Click for next page ( R2


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page R1
Report by the COMMITTEE ON MDTOR VEHICLE EMISSIONS Division of Engineering, National Research Council in accordance with Section 202(c) of the Clean Air Ameodmcuts of 1970 and in partial fulfillment of Contract No. 68-01-0402 between THE ENVIRONMENTAL PROTECTION AGENCY THE NATIONAL ACADEMY OF SCIENCES National Academy of Sciences Washington, D. C. February 12, 1973

OCR for page R1
NOTTCE The study reported herein was undertaken under the aegis of the National Academy of Sciences and with.the express approval of the Governing Board of the National Research Council. Such approval indicated that the Board considered that the problem is of national significance; that eluci- dation and/or solution of the problem required scientific and technical competence and that the resources of the National Research Council were particularly suitable to the conduct of the project. The members of the committee were selected for their individual scholarly and technical competence and judgment with due consideration for the balance and breadth of disciplines. Responsibility for the detailed aspects of this report rests with the committee, to whom we express our sincere appreciat ion . Reports of our study committees are not submitted for approval to the Academy membership. The report was reviewed by a panel of Academy members according to procedures established and monitored by the Academy's Report Review Committee. Such reviews are intended to determine, inter alla, 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 was approved, by the President, only after completion of this review process.

OCR for page R1
lo CONTENTS SUMMARY AND CONCLUSIONS 1. INTRODUCTION 1.1 Past Work of the Committee on Motor Vehicle Emissions 1.2 Panels of Consultants Page 1 L 6 7 8 1.2.1 Testing, Inspection, and Maintenance 9 1.2.2 Emission-Control Systems 9 1.2.3 Alternate Power Sources 9 1. 2 .4 Manufacturing and Producibility 10 1.2 .5 Driveability 11 1.2 .6 Catalysts 11 1. 2 . 7 Emission Standards and Atmospheric Chemistry 12 1.3 Other Means of Obtaining Information 111E STANDARDS, CERTIFICATION AND TESTING 3. 13 15 2.1 Numerical Values of Standards 15 2.2 Procedures for Certification, CVS-CH Test 15 2.3 Production-Line Testing 17 2.4 Compliance after Sale, Warranty 20 POTENTIAL OF SPARK-IGNITION INTERNAL-COM13USTION ENGINES PASSING EMISSION CERTIFICATION FOR 1975 and 1976 22 3.1 Introduction 22 3.2 Current Status of 1975 Systeus 22 3.3 Engine Emissions for 1976 Systems 25 3.3 .1 Introduction 25 3.3.2 Cold-Start Emission Controls 26 3 .3.3 Carburetors 28 3 .3 .4 Electronic Fuel Inj action 28 3.3.5 Exhaust-Gas Recycle (EGR) 29 3.3.6 Potential for Engine Emission Reduction 30 3.4 3.5 3.6 Feedback Control for Air-Fuel Ratio 3.7 Thermal Reactors 3.S Wankel Engine Catalysts Three-Way Catalysts 32 43 44 48 50

OCR for page R1
CONTENT S (Cons inued ~ Page 3.9 Stratified-Charge Engines 52 3. 9.1 Fuel-Injected Stratified-Charge Engines 3.9.2 Carbureted Stratified-Charge Engine 3.10 Effect of Emission-Control Devices on Vehicle Performance, Driveability, Fuel Economy, and Safety 3.11 Alternative Fuels 3.11. 1 Liquefied Natural Gas and Liquefied Petroleum Gas 3.11. 2 Status of Liquefied-Gas Substitutes for Gasoline 3.11.3 Hydrogen 3.11.4 Alcohols POTENTIAL OF SPARK-IGNITION INTERNAL-COMBIISTION ENGINES FOR MEETING STANDARDS IN USE 4.1 Introduction 4.2 Differences between Certification Test and In-Use Operation 4.3 Maintenance Procedures Required for 1975-76 Systems 4.4 Adequacy of the Service Industry 55 57 62 65 65 66 66 68 69 69 69 71 74 4.4.1 Training 74 4.4.2 Number of Mechanics 75 4.4.3 Equipment 76 4,5 State Action 76 4.5.1 Inspection and Maintenance Systems 76 4.5.2 Diagnostic Tests at Garages 81 4.5.3 Selection of Repair/Adjustment Standards 81 4.5.4 Timing and Cost of Inspection Facilities 82 4.6 Incorporation of Maintenance Considerations in Emission-Control System Design 4.7 Seminary 84 85

