SUTIARY /Yin AMALYSIS OF COfTfNTS
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NOTICE OF PROPOSE) RIJIP1AKIM
FOR THE
COMTROL OF LIGHT-DUTY DIESEL PARTIOJLATE B-11SSIOMS
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OCTOBER 3579
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Summary and Analysis of Cotmnents
on the
Notice of Proposed Rulemaking for the Control of
Light—Duty Diesel Particulate Emissions
from 1981 and Later Model Year Vehicles
October 1979
Standards Development and Support Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Office of Air, Noise and Radiation
U.S. Environmental Protection Agency
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S umina r y
On February 1, 1979, EPA proposed an emission standard
for particulate emissions from diesel—powered light—duty vehicles
and diesel—powered light—duty trucks. The proposed particulate
standard was 0.60 g/mi (0.37 g/km) beginning in 1981 to be reduced
to 0.20 g/mi (0.12 glkm) in 1983. A public hearing was held on
March 19—20, 1979 for interested parties to comment on the proposed
emission standards. Parties that made presentations at the hear-
ing are listed in Table S—i. A period of thirty days after the
public hearing was provided for written comments to be submitted to
EPA. This period ended April 19, 1979. Twenty—eight written
submittals were received, and these are also shown in Table S—i.
The comments addressed seven main areas: environmental impact,
control technology, leadtime, level of the standards, economic
impact, alternative regulatory approaches, and test procedures.
EPA has examined and analyzed these comments and a summary of the
comments and EPA’s recommendations immediately follows. Detailed
analyses of the comments can be found in sections I to VIII of this
report.
Environmental Impact
The comments discussed in this section generally addressed
EPA’s assessment of the need for this regulation. Chrysler
and Congressman Dingell challenged that the proposed regula-
tion was not based on any proven adverse health effects. This is
not the case as there is a wealth of evidence of health effects
associated with suspended particulate, much of which is discussed
in Chapters 7 and 9 of a National Academy of Sciences report
entitled “Airborne Particles”. The Department of Energy (DOE)
suggested that EPA should emphasize the fine particulate fraction
of particulate emission on health effects, while Ford and Dr.
Farkus of the University of Waterloo asked EPA to include data to
show that diesel particulate has unusual toxic properties with
respect to typical suspended particulate. These requests are well
taken and a section should be devoted to these topics in the
Regulatory Analysis. Ford also claimed that EPA must base its
emission standard on some property of diesel particulate, other
than mass, which related more to the health effect of the partic-
ulate and that this could only be done after a more complete
assessment of diesel health effects had been made. EPA rejected
this argument as Congress did not allow time for such an assessment
before requiring emission standards and the precedent of using mass
as a general indicator of hazard has long existed with the ambient
air quality standard for particulate matter.
The Council of Wage and Price Stability (CWPS) and Congressman
Kildee claimed EPA did not demonstrate that Kansas City was
representative of the rest of the nation nor did EPA compare the
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Table S—i
Cotraiienters and Speakers for Proposed Emission
Regulations for Light—Duty Diesel Particulate
NPRM Commenters for Proposed Light—Duty
Diesel Particulate Regulations
Speakers at Public Hearing
on March 19—20, 1979
1. U.S. Metric Board
2. Dr. Farkus of the University
of Waterloo
3. BMW
4. Imperial Chemical Industries,
Limited
5. American Motors Corporation
6. Fiat
7. Daimler—Benz
8. Ford Motor Company
9. International Harvester Corp.
10. General Motors Corporation
11. Volvo
12. F. Black, ORD, EPA
13. Chrysler Corporation
14. Council on Wage and Price
Stability
15. Department of Commerce
16. Ricardo
17. Toyota
18. Peugeot—U.S. Technical Research
19. East Michigan Environmental
Action Council
20. Hogan and Hartson
21. P.S.A. Peugeot—Citroen
22. Natural Resources Defense
Council
23. Volkswagen of America
24. Congressman Dingell
25. Environmental Protection
Agency Lab Branch
26. Department of Energy
27. Diesel Auto Association
1. Congressman Dale E. Kildee
2. Congressman Robert Carr
3. Dr. Ancker—Johnson of
General Motors Corporation
4. Congressman Andrew Maguire
5. Mr. Misch of Ford Motor
Company
6. Mr. Engel of Chrysler Corp.
7. Dr. Negro of Fiat Motor Co.
8. Mr. Cornetti of Fiat Motor
Company
9. Mr. Buttgereit of Volkswagen
of America
10. Mr. Van Winsen of Daimler—Benz
11. Jean Perez of Automobile
Peugeot
12. Mr. Balgord of Environmental
and Natural Resources Technol-
ogy
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relative diesel impact in Kansas City to that across the nation.
This comment is also well taken and estimates of the diesel’s
impact in New York, Chicago, Los Angeles, and other cities should
be made to insure that the impact determined is indeed a nationwide
impact. CWPS and DOE also stated that the traffic growth rate was
overestimated for a central city area. This is confirmed by
traffic growth rates used in past CO modelling done by EPA so a 1%
per year increase in VMT should be used in the studies of Kansas
City and other cities, as opposed to the 1.5% growth rate original-
ly used.
General Motors, DOE, and Congressman Kildee challenged EPA’s
sales projections believing them to be unrealistic. Based on
additional information provided by the automobile companies and
revised EPA estimates, the original sales scenario does seem to
overestimate diesel sales prior to 1988. A revised scenario,based
on the information submitted to EPA, has been assembled which
results in a 17% decrease from the original estimate of light—duty
diesel travel in 1990 and which is a much better estimate for
diesel sales in the early 1980’s.
Ford, DOE, and CWPS thought that EPA’s estimate of the road-
side impact of diesels was unrepresentative and overestimated. A
closer examination of the origin of the correlation used to esti-
mate this impact confirmed that an overestimation was made. This
aspect of the Regulatory Analysis should be revised and the local-
ized impacts will be placed in a more appropriate perspective with
respect to time of exposure, extent of population exposed, etc.
DOE made the objection that the population exposure was based on
many questionable assumptions and extrapolations, and that it
should be improved or deleted. Questionable assumptions and
extrapolations contained in the population exposure analysis were
found and some would require considerable effort to improve or
defend. As this analysis is not crucial to the environmental
analysis, it seems best to delete the population exposure analysis
at this time and leave it to be improved and defended at a later
date when its need is more pressing.
Control Technology
The comments discussed in this section address the ability of
technology to reduce particulate emissions from diesels. Fiat,
Peugeot, GM, Ricardo, DOE and Daimler—Benz (D—B) all commented on
the ability of engine modifications to reduce particulate emissions
with all except Peugeot believing that further reductions were
possible. An analysis of these conmients and the available data
confirmed EPA’s original position that potential reductions were
and are still available from engine modifications. Ricardo, D—B,
GM, Ford, and DOE all challenged EPA ’s position that turbocharging
could reduce particulate emissions by one—third, while Peugeot and
Fiat stated that turbocharging could reduce particulate emissions
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but would do so to a lesser extent or would require more time for
implementation. From the available data, it appears that turbo—
charging is not a quick and easy technique for reducing particulate
emissions. However, it appears that a concerted effort to turbo—
charge a diesel can reduce particulate emissions 20—30%.
There are considerable problems involved with utilizing
catalyst technology to reduce particulate emissions. This is
evident from comments by Ricardo, Fiat, BMW, GM, and Ford. Unless
a technological breakthrough occurs, conventional catalytic con-
verters are not likely to be used on diesels for particulate
control. Ricardo, fl—B, and GM all commented on the use of simple
traps for reducing particulate emission. Although traps are
efficient control devices over short distances (less than 1000
miles), they must be replaced or regenerated externally. Besides
the technical problems with external regeneration, there are
serious questions concerning the public’s willingness and ability
to service traps every 1000 miles. Because of this, traps do not
appear promising at this time. Trap—oxidizers, which are traps
which regenerate automatically on board, appear very promising,
even though GM, D—B, Ford, and Imperial Chemical Industries
Limited expressed concerns about the ability of trap—oxidizers
to reduce particulate emissions without possible backpressure
effects. Research is still needed to develop the optimum trapping
material and improve the oxidation control, but given enough time
these problems do not appear insurmountable and approximately a
two—thirds reduction should be achievable by these devices.
D—B and GM suggested that fuel modifications appear to have
some potential to reduce particulate emissions, but there are
significant problems yet to be overcome. Fuel additives can
cause a decrease in particulate emissions, but usually increase the
emission of other pollutants, such as the additive itself (e.g.,
barium). Research on the effect of fuel composition on particulate
and other emissions is still in an early stage and EPA will con-
tinue to stay abreast in this area. Finally, Ford did present data
for their PROCO engine, showing its fuel economy to be as high as
that of a diesel while producing lower particulate and NOx emis-
sions. However, there are other problems with this engine which
must be solved before it can be considered viable for production
purposes.
Leadt ime
The continents in this area primarily dealt with the time needed
for various control techniques to be implemented on production
vehicles. The three types of control technology addressed were
engine modifications, turbochargers, and trap—oxidizers. Both D—B
and DOE stated that the time remaining before the 1981 model year
would not allow enough time for the introduction of any new engine
modifications. This does appear to be the case. However, some
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engine modifications have already been developed and planned for
introduction in 1980—81 which reduce particulate emissions and can
be expected to be in place by 1981. GM and Volkswagen (VW) both
commented that they could not turbocharge their engines before
1983 and 1982, respectively. It appears that widespread use of
turbocharging cannot be expected until the 1983 model year, though
some manufacturers who have been working in this area longer may
have turbocharged engines available sooner. Both GM and VW stated
that trap—oxidizers would not be available for the 1983 model year,
but might be available for the 1985 model year. An analysis of the
available information indicates that trap—oxidizers indeed will not
be available in time for the 1983 model year, but should be avail-
able for the 1984 model year.
Level of Standards
This section includes conmients regarding the proposed level of
standards for light—duty diesel particulate emissions. The pro-
posed standards were 0.6 5/mi (0.37 g/krn) for 1981 to be reduced to
0.2 g/mi (0.12 g/km) for 1983, and were based on the lowest partic-
ulate levels achievable by the worst light—duty diesel with respect
to particulate emissions. Chrysler challenged EPA’s basis for
proposing this standard, believing the standard should be 1.02 g/mi
(0.63 g/km) or greater, arguing that the 1981 standard should be
set at the highest particulate level EPA found in its baseline
testing of 1979 certification diesel vehicles. However, Chrysler’s
argument is in conflict with the letter and spirit of the Clean Air
Act, and does not weaken EPA’s basis for the proposed standard.
CWPS claimed that the proposed standard would be overly “technology
forcing,” while the Natural Resources Defense Council and Congress—
man Andrew Maguire stated that the standards should be set with
an emphasis on the impact on public health. The Council’s claim
that technology is being forced too hard or too quickly cannot be
accepted, as the technology is expected to be available in the time
frame required (see Control Technology section). With respect to
the latter commenters, this proposed standard should be protective
of the environment and public health, but available technology is a
limiting factor, as outlined in the Clean Air Act. Comments from
Fiat, Ford, GM, and Congressman Kildee pointed out that current NOx
control techniques cause particulate emission to increase. These
comments are well taken and the particulate standard that is
promulgated is based on a NOx waiver level of 1.5 5/mi (0.93 g/km)
as opposed to the statutory NOx standard of 1.0 g/mi (0.62 g/1 n)
for 1981.
Peugeot and GM each stated that a deterioration factor,
ranging from 1.1 to 1.7, was necessary to account for durability
considerations. An analysis of all the available data shows that
the deterioration factor for particulate emissions should be very
close to unity (1.0—1.1) and not 1.1—1.7. Peugeot, GM, and Volks-
wagen expressed concern that EPA had not accounted for car—to—car
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emission variability in determining the proposed standards.
However, the statistical sampling program of the Selective Enforce-
ment Auditing (SEA) program already accommodates vehicle—to—vehicle
emission variability, so this factor was indeed accounted for.
Concerning the reasonableness of the proposed standards,
Peugeot, CWPS, D—B,and Fiat all stated that the 0.6 g/tni (0.37
g/Icn) particulate standard for 1981 could he achievable by relaxing
the NOx standard to 1.5 g/mi (0.93 g/km). Volkswagen believed that
the 0.6 g/mi (0.37 g/km) particulate standard should be delayed to
1982, with a NOx waiver at 1.5 g/mi (0.93 g/kin). GM, Ford and
Chrysler claimed that the standard should be set at 1.0 g/mi (0.62
g/km) for 1981. As discussed thoroughly in the Control Technology
section, the 0.6 g/tni (0.37 g/km) standard can be met with some
engine modifications, with a NOx standard of 1.5 g/mi (0.93 g/kin)
or less. DOE, Volkswagen, Peugeot, Toyota, Department of Commerce,
CWPS, Volvo, GM, and D—B were skeptical of meeting a particulate
emission standard of 0.2 g/mi (0.12 g/km) beginning with the 1983
model year. EPA acknowledges that 1983 would be too early for all
vehicles to meet that standard, and the 0.2 g/mi (0.12 g/km)
standard should be deferred until 1984 (see also Leadtime sec-
tion). The Natural Resources Defense Council was the only corn—
menter to claim that a tighter standard could be met for 1983. We
find no technical support for this position.
GM, International Harvester, D—B, Chrysler, and CWPS all
commented that a higher standard should be proposed for light—
duty trucks (LDTs). An analysis of the available data shows that
particulate emissions increase 16—18% for a vehicle inertia weight
increase of 1000 pounds. Flowever,a 2.3 g/ini (1.43 g/krn) NOx
standard for LDT’s is much less stringent than even the LDV NOx
waiver level of 1.5 g/mi and should allow LDT manufacturers to meet
a 0.6 g/mi (0.37 g/km) particulate standard in 1981. By 1985, the
NOx standard for LDT’s will be as stringent as the LDV standard and
the inertia weight effect should be taken into account. Thus, a
30% increase in the emission standard has been allowed LDT’s, to
0.26 g/mi (O.16g/km), beginning in 1984.
Some environmental groups suggested a more stringent standard
for 1990. This is a possibility. A more stringent particulate
standard in the future will have to be justified by health effects
research showing diesel particulate to be a greater health threat
than just as a contributor to total suspended particulate, and by a
finding that the more stringent standard is technologically
feasible.
Economic Impact
This section includes comments concerning the costs, economic
methods, and cost—effectiveness of particulate control for light—
duty diesels. A major item of concern was the cost of the trap—
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oxidizer system. BMW, Chrysler, and GM all stated that the
cost of the trap—oxidizer system was underestimated. EPA per-
formed a detailed analysis of the costs of all the components in a
trap—oxidizer system and increased its original estimate of $114—
$157 per vehicle (in 1979 dollars) to a fleetwide average of
$189—224 per vehicle in 1984, which should reduce to $128—$152 per
vehicle in 1988. This revised estimate was primarily based on
component costs taken from a study by Leroy H. Lindgren (Rath and
Strong), “Cost Estimation for Emission Control Related Components!
Systems and Cost Methodolgy Description.” Chrysler also claimed
that the trap—oxidizer would require maintenance during the vehi-
cle’s life, while CWPS claimed that the trap—oxidizer would have to
be replaced once during the life of the vehicle. EPA found Chry-
sLer’s claim to be reasonable and estimated this maintenence to
cost about $30, occuring once after about five years of vehicle
operation. The Council’s claim was not accepted, however, since
the trap—oxidizer is expected to be made of durable material, such
as stainless steel, and last the life of a vehicle, as do current
catalysts. However, EPA also found that use of the trap—oxidizer
should reduce normal maintenance costs by $80, leaving a net
savings of $50 due to use of trap—oxidizers.
Chrysler, D—B, Fiat, GM, Volkswagen, Ford, DOE, and the
Department of Coimnerce criticized EPA for underestimating the cost
of turbocharging and overestimating the fuel economy improvement of
turbocharging. The original costs of turbocharging, between
$145—$185, were reassessed and should be revised to $207—$238 due
to the need for additional engine modifications which are necessary
for the engine to be optimized with the turbocharger. A second
analysis of the available data still shows that turbocharging
should increase fuel economy by 8% and this estimate should not be
revised. The Department of Commerce and CWPS suggested that EPA’s
projection that fuel costs would increase 10% per year faster than
the general price index was too high. CWPS suggested that a 5%
rate was more reasonable and that discounting fuel costs by a 5%
rate (instead of 10%) would accomplish this. An analysis of price
increases over the last six years did show 5% to be the more
reasonable rate for long term considerations and should be used in
the future.
International Harvester (IHC) and GM each challenged the
original estimate of costs for test equipment and testing proce-
dure. IHC believed EPA’s regulation would add $270.10 per vehicle
in 1981—82, and $562.67 in 1983—85. IHC also requested that they
be allowed to assign deterioration factors rather than have to run
a durability vehicle. This is already allowed under existing rules
and this proposed regulation did not attempt to change these
rules. Omission of the cost of the durability vehicle substan-
tially decreases the overall cost to IHC, putting their costs in
line with other manufacturers. GM claimed that facility modifica-
tions would be five times higher than predicted by EPA. Although
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GM may actually intend to spend more than EPA has estimated for
each test site and test facility, much of the additional expense
seems to be for higher levels of automation which is discretionary,
and must pay for itself in the long run or else GM should not move
in that direction. EPA did reanalyze the potential costs of test
cell and facility modifications and has increased the cost of each
to $55,000 and $30,000, respectively.
CWPS stated that the marginal cost effectiveness of the
1983 standard appears to be too high when compared to other control
techniques. This comment can not be accepted without further
analysis, as cost effective figures expressed in simple dollars per
ton units may not allow an accurate comparison of different control
strategies to be made. A more appropriate measure of cost effec-
tiveness will be developed in the final Regulatory Analysis and the
CWPS data will be included. CWPS also suggested implementing
Street cleaning as an alternative economic control strategy to
diesel particulate regulations. EPA found this control strategy to
have minimal effect on regional air quality and even questionable
effect in highly localized areas (curbsides). Thus, EPA found it
to be an unacceptable alternative to light—duty diesel particulate
regulations.
Alternative Regulatory Approaches
Comments in this section concern alternative approaches to
controlling particulate emissions from light—duty diesels via a
smoke standard, a Corporate Average Particulate Standard (CAPS),
and a Diesel Average Particulate Standard (DAPS). American Motors
suggested a smoke standard to satisfy the Clean Air Act requirement
for the 1981 model year. The application of a smoke standard was
rejected because smoke opacity does not correlate well with
particulate emissions. Opacity is primarily a function of the
optical properties of particulate, and as such is appropriate only
for standards based on aesthetic considerations.
GM proposed the concept of a Corporate Average Particulate
Standard (CAPS), resulting in a sequence of particulate standards
based on the average level of particulate emissions of a manufac-
turer’s entire gasoline and diesel fleet. In addition to CM,
comments on this proposal were received from CWPS, Volvo, Ford,
DOE, Volkswagen, Peugeot, Associate Professor Edward J. Farkas,
Citizens for Clean Air, and the Natural Resource Defense Council.
Proponents considered the main advantage of CAPS to be the in-
creased flexibility a manufacturer would have in tolerating dif-
ferent levels of particulate emissions while meeting the CAPS
standards and without affecting overall air quality. CAPS also
puts an implicit ceiling on total light—duty diesel particulate
emissions to the atmosphere. Opponents said it would favor large
gasoline—powered vehicle manufacturers and would limit the fraction
of diesel vehicles that could be sold by manufacturers who sell
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primarily diesels. It would likely necessitate major changes in
existing enforcement procedures. Also, it would increase the
likelihood of a concentrated amount of high particulate vehicles
within a given region. GM ’s CAPS porposal will be evaluated by
weighing the aforementioned advantages and disadvantages.
The Diesel Average Particulate Standard (DAPS) is a proposal
by VW that is very similar to CAPS, with the exception that it
averages diesel vehicles only rather than gasoline and diesel
powered vehicles. In addition to Volkswagen, comments on the DAPS
proposal were received from CWPS, Peugeot, and Volvo. Volkswagen
pointed out that the main advantage of DAPS is that it does not
favor large gasoline—powered vehicle manufacturers. On the other
hand, DAPS does not limit the total light—duty diesel particulate
emissions loading to the atmosphere as CAPS does. Otherwise DAPS
shares many of the same advantages and disadvantages of CAPS.
EPA should continue to evaluate CAPS and DAPS as serious
alternatives to the individual vehicle standards. Should the
Agency decide to pursue an average standard, we agree with DOE that
a new rulemaking would be required to give interested parties
the opportunity to comment on the specific proposal.
Test Procedure
Comments in this section deal with the proposed test procedure
for measuring light—duty diesel particulate emissions. GM and
International Harvester commented that filter temperature specifi-
cations were unrealistic, causing some hydrocarbons to be counted
as both particulate and gaseous hydrocarbons. While some hydro-
carbons are indeed counted twice, it has not been proven that
hydrocarbons do not leave the particle while suspended in the
atmosphere. The stringency of the particulate standard is not
affected by this double—counting since the particulate baseline was
developed under the same conditions. GM, Ford, D—B, and Chrysler
have commented that the 125°F particulate sample zone temperature
is without technical foundation. Data now available support using
this temperature which was chosen to prevent a loss of hydrocarbons
by thermal desorption. Ford claimed that fluorocarbon—coated glass
fiber filters have difficulty achieving the originally required 98%
filter efficiency. This fact is acknowledged. A new filter
acceptance criteria, requiring the use of a back—up filter and the
inclusion of the particlate mass on this filter when the collection
efficiency of the first filter is less then 95%, is being recom-
mended.
GM recommended that the required particulate sample flow rate
provision be dropped. This comment was accepted; specified
filter flow rates will no longer be required. GM stated that
regulations should be changed to require a 1—hour filter stabi—
lization period after a vehicle test. This change is acceptable
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and the mini urn post—test stabilization period will be changed to
one hour eve: though a 0.5% increase in particulate may occur. GM
also requested that the specific requirement for a heat exchanger
(with the CFV sampler) should be replaced by a general requirement
for flow proportionality. This change in test procedure can not be
approved, as confirmatory data was not received showing the
equivalency of the alternative system. GM commented that the
tailpipe connecter specification is too rigid. This comment has
brought to attention the need to conduct more testing in the area
of tailpipe heat loss effects, which should be completed by the
time the Final Rule is promulgated. GM suggested the use of flow
measurement devices to replace gas meters, and that tolerance of
+2 percent on sample flow rate should replace the +5 percent
tolerance. It is agreed that gas meters are a burden and that flow
measurement devices should also be allowed. However, the +2
percent tolerance cannot be granted unless first proposed for
comment. GM comn1ented that commercially—available heated lines
cannot meet the proposed temperature specifications. However, GM ’s
own data verifies that the proposed temperature specifications can
be met. It appeared that GM failed to realize the distinction
between probe—wall temperature specifications and dilute exhaust
gas specification. GM, American Motors, and Volkswagen all recom-
mended clarifications of and minor modifications to the SEA pro-
cedure. It is agreed that an effort should be made to clarify the
proposed SEA procedure by listing deviations to the referenced
certification test procedure. This will be done before prornul—
gation of the final rule.
CM also submitted many minor miscellaneous comments. These
comments will not be summarized here but are discussed in detail in
Chapter VII of this report.
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Table of Contents Pa
I. Environmental Impact . . . 1
It. Control Technology 23
Itt. Lead Time 39
IV. Standards 43
V. Economic Impact . . 68
VI. Alternative Regulatory Approaches 122
VII. Test Procedure 131
VIII. Miscellaneous 157
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1. Environmental Impact
All comments dealing with the environmental impact of diesels
or of this proposed regulation will be discussed in this section.
This includes comments on health effects, air quality modeling and
the accompanying assumptions, impacts from other sources, sales
scenarios, and population exposures. A number of conxnertters said
that the proposed levels of control were too stringent given the
air quality impact of light—duty diesels, but did not submit any
additional data or rationalization to support their conclusions.
EPA will take these comments into consideration, but they cannot
really be analyzed. The Regulatory Analysis will examine all the
available data, and present EPA’s best judgment in this area.
A. Health Effects
Comment
Chrysler and Congressman Dingell —— alleged that this regulation is
not based on any proven adverse health effects.
Analysis
EPA has tried to make it clear that this regulation was not
based on any carcinogenic health effects of diesel particulate,
but on the impact that diesel particulate has on ambient suspended
particulate loadings. However, this does not mean that no health
effects are involved. There are known health effects connected
with suspended particulate matter, not unique to diesel particu-
late, upon which the primary national ambient air quality standard
is based. These health effects are summarized in Chapters 7 and 9
of “Airborne Particles,” National Academy of Sciences, November
1977, EPA—60011—77—053.
Comment
The Department of Energy —— suggested that EPA should emphasize the
fine particulate fraction of both diesel and overall particulate
emissions as this is where the most significant health effects
may occur.
Anal ys is
EPA agrees that the small size of diesel particulate should be
emphasized with respect to health effects and to the emissions from
other sources. The final Regulatory Analysis should contain an
additional section outlining the health effects of fine particles.
Also, the chapter concerned with cost effectiveness should examine
control strategies on a fine particulate basis as well as on a
total particulate basis.
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Comment
Ford —— claimed that EPA has the burden of proving that its stan-
dards can be met with control technology which will pose no other
unreasonable health hazard. In other words, EPA must demonstrate,
or at least ascertain, that the control techniques with which it
establishes technological feasibility will pose no unreasonable
health hazards under Section 202 (a)(4) of the Clean Air Act, prior
to promulgating art emission standard.
Analysis
While this comment can have general implications for EPA
policy, this discussion will restrict itself to the issue at hand,
that of diesel particulate standards. The comment is directed at
the possibility of a control technique, such as a trap—oxidizer,
being required to reduce the total mass of diesel particulate
emissions while at the same time increasing the total toxicity of
the particulate, or introducing a new health hazard into the
environment. EPA recognizes that such an occurrence is a possi-
bility, and we appreciate Ford’s concern in this regard. Unfor-
tunately, Ford suffers from the same inability to provide any
conclusive data on the subject as does EPA. In fact, Ford did not
submit any data supporting its claims. We, on the other hand, do
have preliminary results from our in—house trap—oxidizer test
program. They indicate that the particulate samples collected from
the exhaust following the trap—oxidizer contain lower percentages
of adsorbed organic matter than particulate samples obtained
without the trap—oxidizer. While not conclusive by any means,
these preliminary results support our expectation that it would be
unlikely that there would be any increase in toxicity due to the
addition of a trap—oxidizer. EPA intends to submit similar samoles
for bioassay testing.
At this time, EPA cannot absolutely demonstrate that diesels
with trap—oxidizers will not be found to pose an “unreasonable
risk” under Section 202(a)(A) of the Clean Air Act. If they are
found to present such an unreasonable risk, it will likely be
because of the inherent properties of the engine—out diesel exhaust
and not because of any artificial effect of the trap—oxidizer on
the engine—out exhaust. EPA has consistently affirmed that any
final determinations about the public health acceptability of the
diesel engine would have to await the results from the various
health effects research projects now in progress. It would be
impossible to make such a determination now on the risks of en-
gine—out diesel exhaust, and would be equally impossible to make
such a determination about diesels with trap—oxidizers (since the
final design is not now known). Given this reality, EPA has
concluded that the most appropriate action is to promulgate “stan-
dards which reflect the greatest degree of emission reduction
achievable” (Section 202(a)(3)(A)(iii) of the Clean Air Act,
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emphasis added), as mandated by Congress, which clearly implies
that mass reduction is the criteria to be considered, as long as
more conclusive health effects evidence is unavailable. Should
evidence be obtained in the future proving that the trap—oxidizer
increases the public health risk of the diesel engine, EPA would
clearly take action so as not to require its application.
Comment
Dr. Farkus of the University of Waterloo and Ford —— asked EPA to
include any data in their analysis which shows diesel particulate
to have unusual toxic properties with respect to general suspended
particulate. In addition, Ford stated that EPA must perform a more
complete assessment of the health effects of diesel particulate
before a standard could be set and that it should not be based on
mass but on a more appropriate measure of diesel particulate’s
effect on health.
Analysis
The Regulatory Analysis for the final regulation will include
a section on the health effects of suspended particulate and will
describe those properties of diesel particulate which would tend to
increase or decrease its non—carcinogenic health effect relative to
typical suspended particulate.
EPA agrees with Ford that a more comprehensive assessment of
the health effects of diesel particulate emissions is needed; in
fact, EPA and several other parties are currently involved in
extensive diesel health effects research programs. The final
determination of the acceptability of the diesel engine must await
the conclusion of these studies. At the same time, Congress
mandated particulate standards to “reflect the greatest degree of
emission reduction achievable” by 1981, and EPA has responded with
regulations that are based on the most recent data available.
These standards are based on mass emission rates, which is just-
ifiable on the grounds that the NAAQS for total suspended part-
iculate is based on mass and that a significant number of air
quality regions exceed the NAAQS for total suspended particulate.
In addition, as noted above, the final Regulatory Analysis will
include additional consideration of the properties of diesel
particulate which make it especially hazardous to human health.
The concern over the possible toxic or carcinogenic properties of
diesel particulate is even more reason to promulgate standards
promptly. Delaying action indefinitely in order to make one final
determination of the acceptability of the diesel would allow
diesels to emit at uncontrolled levels indefinitely, and would have
air quality and public health implications. Should the results
from the diesel health effects studies indicate that a refinement
of the particulate standards was needed, EPA would certainly take
action to do so. The prudent action at this time is to reduce
diesel particulate emissions as much as is technologically feas-
ible.
3
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B. Air Quality Modeling — General
Comment
The Council of wage and Price Stability —— questioned that esti-
mated maximum 24—hour concentrations of diesel particulate could be
compared to the 24—hour NAAQS, unless it can be shown that the
maximum diesel impact occurs in the same time period as the maximum
24—hour TSP levels.
An a ly s is
The Council brought up a very good point that was not addres-
sed in the Draft Regulatory Analysis. However, the first question
which needs to be answered is whether it is the timing of emissions
or the timing of meteorological conditions which has the greatest
effect in causing exceptionally high ambient pollutant levels. The
answer is quite obviously meteorological conditions. Air pollution
episodes are not caused by a sudden upsurge of emissions. They are
caused by adverse meteorological conditions which aggravate the
effect of the same emissions which last week caused no harm.
Short—term concentrations, such as 1—hour, 3—hour, and possibly
8—hour concentrations can be dependent on emission patterns since
there are wide ranges of vehicle usage and industrial output
throughout the day. Day—to—day variations are not nearly as
great and could not produce the variations that are seen in ambient
pollutant levels.
Returning to the original comment, the estimated maximum
24—hour concentrations of diesel particulate are those concentra-
tions that would result from adverse meteorological conditions
occuring on the average of once a year. The maximum 24—hour
concentrations occuring from other sources will occur during the
same adverse meteorological conditions (i.e., during the same time
period). Thus, it is our conclusion that the 24—hour maximum
concentrations determined in the Draft Regulatory Analysis can be
compared to the 24—hour NAAQS.
Coesne n t
The Council of Wage and Price Stability and Congressman Kildee ——
both claimed that EPA did not demonstrate that Kansas City was
representative of the rest of the nation.
Anal y s is
EPA recognizes that no special effort was made to show Kansas
City to be representative of the rest of the nation, or at least
representative of the metropolitan portion of the nation. In the
final Regulatory Analysis, independent estimates of the diesel
impact in more cities, including Chicago, New York, and Los
Angeles, should be made, and this will place the Kansas City
results into context with the rest of the nation.
4
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Comment
Congressman Dale E. Kildee, the Department of Energy, and the
Council of Wage and Price Stability — — all claimed that EPA over-
estimated the air quality impact of diesels, because the Air
Quality Dispersion Model used in the impact study tends to over-
estimate mobile sources.
An a ly s is
EPA requested that PEDCo support the statement in their
analysis that the AQDM overestimates mobile source pollutant
concentrations.1/ PEDCo could not provide any substantial evidence
to support their statement.
In reviewing the basic theory of AQDM, EPA found that the
model is generally expected to underestimate mobile source contri-
butions to some degree. This is due to the fact that AQDM assigns
all emissions in a grid to a virtual point source at some point
upwind of a receptor. Rather than treating the dispersion of
diesel particulates as a microscale line source, the area source
algorithms in AQDM treat it as a region—wide source. This may lead
to some underestimation, certainly in microscale diesel particulate
concentrations, and possibly in the area—wide estimates since only
receptors near the virtual source may be properly exposed.
Due to the lack of validation exercises for completely re-
viewing the technical adequacies of AQDM, no quantitative estimate
of any error can be made. Region—wide dispersion estimates of
mobile source diesel particulates such as performed by PEDCo are
probably well within the practical application limits of AQDM and
should be acceptable.
Comment
The Council of Wage and Price Stability and the Department of
Energy —— both said that the EPA overestimated the increase in
traffic which would occur in downtown areas.
Anal y s is
The growth rate used in the Draft Regulatory Analysis was 36%
in 20 years or 1.55% per year, compounded. This figure represented
a prediction for the Kansas City metropolitan area as a whole. As
such, it likely overestimated growth in the central city and
underestimated growth in the suburbs. Because with this regulation
1/ Nelligan, Robert E., Director, Monitoring and Analysis Divi—
sion, EPA, “Information Concerning Particulate Emissions for
Nonmobile Sources,” Memorandum to Charles L. Gray, Jr., Director,
Emission Control Technology Division, EPA, July 11, 1979.
5
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the primary interest lies in the central city region, it would be
more accurate to use a growth rate more suitable for this area. As
it has been common to use a 1% growth rate in predicting CO
emissions (see “An Analysis of Alternative Motor Vehicle Emission
Standards,” DOT, EPA, FEA, May 1977), which is an urban core
problem, it would appear that a 1% growth rate would be suitable
here also. It should be noted that EPA policy has been to use a 2%
growth rate in predicting oxidant concentrations since this is more
of a metropolitan regional problem.
Comment
Chrysler —— asserted that EPA cannot use measurements of gaseous
pollutants to predict the levels of diesel particulate due to
differences in dispersion characteristics.
Analysis
Chrysler was the only commenter to raise this issue. General
Motors, on the other hand, obviously disagreed as they made predic-
tions of ambient diesel particulate levels using measured ambient
levels of carbon monoxide (an indicator of mobile source emis-
sions). EPA also disagrees with Chrysler. We believe that there
is adequate evidence available which shows that small submicron
particles disperse essentially as a gas.2/
The same conclusion can be reached from a different route. In
section D (on roadside impact), the appropriateness of the Record
correlation to determine roadside diesel particulate impacts is
challenged. EPA agrees. The problem with the correlation is
that it is based on measurements of TSP near roadways. This
particulate matter contains many large particles from reentrained
dust and tire wear, which do not disperse at all like diesel
particulate. Diesel particulate is submicron in size and disperses
more like a gas than what is typically thought of as particulate,
and thus gaseous surrogates are the best indicators available for
diesel particulate modeling.
Comment
Chrysler, the Department of Energy, and the Council of Wage and
the Council of Wage and
Price Stability —— all claimed that EPA erroneously assumed that
particulate emissions from stationary sources would remain con—
St ant.
2/ Cadle, Steven H., et. a ].., “General Motors Sulfate Dispersion
Experiment: Experimental Procedures and Results,” JAPCA , Vol. 27,
No. 1, January 1977, pp. 33—38.
6
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An a ly s is
EPA refers all commenters to a table taken from an EPA report
dated May 1976.3/ The table has been reproduced here and follows.
The report examines the potential for reducing particulate emis-
sions from stationary sources through Federal standards. As can be
seen, 1990 emissions could increase as much as 18.6% or decrease as
much as 23.2% (Strategy #3) from 1975 levels. However, Strategy #3
is really not practical since EPA never contemplated setting all
the standards in 1975, nor did it have the manpower to do it. The
group designated FS (Strategy #5 and on) implies fuel switching is
necessary to control emissions, either to oil or natural gas. From
the current status of the nation concerning energy, it is pretty
obvious that we are not going to restrict coal usage and force
conversion to oil or natural gas. A strategy with the FS group
postponed should then be chosen. The RD group contains those
industries where research is needed to develop suitable control
technologies. As of mid—1979, none of these standards have
even been proposed. It is then reasonable to choose a strategy
which postpones the RD group, also (Strategy #6). As can be seen,
this already reduces the potential reduction in stationary source
emissions to 6.7%. Even this strategy, however, requires 6 new
standards to be set each year. Beginning in 1975, that would have
required 24—30 new standards to have been set to date. So far,
only 9 standards have been set, and these have had priority rank-
ings (largest emission reduction receives a ranking of 1) of: 2, 4,
6, 8, 13, 32, 33, 37 and 39. From this it is evident that even the
6.7% reduction will not be attained. Strategy #8 shows the result
of skipping only one large source, medium—sized boilers (priority
3). The result is a 5.7% increase in overall emissions in 1990.
To date, a standard has riot been proposed for medium—sized boilers.
Strategy #8 would appear to be close to the plan that has been
followed since 1975, except that it still overestimates the number
of standards to be promulgated per year and it assumes that those
standards will be set itt order of greatest potential reduction,
which is not occuring. The 0.7Z reduction in overall emissions in
1990 is still optimistic. From all of this, it is quite reasonable
to predict no reductions in stationary source emissions between
1975 and 1990.
C. Projections of Diesel Sales
Comment
General Motors, the Department of Energy and Congressman Dale E .
