National Academies Press: OpenBook
Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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COMMITTEE PRINT

AIR QUALITY AND STATIONARY SOURCE EMISSION CONTROL

A REPORT BY THE

COMMISSION ON NATURAL RESOURCES

NATIONAL ACADEMY OF SCIENCES

NATIONAL ACADEMY OF ENGINEERING

NATIONAL RESEARCH COUNCIL

PREPARED FOB THE

COMMITTEE ON PUBLIC WORKS

UNITED STATES SENATE

PURSUANT TO

S. Res. 135

APPROVED AUGUST 2, 1973

MARCH 1975

SERIAL NO. 94–4

Printed for the use of the Committee on Public Works

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1975

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington, D.C. 20402—Price $8.60

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
×

COMMITTEE ON PUBLIC WORKS

JENNINGS RANDOLPH,

West Virginia,

Chairman

EDMUND S.MUSKIE,

Maine

JOSEPH M.MONTOYA,

New Mexico

MIKE GRAVEL,

Alaska

LLOYD BENTSEN,

Texas

QUENTIN N.BURDICK,

North Dakota

JOHN C.CULVER,

Iowa

ROBERT MORGAN,

North Carolina

GARY W.HART,

Colorado

HOWARD H.BAKER, JR.,

Tennessee

JAMES L.BUCKLEY,

New York

ROBERT T.STAFFORD,

Vermont

JAMES A.MCCLURE,

Idaho

PETE V.DOMENICI,

New Mexico

M.BARRY MEYER, Chief Counsel and Chief Clerk

BAILEY GUARD, Minority Clerk;

RICHARD A.HELLMAN, Minority Counsel

LEON G.BILLINGS, Senior Staff Member

PHILIP T.CUMMINGS, Assistant Chief Counsel;

JOHN W.YAGO, Jr., Assistant Chief Clerk

RICHARD M.HARRIS,

MARGARET L.WORKMAN,

JAMES W.CASE, and

RICHARD E.HEROD (minority), Assistant Counsels

RICHARD E.KAIT (minority), Legal Assistant

Professional and Research Staff: KARL R.BRAITHWAITE,

HAROLD H.BRAYMAN,

EDWARD O.CALLAN,

PAUL CHIMES,

TRENTON CROW,

KATHERINE Y.CUDLIPP,

JOHN D.KWAPISZ,

PAUL F.EBELTOFT, Jr.,

GEORGE F.FENTON, Jr.,

RANDOLPH G.FLOOD,

KATHALEEN R.E.FORCUM,

ANN GARRABRANT,

RICHARD T.GREER,

RICHARD D.GRUNDY,

WESLEY F.HAYDEN,

VERONICA A.HOLLAND,

RONALD L.KATZ,

LARRY D.MEYERS,

JUDY F.PARENTE,

JOHN B.PURINTON,

MARGARET E.SHANNON,

CHARLENE A.STURBITTS,

E.STEVENS SWAIN, Jr., and

SALLY W.WALKER

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
×

NOTICE

The project that is the subject of this report was approved by the Governing Board of the National Research Council, acting in behalf of the National Academy of Sciences. Such approval reflects the Board’s judgment that the project is of national importance and appropriate with respect to both the purposes and resources of the National Research Council.

The members of the groups selected to undertake this project and prepare this Report were chosen for their individual scholarly competence and judgment with due consideration for the balance and breadth of disciplines appropriate to the project. Responsibility for all aspects of this report rests with those groups, to whom sincere appreciation is hereby expressed.

Although the reports of our study committees are not submitted for approval to the Academies’ membership or to the Board, each report is reviewed by a second group of scientists according to procedures established and monitored by the Academies’ Report Review Committee. Such reviews are intended to determine, among other things, whether the major questions and relevant points of view have been addressed and whether the reported findings, conclusions, and recommendations arose from the available data and information. Distribution of the report is approved by the President only after satisfactory completion of this review process.

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
×

COMMISSION ON NATURAL RESOURCES

Gordon J.F.MacDonald, Chairman,

Dartmouth College

William C.Ackerman,

Illinois State Water Survey

Thomas D.Barrow,

Exxon Corporation

John E.Cantlon,

Michigan State University

Harold L.James,

U.S. Geological Survey

Allen V.Kneese,

University of New Mexico

John J.McKetta,

The University of Texas at Austin

Emil M.Mrak,

University of California, Davis

William K.Reilly,

The Conservation Foundation

Robert M.Solow,

Massachusetts Institute of Technology

Gilbert F.White,

University of Colorado

E.Bright Wilson,

Harvard University

Ex officio (Chairmen of Boards)

Norman Hackerman,

Rice University

Howard W.Johnson,

Massachusetts Institute of Technology

Robert W.Morse,

Woods Hole Oceanographic Institution

Elbert F.Osborn,

Carnegie Institution of Washington

Sylvan H.Wittwer,

Michigan State University

Richard A.Carpenter, Executive Director

Raphael G.Kasper, Staff Officer

Robert C.Rooney, Editor

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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NATIONAL ACADEMY OF SCIENCES

OFFICE OF THE PRESIDENT

2101 CONSTITUTION AVENUE WASHINGTON D.C. 20418

March 3, 1975

The Honorable Jennings Randolph

Chairman

Committee on Public Works

United States Senate Washington, D.C. 20510

Dear Mr. Chairman:

I have the honor to transmit the report entitled “Air Quality and Stationary Source Emission Control” which was prepared for the Committee on Public Works of the U.S. Senate, pursuant to the request in your letter of 18 September 1974.

This study was organized by the Commission on Natural Resources in cooperation with other major units of our National Research Council. As noted in the Introduction, individual chapters were first prepared by specific individuals or groups. Each chapter was carefully reviewed by the parent unit, e.g., the Assembly of Life Sciences or the Assembly of Engineering and by the Commission; the latter’s review guided preparation of the final chapter drafts, particularly the chapter entitled “Part Two in Brief, Strategies for Controlling Sulfur-Related Power Plant Emission.” From the report proper, the Commission prepared the Introduction and Summary; each statement also carries the approval of the cognizant unit. In addition, the report was reviewed by an independent panel appointed by our standing Report Review Committee and the report is now compatible with the recommendations of these reviewers.

The report deals with yet another instance of great concern for protection of the environment and of the public health in which the body of available, reliable, pertinent information is less clear in compelling conclusion than national decision-makers may reasonably require. Perhaps

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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the principal contribution of the report is to reveal what is and is not known and, in this way, guide both the decisions which must be taken in the face of uncertainty and the future research program necessary to reduce that uncer tainty.

