
centrations in the range of 470-1,880 jug/m^ (0.25-1.0 ppm) may be associated with the
occurrence of a greater number of respiratory illnesses. However, it should be noted that
the epidemiological studies or acute respiratory disease and populations exposed for
long periods to elevated N02 concentrations, provide evidence to support the animal
data on N02, which indicates that NO2 can impair resistance to respiratory infections.
However, in many of these studies, it is difficult to determine whether a given con-
centration of N02 was responsible for the observed health effects or whether one of
the other pollutants, alone or in combination was the causative agent. In many
instances, the concentration of materials such as suspended sulfates or nitrates were not
monitored, and the concentration of potentially toxic acids (such as nitrous and nitric,
sulfurous and sulfuric) that represent the intermediate products of the transformation
also were not determined. These other pollutants also could have attributed to the
adverse health effects observed.
A few epidemiological studies concerned with the relationship between chronic
respiratory disease prevalence and population exposures to NO2 have also been con-
ducted. One such study (69) conducted in 1970 and 1971 examined young Japanese
housewives and these investigators found that the prevalence of chronic bronchitis
exceeded 5 percent in those areas where the overall NO2 concentration was 70 ng/m^
(0.042 ppm). However, at the time of this study, there were also extremely high levels
of total suspended particulate which may have contributed to the observed effect. Fujita
et al. (73) compared the prevalence rate of chronic bronchitis among postal workers in
1962 vs. 1967 and reported that there was an overall increase rate of chronic bronchitis
in 1967 vs. 1962. These researchers believed that the concentration of NO2 was higher
in the later years, however there were no data to substantiate this claim. The aerometric
data available for this study was insufficient to show any meaningful association
between the prevalence of chronic bronchitis and any single pollutant such as N02.
282
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FOOT PATROL/
PATROL CAR STUDY
In Boston, Speizer and Ferris (74) compared the prevalence of chronic respiratory
disease among policemen who patrolled on foot in congested business areas of Boston
with that of suburban patrol car officers. The exposure of each group to N02 was
determined at several work locations for the central city officers as well as the officers
in the patrol cars. The annual mean pollution levels, based on hourly samples, were 103
jug/m3 (0.055 ppm) NO2 and 90 ;ug/m3 (0.05 ppm) S02 for the urban area. The
suburban area averaged 75 M9/m3 (0.04 ppm) NO2 and 26 /jg/m3 (0.01 ppm) S02. The
urban policemen who had spent more time in heavy traffic exhibited a small, but not
significant, increase in chronic respiratory disease in nonsmokers and current smokers.
No effect was seen in exsmokers.
CIGARETTE SMOKING
CONCLUSIONS
A number of other studies also failed to establish an association between
prevalence of chronic bronchitis and exposure to concentration of N02 in the ambient
environment. Chapman et al. (75) studied the prevalence of chronic bronchitis in 3,500
parents of high school children living in three different areas of Chattanooga. In this test
area, higher NO2 concentrations had been present during the years of 1966 to 1969
than were present at the time of this study (1970). These authors failed to find any
correlation between the concentration data for either period and the prevalence of
chronic respiratory illness in the studied populations. Similarly, Cohen et al. (76) also
found no difference in the prevalence of chronic respiratory disease between the non-
smoking population in San Diego as compared with a similar population in Los Angeles.
The Los Angeles group was exposed to levels of NO2 between 90 and lOO^g/m3 (0.05
ppm) plus an oxidant level of about 90 M9/m3 (0.045 ppm); the San Diego group was
exposed to lower levels of N02 of approximately 40 M9/m3 (0.02 ppm) and concen-
trations of oxidant of approximately 76 jug/m3 (0.04 ppm).
Linn et al. (77) suggested that cigarette smoking was more significant than was
Los Angeles air pollution in the development of chronic respiratory illness. These
investigators compared Los Angeles women exposed to an hourly NO2 concentration of
130 /ig/m3 (0.07 ppm) with San Francisco women where the hourly N02 concentration
was 65 Mg/m3 (0.35 ppm). The medium hourly oxidant level in these two areas were
0.07 and 0.02 ppm, respectively.
In addition to these epidemiological studies, there are a number of recorded
accidental and occupational exposures of workers to high concentrations of N02 or
other oxides of nitrogen. The exposures to high concentrations of N02 have
demonstrated and confirmed the potential hazard associated with short-term exposure
to NO2. Very high concentrations in the range of 560,000 jug/m3 (300 ppm) or higher
are likely to result in rapid death. At lower levels, acute exposure to concentrations
greater than 50,000 ng/m^ (25 ppm) N02 causes severe respiratory distress consisting
of cough, dyspnea and a tightness of the chest and respiratory tract caused by acute
bronchitis or pulmonary edema. In such acute exposures, the individuals may recover
without further complications. However, if the exposure duration is long enough more
intense symptoms may occur after a latency period of 2 weeks to 3 weeks. When the
symptoms are not sufficiently severe to cause death, the individuals apparently recover
fully. For more detail concerning accidental and occupational exposure studies, the
reader is referred to the following references: Lowry and Schuman (78); Grayson (79);
Gregory et al. (80); and Milne (81).
An array of health effects is caused by exposure to N02. Both the type and
magnitude of the effect are affected by the concentration, time, and mode of exposure,
the experimental subject (animal or man), pre-existing disease state, and presence of
additional pollutants. While it appears that the lung is the primary target organ, other
body systems cannot be assumed to be safe from potential hazard, since only limited
studies on systemic effects have been performed.
In quantitative terms, the lowest concentration at which either biochemical
changes or the reduction in resistance to infectivity can be detected in experimental
animals is 940 /ig/m3 (0.5 ppm) IM02 for 3 weeks to 3 months. Time needed for
recovery from a single short-term exposure to N02 will depend upon the concentration
and duration of exposure to N02 and the endpoint measured. It is likely that the
recovery period is greater than 17 hours, since this time resulted in an eventual
283
-------
accumulative effect of NO2 exposure. Such an observation has obvious implications on
the time between exposures of the population at large or the cyclical nature of N02
episodes. The temporal sequence of N02 toxicity in man is unknown, but is likely to be
very similar to that found in animals because the same cell types exist in animals as in
human lungs and because injured cells must be renewed. The rate of renewal is basically
the same between animal and human lung cells. It is not possible at the present time to
resolve the question of true adaptation, but it does not seem likely that adaptation in
the true sense of the word (i.e. protection from further deleterious effects qr reversal
of pre-existing injury) could occur in the presence of occupational exposures or social
habits such as cigarette smoking. Other factors existing in the population at large are
likely to influence the overall toxicity of NC>2. Not the least among these are the
demonstrated effects of diet and vitamin E on toxicity which has already been observed
in animals and may likewise occur in man. We would be remiss in not considering the
toxicity of the other oxides of nitrogen which exist in ambient air. Of great concern is
nitric oxide or NO. To date, NO has been found to be much less toxic than N02, but
it may have important biochemical effects which are expressed through the changes in
the intracellular concentration of cyclic nucleotides. These cyclic nucleotides represent
the second hormonal messengers which regulate important cell processes. NO affects
cyclic GMP which is an important intracellular hormone regulating the processes such as
the expulsion of hormones or exocytosis. Alterations in intracellular levels of this
hormone also may cause destabilization of cell membrane. Because of the seriousness of
the effects, continued observation and cognizance of the potential toxicity of NO to
man is highly important.
CLINICAL STUDIES In controlled human clinical studies, only measurements of pulmonary function
and sensory responses have been made. Upon N02 exposure, the most consistent finding
was increased airway resistance which was found to occur in healthy individuals after a
short exposure (10 min) to 1,300 jug/m3 (0.7 ppm). Bronchitics exhibited a similar
response to 3,000 jUg/m3 (1.6 ppm) NO2. Asthmatics exhibited increased sensitivity to a
bronchoconstricting drug after a 1 hr exposure to 190 jug/m3 (0.1 ppm). Unfortunately,
these concentrations cannot be directly compared to form an absolute ranking on classes
of susceptible humans. To accurately rank susceptible groups, more controlled studies
are required.
Because of the difficulty of characterizing pollutant exposure or utilizing optimal
methods (i.e. consideration of confounding factors like smoking), most of the epi-
demiological studies performed are not useful in evaluating the health effect of N02-
However, in a few studies, health effects such as alterations of pulmonary function on
increased risk of acute respiratory disease have been correlated with NO2 exposure.
From the available data, it can be concluded that NO2 is toxic to man. Great
controversy surrounds the area of the definition and relative importance of toxic effects
versus reversible health effects. The lowest concentration which causes health effects in
man is also argued. However, it is still clear that the public must be protected from N02
and that meeting this goal is essential.
284
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panel
discussion
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HEALTH EFFECTS PANEL DISCUSSION
Elizabeth Anderson, Ph.D.
Roy E. Albert, Ph.D.
Carcinogen Assessment Group
U.S. Environmental Protection Agency
Richard Bates, Ph.D.
National Institute of Environmental Health Sciences
National Institute of Health
Jean French, Dr. PH
National Institute of Occupational Safety and Health
Department of Health, Education and Welfare
Cyril Comar, Ph.D.