3/ “Priorities and Procedures for Development of Standards of
Performance for New Stationary Sources of Atmospheric Emissions,”
OAQPS, EPA, May 1976, EPA—450/3-76020.
7
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Particujates Priority Strate v Summarva
Standard
Setting Rate
(no. /vr)
EmIes1on
(10’ tpy)
14.08
11.48
8.72
9.12
9.31
I Change
1 ro 1975
• 4
+10.2
—16 • 2
—12.)
—10.5
Emission.
( 10 ’ tpy)
16.56
12.34
7 • 99
3 • 39
8 • 60
I ,
Prloriti Strategy -
1. State standard. only
Naximum
Rate
Emission
1983
1990
2 Change
from 1973
Efifrienc
Ratio (2.)
(10’ tpy)
(yr)
-
16.56
--
1990
-
+59.3
91.0
2. Only extstLng 11 51’S and state tendarde
3. All 1151’S set In 1975
12.34
10.40
1990
1915
18.6
-23.2
0.0
100.0
4. lISPS set in Ta—Tn order 6
10.43
1915
—19.3
90.7
5. Postpone RD group 6
(UN/RU)
10.43
1975
—17.3
85.9
6. Postpone ES and RD groups 6
(tIN/ES/Rn)
10.45
1916 9.97
—4.1
9.71 —6.7
60.5
1. Postpone 11CR, FS, RD groups 6
(UN/NCR/ES/PD)
10.45
1976 9.99
— 3.9
9.73 —6.4
59.9
8. Same as 7 wIth boilers (10—250x10 6 6
8tu/hr) in ES group
(UN/NCR/ES/PD)
10.52
1980 10.37
— 0.3
10.33 — 0.7
46.2
9. Postpone all constraint groups 6
( UN/NCR/EQ/ES/PD)
10.45
1976 10.00
— 3.8
9.75 — 6.2
.
59.4
10. Same as 9 with UN sources less than 6
3000 tpy delayed with NCR group
( UNeftIcRf/EQIF 5,Rn)
10.45
1976 9.99
3.9
9.73 — 6.4
59.9
11. Same as 10 4
10.66
1911 - 10.08
— 3.1
9.84 — 5.4
57.5
12. Same as 10 10
10.66
1976 9.86
— 5.1
9.13 —12.2
73.6
13. Same as 12 with ES and RD excluded 10
10.44
1976 9.99
— 4.1
9.63 — 7.3
62.
14. Postpone revised NSPS 6
(uue,HCRI,Eq/rs/Iw,Es (revised))
10.45
1976 10.27
— 1.3
10.29 — 1.0
47.0
5 Ststlonary sources only.
bAll strategies exclude standards for group with no
order unless a specific constraint is Involved.
Cgxcept for Strategy 1, all strategies assume existing 1151’S to
least a 5—year delay In addition to other constraints that may
dC PUtCd from the formula ((E 2 _F strategy)I(Ei_E 3 )ii 99 o x 1001;
sources with Ta—Tn > 3000 tpy included.
1 Unconstrained sources with Ta—Tn < 3000 tpy included.
be in ef1 ct in
be involved In
i.e., Eqn 3—15
1915. Except for
the revision.
where E 2 (Strategy
Strategies 1—4,
2) Ia E and
group Includes all sources
all revised lISPS are subject
£3 (Strategy 3) 1.
in
to
Ta-T n
at
demonstrated control technology (NC). The unconstrained (UN)
-------
Kildee —— all asserted that the sales projections for light—duty
diesels used in the Regulatory Analysis are unrealistic.
Anal y s is
The above commenters have stated that the diesel sales projec-
tions used in the Draft Regulatory Analysis are too high. Unfor-
tunately, the commenters were not much more specific than that.
General Motors did project their diesel sales through 1985 and, via
their CAPS proposal, through 1990. The Department of Energy
suggested that EPA use the Department of Transportation’s projec-
tions. The source of this projection was not given and only the
1985 projection was stated, 9%. We have examined the Depart-
ment of Transportation’s most recent Report to Congress on fuel
economy, 4/ and the only projection of diesel sales found was 10%
in 1985. Congressman Kil.dee did not recommend any alternative
projections.
The range of diesel sales projections used by EPA in the Draft
Regulatory Analysis are shown in Table I—i. While both scenarios
reach 10% and 25% diesels rather early (1983), both scenarios
remain constant at that level through 1990 and on. This latter
aspect should be remembered when comparisons are being made against
the projections of the early years. While 25% in 1983 may be quite
high, 25% in 1990 is not unreasonable, particularly when it only
represents an upper limit. As a best estimate, EPA chose a diesel
penetration halfway between the two scenarios of Table I—i. Some
commenters have centered their attention on the higher scenario
(25%) as if this was the EPA’s best estimate. Our best estimate
for a final diesel penetration was only 17.5%, with a possible
range of 10—25%.
It would be useful at this time to perform a rather detailed
estimate to determine how reasonable the current scenarios really
are. In Table 1—2 a breakdown of 1978 sales of light—duty vehicles
is shown by manufacturer. For the purposes of this analysis it
will be assumed that these percentages will remain constant in
future years. In Table 1—3 the GM projections of their own diesel
sales are shown. The projections between 1981 and 1985 have been
taken directly from GM’s formal comment to the rulemaking. The
projections for 1986 and on have been calculated from a table
contained in GM’s CAPS proposal, which shows GM’s average diesel
particulate levels under a series of CAPS standards. The percen-
tage of diesels was found by dividing the CAPS standard by the
average diesel particulate level. Also shown in Table 1—3 are
estimates of industry—wide diesel penetration which GM used in the
air quality analysis contained in their NOx waiver request.
4/ “Automotive Fuel Economy Program, Third Annual Report to Con-
gress,” NHTSA, DOT, January 1979, DOT—HS—803777.
9
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Table I—i
Percentage of New Vehicle Sales
Powered by Diesel Engines
Light—Duty Vehicles
and Trucks
Model Year Case A Case B
1977 0.5 0.5
1978 0.5 0.5
1979 2.0 5.0
1980 4.0 10.0
1981 6.0 15.0
1982 8.0 20.0
1983 10.0 25.0
1984 10.0 25.0
1985 10.0 25.0
1986 10.0 25.0
1987 10.0 25.0
1988 10.0 25.0
1989 10.0 25.0
1990 10.0 25.0
10
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Table 1—2
Manufacturer
General Motors
Ford
Chrysler
AMC
VW2/
Mercedes —Benz
Volvo
Fiat
BMW
Audi
Peugeot
Other Imports
New Car Sales
5,385,282
2,582,702
1,146,258
170,739
239 , 306
46 ,695
50,880
60,435
31, 457
40,878
9,061
1,544,385
Percentage of
New Car Sales
47.6%
22.8%
1( lC/
Iv • 1 1.
1.5%
2.1%
0.4%
0.4%
0.5%
0.3%
0.4%
0.1%
13.7%
1/ Automotive News, 1979 market Data Book Issue, April 25, 1979,
pp.18 and 52.
2/ Domestic and imported.
Breakdown of New Passenger Car Sales in the U.S.
by Manufacturer — 1978 1/
TOTAL
11,308,078 100.0%
11
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Table 1—3
General Motors’ Projections of the Percentage
of Diesels in New Light—Duty Vehicle Sales
Model Year GM Fleet !/ Total Fleet 2/
1981 4.2% 4.7%
1982 8.9% 7.5%
1983 11.1% 8.9%
1984 12% 9.5%
1985 13.8%
1986 17.5%
1987 22%
1988 23%
1989 24%
1990 25%
1/ Source: 1981—1985 — GM ’s comment on the NPRN for light—duty
diesel particulate regulations; 1986—1990 — derived from GM’s CAPS
proposal presented to the EPA on 3/16/79.
2/ Source: GM’s air quality analysis contained in their request for
a diesel NOx waiver.
12
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We now have enough information available to determine GM’s
contribution to the diesel fleet, but we still need the fraction of
diesels to be sold from the other manufacturers. None of these
manufacturers gave EPA projections of their diesel sales, but
reasonable projections can be made from the information available.
Table 1—4 lists the various manufacturers, other than GM, who are
expected to sell diesels in the 1980’s in the U.S. Others, such as
Toyota and Datsun, may also sell diesels, but their plans to this
date are too questionable for reasonable projections to be made.
Their omission will contribute to the conservativeness of our
estimates. Starting with the group of small foreign manufacturers
who do not sell diesels in the U.S. to date, we project that
overall Fiat, Volvo, and BMW will reach 10% diesels in 1985
and 20% in 1990. The desire for greater fuel economy should drive
this increase particularly for Volvo and BMW. We have determined
that this is reasonable by citing the situations of Mercedes—Benz
and Peugeot, who both currently sell about 60% diesels.
We have projected that both Mercedes—Benz and Peugeot will
increase their market penetration through 1990. Currently selling
about 60% diesels, we have projected diesel sales of 75% (1985) and
90% (1990). Mercedes—Benz in particular appears to be turning more
and more to the diesel for fuel economy improvements.
Volkswagen currently (1979) sells about 100,000 diesels per
year and they have testified to the EPA that they expect this to
remain the same in the near future. This amounts to 42% of their
1978 sales, domestic and foreign. Following their statements, this
figure has not been changed through 1985. For 1990 though, we
thought it unreasonable that Volkswagen would not increase produc-
tion of diesels especially given the popularity of their current
models. Taking this into account, we have projected a 50% increase
in the diesel’s share of Volkswagen’s sales for 1990, up to 63%.
The last three manufacturers are Ford, Chrysler and American
Motors. Chrysler has been developing a 6—cylinder diesel for
some time, and ANC appears to be in a position to buy diesels from
other manufacturers. With General Motors moving ahead strongly
with diesels, and the fuel economy advantage of the diesel being
relatively cheap compared to other fuel—saving techniques again it
would be unreasonable to project Chrysler and ANC staying out of
the diesel market. We have projected 10% (1985) and 20% (1990)
diesels for both manufacturers. These represent figures somewhat
below those of General Motors. While these projection.S might
appear high to some, an examination of the total sales involved
shows the reasonableness of the figures. For American Motors, 10%
of their 1978 sales would be only 17,000 vehicles, and 20% would be
34,000 vehicles. Volkswagen sold 30,000 diesels in the second year
they were offered (1978). For Chrysler, 10% of their 1978 sales
would be 115,000 vehicles and 20% would be 230,000 vehicles.
13
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Table 1—4
Projected Percentage of Diesel—Powered Light—Duty
Vehicles Sold by Manufacturer
Manufacturer 1985 1990
Ford 10% 15%
Chrysler 10% 20%
ANC 10% 20%
Vw !/ 42% 63%
Mercedes—Benz 70% 90%
Peugeot 70% 90%
Volvo, Fiat, BMW 10% 20%
Includes Audi.
14
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General Motors has primarily been marketing their diesels through
their Oldsmobile division which is about the same size as Chrysler.
Since General Motors was able to produce and sell 180,000 diesels
in their second year of production, it is certainly reasonable that
Chrysler could reach that level in 11 years. Given General Motors
commitment to diesels, it would be difficult for AMC or Chrysler to
remain competitive without a comparable capacity of their own.
Finally, we are left with Ford. Their question is PROCO vs.
diesel. It is a certainty that they will produce one of the two
engines. While Ford clearly identifies PROCO as their primary
project, there is ample evidence that Ford is going to have a
diesel program ready as a backup if something goes wrong with
the PROCO. Ford recently contracted the services of Cummins Engine
Co. to perform the engineering designs for their diesel program.
Given the length of time that Ford has been working on the PROCO
without production being established, the emphasis being put on the
back—up diesel program, and the on—going diesel program at compe-
titor GM, the chances appear good that Ford will produce diesels.
The desire for fuel efficiency exists today, and the PROCO is yet
unproven, both in the manufacturing process and in the field.
Taking all of this into consideration, we project Ford converting
10% of its sales to diesels by 1985, and 15% by 1990. The latter
value (15% vs. 20% for Chrysler and 25% for General Motors) re-
flects the greater possibility of PROCOs being produced in signifi-
cant numbers by 1990.
Combining the figures in Tables [ —2, 1—3, and 1—4, the overall
percentage of diesels being sold in 1985 and 1990 can be deter-
mined. In 1985, the diesel fraction is projected to be 11.4%, and
in 1990, 19.7%. To project the diesel fraction of vehicle miles
travelled, similar diesel fractions are needed for other years.
For the sake of simplicity, the GM industry—wide projections will
be used for 1981—1984 (see Table 1—3). Simple interpolations
between the 1985 and 1990 values will be used for all manufacturers
except General Motors for 1986 through 1989. The projections shown
in Table 1—3 will be used for General Motors. After 1990, we will
simply assume that the diesel penetration holds constant at 20%.
All these values are shown in Table 1—5.
To determine the diesel fraction of total vehicle—miles
travelled, the breakdown of vehicle—miles travelled by model year,
shown in Mobile Source Emissions Factors 5/, will be used. The
result is that 13.2% of the vehicle miles travelled by lightduty
vehicles will be by diesel in 1990 and 18.3% in 1995.
The diesel penetration scenarios shown in Table I—i yield very
similar results. In 1990, 9.1—22.9% of light—duty vehicle miles
5/ Mobile Source Emission Factors, EPA, March 1978, EPA 400/978
005, Table I—S.
15
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Table 1—5
Year—by—Year Projections of the Diesel Fraction
of Light—Duty Vehicle Sales
Diesel
Model Year Fraction (% ) 1/
1981 4.7%
1982 7.5%
1983 8.9%
1984 9.5%
1985 11.4%
1986 13.8%
1987 16.5%
1988 17.6%
1989 18.7%
1990 19.7%
1991 20%
1992 20%
1993 20%
1994 20%
1995 20%
!/ Sources: 1981—1984 Table 1—3;
1985, 1990 Tables 1—2, 1—3, 1—4;
1986—1989 linear assumption between 1985 and 1990
levels;
1991—1995 assumption that diesel penetration levels off
after 1990.
16
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travelled are projected to be diesel, and in 1995, 10—25%. The
best estimate scenario (halfway between the two scenarios of Table
[ —1) would yield projections of 16% in 1990 and 17.5% in 1995.
While the two sets of scenarios yield similar results for 1990 and
1995, the more recent scenario shown in Table 1—5 gives a much more
accurate prediction through the 1980’s. As accurate estimates of
diesel penetration in the 1980’s will be needed for economic
analyses and the analysis of alternative standards, it appears that
the more recent scenario (TabLe 1—5) should be used in the Regu-
latory Analysis. However, a range of values would be appropriate
to indicate the potential error in these predictions. Two scen-
arios based on Table 1—5, one increased by 25 percent throughout
and one decreased by 25 percent throughout, should satisfy this
requirement.
D. Roadside Impact
Comments
Ford and the Department of Commerce —— objected to the use of a
roadside impact determined three meters above and four meters from
the road when EPA guidelines for monitor siting would not allow a
monitor to be located that close to the road.
The Council of Wage and Price Stability —— asked that unless EPA
can better justify using the roadside impact as a basis for con-
trol, only the regional impact should be used.
Analysis
The EPA guideline referred to was published in the Federal
Register on August 7, 1978, pages 34892—34934. This guideline
requires that ambient TSP monitors be located at least 5 meters
away from, and 15 meters above a roadway, or at least 25 meters
away from, and 5 meters above a road, or further away from a
roadway than a line drawn between the above mentioned locations.
There are two reasons for this restriction. First, monitors
located closer to roadways do not generally represent 24—hour
population exposures; people do not generally locate in such close
proximity to streets for such periods of time. Second, monitors
located closer to roadways would actually be in the concentrated
plume of particulate emitted and generated by traffic. Except for
special purpose monitoring studies, where the objective is to
determine the impact of a single source, ambient monitors should
not be located so as to measure the plume of a single source.
In the Draft Regulatory Analysis, the air quality dispersion
model used to perform the primary air quality impact study in
Kansas City only yielded ambient diesel particulate levels on a
neighborhood scale (2 kilometer by 2 kilometer grids). Because
many people would be exposed to higher concentrations at least part
17
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of the day, due to living, working or traveling on or near a
street, the roadside impact was estimated. As such, the roadside
impact, or any localized impact has an important role to play in
any regulatory decision. While it is “generally” true that no one
resides very close to highways for periods of 24 hours, it is
important to determine the exposure of taxi and bus drivers, Street
vendors and apartment dwellers who live very close to busy streets
and may be exposed for eight hours or more. Monitors to be used in
nationwide comparisons must have somewhat uniform locations and be
limited in number, which precludes the monitoring of any one
source. At the same time, if people are breathing air from the
plume of a source, it is the Agency’s responsibility to ensure that
those people are protected.
However, care must be taken to use any estimates of localized
impacts in a responsible way. It would appear that the Draft
Regulatory Analysis used the roadside impact without the necessary
qualifiers (e.g., time of exposure, exposed population) and thereby
placed too much emphasis on it. These areas should be corrected in
the final version. In addition, EPA should attempt to better
characterize the localized impacts used. Rather than simply using
a roadside impact, impacts in street canyons, freeways, and actual
urban monitoring stations should be determined. This should aid in
using these localized impacts in a responsible manner.
Comment
General Motors —— raised the issue of why the Draft Regulatory
Analysis quoted its roadside impact at 17,000 vehicles per day,
while the PEDCo study it references quoted 25,000 vehicles per day.
Also, General Motors claimed that EPA arbitrarily assumed that the
roadside concentrations would exceed the regional concentration by
a factor of 11.
Analysis
As to the first comment, PEDCo used the following correlation
to determine the difference between roadside and regional concen—
trat ions:
C = (T/r) (0.265sin 2 0 + 0.O7cos 2 0)
Where: C = average contribution of paved road to measured TSP,
O = arctan (z/x);
T = average daily traffic, vehicles/day;
18
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r slant distance between monitor and roadway, ft.;
z = sampler height, ft.;
x = horizontal distance between roadway and monitor, ft.;
PEDCo determined that the existing TSP samplers averaged 7 meters
in height and 31 meters from roadways carrying 17,000 vehicles per
day. These locations were taken to represent regional ambient
concentrations. The roadside location was chosen as 3 meters above
ground, and 4 meters from a road carrying 25,000 vehicles per day.
Using the above correlation, PEDCo determined that the difference
between the regional and roadside impacts was a factor of 11. Upon
repeating the calculations, we found that the factor of 11 was
obtained simply from the difference in location (height and dis-
tance from road) without including the increase in traffic. With
the increase in traffic, the factor rose to 16.5. Rather than
increase the factor to account for the error, the roadside traffic
condition was reduced to 17,000 vehicles per day to keep the factor
at 11.
Comment
General Motors and Toyota —— both claimed that EPA’s roadside
impacts were too high, because the correlation was based on mea-
surements which included tire wear and reentrained dust (i.e.,
larger particles) which have different dispersion characteristics
than diesel exhaust particulate.
Analysis
The Record correlation was based on measurement of TSP near
roadways, which would include larger particles as well as smaller
ones. Since the larger particles would have different dispersion
characteristics than the submicron diesel exhaust particulate, it
does bring into question the ability to apply the correlation in
this case. One would expect that the larger particles would not
disperse as fast as the smaller particles and would settle out at a
faster rate. Both tendencies would lead to a steeper concentration
gradient for the larger particles. Since the correlation was used
to determine roadside concentrations from regional concentrations,
this would lead to an overestimate of the roadside concentrations
of the smaller particles. Because of this, Record’s correlation
should not be used to estimate the roadside concentrations of
diesel particulate.
Both General Motors and Toyota submitted data in support of
their statements. These data should be included in the final
Regulatory Analysis.
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E. Population Exposure
Cont inent
The Council of Wage and Price Stability —— said that the nationwide
population used in the population exposure calculations was over-
estimated. The Census Bureau now estimates the nationwide popula-
tion to be 236—255 million people in 1990.
An a ly s is
Any population exposure used in the final Regulatory Analysis
will be revised to use the latest Census Bureau figures.
Comment
The Department of Energy —— made the objection that the population
exposure is based on many questionable assumptions and, extrapola-
tions, particularly the extrapolation of the Tn—State population
exposure distribution to the Kansas City area and then the nation.
The population exposure should be improved or deleted.
Analysis
There can be no argument against the comment that many assump-
tions and extrapolations were made to estimate the nationwide
population exposure to diesel particulate. Most of these assump-
tions and extrapolations are sure to contain some error, in both
directions. For the purposes of this regulation, rather than
defending the exposure estimate, it would appear best to delete it
from the analysis. This regulation is based on the diesel’s impact
on overall TSP levels and not on a population exposure to an
absolute level of diesel particulate in the atmosphere, as a cancer
risk assessment would require. For the purposes of this regula-
tion, estimates of ambient levels of diesel particulate should be
sufficient to demonstrate the diesel’s impact on the nation’s
ability to meet the NAAQS for TSP.
While the population exposure will not be used for this
regulation, EPA may use it in the future when its need is greater
and time allows for a discussion of the various assumptions that
were made. While its limitations must be recognized, it is likely
the best estimate of its kind available.
F. Recommendations
As a result of the above analyses, the following changes
should be made in the Regulatory Analysis:
1) In the area of health effects, a section should be added
describing the adverse health effects of suspended particulate
20
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matter, including the effect of fine particulate matter. The
aspect of fine particulate should also be emphasized in the chapter
dealing with cost effectiveness. The assertion that EPA could not
promulgate this regulation until it had demonstrated that none of
the control techniques used to comply with the regulation pose
unreasonable risk under Section 202(a)(4) of the Clean Air Act has
been rejected.
2) With respect to air quality modeling, the assertion that
the maximum 24—hour estimates of ambient diesel particulate levels
could not be directly compared to maximum 24—hour levels of TSP has
been rejected. The Regulatory Analysis should include estimates of
ambient diesel particulate levels from many cities besides Kansas
City, putting the results from Kansas City in a proper perspective
with respect to the rest of the nation. It has also been shown
that the Air Quality Dispersion Model does not overpredict the air
quality impacts of mobile sources, so no adjustments to the model-
ing results are necessary. It appears that the prediction that
vehicle use in Kansas City will increase 1.5% per year would
overestimate vehicle use in the central city area. To remedy this,
a 1.0% per year growth factor should be used in all subsequent
analyses. The assertion that measurements of gaseous pollutant
concentrations could not legitimately be used to predict diesel
particulate levels was shown to be unfounded, as was the claim that
stationary source particulate emissions would substantially de-
crease between 1975 and 1990.
3) The light—duty diesel sales scenarios used in the Draft
Regulatory Analysis should no longer be used in future analyses.
They are accurate for long—term projections (1990 and 1995), but
overestimate diesel sales in the early and mid—1980’s. In its
place should be used the scenario shown in Table 1—5, which pre-
dicts that the diesel fraction of light—duty sales will reach 11.4
percent by 1985 and 19.7 percent by 1990. To indicate a range of
possible penetrations, the values shown in Table 1—5 should be
increased and decreased by 25 percent.
4) The estimates of the roadside impact of diesel particu-
late emissions should be improved in the final Regulatory Analysis.
The correlation originally used to estimate the roadside impact
should be discarded because it was based on TSP measurements and
likely overestimated the roadside levels of the smaller diesel
particulate. To replace this correlation, more detailed scenarios
and more sophisticated models should be used. Measurements of
ambient levels of carbon monoxide, near roadways, will also be used
to estimate roadside levels of diesel particulate. Also, future
use of the roadside impact should be accompanied by the necessary
qualifications concerning the likelihood of population exposure.
5) The quantitative estimate of the population exposed to
diesel particulate should not be used in the final Regulatory
21
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Analysis. It is not necessary to this Rulemaking and rather than
burden the Analysis with justifications of all the assumptions
involved, its use should be reserved for future regulatory actions
which may require a quantitative exposure estimate.
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II. Control Technology
A. Engine Modifications (excluding turbocharging)
EPA had predicted that minor engine modifications and redesign
would make a significant contribution towards reducing partic-
ulate emissions from light—duty diesel vehicles. In the NPRM
we suggested adjustments to timing, combustion chamber and fuel
injector redesign, and insulation and derating of the engine as
potential control technologies in this regard. For the discussion
of turbocharging, see the following issue.
Comments
Fiat —— “A ten percent particulate reduction [ by adjustment of
timing] can cause a 30% NOx increase. .. .The combustion [ chamber
design] system of a diesel engine is not very flexible from
the point of view of an acceptable trade—off between emissions
and fuel consumption.... [ Redesign of fuel injectors] could be
effective especially with hole injectors. . . . [ With respect to
insulation of the engine] at present no technology is avail-
able.... [ Derating] is not correct at least for light—duty diesels.”
Peugeot —— “Delaying of the injection timing would be, of course,
beneficial on the particulate standpoint but would not be accept-
able as far as the HC are concerned. In actual practice, there is
no possibility to improve the particulates by optimization of
timing... . [ We] believe that the compression ratio modification
is not a promising way to reduce the particulates. .. [ We] think
that the [ combustion chamber] insulation is unfavorable to the
particulateg.”
General Motors —— “Injection timing data. . . at constant speed and
light load revealed that, as timing was retarded, particulates
increased but NOx decreased. On the other hand, at the same speed
but at a higher load, both particulates and NOx decreased as timing
was retarded. At a given timing, particulates were reduced as
injection supply pressure was increased; however, this reduction
was accompanied by an increase in NOx.... [ With regard to combustion
chamber design] very substantial improvements have been realized in
the relatively new Oldsmobile system....Oldsmobile personnel in the
course of their engine development program have evaluated nearly
3,000 combustion chamber! fuel injection system combinations to
date including most of the prechamber types presently in production
in competitive engines in an effort to define the optimum configur-
ation. . . . In 1980 CM plans to introduce a modified system which
incorporates a new poppet—type injector. This system will substan-
tially reduce MC and particulate emissions compared to 1978—79
production configurations.”
Ricardo —— “Ricardo feels that potential exists for optimizing the
swirl chamber engine for low particulates at light load at the
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expense of some smoke—limited performance. The maximum reduction
which could be expected from combustion changes is estimated to be
about 15% over the drive cycle. . . .Little data exists to show the
benefit of insulating the combustion chamber... .Significant gains
may be possible by improving the power/weight ratio by fitting a
more powerful engine or by lightening the vehicle. The effect
would be to increase engine air/fuel ratios during the drive cycle
which may be expected to lead to a reduction in particulates.”
Department of Energy —— “DOE’s technology analysis.. .summarized
below indicates that. . .initial control of particulates through
engine modification is possible given adequate development and
leadtime. Injection system design, injection timing, combustion
chamber design and driveline matching (or engine derating) will be
the primary means of controlling particulates.”
Daimler—Benz —— “It is common knowledge, and it is not disputed by
Daimler—Benz, that past engine modification measures have been
among the most effective means for improving today’s diesel engine.
Indeed, the quality and performance of today’s diesel engine for
application in the passenger car is directly related to engine
modifications involving the injection system, injection rate and
timing as well as the spray characteristics of the fuel nozzles
utilized in light—duty vehicle diesel engines. . . .The engine modifi-
cations which distinguish the 1979 300 D and 300 SD engines other
than turbocharging include the following modifications contained in
the 300 SD engine and not the 300 D engine:
(a) [ Mn additional hole in the prechamber increasing the
prechamber from five holes to six holes which results in a reduc-
tion of particulate.
(b) [ A]n injection pump with modified injection characteris-
tics. .. .This modification resulted in less particulate matter
emissions under part load conditions and lowered gaseous etnis—
sion [ s]
(c) [ A] modification was made to the... injection timer. This
change resulted in retarded injection timing at part load causing a
beneficial impact on particulate and gaseous emissions....
Daimler—Benz has incorporated in the model year 1980 300D engine
design all the changes noted above which were used in the 1979 300
SD engine.”
Analysis
Our position that engine modifications would be able to reduce
particulate emissions had been primarily based on the fact that
although many diesel engine designs had been optimized for smoke—
limited performance, none had been optimized with respect to
particulate emissions. Thus we expected some optimization to be
24
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possible, especially at light loads where the correlation between
smoke and particulate is much less clear. Because particulate
reductions due to minor engine modifications are strongly mariufac—
turer—specific (dependent on the existing engine design, the extent
to which that design had been optimized for smoke, the willingness
and financial ability to perform the requisite research, etc.), we
were not able to state the percentage improvement that could be
expected from such changes, and therefore did not place a great
deal of emphasis on minor engine modifications. Based on the above
comments and manufacturers’ data on 1980 certificatiOn and 1981
prototype designs, however, we seem to have underestimated the
significant reductions in particulate emissions possible through
minor engine modifications.
The position that particulate reductions due to minor engine
modifications are dependent on each individual manufacturer and
design is supported by the fact that no specific modification was
unanimously endorsed, yet almost every manufacturer found one or
more areas in which improvements could be made. CM and Fiat both
claimed that redesigned fuel injectors could be effective; in fact,
GM credited much of their very substantial particulate reduction in
their 1980 design to their new poppet fuel injectors. Combustion
chamber optimization was performed by both GM and Daimler—Benz,
with the latter adding a hole in their prechamber. An area where
some success has been achieved but where more work is necessary is
injector timing adjustments. Daimler—Benz reported particulate
reductions due to retarded timing at part load, and GM indicated
the possibility of doing likewise, but Peugeot pointed out the
necessity of optimizing HC and particulate simultaneously, and Fiat
provided data showing particulate increasing with retarded timing;
to lower particulate Fiat would have to advance its timing and
raise its NOx emissions. Derating was supported by Ricardo and DOE
but Fiat claimed it would not work for light—duty diesels because
of the part load nature of the FTP. Finally, no commenter expres-
sed any confidence in engine insulation as a particulate control
strategy.
EPA had tested a wide variety of 1979 light—duty diesel
certification vehicles when establishing the diesel particulate
baseline. Three manufacturers reported 1981 prototype particulate
data on models which we had tested as part of the baseline. The
comparison of these data is shown in Table 11—1.
We believe these data prove that engine modifications have
been a fertile source of particulate reductions in the past year.
It is very important to note that the greatest particulate reduc-
tions achieved through engine modifications were by GM and Daimler—
Benz, the manufacturers who had the highest 1979 certification
particulate levels. Thus, our belief that particulate optimization
was possible has been borne out, and even exceeded with respect to
the largest diesel engines.
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Table 111—1
Comparison of
Cert Vel icles
Particulate Levels of 1979
and 1981 “Best” Prototypes
Best 1981 Prototype
__________________ Particulate Level*
(g/mi) (g/km)
0.29—0.50 0.18—0.35
0.36—0.51 0.22—0.32
Manufacturer
General Motors
Daimler—Benz
Peugeot
1979 Baseline
______________ Model Particulate Level
(glmi) (g/km)
“260” 0 73—1 .02 0 45—0 63
“350” 0.84 0.52
240D 0.53 0.33
300D 0.83 0.52
300SD 0.45 0.28
504D 0.29 0.18
*At NOx levels of 1.5 gpm or less.
0.40
0.30
0.47
0.49
0.25
0.19
0.29
0.30
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The EPA technical staff is confident that progress will
continue in the area of engine modifications to reduce particulate
emissions. Certainly there is a strong probability of additional
reductions due to fuel injector and combustion chamber redesign
(especially for those manufacturers who have not investigated these
areas), timing adjustments and controls, and engine derating. It
is very unlikely that all of these parameters have been optimized
in just two years of development work. There is also a high
probability that other, as yet unforeseen, engine modifications
will be found that will reduce particulate emissions. For example,
in preliminary testing at the Ann Arbor laboratory, intake air
throttling has been found to reduce particulate emissions. It is
hypothesized that this might be due to reduced quenching around the
fuel droplets due to the lower air/fuel ratio of the throttled
engine. Despite the fact that intake air throttling is a rather
simple concept, and has been investigated in the past for other
reasons, no coents were received with respect to its effect on
particulate emissions. We consider it very likely that other
possible engine modification control technologies will be dis-
covered and investigated in the near future.
B. Turbochargers
EPA placed considerable emphasis upon turbocharging as a
particulate control strategy in the light—duty diesel particulate
Regulatory Analysis. Data available to us at that time indicated
that turbocharging reduced particulate emissions by approximately
one—third. This conclusion generated much discussion by the
Conm enters.
Comma nt s
Peugeot —— [ o]nly (the] addition of a turbocharger is not suffi-
cient to ensure lowering of the particulates emission. However, an
appreciable reduction of about 20% has been realized with a turbo—
charged engine which included several complementary modifications
(especially modification of the valve timing).”
Fiat —— “(Turbocharging] can be effective (up to 30% reduction of
iculates with respect to N/A engine) but it needs a long time
of development, not only to redesign the injection, intake, and
exhaust systems and to match the turbocharger to the engine for
emissions and fuel economy, but mainly to review engine design in
order to insure acceptable reliability with the increased thermal
loading and pressure.”
Ricardo —— “Results from a number of sources indicate that by
running with the higher air/fuel ratios afforded by turbocharging,
particulates can be significantly reduced....Estimates of the
reduction obtained by turbocharging vary considerably, but figures
of 25% and above are typical.”
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Daimler—Benz —— “Turbocharging is simply a means of increasing the
power output of a diesel engine with an established CID. The
application of turbocharging results in the improvement of a
vehicle’s fuel economy resulting from the engine’s increased
thermal efficiency and ability to thereby lower a vehicle’s rear
axle ratio. Turbocharging does not reduce particulate matter
emissions.”
General Motors — — “In the course of GM investigations of applying
turbochargers to the diesel engine, we have not seen any substan-
tial lowering of particulate levels by turbocharging in any of the
installations where we have comparative data.”
Ford —— “ [ C]urrently available data from turbocharged and naturally
aspirated diesel engines show mixed results.”
Department of Energy —— “Turbochargers are not an effective parti-
culate emission control device as assumed by EPA, except to the
extent they reduce fuel consumption. This is due in part to the
fact that they are not operative during a large portion of the EPA
test cycle.”
Analysis
As the above quotations indicate, there is disagreement over
whether turbocharging does indeed reduce particulate emissions.
Peugeot and Fiat were the only manufacturers to emphatically
support the application of turbocharging to reduce particulate
emissions; Daimler—Benz and General Motors denied that turbo—
charging reduced particulate; and Volkswagen, Chrysler, Ford,
Volvo, and BMW generally held that it was not clear whether turbo—
charging reduced particulate or not.
Both Peugeot and Fiat emphasized that it is not possible to
achieve lower particulate levels by simply adding a turbocharger to
an existing engine design; it is necessary to match the turbo-
charger to the engine’s intake, exhaust, and injection systems.
After doing so they reported particulate reductions of 20 and 30
percent, respectively. Surprisingly, it seems that none of the
other manufacturers have chosen to seriously investigate turbo—
charging. Daimler—Benz spent much effort in showing why it was
inappropriate for EPA to use their 1979 300 D (naturally aspirated)
and 300 SD (turbocharged) vehicles as an example of how turbo—
charging reduces particulate, because of design differences between
the two models in the 1979 model year (see previous issue). Yet
there is no evidence that they thoroughly investigated the possi-
bility of integrating turbocharging throughout their diesel model
lines. General Motors did report the results of a test program
designed to investigate the effect of turbocharging on particulate
emissions. But from what we can ascertain from their comment, the
program involved little more than turbocharger on/turbocharger off
28
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comparisons. Most of these comparisons showed turbocharging to
cause higher particulate emissions. Clearly, however, GM did not
perform the comprehensive test program one would expect if it truly
wanted to utilize a turbocharger as a particulate control device.
GM did admit that the use of a turbocharger permits the use of a
lower numerical axle ratio, and reported tests indicating that
lower axle ratios reduce particulate as well as HC, CO, and NOx
emissions, but concluded that the particulate reduction would be
“small” when using a “reasonable” decrease in axle ratio.
The comments have convinced the Agency that turbocharging can
be an effective particulate control strategy, provided a concerted
effort is made to match and optimize the turbocharger application
to the engine’s intake, exhaust, and injection systems, and that
the increased thermal efficiency is utilized to optimize transmis-
sion gearing and axle ratio for emissions rather than for increased
performance. Our initial estimate of a 33 percent reduction may
have been somewhat optimistic, but it appears that reductions of
20 to 30 percent are achievable in many cases. Clearly, however,
turbocharging is not the quick and simple control strategy that we
had considered it in the Regulatory Analysis. This has definite
ramifications with respect to lead time which will be discussed
Ln the next section.
C. Catalytic Converters
EPA had estimated that the majority of light—duty diesel
vehicles would have to utilize an aftertreatment device to meet the
proposed 1983 particulate standard. This device could be either a
catalytic converter, trap, or trap oxidizer. EPA had assumed that
such an aftertreatment device would have a collection efficiency of
67 percent.
Conime nt s
Ricardo —— “Platinum catalysts of monolithic construction are known
to be extremely effective in reducing hydrocarbons in exhaust
gases, but Ricardo has not found them to be effective in reducing
particulate emissions. It has also been found that production of
Sulfates within the catalyst can be a problem if gas oils with a
high sulfur content are used. The addition of a catalyst to a
filtering medium may, however, have a beneficial effect since
oxidation of soot depositing on the filter may be promoted.”
Fiat —— “ [ Catalytic converter] is effective in reducing by 50%
organics adsorbed on particulate, but with a strong increase in
Sulfates in the form of SO 4 because of the presence in the fuel
of large sulfur amounts....Furthermore plugging problems of cataly-
tic converters during mileage accumulation have to be solved.”