Sincerely yours,

Philip Handler

President

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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PART TWO:
STRATEGIES FOR CONTROLLING SULFUR-RELATED POWER PLANT EMISSIONS

 

 

 

 

Part Two in Brief: Strategies for Controlling Sulfur-Related Power Plant Emissions

 

193

   

 Relation of Emissions to Ambient Air Quality and Chemistry of Precipitation

 

193

   

 Efficient Pricing and Conservation

 

197

   

 Modification of Demand for Electric Power

 

199

   

 Flue Gas Desulfurization (FGD)

 

202

   

 Control of Ambient Sulfur Dioxide Concentrations with Tall Stacks and/or Intermittent Control Systems

 

212

   

 Other Techniques for Reduction of Sulfur in the Atmosphere

 

217

   

 Analysis of Alternative Strategies

 

220

 

 

Section 1: Relationship of Emissions to Ambient Air Quality and Chemistry of Precipitation

 

232

Chapter 6:

 

The Relationship of Sulfur Oixde Emissions to Sulfur Dioxide and Sulfate Air Quality

 

233

   

 Sulfur Oixde Emissions

 

235

   

 Sulfur Dioxide Air Quality

 

240

   

 Sulfate Air Quality

 

245

   

 Ambient Air Quality Trends for Sulfur Dioxide and Sulfate

 

254

   

 The Air Quality Impact of Projected Increases in Power Plant Emissions

 

264

   

 Literature Cited

 

271

Chapter 7:

 

Sulfates and Acidity in Precipitation: Their Relationship to Emissions and Regional Transport of Sulfur Oxides

 

276

   

 Introduction

 

276

   

 The Sulfur Cycle and Sulfate Deposition

 

277

   

 Sulfates in Precipitation in Eastern North America

 

279

   

 Acidity of Precipitation in Eastern North America

 

284

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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 The Relationship of Acid Precipitation to Emissions of Sulfur and Nitrogen Oxides

 

290

   

 Evidence for Long Range Transport and Deposition of Sulfur Oxides

 

293

   

 Summary of Comparable Observations in Europe

 

294

   

 Projected Consequences of Increased Emissions in 1980

 

296

   

 Neutralization and Run-off to Acidified Precipitation

 

300

   

 Summary and Conclusions

 

302

   

 Footnotes

 

303

   

 Literature Cited

 

308

 

 

Section 2: Techniques for Reducing Emissions from Power Plants

 

313

Chapter 8:

 

Pricing Policy and Demand for Electricity

 

314

   

 Efficient Pricing and Conservation

 

314

   

 Demand Projections and Elasticity

 

318

Chapter 9:

 

Effects of Improved Fuel Utilization on Demand for Fuels for Electricity

 

323

   

 Introduction

 

323

   

 Patterns of Fuel Supply and Demand

 

324

   

 Potential for Improved Effectiveness

 

332

   

 Potential for Shifting to Alternate Sources for Space Heating

 

341

   

 Evaluation of Capital Cost Factors

 

343

   

 Summary of Demand Modification Alternatives

 

348

   

 Effectiveness of Fuel Utilization in a Process

 

348

   

 Literature Cited

 

353

Chapter 10:

 

Some Methods of Reducing Sulfur Oxides From Power Plants

 

354

   

 Assessment of the Potentials for Improved Efficiency in the Conversion of Fuel to Electricity

 

355

   

 Shift to Nuclear Generation as Rapidly as Possible

 

359

   

 Shift to Lower Sulfur Fuels

 

360

   

 Remove Sulfur from Coal Before and During Combustion

 

368

   

 Shift Fuel Consumption from Electricity to Pipeline Grade Gas Made from Coal

 

381

   

 Footnotes

 

383

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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Chapter 11:

 

Flue Gas Desulfurization

 

385

   

 Introduction

 

385

   

 Lime Scrubbing for Medium and High Sulfur Coal

 

394

   

 Limestone Scrubbing for Medium and High Sulfur Coal

 

419

   

 Environmental Considerations

 

429

   

 Water Pollution

 

434

   

 Particulate Removal Efficiencies

 

435

   

 Costs of Flue Gas Desulfurization Systems

 

440

   

 Institutional Barriers to the Application of Sulfur Oxide Control Systems

 

454

   

 Acknowledgements

 

457

   

 Footnotes

 

457

   

Appendix 11-A 

 

458

   

 Control of Emissions of Sulfuric Acid Vapor and Mist

 

458

   

Appendix 11-B 

 

474

   

 Literature Cited

 

480

Chapter 12:

 

Control of Ambient Sulfur Dioxide Concentrations with Tall Stacks and/or Intermittent Control Systems

 

485

   

 Introduction

 

485

   

 Tall Stacks and ICS Programs

 

488

   

 Legal Background

 

493

   

 Assessment of the Technology

 

497

   

 Enforcement

 

522

   

 Statement of Findings and Conclusions

 

527

   

 Footnotes

 

533

   

 Literature Cited

 

535

 

 

Section 3: Analysis of Alternative Emissions Control Strategies

 

539

Chapter 13:

 

Analysis of Alternative Emissions Control Strategies

 

540

   

 Introduction and Scope

 

540

   

 Alternatives for Emissions Control

 

543

   

 Methodology

 

546

   

 The Emissions Control Decision for Representative Electric Power Plant

 

549

   

 An Overview of the Assessment of Costs and Benefits for a Representative Plant

 

551

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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INTRODUCTION AND SUMMARY

In September 1974, the National Research Council presented the report Air Quality and Automobile Emission Control to the U.S. Senate Committee on Public Works. That report examined the health effects of a number of pollutants (carbon monoxide, nitrogen oxides, oxidants, sulfur oxides, and particulates), reviewed the state of knowledge about the relationship between emissions of pollutants from automobiles and ambient air quality, and presented a discussion and analysis of the costs and benefits of automobile emission control. At hearings held by the Senate Committee, Senator Jennings Randolph (D., W.Va.) indicated a need for a similar review of sulfur-related pollutants from stationary sources. The Senator formally requested such a review in a letter of September 18, 1974 to Dr. Philip Handler, President of the National Academy of Sciences (see p. xiv). Dr. Handler replied on October 24 (see pp. xv–xvi). Although Senator Randolph’s request related only to sulfur oxides and particulates, it seemed useful and appropriate to include in the report a review of the extent of the problem of nitrogen oxide emissions from stationary sources and the techniques available for abatement of these emissions as well.

The Environmental Protection Agency has established ambient air quality standards for certain air pollutants. A table of currently mandated air quality standards can be found on p. xliii. The states were to devise implementation

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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plans which would reduce emissions so as to achieve these ambient air quality standards. EPA has also established standards of performance for new stationary sources; the standards for fossil fuel-fired steam generators can be found on p. xliv.

The control of sulfur oxide emissions from stationary sources is clearly a controversial topic. A glance at the daily newspapers demonstrates the extent of the controversy. Full page advertisements debate the virtues and deficiencies of systems of control, and the debate is made all the more immediate by urgent problems of energy supply and demand.

The task of the National Research Council has been to examine and evaluate the existing data. The goal has been to present to the Public Works Committee scientific judgments concerning the state of knowledge of the effects of emissions from stationary sources and of the techniques and strategies available for their control.