Environmental Assessment Department
Electric Power Research Institute
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DR. ANDERSON: Can risk assessment methodologies be developed that define and
accurately predict the effects of expanded coal use on the public health? This is the
question for discussion before this panel.
DR. ALBERT: My answer to that question is a qualified yes. For 3 years, EPA has
been in the business of risk assessment for carcinogens and during that time has looked
at about 50-odd agents. Guidelines for risk assessment have been set up for 3 years.
The assessment process is two-pronged: qualitative and quantitative. Qualitative assess-
ment is a judgment about the likelihood of an agent being a carcinogen and quantita-
tive assessment is a judgment of how much cancer the agent is likely to produce. We
take a weight-of-evidence approach for qualitative judgment, and we need exposure
estimates and the use of extrapolation models based on either human or animal data
for quantitative assessment. Quantitative assessments are made in terms of the average
individuaJ risk, given the exposure levels, the maximum level of risk, and the number
of cancer cases that might occur, either per year or over the lifetime of the individuals.
Quantitative assessment is the more controversial of the two. The scientific foundation
for either qualitative or quantitative risk assessments is actually not very strong. The
basis for qualitative assessment is about 25 agents that are known to cause cancer in
humans. All except perhaps one or two have been shown to cause cancer in animals,
particularly in rodents. So the use of rodents is justified on that basis. We do not have
information on the magnitude of the problem of false positives, that is, when animal
tests show positive but the agent is really not a human carcinogen. We have a paucity
of information on carcinogenic responses in humans.
Everybody seems to be happy with the qualitative judgment. Very few people
are happy about quantitative assessment. The EPA guidelines describe this assessment
as a crude, ballpark affair, designed to give the decisionmaker a feel for the magnitude
of the hazard. We can check only about half a dozen examples of animal data in
predicting human responses. Of these, three show that responses in animals and
humans are essentially the same. The other three indicate that animals overpredict
the responses in humans. I think it will be possible to develop a better, sounder basis
for the use of quantitative assessment, at least in terms of demonstrating that animals
do not underestimate human risk, which will be of considerable benefit. My personal
view is that there are no alternatives to quantitative assessments as long as one recog-
nizes their limitations. We are dealing with a major public health problem; that is,
setting up sensible, reasonable controls for a large number of environmental carcino-
gens. We cannot say we will control every one of them down to the vanishing point
because there are real uncertainties concerning how much one is justified in spending
on the individual agent. In this sense, I believe that the quantitative assessment, crude
as it is, can be of some use.
Again, the answer to the question of whether risk assessment methodologies
can be developed to define and accurately predict is a qualified yes.
DR. BATES: You would not want unanimity, would you? My answer is a qualified
no. That is easy for me to say because of the inclusion of the phrase accurately predict
and what is meant by accurately. In the business of risk assessment, if we can come
within two orders of magnitude, we are doing pretty well, but I do not think we can
do that very often. The Can risk assessment methodologies be developed part of this
question implies that they cannot be developed now, but in the future, which is
essentially my answer: We cannot now accurately develop them. We may, as Dr.
Legator said, be able to put things within broad ballparks. And, after all, that is the
kind of thing that really forms the justification that Dr. Albert gave. If we need to set
priorities for our actions, we can do that by putting risk estimations within broad
ranges. We do not have to get down to absolute numbers in order to do so.
Let me expand a bit. Dr. Albert talked only about carcinogenicity and that
has been where most of my professional life has been spent. It is difficult for a lot of
us in this field to remember that man does not die by cancer alone. In our society
there are quite a variety of toxic phenomena that are energy-related or otherwise. In
acute toxicity any organ may be affected within a short time after exposure, but in
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chronic toxicity, the effect is not seen initially, but eventually the effect is a degenera-
tive change: carcinogenicity, mutagenicity, teratogenicity, behavior, hypersensitivity, or
any variety of others. How good are our assay systems for identifying these effects,
even on a qualitative basis? The answer varies greatly. They are probably pretty good
for acute toxicity; we can identify acute effects fairly well. And experience has shown
that if we put in some sort of a safety factor of 100, we do not get into too much
trouble in our society. We have studied carcinogenicity longer than we have studied the
other effects. Our models for carcinogenicity are probably pretty good qualitatively
but not quantitatively. The quantitative effects vary according to the genetics of
individuals within species and the genetic differences between species. Within at least
three orders of magnitude according to one experiment and two orders of magnitude
according to many experiments, sensitivity is also modified by variations in diet and
chemical or other environmental exposures. There is complexity here. It extends to
some of our other toxic phenomenta but has not been studied as extensively as for
carcinogenicity. Dr. Legator thought that the mutagenicity tests are pretty good
qualitatively but not quantitatively. I would agree with that.
Why was it that thalidomide, probably the worst chemical teratogen identified
in humans, was not identified with the usual experimental rodents? This raises ques-
tions about how good our qualitative assays are for teratogenicity. There are some
who will disagree, but I think we have a way to go. Our assay systems do not take
into consideration the effects of diet or of combined exposures, which our human
data on chronic degenerative effects, such as atherosclerosis, immunologic defects,
and so forth, say are important. I am not at all convinced that we have very good
qualitative assays for chronic toxicity.
After we ask how good the experimental model is, we then have to ask about
our extrapolation procedures. These give widely different answers as we go to much
lower doses than those in which the experiments are done. And, as I alluded earlier,
we do not really take into consideration the vast effects that synergisms can cause.
There are research ways out of this, and if we had more time I would discuss them.
But we are talking about our present energy needs and not those that are 2 or 3
decades from now. Dr. Legator talked about studies of cytologic and biochemical
changes in human beings who are actually exposed and affected. This is one very
useful approach that needs to be followed up to a greater extent in the future and
that may get us out of this bind.
DR. COMAR: My answer is that the question is only partially relevant. We have a
great capacity to identify and publicize risks, although we need to do a lot more
research. But we do not know what to do with the answers when we get them and
that is where we will need more research of a different kind. We would all agree,
I think, that environmental decisionmaking tends primarily and necessarily to be
political. It is influenced, as it should be, by public pressures and by public perceptions
of risk rather than by the risk itself. With a considerable degree of truth, it has been
said that decisions about technological options tend to be based not on the number of
people who are killed or who are harmed or who are suffering, but on the number of
people who are frightened. Thus, for example, we are about to lose our nuclear option,
an option in which probably no one has been killed, probably no one has been
harmed, at least in the general population, but in which lots of people have been
frightened. We are about to embrace a coal option where lots of people have been
killed or suffer misery, at least in the coal mines, but no one is frightened. I suppose
in a political system this makes sense because dead people do not vote, but frightened
people do.
We need not only to estimate and define risk, but to be sure that public percep-
tion and risk are reconciled. We know that the public is increasingly well-informed
about risks. They are exhorted and concerned, and they exhibit anxiety. There is great
sensitivity. And I suggest that what we need more than anything else is to start re-
search to establish the extent to which any observed effects have an adverse effect
on the public health or on the well-being of individuals. I think that, if we look hard
enough at almost any substance and agent that we expose ourselves to—and coal
burning is a good example-we are going to be able to identify effects from many of
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them. It is very clear in our society that, if only a few substances are harmful, we can
isolate ourselves from them and reduce risk to zero. But when most substances are
harmful and only a few are safe, then zero risk is just unattainable if we are going to
carry on the way of life that we now have. What we need then is a new research
approach that parallels the estimation of risk with the estimation of real adverse
effects. Of course, this is going to lead us eventually to another matter, which is very
difficult. That is the whole business of risk acceptance. And, again, we really have not
developed in our society an institutional mechanism, or even a traditional mechanism,
to deal with risk acceptance. This is something that could be talked about for a long
time.
What we do is get along with determinations made by individuals, by self-
appointed public interest groups, by judges, by Congressmen, by regulators. We
have all of these people with their own narrow focus-making judgments about risk
acceptance. And somehow we have to have a holistic view of risk acceptance. In the
meantime, I and others have suggested the possibility of some sort of a de minimis
approach, not that one would be presumptuous enough to say how much risk anyone
else should accept, but it seems to me there are some levels of risk that we just should
not worry about. Instead we should be worrying about other competing risks that are
really going to have an effect on our well-being and on the well-being of our society.
DR. FRENCH: Although it has been said that the greatest impact on energy
development will take place in the occupational setting, / cannot give you an estimate
of what that risk will be. How can one assess the implication of a positive salmonella
test with something like benzopyrene and then relate it to the risk of a miner in a coal
mine who may or may not be a smoker, who may or may not be in a compromised
nutritional status, and who may also be in a mine where a diesel car is used as part
of the technology to get the coal out? An additional factor is whether that miner is
short or tall. A recent finding from one of our epidemiologic studies of uranium miners
showed a significantly greater risk of cancer of the lung in short miners than in tall
ones. That finding illustrates the complexity of the problem. It was thought that
maybe the shorter miner had a greater intake of dust, that the dust settled. But our
industrial hygiene studies did not bear this out. It has been hypothesized that possibly
the shorter miner, with shorter arms, must work harder to dig out the coal and there-
fore has a greater uptake. I will leave that to your good judgment. This just shows
the complexity of the problem, and I do not think we should underestimate that
complexity.