BMW —— “The main problem with an oxidation system is to provide the
necessary temperature level and sufficient oxidation time. Ade—
29
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quate exhaust temperature of approximately 600°C for particulate
oxidation may only be reached outside the CVS driving cycle.”
General Motors —— “In general, we have found no catalyst to date
which has aided in particulate reduction, although catalysts have
shown at least temporary HC reduction.”
Ford —— “ [ Clatalysts tend to have low efficiencies at the low
exhaust temperatures of the diesel. Clogging of the catalyst with
soot is a problem unless adequate temperature levels are achieved
by installing the catalyst close to the exhaust port. .. .However,
with a close—coupled catalyst, sulfate emissions may increase.”
Analysis
The primary difficulty of utilizing catalytic converter
technology to reduce diesel particulate is in continuously main-
taining both the high temperatures and sufficient residence times
that are necessary for oxidation of the particulate. Although it
appears that considerable progress has been made with converter
technology in reducing the organic component of the particulate
(see Ricardo and Fiat comments above), similar progress has not
occurred with respect to the less easily oxidized carbon (soot)
component. In addition, the possibility of greater sulfate emis-
sions is of concern, although Volkswagen reported that this could
be avoided by the selection of the proper catalyst.
Thus, unless a technical breakthrough occurs, it is unlikely
that catalytic converters will play a major role in reducing diesel
particulate emissions. It is quite possible that in the future
converters will be used for HC and organics reductions, with some
resulting reduction in total particulate emissions, and we expect
research in this area to continue. Concerning total particulate
emissions, the use of catalytic material in combination with trap
oxidizers is most promising. This will be discussed below.
D. Traps
Comments
Ricardo —— “Traps filled with alumina—coated stainless steel wool
have given particulate reductions of better than 50% over the FTP
cycle, but after about 1,000 miles the traps became blocked,
collection efficiency fell below 10%, and back pressures rose
unacceptably. The recurring problem with these devices. . .is
the very large volumes of soot which are collected.”
Daimler—Benz —— “In principle exhaust gas temperature resistant as
well as chemical resistant filters can eliminate particulate matter
from the exhaust gas stream for a limited time period with 15 to 80
percent efficiency. The main problem with these filter systems is,
30
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however, the exhaust gas backpressure buildup process which takes
place within hours. If this backpressure exceeds certain values,
performance and fuel economy are reduced while particulate matter
emissions of the engine increase. Thus, at the present time,
Daimler—Benz has found no manufacturer with the capability of
producing by 1983 trap filters which have acceptable durability and
do not result in unacceptable backpressure buildup.”
General Motors — — “Open structures of metal mesh and typical beads
have yielded particulate collection efficiency of about 60% in
properly proportioned volume and at low vehicle mileage. Trap
Capacity is limited when reasonable trap volumes are used, and some
trap materials have been destroyed under certain driving condi—
tions....The measured bulk density of particulates removed from
the walls of an exhaust system or CVS tunnel is in the range of
0.07—0.10 g/ctn 3 . At this low density for typical emission levels,
the particulate volume removed by an efficient trap may be well
over a gallon per thousand miles. This particulate bulk is not
distributed evenly through the trap material, but is concentrated
more heavily near the trap inlet. For these reasons, traps
of reasonable volume have capacity for only a few hundred miles of
operation....A study is in progress to evaluate various cleaning
methods for trap restoration by servicing with external (not
onboard) equipment. It is recognized that such methods would
require the availability of service stations of the necessary
auxiliary cleaning equipment, and would entail a possibly difficult
problem of particulate disposal at the service station. Also,
considerable driver inconvenience and service costs would likely
result. . . .No trap and cleaning technique has yet been found
which solves all the basic problems of backpressure buildup,
decreasing efficiency, blow—off under acceleration, and disposal of
the particulates once collected.”
Analysis
The particulate collection efficiencies of many trap mater—
Lals, when new, are quite acceptable. Daimler—Benz reported
i.nitial efficiencies as high as 80 percent, and General Motors
reported initial efficiencies for paper elements as high as 90
percent, and for alumina coated metal mesh, metal wool, quadralobe
catalyst beads, and alumina fiber material efficiencies of 60 to 65
percent. As mileage accumulation occurs and the particulate begins
to build up on the trap, the collection efficiency decreases and
the exhaust gas backpressure increases. A method is needed by
which the trap can be periodically “cleaned” or regenerated to
restore the collection efficiency and backpressure to desirable
levels. The regeneration technique must also be compatible with
the trap lasting 100,000 miles, as durability is a primary consi-
deration. To date, the best reported trap with respect to dura-
bility was a metal mesh trap on an Opel vehicle, run on a modified
AMA driving schedule with no hard accelerations, hills, or speeds
31
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above 45 mph. The trap survived 12,800 miles and at that time had
a collection efficiency similar to its zero—mile efficiency of 55
percent. GM reported some trap attrition and there was evidence of
some particulate blow—off and self incineration. It is in the
areas of regeneration and durability where research must be con-
tinued to optimize a particulate aftertreatment device.
It has been recognized that there are two basic classes of
regeneration: external trap servicing and on—board automatic
incineration. The latter distinguishes the trap oxidizer, which
will be discussed in the next section.
External trap restoration could take many forms. If paper
trap elements were used, chemical dipping, backward pulsed air
flow, or even low—cost changeable filters could be used. With
permanent filter cartridges, high—temperature oven incineration,
pressurized washing, chemical dipping, or sonic cleaning could be
possible techniques. At this time none of these techniques has
fulfilled the basic criteria of restoring the collection efficiency
and backpressure of any trap to desirable levels.
Another critical issue is the frequency of external servicing
and the certainty that the vehicle owner would order the servicing.
Since excessive backpressure levels can result in performance
and/or fuel economy losses, the vehicle owner would certainly have
some motivation to service his trap at regular intervals. GM has
suggested the inclusion of a bypass valve in the trap to allow
exhaust pressure to be partially relieved under certain conditions
to protect the trap. The existence of such a valve might allow a
vehicle owner to abdicate his responsibility to service his trap,
while also avoiding excessive backpressure problems which would
otherwise provide the motivation for servicing the trap. Also at
issue is the magnitude and frequency of the possible inconvenience
to the vehicle owner, and the effects that the perceived inconven-
ience may have on the public’s acceptability of the diesel.
Because of the above concerns about external trap servicing,
it is likely that on—board incineration will be the preferred
method of trap restoration. Nevertheless, should the trap oxidizer
be rejected on technical or economic grounds, we believe that traps
with external restoration could be a feasible particulate control
technology, if extensive research continues.
E. Trap Oxidizers
Comments
General Motors —— “Of the (aftertreatment] approaches investigated,
a particulate trap with onboard incineration shows the most pro-
mise, but available hardware does not meet the requirements of
a production configuration. We have not yet found a trapping
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material that exhibits good efficiency, adequate capacity, toler-
able flow resistance, and durability. We also have not identified
a control system for the incineration process. Many factors must
be considered in the development of such a system, such as safety,
effects on emissions of other pollutants, effects on fuel economy,
etc... .Currently, the most desirable solution to the trap regenera-
tion problem appears to be on—board incineration of the particu—
lates. Test data have shown that this can be effectively achieved
under certain conditions by raising the temperature of the exhaust
gases to approximately 480°C... .Two approaches to diesel particu-
late incineration are being actively pursued. The first, intake
throttling, reduces the dilution air through the engine and, thus,
increases exhaust temperature. In the second approach, the addi-
tional energy required to initiate incineration is provided by a
device such as an electric heating element. .. .Repetitive incinera-
tion over a limited few cycles has been achieved with careful
control using each of the two methods. However, it has not yet
been established by experiment or theory that nondestructive
incineration can be achieved at all possible operating conditions,
nor have the particulate collection limits for nondestructive
incineration been defined. Repetitive controlled incineration at
arbitrary operating conditions, with or without auxiliary heat
supply will likely require a complex algorithm and closed—loop
control.”
Daimler—Benz —— “As a general statement, Daimler—Benz believes that
EPA’s position fails to recognize the following difficulties
resulting from the use of trap oxidizers....:
a) The exhaust backpressure increase resulting from the use
of trap oxidizers adversely affects diesel engine performance
as well as fuel economy thereby reducing the major advantages
which the diesel engine has over gasoline engines.
b) The variable nature of the exhaust gas backpressure
resulting from the use of trap oxidizers has a direct impact
on ECR systems which can result in an EGR system becoming
ineffective....
If the exhaust gas temperatures of an engine are checked over load
and speed, it becomes clear that sufficiently high temperature
levels (for combustion] are only available in the upper load and
rpm range of an engine’s performance map. These operating ranges
are, however, rarely reached during CVS testing....Thus, Daimler—
Benz sees no possibility for the use of traps or trap oxidizers as
a means of particulate matter emission control, especially in
conjunction with turbochargers.”
Ford —— “Current technology traps and filters may have over 50%
particulate collection efficiency when new, however, deterioration
of collection efficiency is very rapid with mileage accumulation.
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Adequate exhaust temperature for oxidation of the collected parti-
culate material may be only reached outside the CVS driving cycle
so that repetitive CVS testing may not result in regeneration of
the filter. Furthermore, we are concerned that filters laden with
particulate material can be subject to accidental ignition.
Although our research for an effective regenerating oxidizer trap
is continuing, our current assessment indicates significant short-
coming in these systems at their current state of development.”
Imperial Chemical Industries Limited — — “Tests on [ trap oxidizers]
have been reported which utilized through—flow agglomerating
filters, but these were subject to high pressure drop under flow.
ICI have been investigating the use of particulate filters for
diesel exhaust for some years and this resulted in the invention of
a novel form of filter which greatly reduces the pressure drop.
The filter provides for a diffusion mechanism to remove the parti-
culate in a radial flow structure of ‘Saffil’ alumino fiber and
nickel wire. Regeneration of the filter is effected by oxidizing
the particulate principally to CO 2 when the exhaust gas temperature
reaches around 450°C in the presence of a silver catalyst. . . .It is
stressed that this submission is based only on limited data and
further evaluation and development are essential to achieve a
production device.”
Analysis
A trap oxidizer is simply a trap with a mechanism by which the
collected particulate can be periodically oxidized in order to
restore the collection efficiency and exhaust gas backpressure to
desirable levels. Many of the comments revolved around the issue
of regeneration. Most of the commenters stated that the minimum
temperature required for combustion of the particulate to be
approximately 450—500°C. Since the exhaust gas temperature of a
diesel powered vehicle operated over the LA—4 driving cycle rarely
exceeds 400°C, this raises the question of how to elevate the
exhaust temperature to the requisite levels. GM’s two suggested
approaches, air intake throttling and use of an external heat
supply, both seem promising. GM reported that over a 1,000 mile
load up and incineration test with throttling utilized to initiate
incineration and 100 mile trapping periods, the collection effi-
ciency actually improved slightly. Further research needs to be
done to examine the impact of throttling on emissions and fuel
economy. As mentioned earlier, it is also quite possible that
throttling might tend to reduce particulate formation in the
combustion chamber. The use of an external heat supply to initiate
incineration has also been shown to reduce collection efficiency
only slightly. With this technique, there is the possibility of a
dual path trap, designed with dual heating elements and a valve
which would route a small fraction of the exhaust flow to the trap
that was being incinerated, and the rest to the trap that was not.
The advantage of the dual path trap is that it would significantly
reduce the necessary power requirement.
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Volkswagen was the only other manufacturer to report any
trap oxidizer development results, but they included no durability
data. They stated that it might be possible, with the proper
catalytic material, to lower the temperature necessary for partic-
ulate oxidation as low as 350°C. If so, this would greatly reduce,
and might even eliminate the need for throttling or an external
heat supply. It would not eliminate the need for some kind of
incineration control mechanism. VW is experimenting with trap
oxidizers mounted in place of the exhaust manifold (thus obtaining
slightly higher temperatures) while GM places its trap oxidizers
further downstream in the exhaust system.
GM’s preliminary development work on the trap oxidizer indi-
cates that on—board incineration is technically feasible. Other
Concerns about on—board incineration were expressed by the corn—
menters. Certainly the emissions characteristics of a diesel
powered vehicle during the regeneration mode should be thoroughly
Lnvestigated, both from the standpoint of the regulated pollutants
and particulate, and any unregulated pollutants as well. The
Concern that the trap oxidizer could be a safety hazard should
also be fully investigated, though at this time we do not foresee
this to be a major problem.
Ford’s concern over the possibility that the regeneration mode
might not occur during CVS testing is well taken. The manufac-
turers would want regeneration to occur in order to restore collec-
tion efficiency and backpressure to original levels, and EPA would
need regeneration to take place so as to characterize the emissions
under that mode. It is recognized that the FTP may have to be
modified in order to ensure that regeneration occurs.
Daimler—Benz’s concern over the effect of increased exhaust
backpressure on diesel performance and fuel economy is overstated.
Certainly it is true that excessive backpressure can have a debili-
tating effect on the diesel engine. But assuming the optimization
of on—board regeneration, such excessive backpressure should not
Occur. GM’s 1,000 mile load up and incineration test, with 100
mile trapping periods, utilizing throttling to initiate incinera-
tion, showed backpressure to increase slightly with mileage, but
clearly indicated a trend of flattening out with time. Daituler—
Benz’s second point, of the deleterious effect of variable back—
pressure on the effectiveness of EGR systems, is a very real
Concern. We therefore are inclined to agree with GM that some form
of control over the incineration process is necessary, though it is
not clear at this time how complex that control might have to be.
Certainly EGR and backpressure could be accommodated within such a
control system.
In the Regulatory Analysis, we assumed a lifetime collection
efficiency of 67 percent. Due to the uncertainty which still
exists due to the developing nature of the technology, we cannot be
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sure whether this assumption will be verified. We have received
data which show that such efficiencies have been achieved on low
mileage tests, and expect that such efficiencies will be realistic
for trap oxidizers over the lifetime of the vehicle in the near
future.
The significant progress that has been made in trap oxidizer
development indicates that it will play a successful role in
particulate emissions control. Admittedly, application of the
technology on production vehicles is not yet feasible. Research
must be continued on regeneration control techniques and the
optimization of a trap material which can last for the vehicle
lifetime at a relatively high efficiency.
F. Fuel Modifications
EPA did not assume any particulate reduction due to fuel
modifications in the Regulatory Analysis.
Comment s
Daimler—Benz —— “EPA’S proposal makes no effort to consider the
beneficial impact on diesel particulate emisions which would result
if the contents of diesel fuel were regulated.”
General Motors —— “Changes in fuel characteristics could reduce
diesel particulates up to 25 percent, but implementation depends on
the capabilities of the petroleum industry.. . .Any significant
change in the diesel fuel supplied throughout the country would
require time for its implementation.”
Citizens for Clean Air — — “If [ a correlation is found between
aromatic content of diesel fuel and polycyclic aromatic hydrocarbon
emissions], EPA should develop standards limiting the maximum
aromatic content of diesel fuel marketed in urban areas if the
expected conversion to high aromatic synthetic fuels produced from
coal, oil shales, and tar sands should occur.”
Analysis
Potential exists for reductions in particulate matter emis-
sions due to diesel fuel n difications. The two areas which have
received the most attention are fuel additives and different fuel
blending.
Additives can reduce particulate emissons by reducing ignition
delay, catalyzing carbon combustion, and improving fuel droplet
dispersion. GM reported a 17 percent particulate reduction over
the FTP with an unknown additive. One significant drawback of
additives, of course, is that they usually contribute to other
combustion by—products that often have public health implications.
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Thus, any decision to mandate the addition of diesel fuel additives
should be preceded by comprehensive characterization and assessment
work. Although this work may be going on at this time, few results
have been reported to EPA.
A different fuel blending might also be useful in reducing
particulate emissions. Both high aromatic content and the high
final boiling point portions of diesel fuel have been hypothesized
to contribute to increased diesel particulate emissions. Thus, a
fuel blend with a lower aromatic content and less of the high
boiling point compounds would likely reduce particulate emissions.
Unfortunately, such a blend would probably result in slightly worse
fuel economy. In addition, a decision to permanently shift to a
different diesel fuel blend would necessitate major changes by the
petroleum refineries which would have definite lead time 1mph—
cat ions.
An important issue with respect to additives and fuel blending
is whether EPA has the authority to issue regulations mandating any
of the aforementioned changes. In the past, EPA deliberations
regarding fuel content have concentrated on the desirability of
removi j fuel additives or contaminants that have been shown to be
health hazards.
EPA should continue to monitor research performed in this
area, and would welcome the opportunity to work with the automotive
and petrochemical industries in reducing particulate emissions
through fuel modifications.
C. Alternative Engine
Comment
____ are considering the use of a diesel engine in our
light—duty vehicles as a back up alternative to our PROCO engine.
We continue to believe that PROCO and/or diesel are an essential
element of any plan to continue to offer a range of vehicles which
satisfy basic demand for new motor vehicles and at the same time
allow us to meet future, more Stringent fuel economy standards.
We are interested in the diesel [ as] there is real question yet on
PROCO. We are working diligently and we are enthusiastic about it
and reasonably confident. [ But] many things could still happen
before we get these things into mass production.”
Analysis
Although we have received little information on it, Ford’s
Stratified—charge PROCO (programed combustion) engine appears
to be a promising alternative powerplant to the diesel. Prehimi—
nary data reported by Ford indicates that the PROCO yields approxi-
mately the same fuel economy improvements as the diesel with the
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diesel being slightly superior in heavier vehicles but the PROCO
improving in lighter vehicles. Conversely, the PROCO does not seem
to share most of the disadvantages of the diesel. A 5.8—liter
PROCO in a 4,000—pound vehicle emitted just 0.03 to 0.06 g/mi (0.02
to 0.04 g/km) particulate with a catalyst and unleaded fuel; this
is well below the “second—step” standard of 0.20 g/mi (0.12 g/km).
It is also expected that the PROCO would exhibit less mutagenic
activity than the diesel. In a series of 15 tests, three 6.6—liter
PROCO engines in 5,000—pound vehicles emitted just 0.73 to 0.82
g/mi (0.45 to 0.51 g/km) NOx, a level that has been approached by
only the very smallest diesel vehicles. Finally, its performance
appears to be superior to the diesel and comparable to present
gasoline—fueled vehicles. Thus, the PROCO is very promising as a
technology which satisfies both environmental and energy require-
ments. The primary question about the PROCO concerns its feasi-
bility in mass production. Ford did not offer any specific predic-
tions about the cost of the PROCO, but did speculate that it might
be more expensive than the diesel due to the need for electronic
controls and an oxidation catalyst. It should be noted that the
cost of the PROCO relative to the diesel will likely improve as
trap oxidizers and electronically—controlled EGR become necessary
for diesels to meet future emissions requirements.
H. Recommendation
From the foregoing analyses, it is clear that while we were
overly optimistic about the effectiveness and availability of
turbochargers to reduce particulate emissions in the near term, we
were not able to foresee the significant reductions achieved
through engine modifications, especially by manufacturers of the
largest diesel vehicles. We continue to consider trap oxidizers to
be the most promising aftertreatment technology. Research should
continue in the area of fuel modifications.
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III. Lead Time
A. Engine Modifications
EPA had projected that there would be sufficient lead time for
manufacturers to make minor engine modifications by the 1981 model
year.
Comments
imler—Benz —— “Daimler—Benz knows of no way that in the next
three to six months any new technology can be developed or placed
into production for the control of particulate matter. Thus,
Daimler—Benz believes that the particulate matter standard estab-
lished by EPA for model year 1981 must be capable of being achieved
with presently available and adaptable technology.”
partment of Energy —— “In view of the less than six months
between the time this rule will likely be promulgated and the
beginning of 1981 model year certification, 1982 is the first model
year for which it is reasonable to expect improvements in particu-
late control....”
Analysis
As indicated in the earlier section on engine modifications,
significant particulate reductions have already been achieved by
minor engine redesign, especially by those manufacturers who
had the highest particulate levels in our baseline testing. Very
little lead time remains for the 1981 model year (many manufac-
turers will begin the 1981 certification process in late 1979)..
All that would be possible at this late date would be to fine—tune
minor parameters with respect to particulate emissions. EPA’s
conclusions regarding the particulate level achievable in 1981
should be based only on that technology that is already available
and which was discussed in the earlier section on engine modifica-
tions.
B. Turbochargers
EPA had stated in the NPRM that manufacturers would have
sufficient lead time to incorporate turbochargers into their 1981
designs, should they so desire.
Comments
General Motors —— “Using current available manpower with a normal
design program, it is estimated that GN could add turbocharging
capability on their planned V—6 and V—8 diesel engines for the 1983
Start of production. This presumes no major durability problems
requiring new engine tooling.”
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Volkswagen —— “We have investigated turbochargers for several years
and think that they can be developed without unreasonable
technical risk for the 1982 model year, although we do not regard
them as particulate control devices.”
Analysis
Very few comments were made on our turbocharger lead time
projections. With respect to 1981 production, given the reality
that most manufacturers will begin their 1981 certification process
in the fall of 1979, it is certainly true that for those manufac-
turers who have not aggressively pursued turbocharger development,
there is not sufficient time to integrate turbochargers into
production designs. This situation has been brought about partly
because turbocharging is not as “quick and simple” a way to reduce
particulate as we had previously believed, and partly because many
manufacturers have simply not moved rapidly with turbocharger
development because of their belief that turbochargers do not
reduce particulate. Nevertheless, it should be noted that Daimler—
Benz will continue to market their turbocharged 300 SD model, and
that Peugeot appears ready to introduce a turbocharged model in the
1981 model year. Neither of these manufacturers expressed any
concern over turbocharger availability problems, though certainly
their efforts are eased by the low volumes needed.
Turbochargers apparently will not be utilized by all manufac-
turers for the 1981 model year. For some manufacturers turbo—
chargers will not be available on a mass scale until 1983. The
effects of this situation on the 1981 standard should be considered
under the level of standards issue.
C. Trap Oxidizers
EPA had projected that trap oxidizers could be a viable
particulate control technology by the 1983 model year.
Comment s
Volkswagen —— “Taking into account the necessary [ trap oxidizer]
development time, assuming the best possible results at each phase,
we cannot complete development prior to mid—1982. Thereafter, 18
to 24 months are needed to purchase and set up production equip-
ment. This means the earliest possible introduction date for trap
oxidizers is the 1985 model year.”
General Motors (written comment) —— “A number of ideas and sugges-
tions have been considered in this [ trap oxidizer] program, however
only one system concept was used to estimate lead time require—
ments....Lead time is estimated to be approximately 50 months from
system design selection. Based on the current program status, this
would indicate a possibility of 1985 model year introduction.”
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General Motors (public hearing) —— “Judging by our development
results to date, [ a trap oxidizer] could not be available by the
1983 model year as postulated by EPA. Durable material and system
developments are needed plus an estimated 2 1/2 to 3 years produc-
tion leadtime after an acceptable method is defined..”
Analysis
When the NPRM was being prepared, our best estimate was that
trap oxidizers would be available for the 1983 model year. That
assessment has been reevaluated in view of the input received from
the commenters with regards to the state—of—the—art of trap oxi-
dizer technology.
As was concluded in the control technology section on trap
oxidizers, more basic research still needs to be done in the areas
of regeneration initiation and control, and trap durability.
Enough progress has been achieved to convince EPA that a successful
trap oxidizer can be developed, but as of this time, no design has
proven to have the required collection efficiency over the desired
length of time. With the research that has been, and is, going on
with regards to trap oxidizer development, and a determined broad—
based effort by the manufacturers to comply with the final stan-
dards, we have concluded that a successful trap oxidizer design can
be optimized within the next 1—1/2 to 2 years.
This brings us to the general issue of lead time. The time
needed from the end of the development phase for a design change to
when that design change can be integrated into mass production can
be dependent on many factors, such as the complexity of the change,
the size of the manufacturer, whether the manufacturer has the
capability to produce the new hardware, etc. We received differing
estimates of production lead time requirements for trap oxidizers.
Volkswagen projected 1 1/2 to 2 years, while Daimler—Benz estimated
3 years (for major engine modifications in general). General
Motors appears to have given two different lead time estimates. In
its prepared statement at the public hearing, it stated that 2 1/2
to 3 years production lead time would be required “after an accep-
table method is defined”, while in its written comment GM claimed
it needed 50 months from “system design selection.” In response to
questions about lead time at the public hearing, GM reaffirmed the
2 1/2 to 3 years estimate. Based on our own understanding of lead
time requirements and the authority of the CM representatives at
the public hearings, we accept the 2 1/2 to 3 years figure as GM’s
best estimate of the leadtime necessary for trap oxidizers, once a
design is selected.
Based on the differing lead time estimates from the inanufac—
turers, and confident that the industry will maximize its efforts
to achieve particulate reductions in the coming years, we have
concluded that the manufacturers could integrate trap oxidizers
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into mass production within 2 to 2—1/2 years after a design is
selected. Thus, combining the 1—1/2 to 2 years development time
and 2 to 2—1/2 years production lead time that we expect to be
necessary, we conclude that trap oxidizers will be feasible on
production vehicles within 4 years. Starting from mid—1979 then,
trap oxidizers can be integrated into production by mid—1983, or in
time for the 1984 model year.
Thus, we agree with the majority of the conunenters that it is
not likely that trap oxidizers will be integrated into production
vehicles by the 1983 model year. However, we forecast that with an
aggressive, good faith effort on the part of the manufacturers,
trap oxidizers can be utilized on production vehicles by the 1984
model year.
D. Recommendation
The 1981 standards should be based on readily available
technology. Turbochargers will not be universally available until
the 1983 model year. Trap oxidizers probably will not be univer-
sally available prior to the 1984 model year. Any standard based
on successful utilization of trap oxidizer technology should be
delayed to the 1984 model year.
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IV. Standards
A. Basis and Nature of Standards
EPA based the levels of the proposed standards on the lowest
particulate levels achievable by the worst light—duty diesel with
respect to particulate emissions. This approach assumes that at
least some manufacturers would be required to utilize the best
available control technology.
Comments
Chrysler —— “The EPA did not follow its own declared procedure
based on reasonableness for setting the particulate standards.
The subsequent analysis not only disregards production variation
and degradation factors but presumes a modified Oldsmobile ‘with
ECR and redesigned chamber and nozzles’... .If they had followed
their stated procedure, the 1981 MY particulate standard would be
at least 1.02 grams per mile (from the Olds 260 CID).”
1ncil on Wage and Price Stability —— “The proposed diesel partic-
ulate standards represent an effort at ‘technology forcing’ by EPA.
We recognize EPA’s legitimate concern in this area. Since partic-
ulate emissions represent a genuine negative externality, it is
Unlikely the vehicle buyers would voluntarily buy control devices,
and therefore it is unlikely that manufacturers would voluntarily
provide them. Further, in the absence of some kind of government
action, the manufacturers would have little incentive to develop
new and improved technology in this area. But, just as there are
drawbacks to too little technology forcing, there are also dangers
in trying to force technology too hard. The rush to meet strin-
gent standards under short deadlines may produce high cost, ineffi-
cient technological solutions, whereas a less rushed development
might lead to lower cost technologies. .. .Alternatively, if the
Standards are considered to be unachievable, development and spread
of the technology may be delayed; given the long lead times and
large financial sums involved in the automobile industry, producers
are unlikely to commit substantial resources to a technology that
may not meet a future set of standards. Yet another alternative is
that there will be last minute delays in the imposition of the
Standards, with heightened costly uncertainties for all parties
Concerned.”
Natural Resources Defense Council —— “In rejecting the option to
base the standard on the lowest particulate level achievable by the
light—duty diesel with respect to particulate emissions, EPA
gave the explanation that ‘it would have prevented all diesels from
meeting the standard except subcompacts and small pick—ups equipped
with small engines. ‘ EPA does not support this statement nor
elaborate upon it. Therefore, we do not see why, given the lead—
time, manufacturers will not be able to meet a tighter standard for
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model year 1983. In any case, the question of whether a standard
should be set so that all manufacturers can meet it should be not
determinative. In International Harvester Company v. Ruckeishaus ,
478 F.2d 615,640 (1973), the Court agreed that an emission standard
should be technology—forcing and further stated: ‘We are inclined
to agree with the Administrator that as long as feasible technology
permits the demand for new passenger automobiles to be generally
met, the basic requirements of the Act would be satisfied, even
though this might occasion fewer models and a more limited choice
of engine types.
Congressman Andrew Maguire —— “The [ 1977 Clean Air Act] passed by
Congress embodied two very important precepts as its cornerstones.
First that the primary purpose of the act was to protect the public
health and second that in so doing, it was deemed appropriate in
some cases to require the use of the best available technology to
control pollution. EPA has used that requirement to set the
standards.... [ The manufacturers] have always had to be pushed,
they have always been behind other manufacturers in the rest of the
world on emission control, on safety, on fuel efficiency. It’s
just an unfortunate fact that the historical record shows they have
to be brought kicking and screaming along with the responsibilities
that they ought to discharge to the larger public interest.”
Analysis
The statutory authority for the diesel particulate regulations
is found in Section 202(a)(3)(A)(iii) of the Clean Air Act, which
provides that:
“The Administrator shall prescribe regulations under paragraph
(1) of this subsection applicable to emissions of particulate
matter from classes or categories of vehicles manufactured during
and after model year 1981 (or during any earlier model year, if
practicable). Such regulations shall contain standards which
reflect the greatest degree of emission reduction achievable
through the application of technology which the Administrator
determines will be available for the model year to which such
standards apply, giving appropriate consideration to the cost of
applying such technology within the period of time available to
manufacturers and to noise, energy, and safety factors associated
with the application of such technology. Such standards shall be
promulgated and shall take effect as expeditiously as practicable
taking into account the period necessary for compliance.”
We agree with Congressman Maguire and the Council on Wage and
Price Stability (CWPS) that this section mandates best available
control technology and, accordingly, technology forcing standards.
Otherwise it is very unlikely that the “greatest degree of emission
reduction achievable” mandate would be met. The CWPS claim that
we may be forcing technology “too hard” is certainly a valid
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concern. And because of the limited leadtime available for the
1981 model year the 1981 standard should be based on technology
that is already readily available. We have already analyzed the
leadtime requirements for trap oxidizers and have concluded that
another entire year is necessary for successful application of this
technology. We are confident that we are not forcing any control
technology too hard or too quickly.
In its comment Chrysler claims that the 1981 standard should
be “at least 1.02” g/mi (0.63 g/km). This appears to be based on
the argument that the 1981 standard should be set at the highest
particulate level that EPA found in its baseline testing of 1979
certification vehicles. This line of reasoning is clearly in
conflict with the letter and spirit of the Clean Air Act quoted
above, and ignores the reality that significant particulate emis-
sion reductions have been achieved since the 1979 certification
vehicles were designed (presumably late 1977). In effect, Chry-
sler’s reasoning would “freeze” the particulate standard forever at
1.02 g/tni (0.63 g/km). It should also be noted that the 1.02 g/mi
(0.63 g/km) figure was the highest particulate level EPA recorded
for the Oldsmobile 260 engine but was not the only value; EPA
recorded levels as low as 0.73 g/mi (0.45 g/km) as well.
The Natural Resources Defense Council (NRDC) argues that EPA
has the statutory authority to set standards based on the lowest
particulate level achievable by the best light—duty diesel vehicle.
Thus, we could set standards that would force some diesel models
Out of production. Reading Section 202(a)(3)(A)(iii) above in
full, with its emphasis on the leadtime necessary for compliance,
and on energy and safety factors, leads us to dismiss this argu-
ment.
B. Particulate/NOx Relationship
The proposed standards were set under the assumption that the
1981 statutory NOx standard of 1.0 g/mi (0.62 g/km) would not be
waived for any diesel manufacturer. EPA recognized that current
NOx control techniques, such as exhaust gas recirculation, tend to
increase particulate emissions.
Comments
Fiat —— “(T]he most effective ways (to reduce NOx emissions], i.e.,
exhaust gas recirculation or retarding injection timing in connec—
tio with the oxidation catalyst, decrease NOx while they increase
particu lates.... [ A]ny future solution for decreasing NOx will
compromise 0.6 gpm particulate emission standards proposed by EPA.
In other words at present a correct approach to particulate limita-
tion must take into account an acceptable level of NOx.”
Ford —— “We believe it is also unreasonable to rely on particulate
iision data obtained from vehicles designed to meet a 2.0 gpm NOx
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standard as being indicative of the particulate control which can
be achieved with vehicles which must also meet a 1.0 gpm NOx
standard.”
General Motors — — “The use of EGR has always resulted in a particu-
late emission increase, and this penalty becomes more severe as
additional EGR is required to lower NOx levels... .Full—size cars
appear to have a double disadvantage in this particulate—NOx trade
off. Full-sized vehicle NOx emissions require the largest percent
reduction, and, in addition, the full—sized cars show the highest
particulate penalties for a given NOx reduction.”
Congressman Dale E. Kildee — — “While I recognize that no applica-
tion for a waiver of the NOx standard has been made yet, I am also
disturbed by what appears to be a prejudgment on the question of a
waiver of the NOx standard. This question of whether a waiver of
the NOx standard will be sought or granted is essential to the
whole issue involved in this rulemaking. . . .In examining the pro-
posed regulations and rulemaking support paper, I am left with the
impression that the Environmental Protection Agency has prejudged
the issue. If so, this would seem to indicate disregard for
congressional intent and the existing law.”
Analysis
EPA has recognized throughout this rulemaking that many of the
technologies currently available to reduce NOx emissions tend to
increase particulate emissions. Although we based our proposed
standards on the assumption that no NOx waiver would be granted, we
did so not, as Congressman Kildee suggests, because we had pre-
judged the issue; rather, we did so because we felt it was neces-
sary to base our analysis on a worst—case scenario for particulate
emissions. To have done otherwise, i.e., to have assumed a NOx
waiver when it might not actually be granted, might have led us to
propose more stringent particulate standards than we did. Thus our
position was based on fairness to the manufacturers.
Data received from the industry in both this rulemaking and
the NOx waiver public hearings have convinced EPA that with the
current state of diesel emission control technology, NOx control
(to 1.0 g/nii, 0.62 glkm) is a more difficult technical problem than
particulate control. Thus, the optimum position is to promulgate
the most stringent particulate levels feasible within NOx con-
straints of 1.5 g/mi (0.93 g/km) in 1981 and 1.0 g/mi (0.62 g/km)
in 1984, and then resolve the NOx waiver issue based on the con-
straint provided by the particulate standards.
C. Deterioration Factor
Comments
— — “To establish the levels of the particulate standards,
the EPA has considered that no major deterioration of the levels
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of the particulates will occur during the useful life of the
vehicle.... For this assumption, the EPA’s judgment was in partic-
ular based upon the fact that ‘part iculates and hydrocarbon emis-
sions follow each other directionally when changes are made in a
given engine’. We believe that an inverse phenomenon may happen
under certain conditions. As far as the deterioration factor is
concerned, we are lacking mileage accumulation results, however, we
have measured on a diesel 504 a level of particulates of 0.62 gram
per mile at about 100,000 miles. Taking into account the estimated
production variation it may be supposed that the deterioration
factor, for this particulate case, is between 1.15 and 1.72. This
result allows to assume that the deterioration factor cannot be
considered as negligible even for a 50,000 miles durability.”
General Motors “Emission development targets must be established
with consideration of deterioration factors... . (T]he available
particulate data on emission tests are inadequate for accurate
determination of particulate deterioration factors. The limited
data indicate generally positive factors ranging from 1.2 to 1.4.”
Analysis
Unfortunately, we received very little data on the effect of
mileage accumulation on particulate emission levels. Our original
assumption of a negligible deterioration factor was based on the
low HC deterioration factors of 1978 certification diesel vehicles
and on the well known stable nature of the compression ignition
engine. The stability of the diesel engine with respect to HC
emissions is reaffirmed by the 1979 certification data; the
average HC deterioration factor was 1.06 (assuming all deteriora-
tion factors less than 1.0 to be 1.0).
We cannot refute Peugeot’s comment that I -IC and particulate
emissions sometimes have an inverse relationship, but we must point
out that this is an atypical claim. It must also be noted that
the data upon which Peugeot relies for this statement shows par-
ticulate to drop only slightly while I-IC emissions rise sharply with
retarded timing. While ac deterioration factors are not perfect
indicators of particulate deterioration factors, they are one gauge
we have to predict particulate deterioration factors. Based on the
very low diesel HC deterioration factors that have been observed,
we expect particulate deterioration factors to be very close to
Unity.
We did receive a small amount of particulate data on vehicles
which had accumulated mileage. Peugeot reported that one of their
504D vehicles emitted 0.62 g/mi (0.39 g/km) particulate at approx—
itnately 100,000 miles. Their own measurements have shown the 504D
to emit between 0.36 and 0.59 g/mi (0.22 and 0.37 g/kin) at low
mileage, thus this vehicle is estimated to have had a deterioration
factor of between 1.05 and 1.72 (rather than the range of 1.15 to
47
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1.72 that Peugeot quoted) over 100,000 miles or between 1.03 and
1.36 over 50,000 miles. It must be emphasized that while certifi-
cation deterioration factors are based on a least—squares regres-
sion of data taken at low mileage, at 50,000 miles, and at regular
intervals in between, the only particulate measurement made on this
vehicle was at 100,000 miles. Thus no data are available for this
vehicle which would actually be used in the calculation of the
deterioration factor, and we have little confidence in the esti-
mated range.