Information concerning neither the magnitude of the deleterious effects of sulfur oxide emissions, nor the atmospheric chemistry of sulfur oxides, nor the control of emissions has been found to be sufficiently reliable and extensive to permit resolution of the attendant controversies with a high degree of confidence. This report indicates that there are considerable uncertainties concerning the extent of the harmful effects of sulfur oxide emissions, the molecular species responsible for the effects, and the specific relationships between point source emissions of sulfur dioxide and regional patterns of formation, dispersion, and deposition of sulfates. Based upon the Community Health and Environmental Surveillance System studies conducted by the U.S. Environmental Protection Agency, there appears to be an association between a level of sulfate of 8 to 12 micrograms/cubic meter in the ambient air and adverse health effects in elderly persons with heart and lung disease and persons with asthma. Somewhat higher levels of sulfate (13 to 15 micrograms/cubic meter) appear to be associated with increased prevalence of chronic bronchitis in adults, increased acute lower

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respiratory disease and decreased lung function in children, and increased frequency of acute respiratory disease. Within these broad categories practically every individual would be included, inasmuch as most persons suffer from symptoms of respiratory disease at some time. The studies upon which these statements are based need further verification.

Although recent information concerning the performance of scrubbers intended to remove sulfur dioxide from flue gases is encouraging, some additional experience, with opportunity for design improvement, would greatly enhance public and private confidence in the large and costly decisions which must be made. Nevertheless, there are strong suggestions that the benefits of abating emissions of sulfur oxides would be substantial and, for certain plants which affect areas where there already are high ambient concentrations of sulfur dioxide and suspended sulfate, substantial abatement costs would appear justifiable. Accordingly, Part Two of this report recommends that high priority should be given to emission abatement for power plants in and close upwind of these areas and that lower priority should be given to power plants far upwind from these areas.

This report suggests that there is a need for flexibility of response which can take into account specific conditions at each power plant. Innovative instruments of policy should be considered with particular attention to their application in conjunction with various technologies for control of pollutants. For example, an emissions charge on sulfur oxides might be contemplated as an immediate incentive to undertake control activities.

The studies and findings in this report on Air Quality and Stationary Source Emission Control taken with the earlier examination of Air Quality and Automobile Emission Control emphasize the need for an integrated study of air pollutants, their sources, and their effects. Synergistic effects among pollutants were discussed in the Automobile Emission Report which noted the need to understand the health effects of various combinations of pollutants. The present report also indicates the need for a

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
×

better understanding of the effects of both sulfur oxides and nitrogen oxides on the acidity of precipitation, and it notes the dependence of atmospheric chemical reactions of sulfur-related pollutants upon the concentration of other pollutants (such as oxidants and nitrogen oxides) in the ambient air.

The major emphasis in this report is upon the effects and control of sulfur oxide pollutants, and useful and important conclusions can be drawn from the analyses. But the report would be remiss if it did not remind the reader that examination of part of a larger problem may lead to partial, perhaps even incorrect, solutions. It may be necessary to implement partial solutions, but ultimately the effects of all pollutants and the techniques for their abatement, individually and in combination, must be examined so that a coherent program for the control of air pollution may be developed.

SCOPE OF THE REPORT

The Commission on Natural Resources has reviewed all of the contributions to this report and is responsible for the findings and recommendations recorded in the summary.

Part One: Health and Ecological Effects of Sulfur Dioxide and Sulfates (Chapters 1 through 5) was prepared under the auspices of the Assembly of Life Sciences. This part of the report updates work included in the September 1974 report on Air Quality and Automobile Emission Control (Chapter IV of Volume 2) which examined effects of airborne particles and sulfur oxides on health. Chapters 1 through 4 were prepared for the ALS by Bernard Goldstein of the New York University Medical School; Chapter 5 was contributed by Ian Nisbet of the Massachusetts Audubon Society. John Redmond, Jr., served as staff officer to the Assembly of Life Sciences.

Part Two: Strategies for Controlling Sulfur-Related Power Plant Emissions (Chapters 6 through 13) was developed under the auspices of the Committee on Public Engineering Policy, Assembly of Engineering. To prepare this part, COPEP established a Review Committee on Air

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
×

Quality and Power Plant Emissions (see Part Two) under the chairmanship of Donald Katz of the University of Michigan. Strategies for the control of sulfur oxides and particulates are examined in detail in this part of the report. The impact of such strategies on both urban and rural sulfur dioxide and sulfate concentrations is emphasized along with the timing and costs of implementing them. Part Two focuses on air pollution problems associated with electric utility generation, particularly in the northeastern United States, the geographical area most affected by coal-burning power plants. Sections of this part are based on the work of individual consultants or staff members; the members of the Committee reviewed the working drafts and provided overall guidance. The discussion of the relationship of emissions to ambient air quality in Chapter 6 is based on the work of John Trijonis, of TRW, Inc. The acid rain discussion in Chapter 7 is the work of Ian Nisbet, who was also a member of the Review Committee. Chapter 8 on efficient pricing is drawn from work by Alfred Kahn, also a Review Committee member. Elias Gyftopoulos of MIT and T.F.Widmer of Thermo Electron Corporation drafted Chapter 9. Chapter 10 on improving conversion efficiency, fuel shifting, and fuel preparation is based on the work of Harry Perry of Resources for the Future. Chapter 11, flue gas desulfurization, draws on the work of Leigh Short of the University of Massachusetts and Arthur Squires, a Review Committee member. The discussion of tall stacks and intermittent control systems in Chapter 12 was prepared by Robert Dunlap of Carnegie Mellon University; and the discussion of alternative control strategies in Chapter 13 draws on analyses carried out for the Review Committee by D.Warner North and Miley Merkhofer of the Stanford Research Institute. These analyses were used by the Review Committee in drafting the section entitled “Part Two in Brief” and in forming its conclusions; and because of their scholary merit and pertinence to the subject matter of this study, the contributions of the various consultants and committee members were considered by the Review Committee to be

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
×

essential inclusions in the report. Laurence I.Moss and Ronald J.Tipton served as staff officers to the Review Committee.

Part Three: Control of Nitrogen Oxides from Stationary Sources (Chapters 14 and 15) was prepared under the direction of the Commission on Natural Resources. It examines the relative contribution of various sources of nitrogen oxide emissions and reviews the techniques of nitrogen oxide emission control. (The health effects of nitrogen oxides and their reaction products were discussed in the September 1974 report on Air Quality and Automobile Emission Control and are not considered in this report on stationary source control. Trends in nitrogen oxide and oxidant air quality were also discussed in the earlier report and are not repeated here.) The discussions of nitrogen oxide sources in Chapter 14 and of tall stacks and intermittent control for nitrogen oxides in Chapter 15 are based on analyses by John Spengler, Anthony Cortese, and Douglas Dockery of the Harvard School of Public Health. The examination of control techniques in Chapter 15 is based on the work of Adel Sarofim and Richard Flagan of the Massachusetts Institute of Technology. Raphael G.Kasper served as staff officer to the Commission on Natural Resources.