Because the problem is complex does not mean that we should shy away from it.
In order to get on top of it, it will be necessary to undertake a very integrated holistic
research program. We at NIOSH are trying to identify evolving technologies and what
some of the problems might be as they come about. For example, we are working
with DOD in looking at processes that might be used for the fluidized bed. We are
trying to identify problem areas, so that our control technology can work along with
people as they develop these various approaches. We want effective controls as the
technology develops and not after it is established and we have to correct problems
that have been ignored. We are also looking at interactions such as the effect of SC>2
combined with lead and cadmium in some of our animal models because this is the
situation in the real world. The worker out there is not exposed to a single agent. He
is exposed to a complex milieu of chemicals and physical factors such as temperature.
We are also looking at nutritional deficiencies in animals and then administering
complex chemicals to observe the effects.
I cannot stress enough the importance of epidemiology. All too often people
dwell on the limitations of epidemiology but not quite so strongly on the limitations
of toxicology, but they are there. We must have all of these approaches going on con-
currently, building one on another, and we must piece together the information from
these various areas. When we fill in all the boxes, we will then have a much better
method of coming up with some reasonable assessment of risk.
A friend of mine once said that we very often take more prudent controls when
our body of knowledge is lacking, because we really do not know. Thus, in order to
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protect the public health, in order to be prudent, we must lean toward a more strin-
gent approach. Going from a very simple, short-term in vitro test and extrapolating
to the universe can lead only to a very dangerous risk assessment. We need first to
identify the complexities that must be addressed in our research effort, and then put
them together for use in a common sense manner.
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questions
& answers
Robert E. Thomason
Occidental Oil Shale, Inc.
E. V. Anderson
Johnson and Higgins
Carl A. Gosline
Manufacturers' Chemical Association
Bill Eberle
Lockheed
COMMENT
I have some remarks on appropriate risk analysis.
I am associated with oil shale development in western
Colorado. Probably the biggest risk that I am going to
take is running to the airport after I give this message.
But I am very sensitive to the words "cancer" and
"death."
For the benefit of the public, researchers must
put their comments into perspective. They should be
very careful to make comparisons between apples and
apples, not apples and garlic. Synthetic fuels should be
compared with the products of the petroleum refining
industry. There are considerable differences between
synthetic fuels and unrefined crude products. Oil shale
differs according to the process that is wed to extract
it.
With respect to Dr. Legator's research, biologists
can make some additional contributions to the remarks
and add the categories of control of hygiene and health
education to his conclusions. Also, with respect to Dr.
Clusen's remarks, Occidental is anxious to get DOE,
EPA, and industry much closer together than they are
now. It is interesting to note that DOE is doing some
bioassay research that categorizes oil shale as a little
more noxious than was identified by Dr. Holland.
In conclusion, in reference to the present fuel
shortage and supply, I am annoyed when I have to
siphon gas from one of my automobiles into the other
because I could not get a timely place in a gasoline
line. It is important that researchers give the public
the whole story, the specifics behind their investigation,
so that we can do a more careful analysis and reach
more appropriate conclusions.
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QUESTION
How do the potential risks of more nuclear develop-
ment with enclosed equipment compare with more lique-
fied coal, on a scale of 1 million times the coke oven
scale that we now have trouble with?
RESPONSE: Dr. Cyril Comar (Electric Power Research
Institute)
Many analyses show that on a calculated basis, the
normal operations of nuclear power are much more
benign than conventional coal combustion. This applies
especially to the situation you have raised.
With regard to nuclear power, however, there are
other considerations, such as a different pattern of effect.
As a society, we have not yet come to grips with the low-
probability, highly catastrophic accident. That is an issue
that must be taken into account. With nuclear power,
people always have the nagging uncertainty that some-
thing may happen in the future. When a dam breaks
and people are killed, it is over and we recover from it.
But it is that nagging uncertainty that bothers people. In
that comparison, there must be a consideration of our
psychological approach.
QUESTION
As this is an R&D conference, I would like to ask
a question with regard to risk assessment. Assuming we
could arrive at a two-orders-of-magnitude statement of
risk, using the holistic approach, how does the regulatory
process manage that information, particularly with regard
to extreme probabilities that nobody really believes will
happen? Public policy can no longer be set on the basis
of myth or fright concerning outcomes possible in some
finite, mathematical sense. Ten years ago we were told
that by this summer the oceans would be dead. That
environmental myth, based on misinterpretation of
limited laboratory data, spread around the world. A
decade later, we realize, in a different context, that this
is not a zero-risk world. If we can define the risk, how do
we apply the knowledge to the available resources, recog-
nizing all the problems in the environmental area?
RESPONSE: Dr. Roy E. Albert (EPA)
The points of view have not been thought through;
the methods of handling risk assessment products have
not been adopted in a uniform fashion. This area needs
development. Quantitative assessment has been used to
help make regulatory decisions. This is only one of many
components that go into decisionmaking. For example,
in the case of one pesticide, the studies were inadequate.
It was decided, on the basis of a risk assessment that
proved to be exceedingly low, that it would not be
unduly hazardous to use the pesticide for another year or
two while additional testing was done. In another
instance, the permissible limit of contamination of fish by
a pesticide was set far higher than was commensurate
with other pesticides or other carcinogen regulatory
302
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actions. Quantitative assessment has also shown that
subpopulations exposed to a carcinogen may have an
unduly high level of risk, even though the risk to the
general population is small. Thus, although we have begun
to see reasonable uses of quantitative assessments, we still
have a long way to go to formulate a solid and rational
basis for dealing with these assessments.
RESPONSE: Dr. Richard Bates (NIH)
That is a very difficult question. We deal with
risks from different sources of exposure quite differently.
There is a wide variety of regulatory laws. They deal
with risk quite differently and require different levels
of safety. But we have not resolved the social aspects of
this question. The science is in its infancy. We are now
asking questions about the environment and the effects
of chemicals in the environment on ourselves and on
other species. In the past, people polluted the water,
air, and land, but there were few people and industry
was small, so we thought we got away with it. The
effect was not noticeable. More recently, we have found
that we are not getting away with it.
How do we deal with these risks? We do not know
for sure. We are now able to make qualitative estimates
that a hazard exists and possibly to make some broad
quantitative estimation. Then, in the absence of know-
ledge, we try to play it safe. As we get more knowledge,
we will narrow the safety margin. We will deal more
adequately in the future, but we have a long way to go.
QUESTION
What is the quantitative assessment of the risk
associated with involuntary exposure to carcinogens
compared with that of voluntary exposure to risk ele-
ments such as cigarettes, hallucinatory drugs, and so
forth?
RESPONSE: Dr. Jean French (NIOSH)
A chapter in the Surgeon General's Report deals
with the interaction between smoking and chemicals in
the workplace. However, that interaction has not been
appropriately addressed. Some of the smoking data have
not addressed occupational exposure. Even when looking
at an occupational setting, we often consider smokers
versus nonsmokers. There may be a much higher rate of a
particular adverse effect in smokers, most of which is
attributed to smoking. The conclusion is that smoking is
much more important than occupational exposure. How-
ever, with an appropriate control, where a group of
unexposed smokers and nonsmokers is compared with a
group of exposed smokers and nonsmokers, the effect
from occupational exposure often exceeds that from
heavy smoking, and the effect from exposure and
smoking may be tenfold. Often the difference between
occupational exposure and smoking is lost by the way
in which the data are presented. Occupational exposure
has really been undersold at the expense of cigarette
smoking because the data have not been appropriately
addressed.
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COMMENT
Living in society involves certain risks of exposure
about which we have no choice: effluents from power
plants, radiation from nuclear plants, radiation from the
sun. Occupational risks may be semivoluntary, in that one
must have a job and cannot always choose that job.
RESPONSE: Dr. Bates
Some studies have been made of how people accept
risks that are taken voluntarily—what level of risk is
acceptable voluntarily as opposed to the risk acceptable if
imposed.
COMMENT
Some decisions are made according to the degree of
our fear, not the degree of the risk. We have seen that
recently in connection with the worst air transportation
accident in history. That accident resulted in some very
drastic changes. Yet the deaths were equivalent to only
two days' worth of automobile traffic deaths. We are
very much afraid of airplanes, but we do not fear cars
that take many more lives.
RESPONSE: Dr. Albert
There may be a misconception involved when we
talk about reacting to things that we fear. In the case of
the Three-Mile Island accident, in which nobody was
killed, sensible people react to the fact that though there
has been a good deal of talk about how safe reactors are,
now it turns out they are not so safe. If the accident had
gone a little further and released large amounts of radio-
activity, large inhabited areas would have become unin-
habitable. The fear is related not so much to the killing
of people by functional nuclear reactors as to evidence
that reactors can break down so seriously that the risk of
a major escape of radioactivity is not farfetched.
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THE DEPARTMENT OF ENERGY'S DIESEL RESEARCH PROGRAM
Tom J. Alexander
Office of Environment
U.S. Department of Energy
Tom J Alexander
INTRODUCTION
The Department of Energy (DOE) has begun a 3- to 4-year research program to
assess the environmental acceptability of the light diesel engine. This program was
begun because of growing concern over the potential health hazard of diesel exhaust,
particularly the very fine particles, or particulates, emitted from the exhaust of diesel
engines. These particulates have been tested and shown to be mutagenic. The DOE
program is designed to help determine the extent of the diesel-exhaust health hazard
prior to use of diesel in large numbers of new cars and light trucks.