General Motors reported limited particulate durability emis-
sions data. They calculated particulate deterioration factors for
four cars, shown in Table IV—1.
It is rather difficult to draw any conclusions from the data
in Table tV—i. The 1976 Opel was used for particulate trap devel-
opment by GM. The data. used in the deterioration factor calcu-
lation for this vehicle were all gathered as baselines with stan-
dard exhaust systems during this development program except for the
5,000—mile data which were gathered prior to the trap development
program. If the 5,000—mile data were excluded, the particulate
deterioration factor would be very close to 1.0. It should also be
noted that the lowest deterioration factors were for the 5.7—liter
GM engine, while the higher values were for the Opel 2.1—liter
engine that is not sold in the U.S. Finally, particulate data were
reported for one other GM 1980 5.7—liter, 4,500—pound vehicle with
limited mileage accumulation in GM ’s NOx Waiver Request submitted
to EPA in May, 1979. Four emissions tests were performed both at
5,500 and at 19,000 miles on car 86597, two tests with EGR and two
tests without EGR at each mileage. All mileage accumulation was
with EGR. With EGR the particulate emissions dropped from 0.86
g/mi (0.53 g/km) at 5,500 miles to 0.67 g/mi. (0.42 g/km) at 19,000
miles. Without EGR the particulate emissions went from 0.47 g/mi
(0.29 g/km) to 0.42 g/tui. (0.26 g/km). Thus, for car 86597, the
particulate deterioration factor appears to be less than one, both
with and without EGR.
The foregoing analysis of GM’s own durability data indicates
that there is no basis for assuming that deterioration factors for
particulate emissions will be in the range of 1.2 to 1.4. Rather,
GM’s data, along with the low diesel HC deterioration factors and
the stable nature of the compression ignition engine, indicate that
particulate deterioration factors will be very low, most likely in
the 1.0 to 1.1 range.
D. Design Targets
Comments
Peugeot —— “If taking into account the today 504 Diesel the results
made at Peugeot facilities on some vehicles with low mileage, set
48
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Table IV—1
GM Particulate Deterioration Factors
Car/Displacement
Test
Particulate DF
80 Olds Delta 88/5.7 L
80 Olds Delta 88/5.7 L + EGR
78 Opel/2.l L + EGR
76 Opel/2.l L
50 K AMA
27.6 K AMA
50 K AMA
Trap Development
Baseline Tests
1.03
0.66
1.26
1.53
49
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the dispersion range at 0.36/0.59 gram per mile. Results recorded
by the EPA on such a model varies according to our knowledge, from
0.29 gram per mile to 0.50 gram per mile. If we take into consid-
eration all these results on a limited number of vehicles the mass
production variation is probably higher than 50% (+25%) of the
average measured value.”
General Motors —— “Emission development targets must be established
with consideration of... engine—to—engine variability and repeata-
bility of emission measurements on individual vehicles.” GM
estimated their car—to—car variability to be i-30% with respect to
particulate emissions.
Volkswagen —— “It is our impression that EPA has not considered the
absolutely necessary safety margin between any standard and the
certification level. . . .Traditionally, the safety margin has been 40
to 50 percent in order to account for prototype—to—production
slippage, statistical spreads and systematic measurement devia—
t ions.”
Analysis
We understand the necessity of designing research prototype
vehicles to an emission level below that of the standard which
production vehicles must ultimately comply with. But, the safety
margins claimed to be necessary by the manufacturers are over-
stated.
There will be a certain “slippage” between the particulate
levels achieved by research prototype vehicles and the levels a
manufacturer could confidently expect to meet with certification
vehicles. Based on our experience with the certification process,
and absent any data with regard to particulate emissions, this
slippage should be small, likely on the order of 10 percent.
The manufacturers’ concerns over production car—to—car varia-
bility are misplaced, however. Although there no doubt will be
production variability with respect to particulate emissions, the
statistical sampling program used in Selective Enforcement Auditing
(SEA) acconunodates such variability.
Test—to—test variability, which can be considered a part
of car—to—car variability, also does not seem to be a major prob—
lem. EPA has found diesel particulate test—to—test variability to
be less than 5 percent and GM has reported similar results. We
expect this variability to improve even more in the future as the
industry accumulates more experience with the test procedure.
E. Proposed 1981 Standard
EPA proposed a standard of 0.60 g/nti (0.37 g/km) beginning
with the 1981 model year for all light—duty diesel vehicles.
50
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Comments
Peugeot —— “It is Peugeot’s point of view that to meet 0.6 gpm
parti i1ates level, the NOx standard should be relaxed to 1.5
gpm.”
uncii on Wage and Price Stability — — “We recommend that the 1981
Standard be promulgated only if EPA is prepared to grant the
appropriate waivers for nitrogen oxide emissions in 1981—1984.”
Daimler—Benz —— “At a 1.5 NOx standard, Daimler—Benz believes that
there is a reasonable chance that a particulate matter standard of
0.6 for model year 1981 can be achieved and maintained for 50,000
miles.”
Fiat “If EPA were to waive the 1981 Federal NOx standard of 1.0
gpm, raising it to at least 1.5 gpm, the manufacturers could
concentrate their effort to try, with a probability of success, to
obtain reductions of particulates equivalent to the 0.6 gpm stand-
ard.”
—— “EPA should promptly promulgate a 1981 and subsequent model
year particulate standard which represents the greatest control
achievable without use of control devices or technologies whose
effect on unregulated pollutants is yet to be investigated. In the
case of passenger cars, we believe this level to be approximately 1
gpm.”
General Motors —— “ [ T]he technically achievable standard for
1981 would be 1.0 gpm particulates based upon receiving a waiver to
1.5 gpm NOx.”
Volvo —— “Volvo believes that the granting of a waiver.. .to 1.5 gpm
NOx will be essential (along with a] particulate standard of 1.0
gpm in 1981.”
ysler —— “Chrysler suggests that the standard be set at 1.0 gpm
for 1981.”
kswagen —— “ [ A]ssuming that EPA grants our NOx waiver request, a
reasonable schedule for n eting a 0.6 gpm particulate standard
Would be model year 1982.”
partment of Energy —— “A particulate standard higher than 0.8 gpm
Will be required for the 1981 model year....With a 1.5 gpm NOx
waiver, a 0.6 gpm particulate emission level is technically achiev-
able by 1982.”
Analysis
As discussed earlier, we no longer consider turbochargers to
51
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be universally available for the 1981 model year. Despite the fact
that it has been shown that turbochargers can substantially reduce
particulate emission levels, we cannot rely on them as a basis for
the 1981 standard. Nevertheless, the industry should be able to
comply with a final standard of 0.6 glmi (0.37 g/km) particulate in
1981. Our position is based on three points. First, as has
already been discussed, the manufacturers have made much more
progress in reducing particulate emissions through engine modifica-
tions than EPA had projected. Second, we now consider it appro-
priate to determine the most stringent particulate level achievable
within the 1.0 to 1.5 g/mi (0.62 to 0.93 g/km) NOx framework,
rather than being constrained by the 1.0 g/tni. (0.62 g/km) no—waiver
scenario. Finally, and most importantly, the manufacturer’s own
data show that they can comply with a 0.6 g/mi (0.37 g/km) particu-
late standard at a NOx level of 1.5 g/mi (0.93 g/km) or less.
Table tV—2 summarizes the most promising data received from each
of the manufacturers who reported particulate/NOx data from their
own research programs.
As the comments indicated, Mercedes, Peugeot, and Fiat all
believe that it is quite probable that they can meet 0.6 g/mi (0.37
glkm) particulate at a NOx level of 1.5 g/mi (0.93 g/km). Their
data in Table IV—2 supports their positions. Thus, these manufac-
turers’ positions need no further analysis.
Volkswagen has admitted that their two most popular models,
the Rabbit and the Dasher, would have no problem meeting the 0.6
g/mi. (0.37 g/ktn) standard. They claim that their Audi 5000D cannot
meet 0.6 g/mi (0.37 g/km) until the 1982 model year. As Table IV—2
shows, VW reported typical Audi 5000D emissions of 0.65 gfmi (0.40
g/km) particulate and 1.73 g/mi (1.08 g/km) NOx for naturally—
aspirated production vehicles and 0.58 g/mi (0.36 g/kin) particulate
and 1.87 g/mi. (1.16 g/km) NOx for turbocharged prototype vehicles.
Thus, the Audi appears to have a NOx problem as well as a particu-
late problem. Because of its relatively small size (2.0—liter
engine, 3,000—pound vehicle) we were surprised at VW’s assertion
that it could not meet 0.6 g/mi (0.37 g/km) particulate and 1.5
g/mi (0.93 g/km) NOx and have examined the situation further.
First of all, the 1979 Audi 5000D durability vehicle emitted 1.30
g/mi (0.81 g/km) NOx and thus we would not expect 1.5 g/mi (0.93
g/km) NOx in 1981 to be difficult to achieve. Secondly, since the
data above are on production vehicles, we are confident that
particulate and NOx improvements have been achieved through engine
modifications since the data were collected. Thirdly, we have
found that Volkswagen seems to get consistently higher particulate
measurements at their German laboratory when compared to EPA test
results in Ann Arbor. Table IV—3 gives the comparisons that have
led us to this conclusion. In every case Volkswagen measured
significantly higher particulate levels, from 25 to 43 percent
higher. The EPA Audi value was based on two tests of one vehicle,
while the VW Audi value was an average of eight production ye—
52
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Table IV—2
Best Particulate/NOx Data as Reported by Manufacturers
Manufacturer Engine Vehicle Particulate NOx
and Model Size (1) Weight (ib) cgfmi) ( g/km) ( g [ mi) ( g/km) Comments
Daimler—Benz
240D 2.4 3,500 0.40 0.25 1.47 0.91 “1981 Projections” w/ECR, 2 tests
300D 3.0 3,875 0.30 0.19 1.31 0.81 “1981 Projections” w/EGR, 2 tests
300SD 3.0 4,000 0.47 0.29 1.21 0.75 “1981 Projections” w/EGR, TC, 2 tests
Peugeot
504D 2.3 3,500 0.49 0.30 1.51 0.94 Prototype
504D 2.3 3,500 0.44 0.27 1.08 0.67 Prototype w/EGR, TC
Volkswagen
Rabbit 1.5 2,250 0.33 0.21 1.07 0.67 Seven Production Vehicles
Dasher 1.5 2,500 0.42 0.26 1.46 0.91 Ten Production Vehicles
Audi 5000D 2.0 3,000 0.65 0.40 1.73 1.08 Eight Production Vehicles
Audi 5000D 2.0 3,000 0.58 0.36 1.87 1.16 Three Prototypes v/TC
Fiat 2.4 3,000 0.53 0.33 1.19 0.74 Prototype w/EGR, TC
General Motors
“260” 4.3 4,000 0.27 0.17 1.01 0.63 Prototype 72204 w/EGR, 3 tests
“260” 4.3 4,000 0.41 0.25 1.06 0.66 Prototype 93516 w/EGR, 4 tests
“260” 4.3 4,000 0.50 0.31 1.29 0.80 Prototype 93513 w/ECR, 2 tests
“260” 4.3 4,000 0.56 0.35 1.10 0.68 Prototype 93514 v/EGR, 2 tests
“350” 5.7 4,500 0.43 0.27 1.20 0.75 Prototype 96558 w/EGR, inter-
polated from CM graph
“350” 5.7 4,500 0.36 0.22 1.15 0.71 Prototype 96589 w/EGR, 3 tests (2/79)
“350” 5.7 4,500 0.39 0.24 1.00 0.62 Prototype 96589 w/EGR, 2 tests (6/79)
“350” 5.7 4,500 0.56 0.35 1.10 0.68 Prototype 86634 w/ECR, 2 tests
8,000 miles
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Table IV—3
EPA/Volkswagen Particulate Measurement Comparisons
EPA Particulate VW Particulate
Result Result
Model ( glmi) ( g/km) Cg/xni) jkm) Difference
79 Rabbit 0.23 0.14 0.33 0.21 + 43%
79 Dasher 0.32 0.20 0.42 0.26 + 31%
79 Audi 5000D 0.46 0.29 0.65 0.40 + 41%
DOT Special 0.20 0.12 0.25 0.16 + 25%
Build Rabbit
54
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hides, yet the EPA value was lower than all eight of the VW
values. Thus, based on its small size, the 1979 durability ve-
hicle, the expected particulate and NOx reductions achieved
through engine modifications, and the significantly lower particu-
late values that EPA has obtained for VW vehicles, it is antici-
pated that the Audi 5000D can meet a 0.6 g/mi. (0.37 g/km) particu-
late standard in 1981 at a NOx level of 1.5 g/mi (0.93 g/km) or
less. Should the Audi 5000D not be able to meet the particulate
and NOx standards, while much larger engines and vehicles do, we
could only conclude that the Audi 5000D is an unusually high
particulate emitter and should not be marketed in the U.S. until
the problem is remedied.
General Motors is undeniably in a more difficult technical
position, due to its larger engines (5.7 and 4.3 liters) and
heavier vehicles (4,500 and 4,000 pounds). GM’s particulate
reduction program has produced promising results, however, and the
data we received in its comment and in its NOx waiver request lead
us to the conclusion that GM can meet 0.6 g/mi (0.37 g/kni) particu-
late at a NOx level of 1.5 g/mi (0.93 g/km).
Table IV—2 gives the most promising particulate/NOx data for
the CM 4,000 and 4,500—pound diesel vehicles. GM considers the
5.7—liter, 4,500—pound vehicle to be its worst—case vehicle for
particulate and NOx emissions. As of June 19, GM still had not
selected a “prime system” for its 1981 5.7—liter engine family.
Prototype car 96558 was one design being considered. GM reported
only four particulate data points for car 96558, two tests without
EGR (low particulate emissions) and two tests with a relatively
high ECR rate (low NOx emissions); CM averaged each pair of tests
and plotted the data in Figure IV—1 (Figure II.C.29 in GM’s NOx
Waiver Application). The parabola drawn by GM represents its best
estimate of the part iculate/NOx levels that would be expected for
car 96558 at varying EGR rates. From Figure IV—1, it can be
determined that car 96558 would emit approximately 0.43 g/ini (0.27
g/kin) particulate with a NOx level of 1.2 g/mi (0.75 g/km). Also
shown on Figure IV—1 are four tests on car 96589 at approximately
0.5 g/mi (0.31 g/km) particulate and 1.2 g/mi (0.75 g/km) NOx. Not
shown on the GM graph, but reported on the individual data sheets
in the GM NOx Waiver submissions, are two sets of baseline tests
when car 96589 was being used for developmental work with EGR, a
four—speed transmission, and a torque converter clutch (TCC).
Three tests with 96589 in February 1979, with a three—speed trans-
mission and without the TCC, resulted in average emissions of 0.36
g/mi (0.22 g/km) particulate and 1.15 g/mi (0.71 g/km) NOx. In
June 1979, two more baseline tests produced average emissions of
0.39 g/mi (0.24 g/km) particulate and 1.00 g/mi (0.62 g/km) NOx.
The final 5.7—liter, 4,500—pound vehicle listed in Table IV—2 is
car 86634. The only emissions results submitted to EPA for this
vehicle were four tests performed after it had accumulated 8,000
miles. The two tests with EGR gave 0.56 g/mi (0.35 g/km) particu—
55
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—1•
FIGURE IV
56
[ _______________________ —
GN Figure ILC.29 — :
:
:
• H
•.
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—
lii _
• :TIii j
•
l
—__________________ — I
:
I__i
\
I
- , - I
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/ : H
- I
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• • ..• I ,•
I • I • — — — _, , .
— I I •
.
I I •
I . .1
I. I
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.
I
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—;————•——•———•—————
—
•
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- I I •••• I • •
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*From General Motors Application for Waiver of the 1981—1954
NOx Emission Standards for Light—Duty Diesel Engines, May 1979
-------
late and 1.10 g/mi (0.68 g/kin) NOx. The non—EGR tests gave predic-
tably higher NOx and lower particulate emissions. These data have
convinced EPA that the GM 5.7—liter, 4,500—pound vehicle can meet
the 0.6 glmi (0.37 g/km) particulate standard in 1981, taking into
account the necessary safety margin for prototype—to—production
slippage, variability, and deterioration factor. In addition, it
should be noted that all the particulate data above were at NOx
levels of 1.0 to 1.2 g/mi (0.62 to 0.75 glkm) and thus the EGR
rates could possibly be lessened, if necessary, to lower the
particulate levels even more. Since diesel NOx deterioration
factors are typically 1.0, this would be quite possible.
Data from four 4.3—liter, 4,000—pound CM diesel prototypes are
also shown in Table IV—2. Three of the four prototypes were of the
very same design, with car 93514 “a slightly different technology.”
Car 72204 emitted just 0.27 g/mi (0.17 g/kin) particulate and 1.01
g/mi (0.63 g/km) NOx (average of 3 tests), but GM stated that these
very low emissions have not been repeatable. The two other proto-
types of the same design also gave promising results. Car 93516
emitted 0.41 g/mi (0.25 g/ktn) particulate and 1.06 g/mi (0.66 g/km)
NOx (average of 4 tests) and car 93513 emitted 0.50 g/mi (0.31
g/km) particulate and 1.29 g/mi (0.80 g/km) NOx (average of 2
tests). Car 93514 emitted 0.56 g/mi (0.35 g/km) particulate and
1.10 g/mi (0.68 g/km) NOx (average of 2 tests). Thus, we have
three prototypes of the same design and one vehicle of slightly
different design which all meet the particulate standard at low NOx
levels. We are convinced that the 4.3—liter, 4,000—pound GM
vehicle can meet the 0.6 g/mi (0.37 g/km) particulate standard in
1981.
GM’s primary concern with the design of these prototypes is
the durability of the engines. This is because of the greater oil
contamination apparently due to the greater EGR rates. As men-
tioned above, the EGR rates of these prototypes might be slightly
higher than necessary, and might be lowered, thus lessening any
durability concerns. In any case, EGR is used for NOx control,
and will be utilized on GM’s diesels regardless of the particulate
standard. Thus, any durability problems will not be due to partic-
ulate control.
While GM was adamant in its comments to the particulate NPRM
that it could only meet 1.0 g/mi (0.62 g/km) particulate and 1.5
g/mi. (0.93 g/km) NOx in 1981, it did not make any such claim in its
NOx waiver request. Of interest was a section on the effect of the
NOx waiver on public health. In that section CM performed a “worst
case” air quality analysis and had to select emission rates. To
quote:
“The emission rates assumed for this analysis are: 1.5 gpm
NOx (20 percent of which is NO 2 ), 0.6 gpm particulate if
the waiver is granted, and, 1.0 gpm NOx (10 percent of which
57
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is NO 2 ), 1.0 gpm particulate if EPA denies the waiver. These
emission values agree with observed data discussed later in
this section and also agree with comments by various manufac-
turers at the recent EPA hearing on particulate standards.”
it is not clear what GM meant by this statement, but it does lend
credence to our conclusion that GM can meet 0.6 g/mi (0.37 g/km)
particulate in 1981.
Neither International, Ford, Chrysler, Volvo, BMW, ANC, nor
Toyota reported any original data on their own diesel engines.
International is the only one of these manufacturers currently
marketing a light—duty diesel in the U.S.; its a light—duty truck
and will be considered later in this section.
In summary, we conclude that every light—duty diesel manufac-
turer can taeet a 1981 particulate standard of 0.6 g/mi (0.37 g/ktn)
at NOx levels of 1.5 g/mi (0.93 g/km) or less , utilizing readily
available control technology.
F. Proposed 1983 Standard
EPA proposed a standard of 0.20 g/mi (0.12 g/ktn) beginning
with the 1983 model year for all light—duty diesel vehicles.
Comments
Department of Energy —— “EPA should not set a more stringent
standard requiring aftertreatment control devices until basic
questions concerning the effectiveness, safety, and durability of
aftertreatment devices are answered... .Etnission levels of 0.5 gpm
particulate and 1.3 gpm NOx represent realistic goals for 1983....
Research goals of 0.3 gpm particulate and 1.0 gpm NOx for 1985
should be established.”
Volkswagen —— “ [ W]e recommend that a decision to set a standard
requiring a trap oxidizer be postponed until 1980 or 1981....
lAin ultimate standard of 0.4 gpm could be met not sooner than
model year 1985.”
Natural Resources Defense Council —— “ [ Wie do not see why, given
the leadtime, manufacturers will not be able to meet a tighter
standard for model year 1983.”
Peugeot —— “ [ Wie propose the postponement of this stringent 1983
particulate standard until it is demonstrated that the exhaust
post treatment in view to reduce the particulates, is feasible in
production.”
Toyota —— “Set a standard for 1983 and subsequent model years of
0.8 gpm particulates. Delay the decision of whether or not to
58
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set a more stringent standard to the time when the need for such
becomes evident and the technology to meet a lower particulate
emissions level simultaneously with the 1.0 gpm NOx requirement is
available.”
Department of Commerce ——“We question the plan for more stringent
standards in 1983.... [ N]ew engineering developments will enable a
stricter standard to be met by the middle or late 1980s.”
Council on Wage and Price Stability —— “ [ T]he 1983 standard may be
overly stringent... .Since the National Ambient Air Quality Standard
for particulates is currently under review, since the carcinogenic
properties of diesel particulates are still uncertain, and since
the proper role of adjustments in the composition of diesel fuel to
control particulates is still unclear, this does not appear to be
the proper time to be promulgating a very stringent standard for
1983.”
Volvo —— “Particulate standard of.. .0.4 gpm in 1985 [ is] proposed
as the lowest feasible level.”
General Motors —— “Our goal would be to reduce particulate levels
by over 50% by 1985 [ to 0.5 gpm], while at the same time reducing
NOx to a 1.0 gpm standard... .Any lower standard will most probably
eliminate diesels from heavier vehicles.”
Daimler—Benz —— “At a 1.5 NOx standard Daimler—Benz believes that
it is not possible to achieve the proposed 0.2 gpm particulate
matter standard for 1983.”
Analysis
EPA has consistently maintained that a 0.2 g/mi (0.12 g/km)
particulate standard could be universally met only by the utili-
zation of trap oxidizers with approximately 67 percent efficiency
over the lifetime of the vehicle. Since we have concluded else-
where in this analysis that successful trap oxidizer application is
not expected prior to the 1984 model year, the 0.2 g/mi (0.12 glkm)
standard should be delayed for one year until 1984.
Another factor that must be considered is the statutory 1.0
g/mi (0.62 g/km) NOx standard in 1985. EPA does not expect the 0.2
g/mi (0.12 g/km) particulate and 1.0 g/tni (0.62 g/km) NOx standards
to force any diesel models out of production. It is true that at
this time the primary NOx control technique, EGR, significantly
increases particulate emissions. But EPA is convinced that as the
EGR/particulate relationship becomes better understood, the dele-
terious effect of EGR on particulate levels will be lessened. In
addition, it is expected that other NOx control techniques will be
developed which will not necessarily increase particulate emis-
sions; it is certainly plausible that a NOx control technique might
reduce particulate emissions.
59
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EPA’s technical staff also expects additional particulate
reductions in the 1981 to 1985 time frame other than that due to
the trap oxidizer. As concluded earlier, it is extremely unlikely
that the many engine parameters that can affect particulate emis-
sions have all been discovered and optimized in the two years since
particulate control development work began. Should additional
manufacturers decide to turbocharge their engines, it would enable
them to utilize smaller engines with reduced particulate levels,
while retaining comparable performance. Finally, with the Cor-
porate Average Fuel Economy standards increasing annually until
1985, and with other emission standards decreasing, EPA expects
that many manufacturers will continue to downsize their vehicles in
order to comply with the impending regulations. All these factors
should contribute to lower particulate levels by 1985, and EPA has
determined that all diesel models will be able to comply with 0.2
g/mi (0.12 g/km) particulate and 1.0 g/mi (0.62 g/km) NOx standards
by 1985.
We cannot accept the recommendations of those cotmnenters who
held that any more stringent standard (than the 1981 standard)
should await further research, or of those who recommended a much
lower or much—delayed “second step” standard. As was thoroughly
discussed in section A, the Clean Air Act mandated “the greatest
degree of emission reduction achievable” which implies use of the
best available control technology. Past experience has shown that
only through the application of technology forcing standards will
that mandated particulate reduction occur. In the previous two
sections, we analyzed trap oxidizer development and concluded that
trap oxidizers could be available for the 1984 model year. Should
the industry aggressively pursue trap oxidizer development, but
fail, it would be possible for the industry to petition EPA for a
possible relaxation of the standards.
G. Light—Duty Trucks
EPA’s position in the NPRN was that diesel—powered light—duty
trucks (LDTs) should be required to meet the same particulate
emission level as diesel—powered light—duty vehicles (LDVs). EPA
believed that if one category of vehicles was regulated more
stringently than another, with both categories using the same
diesel engine, this would create a bias in favor of the less
stringently regulated vehicles.
Comments
General Motors — — “Only a limited amount of emission data currently
exists relating to vehicles heavier than 4,500—pounds inertia
weight. The following are FTP data obtained from two cars,
both tested at three different inertia weights and all at 14 hp.
The first car shown was a 1980 preproduction vehicle with modified
injection timing.
60
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Particulates
Inertia Weight 3,500 4,500 5,500
Vehicle Number
89589 .30 .35 .46
78504 .65 .7]. .81
Emission data for the Oldsmobile 350 installed in heavier trucks is
also fragmentary at this time; however, the following data was
obtained for one vehicle of 8,500 pounds GVW and tested at 20 hp.
Inertia Weight Particulates
5,000 pounds .58
5,500 pounds .76
These data again demonstrate the relationship of particulates to
inertia weight.”
International Harvester — — “I.H. vehemently objects to the Adinini—
strator’s classification of trucks over 6,000 pounds as light—duty
vehicles for the purpose of establishing one connnon standard for
particulate control. This classification is erroneous and contrary
to the intent of Congress. It is also obvious from a review of the
Clean Air Act Amendments that Congress desired to treat light—duty
vehicles and heavy—duty vehicles differently. EPA’s own regula-
tions, as well as NHTSA’s, account for this difference by estab-
lishing different roadload horsepower (RLHP) and inertia weight
(1w) requirements as well as the application of separate exhaust
emissions and fuel economy standàrds....In promulgating regulations
concerning trucks between 6,000—8,500 pounds, the Administrator has
no alternative other than to follow the parameters set forth by
Congress for heavy—duty vehicles, including the promulgation of a
non—conformance penalty.”
Daimler—Benz —— “Daimler—Benz undertook a series of additional
tests which indicate that EPA should give more consideration than
it has up to now to the impact the inertia weight of a vehicle has
on particulate matter and NOx emissions....A 300D vehicle with a
naturally aspirated engine which represented an NOx concept of 1.5
gpm was tested under various inertia weight settings....(C]on—
cerning NOx emissions, a clear and distinct increase was found each
time inertia weight and roadload settings were increased. . .con-
cerning particulate matter emissions, increases in inertia weight
settings resulted in substantial increases in particulate emis-
sions.”
Chrysler —— ‘ EPA states that increased inertia weight in diesel
tests does not increase particulate emissions. Chrysler data
refutes this point. Chrysler has found that increasing inertia
61
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weight from 2,500 to 4,500 pounds causes diesel particulate emis-
sions to increase by approximately 33%. Assuming this trend
continues to 8,500 pounds, it will be considerably more difficult
for trucks than it is for cars to meet the proposed particulate
emissions standards.”
Council on Wage and Price Stability —— “ [ I]t is clear that larger
vehicles require larger engines (especially if the vehicles are
expected to carry heavy loads) and that the larger engines general-
ly emit more particulates and have more difficulty in achieving any
given standard. For example, for the 11 diesel vehicles whose
emissions are reported in the Preamble to the NPRN, the simple
correlation coefficient between particulate emissions and cubic
inches of displacement is + 0.72. Since light—duty trucks have
load—carrying roles to play and since they require bigger engines,
they should have a separate standard. The only offsetting factor
is that, for 1981 and 1982, light—duty trucks will have less
stringent NOx standards of 2.3 g/mi, which should make particulate
control less difficult. The NOx standard may be tightened in
1983.”
Analysis
The LDT particulate standards proposed in the NPRM were the
same as those proposed for LDVs. Absolute technical justification
for a separate LDT standard was not available when the NPRM was
published. Data which EPA had were contradictory and inconclusive.
In the comments we received some data on the effects of
inertia weight and road load considerations on LDT diesel particu-
late emissions. All the EPA and industry data are plotted in
Figures IV—2 (road load) and IV—3 (inertia weight).
As can be seen in Figure IV—2, there is only a very slight
effect of road load on particulate emissions. At most, the higher
road load settings of LDTs might account for a few percent increase
in particulate levels.
From Figure IV—3, however, it is apparent that the inertia
weight setting of a LDT does have an effect on its particulate
emission level.
In setting the LDT gaseous standards for the 1979 model year,
EPA extrapolated available data from 5,500 pounds inertia weight
(1w) to represent the heaviest “typical” LDV test 1W to 6,500
pounds 1W which represented the heaviest “typical” LDT test 1W.
Applying these same guidelines to the GM data (Vehicles #89589 and
#78504) and the EPA data on a Dodge truck (shown in Figure 1V3)
resulted in the following increases in particulate:
62
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FIGtJBE IV-2
PARTICUlATE EMISSIONS AS A FUNCTION OF ROADLOAD
flP DRIVING CYCLE
LO
0
OPEL 21001) I O0O LBS • 1W TRUCK 50O LBS • 1W
OPEL 21001) 3000 LBS. 1W —X—
OPEL 21001) 2000 LBS. 1W
DODGE TR1X K 1 5O0LBS . 1W
— — L — -- - - - —
— — —
MERCEDES BENZ 300D 0 3000 LBS • 1W
1 000 LBS. 1W
.3
.2
.1
0.0
0.0 2 14 6 8 10 12 ih 16 18 20 22 214
ROADLOAD IN HORSEPOWER
-------
FIQJRE IV-3
PARTICU lATE EMISSIONS AS A FUNCTION OF INERTIA WEIGHT
FTP IRIVING CYCLE
1.0
.9
OLDSMOBILE 3 OD INSTALLED
IN LD TRUCK @ 20 HP
‘p
z
ON VEHICLE #78SO1 @ ]1 HP
DODGE TRUCK ( ]Ji & 20 H?
0
OPEL 2100D @) -3.2 HP
.6
C ,)
ESTIMATED
‘p
-p
NIRCED& BENZ 300D @ 12.8 HP
‘p ‘p
0
-4
.3 GM VEHICLE # 89589 @ ]J HP
.2
.3.
0.0 - S -
0.0 1000 2000 3000 liooo 5000 6ooo 7000
INERTIA kIEIGHT IN POUNDS
-------
Increase in Particulate
From 5,500 pounds 1W
Vehicle to 6,500 pounds 1W
CM #89589 19%
GM #78504 10%
Dodge Truck 18%
Average 16%
Recognizing that vehicle weights and hence test IWs are
decreasing, and to be consistent with existing test IWs, a more
current comparison would be between 4,500 pounds 1W (current
heaviest “typical” LDV) and 5,500 pounds 1W (current heaviest
“typical” LDT). This analysis of the data in Figure IV—3 results
in the following increases in particulate:
Increase in Particulate
From 4,500 pounds 1W
Vehicle to 5,500 pounds 1W
GM #89589 22%
CM #78504 11%
Dodge Truck 22%
Average 18%
In the above cases, the increases are 16 percent and 18
percent, respectively. These values are in very good agreement
with the Chrysler comment in which Chrysler claimed there was an
approximate 17% increase in particulate emissions for a 1,000
pounds 1W increase (or 33% for a 2,000 pound 1W increase).
The GM Oldsmobile 350 data was considered to be non—typical
because of the extreme slope as compared with the other data, and
therefore was not analyzed. Further, GM labeled this data as
“fragmentary.” Similarly, the Opel (Ricardo) data and the Mercedes
(Daimler—Benz) data were not considered because these did not
represent the “worst case” situation.
Thus, the data clearly indicate the need to take the increased
inertia weight settings of LDTs into consideration. The above data
indicate that the combined effect of inertia weight and road
load settings appears to be approximately 20 percent. If all other
considerations were equal, we would recommend diesel particulate
standards for LDTs which would be 20 percent greater than the LDV
diesel particulate standards.
As the CWPS pointed out, however, one other factor must be
considered. Diesel LDTs will only have to meet a NOx standard of
2.3 g/mi (1.43 g/km) until model year 1985 when a reduction is
65
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mandated by the Clean Air Act for trucks having GVWs over 6,000
pounds. Diesel LDVs will be required to meet a NOx level in the
range of 1.0 to 1.5 g/mi. (0.62 to 0.93 g/km), depending on the NOx
waiver decision, until 1985 when the Clean Air Act mandates a 1.0
g/mi (0.62 g/km) NOx standard. Even assuming the maximum NOx
waiver for diesel LDVs to 1.5 g/mi (0.93 g/km), diesel LDTs will
have a NOx standard 53 percent greater than the diesel LDV NOx
standard for model years 1981 to 1984. Not only does this much
larger NOx level account for the greater NOx emissions (likely
approximately 20 to 30 percent) that would be expected from LDTs,
but because of the relationship between NOx and particulate emis-
sions, it also can allow for the 20 percent higher particulate
emissions that would otherwise be expected due to the greater
inertia weights of LDTs. For example, it is unlikely that any
diesel LDT would need much EGR in order to meet a NOx standard of
2.3 g/mi (1.43 g/krn). These trucks would emit less particulate
than they would if heavy EGR were required to meet a lower NOx
level. For this reason LDTs should be able to meet the 0.60 g/mi
(0.37 g/km) particulate standard in model years 1981 to 1983.
Two factors change this situation in 1985. First, as a result
of the statutory requirement for a 75 percent NOx reduction from
HDVs, the LDT NOx standard is expected to drop to a stringency
level much nearer to the LDV statutory NOx level of 1.0 g/mi (0.62
g/km). The “cushion” that now exists for LDT NOx control would
disappear. Based on the analysis above, the particulate standard
for LDTs should be 20 percent greater (all other things being
equal) than the LDV standard due primarily to the greater inertia
weight settings of LDTs. Secondly, the expected trends in down-
sizing and the use of smaller engines in LDVs will likely not take
place as rapidly with LDTs. The EPA technical staff estimates that
this discrepancy justifies an additional 10 percent particulate
cushion for LDTs. Thus, we recommend that the 1984 LDT particulate
standard be 30 percent greater than the 1984 LDV particulate
standard and set at 0.26 g/mi (0.16 g/kni). Because the NOx LDV/LDT
discrepancy will still be in effect in 1984, it would be possible
to set the 1984 LDT particulate standard at 0.20 g/mi (0.12 g/km)
and raise it to 0.26 g/mi. (0.16 g/km) in 1985. But for simplicity,
we recommend the 0.26 g/nii (0.16 g/km) standard be promulgated for
1984 and later model years.
Thus, we recommend that LDT diesel particulate standards be
set at 0.60 g/mi (0.37 g/km) in 1981 and 0.26 g/mi (0.16 g/km) in
1984.
H. Additional Standard
Comments
Citizens for Clean Air — — “We question whether an ultimate standard
of 0.2 gpm will adequately protect public health in subsequent
66
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years when diesel powered light—duty vehicles could become a
significant fraction of the national fleet. . . .The Agency [ should]
establish a target particulate emission standard of 0.1 gpm to take
effect by 1990.”
Natural Resources Defense Council —— “NRDC recommends that an
additional target particulate emission standard be adopted for
model year 1990. [ S]uch a standard is necessary in order to
protect public health and the environment from emissions arising
from a growing diesel—powered vehicle fleet.”
Analysis
Both of the commenters support a “third—step” diesel particu-
late standard in 1990. EPA does not rule out such a possibility.
But there is no justification for setting a standard eleven years
in advance when it is likely that in the interim research will
justify either a more or a less stringent standard than the one
that could be suggested at this time. It is well known that EPA is
presently carrying out a comprehensive diesel health effects
research program. Having maximized the protection of the environ-
ment and public health within the Clean Air Act mandate, any more
stringent particulate standard will have to be justified either by
results of research showing that diesel particulate is a more
significant health threat than just as a contributor to total
suspended particulate emissions or by a finding that the more
stringent standard is technologically feasible. Neither of these
justifications is possible at this time.
I. Recommendation
Based on the preceding analyses, EPA should promulgate a final
diesel particulate standard of 0.60 g/mi (0.37 g/km) in 1981 for
light—duty vehicles and light—duty trucks. For 1984, EPA should
promulgate final standards of 0.20 g/mi (0.12 g/km) for light—duty
vehicles and 0.26 g/mi (0.16 g/km) for light—duty trucks.
67
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V. Economic Impact
All comments dealing with costs, economic methods, or cost—
effectiveness will be considered in this section.
A. Trap—Oxidizer
Comments
BMW —— estimated (“very approximately due to their lack of exper-
ience in the area”) that a trap—oxidizer would cost $350.
Chrysler —— claimed that EPA had underestimated the cost of a
trap—oxidizer.
General Motors —— estimated that a trap—oxidizer would cost $470—
610 depending on the size of the engine. They also stated that:
(1) EPA had failed to account for the cost of thermocouples,
sensors, a throttle body and actuator, and mounting provisions, (2)
the muffler would still be needed, (3) the electronic control unit
would cost twice EPA’s estimate, and (4) two traps would be needed
for their largest engines.