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SUMMARY

This summary highlights the principal findings and conclusions of the report. The reader is encouraged to examine the basis for each of the findings and conclusions as it is presented in detail in the body of the report.

SUMMARY OF PART ONE: HEALTH AND ECOLOGICAL EFFECTS OF SULFUR DIOXIDE

  1. Adverse consequences to health from combustion of sulfur-containing fossil fuels cannot be simply ascribed to any one sulfur oxide acting alone. (The term sulfur oxide is used to mean the family of compounds including sulfur dioxide, sulfur trioxide, sulfuric acid, and various sulfate salts. Sulfur dioxide is the main sulfur oxide directly emitted by fossil fuel combustion.) Sulfur dioxide itself appears unlikely to be the direct cause of excess morbidity and mortality associated with stationary source fossil fuel combustion. However, levels of sulfur dioxide close to the current ambient air quality standards may be responsible for deleterious effects on health when inhaled in combination with respirable (very small) particulate matter or the oxidant air pollutant ozone. Oxidation products of sulfur dioxide, including sulfuric acid and suspended particulate sulfates, are more toxic than the parent compound and appear likely to be responsible for a substantial portion of adverse effects on health associated with stationary source combustion of fossil fuels. (See Chapter 3.)

  2. The processes governing the conversion in the atmosphere of sulfur dioxide to sulfuric acid and suspended sulfates are complex and

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incompletely understood. It is clear, however, that the oxidation of sulfur dioxide is accelerated in the presence of other pollutants, particularly trace metals derived mainly from stationary source fossil fuel combustion, and components of photochemical smog derived primarily from automotive emissions. (See Chapter 2.)

  1. The specific chemical species responsible for toxicity have not been identified, and the levels of pollutants necessary to cause toxic effects have not been determined. This hampers the exact determination of the morbidity and mortality resulting from sulfur oxides. The use in epidemiological correlations of monitoring data for total suspended particulates and sulfur dioxide has undoubtedly led to imprecision inasmuch as these two measurements do not directly assay the causative agents. It is possible that the use of these indicators may have led to underestimation or overestimation of the health consequences of sulfur oxide or respirable particulate matter, but most likely underestimation. Particles in the respirable size range undoubtedly play a role in morbidity. (See Chapter 2.)

  2. In the next few years additional information will probably be available that will permit establishment of rational air quality standards for respirable particulate matter and suspended sulfates in order to protect the public. This will require substantial advances in monitoring and analytical techniques as well as improved assessment of health hazards. (See Chapter 2.)

  3. Review of the available data suggests that it is reasonable to predict that an increase in morbidity and mortality of susceptible individuals would result from an increase in ambient sulfur dioxide to levels appreciably above the current air quality standard. (At present, levels generally do not exceed this standard.) Susceptible groups represent a substantial fraction of the U.S.

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population and include children, the elderly, asthmatics, and individuals with chronic cardiovascular and pulmonary disease. (See Chapter 4.)

  1. In view of the societal and economic impact of controlling sulfur oxide emissions, it is of major importance to quantify the health effects associated with sulfur oxides and the benefits to be gained by avoiding those effects. A number of attempts to do so have been made, and they are reviewed in this report. Analysis of data developed from the CHESS studies of the Environmental Protection Agency provides some guidance in defining the limits of the problem, but these and other currently available data on the health effects of sulfur oxides should be viewed with caution. (See Chapter 4.)

  2. Definition of a no-effect level (threshold) for the acute effects of sulfur oxides is difficult. It is not clear that there is any level of these pollutants above background that will not have an acute effect on the most susceptible individuals. However, it is beyond present knowledge to state whether acute responses to low levels are non-injurious adaptive responses or are responses which, often repeated, might lead to eventual respiratory impairment. High priority should be given to research evaluating the long-term physiological effects of sulfur oxide air pollution. (See Chapter 2.)

  3. Sulfur oxide emissions from catalyst-equipped automobiles may take the form of sulfuric acid mist or suspended sulfates. Since the emissions are at ground level, they are likely to be encountered by individuals. If an increasing proportion of the automobile fleet is catalyst equipped, these sulfur oxide emissions may constitute an appreciable part of the total sulfur oxides inhaled and a significant proportion of the threat to health from these compounds. As yet there are no direct experimental data on the health effects of the particular sulfur oxides emitted from automobiles. In the absence of experience and

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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sufficient data, we are unprepared to compare quantitatively the possible deleterious health effects arising from catalyst operation with the health benefits to be gained by the oxidation of hydrocarbons and carbon monoxide in automotive emissions. (See Chapter 2.)

  1. The visible direct effects of high concentrations of sulfur dioxide on susceptible species of plants have been recognized for many years. Knowledge of whether lower concentrations decrease productivity of natural flora and fauna is very meager. The ecological consequences of the increasing acidity of precipitation deserve thorough study. The increase in acidity of precipitation appears to be related to increased emissions of sulfur dioxide and nitrogen dioxide although the exact relationship needs further study. (See Chapter 5.)

  2. Identifiable effects of acid precipitation include acidification of soils, reduction in forest productivity, and depletion of fresh water fish populations. Materials, buildings, and various substances are degraded by sulfur oxides in the air and by acid precipitation. The full impact of these effects may not be felt for a number of years. Rough estimates of their likely magnitude suggest that they are relatively modest in economic terms, but they may also involve loss of recreational opportunity and aesthetic values. The possibility of additional effects, such as reduction in agricultural productivity or extensive injury to valuable ornamental plants, cannot be dismissed. (See Chapter 5.)

  3. Atmospheric hazes, attributable in large part to fine particulates including sulfates, are widespread in the eastern United States during the summer; their frequency appears to be increasing as emissions increase, and they may have effects on weather and climate. (See Chapter 5.)

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  1. With the protection of human health as the goal, it is desirable to limit the atmospheric emission of sulfur oxides and respirable particulate matter. (See Chapter 4.)

SUMMARY OF PART TWO: STRATEGIES FOR CONTROLLING SULFUR-RELATED POWER PLANT EMISSIONS

Sulfur Oxide Emissions and Abatement Techniques
Reasons for Reducing Emissions of Sulfur Oxides
  1. Part One of this report points out that adverse consequences to health from combustion of sulfur-containing fossil fuels cannot be ascribed to any single sulfur oxide acting alone, and that sulfur dioxide itself appears unlikely to be the sole cause of excess morbidity and mortality associated with pollution in the form of sulfur oxides and suspended particulate matter. In particular, certain oxidation products of sulfur dioxide, including sulfuric acid and certain suspended particulate sulfates, are more toxic than the parent compound and may be responsible for a substantial portion of the adverse health effects associated with sulfur oxides and particulate pollution, a portion of which arises from stationary source combustion of fossil fuels. In the study of control strategies in Part Two of this report, the concentration of airborne particulate sulfates has been used as an index of pollution hazard. (See Part I.)