In order to meet increasingly stringent fuel economy standards through 1985,
some automakers introduced diesel engines into their new models beginning with
the 1977 model year. Prior to that time, diesels in passenger cars were rare, being
available only in relatively high priced cars such as the Mercedes Benz and the Peugeot.
With the advent of the General Motors and Volkswagon diesel engines, diesels may be
used in as many as 10% of the new cars and light trucks sold in the 1985 model year.
If all the environmental hurdles can be successfully passed, some researchers foresee
that as much as 40-50% of the market may ultimately be diesels. Since diesel engines
today have approximately a 25% fuel economy advantage over comparable gasoline
engines, the trend toward diesel may significantly reduce our nation's consumption of
petroleum in future years.
The diesel engine, while offering the advantages of fuel efficiency and reliability,
has several potentially severe drawbacks. It starts with difficulty in cold weather, lacks
the performance of an equivalently-sized gasoline engine, is noisy and odorous, and,
most important, may have excessively high levels of presently unregulated but possibly
carcinogenic (cancer-producing) exhaust pollutants. This last problem has caused the
greatest concern among government regulators and industry executives, since if these
pollutants are found to present an "unreasonable risk to human health,"* the diesel
engine could be effectively banned from use.
•Section 202(a)(4)(A) of the Clean Air Act as amended in 1977 (The Act).
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HEALTH CONCERNS
In November 1977, the Department of Energy was notified by the Environmental
Protection Agency (EPA) of the mutagenicity and potential carcinogenicity of
diesel exhaust emissions. Following a series of public meetings chaired by EPA to air
the issues and discuss the problems, as well as several meetings with EPA and Depart-
ment of Transportation (DOT) officials, DOE began planning in 1978 an extended
research program into the health effects and control technology of diesels. Its aim is
to supplement the research efforts at EPA and elsewhere as well as to offer DOE
management an assessment of the problem.
While the diesel may also have difficulty with control of oxides of nitrogen
(NOX), a regulated pollutant with possible deleterious health effects, the principal
concern of the DOE research is the potential hazard to human health posed by particu-
lates and associated heavy hydrocarbons, along with possible control measures. Com-
pared with gasoline spark-ignition engines, diesels produce a much greater amount of
particulates, from 30 to 100 times as much by weight. Table 1 shows the relative
emission levels from diesel engines and gasoline engines at 1981 model year emission
standards (assuming no particulate standards were in effect).
Particulates from diesels are very fine (90% are below 3.0 ^tgm in size) and have
very large surface areas. When inhaled, they penetrate deeply and remain in the lung
for a long time. In addition, adsorbed on and associated with diesel particulates are
significant amounts of heavy molecular-weight organic compounds. Certain fractions
of these organic compounds have been chemically analyzed and have been shown
to consist of polycyclic organic matter, including known animal carcinogens such as
benzo(a)pyrene [B(a)P] Mutagenic testing of diesel exhaust fractions (the Ames test)
has also shown positive results in some tests. Thus, there is a growing concern that
diesel exhaust emission may be proven to be carcinogenic. However, the evidence to
date is scanty and inconclusive; more definitive testing and research must be carried
out before the risk to human health from diesel exhaust can be finally determined.
TABLE 1
Relative emissions levels—1981 cars
HC
GM/MI
CO
GM/MI
NOX
GM/MI
Particulates
GM/MI
Benzo(a)Pyrene*
p. GM/MI
GASOLINE ENGINESt
— with catalyst
— without catalyst
DIESEL ENGINES
— uncontrolled
(GM data)
— controlled
research vehicle^
(Volkswagen)
0.41
3.4
1.0
0.23-0.7
0.17-0.45
0.90-1.8
1.0-2.5
1.2-1.8
0.4-0.5
0.007-0.011
0.24
0.29-0.92
0.25-0.48
1.5 with EGR
0.03-0.12
0.07 avg
0.29-5.3
2.7 avg
2.7
* R.L. Williams and SJ. Swarin, General Motors Research Labs, "Benzo(a)Pyrene Emissions from Gasoline and Diesel Automobiles," Society of
Automotive Engineers Paper #790419, presented at the Congress and Exposition, Detroit, Michigan, February 26-March 2, 1979.
t 1981 Federal emission standards for HC, CO, and NOX.
$ Data base for light-weight automotive diesel power plants, Volume I, September 1977, Report #DOT-TSC-IMHTSA-77-31.
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REGULATORY PERSPECTIVE
AND DOE ROLE
FUEL ECONOMY STANDARDS
OBJECTIVES
The light diesel engine faces several serious regulatory hurdles before it can be
fully utilized in the automotive market. On February 1, 1979, EPA proposed total
particulates exhaust standards that would require a phased reduction of exhaust emis-
sions from the present uncontrolled levels of 0.29-0.92 gram per mile (GPM), as
measured on the EPA's Federal Test Procedure (FTP), to 0.6 GPM for the 1981 model
year and 0.2 GPM for the 1983 model year. Particulate standards for model year
1981 were mandated by Congress in the 1977 Amendments to the Clean Air Act.
While difficult for larger engines to meet, the 1981 standard is generally thought to be
achieveable without after-treatment devices. The proposed, more stringent standards
for 1983 may require extensive development of after-treatment devices that are
presently in their early stages. The automobile manufacturers contend that these
devices cannot be available in 1983 and that the standard can't be met.
The diesel (and all autos) must also meet a stringent standard of 1.0 GPM for
NOx in 1981. This standard is particularly difficult for the diesel because the major
control technique needed for NOx exhaust gas recirculation (EGR) tends to increase
particulates while, on the other hand, control of particulates tends to increase NOX.
Clearly, meeting the 1.0 GPM NOx standard while trying to reduce particu-
lates will be a great technical challenge.
At present, no standard is being contemplated for controlling the organic mater-
ial associated with diesel particulates. However, under Section 206 of The Act, engine
manufacturers must prove that diesel emissions do not pose an "unreasonable risk
to human health" in order to obtain from EPA the certificate needed for their sale. If
they cannot do so to EPA's satisfaction, EPA could withhold issuance of a certificate
and effectively ban the diesel from the market.
The DOT has the authority and responsibility to set fuel economy standards. In
the past, because of the uncertainty about the potentially deleterious health effects of
diesel exhaust, DOT has not considered the use of diesel engines in its justification of
the fuel economy standards. However, if these uncertainties are resolved in favor of
the diesel, DOT may set standards in the future (post 1985) that would consider diesel
and, as a result, might be higher than would be the case without the consideration of
diesels. Therefore, possible future fuel economy gains may be forgone if diesels were
not included in the manufacturers' plans to meet the Corporate Average Fuel Economy
(CAFE) standards. The DOE's role in this regulatory arena is that of an advocate of
energy conservation using systems that are environmentally acceptable. DOE has no
direct regulatory authority over diesel engines as is the case with EPA. As an energy
conservation advocate, DOE wants to ensure that the diesel engine's environmental
acceptability can be proven; if it is found to be an "unreasonable risk to human
health," then we would probably support any necessary mitigative actions taken by
EPA.
The principal objective of the DOE diesel research program is to develop the in-
formation necessary to assess the environmental acceptability of the light-duty diesel
engines,* especially the potential toxicity or carcinogenicity of particulates emitted
by diesels. The research is directed toward an integrated risk assessment of light
diesels, including the relative risks of diesels vs. other light-duty engines or other health
risks. It will also assess the technical features of diesels, the potential control measures
that might be used for particulate reduction, and advanced diesel technologies.
The major objectives of the DOE diesel research program are to:
• Determine how diesel particulate production and toxicity are influenced by
engine parameters, emission control devices, fuel, and other factors.
• Resolve the uncertainty regarding carcinogenicity of diesel particulate emissions
under realistic exposure conditions.
*As defined by EPA-a diesel engine used in passenger cars under 6,000 pounds Gross Vehicle
Weight (GVWR) and light trucks (those under 8,500 pounds GVWR).
307
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SCOPE OF RESEARCH
• Develop quantitative predictive models for estimating human health risks under
specified conditions of exposure (air concentration and duration of exposure) to
diesel engine particulate emissions.
« Prepare an integrated assessment describing in quantitative terms the human
health risks and impacts that might be associated with large-scale deployment of
diesel engines in light-duty vehicles (LDVs).
• Provide interim assessments on an annual basis, including assessments that would
address implications of diesel particulate emission standards applicable to LDVs.
• Evaluate diesel vehicle emission control technologies, including engine modifica-
tions and after-treatment devices.
• Provide recommendations based on the completed integrated assessments, re-
garding the environmental acceptability of LDV diesel engines.
• Achieve better LDV diesel fuel economy with reduction of environmental impact
through combustion and advanced diesel research.