Analysis
EPA estimated the average cost of a trap—oxidizer to be
$114—$157 (1978 dollars). This cost included $70—86 for the trap
itself, $24—51 for port liners and an insulated exhaust pipe and
$58 for electronic oxidation control. A $15 credit was taken
because the need for either the muffler or resonator could be
eliminated. Also, it was believed that the exhaust gas recircu—
lation systems used to meet the 1981 NOx standard would also
require the electronic control unit ($45) which was included in the
electronic oxidation control above. Thus, the cost of the unit was
split between particulate and NOx control. Last, the assumed
production was 820,000 (V—8), 300,000 (V—6), and 500,000 (1—4).
Before addressing the manufacturers’ specific comments, the
original EPA cost estimates will be revised using: 1) updated
production estimates, 2) a more detailed cost methodology, and 3)
revised projections of the necessary hardware items comprising a
trap—oxidizer system. If manufacturers’ comments address any of
the specific items contained in these revisions they will be
considered at that time. Otherwise, these comments will be con-
sidered after EPA’s cost estimates have been revised.
Because the costs of trap—oxidizers will depend on the produc-
tion volume expected, it will be necessary to make adjustments to
the above assumed production figures before calculating the cost of
each item in the system. The first step in this analysis will be
to estimate light—duty diesel production volumes between 1984 and
68
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1988. This five—year period was chosen because it will correspond
with the period used to calculate the aggregate cost of the 1984
standard, which will be performed in the Regulatory Analysis.
Both the overall light—duty diesel production and the break-
down by manufacturer is needed. These can be found in Section I,
Environmental Impact, in the discussion of diesel sales. Tables
V—i and V—2 show the breakdown of new light—duty vehicle and truck
saLes by manufacturer for 1978. These two tables are combined in
Table V—3 to yield a breakdown of combined light—duty vehicLe and
light—duty truck sales by manufacturer. Two assumptions were made
to combine the two tables; first, the light—duty truck data in
Table V—2 includes the sale of trucks having a gross vehicle weight
(GVW) between 8,500 and 10,000 pounds which are actuaLLy heavy—duty
vehicles by EPA’s definition. These heavy—duty vehicles represent
about 57 of total sales up to 10,000 pounds GVW, but the 5% does
not necessarily hold for each manufacturer. For this analysis,
however, the 5% figure should be accurate enough, and the sales
shown in Table V—2 were multipLied by 0.95 before being added to
the sales in Table V—i. Second, a further breakdown of the “Other”
category in Table V—2 was not available. The assumption was made
that these sales would apportion themselves among the manufacturers
in Table V—i not represented in Table V—2.
The breakdown of Light—duty sales for 1978 shown in Table V—3
will be assumed to stay constant in the future. The total number
of vehicles sold will be assumed to increase 2% per year com-
pounded. Table [ —5 in Section I shows the fraction of light—duty
sales which are expected to be diesel. From this and the total
Light—duty sales for each year, the total sales of light—duty
diesels for 1984 and 1988 can be calculated. However, each manu-
facturer couLd design and produce its own trap oxidizers and have
its own production volume. If this was the case, then the produc-
tion of each manufacturer must be determined. To do this the data
in Table V—3 can be used but the diesel fraction of total sales
must be known for each manufacturer. Estimates of these fractions
can be found in Table 1—4 for 1985 and 1990. Using linear inter-
polation, these figures have been estimated and are shown in Table
V—4. The fractions for General Motors have been taken from Table
1—3. From all of the above information, the number of light—duty
diesels sold by each manufacturer between 1984 and 1988 can be
determined. These figures are shown in Table V—5. Now that the
necessary corporate production data are available, it will be
helpful to step aside for a moment and examine the theory of the
effect of production volume on the cost of production.
In manufacturing, it is a common occurrence that the cost of
production decreases with experience. This experience is usually
measured in terms of accumulated production. The relationship
between cost and accumulated production is called a learning
curve and is usually described by the logarithmic function:
69
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Table V—i
Breakdown of New Passenger Car Sales in the U.S.
by Manufacturer — 1978 1/
Percentage of
Manufacturer New Car Sales New Car Sales
General Motors 5,285,282 47.6%
Ford 2,582,702 22.8%
Chrysler 1,146,258 10.1%
ANC 170,739 1.5%
vw 2/ 239,306 2.1%
Mercedes—Benz 46,695 0.4%
Volvo 50,880 0.4%
Fiat 60,435 0.5%
BMW 31,457 0.3%
Audi 40,878 0.47.
Peugeot 9,061 0.1%
Other Imports 1,544,385 13.7%
TOTAL 11,308,078 100.0%
1/ Automotive News, 1979 Market Data Book Issue, April 25, 1979,
pp. 18 and 52.
2/ Domestic and imported.
70
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Table V—2
U.S. Sales of Light—Duty Trucks
by Manufacturer for 1978 1/
Number Percent of
of U.S. Light
Manufacturer LDT Sales Truck Market
Chevrolet 1,233,932 35
GMC 283,540 8
Ford 1,219,693 34
Chrysler 404,514 11
ANC/Jeep 163,548 5
IHC 3b,065 1
Other Manufacturers 2/ 210,041
TOTAL 3,551,333 1007.
Source: Automotive News, 1979 Market Data Book, p. 44
1/ LDT defined as 0—10,000 lbs. GVW.
2/ Includes imports.
71
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Table V—3
Breakdown of Combined Light—Duty Vehicle
and Light—Duty Truck Sales in U.S. in 1978 1/
Percentage of
Manufacturer New Car Sales New Car Sales
General Motors 6,826,880 46.5%
Ford 3,741,410 25.5%
Chrysler 1,530,546 10.4%
ANC 326,110 2.2%
262,716 1.8%
IHC 34,262 0.2%
Mercedes—Benz 51,154 0.4%
Volvo 55,339 0.4%
Fiat 66,009 0.4%
BMW 34,801 0.2%
Audi 45,337 0.3%
Peugeot 10,176 0.1%
Other Imports 1,697,105 11.6%
TOTAL 14,681,845 100.0%
1/ Light—duty trucks defined as 0—8500 pounds GVW.
72
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Table V-4
Projected Percentage of Diesel—Powered
Light—Duty Vehicles Sold by Manufacturer
Manufacturer 1984 1985 1986 1987 1988
General Motors 12% 13.8% 17.5% 22% 23%
Ford 8% 10% 11% 12% 13%
Chrysler 8% 10% 12% 14% 16%
ANC 8% 10% 12% 14% 16%
VW 1/ 42% 42% 46% 50% 55%
Mercedes—Benz 66% 70% 74% 78% 82%
Peugeot 66% 70% 74% 78% 82%
Volvo,Fiat, 8% 10% 12% 14% 16%
1/ Includes Audi.
73
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Table V—5
Light—Duty Diesel Sales by Manufacturer
(Excepting Rabbits) Between 1984 and 1988
in Thousands of Vehicles (Percents of Total)
Manufacturer 1984 1985 1986 1987 1988
General Motors 893 1082 1400 1795 1914
(60.1%) (58.7%) (62.1%) (69.6%) (65.2%)
Ford 326 430 483 537 593
(21.9%) (23.3%) (21.4%) (20.8%) (20.2%)
Chrysler 134 175 215 255 298
( 9.0%) ( 9.5%) ( 9.5%) ( 9.9%) (10.2%)
ANC 28 37 45 54 63
( 1.9%) ( 2.0%) ( 2.0%) ( 2.1%) ( 2.17.)
VW 1/ 36 38 43 47 53
— ( 2.4%) ( 2.1%) ( 1.9%) ( 1.8%) ( 1.8%)
Daimler—Benz 43 47 51 55 59
( 2.9%) ( 2.6%) ( 2.3%) ( 2.1%) C 2.0%)
Peugeot 10 12 13 14 15
( 0.7%) C 0.7%) ( 0.6%) C 0.5%) ( 0.5%)
Fiat 5 7 8 10 11
( 0.3%) C 0.4%) ( 0.4%) ( 0.4%) ( 0.4%)
BMW 3 3 4 5 6
( 0.27.) ( 0.2%) ( 0.2%) C 0.2%) ( 0.2%)
IHC 3 3 4 5 6
( 0.2%) ( 0.2%) ( 0.2%) ( 0.2%) ( 0.2%)
Volvo 5 7 8 10 11
( 0.3%) ( 0.4%) ( 0.4%) ( 0.4%) ( 0.4%)
TOTAL 486 1842 2274 2787 3029
(100%) (100%) (100%) (100%) (100%)
!/ Includes Audi, excludes Rabbits.
74
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, ln(l.O—z)
( 2 ‘ 1n2 ‘ (1)
Cl ‘P1’
where,
P 1 and P 2 = two different levels of accumulated production.
z = the fraction or percent that costs are reduced
each time the accumulated production is doubled.
C 1 and C 2 = costs of the item with total accumulated produc-
tion of P 1 and
For the purposes of this analysis, z will be assumed to be
0.12, or that the cost of a trap—oxidizer system will decrease 12%
each time the accumulated production is doubled (based on discus-
sions with experts in the emission control technology costing
field). Given the cost at a specified accumulated production, a
new cost at a different production can then be found using equation
(1).
A number of different costs of trap—oxidizers are important to
this analysis. First, the fleet—wide average cost for each of the
first five years of trap—oxidizer usage is important because it can
be coupled with vehicle production estimates to determine the
five—year aggregate cost of the 1984 standard. This aggregate cost
is an important indicator of the effect of a regulation on the
economy. Second, the system cost to small manufacatUrers is
important. If it is assumed that each manufacturer will produce
his own traps, then a small manufacturer will have a small produc-
tion volume, resulting in a higher cost. Third, it is similarly
important to determine the cost to a large manufacturer, as it
could be considerably lower than the cost to smaller manufacturers
if these small manufacturers do not purchase their systems from a
larger supplier. It is important to know this differential cost.
The fleetwide average cost of trap—oxidizer systems will be deter-
mined first, followed by the costs to both the smallest and the
largest manufacturers. These costs will be determined for each of
the first five years of trap—oxidizer production.
The fleetwide average cost of trap_oxidizers iS simply a
sales—weighted average of the costs to each manufacturer and is
described by the equation:
N
E C.. xP..
i=l 13 (2)
ave ,j N
E P..
13
1=1
75
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where,
Cve = Sales—weighted average cost in years.
C. = Cost of item to manufacturer i in year j.
= Production of manufacturer i in year j.
M = Number of manufacturers.
The cost of each component (or the system) to a manufacturer
(c 1 ) will depend on his total production, and the number of
different components (or systems) needed. For items such as traps,
throttle assemblies, exhaust pipes, etc., a different component
will be needed for each basic engine size (4—cylinder, 6—cylinder,
8—cylinder). For other items such as thermocouples and electronic
control units, one type can be used on all the manufacturers
models. In general, if it is assumed that a manufacturer will
produce equal amounts of each component (or system) type, then,
using equation (1), the average cost to each manufacturer (c ) is
as follows:
j ( ln(1.0 — Z) )
1n2
C.. C x k1 1k (3)
ref ( )
NxP
ref
where,
N = Number of types of each component.
ref Reference production volume.
Cref = Cost of component at a production volume of ref
If 0.12 is substituted for z, then equation (3) becomes:
.3
—0.1844
C.. C x k 1 ik (4)
ref ( )
NxP
ref
This relationship for C can now be substituted into equation (2)
which yields:
76
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J
z p
M
P.. x C x k = 1 —0.1844
ref ( )
C .. NxP
ave,j 1 ref
M
z p.
1=1 U
or
z p.,
= I , —0.1844
‘NxP (6)
C . C x Ll ref
ave,j ref ( M
i=1
Once the reference production ref is chosen and the Cref
determined, equation (6) will allow the average cost for all
manufacturers to be determined in any given year.
As will be seen below, there are a number of components in a
trap—oxidizer system and the cost of each has to be determined
separately. Rather than use equation (6) in its present state for
each of these components, an intermediate step can be made which
will reduce the total number of necessary calculations. Except for
Cref and N, the right—hand side of equation (6) is independent of
the component being examined. ref can be chosen to be the same
for all components. As explained above, there will only be two
sets of values for N; one set for those components which will need
to vary with engine size, and one set for those that will not.
Thus, the value for (Cave,j/Cref) can be calculated once for
each set of values for N. For components such as thermocouples and
electronic countrol units, only one type should be needed for a
manufacturer’s entire line, and N should be 1.0 for all manufac-
turers. For components which depend upon basic engine class, N
should be the number of basic engine classes a manufacturer will
produce. A basic engine class will be assumed to be characterized
by the number of cylinders in the engine. General Motors, Ford and
Chrysler will be assumed to build three basic engine classes. AMC,
VW and Daimler—Benz will be assumed to build two classes. Fiat,
Peugeot, BMW, International Harvester, and Volvo will be assumed to
build a single engine class.
The production data shown in Table V—5 can now be used direct-
ly to calculate (Cavei/Cref) for the years 1984—1988 (jl5). ref
will be assumed to 6 e 300,000 units. The results are shown in
Table V—6. As can be seen, the cost of components which vary with
basic engine class (N = 1,2, and 3) starts out 15% greater than the
77
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Table V-6
Values for the Ratio of the Actual Cost of a Component
to Its Cost at an Accumulated Production of 300,000 Units
1984 1985 1986 1987 1988
1 2 3 4 5
Fleetwide Average
N 1 0.955 0.823 0.742 0.683 0.648
N = 1, 2, & 3 1.15 0.993 0.896 0.825 0.783
Largest Manufacturer (GM)
N = 1 0.818 0.706 0.640 0.592 0.558
N 1, 2, & 3 1.001 0.865 0.784 0.724 0.684
Smallest Manufacturer (IHC)
N = 1 2.34 2.06 1.87 1.74 1.63
78
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basic engine class (N = 1,2, and 3) starts out 15% greater than the
cost at an accumulated production of 300,000 units (1984) and four
years later is 22% less than the cost at 300,000 units. A similar
result occurs for those uniform components (N = 1). In 1984, the
cost is 4.5% less than the cost at the reference production and by
1988 the cost is 35% Less than Cref.
Equation (6) can also be used to calculate similar values for
just the largest manufacturer and just the smallest manufacturer.
This will be useful in determining the range of costs that will
occur between manufacturers, which has already been mentioned as an
important piece of information for subsequent analyses. These
results are also shown in Table V—6. As can be seen, the costs for
General Motors could be about 13% less than the fleet average,
based on differences in production volumes, while the costs for
International Harvester could be slightly over twice the fleet
average. The results for International Harvester (IHC) are conser-
vative since it was assumed that IHC would produce its own trap—
oxidizer system at very low production volumes. This may not be
the case as IHC may choose to purchase these systems from a sup-
plier and take advantage of higher production volumes. This
statement is true for all of the smaller manufacturers shown in
Table V—5. If a number of these smaller manufacturers were able to
purchase trap—oxidizer systems from a large supplier, the fleetwide
average cost would be lower than that indicated in Table V—6.
EPA’s original cost estimates of the individual components of
a trap—oxidizer system were taken from a study of the costs of
emission control systems.1/ The formula used to determine the
retail price equivalent of each item is shown below.
Retail . . Fixed
Direct Direct
Price = 1k . ) + ( ) + (Variable)]
iyiaterial Labor
Equivalent Overhead
[ 1 + (0.2 Corporate ) + (0.2 Supplier)] + (Tooling)
Allocation Profit Expense
Land & Dealer
+ (Building)] x 11 + (0.2 Corporate ) + (0.2 Corporate) + (0.4 Overhead)]
Allocation Profit
Expense & Profit
+ (Research & + (Tooling) (7)
Development Expense
or, in abbreviated form:
1/ Lindgren, Leroy H., “Cost Estimations for Emission Control
Related Components/ Systems and Cost Methodology Description,” Rath
and Strong for EPA, March 1978, EPA—460/3780O 2 .
79
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RPE = [ (DM + DL + OH)(l.4) + TE + LBE](1.8) + RD .+ TE (8)
Direct materials entail those materials of which a given component
is comprised. Direct labor includes the cost of laborers directly
involved in the fabrication of a given component. Overhead in-
cludes both the fixed and variable components of overhead. The
fixed portion includes supervisory salaries, building maintenance,
heat, power, lighting, and other costs which are substantially
unaffected by production volume while the variable portion includes
small expendable tools, devices, and materials used in production,
repairs and maintenance made to machines directly involved, and
other overhead costs which tend to vary with production volume. A
straight 407. of the direct labor amount was used to determine all
overhead costs.
A figure of 207. applied to the sum of material, labor, and
overhead costs was used to determine corporate allocation. In
other words, this is the amount needed to cover the supplier’s
support from its front office. Also, to the sum of material,
labor, and overhead costs, a figure of 207. was applied to determine
the supplier’s profit. Approximately half of this 207. is used to
pay corporate taxes with the remaining portion being divided
between dividend disbursements to stockholders and retained earn-
ings, which are used to finance working capital requirements
(increases in current assets and/or decreases in current liabili-
ties) and/or new capital expenditures (long—term assets).
Tooling expense consists of four components: one year re-
curring tooling expenses (tool bits, disposable jigs and fixtures,
etc.); three year non—recurring tooling expenses (dies, etc.);
twelve year machinery and equipment expenses; and twelve year
launching costs (machinery foundations and other incidental set—up
costs) which was assumed to be 10% of the cost of machinery and
equipment.
The sum of the above costs, material, labor, plant overhead,
tooling expense, corporate allocation, and profit, makes up the
price (or, in the case to a division, transfer price) which the
supplier charges the vehicle manufacturer for a given component.
At the vehicle assembly level, 207. of this price is charged or
allocated for the vehicle manufacturer’s corporate level support
and 20% for corporate profit. Also, a figure of 40% is applied to
the supplier price to account for the dealer’s margin which in-
cludes sales commissions, overhead, and profit.
Because of the need, in many instances, to make modifications
to the engine or body to incorporate a component and to assemble it
into a vehicle, these have also been accounted for at the division
level and transferred to the corporate level at vehicle assembly.
Lindgren’s study primarily focused on determining the manu—
80
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facturing costs of emission control equipment. Much effort was
expended to accurately determine the cost of materials, Labor,
tooling, etc. EPA has available a number of confidential cost
estimates from emission—control equipment suppliers and these costs
confirm Lindgren’s estimates at the vendor level.
Less resources were available to Lindgren to determine over-
head costs and profit margins and, in general, rules of thumb were
used in equation (8). These estimates of overhead costs and profit
margins at the corporate and dealer levels could be improved with a
more detailed analysis. Overhead and profit at the vendor level
will not be reexamined because the independent vendor estimates
mentioned above confirmed Lindgren’s estimates at that level.
The first two factors to be examined are those indicating the
corporate overhead and corporate profit. Typical levels of over-
head and profit can be obtained from Moody’s Industrial Manual.2/
An examination of the financial data of the three largest American
manufacturers reveals some interesting facts. Corporate overhead
as a percentage of cost of saLes (in Lindgren’s terminology, vendor
cost plus research and development and tooling expenses) is ap-
proximately the same for the three manufacturers and very close to
10% for 1976—1978. This overall factor is reasonable to use for
allocating overhead to emission control devices since these devices
are an integral part of the vehicle and not an optional accessory.
The net income before taxes as a percentage of cost of sales
differs considerably between the three manufacturers. Between 1976
and 1978, General Motors’ profit in these terms was the highest
(14%) and Chrysler’s the lowest (1.1%). Ic does not seem appro-
priate to include the Chrysler profit in any calculation of in-
dustry profit because it does not reflect the necessary long—term
profit margin of a healthy corporation. It seems most.appropriate
to simply use the profit level of General Motors as the appropriate
level as it is the industry leader. Even if Ford and Chrysler
are not attaining the profit level of General Motors, that is their
goal and it does signify the profit level of a healthy corpora-
tion. Thus, 10% will be used to allocate corporate overhead and
14% for corporate profit.
The last factors to be determined are the levels of dealer
overhead and profit. An important tenet to keep in mind here is
that we are searching for the incremental cost at the dealer level
of adding emission control devices. It may not be appropriate to
allocate overhead to these devices at the average rate because the
presence of these devices may not affect the cost of overhead. On
the other hand, profits should increase because the presence of the
emission control devices will raise the cost of the vehicle to the
dealer, increasing his capital investment.
2/ Moody’s Industrial Manual , 1979, Vol. 1, A—I.
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The net profit on sales after taxes of the average motor
vehicle dealer in 1977 was 1.46%.3/ The average profit on sales
before taxes would then be about 3%. As emission controls are an
integral part of the vehicle, the average profit on the entire
vehicle would seem appropriate for emission control devices.
The area of dealer overhead, however, may be one cost which
should not be allocated at the existing rate (i.e., some percentage
of sales). As mentioned before, it is not the average cost that is
being examined, but the incremental cost, the marginal cost. Is
the addition of a pollution control device really going to increase
the overhead? The costs of land and buildings should not in-
crease. It doesn’t take any more space to store a car with p 01—
lution controls than one without the controls. At most, some
additional space may be needed to store extra parts, but even this
should rightly be charged as overhead for maintenance costs, and
should be charged to persons paying for the maintenance or buying
the part. Few would argue that the cost of replacement parts does
not include the cost of storage.
The number of secretaries or salesmen should not be affected
either. No extra paperwork is involved on the dealer level because
of emission controls. If the cost of the device is small enough,
sales should not be impacted significantly, particularly since
competitors will have to increase their prices by approximately the
same amount.
Lastly, it could be said that mechanics will have to be
retrained to be able to maintain the new devices. However, this
cost, like the space needed for parts storage, should be placed on
the maintainance fee, probably as the cost of labor. Thus, it too
should not be added to the initial price of the vehicle.
Now that revised estimates of corporate and dealer overhead
and profit have been developed, these revised estimates can be
substituted into equation (7) to form a new costing equation. The
new factors for corporate overhead and corporate profit and 0.10
and 0.14, respectively. However, since research and development
costs and tooling expense were included in the cost of sales upon
which these factors were based, these two costs (RD and TE) should
also be increased by the overhead and profit factors in the new
costing equation. The new factor for dealer overhead and profit is
0.03. However, this factor was based on the cost to the dealer,
which includes corporate overhead and profit. Thus, the entire
cost up to the dealer level should be increased by 3%. The re-
sulting equation is shown below:
RPE (((DM + DL + OH)(1.4) + TE + LBE)
+ RD + TEI(1.24)(1.O 3 ) (9)
3/ Dun’s Review , September 1978, Vol. 112, No. 3, pp. 124, 125.
82
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Now that the revised retail cost methodology is available, the
next step will be to calculate the cost of the various components
which together form a trap—oxidizer system. A standard production
volume of 300,000 units will be used for the time being. After the
Cost of all the components has been determined, the ratios shown in
Table V—6 will be used to calculate the fleerwide average costs and
the cost to both the smallest and largest manufacturer.
The major portion of the cost of a trap oxidizer is the trap
itself. In the Draft Regulatory Analysis, this was approximated by
the cost of a pelleted oxidation catalyst. Though no comment was
directly received concerning this approximation, the most promising
trap designs fall closer to a monolithic catalyst than a pelleted
catalyst. In some cases, actual monolithic substrates are being
used with and without washcoat and noble metals for prototype trap
testing.4/ In other cases, the trapping material is alumina—coated
steel wool or saffil fiber.5J The manufacturing of a trap out of
these materials should follow more closely to that of a monolithic
catalyst than to a pelLeted catalyst. Rather than continue using a
pelleted catalyst to approximate trap Costs, then, the cost of a
monolithic catalyst will be used instead.
The costs for three trap volumes wiLl be calculated, account-
ing for the different sizes which will be required by different
engine sizes. The basis for the sizes is the successful testing of
a 5.3—liter trap fitted to an Opel 2100D.3/ Extrapolations of
trap size were made to larger and smaller engines using the ratios
of the fuel consumptions over the FTP of the various engines
(vehicles). Fuel consumption is a good, available indicator of
volumetric flow through the trap, which should be one of the main
considerations in sizing the trap. Assuming that typical fuel
economies of 4—, 6—, and 8—cylinder engines were 35, 28, and 21
miles per gallon, respectively, the trap volumes were calculated to
be 4.6 (281), 5.8 (354), and 7.3 (445), liters (cubic inches),
respectively.
Lindgren (p. 145) has determined the cost of a monolithic
catalyst as a function of volume and noble metal content and put it
in a formula equivalent to equation (8):
RPE (Trap) (NN + $2.52 + 0.1013 x V) x 2.52 + $5.995 (10)
Where:
4/ Perininga, Thomas, TAEB, EPA, “Diesel Particulate Trap Study:
Interim Report on Status of Study and Effects of Throttling,”
Memorandum to Ralph C. Stahman, Chief, TAEB, EPA, May 18, 1979.
5/ Rykowski, Richard A., SDSB, “Size Considerations Concerning
the Use of Trap—Oxidizers in Light—Duty Diesels,” Memorandum to
Robert E. Maxwell, Chief, SDSB, EPA 1 October 15, 1979.
83
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RPE (Trap) = Retail price equivalent of a trap (monolithic
catalyst).
NM = Cost of noble metals at manufacturing level.
V Volume of trap in cubic inches.
The multiplicative factor of 2.52 in equation (10) is the
product of the factors for vendor overhead and profit (1.4) and
corporate and dealer overhead and profit (1.8). In the revised
methodology of equation (9), the first factor remains the same, but
the second factor becomes 1.277 (1.24 x 1.03). Also, the factor of
1.277 is applied to the $5.995 cost of research and development and
tooling. Thus, in terms of the revised methodology of equation
(9), equation (10) becomes:
RPE(Trap) = ((NM + $2.52 + 0.1013 x V) x 1.4 + $5.995) x 1.277 (11)
The trap volumes needed for equation (11) are already avail-
able, but the noble metal loadings are not. At this point in time,
it is not known whether or not diesel particulate traps require
noble metals. The purpose of the noble metals, if present, would
be to lower the temperature necessary to ignite the trapped par-
ticulate and possibly to aid the oxidation process to reach carbon
dioxide and water. To cover the range of possibilities, two
loadings will be assumed, one with no noble metals and one with
oxidation—promoting metals (Pt and Pd) at a level found in current
oxidation catalysts for gasoline engines, which is around 0.012
gram per cubic inch with a 2:1 ratio of Pt to Pd. Noble metal
costs are currently around $8.67 per gram for Pt and $2.72 per
gram for Pd.6/ However, since the Lindgren Costs represent 1977
prices and a general inflation rate of 8 percent per year will be
used to adjust the total costs, these current (1979) noble metal
costs will be divided by 1.1664 so that when they are adjusted for
inflation later, they will represent 1979 prices. Using Lindgren’s
formula for the cost of the noble metals (p. 134):
NM $7.43 x 0.008 V + $2.33 x 0.004 V ÷ $0.14 x 0.0012 V
or
NM = $0.0690 V (12)
The last term accounts for manufacturing costs.
Equation (11) includes the cost of a washcoat. However, if no
6/ American Metal.s Market , June, 1979, reduced by 23 percent to
reflect prices available to large—volume buyers (auto manufac-
turers).
84
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noble metals are to be present, the washcoat should not be neces-
sary and its cost should be deleted. From a breakdown of catalyst
costs at various volumes (Lindgrert p. 360), it is found that the
cost of the washcoat is proportional to the volume of the catalyst
and represents 10.3 percent of the 0.1013 term in equation (11), or
0.0104 V. Subtracting this and the noble metaL cost from equation
(11) yieLds the cost for a trap without washcoat or noble metals:
RPE (Trap) = ((S2.52 + 0.0909V) x 1.4 + 5.995) x 1.277 (ha)
Two final adjustments are needed before calculating the costs
of the traps. One, inflation needs to be considered. The costs
that Lindgren quotes are from 1977. An 8 percent per annum
infLation rate will be used to convert these costs to 1979 costs,
or a factor of 1.1664. Two, production volume needs to be taken
into account. Lindgren assumed a production volume of 2,000,000
catalysts (p. 115). The production volume of interest here is
300,000 units. Using equation (1) with Z = 0.12, it is found that
the cost should be a factor of 1.364 higher at the Lower production
volume. Combining the infLation and production factors, the costs
determined by equations (11) and (ha), should be increased by a
factor of 1.591.
The necessary equations ((11), (ha), and (12)) are now avaiL-
able with which the cost of the trap can be determined. Substi-
tuting equation (12) into equation (11) and multiplying equations
(11) and (ha) by 1.591:
Trap cost — No noble metals
RPE (Trap) (($2.5.2 + 0.0909 V) x 1.4 + 5.995) x 1.277 x 1.591
or
RPE (Trap) $19.35 + 0.2586 V (13)
Trap cost — With noble metals
RPE (Trap) (( 2.52 + (0.1013 + 0.0690)V) x 1.4 + 5.995) x
1.277 x 1.591
or
RPE (Trap) $19.35 + 0.4844V (13a)
Using equations (13) and (13a) the costs of the traps at
various volumes can now be calculated. These are shown in Table
V—7.
Port liners, insulated exhaust manifolds and an insulated
85
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exhaust pipe may also be necessary to ensure that the exhaust gas
temperature remains high enough to permit oxidation in the trap.
From Lindgren (p. 195), the manufacturer’s cost (vendor cost plus
research and development and tooling) of port liners for a 4—cyl-
inder engine is $5.40. Taking inflation (16.64 percent) and
corporate and dealer overhead (27.7 percent) would increase this to
$8.04. The production volume assumed was 400,000 engines. Using
equation (1), with z 0.12, to convert to 300,000 units results in
a cost increase of 4.8 percent to $8.43, or $8. It will be assumed
that port liners will cost 50 percent more for a 6—cylinder engine
($13) and 100 percent more for an 8—cyLinder engine ($17).
These costs are shown in Table V—7.
The cost of an insulated exhaust manifold has also been
indirectly determined by Lindgren (pp. 171—90). From Lindgren ’s
treatment of a thermal reactor, the cost of simply insulating the
manifold can be determined. For a 4—cylinder engine, the manu-
facturer’s cost of ceramic liners and insulation is $6.55 (p. 179).
Research and development cost of $1.00 per manifold (p. 180) will
be taken to be entirely due to the thermal reactor function and
will be taken to be zero for simply insulating a manifold. Vehicle
assembly and engine modifications amount to $0.69 for the entire
thermal reactor (p. 180). Subtracting from this the cost of
assembling a standard manifold ($0.56 for a 6—cylinder engine, p.
188) results in a negligible net cost and will not be considered.
it will be assumed that the cost of the manifold itself will not
change. This should be multiplied by 1.277 (see equation (9)) to
obtain the retail price equivalent, which is $8.36. The production
volume assumed was the same as in the case of port Liners above,
400,000 units. Thus, the conversion factor for inflation and
production volume is the same as above, 1.222 (1.1664 x 1.0489).
Taking this factor into account, the cost of insulating a 4—
cylinder manifold in 1979 is then $10.22 or $10. The cost of
insulating a manifold for a 6—cylinder engine will be assumed to be
50 percent more ($15) and 100 percent more for an 8—cylinder engine
($20). These costs are shown in Table V—7.
Looking next at the exhaust pipe, there are two levels at
which it can be improved. One, the standard steel material must be
converted to stainless steel if the system will, be expected to last
100,000 miles. There is no guarantee that people would replace a
rusted—out exhaust pipe before it developed holes, which would
aLlow exhaust to bypass the trap and also cool the exhaust, pos-
sibly to the point of preventing any oxidation from ocurring. Two,
the exhaust pipe may have to be insulated to keep the exhaust
temperature high enough for oxidation to occur.
The cost of changing the exhaust pipe Co stainless steel can
be taken from Lindgren. The manufacturing cost (DM + DL + OH
in equation (8)) of a standard steel exhaust pipe is $2.66 (6—
cylinder engine) and $4.60 (8—cylinder engine) (p. 254 and 258).
86
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Table V—7
Estimated Cost of a Trap—Oxidizer System !/
Number of Cylinders in Engine
Four Six Eight
Original Revised Original Revised Original. Revised
Trap 2/
Without catalyst $70 92 75 111 134
With catalyst 155 191 235
Port Liners 10 8 16 13 18 17
Stainless Steel 0 13 0 13 0 22
Exhaust Pipe 3/
Insulate Exhaust 14 34 23 34 33 53
Pipe
Insulate Exhaust 0 10 0 15 0 20
Manifold
Electronic Control 22 34 22 34 22 34
Unit
Sensors 5 8 5 8 5 8
Throttle Body 8 15 8 15 8 15
Ac t u a to r
Electro—Mechanical 5 5 5
Control
Muffler (Credit) —15 —9 —15 —11 —15 —13
!/ “Cost Estimations for Emission Control Related Components!
Systems and Cost Methodology Descriptions,” Rath and Strong for
EPA, March 1978, EPA—460/3—78—002. Assumed production volume of
300,000 units.
2/ Costs shown are for an oxidation catalyst, 8 liters for
an 8—cylinder engine, 6 liters for a 6—cylinder engine, and 4.9
liters for a 4—cylinder engine.
3/ Includes credit for steel exhaust pipe which it replaces; $710
for 4— and 6—cylinder and $12—17 for 8—cylinder engines.
87
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Tooling costs are only $0.10 per pipe. Using equation (9), the
retail price equivalents of these two pipes are $4.88 and $8.44,
respectively. The retail price equivalents of stainless steel
exhaust pipes are $13.89 and $24.24 respectively (p. 251 and
equation (9)). The cost of converting to stainless steel is then
$9.01 for a 6—cylinder engine and $15.80 for a 8—cylinder engine.
The assumed production in both cases was 1)000,000. Using equation
(1), these costs need to be increased by 21.8 percent to convert to
a production of 300,000 units. They also need to be increased by
16.64 percent because of inflation. tn total, then, the cost of
converting the exhaust pipe to stainless steel is $13 for a 6—
cylinder engine and $22 for an 8—cylinder engine. It will be
assumed that the cost for a 4—cylinder engine will be the same as
that for a 6—cylinder engine. These costs are also shown in Table
V—7.
The cost of adding a double wall to the exhaust pipe with
insulation in between is next to be determined. Again from Lind—
gren (p. 272 and equation (9)), the retail price equivalent of a
double—walled, stainless steel, insulated pipe is $37.98 for
a 6—cylinder engine and $61.33 for an 8—cylinder engine. Sub-
tracting the costs of the stainless steel pipe calculated above
leaves $24.09 (6—cylinder) and $37.09 (8—cylinder). Using the same
adjustments for production volume and inflation, and the same
assumption concerning the 4—cylinder engine, the cost of converting
a stainless steel exhaust pipe to a double—walled, insulated,
stainless steel pipe is $34 for a 4— or 6—cylinder engine and
$53 for a 8—cylinder engine (Table V—7).
If the exhaust pipe is to be made out of stainless steel,
whether single or double—walled, it should last the entire life of
the vehicle. This means that replacements which would have normal-
ly occurred with steel pipes will no longer occur with stainless
steel pipes. This will result in a reduction in vehicle operating
costs. It will be assumed that exhaust pipes normally need to be
replaced once during a vehicle’s life. For convenience, this will
be taken to occur halfway through the vehicle’s life, after five
years. At this point, the consumer does not save only the retail
price equivalent, but the aftermarket Cost and labor costs.
Lindgren estimates aftermarket costs (material) to be four times
the vendor cost. Previously, the retail price equivalents for
steel exhaust pipes were found to be $4.88 (4— and 6—cylinder) and
$8.44 (8—cylinder). These costs had not been adjusted for pro-
duction (they represent a production volume of one million units)
or inflation (they are 1977 costs). Using equation (1) and multi-
plying by 1.1664 for inflation, the proper 1979 retail price
equivalents are $6.93 (4— and 6—cylinder) and $11.99 (8—cylinder).
The 1979 vendor costs (using equation (9)) are $5.43 (4— and
6—cylinder) and $9.39 (8—cylinder). Using Lindgren’s factor of
four, the aftermarket prices would be $22 (4— and 6—cylinder) and
$38 (8—cylinder). A survey of muffler shop prices confirmed these
88
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figures and also revealed that the cost of clamps and brackets
amounted to about 5 percent of the cost of the exhaust pipe and
labor costs were about 25 percent of the total material cost.
Thus, the complete cost (in this case savings) of replacing an
exhaust pipe would be $29 (4— and 6—cylinder) and $50 (8—cylinder).
To be comparable to the initial price increases discussed in this
section, these savings need to be discounted back five years since
the savings will not occur until then. Using a 10 percent discount
rate, the savings (in the year the car was bought) would be $18 (4—
and 6—cylinder) and $31 (8—cylinder).
The oxidation control unit was originally estimated to cost
$35. Included in this figure were $22 for half of an electronic
control unit and $13 for sensors, thermocouples and a throttle for
raising the temperature of the exhaust. The revised estimates are
shown in Table V—7 and are based on the following. In his study,
Lindgren solicited estimates of the cost of an electronic control
unit (ECU) which monitored and controlled a large number of sensors
and controllers (p. 320). This type of ECU should be of the same
capacity as that needed to control the oxidation process of a
trap—oxidizer system. The industry estimate was $45. Taking this
to be a vendor level cost, the retail price equivalent would be
$57. Inflating this to 1979 prices, the cost increases to $67.