  2. Within a large region such as the northeastern United States, particulate sulfate concentrations in the atmosphere are related to regional emissions of sulfur dioxide, which is converted to sulfates after emission. Because sulfur dioxide and sulfates may be transported long distances before being removed from the atmosphere, and because during the transport period there is conversion of sulfur dioxide to sulfates, there is not always a close relationship between ambient concentrations of sulfates and emissions of sulfur dioxide in the

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immediate vicinity. For example, in some rural areas in the Northeast where there are comparatively low sulfur dioxide emissions and low ambient sulfur dioxide levels, ambient sulfate concentrations are substantially above background levels. (See Chapter 6.)

  1. Concentrations of sulfates in airborne particulate matter are difficult to measure but appear to have increased. The amounts of sulfates deposited in rainfall have been increasing in parallel with the increase of emissions of sulfur dioxide. The acidity of precipitation in the eastern states has also been increasing; this is attributable to an increase in emissions of both sulfur dioxide and nitrogen oxides. (See Chapters 6 and 7.)

  2. In addition to the adverse effects on health from these pollutants, there are damages to materials, decreases in property values, and impairment of agriculture, forestry, and ecosystems. These effects point to the desirability of controlling the amount of produced sulfur compounds emitted into the atmosphere. (See Chapters 5 and 7, and Appendix 13-E.)

Power Plants a Major Source of Sulfur Oxide Emissions
  1. Steam electric generating plants that burn coal are major sources of sulfur oxide emissions, especially in the northeastern U.S. In this region, the quantity of anthropogenic sulfur oxides almost certainly exceeds the amount emitted from natural sources such as decaying vegetation. On a nationwide basis, more than 50 percent of total anthropogenic sulfur oxide emissions are produced through combustion of coal in power plants; in some regions the percentage is much higher. Other sources of sulfur oxides include space heaters, smelters, and industrial boilers. Information recently brought to the Committee’s attention suggests that oil-fired combustion, particularly in small combustion devices such as home

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furnaces, appears to be an important source of sulfuric acid emissions. Coal fired electrical generation may increase as much as 100 percent, possibly more, over the next decade. The resulting power plant emissions, if not controlled, may lead to increases in ambient sulfate levels in urban areas on the order of 10 to 40 percent as well as to increases in ambient sulfur dioxide levels and in the acidity of precipitation. (See Chapters 6 and 7, and Appendix 11-A.)

Emissions from Power Plants Depend in Part on the Use of Electricity, Which Depends on Many Factors.
  1. The Review Committee recognizes the national determination to decrease U.S. dependence upon imported petroleum fuels. Achievement of this goal is likely to entail a substantial increase in the use of coal for the generation of electricity. There are two reasons for this: more electricity will be required to permit reductions in the use of oil, and a larger fraction of the electricity produced will be generated from coal. The shortage of natural gas will also result in increased use of coal for the same reasons. The consequence of these changes could be a large increase in sulfur dioxide emissions. (See Chapter 6.)

  2. A major current use of oil and gas is for domestic and office space heating. Electrical energy could replace the direct use of oil and gas for space heating, but this could result in additonal burning of coal and accompanying emissions of sulfur oxides. Therefore, if such a change were contemplated, it would be desirable to employ space heating technology which would make efficient use of electricity. A shift to the use of electrical resistance heating would increase the overall consumption of fuel; however, there would be little, if any, increase in the overall consumption of fuel if the shift were, instead, to electrically-powered heat pumps, where local

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weather conditions make this technically possible. Moreover, it is estimated that the total capital investment (at the point of generation as well as at the point of use) required for the heat pump system is less than that for the electrical resistance heating system. The alternative of producing combustible gas from coal to serve the heating market also appears to require substantially less capital and less total fuel consumption than electrical resistance heating. There are additional options for meeting some of the nation’s space and water heating requirements, e.g., solar energy and possible new domestic petroleum and gas resources. Although each of these options will probably take at least three to five years before it can add significantly to incremental supplies, an examination of them should be included in a comprehensive analysis. (See Chapter 9.)

  1. Conservation and improved fuel use can substantially reduce the rate of growth in demand for electrical energy and in this way reduce the amount of coal used and the sulfur dioxide emitted in its generation. Improvements in fuel use can be accomplished by: (1) improved effectiveness of electrical apparatus used in the residential, commercial, and industrial sectors; and (2) on-site generation of electricity as a by-product of certain industrial processes. (See Chapter 9.)

  2. In a market economy, where consumption decisions are made by individual purchasers, economic efficiency requires that the price reflect the incremental cost of supply to society. This means, in an expanding industry, that price should equal the cost of obtaining new or replacement supplies of the resource, including social and environmental costs. If such prices are not charged, then either too much or too little of the resource will be used in relation to other resources. The rate at which fuel-saving technology will actually be applied depends upon the rate of pay-back for capital invested in such technology. One critical factor currently retarding the appli-

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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cation of new and more efficient technology is the manner in which fuel and electricity costs are determined. The price a user pays for energy is generally based on average costs of production rather than on incremental costs, which tend to be much higher. Similarly, the higher cost of supplying electricity during hours of peak system demand is not sufficiently reflected in rate structures. A fuller application to electricity rates of these incremental cost pricing principles could make a substantial contribution to conservation and thereby to reducing sulfur oxide emissions. (See Chapter 8.)

Flue Gas Desulfurization (FGD) Technology
  1. For power plants that burn low-sulfur (less than 1 percent sulfur) coal, either lime or limestone scrubbing is the most effective method now available for reducing emissions of sulfur dioxide in flue gases. Emissions of sulfur dioxide from such sources can be reduced by at least 90 percent with these methods. Successful operation has been demonstrated on commercial scale modules of 115 Mw for lime scrubbing and 170 Mw for limestone scrubbing. (See Chapter 11.)

  2. For power plants that burn medium or high-sulfur coal, lime scrubbing is the most effective near-term method for reducing emissions of sulfur dioxide in flue gases. Reductions of at least 90 percent have been achieved with this method. Successful operation of a lime scrubber in the desirable closed loop mode (i.e., with no release to the environment of water from the process) in a power plant burning medium-sulfur, low-chlorine coal has been demonstrated on a commercial scale. The demonstration power plant is a peaking unit producing flue gas equivalent to about 100 Mw capacity. Although it ordinarily operates intermittently, in these trials it has operated continuously, following changes in load typical of many utility boilers. The 100 Mw size is typical of the module that designers may provide

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in multiples for dealing with the flue gas from boilers of much larger capacity. The chlorine content of coal affects successful scrubber operations for at least three reasons: (1) it contributes to the acidity of sludge slurries; (2) it retards the rate of oxidation of calcium sulfite to calcium sulfate in slurries; and (3) it leads to materials corrosion in stack equipment as a result of hydrogen chloride formation. Successful operation of a lime scrubber on flue gases arising from the burning of a high-sulfur coal of medium or high chlorine content has been observed on a bench and pilot-plant scale (1.0 and 10 Mw equivalent capacity), also in a closed-loop mode. Experience on a commercial scale can and should be obtained quickly for medium- and high-sulfur coals containing chlorine beyond 0.04 percent. This experience is necessary to resolve the question of the commercial availability of lime scrubbing technology for all coals. That this question will be resolved favorably is a matter for engineering judgment in light of the available chemical knowledge and performance comparisons. Some of the Committee members judge the probability to be 90 percent, while one member judges it to be 70 percent. (See Chapter 11.)