The diesel research program at DOE is directed toward the definition of the
potential deleterious health impacts of light-duty diesels, although its results might be
applied to heavy-duty and stationary diesels as well. Since industry projections are for
a significant increase in capital investment in diesel production capabilities in the earjy
1980's, interim results are planned for 1980 to contribute to an expected initial
determination of the potential risk to human health posed by light-duty diesels. Final
results of the research must be in by no later than 1983. The research plan calls
for three related and closely coordinated efforts within separate offices of DOE:
• Health Effects Research—Assistant Secretary for Environment (EV)
• Technology Assessment and Control Evaluation—Assistant Secretary for Con-
servation and Solar Applications (CS)
• Basic Engine Research and Development—Assistant Secretary for Energy Tech
nology (ET)
Health effects research will compose the major dollar portion of the diesel
research. This research will determine how diesel particulate formation and toxicity
are affected by engine parameters, control technology, fuel composition, and other
factors. Figure 1 shows the basic health-effect research strategy and its scope. Initial
diesel engine exhaust characterization data from both present uncontrolled engines and
EXPOSURE ASSESSMENT
DOSE
ASSESSMENT
INHALATION TOXICITY
ASSESSMENT
DIESEL EXHAUST
EMISSIONS
EXPOSURE
ATMOSPHERE
DEPOSITION
AND FATE
POPULATION
AT RISK
EFFECTIVE DOSE
TO SENSITIVE
TISSUES
HEALTH
EFFECTS
INTEGRATED HEALTH RISK ASSESSMENT
FIGURE -{-Inter-relationships in assessment of health effects from diesel exhaust
emissions
308
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EXPOSURE/DOSE
LEVEL LINKAGE
TECHNOLOGY
EVALUATION
BASIC ENGINE R&D
possible future controlled engines will be used to develop human exposure models.
Characterization will include not only the amount of particulates emitted, but data on
their detailed physical and chemical composition and their biological activity from
short-term tests. The exposure model will be developed from (a) emissions character-
istics data, (b) studies and models of particulate atmospheric transport, modification,
and fate, and (c) population-at-risk studies. The exposure model, coupled with dose
assessment studies, will contribute to the assessment of health effects.
Deposition and fate in animal and human systems of particulates and the asso-
ciated hydrocarbon material will be studied to calculate effective doses of toxic mater-
ials in sensitive tissues, particularly in the respiratory tract. In addition, the research
will investigate possible adverse health effects arising from the transport of these
materials from the lung to other parts of the body. This important dose assessment
task will not only link exposure levels to the dose levels in tissues, but also link animal
and human doses at comparable exposures. Lifetime animal inhalation studies of
chronically exposed mice and rats at multiple exposure levels will provide information
on the late-occurring health effects, since inhalation will be the primary mode of
human exposure to diesel exhaust. Information on life-span shortening, incidence and
nature of disease caused by the exposure, respiratory clearance function, and other
effects will be evaluated through the tests. From these and other studies, predictive
models for human health effects will be developed.
As a final product of the health-effects research, a risk assessment will be com-
pleted from information generated in the control technology evaluation as well as the
health research. Outputs from exposure, dose, and human-effects assessments will be
integrated to give an evaluation of the risk to human health posed by the light-duty
diesel. The health effects research will be conducted primarily at the Lovelace Inhala-
tion Toxicity Research Institute in Albuquerque, New Mexico, with the support of
DOE's Bartlesville Energy Technology Center in Bartlesville, Oklahoma.
The diesel technology assessment and control evaluation program is directed
toward the testing and evaluation of light-duty diesel engines and control technologies
to provide input into the health-effects research and to provide an assessment of
control feasibility. In addition, it will provide data on the effect of diesel engine
parameters and control concepts on particulate formation through single-cylinder
testing. Improved diesel engines now being developed for use in future models (includ-
ing turbocharged versions) will be evaluated for particulate formation and control
effectiveness. Samples will be provided to the Lovelace Institute for detailed character-
ization. Ongoing advanced diesel research and development will also be accelerated to
apply advances in ceramics, coatings, and heat recovery techniques being developed in
other DOE programs to increase the fuel economy of the diesel engine and decrease its
emissions. The technology tasks are being carried out at the National Aeronautics and
Space Administration's Lewis Research Center in Cleveland, Ohio, and at DOT's
Transportation Systems Center in Cambridge, Massachusetts.
A basic R&D program in combustion technology has been under way for over a
year under the direction of the Sandia Corporation at Livermore, California. Its aim is
to acquire basic combustion data using laser diagnostic techniques, its ultimate goal
being the design, development, and verification of detailed computer predictive models
to help guide future engine designs. The type of data to be developed includes infor-
mation on in-cylinder diagnostics, combustion and pollutant kinetics, fluid dynamic
modeling, and fuel spray formation, ignition, and combustion. The overall goal of the
research is a 20% improvement in the efficiency of the basic automotive internal
combustion engine. The combustion technology program is a joint effort with indus-
try, universities, and other research organizations. In addition to the diesel engine,
it is investigating the lean-burn and direct-injected stratified-charge engine. To focus
more on diesels, the program will be expanded to develop data on particulate forma-
tion and other diesel-related research.
The overriding need to determine whether or not diesels pose an unreasonable
risk to human health dictates that the assessment of the risk of increasing diesel usage,
and the balancing of that risk with the risk of not using the diesel, be of paramount
importance in the research program. The Act specifically did not limit to those factors
listed in Section 202(a)(4)(B) the criteria for determining whether an unreasonable risk
309
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RISK ASSESSMENT
exists. Since Congress was not specific in its intent with regard to other factors, the
criteria to be used must be developed along with the basic data.
A reasonable approach would seem to be that of a risk-balancing analysis, which
would assess not only the risks of diesels to human health, but the potential or actual
health risks faced by the population exposed to other pollutants and sources. How-
ever, a judgment of reasonableness comes not only from a numerical count of proba-
bility of incurring certain types of diseases or other hazards, but from a balancing of
the risks of continuing with the present course vs. the risks of not doing so. Thus, the
risks both to human health and to public welfare and safety must be considered. The
energy and economic consequences of a decision on diesels, while secondary to con-
siderations of risks to health, should also be taken into account in that determination.
The importance of the risk assessment and the test of reasonableness cannot be
stressed strongly enough. As more and more new or existing technologies and
products are found to pose possible health or safety problems, the means to judge
their potential hazard and relative importance is a critical need today. If we are to
make an informed and rational judgment, the data to assess risks must be available.
SUMMARY
The DOE's Diesel Research Program has as its ultimate goal the generation of
data and methodology to help determine whether or not the light-duty diesel engine
would "cause or contribute to an unreasonable risk to public health, welfare, or safety
in its operation or function." A comprehensive research program has been initiated to
(a) assess the health risks of diesels, chiefly from particulates and the heavy hydro-
carbons on them; (b) evaluate potentially available control technology, either already
in use or in development; (c) apply advanced diesel concepts for increased fuel effi-
ciency and reduced pollutant emissions; and (d) develop data and predictive models on
combustion and other engine phenomena through basic research. When completed in 3
to 4 years, the program should have contributed significantly to the technology infor-
mation base needed to determine the direction of public policy on this crucial issue.
310
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References
1. DOE Diesel Particulates Research Plan. Approved, January 1979.
2. Issues Concerning the Light-Duty Diesel, Draft. Office of the Assistant Secretary
for Environment, Department of Energy, June 1979.
3. J. F. Chalmers, et. al. Review of the Research Status on Diesel Emissions, Their
Health Effects, and Emission Control Technologies, Aerospace Report No. ATR-
78(7716)-3, Reissue A, prepared for the Division of Environmental Control Tech-
nology, Assistant Secretary for Environment, U.S. Department of Energy, June
1978.
4. W. U. Roessler, et. al. Diesel Engine Research and Development Status and
Needs, Aerospace Report No. ATR-78(7753)-1, prepared for the Division of
Transportation Energy Conservation, Assistant Secretary for Conservation and
Solar Applications, U.S. Department of Energy, September 1978.
'••'
• "\
*&+?-;. 17.., *<--.',•
311
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panel
discussion
313
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AUTOMOTIVE DIESEL PANEL DISCUSSION
Roger Cortesi, Ph.D.
Mobile Source Research Committee
Richard L. Strombotne, Ph.D.
National Highway Traffic Safety Administration
U.S. Department of Transportation
Tom J. Alexander
Office of the Assistant Secretary for Environment
U.S. Department of Energy
Charles Gray
Emissions Control Technology Division
U.S. Environmental Protection Agency
315
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DR. CORTESI: This is a discussion to introduce the sort of worry that goes on when a
major regulatory problem is coming up. The question has arisen as to whether we are
going to allow substantial dieselization of automobiles. In a simplified manner: basic
pros and cons resolve themselves to fuel saving versus a potential public health risk.
It is believed that a public health risk is being caused by fifty- to one hundred-
fold greater emissions of organic particles-per-mile from the diesel engine than from the
catalyst-equipped automobile. Absorbed onto these particles are tens of thousands of
organic compounds. Though it will be disputed, I can say that when all testing is done,
the diesel particles will exhibit carcinogenic activity because combustion products from
organic materials have always exhibited carcinogenic behavior and there is no reason to
suspect that there is something different about diesel soot. So the question is not
whether emissions are carcinogenic, but how carcinogenic are they? If we take a hard
line attitude on cancer, then basically we ban the diesel; if not, then we have to
balance off some risks and benefits.