However, half of this cost will be alotted to particulate control
and half to NOx control. The presence of the electronic control
unit wilL allow the use of programmed exhaust gas recirculation
systems, which should provide reductions in NOx emissions from
light—duty diesels. These reductions are definitely needed as
evidenced by the recent need to waive the 1.0 g/mi (0.62 glkrn) NOx
standard to 1.5 g/mi (0.93 g/km) NOx for many diesel—powered
light—duty vehicles. Thus, the cost of the unit due to diesel
particulate regulations is $34, which is shown in Table V—7.
The costs of the sensors, throttle body and actuator can also
be taken from the same Lindgren table (p. 320). Allowing for two
thermocouples near the trap, an engine speed sensor, and a rack
position sensor, the vendor cost at a production volume of 300,000
is approximately $5. With two year’s inflation, this cost would
increase to around $6. If equation (9) is used to calculate the
retail price equivalent, the cost becomes $S. The throttle
switch and body should cost about $10 at the vendor level (p. 320)
at a production volume of 300,000 units. With inflation and
conversion to retail price equialents, the cost should be $15.
Both costs are shown in Table V-7.
It may also be possible that a much simpler control device
would suffice in the situation. If alL that was needed was a
periodic boost in exhaust temperature during some general engine
condition, then a controller on the order of an automatic choke or
an odometer—controlled maintenance light (e.g., EGR light) should
be satisfactory. For example, if the throttle actuator was keyed
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to the odometer and rack position, it could operate periodically,
for set period of time at a certain rack position. This type of
control system would only require two or three sensors and mechan-
ical or electrical connections to the throttle actuator. From
sensor costs shown by Liridgren (p. 320)and equation (9), this
system should only cost about $5. This option has been included
among the components shown in Table V—7.
It is very likely that addition of a trap to the exhaust would
allow either the muffler or resonator to be deleted. This would
result in a savings to the consumer, not only initially, but every
time the standard steel exhaust system would need replacement.
From Lindgren (p. 264) and equation (9), the retail price equiva-
lent of a muffler is $6.95 (6—cylinder) and $8.36 (8—cylinder) at a
production volume of 2,000,000. Using equation (1) to adjust to a
production volume of 300,000 units, the costs would be $9.47 and
$11.40, respectively. Finally, two year’s inflation would increase
these costs to $11.05 (6—cylinder) and $13.30 (8—cylinder).
Extrapolating linearly to a 4—cylinder engine results in a cost of
$8.80. These are shown in Table V—7.
The additional savings accrued during the life of the vehicle
come from not needing to replace the muffler (or resonator) when it
otherwise would have needed to be replaced. In this situation, the
prices being paid are not retail price equivalents, but afterinarket
prices and labor costs. Due to the large number of firms in the
aftermarket muffler business, it will be assumed that this market
is fairly competitive and that excess profits are not obtained.
The cost paid by the purchaser, then, is the actual cost to the
economy, excepting taxes which will be included for simplicity.
From Lindgren (p. 265), the aftertuarket material costs are
about four times the vendor level cost. The reasons for this
would be smaller volume purchases, storage, and transporation
costs. This relationship has been confirmed above in the case of
exhaust pipes. Using equation (9) to adjust the retail price
equivalents of Table V—7, the vendor level costs turn out to
be $6.90 (4—cylinder) $8.65 (6—cyLinder) and $10.41 (8—cylinder).
If aftermarkee prices are four times vendor—level costs, then the
aftermarket prices would be $28 (4—cylinder), $35 (6—cylinder), and
$42 (8—cylinder).
While it may seem that mufflers need replacement more often,
it appears that on the average, mufflers are replaced once every
five years.7/ There are, of course, regional and model—to—model
variations below and above this average. Given that light—duty
7/ “Car Maintenance in the U.S.A.,” Motor and Equipment Manufac-
turers Association, Vo].unte 1, 1977.
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vehicles have an average life of ten years, the savings from not
having to replace the muffler would only occur once, after five
years. The savings would include the cost of material, determined
above, and the cost of labor. A survey of local muffler shops
shows that typical labor costs are about 25 percent of material
costs, as evidenced above in the case of exhaust pipes. Given
this, the savings would be $35 (4—cylinder), $44 (6—cylinder) and
$52 (8—cylinder). Of course, to compare these values with the
initial vheicle price increases, they would have to be discounted
at 10 percent over five years, or by 38 percent. With discounting,
the savings would be $22 (4—cylinder), $27 (6—cylinder), and $32
(8—cylinder).
General Motors made some comments concerning the cost of the
last few components described. One, they stated that the elec-
tronic controL unit would cost twice as much as EPA’s original
estimate. General Motors stated that their cost estimates did not
include any profit, so their comment should be compared to the $34
cost in Table V—7. This revised cost ($34) is already 55 percent
higher than EPA’s original estimate ($22). The revised estimate of
$34 is based on industry estimates elicited by Rath and Strong. As
General Motors did not support their statement nor give any reason
why the Rath and Strong estimate should not be used, the revised
estimate of $34 should not be changed again. Two, General Motors
claimed that EPA did not account for the cost of thermocouples,
sensor and a throttle. Actually, $13 was allowed in the original
estimate, though it was not mentioned explicitly but implicitly
included in the cost of “electronic oxidation control.” As General
Motors did not present their own estimate and explanation of the
costs of these items, the revised estimates shown in Table V—7
should be used. The cost for the sensors includes the cost of two
thermocouples, an engine speed sensor and a rack position sensor.
General Motors also states that the muffler would still be
required after addition of the trap—oxidizer. The original deci-
sion that the muffler (or resonator) could be replaced was based on
discussions with General Motors themselves where they spoke of
replacing the muffler or resonator with the trap—oxidizer during
their tests. More recently, testing of traps by Texaco and EPA
have confirmed that these traps are effective silencers.8/,9/
Thus, it appears Likely that one of the two standard silencers can
be eliminated, and the other can be optimized to reduce what excess
noise is left. The credits for the original equipment muffler
shown in Table V—7 should be taken in subsequent system cost
8/ Penninga, T., TAEB, EPA, “Second Interim Report on Status of
Particulate Trap Study,’ t Memorandum to R. Stahman, Chief, TAEB,
EPA, August 28, 1979.
9/ Alson, Jeffrey, SDSB, EPA, “Meeting Between Texaco and EPA to
Discuss Particulate Trap Work,” Memorandum to the Record, October 15,
1979.
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calculations, as well as the operating cost credit resulting from
not having to replace the muffler.
Now that the cost of all the components has been determined,
the decision needs to be made concerning which of these components
will be needed on any given vehicle. As this is inherently a
projection, there will be a number of component combinations which
may be able to reduce particulate emissions to 0.2 g/mi (0.12
g/km), but it is also possible that they may not. There will also
be variations between models and manufacturers, as is usually the
case with a system as complex as a trap—oxidizer.
Four basic combinations appear to have varying degrees of
probability in being able to trap and oxidize diesel particulate
safely and efficiently. These are shown in Table V—8. At this
time, it does not appear likely that a simple trap will be able to
perform adequately by itself. Some additional features will be
necessary to ensure that the particulate will be oxidized effec-
tively and safely. Systems 1, I I, and III all include one or two
such features. System I includes a trap plus exhaust insulating
features to help retain exhaust temperature to promote oxidation.
It also includes a throttle to raise exhaust temperature controlled
by an electro—mechanical system. This control system would be
envisioned to be much simpler than that of a three—way catalyst or
electronic fuel. injection. The control system would be more on the
order of an automatic choke or an odometer—controlled maintenance
Light (e.g., EGR). The insulation of the exhaust pipe has been
omitted primarily because of its cost, which is $34—53. Road tests
on a Mercedes—Benz 300D have shown that the temperature drop
between the exhaust manifold and the trap inlet is only 15_200 C
with an uninsulated exhaust pipe.l0/ It would seem that this small
decrease in temperature can be made up elsewhere more economically;
using, for example, a throttle. Actually, the omission of an
insulated exhaust pipe was one of the prime reasons for including
a throttle in this system.
System II consists of a trap, a throttle and simple control
system, but instead of insulating features uses a coating of
noble metals to promote oxidation. System III consists of a trap,
a throttle and a sophisticated control system, but uses no insul-
ating techniques or catalytic materials.
Any one or all three of these systems may be able to trap and
oxidize diesel particulate successfully. However, there is some
chance that more will be needed, which leads to System IV. System
IV combines the oxidation—promoting features of Systems I and III,
10/ Springer, Karl J., “Investigation of Diesel—Powered Vehicle
Emissions: VIII. Removal of Exhaust Particulate from Mercedes
300D Diesel Car,” June 1977, EPA 460/3—77- O07, p. 34.
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Table V—8
Components Included in
Potential Trap—Oxidizer Systems
System System System System
I II I t t _________
Trap Trap Trap Trap
(no noble metals) (w/noble metals) (no noble metals) (no noble metals)
Stainless Steel Stainless Steel Stainless Steel Stainless Steel
Exhaust Pipe Exhaust Pipe Exhaust Pipe Exhaust Pipe
Port Liners Throttle Body Electronic Port Liners
and Switch Control Unit
Insulated Exhaust Mechanical Sensors Insulated Manifold
Manifold Control Exhaust
Throttle Body Throttle Body Sensors
and Switch and Switch
Mechanical Electronic
Control Control Unit
Throttle Body
and Switch
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consisting of a trap, throttle, port liners, insulated exhaust
manifold and sophisticated control. This system should be suf-
ficient in any case, and represents an upper bound of necessary
technology.
The costs of the four systems are shown in Table V—9. System
I is the least expensive, which is to be expected. However, System
II, which could be considered less likely to be viable than System
IV, is more expensive than System IV. This is primarily due to
three assumptions used to estimate the amount of catalytic material
on the trap. One, it was assumed that Pt and Pd would be the
catalysts used. Two, it was assumed that the catalyst Loading
would be that found on current oxidation catalysts, around 0.012
gram per cubic inch. Three, it was assumed that this loading would
be needed throughout the whole trap. It is possible that expensive
catalysts such as Pt and Pd may be avoided and more inexpensive
catalysts, such as silver nitrate, may prove sufficient. It is
also possible that the loading could be decreased or that the
catalyst would only be needed near the inlet to begin the oxidation
process, which would proceed thereafter thermally. Any of these
changes would lower the costs of System II and could make it
competitive with Systems I and III.
It is not possible to place any probability on the possibility
of any of these systems being used. It is quite possible that
System I will be used on some models, particularly those which may
be relatively close to the 1984 standard without a trap—oxidizer.
It is also possible that some models will need System IV. Rather
than give the systems a probability weighting which would have
little basis, the entire range of costs between Systems I and LV
will be used hereafter, as it does indicate the range of costs
which could occur. The cost of System IV will be taken to be the
maximum cost. It will, be assumed that System II will be used only
if the catalytic material or its loading can be changed to make it
competitive with Systems I and III.
The range of system costs (i ’Iv) of Table V—9 can now be
combined with the actual cost to reference cost ratios of Table V—6
to yield the actual cost of trap—oxidizer systems at the production
volumes expected. The costs for the trap, port liners, insulated
exhaust pipes, and exhaust manifolds, and the throttle body and
actuator should be multiplied by the ratios for N equal to 1, 2,
and 3 (except for the case of the smallest manufacturer where N is
always equal to 1). The costs for the control units and sensors
should be multiplied by the ratios for N equal to 1. The results
are shown in Table V—lO.
During the period between 1984 and 1988, the number of 8—
cylinder engines can be expected to decrease due to the need for
greater fuel economy. Thus, it should be reasonable to roughly
predict that an equal number of each engine size will be produced.
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Table V—9
Costs of Four Potential
Trap—Oxidizer Systems 1 /
Engine Size
Four— Six— Eight—
System Cylinder Cylinder Cylinder
I $134 $161 $200
II 179 213 264
III 153 170 200
IV 171 198 237
1/ Assumed production volume of 300,000 units, 1979 prices,
includes credit for replacement of muffler by trap.
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Table V—10
Estimated Costs of Trap—Oxidizer Systems
at Predicted Production Volumes
Largest Smallest
# of Engine Fleetwide Manufacturer Manufacturer
Cylinders Average ( GM) ( IHC )
1984 4 153—190 133—165
6 184—220 160—191
8 229—263 199—228 469—556
Ave. 189—224 164—195
1985 4 132—164 115—142
6 159—189 139—165
8 197—227 171—197 413—490
Ave. 163—193 142—168
1986 4 119—147 104—129
6 144—170 125—149
8 178—204 156—179 375—444
Ave. 147—174 128—152
1987 4 110—136 96—118
6 131—157 115—138
8 164—188 144—165 348—413 .
Ave. 135—160 118—140 ——
1988 4 104—129 91—1 12
6 125—149 109—130
8 155—179 136—155 326—387
Ave. 128—152 112—132
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The average cost for each year is then an ar Lhmetic average of the
costs for the three engine sizes. These are also shown in Table
V—S. For the smallest manufacturer, LHC, it was assumed that only
8—cylinder engines would be produced. The fleetwide average cost
in 1984 would be $189—224 per vehicle, and this should decrease to
$128—152 per vehicle in 1988. The costs for General Motors’
vehicles should be somewhat less, $164 195 per vehicle in 1984 and
$112—132 per vehicle in 1988. The costs for IUC would be much
greater, $469—556 per vehicle in 1984 and $326—387 per vehicle in
1988, if they produced their own trap—oxidizer systems. As these
costs indicate, it would be significantly cheaper for a few large
suppliers to produce these devices for those manufacturers with
low light—duty diesel productions. Given the economics, this would
seem likely to occur. Similarly, the credits for reduced main-
tenance (muffler and exhaust pipe) calculated above could also be
averaged across the three engine sizes. The credit for eliminating
the muffler replacement would then be $44 and that for the exhaust
pipe would be $36. Both of these credits are assumed to occur once
in a vehicle’s life, after five years.
Chrysler claimed that EPA had underestimated the costs of this
system. As the revised costs are roughly $40—100 higher than the
original estimates, it would appear that this comment has been
accepted.
BMW estimated a cost of $350. They did not elaborate on the
breakdown of the cost and qualified their estimate because they
were inexperienced in the area. Their engine has 6 cylinders and
their cost estimate should therefore be compared to the revised
estimate for this engine size. The production volume assumed by
BMW, if any, is unknown, however. The estimated cost of the
average trap—oxidizer system for a 6—cylinder engine is $185—221 in
1984. The cost for a small manufacturer such as BMW could be
somewhat higher if they produced their own units. However, without
the details of BMW’s estimate, it is not possible to pinpoint the
reason for the difference.
General Motors estimated the cost of a trap—oxidizer system to
be $470—610. This includes two traps for their larger engines. As
two traps are not projected to be necessary to meet the 1984
standards (see Section II, Control Technology), the cost of the
second trap should not be included. The size of the trap for an
8—cylinder engine has been increased to 7.3 liters, from the 4.26
liters originally estimated to be necessary. Also, all of the
other specific items which General Motors raised have been recon-
ciled in the revised cost estimates. If it is assumed that General
Motors used more typical industry production figures and did not
consider that costs would decrease with time, their estimates
should be compared to a cost of $154—264 per vehicle (fleetwide
average, 1984). Since all of General Motors specific comments have
been addressed, the reason for this final discrepancy cannot be
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determined. No furt er revision can be made to EPA’s revised
estimates without these specific reasons. Thus, the estimated
costs as shown in Table V—1O should remain as they are.
To put this cost in perspective, the cost of a three—way
catalyst system will be estimated. For simplicity, only the cost
of the system for a 6—cylinder engine will be calculated. Again
using Rath and Strong, the cost is shown in Table V—li. The total
cost of a three—way catalyst system using this methodology is
$310 at a production volume of 300,000 units. The comparable
figure for a System IV trap—oxidizer system is $198 from Table
V—9. Thus, a three—way catalyst is about 57% more expensive than a
trap—oxidizer primarily due to noble metal cost.
This estimated cost for a three—way catalyst would not neces-
sarily be the cost of a three—way catalyst on a gasoline—fueled
vehicle. The production volume assumed here was that for light—
duty diesels, 300,000 units, to isolate technological differences.
With a more reasonable production volume of 2,000,000 unitS, a
three—way catalyst would be expected to cost 27 percent less, or
$226.
Comments
Chrysler —— claimed that the trap—oxidizer would required mainte-
nance during the vehicle’s life.
The Council of Wage and Price Stability —— claimed that the trap—
oxidizer would have to be replaced once during the life of the
vehicle.
An a ly S1 S
EPA assumed that trap—oxidizers would require no maintenance
(like current catalysts) and would not require replacement. No
other manufacturer joined Chrysler in challenging the first assump-
tion. However, as the designs of trap—oxidizers are becoming
better known, it seems reasonable to expect some maintenance to be
required. The trap itself should still be maintenance—free, but
the oxidation control system may require periodic adjustment. It
is also possible that a temperature sensor may also need replace-
ment. It is estimated that this type of maintenance would require
about one hour of labor and $10 worth of parts and occur once
throughout the life of the vehicle. At a labor rate of $20 per
hour, the total cost would be $30. This will be assumed to occur
after 5 years of vehicle operation.
The Council based their claim on the belief that a trap
oxidizer is analogous to a muffler which is replaced 2 to 3 times
during a vehicle’s life. EPA does not agree with this analogy.
A muffler costs about $20 (retail price equivalent) and is made out
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Table V—il
Emission Control System Costs per Engine
6—Cylinder Engine with Three—Way Catalyst !I
Modifications for Feedback Carburetor $ 9
Electronic Control Unit $ 6
Three—Way Catalyst $217 2!
Oxygen Sensor $ 3
Stainless Steel Exhaust $ 13 3/
TOTAL $310
1/ “Cost Estimations for Emission Control Related Components!
Systems and Cost Methodology Descriptions,” Rath and Strong for
EPA, March 197$, EPA—460/3—78—002. Production volume of 300,000
units.
2/ Assumes a 250 CID engine with a catalyst volume of 275 cubic
inches, a precious metal loading of 40 g/cubic feet with platinum
and rhodium in a loading ratio of 9:1.
3/ Includes a $7—b credit for the steel exhaust pipe which it
replaces.
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of carbon steel. The trap—oxidizer will :ost over ten times that
and be made of stainless steel. Since today’s catalysts are made
of stainless steel and last the life of the vehicle, EPA does
not foresee any need for replacement of the trap—oxidizer either.
Thus, no replacement cost should be included in the cost analysis.
B. Turbocharging
Comment
Chrysler, the Department of Commerce, the Council of Wage and
Price Stability, Daimler—Benz, Fiat and General Motors —— all
suggested that EPA underestimated the cost of turbocharging a
light—duty diesel.
Analysis
EPA originally estimated the cost of turbocharging to be
$145—$185, depending on the size of the engine. Most of those who
commented in this area submitted cost estimates of their own.
These are shown in Table V—12. In addition, some commenters
presented explanations as to why their estimated costs were higher
than the EPA’s.
General Motors stated that the increased cost was due to the
omission of six items by EPA:
1) Engine modifications (additional oil distribution to
pistons and rods);
2) Revised fuel control (variable control capability);
3) Turbocharger mounting provisions;
4) Exhaust system design change requirement8 to operate the
turbocharger unit;
5) Increased cooling capacity; and
6) Additional assembly.
General Motors did not estimate the cost of any of the six
items. They appeared to agree that EPA adequately estimated the
cost of the turbocharger but omitted the cost of additional items.
Chrysler provided a breakdown of their cost estimate. This
breakdown is shown in Table V—12 along with their total estimated
cost of $325.
Fiat stated that a number of modifications were required in
addition to the turbocharger unit it8elf. A different injection
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Table V—12
Estiirtated Cost of Turbocharging a Light—Duty Diesel
Source Cost
EPA $145—185
General Motors (large engine) $330
Chrysler 325
Turbocharger 243
Oil line and other plumbing 27
New injection pump configuration 9
Manifold and exhaust transition 46
Fiat 300—350
Daimler—Benz 333500 !/
Volkswagen 450—500 2/
!/ Estimated cost to consumer buying whole vehicle. Afterniarket
cost was reported by Daimler—Benz to be $1,000.
2/ Taken from the comments of the Council of Wage and Price Stab-
iLity, who quoted Philip Hutchison of Volkswagen, March 23, 1979.
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system would be necessary along with a boost pressure eleinen . A
waste gate would be required as is a differently—designed p. ston
due to the increased thermal load. Finally, a water/oil heat
exchanger would be required for further cooling of the engine oil.
As in the case with General Motors, no attempt was made to separate
the cost of each of these items.
The only elaboration made on their estimate ($1,000) by
Daimler—Benz is that it is the cost of a turbocharger on a replace-
ment engine. As replacement or aftermarket costs are generally 2
to 3 times the allocated cost to the buyer of the whole vehicle,
their estimate of $1,000 translates to a $333 to $500 cost to the
consumer who buys a turbocharged diesel.
Volkswagen did not elaborate on the breakdown of their cost
est imate.
The original EPA estimate was based on a $90 turbocharger unit
cost to the manufacturer from the supplier. A factor of 1.6 was
used to adjust for mounting, assembly, inventory, etc. In addi-
tion, 10—25% ($15—40) was added for additional plumbing and size
required for 6— and 8—cylinder engines. It is difficult to revise
this estimate using the methodology outlined in the previous
discussion of trap—oxidizer costs because of the lack of detailed
cost information available to EPA in this area. The manufacturers’
estimates do not include the necessary detail to include them
easily into such a methodology. Fortunately, the importance of
the cost of .turbocharging has greatly diminished as EPA no longer
expects turbocharging to be widely used as a particulate control
technique (see Section II, Technology). However, some effort will
still be made to reconcile EPA’s original estimate with those of
the manufacturers.
The cost of the turbocharger itself from the vendor was $90 in
1978.11/ None of the coumtents have given sufficient evidence for
not accepting this figure. As this is a 1978 cost, it should be
adjusted for one year’s inflation (8%) to $97. The cost of bolting
and connecting the turbocharger to the engine should be minimal,
about $1 per engine. This is supported by vehicle assembly costs
for manifolds and catalysts, which average about $0.20 per vehicle
at the vendor level.12/ Thus, at the vendor level, the turbo-
charger unit should cost $98. To convert this to a retail cost,
it needs to be increased by a factor of 1.277 (see part A, Trap—
Oxidizers in this section). At the corporate level, the cost would
then be $125 per vehicle. As the original $90 turbocharger cost
11/ “Ford Buying Garrett Turbos,” Automotive News, April 17, 1978.
12/ “Cost Estimations for Emission Control Related Components!
Systems and Cost Methodology Description,” R.ath and Strong for EPA,
March 1978, EPA 460/3—78—002.
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was for a 4—cylinder engine, some allowance should be made for
higher costs for larger engines. A factor of 1.15 will again be
used for 6—cylinder engines, and 1.25 will be used for 8—cylinder
engines. This results in costs of $144 and $156 per turbocharger
for 6— and 8—cylinder engines, respectively.
With respect to the cost of engine modifications necessary to
accomodate the turbocharger, little data is available. General
Motors listed some modifications, but did not provide the separate
cost of any of them. Chrysler presented essentially the same list
of necessary modifications, but did include their individual costs.
As EPA agrees that these modifications (see Table V—12) are neces-
sary and no other cost data are available except that submitted
by Chrysler, the Chrysler data will be used subsequently. It will
be assumed that the Chrysler costs include overhead and profit.
Thus, the cost of oil lines and other plumbing, a new injection
pump configuration, and modifications to the manifolds and exhaust
systems should cost $82 per engine.
The total cost of turbocharging an engine is then $207 for
a 4—cylinder engine, $226 for a 6—cylinder engine, and $238
for an 8—cylinder engine. While these costs are still lower than
those submitted by the manufactures, the lack of detail of the
submitted estimates prevents them from being used to further
adjust the above cost estimates.
Comment
The Council of Wage and Price Stability —— claimed that the turbo-
charger would need to be replaced once during the life of the
vehicle.
Analysis
The Council was the only organization to bring up this point.
None of the auto manufacturers disagreed with EPA that the turbo-
charger would last the Life of the vehicle. It is actually un-
likely that a manufacturer could sell a turbocharged vehicle if
their customers knew that they would have to pay at least $500
(aftermarket price) for a new turbocharger after only 50,000 miles.
Also, there is no indication from the maintenance schedules of
current turbocharged light—duty vehicles (gasoline or diesel) that
the turbochargers will not last the life of the vehicle.
The logic used by the Council was that turbochargers are
analogous to fuel and water pumps, which typically require replace-
ment once during the life of the vehicle. However, there is not
much in common between the devices, except that all are fluid
pumps. Fuel and water pumps generally cost less than $20 (retail
price equivalent) and their construction, durability, and quality
reflect their cost. A turbocharger costs $270, more than 10 times
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more than the other two pumps. Its quality and durability are
reflected by its cost. Thus, EPA should hold to its position that
turbochargers will last the entire life of the vehicle.
Comment
Chrysler and General Motors —— stated that the fuel economy benefit
of turbocharging was only 4%.
Volkswagen —— stated that turbocharging would increase fuel economy
lO7 .
Ford and the Department of Energy —— agreed with EPA that turbo—
charging could increase fuel economy 8% if accompanied by adjust—
merits in the axle ratio.
Fiat —— stated that turbocharging could increase fuel economy
particularly if drive line parameters were optimized.
Anal y s is
[ c is obvious from the above comments that there is not total
agreement on the effect of turbocharging on fuel economy. To
determine the best estimate of this effect, it will be necessary to
analyze the data made available by these manufactaurers. The
manufacturers will be discussed in order of their estimates,
beginning with the lowest.
Chrysler did not support their estimate with any test data of
their own. They did use a computer model to simulate a turbo—
charged diesel with drive line optimization. The results were a 3%
increase in fuel economy for a large vehicle and a 6% increase for
a small vehicle. The latter vehicle configuration included a
fifth—gear so extreme that adequate driveabi].ity was questionable.
They also quote EPA ’s data on two Mercedes vehicles showing a 5.5%
fuel economy increase. Chrysler counters EPA ’s data on two Volks-
wagen vehicles (24% fuel economy increase) by quoting data which
Volkswagen submitted to the Department of Transportation showing a
2% decrease in fuel economy with turbocharging. This last modifi-
cation, however, did not increase the maximum fuel rate, nor
include any changes to the drive line, and is really riot indicative
of a turbocharged vehicle as it would be marketed. It also con-
flicts with the data Volkswagen themselves submitted which will be
shown below.
General Motors provided some test results in support of their
estimate. The first set of tests examined the effect of adding a
turbocharger to an engine with no changes to the drive train of the
vehicle. These four vehicles averaged a 3% decrease in fuel
economy with turbocharging, but also averaged a 30% decrease in
O-60 mph acceleration time. Thus, the performance of the turbo—
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charged vehicle was greatly improved over those equipped with
naturally—aspirated engines.
A second data set of three vehicle sets examined the effect of
a turbocharger without modifying either the maximum fuel delivery
or the drive train. As would be expected, due to the increased
backpressure caused by the turbocharger, the fuel economy decreased
6% with turbocharging. Since vehicles would not likely be marketed
with these constraints, this data is of questionable value in this
analysis.
A third set consisted of a single test of a vehicle equipped
with the naturally—aspirated 5.7—liter diesel and a single test of
the same type of vehicle equipped with a turbocharged 4.3—liter
diesel. The fuel economy of the turbocharged version decreased
0.5% while 0—60 mph acceleration time improved 6.5%.
The last set of data examined the effect of drive train
modifications on the fuel economy of one of the turbocharged
vehicles which was tested as part of the first data set. A de-
crease in rear axle ratio from 4.15 to 3.34 increased fuel economy
4.5 miles per gallon or 13.5%. The data from this data set and
that from the first data set is shown in Table V—l3. The first
step of adding the turbocharger showed a 7% decrease in fuel
economy with a 26% decrease in 0—60 mph acceleration time. With
the additional change to a 3.34 axle ratio, however, overall fuel
economy improved 6% while the 0—60 mph acceleration time still
decreased 10%. General Motors identifies this as a reasonable
change in axle ratio.
Fiat submitted both data and modeling results indicating the
effect of turbocharging on fuel economy. Their data is shown in
Table V—14. The actual data compares a naturally—aspirated engine
with an axle ratio of 3.2 (standard for that model) to a turbo—
charged engine with an axle ratio of 2.6. The urbocharged version
gave a 5% increase in fuel economy with a 22% decrease in 0—60 mph
acceleration time. The computer model predicted an % increase in
fuel economy. The model was then used to predict an axle ratio
reduction to 2.4 for the turbocharged version, which still provided
much improved performance over the naturally—aspirated version.
This change in axle ratio increased fuel economy an additional 6%
or 2.1 miles per gallon.
To obtain the combined effect of turbocharging and axle ratio,
the actual data and modeling must be combined. Even though the
actual data only consisted of one test, it will be used instead of
the modeling results (for the turbocharging step). From Table V—14
then, turbocharging and a decrease in axle ratio to 2.6 improved
fuel economy 1.7 miles per gallon. A further decrease in axle
ratio to 2.4 improved fuel economy 2.1 miles per gallon. Overall,
fuel economy improved 3.8 miles per gallon or 11%, while perfor-
mance was still improved.
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Table V—13
The Effects of Turbocharging and Rear—Axle Ratio
on Fuel Economy and Performance —
Pre X—Car with Opel Diesel
Composite Acceleration Time
Engine Rear Fuel Economy 0—60 mph
Configuration Axle Ratio ( mpg) ( seconds )
Naturally—Aspirated 4.15 35.7 19.9
Turbocharged 4.15 33.3 14.7
3.74 34.6 17.2
3.34 37.8 18.0
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Table V—14
Effects of Turbocharging and Axle Ratio
on Fuel Economy and Performance
!/ Standing start.
2/ Standard configuration.
3/ Actual data.
Fiat 131 — Modeling Results
3.2 2/ 35.0
(34.6) 3/
Engine
Configuration
Rear
Axle
Ratio
Composite
Acceleration
Fuel
Time
Acceleration
Economy
(mpg)
0—60 mph
(seconds)
Time 1 Kin
(seconds)
1/
2.8 37.9
3.0 36.4
Naturally—As pirated
Turbocharged
2.4
2.6
2.8
18.1 39.6
17.9 39.5
17.7 39.4
13.9 36.1
13.8 35.9
13.7 35.9
39.8
37 . 7
(36.3) !/
35.7
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Ford presented one data set from their own testing which
compared the fuel economy effect of turbocharging without a change
in the axle ratio. These tests on an Opel. showed a 2% increase in
fuel economy while performance was not measured. They quote
Volkswagen data on a Rabbit showing a 10% increase in fuel economy
with turbocharging and a decrease in axle ratio from 3.9 to 3.6.
They also quote the Fiat data, which has already been discussed.
Finally, Ford quotes a study performed by Ricardo on a Mercedes—
Benz 300D. The fuel. economy decreased 7.5% with no change in the
axle ratio. As the commercial Mercedes—Benz 300SD has consistently
shown 5—6% better fuel economy than the 300D with a heavier vehicle
and improved performance, this last result appears anomolous and
will not be considered any further.
The Department of Energy submitted no data to substantiate
their estimate. They only stated that they had examined the data
available at that time, which was likely most of what is being
shown here. They did add the qualification to their 8% estimate
that it would include a weight reduction due to the use of a
smaller (though more powerful) turbocharged engine.
Finally, Volkswagen did not submit any data in addition to
that quoted by Ford.
To summarize all this data, it will be important to be consis-
tent in the hardware changes which are affecting the fuel economy.
Because a turbocharged diesel can be equipped with a lower axle
ratio to improve fuel economy, without a degradation of performance
below that of the naturally—aspirated engine, that is the configur-
ation that will be compared. It is recognized that the axle ratio
does not have to be lowered, and that a performance improvement can
result. However, it is difficult to put a value on performance so
the maximum fuel economy case is most appropriate for this discus-
sion. Table V—iS shows the estimates of the various groups and the
results of their data.
The single datum, representing the lower limit of the range of
General Motors’ data, shows no improvement with a smaller turbo—
charged engine at equal performance and appears quite suspect in
the midst of all of the other data. At the same time, the largest
improvements have all occured on small vehicles (VW, Fiat). Noting
that the improvement on a Mercedes 300D (4000 pounds) was 5.5%, a
reasonable average should be between 5.5% and 10—liZ. A simple
arithmetic average would be 7.75—8.25% or about 8%. Since this was
EPA’s original estimate, no change should be required in this area.
Comment
The Council of Wage and Price Stability —— suggested that EPA use a
57. discount rate for fuel costs rather than not discounting these
costs at all.
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Table V—15
Fuel Economy Improvements Due to Turbocharging
Organization Estimate Result of Data
Chrysler 4% 3 — 6%
General Motors 0 — 6%
Fiat 11%
Department of Energy 8%
Ford 8%
Volkswagen 10% 10%
1/ Quote of Fiat and Volkswagen data.
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The Department of Commerce —— suggested that EPA’s projection that
fuel prices would rise 10% faster than the general price index was
‘draconian’.
An a ly Si S
A 10% discount rate was used in the Draft Regulatory Analysis
for all costs and savings except those involving petroleum—based
fuel; in this case, diesel fuel. It was projected that diesel fuel
prices would rise 10% faster than the general price index per year,
and to account for this , no discount rate was used.
Adjusting discount rates is a shorthand technique to account
for cases where inflation is not expected to occur equally for
every item under consideration. A technique which is perhaps more
straightforward, but which requires more computation would be to
inflate the fuel costs or savings first, by the difference between
the projected inflation rate for fuel and that for all other goods,
and then discount all costs by the same discount rate, in this case
10%. To illustrate the difference between the two techniques, an
example is given below.
Example: The annual inflation rate of most goods is assumed
to be 5% over the next 15 years. Fuel prices, however, are
assumed to increase 12% per year over the next 15 years. A man
owns a tractor and expects to have maintenance fees of $100 per
year (1979 dollars) in 1979, 1980, and 1981. He also expects to
spend $600 per year for fuel (1979 dollars) over the same three
years. He desires to determine the present value (1979) of these
expenditures. A 10% discount rate will be used. The maintenance
costs can be discounted directly and added to receive the total,
$273.55. The fuel costs should first be inflated to $600 (1979),
$640 (1980) and $682.67 (1981) using the ratio of the inflation
rates of fuel and other items (1.12/1.05). These inflated costs
can then be discounted back to 1979 and added to equal $1,746.01.
Adding the maintenance and fuel costs yields $2,019.56.
The shorthand technique would combine the excess inflation
rate of fuel and the discount rate to arrive at a special discount
rate for fuel. This can be done in one of a few ways. For com-
plete accuracy, the discount rate, plus one (1.10) can be divided
by the inflation rate for fuel plus one (1.12) and then multiplied
by the general inflation plus one (1.05). Subtracting one yields
a special discount rate for fuel of 3.125%. Now calculating the
present value again, the total maintenance costs remain at $273.55.
The fuel costs of $600 in 1979, 1980, and 1981 are now discounted
at a rate of 3.125%. The result is a present value of total fuel
costs of $1,746.01, or the same value as that calculated above.
An ever simpler method, though slightly less accurate, is to
subtract the excess inflation rate (determined by subtracting the
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general inflation rate from the inflation rate for fuel) (7%) from
the discount rate (10%). This method yields a special discount
rate of 3%. The difference between the two shorthand techniques is
only 0.12% per year in this case (1.03125/1.03). For the purposes
of this analysis and the Regulatory Analysis, the latter shorthand
technique wiLL be used.
The Council of Wage and Price Stability believed that a 10%
difference between the inflation rate of diesel fuel and the
general inflation race was too high. They performed an analysis of
these two inflation rates between February 1973 and February 1979.
This analysis showed the price of diesel fuel, to be rising about 3%
faster than the general price index (10.8% compared to 7.9%). The
Department of Commerce simply stated that it was “draconian” to
assume chat the price of diesel fuel would rise 10% faster than the
general price index, but gave no support to their statement.
The Council’s analysis and recommendation appears to be very
reasonable. Since the conclusion of chat analysis, however, the
price of diesel fuel has risen from $0.527 per gallon (February 5,
1979) to $0.869 per gallon (June 25, 1979).13/ Incorporating this
time period into the Council’s analysis results in a 19.0% annual
compounded inflation rate. If a 1% per month inflation rate for
the general price index since February 1979 is assumed, the annual
inflation rate for the general price index between February 1973,
and July 1979 is 8.2%. The difference between inflation races now
becomes 10.0% (1.19/1.082). This is an increase of over 7% av-
eraged over the 6.5—year period due to the increase in fuel prices
over the last five months.
From their analysis, the Council had suggested a 5% difference
between the general discount rate and that for fuel. From the
results of the Last paragraph, the 10% difference may be justified
after all. However, the latter analysis does include a period of
extremely—high inflation of fuel costs right at the end of the
period in question. This has a tendency to overemphasize that
period if the trend does not continue. It is unlikely that the
Council did not foresee the most recent price increases, but still
believed that over the long term a 5% difference would be the most
accurate. Given that it is a compromise between the 2.7% dif-
ference through February 1979 and the 10% difference through July
1979, EPA will accept their suggestion. The Regulatory Analysis
should use a 5% discount rate for fuel costs and a 10% discount
rate for all other costs.
C. Other Engine Modifications
13/ Barbara O’Connor, Interstate Commerce CommissiOn, June 27,
1979.
hi
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Comment
General Motors —— claimed that EPA’s estimate of $1 per vehicle
for minor combustion chamber modifications is very optimistic.