  1. The committee is well aware of the problems which have been experienced in early installations of flue gas desulfurization processes. This discouraging experience has caused many in the electric utility industry, as well as others, to doubt the feasibility of the technology. The Committee finds, however, that there has been rapid advance in the understanding and application of scrubbing technology especially in the past year, and urges those who are skeptical to review this recent experience. If scrubbers ordered today are to operate as reliably as other components of the power generating system, they will require very careful engineering and initial “trouble shooting” operating procedures which may be extensive. There is a reasonable expectation that, in the near future, scrubbers will be available for purchase as routine components of power systems covering a wide

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range of specific conditions, provided a vigorous development program is pursued. (See Chapter 11.)

  1. The large quantity of waste by-product associated with lime and limestone scrubbing is a disadvantage of these processes. Sludge storage using lined ponds has been successful for lime and limestone flue gas desulfurization installations. The availability of space near the power plant is an important factor in determining the feasibility of sludge storage using lined ponds and may substantially increase the cost of retrofitting plants already located in urban areas because of the need for transportation of sludge. The problem of ultimate disposal is being attacked by fixation of sludge to produce a material of low permeability and leachability, suitable for landfill and as a base for roads. Tests on commercial-scale modules are now underway in several locations. The results are reported to be promising. (See Chapter 11.)

  2. Installation of a lime scrubbing process for a new power plant burning high-sulfur eastern coal will require an added capital investment of about $100/kw (all costs in 1974 dollars). The investment could be as low as $60/kw and as high as $130/kw. Added operating costs, including capital charges, will range from 2 to 5 mills/kwh plus a cost of about 1 mill/kwh for energy loss and capacity derating. This is 15 to 30 percent of the total cost of generating power at a new plant. Sludge fixation, or sludge transportation, if needed, will add to these costs. (See Chapters 11 and 13.)

  3. A longer term approach to the problem of sulfur emissions involves conversion of the sulfur dioxide into elemental sulfur and regeneration of the scrubbing liquor. This would eliminate the problem of disposal of large quantities of sulfites and sulfates of lime and, instead, provide easily stored and commercially valuable elemental sulfur. There is successful commercial operating experience with regenerable

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flue gas desulfurization processes on stack gases arising from the combustion of oil. There is no commercial operating experience using a regenerable process to treat stack gases arising from combustion of high-sulfur coal. A few such plants are under construction, and large-scale plant testing of such systems is now underway. Because the potential advantages of regenerative processes are significant, a careful evaluation of the desirability of increasing the funds being devoted to their development is warranted. (See Chapter 11.)

  1. About 70 percent of existing plant capacity may be retrofitted with lime or limestone FGD systems. The cost of retrofitting is normally 25 to 30 percent higher than the cost of installing scrubbers on a new plant of equal capacity. Older, smaller existing plants are more difficult and costly to retrofit than newer, larger existing plants. (See Chapter 11.)

Use of Low-Sulfur Coal and Washing of High-Sulfur Coal
  1. Most of the coal from eastern resources has a high sulfur content. Of the more limited eastern low-sulfur coal, a large fraction is held by owners who have dedicated these resources to metallurgical use. Washing of the high-sulfur eastern coals could, on average, reduce their sulfur content by about 40 percent (i.e., from a sulfur content of 3.5 percent to 2.1 percent). The amount of such reduction depends on the characteristics of the particular coal used. Coal washing will be of some benefit in reducing emissions of sulfur oxides. Conventional physical cleaning will reduce the total sulfur emitted by power plants by significant amounts (of the order of 40 percent overall) but it will not, in general, result in coals with a sulfur content meeting the New Source Performance Standards for SOx. However, coal preparation can reduce the sulfur content to levels that are permitted by the State

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Implementation Plans for existing plants in some rural areas. (See Chapter 10.)

  1. Large quantities of low-sulfur coal are found in the western U.S. Although new plants can be designed to burn these coals efficiently, in existing plants the boilers must be derated (i.e., operate at less than design capacity) to operate satisfactorily. Moreover, the transport of low-sulfur western coals to eastern markets will require construction of major additonal transport facilities. (See Chapter 10.)

  2. By shifting available low-sulfur coal away from plants that could burn higher sulfur coal and still meet ambient sulfur dioxide standards to plants in regions not meeting ambient standards for sulfur dioxide, some improvement in compliance with applicable ambient air quality standards for sulfur dioxide could be achieved. However, such shifting of low-sulfur coal will not reduce the total amount of sulfur in the atmosphere; therefore, this strategy should be considered at best an interim measure only. The potential for increasing ambient sulfate concentrations in downwind areas should be carefully assessed before any such strategy is implemented. (See Chapters 6, 7, 10, and 13.)

  3. Caution must be exercised in the substitution of low-sulfur coal in existing power plants, since there is a resultant risk of increasing emissions and ambient concentrations of particulate matter. The efficiency of devices for the removal of particulate matter, especially electrostatic precipitators, is decreased for fly ash from low-sulfur coals. Hence, a decrease in sulfur dioxide by fuel substitution may result in greater emissions of particulate matter, including any trace metals present in the coal. Such problems could be minimized by appropriate modification of equipment or process conditions or both. (See Chapter 10.)

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Tall Stacks and Intermittent Control Systems (ICS)
  1. Tall stacks and/or intermittent control systems make it possible to meet ambient sulfur dioxide standards in carefully defined situations. The attractiveness of these systems lies in their low operating and capital costs, estimated to be 0.15 to 0.4 mill/kwh and $4 to $10/kw, respectively. The Committee does not recommend their use unless it is for carefully defined situations for an interim period until other strategies (e.g., flue gas desulfurization, low-sulfur fuel) can be implemented, or until further data are accumulated which would justify making them permanent. The application of tall stacks and/or intermittent control systems will not reduce total emissions of sulfur oxides to any significant degree; thus, this strategy does not decrease the total amount of sulfate in the regional atmosphere. The potential for increasing ambient sulfate concentrations in downwind areas should be carefully considered in advance, and effects on ambient concentrations monitored, if such a strategy is implemented. (See Chapter 12.)