EPA is concerned primarily that regulations properly consider the public health
interest. Probably more than any other division, EPA's Emissions Control Technology
Division is going to develop policies, decide whether to ban or regulate diesels, and
decide what sort of restrictions should be imposed. The Department of Transportation
(DOT) has the responsibility for getting out the regulations and timing them for the
Congressionally mandated miles-per-gallon that future cars will have to meet. The
Department of Energy (DOE) is the general tubthumper for increased energy conser-
vation and for keeping the Arabs from being too mean to us. All these interests are
not quite coincident.
Some of the pressure for the diesel car comes from General Motors. If they can
dieselize 25 percent of their fleet, they estimate that they can pick up one mile-per-
gallon on their fleet averages. To get this by other methods and still keep selling the
size cars that they would like to sell, they estimate that they would need an invest-
ment of $2 billion to $3 billion to lower the weight of the automobile by the use of
such substances as aluminum, plastic, and so forth. Chrysler's cash flow over the
next 5 years is estimated to be about $2.3 billion and General Motors' is estimated to
be about 10 times that. But this raises the question of not dieselizing to meet those
fleet averages because dieselizing may place very severe capital binds on some of the
less wealthy automobile manufacturing companies.
DR. STROMBOTNE:We at DOT do research relating to diesel engines and diesel engine
emissions, but I primarily want to emphasize our work on fuel economy. In December
1975, Congress passed the Energy Policy and Conservation Act, which set fuel
economy standards for passenger automobiles for model years 1978, 1979, and 1980
at 18, 19, and 20 miles-per-gallon and for model year 1985 at 27.5 miles per gallon.
Congress also requested DOT to set fuel economy standards at the maximum feasible
level for model years 1981 through 1984, considering technological feasibility,
economic practicability, the need of the nation to conserve energy, and the effect of
other Federal standards on fuel economy. On June 30, 1977, DOT set the standards
at 22, 24, 26, and 27 miles-per-gallon for model years 1981 through 1984,
respectively. When we analyzed the manufacturers' capability to improve fuel economy
for 1981 through 1984, we consciously set standards at levels that would not include
diesel engines. We did this because we were uncertain about their marketability and
their ability to meet the fairly tough oxides of nitrogen standards of 1 gram-per-mile
required in model year 1981. Also the question of possible unanticipated adverse
health effects of diesel engine emissions was raised and, therefore we will continue to
set fuel economy standards at levels that do not include diesel engines until we get
better information about health consequences. We have also set standards through
model year 1981 for what EPA terms light duty trucks and DOT calls light trucks.
This summer we plan to propose standards for model years 1982 through 1984 or
1985.
The diesel engine has a fuel economy advantage of approximately 25 percent
over the spark ignition engine when the comparison is made on an equal power basis.
Diesel engines are therefore interesting for reasons of both energy conservation and
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fuel economy. From our present research, it is possible that even further improvements
may be available. For example, turbo-charged diesel engines may exhibit a 10- to
15-percent improvement over nonturbo-charged diesel engines. Mercedes Benz now
makes a turbo-charged diesel engine. Two years ago, under a research contract,
Volkswagen delivered to DOT an experimental turbo-charged diesel Rabbit that had 50
to 55 or 60 miles-per-gallon on the EPA driving cycle and a 2,250-pound inertia
weight. That is a very respectable fuel economy.
Another possible technology for automobile application is direct injection instead
of a prechamber type engine. Again, it may be possible to get a 10- to 15-percent
improvement in fuel for passenger car engines but that is, however, strictly in the
research phase. Before 1985 we do not expect to see fuel economy savings that are
due to the use of diesel engines because we expect the average fuel economy standards
will be met but probably not exceeded by very much. Since the standards apply to a
manufacturer's average production, not to individual vehicles, the manufacturer has a
wide range of options as to what choices and what technologies or approaches he uses
to meet the standards. He can reduce weight, change the mix of car sizes, reduce
aerodynamic drag, increase efficiency of engines, improve his transmissions, or bring in
alternative engines such as the diesel. There are many options, and different companies
are using different approaches. To clarify the statement that there will not be fuel
savings, diesel engines seem to exhibit better performance on the road when a
comparison is made between them and the spark ignition engines at the same EPA fuel
economy rating, and they also get better fuel economy. There is some discrepancy in
preliminary data from DOE. Their surveys indicate that the discrepancy for the diesel
engine is about half as great as it is for the spark ignition engine. To the extent,
therefore, that diesel engines are used rather than spark ignition engines, there would
be some fuel savings.
For our part, we are looking at what could be done in the future to improve
fuel economy. We would expect to bring diesel engines into our thinking in setting
fuel economy standards that would apply at the earliest after 1985. As we assess the
manufacturers' future capability to improve fuel economy and we have better informa-
tion about the health effects of diesel engines, it may be appropriate to include diesels
among the things that manufacturers will be able to use. We made estimates as to what
fuel savings we could get with a 25-percent usage rate for diesel engines, and we
estimated an increase at a linear rate from 1980 to 1985, winding up at 25 percent in
1985, and then holding steady. The fuel savings would then be about 300,000 barrels
per day in the early 1990's, with total savings to the year 2000 at about 1J/2 billion
barrels.
In 1978, automotive diesel engines accounted for 0.8 percent of the market. The
market, now at 2.4 percent is growing quite rapidly, but is supply-limited. The manu-
facturers are able to sell all their engines and they have a long waiting list of
customers. In this country, they are currently being marketed by General Motors,
Volkswagen, Mercedes Benz, and Peugeot. General Motors' sales already exceed more
than half of the total diesel market. Mercedes Benz relies very heavily on diesel engine
sales. In this country, over 75 percent of their sales are diesel engines. General Motors,
at the moment, has made the largest commitment to diesel engines and has two sizes,
a 350-cubic-inch engine and a 260-cubic-inch engine. They.are planning to introduce
other sizes in the future. They expect that by 1983 the diesel engine will account for
about 13 percent of their sales and by 1985 perhaps 16 percent.
There are some uncertainties in the market. It is known that buyers of diesel
engines are not typical of all car buyers. There is the question of what effect the
growing difficulties in getting good quality diesel fuel will have on buyers. There is still
some question about the general acceptability of diesels because of the problems with
odor, noise, high cost, and cold temperature starting. We have projected that diesels
may account for about 9 percent of the total market by 1985, but that is based
strictly on manufacturers' plans and not on market surveys.
MR. ALEXANDER: The diesel has become a matter of great public debate and
DOE was pulled into it because of its role as an advocate of energy conservation.
In the Diesel Research Program we expect to supplement the work being done
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by EPA and, at the same time for DOE management, to assess the diesel for
both short-term and long-term policy determinations. EPA is the primary regula-
tory body. We along with other parts of government will be involved in a
policymaking decision, but for policy determination as far as emissions are
concerned, the responsibility ultimately lies with EPA. DOT is responsible for
fuel economy under sections 202 and 206 of the act.
Our role is not as a diesel advocate, but as an energy conservation advocate. To
the extent that diesels can show an incremental reduction in fuel consumption and can
be shown to be environmentally acceptable, we would support the diesel. I think that
is a very large caveat. Since I represent the Office of the Environment, our principal
concern is the environmental acceptability of the diesel. But if the hurdle of the EPA
regulations can be jumped, we should presumably support the diesel and its use in
meeting the fuel economy standards.
In the DOE Diesel Research Program, we are principally responsible for
determining the potential carcinogenicity or health hazard, in particular, of the
particulates emitted by the diesel. The end product of our program will be an
integrated risk assessment that we hope we will have for policy determination within
3 or 4 years of this program. We recognize that decisions have to be made in the
short term and consequently hope to have interim results by the early 1980's.
From our DOE program plan describing our research I would like to read some
of our objectives and show how they relate to both EPA's program and this policy
determination. In the order of accomplishment, these objectives are:
• To determine how diesel particulate production and toxicity are influenced by
engine emission control devices, fuel, and other factors.
• To resolve the uncertainty regarding the carcinogenicity of diesel particulate
emissions under realistic exposure conditions.
• To develop quantitative predictive models for estimating human health risks
under specified conditions of exposure and diesel emissions.
• To prepare an integrated assessment describing in quantitative terms human
health risks and impacts that might be associated with a large-scale deployment
of diesel engines in light duty vehicles.
• To make recommendations, based on the completed integrated assessments,
regarding the environmental acceptability of light duty diesel engines.
The research has been initiated and is being carried out under three separate
offices of DOE:
• Health effects research is primarily under our Office of the Environment.
• Control technology evaluations and sample generations are done by the Office of
Conservation and Solar Application.
• Basic research on combustion phenomena, which have been going on for a year
and which are expected to continue for the next several years, are under the
Energy Technology Group.
Our health effects program starts by characterizing existing and potential engines,
such as the turbo-charged version or advanced engines being developed today by the
automakers for use in the 1983-1984 period. From there we would define the
exposure atmosphere and the atmospheric transformation and transport phenomena
that diesel particulates might be exposed to, as well as the population-at-risk model.