OCR for page R1
~~ I-` I.. CONTENTS (Cons inued ~ 5 . MANU;FACTVRING , COSTS, AND PRODUCIBILITY P. age 87 5.1 Manufacturability of Several Proposed Engine Systems 87 5.1. 1 The Dual-Catalyst System 87 5 .1.2 Diesel Engine 89 5 . 1.3 Wankel Engine 96 5 . l.4 The Carbureted Three-Valve Stratified- Charge Engine 97 5.1.5 A Typical Feedback-Controlled System 97 5.2 Manufacturability and Costs of Automotive Exhaus t Catalys ts 5 .3 Summary of Costs of Various Proposed Systems 5.4 Exercise to Illustrate the Impact of Possible Use of a Mix of Engines and Control Systems ALTERNATIVE SYSTEMS FOR LOW-E:MISSION AUTOMOBILES 98 100 102 104 6.1 Diesel Engines 104 6 . 2 Gas Turbines 105 6 . 3 S tilling Engi nes 107 6 .4 Electrically Driven Vehicles 108 6.5 Rankine Engines 110 6.6 Other Engines 112 7. DISCUSSION 113 7.1 Introduce on 113 7.2 Dual -Catalyst System 114 7.3 Alternatives to the Dual-Catalyst Approach 116 7.3.1 Carbureted Three-Valve Stratified-Charge Engine 1 16 7 .3.2 Diesel Engines 117 7 . 3 . 3 Wankel Engines 117 7.3.4 Catalytic Systems with Feedback Control 118 7 .4 Interim S tandards 7.5 Effects of a Delay in Enforcement on Total Automobile Emissions 7.6 Implementation of 1975 and 1976 Standards and Related Matters 118 119 124

OCR for page R1
- APPENDIXES A. Co~'ittee on Motor Vehicle Emissions Page 128 B. Panels of Consultants 130 C. Persons, Groups, and Companies from whom the Committee Obtained or Sought Information 132 D. Announcements placed in Federal Register requesting information with respect to technological feasibility TABLES 3-1 Emissions Performance of Major Manufacturers 1975 Model Year Development Fleets 140 24 3-2 Engine Emissions at Low Mileage: Mean and Standard Deviation 3 3-3 Examples of Best Low Mileage Emissions Measurements with Dual-Catalyst Systems on Experimental 1976 Vehicles Emissions As Function of Mileage for Durability Tests on Dual-Catalyst Systems 3-5 Low-Mileage Emissions from Compact and European Vehicles Equipped with Three-Way Catalyst System 3-6 Effect of EGR on Wankel Bare Engine NOX Emissions 3-7 Best Emissions Results, Thermal Reactor and Wankel Engine 2750-lb Compact Car 3-S Emissions at Low Mileage, Rotary Engine with Oxidation Catalyst 3-9 Emissions from Military Jeep with Strati fled-Charge Engine 35 39 47 51 53 54 56

OCR for page R1
in. ~ TABLES (Continued ~ Low-Mileage Emission Levels for PROCO Conversion 3-11 Low-Mileage Emissions Data from Honda Tests of CVCC Systems 3-12 Durability Data fray Honda Tests of CVCC System Chronology of Development of the Dual-Catalyst Sys ten Estimates of Sticker Prices for Emissions Hardware from 1966 Uncontrolled Vehicle to 1976 Dual- Catalyst System 5-3 Summary of Sticker Prices for Emissions Hardware from 1966 Uncontrolled Vehicle to 1976 Dual- Catalyst System 5-4 Total Annual Cost to Customer of Emission Controls For Various Body and Engine Combinations FIGURES Page 58 60 61 88 90 94 101 3.1 Typical Dual-Catalyst System 33 7.1 Emissions of Hydrocarbons by Automobiles in Urban Areas 7.2 Emissions of Carbon Monoxide by Automobiles in Urban Areas 7.3 Emissions of Oxides of Nitrogen by Automobiles in Urban Areas 121 122 123 _>