By minor combustion chamber modifications, EPA means small
changes to the chamber geometry, nozzle configuration, piston
configuration, etc. None of these changes should require the
addition of any items or hardware to the engine, only the redesign
of existing items. As such, EPA does not expect the cost of the
redesigned item to be any more than the existing item, with the
exception of the research, development and tooling costs involved
in making the change. These costs (per vehicle) are very dependent
on the number of years over which they are amortized. It would be
convenient to amortize the cost over the three model years which
have to meet the 0.6 gram per mile standard. Even though these
engine modifications will likely continue past 1983, it will
simplify the cost calculations to have the costs paid off by the
time the second standard becomes effective.
With two or three year’s production over which to amortize the
costs, the cost per vehicle should be no more than $10. This would
provide General Motors over $6 to 9 million in 1980 for research,
development, and retooling, depending upon the implementation dates
of the standards and assuming a discount rate of 10 percent and
that funds obtained from a model year’s sales are not available
until December 31 of that year. The sales figures used were those
outlined in part c) of the Environmental Impact section of this
document with an annual increase in sales assumed to be 2% over
1978 sales.
As General Motors did not present an estimate of the cost
themselves, the $10 per vehicle estimated in the above paragraph
should be used in the Regulatory Analysis.
D. Test Equipment and Testi &
General Motors —— “Facility modification costs are five times
higher than predicted by EPA.. .GM’s estimated costs are as follows:
Facilities Modification Costs
CFV—Tunnet System $62,500
600 cfm CFV $53,000
Dilute Exhaust System $ 9,500
Particulate Sample System 20,000
• Computer System Modification 95,000
Gaseous System Modifications 13,000
Cost per Site $190,500
Particulate Weighing Facility 42,000
and Equipment
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Additional Cost Per Facility 42,000
Cost to General Motors — $5,118,000”
24 Sites at 13 Facilities
An a ly s i.s
A close review of the site cost numbers would indicate General
Motors’ intent to highly automate their particulate sample system.
This is especially apparent from their cost estimate of the parti-
culate sample system ($20,000) and the computer system modification
($95,000). This is further confirmed by their proposal to use a
regulated or servo—controlled particulate sample system. Such
sophisticated automation and control will quickly add cost to a
test site, and are really discretionary costs. Further, there is
no justification for the $13,000 gaseous system modification to be
attributed to particulate—related modifications.
EPA cost estimates were for a more basic system without
substantial automation. Using this philosophy, the General Motors
cost estimates would reduce to the following:
Facilities Modification Costs
CFV—Tunnel System $62,500
600 cfm CFV $53,000
Dilute Exhaust System $ 9,500
Particulate Sample System 10,000
• Computer System Modification ——
• Gaseous System Modifications ——
Cost Per Site $ 72,500
• Particulate Weighing Facility 42,000
Additional Cost Per Facility 42,000
Cost to General Motors — $2,286,000
24 Sites at 13 Facilities
These revised per—site costs and per—facility costs are more in
line with EPA’s own updated cost estimates. These updated cost
estimates are as follows:
CVS (600 cfm) including $38,100
heat exchanger plus
• Dilution Tunnel 10,000
Particulate Sample System 7,000
Cost Per Site $55,100
• Microgram Balance 10,000
• Weighing Chamber 20,000
Cost Per Facility $30,000
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EPA concludes from these revised and updated cost estimates that
while General Motors may intend to spend $190,500 for each site and
$42,000 for each facility, much of the expense is discretionary.
General Motors could only make these expenditures because the
manpower requirements for testing would be reduced to the point
that overall costs would be minimized. Over a longer period of
time, an automated system will actually lower the overall cost of
testing. However, this savings has not been reflected in any of
the above equipment costs. If GM does not believe these extra
expenditures will not pay for themselves eventually, EPA can only
assume they will not actually proceed with the extra features.
Comment
International Harvester —— “EPA’s Draft Regulatory Analysis dated
December 22, 1978, indicates that these regulations will add
$562.69 to the cost of our diesel—powered Scout as follows:
1981—82 1983—85
One Durability Vehicle $156,000 $156,000
Three Data Vehicles 63,000 63,000
Test Facility 42,300 _______
$261,300 $219,000
Cost Per Unit (Five Years) $90.10 44.69
Hardware Costs 1981 180.00 180.00
1983 —— 338.00
Total $270.10 $562.69 “
International Harvester has also requested that assigned deteriora-
tion factors (DFs) be made available for exhaust particulates for
low—volume manufacturers.
An a ly Si. S
The comment on assigned deterioration factors for low—volume
manufacturers has been included in this section because it is
coupled to International Harvester’s overall cost of testing
through their estimate of $156,000 for one durability vehicle in
the table.
International Harvester, in the past, has applied for and
received assigned deterioration factors (DFs) for gaseous emissions
under § 8 6.078—24(e)(4) and §86.078—24(f). Because of the general
applicability of §86.078—24 to all regulated exhaust emissions, it
was intended that particulate emissions would also be handled under
this section. No proposal has been made to revise this section.
Hence, International Harvester, or any other manufacturer should be
able to continue to apply for assigned DFs under §86.078—24.
It should be noted that International Harvester also requested
that EPA consider revising the definition of a low—volume manufac—
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turer from one that estimates a production volume of less than
2,000 units to one that estimates production of less than 10,000
units. This request is beyond the scope of the light—duty diesel
NPRN and therefore cannot be treated here. This request will be
considered when EPA reviews these provisions of the regulations.
As implied earlier, the requirement to run a durability vehicle is
not connected to these particulate regulations. If IHC’s diesel
Scout production exceeded 2,000 units per year, the requirement to
run a durability vehicle would exist whether or not this particu-
late regulation was promulgated. Thus, the cost of running a
durability vehicle should not be connected with this regulation.
The only exception could be the first year of the second
standard, 1984, when a change in the particulate standard might
necessitate the running of a durability vehicle. Even this re-
quirement hinges on IHC’s diesel Scout production being over 2,000
units per year. As can be deduced from IHC’s calculations above,
they have used a 3—year production total (1983—85) of 4,900. This
total should not result in a requirement to run a durability
vehicle and the $156,000 cost should not be included. In Part A of
this section, however, EPA did project INC to produce about 8,000
vehicles over this 3—year period, which would require a durability
vehicle. However, the cost would then be spread out over more
vehicles and the cost per vehicle would be less. The certification
and test facility costs under both these situations are shown
below. The costs being used are those from the NPRN unless modi-
fied in previous sections.
Low Sales High Sales
1982—83
Three Data Vehicles 63,000 63,000
Test Facility 85,000 85,000
1984—85
One Durability Vehicle — — 156,000
Three Data Vehicles 63,000 63 ,
Total Cost $211,000 $367,000
Total Sales (5 years) 8,000 21,000
Cost Per Unit 26 17
As can be seen, neither of these costs is very high, likely being
less than 0.5 percent of the price of a Scout. After the 5—year
payout period is over, these costs will decrease to zero.
Further, the $338.00 that IHC attributed to 1983 hardware
costs is really the total of the 1981 and 1983 hardware costs.
The 1983 line should have read $158.00 (estimated for trap oxi-
dizer) and IHC’s hardware costs become the same as those for the
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other manufacturers. From the analysis in the previous three parts
of this section, it is evident that all of the projected costs of
the two standards should be adjusted for the final analysis.
However, this does not change the outcome of the analysis above.
I}IC’s costs per vehicle should be very close to those for the other
manufacturers. The only exception could be the trap—oxidizer cost
(see Part A of this section) if IHC decided to produce its own
traps. However, given the economics and that IHC does not produce
its own catalysts for its gasoline engines, which have a higher
sales volume, this is unlikely. Thus, EPA concludes that Inter-
national Harvester has substantially overestimated the additional
cost to the Scout and that their costs are not out of line with
those of other manufacturers.
E. Cost Effectiveness
Comment
The Council of Wage and Price Stabilitl —— stated that the marginal
cost effectiveness of the 1983 standards appears to be too high
compared to that of other control techniques.
Analysis
The Council submitted the following table (Table V—l6) showing
the marginal costs of control of the diesel particulate standards
and other control strategies. As can be seen, the 1983 diesel
particulate standard is more expensive per ton of particulate
reduced than all the others.
EPA believes that the past practice of using a simple cost per
mass of pollutant reduced is insufficient to accurately discrimi-
nate between choices of control strategies. As the Council’s table
shows, it is getting expensive to further control particulate
emissions. EPA needs to ensure that its programs are positively
affecting the health f the nation. To do this, we need to ensure
that: (1) ambient pollutant levels being breathed by people are
being reduced, and (2) we are controlling emissions which are
harmful to health. The simple dollar per ton figures will not
allow this to be done.
First, a measure is needed to determine the impact of a
regulation on those people living and working in areas affected.
This measure should include the number of people affected and the
reduction in ambient pollutant levels experienced by those people.
The height of the stack or exhaust coupled with the size and
density of the particles will affect how long these particles
remain aloft and available for inhalation. The height of the stack
or exhaust will also affect the impact of that source on air
quality. These factors need to be taken into account, but the
question remains of how to do it. Two possible methods will be
outlined below.
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Table V—16
Marginal Costs per Metric Ton of
Controlling Particulates
(1978 dollars)
Diesel Light—Duty Vehicles
1981 Standards: EPA’s estimate $ —160
CWPS estimate #1 $1,720
CWPS estimate #2 $4,470
1983 Standards; EPA’s estimate $3,200
CWPS estimate #1 $5,500
CWPS estimate #2 $7,650
Electric Utilities 1/
NSPS, Eastern Coal: 100 MW Steam Electric $1,931
1,100 MW Steam Electric $2,203
Medit.un—SiZe Industrial Boiler, NSPS 2/ $6141,199
Sewage Incinerators, NSPS 3/ $1,3352 ,205
Electric Arc Furnaces, NSPS 3/ $2,095
Kraft Pulp Mills, NSPS 4/:
Recovery Furnace $385781
Smelt Tank $259344
Lime Kilns, NSPS 5/:
New $3,120
Retrofit $1,750
1/ PEDCO, “Particulate and Sulfur Dioxide Emission Control
Costs For Large Coal—Fired Boilers,” Reported prepared for EPA,
OAWM, OAQPS, Research Triangle Park, N.C., February 1978.
2/ Industrial Gas Cleaning Institute, “Particulate Emission
Control Costs for Intermediate—Sized Boilers,” Report prepared for
EPA, SASD, EAB, Research Triangle Par, N.D., February 1977.
3/ “Draft Regulatory Analysis,” p. 88
4/ EPA, OAWM, OAQPS, “Standards Support and Environmental Impact
Statement, Vol. I: Proposed Standards of Performance for Kraft
Pulp MIlls,” September 1976.
5/ EPA, OAWM, OAQPS, “Standards Support and Environmental Impact
Statement, Vol. I: Proposed Standards of Performance for Lime
Manufacturing Plants,” April 1977.
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The first method is an ideal one. It assumes that all neces-
sary information is available. While this is never the case, this
method will serve to outline the important features of calcula-
ting a true cost effectiveness for the more practical method to
follow. The primary principle to keep in mind is that we should be
measuring an improvement in people’s living and working environ-
ment. The state of that environment (for our purposes) is deter-
mined by the ambient concentration of harmful pollutants which
exist there. From this basic premise, a good measurement of the
effectiveness of a regulation can be determined. Assuming lin-
earity holds in the above statements, a figure such as person—
concentrations would fulfill the requirements. An illustra-
tive example is given below.
Example: Regulation A will reduce ambient TSP levels by 5
micrograms per cubic meter (annual geometric mean), in areas
containing one million people. The effectiveness of this regu-
lation would be 5.0 million person_micrograms per cubic meter (1
million person x 5 micrograms per cubic meter).
This type of analysis would require a good population exposure
data base, both before and after regulation to both the source in
question, and to TSP levels from other sources in aggregate. Since
this information is rarely available, the question is now how to
best estimate it, using the information that is available.
This leads us to the second method, which is practical, but
approximate. Three factors must be accounted for; source location,
height and particle size. Source location is important because it
determines how many people are exposed to the source’s emissions.
Source height is similarly important since it determines the
magnitude of the impact on ambient levels. ParticLe size is
important since it determines how long a particle stays aloft
where it can be breathed. All of these factors could then be
applied to emission reductions, which alone are not a good measure
of air quality benefit.
After accounting for these factors, the second step is to
adjust for particle characteristics which affect health. The bulk
of health effects work now shows that it is the inhalable particles
(diameter less than 15 micrometers) that affect health, with the
fine particles (less than 2.5 micrometerS diameter) probably the
most dangerous.14/ Given this knowledge, it is not difficult to
see that reducing the ambient level of particulate larger than 15
micrometers will not improve public health nearly as much as an
equivalent reduction of inhalable or fine particulate.
14/ Miller, Frederick J., et.al. , “Size Considerations for Estab-
lishing a Standard for Inhalable Particles,” JAPCA , Vol. 29, No. 6,
June 1979, pp. 610—615.
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It is true that the NAAQS for particulate matter is based on
measurements of TSP, but this does not affect the results of the
above argument. If we know that the fine and inhalable fractions
cause the health problems, then bringing the entire U.S. into
compliance with the NAAQS by simply reducing levels of particulate
larger than 15 micrometers would be complyng with the letter of the
law, while providing little, if any, benefit to public health.
Thus, the effectiveness of a control strategy should be measured
only on an inhalable or fine particulate basis. There is little
danger that a disproportionate share of inhalable particulate will
be controlled with respect to TSP since the larger particles are
almost always the easiest to control, and will be reduced with the
smaller ones.
Returning to the comments of the Council of Wage and Price
Stability, their table shows the marginal Cost effectiveness of
a number of particulate standards. As they have added the marginal
costs of a few more standards to those that were included in the
Draft Regulatory Analysis, they have improved our ability to
compare the light—duty particulate standards to other regulations.
As they have not incorporated the factors discussed above into
their submittal, the table cannot be used as it now stands to
compare regulations. The adjustment factors mentioned above
will need to be incorporated before any comparison can be made.
Since it is one of the primary purposes of the Regulatory
Analysis to perform such comparisons, the adjustment of these
values should be left to that document. There, a new cost effec-
tiveness of the final diesel standards should also be calculated,
reflecting the comments contained in this document.
Comment
The Council on Wage and Price Stability —— presented a much cheaper
alternative control strategy than diesel particulate regulations:
more frequent and more thorough cleaning of city streets.
Analysis
The Council cites two reports when discussing this alternative
in their comments to the EPA.15/,16/ When calculating the cost
effectiveness of this alternative, the Council assumes that clean-
ing streets twice as often will reduce emissions by 50%. A search
of these two reports shows that neither one discusses the effect of
cleaning on emissions. It is acknowledged that to determine a cost
effectiveness that would be comparable to the cost effectiveness of
15/ “Guidelines for Development of Control strategies in Areas
with Fugitive Dust Problems,” U.S. EPA, October 1977, EPA 450/277
029.
16/ “Control of Reentrained Dust from Paved Streets,” PEDCo
Environmental, July 1977, EPA 907/977007.
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other strategies listed in the draft Regulatory Analysis, the
Council was likely forced to make this type of assumption. The
effect on emissions, however, could be as low as zero which
will be shown below.
.
The PEDCo study,17/ included field studies of five cleaning
techniques. In the “Summary of Control Measure Evaluations,” the
report states:
The relationship between cleaning and subsequent emission
rates appears to be complex: emission rates are not
directly related to the percent of street surface
loadings removed from the traffic lanes (just as emission
rates were not found to be closely related to the street
surface loadings). Also, the street cleaning studies
with streetside samplers tended to show a positive effect
from cleaning operations, while those using regional.
network samplers in general failed to show an impact from
street cleaning.
It appears that only flushing (with water) had any consistent
positive effect, but then only on the day of flushing. No effect
was found on the day after cleaning. The reduction on the day of
cleaning averaged 16 microgramS per cubic meter for the two studies
in which this was effective. From the above paragraph, this is
taken to be a streetside effect, and not a regional effect.
Flushing was ineffective in two other studies.
Flushing has an undesirable side effect of increasing the
amount of material carried into the sewer, increasing the load on
the local water treatment plant. it would seem reasonable to
estimate that any reduction in emissions to the atmosphere would
result in an equal increase in water pollution. The study did not
deem this insignificant. Attempts to sweep the gutters after
flushing were ineffective.
The latest EPA report in the area confirms these findings.17/
In its summary on relative effectiveness, it rates street cleaning
poor and costly. The earlier EPA studyl5/ acknowledges that
intuitively this technique should reduce reentrained dust, but up
to now is still unproven. It advises caution be taken before
undertaking any studies and that small pilot—scale projects be
tested in each city considering this technique to accurately
predict its effect. It also mentions that the interest and full
support of the local public works department is necessary if any
street cleaning problem is to be successful.
17/ “Particulate Control for Fugitive Dust,” U.S. EPA, April 1978,
EPA—600/7—78-07 1 , pps. 28 & 51.
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In summary, it appears that there are still significant
problems with street cleaning as a control technique. Its effect
on regional TSP concentrations is doubtful. At the same time, there
is evidence that if performed correctly in certain areas, it could
reduce roadside concentrations significantly. Any decision to move
ahead in this area would have to be made at the state and local
levels. As such, it is outside of the realm of this regulation or
any other nationwide EPA regulation. Due to its lack of effect on a
regional scale, and other associated problems, it is not an effec-
tive alternative to this rulemaking action, and will not be con-
sidered further.
E. Recommendations
The following changes should be made as a result of comments
on the economic impact of this proposed regulation:
1) The estimated cost of a trap—oxidizer should be increased
to $189—224 (1984) and $128—152 (1988) from the original estimate
of $114—157, plus a $30 maintenance fee and an $80 maintenance
credit (exhaust pipe and muffler) occurring after 5 years.
2) The estimated cost of turbocharging should be increased
to $207—238 per vehicle from $145—185 per vehicle, and the fuel
economy improvement due to turbocharging should remaifl unchanged
at 8 percent.
3) A 5 percent discount rate should be used for fuel costs,
and a 10 percent discount rate for all other costs.
4) The estimated cost of minor combustion chamber tnodif i—
cations should be raised to $10 per vehicle, from $1 per vehicle.
5) The estimated cost of test equipment modifications should
be increased to $55,000 per test cell plus $30,000 per facility,
from $40,000 per test cell plus $8,000 per facility.
6) The simple dollar per ton measure of cost effectiveness
has been shown to be inadequate for the area of particulate emis-
sions. A comparison of the cost effectiveness of appropriate
alternative strategies should be performed in the Regulatory
Analysis using more sophisticated techniques.
7) Street cleaning should be rejected as a cost—effective
alternative control strategy because of questionable effectiveness
and cost on a regional scale.
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VI. Alternative Regulatory Approaches
In the NPRM, EPA invited interested parties to comment on
alternative regulatory approaches.
A. Smoke Standards
Comment
American Motors — — “Because of the complexity, cost, and leadtime
associated with this procedure, other alternative methods should be
explored such as smokemeters which could serve as an interim stan-
dard and satisfy the CAA requirements for the 1981 modeL year.”
Analysis
The Clean Air Act explicitly mandated control of particulate
emissions. While smoke standards would likely result in some
control of diesel particulate, EPA does not consider smoke opacity
to be a good indicator of particulate emissions. The smoke opacity
of an exhaust scream is primarily a function of the optical prop-
erties of the particulate, rather than of the mass or quantity of
the particles in the exhaust stream. It has been shown, for
example, that while particulate is emitted under all engine op-
erating conditions, smoke opacity is generally very low except
under full load conditions. Smoke opacity is a measure of the
visible particulate, and as such is appropriate for a standard
based on aesthetic considerations. It is not a valid parameter for
a standard based on total particulate emissions and public health
considerations.
B. Corporate Average particulate Standard (CAPS )
Comments
General Motors — — “ [ tin response to the EPA invitation to address
alternate particulate standard concepts, General Motors has de-
veloped a Corporate Average Particulate Standard (CAPS) concept.
We believe this concept has the potential for providing the bene-
fits of the diesel engine, reasonably controlling diesel particu-
late emissions, and being responsive to the legislative and regu-
latory requirements while properly considering technological
feasibility and manufacturer capabilities. This CAPS results in a
sequence of particulate standards based on the average level of
particulate emissions of a manufacturer’s total-both gasoline and
diesel—powered——light—duty car and truck production. Although this
standard—setting concept is markedly different than that proposed
by EPA, such a concept is currently used in establishing fuel
economy standards, so it is not new to government regulation....
[ T]he basic objective of the particulate standards is to prevent
any deterioration in the mobile source contribution to total
suspended particulates.. .The resulting CAPS levels are shown below:
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Year CAPS Level
1981 0.2 gpm
1983 0.1 gpm
1985 0.07 gpm
1987 0.05 gpm
In addition to these CAPS levels, a maximum permissible particulate
emission Level of 1 gpm from any individual diesel engine was also
made a part of the CAPS requirements. . . . In summary, the CAPS
concept provides a number of major benefits. First, the air
quality impacts would be reliably controlled, since the CAPS level
would limit the total particulate emission levels to the atmos-
phere. This is a distinct improvement in long—term performance of
the standard over the individual engine standards proposed by EPA.
Second, CAPS would provide each manufacturer flexibility in deter-
mining what mix of diesel engine sizes can be produced, as well as
what percentage of total production can be diesel engines. . . .Third,
CAPS provides a strong incentive for diesel manufacturers to
develop better particulate emission controls, since successful
development would allow increased sales of diesels with the result-
ing increase in fuel efficiency. Fourth, the CAPS concept is
enforceable utilizing the basic structure of EPA enforcement
regulations now in place. Only minor administrative modifications
would be required to perform the enforcement operations in an
effective manner.”
Council on Wage and Price Stability —— “This [ EPA] form of standard
has the following major drawback: if a manufacturer produces
different diesel models which have different costs of meeting an
established standard, this form does not permit any trading—off of
Low cost means of control against high cost means of control across
different vehicles... .Regardless of the level of stringency chosen
for the diesel particulate standard (in terms of grams per mile), a
sales—weighted average approach means lower costs of compliance as
compared to the EPA’S proposed approach; the 5 i s_weight average
approach would always be more cost—effective. . . .Our reconunended
sales—weighted approach is currently applied in the automotive fuel
economy area; it is also analogous to the bubble concept for
consolidated facilities that EPA has put forth in recent months....
We believe that diesels are different enough from gasoline powered
cars that the standard and CAPED [ Corporate Average Particulate
Emissions from Diesels] should be limited to diesels.”
Volvo —— “In principle, Volvo supports the “bubble” concept of
emission standards exemplified by the General Motors “CAPS” pro-
posal. . . .Volvo would expect to be able to comply with the GM CAPS
scheme.”
Ford —— “ [ GM’s proposal contains] some potential sources of prob-
lems which should be carefully assessed and resolved before taking
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any action. For instance, the GM CAPS proposal could be inter-
preted to require exhaust particulate determination for all ve-
hicles, including those powered by gasoline engines; such an
interpretation would result in an unacceptable increase in certifi-
cation workload. [ It] might introduce difficulties associated with
“mix management” of a manufacturer’s total product offerings. At
any rate, if the proposals were accepted, for the sake of consis-
tency, consideration must also be given to the adoption of an
equivalent averaging scheme for the currently regulated HC, CO, and
NOx emissions.”
Department of Energy —— “Averaging of particulate emissions over a
number of vehicles (new and in—use, gasoline and diesel) as pro-
posed by one manufacturer and discussed in the hearings has a
number of economic, legal, and environmental implications which
would require greater exploration prior to any adoption of this
approach. .. . If such a proposal is considered, it would require a
new rulemaking procedure to allow all interested parties an op-
portunity to comment specifically on that proposal.”
Volkswagen — — “Volkswagen wishes to emphasize the following; a)
Introduction of a CAPS—concept would result in a restriction of the
diesel—content in the fleets sold by all manufacturers. We strong-
ly believe that such a restriction is clearly beyond EPA’s statu-
tory authority. While Congress authorized EPA to set up techno-
logically feasible standards for particulate emissions, certainly
it did not authorize EPA to limit the percentage of diesels sold by
a manufacturer; b) The CAPS concept starts from the assumption
that particulate emissions from gasoline—fueled vehicles are zero.
This assumption is known tO be incorrect. We believe that EPA
cannot issue certificates of conformity based upon such false
assumptions; c) The CAPS concept is anticompetitiVe because it
favors big manufacturers with Large gasoline—fueled fleets.
Smaller manufacturers selling the same number of diesel vehicles as
a big manufacturer would have to apply more advanced technology on
their diesel vehicles just because they [ sell] fewer gasoline-
vehicles.”
Peugeot —— “In principle, we cannot agree to this approach for the
following reason: For 1977 calendar year, our market share in the
U.S. for diesel vehicles was 52% and was 66% in 1978. We have
no reason to believe that this percentage will decrease in the next
years. In those conditions, in 1981, to meet GM CAPS of 0.2 gpm,
Peugeot diesel vehicles would have to be lower than 0.33 compared
with 0.6 gpui in the NPRN of EPA. In 1983 to meet the GM CAPS of
0.1 gpm, Peugeot would need to be lower than 0.17. If that propos-
al is adopted, Peugeot diesel vehicles will be excluded from U.S.
market, even though particulate levels of our cars will be lower
than those of GM... We feel our position is probably the same that
any manufacturer with a high sales percentage of diesel vehicles.”
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Associate Professor Edward J. Farkas, University of Waterloo ——
“ In my opinion the corporate overall standard approach is very
undesirable for several reasons: 1. It does not meet the ele-
mental criterion of fairness. It means that certain motorists will
drive dirtier cars than other motorists. If motorists see the
dirtier cars as more desirable, or if it is more expensive, it
means that what are in effect privileged motorists will be driving
the dirtier cars. 2. SureLy the enforcement of a corporate
overall standard is much more complex, both for the manufacturer
and for the EPA, than a standard that simply says that each vehicle
must emit a certain number of grams per mile or less.”
Citizens for Clean Air, Inc . —— “We concede that the fleet averag-
ing concept would alLow the manufacturers some flexibility in
marketing. However, it would also allow for the possibility of
concentrated operation of high—emitting diesel vehicles in densely
populated urban areas such as mid—town Manhattan. There would be
an immediate economic incentive for diesel taxis and jitneys if a 1
gpm standard were adopted and full—sized diesel vehicles became
readily available for this application.”
Natural Resources Defense Council —— “Under the GM proposal, its
light—duty diesel vehicles would have average particulate emissions
of 1.0 gpm by 1981, 0.5 gpm by 1985, and 0.2 gpm by 1990. This
would allow light—duty diesel vehicles to emit 66% and 150% more
particulate in model years 1981 and 1983 respectively than would be
allowed even under the EPA standard as proposed. .. Section 202 of
the Clean Air Act Amendments of 1977 states that the reguLations
are to require the greatest degree of control achievable through
the application of technology available in the model year to
which the standard would apply. A lesser degree of control such as
that proposed by GM to ensure greater flexibility to the manufac-
turers is clearly not acceptable under the Act.”
Anal y 51. S
There are two primary advantages of an emission averaging
standard as opposed to a per vehicle emission standard. The first
is the increased flexibility that a manufacturer has in determining
how it is going to comply with the emission standard. Instead of
having to design each engine family so that it can certify at or
below the emission standard, the manufacturer only has to conform
to the requirement that its sales—weighted average emission level
is equal to or less than the emission standard. The second advan-
tage of an averaging approach, a result of the added flexibility,
is that the manufacturer is able to optimize its control technology
strategies with respect to economics; as the Council on Wage and
Price Stability pointed out, it may quite likely be more cost—
effective for the manufacturer to control one engine family to a
very low emission level while controlling a second engine family
correspondingly less, than to control every engine family to the
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very same level. Two different averaging approaches were proposed
during the comment period. General Motors suggested a plan whereby
the sales—weighted average of a manufacturer’s diesel and gasoLine
fleet would have to be equal to or less than the Corporate Average
Particulate Standard (cAPS). Volkswagen suggested a similar plan
but which would incorporate only diesel vehicles; this Diesel
Average Particulate Standard (DAPS) is discussed later in this
section.
We agree with GM that an additional positive aspect of the
CAPS proposal is that it would put a “lid” on diesel particulate
emissions. Once a manufacturer reached approximate equilibrium
with the CAPS, any increase in the number of diesels sold by that
manufacturer would have to be accompanied by a corresponding
reduction in particulate emission Levels (assuming constant total
sales by the manufacturer). Thus the total diesel particulate
loading to the atmosphere would be relatively constant, except for
small increases due to increasing total sales by the industry.
As the above comments indicate, there are many concerns about
the CAPS proposal. Volkswagen and Peugeot both pointed out that
the concept allows manufacturers who produce larger quantities of
gasoline—fueled vehicles to market higher particulate—emitting
diesels than manufacturers who sell fewer gasoline—fueled vehicles.
Mercedes (who expressed opposition to CAPS at the public hearings)
and Peugeot would be the manufacturers most affected as both
manufacturers presently sell about 65 percent diesels; for these
two manufacturers GM’s proposal would be much more stringent than
the standards EPA is promulgating. GM suggested two possible
solutions to this dilemma in its comment: 1) a period of exemption
from the standards for certain manufacturers and 2) a provision
allowing these manufacturers to “obtain” additional particulate
emission tonnage from other manufacturers not using their allot-
ments. We find neither of these solutions to be promising at this
t ime.
Citizens for Clean Air commented that GM’S maximum particulate
ceiling of 1.0 gpm (0.62 g/kin) could allow the possibility of
localized particulate impact problems in certain cities, neighbor-
hoods, or roadways which might have an unusually high concentration
of high particulate diesels. One likely possibility here would be
the dieselization of the New York City taxi fleet.
Associate Professor Farkas commented that enforcement would
likely be complicated under an averaging approach. Our preliminary
analysis of this issue confirms his suspicion. The approach that
has been recommended by GM would involve enforcement on an engine
family basis. Each engine family would have a particulate enforce-
ment level which would be the product of its certification level
and the manufacturer’s safety factor, defined as the ratio of the
CAPS to the manufacturer’s projected corporate average particulate
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level. Thus, if the CAPS was 0.10 g/mi (0.062 g/km), and the
manufacturer’s projected corporate average particulate level was
0.08 g/mi (0.050 g/km), that manufacturer would have a safety
factor of 1.25, and each of its engine families would have an
enforcement Level 25 percent greater than the appropriate certifi-
cation value. Any engine family with an SEA particulate value in
excess of its particulate enforcement level would then be subject
to an order of corrective action.
The primary difficulties associated with enforcement on an
engine family basis arise due to the fact that while the fleet—wide
standard that must be met by the manufacturers would remain con-
stant throughout the model year, the enforcement levels for the
engine families would be subject to change. This is because the
enforcement levels are dependent on the manufacturer’s safety
factor, and thus on the sales distribution (which could fluctuate
throughout the model year) as well. During the certification
process, the safety factor would be calculated based on the manu-
facturer’s projected sales. Yet any final determination of the
safety factor would not be possible until the end of the model
year, when the actual production figures would be known. This
could lead to several possible problems. For example, it can be
shown that it is possible, due to a change in the manufacturer’s
production distribution, for all of a manufacturer’s engine fam-
ilies to be in compliance with their respective enforcement leveLs
(as calculated during certification) while its corporate average
particulate Level could be exceeding the CAPS. A changing produc-
tion distribution, and thus a changing safety factor and enforce-
ment level, could also portend the scenario where an engine family
would be declared to be in compliance immediately following an SEA
test, but could be in noncompliance later in the model year. These
two examples briefly illustrate the difficulties inherent in
attempting to enforce on an engine family basis when the standard
is fixed only on a fleet—wide basis.
Volkswagen and the Natural Resources Defense Council (NRDC)
both claimed that the CAPS approach could not be promulgated within
the authority given to EPA by the Clean Air Act. Volkswagen
asserted that CAPS would restrict dieselization and the NRDC felt
that CAPS would not provide the “greatest degree of emission
reduction achievable.” Finally, Volkswagen and Ford commented on
the problem of how to handle gasoline—fueled vehicles under a
concept which averages together the particulate levels of both
diesel and gasoline—fueled vehicles. All of these concerns are
being scrutinized.
EPA is seriously evaluating GM’s CAPS proposal and is anal-
yzing the various concerns delineated above. A more complete
evaluation of the concept should appear in the final Regulatory
Analysis. Regardless of the final evaluation, we agree with the
Department of Energy that should EPA decide to support an averaging
approach, a new rulemaking procedure would be necessary. EPA
certainly could not finalize what it has not officially proposed.
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C. Diesel Average Particulate Standard (DAPS )
Comments
Volkswagen —— “This VW proposal suggests a standard applicable to
the average diesel particulate emissions of each manufacturer’s
fleet of all diesel Light duty vehicles. We suggested calling this
standard the Diesel Average Particulate Standard (DAPS). It is
similar in design to the Average Fuel Economy Standard. DAPS
limits the sales weighted mean of the particuLate emissions of all
diesel vehicles sold by a manufacturer during a modeL year Land]
would allow manufacturers to mix the diesel models sold on the
market in such manner so that their diesel fleets comply with DAPS.
Compliance with DAPS is determined by calculating the Diesel
Average Particulate Emissions (DAPE) for each manufacturer from the
certification data and the Projected Sales Figures. Whenever the
DAPE for a manufacturer is smaller than or equaL to DAPS the
Administrator shall issue a certificate of conformity with DAPS.
Such certificate of conformity may provide that the sales mix may
not be altered to such an extent that the manufacturer’s DAPE
exceeds DAPS at the end of the model year. In order to make the
DAPS concept work with respect to the SEA, emission warranty, and
recall provisions of the Act, it is necessary to establish indivi-
dual controL limits in addition to DAPS. Such control limits for
individual vehicles and individual engine families could be called
Diesel Individual Particulate Standards (DIPS). They would be used
solely to determine compliance with the enforcement provisions of
the Act. . . .Reasonirtg for introduction of DAPS and DIPS: a)
Contrary to the CAPS concept, the approach suggested here is
consistent with the Clean Air Act as it can be implemented immedi-
ately upon introduction LwithoutI having to amend the Clean Air
Act; b) Contrary to CAPS concept, there is no negative impact on
competition if the DIPS/DAPS concept is compared with a traditional
standard concept; c) The DAPS/DIPS concept specifically regulates
particulate emissions from all Light—duty diesel vehicles. There-
fore, such particulate standards are still technology—forcing,
while standards under a CAPS concept are mainly sakes—mix—forcing;
d) The DAPS/DIPS concept would allow manufacturers to make use of
diesel technology as a contribution to the effort of the U.S. to
conserve energy. Because large diesel cars with relatively high
particulate emissions could be offset by small diesel cars, the use
of diesel technology is not restricted to small diesel cars.
Under a diesel—bubble concept, DAPS of not lower than 0.6 g/mi for
model years 1981 and 1982, 0.4 g/mi for model years 1983 and 1984,
and 0.3 g/tni. for model year 1985 and subsequent model years could
be established.”
Council on Wage and Price Stability — — “One specific program that
merits consideration is the following: whatever the standard EPA
chooses would be established as a Corporate Average Particulate
Emissions from Diesels (CAPED) standard. We believe that diesels
are different enough from gasoline powered cars that the standard
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and CAPED should be limited to diesels. At the completion of the
certification testing of the 50,000 mile durability fleet, each
manufacturer (or EPA) would establish a limited number (say, five
to ten) of categories of diesel cars for the purpose of particulate
emissions control and would establish a separate particulate
standard for each category. Each model assigned to a given cate-
gory would not be aLlowed to exceed the standard established for
that category. The 4000 mile emissions data fleet could be cer-
tified in this fashion. EPA’s Selective Enforcement Auditing of
assembly line vehicles would use these category standards, as would
any warranty or recall action. At the end of the model year,
compliance would be judged by whether the manufacturers’ CAPED—--the
sales—weighted average of emissions (sales in each category mul-
tiplied by that category’s emissions standard, divided by total
corporate diesel automobile sales)—--was at or below the overall
standard. If the CAPED exceeded the standard, the manufacturer
would be declared to be out of compliance forthat model year, and
the penalties of Section 205 of the Clean Air Act could be in-
voked.”
Peugeot —— “As a principle we favour the DAPS concept since it
allows a manufacturer a better flexibility as he may find the best
compromise between several requirements: emissions, particulates,
fuel economy, without any overall change of the total emission
impact of the particulates upon air quality. However, before
giving our final comment we wish to know the detail of this pro-
posal.”
Volvo — — “ [ Wie do not consider the DAPS and DIPS approach, sug-
gested by Volkswagen, to be acceptable for a manufacturer such as
Volvo.”
Anal y s is
As mentioned above, the primary difference between GM’S CAPS
proposal and VW’s flAPS/DIPS proposal is that the latter averages
the particulate emissions from diesel vehicles only while the
former averages particulate values from diesel and gasoline—fueled
vehicles. Otherwise the two proposals share the same philosophical
underpinnings, and thus the DAPS/DIPS proposal shares many of the
same advantages and disadvantages of the CAPS approach discussed
above. It would give the manufacturers more flexibility in com-
plying with the particulate standards, and would permit them to
comply in a more cost—effective manner. Alternatively, there are
the same concerns about possible localized impact and enforcement
problems of the DAPS/DIPS proposal, and the same question of
whether such an averaging approach is permissible under the Clean
Air Act mandate of the “greatest degree of emission reduction
achievable.”