We would couple that, for dose assessment purposes, with a deposition and fate study
of the particulates and their associated hydrocarbons in the body. We would then look
at effective doses to sensitive tissues, either in the lung through inhalation studies or
in other parts of the body where there is transport of the materials. We would finally
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integrate all of these to determine the health effects and to make an integrated health
risk assessment. Our program involves (1) short-term bioassays and chemical characteri-
zation of the particulates and hydrocarbons and (2) long-term multiple-exposure animal
studies to look at the late-occurring chronic effects of diesels. Because of late-occurring
effects, the animal studies would be carried out over the next 3 years and therefore we
would not have the results from the interim sacrifices of animals and other types of
tests to enable us to help develop a DOE position on diesels over the next 2 years.
To reiterate, DOE is concerned that the diesel be environmentally acceptable and
that the environmental acceptability be proven under the case set forth in the act. The
act says specifically that no device—presumably the diesel would fall under this—shall
pose an unreasonable risk to public health, welfare, or safety and that, among other
factors, the control technology, technical feasibility, and so on must be considered.
The roles of both quantitative and qualitative assessments of the risk are very
critical items. We cannot assess by a strict quantitative estimate of what the probability
of cancer would be from various devices or tests under certain conditions; there has to
be a risk balancing approach. Basically the assessment is the risk of continuing with
the increased use of diesel engines for most of the light duty fleet versus the risk of
not using diesels in the automotive fleet. This assessment of comparative risks is very
critical. The diesel can potentially offer a rather significant effect on our fuel conserva-
tion goals over the next decade or two. If not available, we would presumably lose
those 300,000 barrels and have to make them up from some other source.
In summary, the role of DOE is not only as an energy conservation advocate, but
also for both our purposes and EPA's, to make sure that the diesel engine is environ-
mentally acceptable before its large-scale use. On either hand, we want to ensure that
the case for or against the diesel be reasonably made.
MR. GRAY: EPA is concerned about the environmental implications of the diesel,
especially considering its projected widespread use in the automobile market. Perhaps
25 percent of passenger car production could be diesel-powered by as early as 1985.
We are, of course, aware that in the same weight car the diesel engine offers a fuel
economy improvement over the gasoline engine. Just to clarify this point, even General
Motors has testified that the diesel would not be used to reduce fuel consumption in
this country, but would only be used as a more inexpensive way to meet the corporate
average fuel economy standards. It would take a policy decision by DOT to set more
stringent fuel economy standards to take advantage of the diesel engine. So, in and of
itself, the position of the industry is that the diesel will not be used to reduce fuel
consumption.
Diesels have other advantages besides fuel economy potential, even in the
emissions area. They tend to have inherently low regulated emissions, although not as
low as those of gasoline engines equipped with catalytic control systems. But the diesel
engine is not as sensitive to in-use deterioration of emission performance.
Mass particulate emissions from diesels are significantly higher than those from
gasoline engines. For example, diesels today emit from 0.2 to 0.1 gram-per-mile
particulates while a catalyst-equipped gasoline vehicle will emit somewhat less than
0.03 grams-per-mile. The composition of particulates differs also. Particulates from
catalyst-equipped gasoline vehicles consist mostly of sulfates or sulfuric acid, with small
quantities of high molecular weight hydrocarbons. Early this year in response to the
Clean Air Act amendments, EPA reported to Congress that the quantity of sulfates
emitted from catalyst-equipped gasoline vehicles is not expected to be an environ-
mental problem. On the other hand, diesel particulate emissions consist of chains of
carbonaceous spheres with associated organics that are at least mutagenic and possibly
carcinogenic.
Two regulatory activities currently under way in EPA address the light duty
diesel, and a number of research programs address the carcinogenic concerns. First,
last February EPA proposed light duty diesel total particulate mass standards of 0.6
gram-per-mile and 0.2 gram-per-mile effective for 1981 and 1983. Section 202 of our
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Clean Air Act requires EPA to set standards no later than the 1981 model year. These
standards represent what EPA feels is the greatest degree of emission control feasible
within that same time frame and will help to ensure that the ambient air quality
standard for total suspended particulates is attained and maintained. Diesel particulates
are composed of such small particles that they penetrate the innermost portions of the
lung. As compared with other particles that make up the total urban suspended
particulates, there are more than 1,000 times unit particles per unit mass. For example,
it would take 5,000 micrograms of coal-fired power plant particulates to contain the
same number of particles as one microgram of diesel particulates. EPA is especially
concerned about this and recently held public hearings and received a number of
comments. The proposed standards are being finalized at this time.
There is a possibility of relaxing the current NOX standard by 50 percent and
extending it up to 1985. The waiver request submitted by General Motors, Volks-
wagen, and Mercedes Benz demonstrates this necessity and EPA must decide that
to grant the waiver is in the best interest of the country. EPA is also doing major
research to determine whether diesel paniculate emissions result in an unreasonable
carcinogenic risk. There is a wide range of efforts under way. We are focusing on an
initial risk assessment in the very near term, followed by perhaps two additional risk
assessments as more information is obtained. We feel the urgency of this potential
problem because beginning this fall, General Motors, in particular, is for the next 2
to 3 years planning to make a massive investment in diesels. It is critical for the
Federal government to take a position at this time so that such massive investments
will not be wasted if studies indicate that the diesel is a risk and its production should
be limited. Over the last year EPA has clearly expressed the position that before the
manufacturers commit themselves to the diesel engine, they should provide assurance
that their new engines do not pose a serious cancer threat. The burden of proof of
their safety belongs with the manufacturers who will profit from their use.
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questions
& answers
Mr. David Jopling
Florida Power and Light Company, Miami
Mr. Mike Russin
American Petroleum Institute
Mr. William Martin
Integrated Energy Systems, Chapel Hill, NC
QUESTION
Are any panel members aware of tests or plans for
tests of coal-based liquids for automotive fuels,
particularly diesel?
RESPONSE: Mr. Tom Alexander (DOE)
I know of no plans for automotive fuels. Under our
alternative fuels program we are looking at a program of
stationary applications for large marine diesels which have
very low speeds compared with high-speed automotive
engines.
COMMENT
The Electric Power Research Institute speculated
about whether SRC-2 can function as a diesel fuel. A lot
of unwanted things in traditional diesel fuel can be
removed from SRC-2 because it is highly refined. If plants
are constructed to produce coal-based liquid to compete
head-to-head as boiler fuel and if there is a market for it
as automotive fuel, the competition for available produc-
tion might be very stiff.
RESPONSE: Mr. Alexander
The Department of Energy is now starting an
assessment of synthetic fuel development and also has
under way an alternative fuels group within the Office of
Conservation and Solar Application. Ultimately each one
of the synthetic and the natural fuels will have a place
that is most advantageous. For example, oil shale is better
than natural petroleum for diesel fuels because it seems to
have a larger cut of middle distillates. Synthetic fuels can
also be blended with other fuels in a regular refinery
process to produce the desired product. I think all of
those are being assessed individually and collectively.
Better information should be available within the next
year or two.
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RESPONSE: Mr. Charles Gray (EPA)
EPA definitely has plans to test the emissions from
diesel engines burning coal-based fuel. If there are any
ready sources of the fuel, we would be glad to begin a test
program right away.
QUESTION
There are, I understand, substantial differences not
just in emissions from diesel versus gasoline engines, but
in the distribution and manufacture of those fuels that
have varying environmental effects. For example, being
much more volatile, gasoline tends toward high-lead con-
centrations, unless expensive controls are put into higher
evaporative losses. Likewise, gasoline generally takes
considerably more energy to produce. Do any of the
panelists have any comments on this or on whether these
effects are being quantitatively determined?
RESPONSE: Mr. Gray
The effect of the different costs of processing has
been taken into consideration in establishing the way of
expressing the diesel fuel economy figure, the miles per
gallon equivalent. It includes not only the different energy
content of a gallon of diesel fuel, but also the difference in
energy consumption necessary to produce that gallon of
diesel fuel. To that extent, it has already been taken into
consideration.
RESPONSE: Mr. Alexander
DOE has assessed, in fact, four studies done by the
petroleum refining industry. I believe they were Amoco,
Mobil, Exxon, and one other. Each one of these has a
different result, on both price and energy effect. The auto
industry, I understand, has canvassed the petroleum
refining industry for the price effect of the diesel under
increasing scenarios of its use. The results are that price
parity of diesel fuel with gasoline will probably be
reached if diesel fuel production becomes greater than
about 40 percent of the total automotive fuel production.
We might then see an increase in the price both of diesel
fuel relative to gasoline and of energy intensity.
QUESTION
/ am conducting a study for the Swiss government
and I estimate that reaching a level of 40-percent to
50-percent dieselization of the fleet of passenger cars in a
European city would drive the population out simply
because of the problems of soot, deposit, visibility, et
cetera. Perhaps it can be called an aesthetic problem. I am
aware that European cities may be built differently than
American cities, but we know from complaints that by
having just that number of diesel buses and diesel trucks
on the roads we are going to have a serious odor problem.
What has been done in terms of the nuisance problem
associated with emissions from diesel engines?
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RESPONSE: Dr. Roger Cortesi (EPA)
If we do not take a ban-the-diesel approach, control
technology fixes are implied. It is possible that these fixes
will indeed reduce the odor the same way a catalyst
would knock out odors. Some of the fixes actually have
catalysts in the forward part. I cannot speak for how the
agency will regulate the soot or what the timetable will be,
but I will be very surprised if we do not end up with an
even tighter number than that mentioned by Mr. Gray. We
feel that would help alleviate the soot problem.