OCR for page R1

OCR for page R1
- ~ NATIONAL ACADEMY 0F SCIENCES OFFICE OF THE PRESIDENT 2101 CONSTITUTION AVENUE WASHINGTON, D. C. 20418 The President of the Senate The Speaker of the House of Representatives The Administrator of the Environmental Protection Agency Sirs: February 15, 1973 I have the honor to transmit a report summarizing the work and findings. of our.Committee an Motor Vehicle Emissions in accord with the provisions of Section 6 of Public Law 91-604, the Clean Air Amendments of 1970. We.trust.that this report will.b.e of assistance to the Administrator of the Fnvironmenta1 Protection Agency in discharging his responsibilities finder that Act and that it will inform the Congress of the progress which has been made, to date, toward achieving some of the goals of that Act. . . The report constitutes a description, as of 1 February, of the "technological feasibility," on the part of the automobile and related industries, of achieving the automotive emissions control standards established by. the Act. As the.report reveals, that Act has stimulated an almost worldwide effort to develop effective emissions ~ ~ ~~ ~ report is presented at a tome when the pace or developments can readily overtake categorical conclusions based on the inf ormation available today; it is, therefore, a review of the current "state- of-the-art," presented while that state is changing rapidly, and not a summary of a stabilized situation. It is for that reason, inter alla, that the report presents an analysis but offers no recommendations concerning enf orcement, on schedule, of the rele- vant provisions of the Act. control systems. Of necessity. however this _ , , The Committee defined "technological feasibility'' to mean that an emissions control system capable of meeting the standards set for the three major.pollutants can be developed, designed, produced in large numbers, and maintained in service, all at reasonable cost. By these criteria, the Committee's analysis indicates that achievement of the 1975 standards may be techno- logically feasible and that achievement of the 1976 standards is likely but may not be attainable on the established schedule. However, these seemingly definitive conclusions are offered with several reservations which are held in varying degrees of

OCR for page R1
2 gravity by individual members of the Committee. The nature of these reservations will be found in the report. They are con- cerned, variously, with the durability in customer use of catalyst- dependent control systems, the requirement for a network of inspec- tion and maintenance stations, the actual likelihood of sufficiently early development of a dual-catalyst system capable of achieving the 1976 standards, and the likelihood of manufacture for Model Year 1976, on a scale commensurate with projected total national production, of a sufficient number of vehicles actually capable of meeting the 1976 standards in customer use. The Committee is seriously concerned that the certification procedure may not prove to be an adequate indicator of the continu- ing reliability of catalyst-dependent, emissions control systems under the more stressful, varied conditions of consumer use. Data in this regard are not yet available, even for systems intended to meet the 1975 standards. To assure that vehicle classes certified for production actually do continue to meet the prescribed standards, the Committee considers it advisable to develop a network of inspection and maintenance stations and to train a corps of mechanics sufficient to that task. Some of the Committee, however, suggest that no more need be done than to enforce the recall provision of the Act, when so indicated by defective behavior of a reasonable sample of vehicles. It should be noted, however, that whereas that provision is binding upon the manufacturer, it is not mandatory for the vehicle owner to respond. In view of the low response to recalls for defects relating to passenger safety (30 to 507), simple use of the recall provision under these circumstances would not suffice to meet the goals of the Act. In this regard also, it should be noted that there is not available, for such national use, a relatively simple, foolproof, reliable, diagnostic instrument for assessment of the automotive emission of the three pollutants with which the Act is concerned. It may be necessary f or the Environmental Protection Agency to stimulate the research and development required to make such instrumentation available on the schedule necessitated by the Act. The Committee found it unnecessary and inadvisable to recommend a set of interim standards for 1975 or 1976 model year vehicles. But, while contemplating its responsibility for such a recommenda- tion, under the terms of the contract, the Committee became aware of controversies surrounding many aspects of the problem of stan- dard setting, e.g., the nature and magnitude of the hazards to health posed by the pollutants released in automotive emissions, the relationships among the various pollutants and their ambient concentrations with respect to their health effects, the relative contributions of mobile and stationary power sources, etc. Resolution of these controversies appears imperative to long-term policy with respect to the protection of air quality. Hence, on page 127, the Committee urges that Congress and the Environmental !