Recommended Decisions and Decision Processes for Abatement Strategies
  1. Methodology is available for analyzing decisions among abatement alternatives: the deleterious consequences of sulfur oxide emissions to human health, ecological systems, material property, and aesthetic valued should be evaluated and compared (for each power plant in a region) with the additional cost imposed on the generation of its electricity by the abatement methods. The calculation thus involves a comparison of marginal cost with marginal benefit for each power plant within the regional system of electric generation and air quality. However, conclusions drawn from the application of this methodology must of necessity reflect the adequacy of the information available at the time of application; at the present time uncertainty in

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many critical variables and relationships severely limits the conclusions that can be drawn as to the best strategy alternatives for controlling sulfur oxide emissions. By assessing in probabilistic terms the respective costs and benefits for various alternative strategies, the methodology can indicate where, on the basis of the limited information available, stringent control is desirable and where more information would be advisable before a commitment to a particular emissions control strategy is made. (See Chapter 13.)

  1. There are considerable uncertainties concerning the extent of the harmful effects of sulfur oxide emissions, and concerning the specific relationships between point source emissions of sulfur dioxide and regional patterns of formation, dispersion, and deposition of sulfates. Any policy adopted now, therefore, should be reviewed periodically in the future and may have to be changed as a result of new findings. Nevertheless, the calculations shown in Chapter 13 suggest that the benefits of abating emissions of sulfur oxide may exceed the costs substantially for plants which affect areas where there are already high ambient concentrations of sulfur dioxide and suspended sulfates, such as urban areas in the Northeast. In addition, the Committee places importance on considerations of prudence; the consequences of an error in judgment which led to substantial damage to human health would be more serious than an error which led to an economic misallocation. Accordingly, the Committee recommends that high priority should be given to emission abatement from power plants in and close upwind of urban areas. Although the analysis in Chapter 13 indicates that lower priority should be given to power plants far (of the order of 300 miles) upwind from major cities, it also indicates that external costs imposed by emissions from these plants may be substantial. Since the capacity for installing flue gas desulfurization systems is limited, there will be a continuing opportunity to review the costs and benefits of

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emission controls for plants now assigned to a low priority. (See Chapter 13.)

  1. National capacity to produce stack gas scrubbing equipment is limited. Further advances in applicable technology are expected to occur in the next few years. Scrubbing equipment should be installed first in those situations where its additional benefits in emissions abatement are judged to be highest with respect to its additional costs. All new plants, including those able to meet New Source Performance Standards without the use of scrubbers, should at least be constructed so as to permit subsequent retrofitting of flue gas desulfurization systems, since the cost of allocating space for that purpose is low. In time, the increase in coal use and further information on the effects of sulfur oxide emissions may indicate a need for a greater degree of emissions reduction. (See Chapter 13.)

The Value of Resolving Uncertainties on the Effects of Sulfur Oxide Emissions
  1. Decisions about control strategies depend upon the information available at the time the decisions are made. A better understanding of the effects of suspended sulfates on health and of the chemistry of the atmospheric conversion of sulfur dioxide to sulfate could have a significant effect upon future decisions about sulfur oxide emissions abatement. Improving the available information about these aspects of sulfur emissions has an expected value on the order of hundreds of millions of dollars a year, which is at least ten times greater than the cost of a research program to resolve these uncertainties in approximately five years. (See Chapter 13.)

  2. Current assessments of the benefits of sulfur oxide emissions reduction for human health, ecological systems, materials, and aesthetic values could be greatly improved. Substantial efforts should be made to develop

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improved models and data for use on a case-by-case basis to improve decisionmaking on emissions control strategy alternatives. There is also a need to investigate the distribution of costs and benefits among different individuals within society, and the effects of emissions controls and pricing policy on this distribution. (See Chapter 13.)

SUMMARY OF PART THREE: CONTROL OF NITROGEN OXIDES FROM STATIONARY SOURCES

  1. The quantity of nitrogen oxide produced by human activity throughout the world is on the order of 10 percent of the nitrogen oxide produced from natural sources. However, the anthropogenic nitrogen oxide emissions are concentrated in populated areas and are thus of concern in pollution control programs. (See Chapter 14.)

  2. National nitrogen oxide emissions have grown at an average rate of over 4 percent per year for the last three decades. (See Chapter 14.)

  3. At present, stationary source fuel combustion accounts for about half of all U.S. nitrogen oxide emissions, and electric power generation represents 24 percent of U.S. nitrogen oxide emissions. (See Chapter 14.)

  4. The nitrogen oxide emission rate per unit heat produced is greater from coal than from either oil or natural gas. Therefore, conversion of existing plants to permit the burning of coal and use of new coal-fired electric generating plants would increase nitrogen oxide emissions at a greater rate than that projected from historic trends. (See Chapter 14.)

  5. Transportation is the second largest source category, contributing 35.4 percent of the U.S. total nitrogen oxide emissions. (See Chapter 14.)

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  1. Projections of future nitrogen oxide emissions demonstrate that, if present statutory standards are adhered to, stationary sources will contribute an increasing percentage of total nitrogen oxide emissions through 1990. (See Chapter 14.)

  2. There are geographical differences in nitrogen oxide emissions which reflect the distribution of industry, electric power generation, and population. Fifty-six percent of the national nitrogen oxide emissions are produced in the northeast states (EPA Regions I, II, III, and V). (See Chapter 14.)

  3. Thirty-nine percent of all U.S. nitrogen oxide emissions are generated in the 10 largest urban areas. In fact, 25 percent of the total U.S. emissions are produced in the five largest urban areas. This reflects the dominance of stationary fuel combustion and industrial process emissions. Only 22 percent of the nation’s transportation-related nitrogen oxide is emitted from the 10 largest urban areas. Thus, in many urban areas, nitrogen oxide emissions from stationary sources are the dominant factor in determining ambient concentrations of this pollutant. (See Chapter 14.)

  4. There are considerable uncertainties in the 1972 nitrogen oxide emissions data as reported by the National Emissions Data System (NEDS). For example, examination of the data indicates that industrial process losses are probably significantly underestimated. (See Chapter 14.)

  5. Typically, within combustors nitrogen oxide is formed in localized, high-temperature regions by the oxidation of both atmospheric nitrogen (thermal NOx) and nitrogen that may be contained in the fuel (fuel NOx). (See Chapter 15.)

  6. The formation of nitrogen oxide in combustion systems can be suppressed, with varying degrees of success, by reducing the

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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oxygen content and temperature in the localized regions of the furnace contributing to emissions, usually in the vicinity of the flame. Reductions in the oxygen content in the flame zone reduce the emissions of both fuel and thermal NOx; reductions in temperature, however, produce significant reductions in only the thermal NOx. (See Chapter 15.)

  1. Methods that have been used to reduce the temperature in the combustor include: (a) injection of cooled combustion products, steam, or water into the flame volume; (b) reduction of the temperature to which combustion air is preheated; and (c) extraction of heat from the flame volume. (See Chapter 15.)

  2. Methods for reducing the oxygen content in the flame zone involve lowering the volume of air supplied to the burners by reducing the overall air/fuel ratio to the combustor (low-excess-air firing) or by reducing the air/fuel ratio for some burners without reducing the overall air/fuel ratio (staged combustion). (See Chapter 15.)