RESPONSE: Mr. Gray
The particular standards that have been proposed
should be sufficient to reduce at least the visibility prob-
lem with the diesel vehicle. There is hope that the strict
hydrocarbon control standards in this country will reduce
the amount of odor emitted from a diesel vehicle. All we
plan to do at this stage is to monitor that aspect to see if
it does develop into a problem.
QUESTION
Because of the mutagenic and possibly carcinogenic
effects, humans cannot be exposed to diluted diesel
exhaust. Has 'there been any chemical analysis of the
diesel exhaust and has that proceeded far enough for
determining what tends to be predominant particles or
respirable particluates or gases? One possible combination
would be a carbon and possibly NO2 as a gas. Where does
that type of study stand with respect to those pollutants
that humans could be exposed to for determining a model
effect of diesel exhaust?
RESPONSE: Dr. Cortesi
At levels we are concerned about, carcinogenicity is
the low level threat. Skipping the carcinogenic effect, we
are concerned about the possible respirable effects of
particles themselves. We believe we are coping with those
problems via studies about the effects of carbonaceous
particles on the human for other regulatory programs
such as the ambient air standards. To see what the effects
are, we also do chronic animal studies and acute clinical
studies on human beings. That aspect of it is being coped
with in other programs. The carcinogenic endpoint is our
current concern.
323
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participants' index
Abbott, James . Page 103
EPA/IERL
Research Triangle Park, NC 27711
919/541-2925
Albert, Ph.D., Roy . Page 295
EPA/Carcinogen Assessment
Group
401 M Street, SW
Washington, DC 20460
202/755-3968
Alexander, Tom . Page 305, 315
DOE
20 Massachusetts Ave., NW
Washington, DC 20545
202/376-9073
Anderson, Ph.D., Elizabeth. Page 295
EPA/Carcinogen Assessment
Group
401 M Street, SW
Washington, DC 20460
202/755-3968
Barber, Walter . . Page 29
EPA/OAQPS
Research Triangle Park, NC 27711
919/541-5315
Bates, Ph.D., Richard. . Page 295
HEW/NIEHS
Bethesda, MD 20205
301/496-3511
Baucus, The Honorable Max . Page 7
United States Senate
Washington, DC 20510
Bowen, D. Eng., Joshua. . Page 69
EPA/IERL
Research Triangle Park, NC 27711
919-541-2470
Clusen, Ruth Page 23
Assistant Secretary for
Environment
DOE
20 Massachusetts Ave., NW
Washington, DC 20545
202/376-4185
Comar, Ph.D., Cyril. Page 295
Electric Power Research Institute
Palo Alto, CA 94303
Cortesi, Ph.D., Roger. . . Page 315
E PA/OH EE
401 M Street, SW
Washington, DC 20460
202/755-9210
Davis, Swep. . . . Page 33
EPA/OWPS
401 M Street, SW
Washington, DC 20460
202/755-0402
Drehmel, Ph.D., Dennis . . Page 103
EPA/IERL
Research Triangle Park, NC 27711
919/541-2925
Eisenhower, William . . . Page 251
Oak Ridge National Laboratory
Oak Ridge, TN 37830
615/574-0684
Elder, H.William Page 147
TVA/Emission Control
Development Projects
Muscle Shoals, AL 35660
205/383-4631
Freedman, Ph.D., Steven . Page 135
DDE/Division of Fossil
Fuel Utilization
Washington, DC 20545
301/353-2800
French, Ph.D., Jean. . . . Page 295
HEW/NIOSH
5600 Fishers Lane
Rockville, MD 20857
301/443-6377
Gardner, Ph.D., Donald . . Page 261
EPA/HERL
Research Triangle Park, NC 27711
919/541-2531
Gipson, Larry . . Page 251
P.O. Box Y
Oak Ridge National Laboratory
Oak Ridge, TN 37830
615/574-0684
Glass, Ph.D., Gary. . .Page 223
EPA/ERL
6201 Congdon Blvd.
Duluth, MN 55804
218/727-6692
327
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Glass, Ph.D., Norman
EPA/Terrestrial Systems
Division
200 SW 35th Street
Corvallis, OR 97330
503/757-4671
Graham, Judith
EPA/HER L
Research Triangle Park, NC 27711
919/541-2531
Page 223
Gray, Charles .
EPA/Emission Control
Technology Division
2565 Plymouth Road
Ann Arbor, Ml 48105
313/668-4204
Harmon, D. L. . .
EPA/IERL
Research Triangle Park, NC 27711
919/541-2925
Harvey, William . . . . .
DDE/Division of Fossil
Fuel Utilization
Washington, DC 20545
301/353-2810
Hess, Ph.D., Wilmot.
NOAA/ERL
325 Broadway
Boulder, CO 80303
303/499-1000
Page 261
Page 315
Page 103
Page 135
Page 162
Holland, D.V.M, Ph.D., Michael. .
Oak Ridge National Laboratory
Oak Ridge, TN 37830
615/574-0678
Jones, Julian
EPA/IERL
Research Triangle Park, NC 27711
919/541-2489
Kerr, Ph.D., Donald
DOE/Energy Technology
Washington, DC 20585
202/252-6850
Lyons, Ph.D., Walter
Mesomet, Inc.
190 North State Street
Chicago, IL 60601
312/263-5921
Martin, George Blair . . .
EPA/IERL
Research Triangle Park, NC 27711
919/541-2235
Page 251
Page 117
Page 11
Page 189
Page 69
Maxwell, Michael Page 49
EPA/IERL
Research Triangle Park, NC 27711
919/541-2578
McKinney, Ph.D., B. G
Electric Power Research Institute
516 Franklin Building
Chattanooga, TN 37411
615/899-0072
Page 147
Menzel, Ph.D., Daniel
P.O. Box 3813 Medical Center
Duke University
Durham, NC 27710
919/684-3915
Mills, Ph.D., Michael
Teknekron Research, Inc.
2118 Milvia Street
Berkeley, CA 94704
617/890-6270
Plehn, Steffen.
EPA/OSW
401 M Street, SW
Washington, DC 20460
202/755-9170
Princiotta, Frank.
EPA/I EPD
401 M Street, SW
Washington, DC 20460
202/755-2737
Page 261
Page 233
Page 37, 41
Page 147
Rennie, Ph.D., Peter
Canadian Forestry Service
Environment Canada
Ottawa, Ontario, Canada KLA-OH7
819/997-3004
Reznek, Ph.D., Steven ....
EPA/OEET
401 M Street, SW
Washington, DC 20460
202/755-4858
Richards, Ph.D., Norman .
EPA/ERL
Sabine Island
Gulf Breeze, FL 32561
904/932-5311
Page 223
Page 3
Page 171
Shapiro, Michael . . . .
DOE/Division of Fossil
Fuel Utilization
Washington, DC 20545
301/353-2843
Page 49, 147
328
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Smith, Lawton ..............
P.O. Box Y
Oak Ridge National Laboratory
Oak Ridge, TN 37830
615/574-1276
Smith, Ph.D., Lowell ..........
EPA/OEET
401 M Street, SW
Washington, DC 20460
202/755-2737
Sparks, Ph.D., Leslie ..........
EPA/IERL
Research Triangle Park, NC 2771 1
919/541-2925
Stephens, Thomas ............
P.O. Box Y
Oak Ridge National Laboratory
Oak Ridge, TN 37830
615/574-0684
Strombotne, Ph.D., Richard .....
DOT/NHTSA
400 7th Street, SW
Washington, DC 20590
202/426-0846
Whitaker, Mary ..............
P.O. Box Y
Oak Ridge National Laboratory
Oak Ridge, TN 37830
615/574-0684
Wilson, Ph.D., William .........
EPA/ESRL
Research Triangle Park, NC 27711
919/541-2551
Page 251
Page 233
Page 103
Page 251
Page 315
Page 251
Page 211
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federal agency acronyms
DOE Department of Energy
EPA Environmental Protection Agency
EMSL Environmental Monitoring and Support Laboratory
ERL Environmental Research Laboratory
ESRL Environmental Science Research Laboratory
HERL Health Effects Research Laboratory
I ERL Industrial Environmental Research Laboratory
OEET Office of Environmental Engineering and Technology
HEW Department of Health, Education and Welfare
NIEHS National Institute of Environmental Health Sciences
NIOSH National Institute of Occupational Safety and Health
HUD Department of Housing and Urban Development
NASA National Aeronautics and Space Administration
TVA Tennessee Valley Authority
USDA U.S. Department of Agriculture
ESCS Economics, Statistics and Cooperative Service
FS Forest Service
SCS Soil Conservation Service
SEA/CR Science and Education Administration, Cooperative Research
SEA/FR Science and Education Administration, Federal Research
USDC U.S. Department of Commerce
NBS National Bureau of Standards
NOAA National Oceanic and Atmospheric Administration
OEA Office of Environmental Affairs
USDI U.S. Department of Interior
BOM Bureau of Mines
FWS Fish and Wildlife Service
USGS U.S. Geological Survey
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