OCR for page R1
3 Protection Agency initiate a comprehensive study of these and related matters. This Academy would be pleased to be of assistance in such an effort. That recommendation should not be interpreted as taking exception to the standards established by the Clean Air Act of 1970. Most of the Committee believes that only if such an examination were to reveal compelling evidence and arguments to the contrary should the effort to achieve the emissions control standards established by the Act be relaxed; indeed, the Committee is particularly concerned that continued progress be made with respect to improvement of air quality in those urban centers where, patently, automotive emissions have contributed significantly to the deterioration of the local environment. A major quandary which the Committee wishes to place before the Congress and the Environmental Protection Agency (page 5) arises from awareness of the relatively recent development, largely in the hands of a Japanese manufacturer, of a dual-carbureted, stratified charge engine. Although the general principle is not new, the particular design in question, incorporated into small size engines, has met the 1975 certification standards and bids fair to meet the 1976 standards. As compared with the catalyst-dependent systems now being emphasized by the major manufacturers this system offers the promise of lower initial purchase costs, greater dura- bility in service and significantly greater fuel economy. The Committee is concerned that mass production of what are presently deemed to be relatively fragile, catalyst-dependent systems, of unproved reliability In actual service, may engender an episode of considerable national turmoil. It is further concerned that, once committed to the manufacture of catalyst-dependent control systems, rather than switch to some more generally acceptable system such as a version of the stratified charge engine that now offers great promise, the relatively ponderous automobile industry will continue to manufacture catalyst-dependent systems for some years, albeit, presumably, while also seeking more durable catalysts and mechanisms to reduce the severe fuel penalty of current catalyst-dependent systems with their associated mechanical features. The dilemma, then, is to determine what course of action, by government, would assure the earliest possible optimal outcome while scrupulously avoiding dictation, by government, of the technology to be used. The Committee offers no recommendations in this regard. Relevant to this situation are the costs, per vehicle, asso- ciated with the initial purchase, maintenance and operation (including the effects on fuel consumption) of the various emissions control systems under consideration. The annualized incremental costs, viz., the cost per car/year for a standard engine, relative to a 1970 standard engine, due to the emission control system, for operation and maintenance of the vehicle with the purchase cost of the system amortized over the first five years of operation, were

OCR for page R1
i '^ ) found, by the Committee to be as follows: 1973 engine, about $100; single catalyst system (1975 standards), about $225; dual catalyst system (1976 standards), about $270; and the dual-carbureted stratified charge engine, about $70. The high annualized costs of the catalyst systems reflect the serious associated fuel penalties. For the nation, these costs represent a concrete example of the principle that the costs of environmental protection can be met only if they are internalized. The magnitude of this process derives from the great numbers involved, viz., about 107 (10 million) vehicles produced per year and almost 108 (100 million) registered automobiles. Thus, a one-year production of 107 vehicles equipped with the presently proposed dual-catalyst system would result in additional expenditures -- as compared with 1970 automobiles -- of $2.7 billion per year for each of the first five years of the life of that model year of cars, assuming constant fuel prices, and about $2 billion per year thereafter. In due course, all vehicles will be equipped with emission controls capable of meeting the 1976 standards. There all (108) cars equipped with the dual-catalyst system, at current costs this would result in a national annual total expenditure for emissions control of the order of $23.5 billion (assuming a mean life of ten years/car with purchase cost amortized over the first five years, and current fuel prices). Such figures are to be taken as no more than an indication of their orders of magnitude. The increased sticker price would tend to cause consumers to buy smaller cars of greater fuel economy and the fuel penalty would tend to reduce mileage. The initial costs will probably decline as dual-catalyst systems and their manufacture are improved. On the other hand these gains could be offset by the foreseeable rise in fuel prices. Unless satisfactory feedback control and fuel injection systems, for catalyst-dependent systems with the associated mechanical features, become available, the total costs will be dominated by the fuel penalty associated with such systems. These costs, in dollars and in depletion of fuel reserves, are so great that they should serve as a national incentive to hasten the development of reliable lower-cost alternatives to the dual-catalyst system as a solution to the problem of emissions control. In contrast, several of the promising alternatives, such as the carbureted stratified-charge engine, carry with them costs of the order of those already associated with the 1973 engine, viz., an annualized cost for emissions control of about $100/car during the first five years of service, for an annualized total of perhaps $7.5 billion for the full fleet of 108 cars.