  3. Low-excess-air-firing, staged combustion, flue-gas recirculation, water injection, and reduced air preheat are control techniques that have been successfully demonstrated on utility boilers. The latter two methods, however, have an associated, usually unacceptable, penalty in thermal efficiency. Using combinations of the techniques listed above, an average reduction in nitrogen oxide emissions of 60 percent has been achieved for gas-fired utility boilers, 48 percent for oil-fired boilers, and 37 percent for coal-fired boilers. (See Chapter 15.)

  4. The applicability of combustion process modification to existing furnaces must be evaluated on a case-by-case basis. In general, boilers can be adapted for low-excess-air firing and staged combustion without major modification. Flue-gas recirculation may be

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
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impractical on some existing units. (See Chapter 15.)

  1. The capital costs of nitrogen oxide emission reduction in utility boilers vary widely with specific installation size and design. They range from under $0.50/kw for staged combustion to $6.00/kw for flue-gas recirculation on existing units, and from near zero for staged combustion to $4.00/kw for flue gas recirculation on new units. (See Chapter 15.)

  2. The level of control achievable on industrial boilers is close to but not as great as that attainable with utility boilers. (See Chapter 15.)

  3. Reduction in nitrogen oxide emissions from stationary engines is possible, although such reduction is often accompanied by significant increases in fuel consumption. New engine designs may produce substantial reductions in nitrogen oxide emissions without increasing fuel consumption, but futher development of such designs is required. (See Chapter 15.)

  4. Fluidized bed combustion of coal provides a potential alternative to current utility boiler design. Tests on laboratory and pilot-scale fluidized bed combustors have yielded emissions that meet the current standards for new coal-fired units. Tests on larger scale units are needed to establish practical emission levels for commercial applications. (See Chapter 15.)

  5. The only intermittent, control strategy that appears practical for NOx emission reduction is load switching of electric power generation. Load switching has limited applicability because of the variability in the contribution of electric power generation to local emissions. (See Chapter 15.)

  6. The advantages of tall stack release of sulfur dioxide to reduce ground level

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concentrations do not apply for nitric oxide. Tall stacks potentially reduce ground level nitric oxide concentrations. However, nitric oxide converts to nitric acid and nitrates faster than sulfur dioxide converts to sulfuric acid and sulfates; and since the reaction products precipitate, there is a greater potential for local impact. (See Chapter 15.)

  1. There is considerable uncertainty about the effects of nitrogen oxide release from tall stacks on the formation of photochemical oxidants and on the ground level concentrations of oxidants and nitrogen dioxide. (See Chapter 15.)

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National Primary and Secondary Ambient Air Quality Standards

Pollutant

Type of standard

Averaging time

Frequency parameter

Concentration

µg/m3

ppm

Carbon monoxide

Primary and secondary

1 hr

Annual maximuma

40,000

35

8 hr

Annual maximum

10,000

9

Hydrocarbons (nonmethane)

Primary and secondary

3 hr

(6 to 9 a.m.)

Annual maximum

160b

0.24b

Nitrogen dioxide

Primary and secondary

1 yr

Arithmetic mean

100

0.05

Photochemical oxidants

Primary and secondary

1 hr

Annual maximum

160

0.08

Particulate matter

Primary

24 hr

Annual maximum

260

24 hr

Annual geometric mean

75

 

Secondary

24 hr

Annual maximum

150

24 hr

Annual geometric mean

60c

Sulfur dioxide

Primary

24 hr

Annual maximum

365

0.14

1 yr

Arithmetic mean

80

0.03

 

Secondary

3 hr

Annual maximum

1,300

0.5

aNot to be exceeded more than once per year.

bAs a guide in devising implementation plans for achieving oxidant standards.

cAs a guide to be used in assessing implementation plans for achieving the annual maximum 24-hour standard.

Source: EPA Regulations 40 CFR 50; and Commerce Clearing House, Inc. Pollution Control Guide 1974.

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New Source Standards of Performance for Fossil Fuel-Fired Steam Generators

Pollutant

Standard

Particulate matter

0.10 lb. per million BTU heat input, maximum two hour average

 

20 percent opacity (except that 40 percent opacity is permissible for not more than two minutes in any hour)

Sulfur dioxide

0.80 lb. per million BTU heat input, maximum two hour average when liquid fossil fuel is burned

 

1.2 lbs. per million BTU heat input, maximum two hour average when solid fuel is burned

Nitrogen oxides

0.20 lb. per million BTU heat input, maximum two hour average, expressed as NO2, when gaseous fossil fuel is burned

 

0.30 lb. per million BTU heat input, maximum two hour average, expressed as NO2, when liquid fossil fuel is burned

0.70 lb. per million BTU heat input, maximum two hour average, expressed as NO2, when solid fossil fuel (except lignite) is burned

 

Source: EPA Regulations 40 CFR 60.42 to 40 CFR 60.44

Suggested Citation:"Front Matter." National Research Council. 1975. Air Quality and Stationary Source Emission Control. Washington, DC: The National Academies Press. doi: 10.17226/10840.
×

PART ONE
HEALTH AND ECOLOGICAL EFFECTS OF SULFUR DIOXIDE AND SULFATES

Part One was prepared under the direction of the Assembly of Life Sciences of the National Research Council. Chapters 1 through 4 were written by Dr. Bernard Goldstein of the New York University Medical School. Chapter 5 is the work of Ian C.T.Nisbet of the Massachusetts Audubon Society. We are also indebted to the anonymous scientific reviewers who have contributed materially to the final form of Part One.

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ASSEMBLY OF LIFE SCIENCES

Executive Committee

James D.Ebert, Chairman, Carnegie Institution of Washington

Robert W.Berliner, Yale University School of Medicine

Frederick H.Bormann, Yale University

Theodore H.Bullock, University of California, San Diego

Robert H.Burris, University of Wisconsin

Donald S.Frederickson (ex officio), National Academy of Sciences

George K.Hirst, Public Health Research Institute of the City of New York, Inc.

Henry S.Kaplan, Stanford University Medical Center

Donald Kennedy, Stanford University

George B.Koelle, University of Pennsylvania School of Medicine

Estella Leopold, U.S. Geological Survey, Denver

Paul A.Marks, College of Physicians and Surgeons, Columbia University

Maclyn McCarty, Rockefeller University

Ray D.Owen, California Institute of Technology

Elizabeth S.Russell, The Jackson Laboratory, Bar Harbor

Nevin S.Scrimshaw, Massachusetts Institute of Technology

Emil L.Smith, University of California School of Medicine, Los Angeles

George F.Sprague, University of Illinois, Urbana

Kenneth V.Thimann, University of California, Santa Cruz

H.Garrison Wilkes, University of Massachusetts-Boston

James B.Wyngaarden, Duke University Medical Center

Thomas J.Kennedy, Jr., Executive Director

John Redmond, Jr., Staff Officer

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