OCR for page R1
- s - Costs of these magnitudes suggest, of themselves, the need for attention to a series of considerations which lie outside the scope of the present report. Among such questions are: What is the effect of this enterprise on the GNP? Is it, in effect, a stimulus to the overall economy or are the funds utilized to defray these expenditures removed from alternate uses in the economy, em., for improvement in the health care delivery system? If the answer to the latter is affirmative in significant measure, is this the wisest use of such funds for protection of the public health? What effects would large-scale employment of the most promising emissions control systems have on the international balance of payments? If emissions control can only be satisfactorily accomplished by acceptance or' a large fuel penalty, e.g., the dual-catalyst system or the Wankel engine with thermal reactor, what judgment should be made under such circumstances? Should it turn out that noble metal catalysts are more effective and, seemingly, economic than other catalysts, how should one weigh this raid on the very limited supply of this resource in the skin of the planet ? Whereas pollutant emission is undesirable anywhere, emission control does not appear, today, to be essential on the basis of either essentially aesthetic or health considerations in large areas of the nation. Indeed, overall, natural production of hydrocarbons, carbon monoxide and perhaps NOx far exceeds that from man-made sources. In view of the costs to the nation, in dollars and in fuel consumption, of early implementation of the 1975-76 standards, atten- tion seems warranted to the possibility of temporarily enforcing the established emissions standards only in those specific urban areas where air quality is known to be adversely affected by auto- motive emissions, reserving national implementation for the day when there are available reliable, relatively inexpensive emissions control systems which exact no fuel penalty. Emissions control is but one aspect of "the problem of the automobile" in our society. This device has given Americans an 'automobility' unknown in previous human history, enriched the personal experience of each of us, broadened our horizons and helped to make the large expanse of American geography into one nation. But this aspect of our society has begun to be defeated by its very success. The automobile has also accelerated depletion of several criti- cal natural resources, including the petroleum which fuels it. It has scarred the land and choked the city, contributing seriously to deterioration of the quality of urban life . In the long run, the truly effective mechanisms for emission control must include a significant reduction in the number of cars operated in the city, a solution dependent upon acceptable, public mass transit systems, and a substantial reduction in the mean size (weight, volume, and !

OCR for page R1
i-% ~ at- i 6 horsepower) of those automobiles which do function in the city, as well as , perhaps, redistribution of the pattern of physical relation- ships among dwelling and working.areas. Patently, these are relatively long-term goals, achievement of which will require extensive, meticulous study and planning with subsequent large public expenditures and careful public intervention into the behav- ior of the private sector. For the short term, however, automotive emissions control can be accomplished by a relatively simpler, technological "quick fix," and, perhaps, on the schedule established by the Clean Air Amend- ments of 1970. The attached report summarizes the status of the alternatives currently offered as means whereby to achieve the earliest acceptable technological solution to.this problem. Respectfully yours, Ph ip Handler President !

OCR for page R1
NATIONAL RESEARCH COUNCIL NATIONAL ACADEMY OF SCIENCES NATIONAL ACADEMY OF ENGINEERING SI01 CONS~U=ON AVEN" WASHINGTON, D.C. so4~8 COMMITTEE ON MOTOR VE}lICLE EMISSIONS OF THE DIVISION OF ENGINEERING Dr. Philip Handler President National Academy of Sciences 2101 Constitution Avenue, N.W Washington, D . C. 20418 Dear President Handler February 12, 1973 . . I am herewith transmitting for submission by the Academy to the Congress and to the Environmental Protection Agency the Report of the Committee on Motor Vehicle Emissions dated February 12, 1973 Sincerely your 2~: E. L. Ginzton ~ Chairman J TELEPHONE: 202 -96 ~ - ~ 62 ~

OCR for page R1