We agree with VW that one advantage of their proposal, WhLCh
only averages diesel particulate levels, is that it is more eqULt
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able to those manufacturers who produce significant percentages of
diesels. Regardless of how many gasoline or diesel vehicles a
manufacturer sells, each manufacturer would have to compLy with the
same diesel average particulate level. This very characteristic
also means that the DA.PS/DIPS approach does not put a “lid” on
diesel particulate emissions, however, as the CAPS proposal does.
The Council on Wage and Price Stability (CWPS) agrees with VW
that an averaging approach should involve diesel vehicles only, but
their proposal involves a slightly different enforcement mechanism.
While VW proposed an enforcement program very similar to the one
suggested by GM, CWPS suggests that the manufacturer or EPA set a
limited number of particulate “categories” (apparently not neces-
sarily synonymous with engine familes), each with a separate, fixed
particulate standard. These categories would be sales—weighted and
averaged at the end of the model year to determine fleet—wide
compliance. CWPS suggests that these category standards could be
used for SEA as well. The advantage of this approach is that the
SEA enforcement levels are fixed, and are not dependent upon the
manufacturer’s sales distribution or safety margin. It is still
possible for a manufacturer to be complying with all of its cate-
gory standards, however, while being in noncompliance with the
fleet—wide average, due to greater than projected production of
certain model lines. Still, the CWPS suggestion does eliminate one
of the uncertainties involved in the engine family enforcement
approach (the likelihood of a changing safety factor) and thus is a
contribution to the analysis of the various averaging approaches.
D. Recommendation
EPA should continue to evaluate the various averaging ap-
proaches proposed during the comment period, and should include a
complete evaluation of them in the final Regulatory Analysis. It
must be emphasized again that should EPA decide to propose such an
approach, a new rulemaking package would be required to give
interested parties the chance to comuient on any specific proposal.
EPA does not consider smoke standards to be a legitimate alter-
native approach to diesel particulate standards.
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VII. Test Procedure
This section contains the summary and analysis of comments
that deal with the proposed test procedure. While General Motors’
comments were quite comprehensive, overall relatively few comments
were received under ths general subject area. Comments on the
major test procedure related items, such as the sample zone temper-
ature specification, hydrocarbon sample temperature specification,
filter acceptance criteria, etc., are presented first in the
standard format of this document. The more minor items, plus
editorial and correcton comments are presented in an abbreviated
form at the end of this section (Part M).
A. General Comments
Comments:
General Motors —— “Because of the timetables for test equipment
acquisition, we recommend that EPA immediately initiate dialog to
finalize the technical details of the proposed measurement system.”
Analysis
Dialog concerning the light—duty diesel measurement system was
initiated when the Draft Recommended Practice was issued in March,
1978, and continued through the close of the comment period for the
proposed regulations. The industry was invited to submit comments
on the recommended practice. Comments received were analyzed, and
a revised test procedure was issued in October, 1978 in order to
provide maximum leadtime in this area. In addition, in January
1979, EPA technical staff requested* General Motors to submit
relevant data on several topics related to the diesel test proce-
dure. The light—duty diesel rulemaking process, especially the
public hearings (March, 1979) continued the dialog on the measure-
ment system. However, only relatively few comments concerning the
measurement system were submitted through these latter mechanisms,
even though the industry had from October, 1978 through April 19,
1979, (when the comment period officially closed) to prepare
comments on the measurement system. A letter outlining the changes
expected to be made to the test procedure in the final regulation
was mailed to the industry on July 25, 1979. EPA technical staff
concluded that an adequate dialog has been maintained.
Recommertdat ion
None required.
Comments
B. Hydrocarbon DoubleCOUfltifl&
* Letter from Charles L. Gray, Director, ECTD to Thomas Fisher,
Director, Automotive Emission Control, GM Technical Center, dated
January 9, 1979.
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General Motors arid International Harvester —— have commented that
the temperature specifications cause some hydrocarbons to be
counted both as a particle and as a gas.
Analysis
General Motors ’ comment emphasized that the temperature
specifications are the problem. However, the real issue centers
around EPA’s intent to measure both total hydrocarbons and total
suspended particulates. The temperature specifications are natur-
ally the result of this intent, and not the problem.
The intent to measure both total hydrocarbon and total sus-
pended particulate material results from the fact that each is
regulated for a different reason. Hydrocarbon emissions standards
are intended to reduce the atmospheric photo—oxidant smog Level;
standards for total suspended particulates are intended to reduce
the respiratory health hazard associated with these fine materials.
Therefore, the proposed measurement practice as specified in
§86.110—81(b) should be continued until it can be conclusively
proven that particle—bound hydrocarbons do riot leave the particle
while suspended in the atmosphere, and hence do riot first consti’-
tute a respiratory health hazard arid later contribute to the
atmospheric photo—oxidant level.
General Motors submitted thermogravametric (TGA) data to EPA
as evidence that the particle—bound hydrocarbons do not leave the
particle and become free in the atmosphere. While interesting,
this data falls short of being conclusive because TGA does not
closely simulate real atmospheric conditions, and therefore does
not answer the question of what really happens in the atmosphere.
It must be emphasized that since the standards have been based
on a baseline allowing some double—counting) and because the
standards are technology—based, the double—counting does not affect
the stringency of the standards. Halting the double—counting would
necessitate a new baseline, a new technological review, and a lower
set of standards.
Recommendation
No change to the temperature specifications should be made at
this time.
C. Sample Zone Temperature Specification
Comments
General Motors, Daimler—Benz, Ford and Chrysler —— have Commented
that the 125SF particulate sample zone temperature limit is arbi-
trary and without technical foundation.
Analysis
-------
From the outset of diesel particulate measurements and pub-
lished practices, a 125°F limit on the sample zone temperature has
been used and specified ( 86.llO—81(b)(1)—(2) and (6)). Both
industry and EPA agreed that some limit was necessary in order to
prevent a loss of hydrocarbons by thermal desorption. The limit
was set at 125° to be sure that little hydrocarbon would be ther-
mally desorped. Further, this limit was considered a maximum that
would realistically occur in the atmosphere. It also permits
reasonable dilution ratios in the sample system.
Data now available indicates that the 125°F limit on the
sample zone temperature was a reasonable choice.
Data generated at the Ann Arbor EPA lab indicates that partic-
ulate losses begin to occur at temperatures slightly below 125°F
(see Figure vu—I). Further, Ricardo Consulting Engineers devel-
oped data (under EPA Contract No. 68—02—2751) which indicates that
the hydrocarbon content of the particles decreased at filter
temperatures exceeding 140°F. With an allowance for initial
desorption temperature, the 125°F limit is considered very reason-
able.
General Motors submitted temperature effects data from which
they concluded that the 125°F limit is not necessary. EPA has
reviewed this data, and does not agree with the GM conclusion.
Their submittal presented six sets of data (including repeat
testing) in which particulate emissions from an Oldsmobile were
graphed as a function of the maximum sample zone temperature (see
Figure VLI—2). In four out of the six sets, the particulate
emissions decreased with increasing temperature (maximum sample
zone temperature ranged from 106° to 160° F). Similar data was
presented for an Opel, and again, four out of the six sets indi-
cated lower particulate emissions with increasing sample zone
temperature (maximum sample zone temperature ranged from 95° to
135° F). This data therefore, does not substantiate a change in
the sample zone temperature.
It should be noted that the 125°F sample zone limit will
require CVS units with pump capacities higher than those in current
use, especially for the larger engines (greater than a 3L). This
means that gaseous exhaust samples with lower concentrations will
be collected in the bags. However, the concentrations experienced
will still be within the sensitive range of present day analyzers.
Testing of various engine sizes with a single CVS size currently
requires that analyzer ranges be selected according to concentra-
tion. Therefore, lower concentrations are not expected to be a
major problem.
Recommendation
The maximum sample zone temperature limit should not be
raised.
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FIGURE VII — I
PARTICULATE AS A FUNCTION OF TEMPERATURE
EPA MEASUERNENTS
MERCEDES-BENZ 300D MERCEDES-BENZ 300D PEUGEOT O4
ROT tA4 FTP .5 ROT LA4
q x I i-i •0 I
_ I I_ + 0
I A ‘ 1•
1Z5R .
.3 .3. gzz”F .3 —
.2 . .2 2
.1 .1• .1
I p ‘ , I I • • I I j p I I I i I I • I I I I I I I I I I I I I I I I t I I I I I - .J
Zo ‘go ( o o /00 Zo “10 95 io ‘lo o 6’o /00 Izo ,qo 95 zo 4o , , ic’o lZo /1/0
PEAK SANPLE ZONE TEMPERATURE IN DECREES FAHRENHEIT
SYMBOL LEGEND
DYNO”A” SINGLE DILUTION X... DYNO “A” DUAL DILUTION
t — DYNO”B” SINGLE DILUTION 0 — DYNO “B” DUAL DILUTION
DYNO “C” SINGLE DILUTION
-------
FIGURE VII — 2
PARTICULATE AS A FUi lCTION OF TEMPERATURE — SUMMARY OF G.M. MEASUREMENTS
T ST PHASE I I8” TUNNEL TEST PHASE I— 8” TUNNEL
•75 JDO 125 ISo I’IS 5 ,
PEAK SAMPLE ZONE TEMPERATURE IN DEGREES F.
TEST PHASE 11-18” TUNNEL TEST PHASE II- 8” TUNNEL
.8
4
V
.
L4 ,.
V i ioo ,
p
‘is
/00
150
175
—
ISO
i75
PEAK
SAMPLE
ZONE
TEMPERATURE
IN DEGREES F.
SYNBOL LEGEND
A OLDSMOBILE DIESEL
OLr MOBILE
DIESEL
RETEST
OPEL DIESEL
0
OPEL DIESEL
RETEST
.1
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D. FiLter media
Comment
Ford —— has commented that fluorocarbon—coated glass fiber filters
should not be required.
An a Ly s is
This comment can best be addressed by stating the EPA position
on the filter media. The fluorocarbon—coated gLass fiber medium
has been recommended (S86.1lO—8l(c)(4)) as optimum for collection
of diesel particles for three prime reasons: (1) there is less
interaction with high moLecular weight gaseous orgariics than the
uncoated glass fiber options, (2) less hygroscopic and more
mechanically sound than the uncoated glass fiber options, and
(3) lower pressure drops than the teflon membrane options. This
position remains unchanged.
Ford further commented that this type of filter is known to
cause chemical degradation of some samples. It is acknowledged
that this may happen, but it is not considered to be important in
the present certification application, because appreciable total
particulate mass changes do not result. Chemical composition
changes could be important to the assessment of health effects,
however.
Nevertheless, if a manufacturer desires to use an alternate
fluorocarbon—based filter media, this should be allowed as long as
the filter meets the acceptance criteria specified in the final
regulation.
Recommendat ion
Revise S86.11O—81(c)(4) to include fluorocarbon—based filters,
as well as the fluorocarbon—coated glass fiber filters already
required.
E. Filter Efficiency
Comment
General Motors, Volkswagen and Fiat —— have commented that the
procedure for assessing the collection efficiency of the filter is
not acceptable.
Analysis
The filter efficiency test specified in the NPRM (S86.11081
(c)(l)(i)—(v)) is intended to establish a filter and sample system
acceptance criteria with respect to diesel particulate material.
To do so requires the involvement of the driving cycle, the vehi—
136
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cle, filter lo irig, sample system, etc. As noted by Kittelson,
Dolan and Kadue,, in CAPA1378 Progress Reports 8 and 9 (dated June
6, 1979) on Laboratory and Field Studies of Aerosols Produced by
Diesel—Powered Vehicles “...there is some disagreement between the
laboratory (D0P) and field characterization of these (T60A20)
filters.” [ Parenthesis added]
Data presented by General Motors indicates that filter effi-
ciency increases with loading (see Paliflex T60A20 unheated and
Paliflex TX4OHI2OWW data in Table vu—i). This is consistent with
the results of the other researchers in this regard. Data gener-
ated at EPA indicates that filter efficiency will have to be
optimized as a function of the vehicle, i.e., filter efficiency
results seem to be somewhat vehicle dependent (see Table VuI—2). A
standard procedure such as the General Motors recommended DOP (ASTM
D—2986) does not consider these variables, and therefore does not
provide a satisfactory acceptance criteria for diesel particulate
filters. Further it provides no check on the sample system.
General Motors indicated that the efficiency test does not
perform as intended, apparently because initial tests (at GM)
failed to find a passing filter. However, data presented by
General Motors (Table vu—i) indicates that they ultimately
achieved 98 percent efficiency (EPA calculation) by optimizing
their sample flow rate and loading. This is exactly the result
that the efficiency test is intended to achieve.
Fiat commented that a more correct approach to the definition
of filter efficiency requires that the back—up filter be a quasi—
absolute filter such as electrostatic precipitator. This may be a
good recommendation from an ideal procedure point of view, but
would be difficult to put in place for day—to—day testing.
Comment
Ford, Volkswagen and Fiat —— have commented that the 98 percent
filter efficiency (EPA procedure) requirement is too high.
Analysis
Data now available indicates that universal compliance with
the 98 percent filter efficiency requirement (86.11081(c)(1)) will
be difficult to achieve with fluorocarbon—coated glass fiber
filters (see Table VII—2). Ford commented that a collection
efficiency greater than 95 percent should not be required.
This comment is consistent with the analysis and conclusion
stated in the EPA Technical Report “Particulate Measurement —
Efficiency of Pailfiex T60A20 Filter Media” (SDSB—79-22 dated July
1979), except for one slight modification: the report concluded
that for those vehicles in which 95 percent filter efficiency
cannot be achieved the combined weight of the first filter and the
back—up filter.must be used in calculating particulate emissions.
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Table Vu—I.
Filter Efficiency Test Data
GM Results
— Filter
F Luorocarbon
coated glass
fiber filters
Flow Rate
(cfh)
1st Filter
mg
2nd Filter
mg (Eff)*
3rd Filter
rug (Eff)**
Gelman A/E
20 1.829
0.087 (95.2)
‘ w 2
*EfficIency (1 ) 100%
— Wl +
**Efficiency = (1 —
+ w 3
) 100%
+ AW 2 + W 3
NOTE: While GM did not indicate filter size, 10 cfh and 0.815—0.897
rug are below the specified flow rates and filter loading for even
the minimum specified filter size. It cannot be expected that the
filter would perform as required.
Pallflex T60A20
10
0.815
0.050
(94.2)
0.035
(89.6)
30
2.167
0.062
(97.2)
0.043
(95.2)
50
3.101
0.051
(98.4)
0.044
(96.9)
Pailfiex TX4OHI2OWW
10
0.897
0.039
(95.8)
0.026
(92.8)
(>99% efficiency
30
2.087
0.042
(98.0)
0.031
(96.5)
claimed on the DOP
50
2.782
0.046
(98.4)
0.029
(97.3)
test)
Pallfiex T60A20
20
0.838
0.004
(100.5)
(filters located in—
30
1.635
—0.011
(100.7)
side heated (375°F)
50
2.465
0.009
(99.6)
oven for test)
60
3.380
0.039
(98.9)
Glass fiber filters
138
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Table VF 2
Paliflex T60A20 Filter Efficiency Test Data
EPA Results
Peugeot 504D
Filter Efficiency* — Percent
Filter Batch Bag 1 Bag 2
3991E2 92.0 91.7
1092B 91.4 93.7
4009E2 90.7 93.5
Oldsmobile 350D
Filter Efficiency* — Percent
Filter Batch Bag 1 Bag 2
3991E2 98.0 98.4
1092B 99.1 99.1
4009E2 99.0 99.2
*Filter efficiency determined per Section 86.11O—81(c)(1)(iV).
139
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It should be noted that Fiat’s filter efficiency comment is
based on measurements in which a glass fiber back—up filter was
used. Such efficiency measurements will be erroneously low because
of hydrocarbon adsorption by the glass fiber media. The back—up
filter will indicate a particulate net weight increase that is too
high because of this HC adsorption.
Recommend at ions
Ott the basis of the above analyses, it is recommended that
S86.11O—81(c)(1) be revised as follows:
1. Rename the efficiency test and call it “Filter Acceptance
Criteria.”
2. Require the back—up filter during actual certification
testing.
3. Calculate the ratio of weights as indicated in the NPRN.
4. If the ratio is greater than 0.95, determine paticulate
emissions on basis of first filter net weight.
5. If the ratio is less than 0.95, determine particulate
emissions on basis of combined net weights of the first filter and
the back—up filter.
F. Filter Flow Rate and Loading
Comment
General Motors —— has recommended that the required flow rate
provision be dropped and that a reasonable filter weight gain be
kept. However, the recommended weight gain window is tighter than
needed for good measurement accuracy.
Anal ys is
It is agreed that the specified filter flow rates can be
dropped. The requirement for constant sample flow rate during the
test is a sufficient flow requirement to assure good measurements.
However, the specified 2 tng minimum loading (on a 47 filter) is
necessary to achieve high efficiency. GM’s own data indicates this
(see Table Vu —i). Higher loadings can be left to the manufac—
turer’s own discretion.
Recommendation
It is recommended that the specified filter flow rates be
dropped, and that only the minimum 2 mg filter loading be required.
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G. Post—Test Filter Stabilization Period
Coimne nt
General Motors —— has requested that the regulations be changed to
require a one—hour minimum filter stabilization period after a
vehicle test. GM further commented that there is no need for the
5 6 —hour maximum time limit on the filter stabilization period.
Analys is
EPA has no objection to shortening the minimum post—test
stabilization period specified in §86.139—81(e). General Motors
indicates that using a one—hour post—test stabilization period
instead of a 24—hour stabilization results in an 0.5 percent
increase in measured particulates. General Motors is requesting
the one—hour lower limit in order to minimize any interference with
mileage accumulation. They feel that the penalty of accepting the
higher particulate measurement is outweighed by the advantage of
speeding up the certification process. However, for best accuracy,
it is recommended that EPA use a minimum 24—hour stabilization
period (used in baseline testing) for certification testing. Some
correlation problems may result with manufacturers that use a very
short period, but this is at the manufacturer’s own risk and at
their option.
It should be noted that the 56—hour specification is the upper
limit of a range that currently varies from 8 to 56 hours. The
upper limit was specified to cover weekend operations at various
test facilities. This is reasonable because, as GM stated, addi-
tional time (assumed beyond 8 hours) has no effect on filter
stabilization.
Recommend at ion
It is recommended that §86.139—81 be revised to allow a
one—hour minimum post—test filter stabilization period. The upper
limit of 56 hours should remain as proposed.
H. Heat Exchanger Requirements
Comments
General Motors —— has commented that the specific requirement for a
heat exchanger (with the CFV sampler) should be replaced by a
general requirement for flow proportionality.
An aly s is
Conceptually, this statement is correct because the function
of the heat exchanger in the CFV/diesel particulate application is
to provide for proportional sample flow by compensating for varying
gas temperature in the dilution tunnel. However, a change to the
141
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test procedure cannot be recommended because no confirmatory data,
specifications or schematic diagrams of the proposed alternate
sample system were provided with the comment. As stated in §86.110
—81(a)(5) , other sampling systems may be used if shown to yield
equivalent results and are approved in advance by the Adminis-
trator. Confirmatory data and system diagrams are among the
necessary items needed to receive approval.
Confirmatory data is necessary in order to show equivalency
between the alternative measurement system being proposed and
either of the specified systems (S86.110—81(b)(1)—(2)). Stated
another way, evidence that the alternative is practical and works
must be submitted to EPA. Diagrams and specifications are required
for inclusion in the Federal Register so that any testing labor-
atory can duplicate the system.
For the record, it should be noted that General Motors has
proposed to compensate for temperature by using a critical flow
sample probe. They further propose to put the filter ahead of the
nozzle to prevent contamination. However, placing the filter in
this position introduces another problem; particulate material
collected on the filter alters the upstream sample nozzle pressure
which in turn results in non—proportional flow. General Motors
would eliminate this problem by using a back pressure regulator or
servo—controlled valve that keeps the sample venturi inlet pressure
proportional to the CFV inlet pressure, and thereby maintain
proportional sample flow. They further recommended a tolerance on
the proportionality of + 2 percent at all times during testing.
While this is certainly an interesting sampling technique that
may have potential, it cannot be accepted without knowing the
practical working details.
Recommendation
It is recommended that the General Motors proposal not be
adopted at this time.
I. Tailpipe Connector Specification
Comment
General Motors —— has commented that the tailpipe connector speci-
fication is too rigid.
Analysis
The current tailpipe connector specification ( 86.1108l
(b)(3)) of a maximum length of twelve feet of smooth (non—flexible)
pipe is considered by General Motors to be a serious handicap to
facility design. General Motors has submitted data which indicates
that particulate measurements made using 17 feet of four—inch
142
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iexible pipe are equivalent to measurements made using 7 feet of
two and one—half—inch smooth pipe over a hot start LA—4 cycle. EPA
data (memo from Thomas Penninga to F. Peter Hutchins entitled
“Diesel Particulate Exhaust Collection Configuration Study — A
Preliminary Look at the Data,” dated March 29, 1979) indicates that
this equivalency may be due to several competing effects taking
place in the GM pipe comparison. This EPA data from a Mercedes
300D and from an Oldsmobile 350D indicates that particulate mea-
surements increase with pipe diameter (7% to 127. in going from two
and one—half inch to four—inch diameter), and decrease with con-
nector length (—2% to —4.5% in going from 12 feet to 20 feet) and
roughness (—4% to —13% in going from smooth to convolute pipe).
The EPA data further indicated that insulating the pipe
could result in an increase in particulate measurements of up to 16
percent (smooth pipe). Increased heat loss could also be a factor
in the particulate measurements taken with 17 foot (GM) and 20 foot
(EPA) lengths of pipe. The specific particulate loss mechanism
related to this heat loss may be thermal precipitation.
From the above discussion it is apparent that a more thorough
understanding of the tailpipe connector effects on particulate
measurements is needed. EPA is therefore planning to conduct more
testing in the area of tailpipe heat loss effects. Specifically,
particulates will be measured using a 20 foot length of smooth
insulated pipe. These measurements will be compared to measure-
ments taken with a simiLar 12 foot i,nsulated pipe, and also mea-
surements taken with a 12 foot uninsulated pipe (the baseline
reference pipe). EPA will allow the longer alternative if the data
indicates that this is reasonable.
Efforts will be made to place the most practical solution into
the final rule. If this cannot be done, then a technical amendment
will have to be issued.
Recommend at ion
It is recommended that no change be made to the tailpipe
specification until EPA testing has been completed.
J. Flow Measurement
Comment
General Motors —— has commented that gas meters are a burden.
Equivalent flow measurement devices which can be operated automa-
tically should be allowed.
An a lys is
It is agreed that gas meters are a burden. It was never
intended that the test procedure would eliminate automatically-
operated flow instrumentation.
143
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Recommendat ion
It is therefore recommended that a more general term such as
“flow instrumentation” be used in addition to the words “gas
meter.”
Comment
General Motors —— has commented that the +5 percent tolerance
on sample flow rate is too large. They suggest a tolerance of +2
percent. —
Analysis
It is agreed that a tolerance of +2 percent is more desirable
as it will reduce the sample error. However, it is not certain
that every laboratory can comply with this tolerance because of the
possible extra cost. No other manufacturer commented that a
tighter tolerance be adopted. Therefore, this suggestion of a +2
percent tolerance should not be adopted unless it can be proposed
and commented on by all of the manufacturers.
Recommendation
It is recommended that the +5 percent tolerance or flow rate
be retained.
K. Heated Lines (HC sample system )
Comment
General Motors —— “Commercially—available heated lines cannot
meet the proposed temperature specifications.”
Analysis
Apparently, General Motors has not realized the distinction
between probe wall temperature specifications and dilute exhaust
gas temperature specifications. It should be specifically noted
that the temperature specifications in §86—llO—81(b)(ll) and (12)
apply to the probe wall , while the temperature specification in
§86—1lO—8l(b)(13) applies to the dilute exhaust
General Motors’ comment seems to be based on dilute exhaust
gas temperature profiles measured (by GM) over the entire length of
heated line. These measurements are not necessary. The exhaust
as need only be measured before the heated filter ( 86—llO(b)(l3)
i and before the HFID ( 86.11O(b)(l3)(ii)). General Motors’ own
data (Figure vII—3) indicates that the exhaust gas temperature
specifications can easily be met at these two locations by using at
least two feet of heated line.
144
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77OiV ,d9Z AX 7 i 2’ I/’
-------
To satisfy the wall temperature specification, it is necessary
to insulate and heat the probe wall to 375°F over its entire
length. Compliance with this specification can be determined by a
single temperature sensor. The sensor must be insulated from any
heating elements and should be located on the section of probe wall
outside of the dilution tunnel.
Recommendat ion
On the basis of this comment and the analysis provided it is
recommended that:
1) The probe wall temperature sensor requirement should be
explicitly specified.
2) The words tIwall.tt and “exhaust gas” should be emphasized by
using italics.
L. SEA Related Comments
Comments
American Motors Corporation —— has recommended that a discussion of
evidence indicating that there is no compelling reason to continue
to have separate test procedures for SEA be included in the pre-
amble.
American Motors Corporation —— has suggested tabulating the speci-
fic changes that will occur in the test procedures because of the
NPRM, giving specific reasons for each change.
General Motors —— recommends that §86.608 be amended to recognize
test procedure differences between prototype certification vehicles
and production SEA vehicles.
An a ly s is
These comments indicate that clarification of the SEA test
procedure amendment is necessary.
The test procedure amendment is not intended to change the
current SEA test procedure. Current procedure will in fact con-
tinue to apply. The amendment is intended to provide for better
coordination between SEA and certification test procedures. This
will be accomplished by referencing the certification test proce-
dure for SEA testing (as in the NPRM), and including a list of
deviations (such as those pertaining to mileage accumulation test
fuel, diurnal heat build, fuel tank drain procedure, etc.). it
should be noted that the NPRM did not include this list.
146
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Recommendation
tt is recommended that a list of test procedure deviations
that apply to SEA testing be included in the final regulation. A
discussion of the intent of the SEA amendments should be included
in the preamble.
Comment
American Motors Corporation and General Motors —— have requested
that it be made clear that only exhaust emissions will be measured
for SEA.
Analysis
It is agreed that there is no intent to measure evaporative
emissions as part of the SEA program. Hence, the sections from
Subpart B which describe evaporative emission measurement equipment
and procedures (except the diurnal heat build) are not applicable
to SEA testing.
Recommendation
It is recommended that a statement be added to Subpart G
indicating that evaporative emission tests are excluded from SEA
testing.
Comme nt
American Motors Corporation —— has recommended Subparts A, B, and G
be republished in their entirety at the time of final rulemaking.
Analysis
MVEL staff in Ann Arbor are responsible for Subparts A and B.
Current time and resources prevent complete republication of these
two subparts.
SEA staff in Washington D.C. are responsible for Subpart G.
They have indicated that this subpart will be republished when
other soon—to—be—proposed amendments are finalized.
Recommendation
None required.
Comment
American Motors Corporation —— has recommended that the added cost
of measuring particulate emissions during SEA be considered. ANC
claims that it was not clear from the NPRM that only diesel vehi-
cles will be tested for particulate.
147
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Analysis
The added cost of measuring diesel particulate emissions
during SEA testing was considered in the cost analysis. No cost
analysis of particulate testing of gasoline—fueled vehicles was
made because particulate emissions from gasoline—fueled vehicles
are not intended to be measured. (Section 86.127—81(a)(2) clearly
indicates that particulate emissions are measured from diesel
vehicles only.)
Recommend at ion
None required.
Comment
General Motors — — has recommended that a more general term such as
“flow measurement instrumentation” be used instead of “gas meter”.
Analysis
This comment was covered in Part J of this section of the
Summary and Analysis of Comments. It was recommended that the more
general terminology be used, as well as the specific “gas meter”
terminology.
Recommendation
None required.
Comment
Volkswagen of America —— “It is, from our point of view, completely
impossible to set an SEA standard at the certification level
because 50 percent of the cars must fail if you are perfect.”
Analysis
This would be true if in fact the certification vehicle is a
“mean emission” vehicle and emission levels are distributed nor-
mally. If the distribution of particulate emissions follows a
pattern similar to that for gaseous emissions, that is a distribu-
tion skewed toward the high end, then the failure rate would be
less than 50 percent. In the case of gaseous emissions, experience
indicates that about 40 percent of the vehicles exceed the mean
value.
Recommendat ion
None required.
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M. Miscellaneous Comments
Comment
General Motors —— “The use of the term CVS applied to the CFV is
objectionable because it leads some to believe that it is indeed a
constant volume sampler without the addition of the heat exchanger.”
Recommendation
Replace the phrase “Critical Flow Venturi—Constant Volume
Sampler” with “Critical Flow Venturi Sampler.”
Comments
General Motors —— has recommended rewording the second sentence of
§86. 109—81(b)(2) to: “The gas mixture temperature variation
during the entire test shall be within +10°F of the average temper-
ature for the test.”
General Motors —— has recommended rewording the second sentence of
§86.]10—81(b)(2)(iii) to: “The gas mixture temperature variation
during the entire test shall be within 20°F of the average temper-
ature for the test.”
Analysis and Recommendation
While both the current and the GM wording specify the same
limit on the gas mixture temperature relative to a reference
temperature, the average temperature for the test is unknown
until after the test is finished, and therefore the heat exchanger
set point to unknown. Hence, no change to the wording of the cited
sentence is recommended.
Comment
General Motors —— “The requirement for the temperature measuring
system to have an accuracy and precision of +1.8°F (1°C) excludes
the use of “J”—type thermocouples. By changing this requirement to
+2°F (1.1°C), precision “J”—type thermocouples would be accept-
able.”
Recommendation
It is recommended that a +2°F (1.1°c) accuracy and precision
on the temperature measuring system be specified. The specifica-
tion of 1.8°F was due to inadvertant round—off in converting metric
units to engineering units.
Comment
General Motors —— has recommended rewording §86.109—81(c)(2)
149
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to add the underlined words: “. . .(as measured by hot silicone oil
or equivalent). ”
Recommendat ion
No change to the cited wording is recommended because equiv-
alent measurement techniques are handled under §86.109—81(a)(4) .
Comment
General Motors —— has recommended that separate filters and filter
holders for each test phase be used, so that filter changes during
the soak period are not required. (See Figures B81—3 and B81—4.)
Analysis and Recommendation
It was intended that separate filters and filter holders for
each test phase be allowed, as well as the two filter/filter—holder
combination diagrammed. Therefore, it is recommended that a note
indicating this intent be placed on Figures B81—3 and B81—4.
Comment
General Motors —— “The cyclonic separators shown in these figures
(B8l—2 and B81—4) for the CFV system should be deleted. The
inclusion of these separators are not required for valid emissions
tests.” (Parenthesis added.)
Analysis and Recommendation
It is agreed that the cyctonic separator is not required in
Figure B81—4. However, it is required in Figure B812 because
catalyst vehicles are tested with this system. It is recommended
that: 1) Figure B81—2 remain as diagrammed, and 2) the cyclonic
separator in Figure B8l—4 be indicated as optional.
Comment
General Motors —— “The development of turbulent flow is not enough
to ensure that particulate stratification does not occur. Upon
initial setup of the tunnel, uniform mixing should be demonstrated
through an experiment designed by the user.”
Analysis and Recommendation
It is agreed that good engineering practice requires that the
user demonstrate to himself that uniform mixing •js taking place.
It is recommended that a note suggesting this be included.
150
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Comment
General Motors —— “This requirement, that the probe face upstream,
is related to isokinetic sampling and, as such, is unnecessary. A
downstream facing probe also eliminates any chance of the test
being incorrect due to sampling particle of particulate trap
material or a large chunk of material dislodged from the tunnel
wall.”
Recommendation
It is recommended that the upstream facing probe be retained
for the following reasons:
1) This requirement is consistent with keeping the probe
inlet free from the influence of wakes or eddies produced by the
hydrocarbon probe (or any other obstruction).
2) EPA data (Technical Report LDTP 78—14 “Particulate
Measurement — Dilution Tunnel Stabilization” dated November, 1978)
infers there is very little buildup of particulate material on a
tunnel wall, and hence dislodged particulate material should be a
negligible problem.
3) Particulate trap material, if retained by the filter,
fits the current definition of particulate material, and hence
should be measured.
Comment
General Motors —— “The centerline location of the probe should be
approximate, to allow for individual probes for the various test
phases.”
Recommendation
It is agreed that the centerline probe location can be approx-
imate because of the requirement for well—mixed flow. It is
recommended that probe location be specified as “approximately on
the tunnel centerline.”
Comment
General Motors —— has recommended rewording §86.11281(a)(2) for
clarity as follows: “. . .tnaintained to within 10% relative humidity
of a set point such that deviations from a 50% relative humidity
set point could range from 40% to 60% relative humidity.”
Recomuiendat ion
It is recommended that no change to the wording of the cited
151
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sentence be made. The GM statement is Less clear than the current
statement, and it is apparently more restrictive than necessary.
Comment
General Motors — — “It is recommended that reference filters be
weighed only once each day of testing. The meaning of a condition-
ing period is not obvious.”
Recommendation
It is agreed that with the fluorocarbon based or fluorocarbon
coated glass fiber filters a reference filter weighing of once each
24—hours is sufficient as long as the humidity is maintained within
specification. Therefore, it is recommended that only 24—hour
weighing of the reference filters be required, and that a contin-
uous recording of weighing room humidity be maintained.
Comment
General Motors —— “The meaning of “micrometer” in this context is
not clear.” GM is referring to §86.112—81(b).
Recommend at ion
Delete the word “micrometer” because it currently appears in
parenthesis along side the word “readability” (i.e., the word
“micrometer” was intended to clarify).
Comment
General Motors —— has recommended that §86.120—81(f)(1) be replaced
with: “Determine the new calibration flow constant for the flow
measurement instrumentation.”
Recommendation
It is recommended that no change to §86.120—81(f)(1) be made
since: (1) some laboratories will be using gas meters, and (2)
§86.120—8l(f)(2) already provides for a calibration curve to be
used if no adjustments are made to the flow instrument.
Comment
General Motors —— “The FID optimization method presented is out-
dated. The practices recommended in SAE paper 770141, “Optimiza-
tion of a Flame Ionization Detector for Determination of Hydro-
carbon in Diluted Automotive Exhausts,” by Glenn D. Reschke should
be substituted.”
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Analysis and Recommendation
It is recommended that no change be made to the FID optimiza-
tion method presented in §86.121—81 of the NPRM. This recommenda-
tion is based upon the following analysis.
The recommendations presented in SAE paper 770141 were spec—
Lfically aimed at Beckman Model 400 FIDs. There is no assurance
that these recommendations are applicable to the several other
available FIDs. Hence these recommendations may not be universal
enough for publication in §86.121—81 which is intended to apply to
all FIDs. Consistent with this intent, no part of the general
procedures outlined in §86.121—81 prevent a Beckman user from
following the specific recommendations of SAE 770141.
Comment
General Motors —— has recommended that the underlined words be
added to the Last sentence of §86.127—81(b): “. . .using a constant
volume (variable dilution) sampler or a critical flow venturi. ”
Recommendat ion
It is agreed that the above statement is more technically
correct, and should be adopted. It is therefore recommended that
this revision be made.
Comment
General Motors —— has commented that with respect to §86.137
81(b)(5)(i): “It is not clear what gaseous samples are referred
to: The stated 0.17 cfm is too high for the FIDs.”
Recommendation
It is recommended that the following clarification be made:
1) Specify that 0.17 cfm is the minimum flow rate for all
NOx, CO and co 2 measurements.
2) Specify a minimum FID and HFID flow rate of 4 cfh (0.067
cfm).
Comment
General Motors —— has suggested rewording §86.13781(b)(7) as
follows: “...sample filter into each of the filter holders...”
Recommendation
It is recommended that the above rewording be adopted to be
consistent with the conunent on filter holders.
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Comment
General Motors —— has recommended rewording the last sentence of
the NOTE in §86.137—81(b)(1l) to: “. . .rerun with a lower flow
rate, or larger diameter filter, or both.”
Recommendation
It is agreed that the above rewording is more proper than the
current wording of this sentence. It is therefore recommended that
the above wording be used.
Comment
General Motors —— has commented that it is not clear what humidity
measurement is required in §86.142—81(i).
Recommendation
Reference to humidity measurement is a typographical error.
This section should read as follows: “Recorder charts: Identify
zero, span, exhaust gas, and dilution air sample traces.”
Comment
General Motors —— has commented that there is no need to obtain a
record for the pressure drop across a CFV as required by §86.142
81(e).
Analysis and Recommendation
No change to §86.142—81(e) is recommended because the pressure
drop record is needed to insure that critical flow was maintained.
Other methods of critical flow determination may be available, but
monitoring the pressure ratio is the most direct and also is
easiest.
Comment
General Motors —— “The background particulate level, even though
low at EPA, contributes to measured vehicle particulate level and
should be subtracted in all cases.”
Analysis and Recommendation
No change to the proposed handling of the background correc-
tion is recommended. This correction depends upon an accurate
measurement of the dilution ratio during the test. This in turn
requires an accurate measurement of the volume of dilute air (or
exhaust) since the emissions—based to dilution—ratio formula
specified in the Federal Register is not valid for diesel vehicles.
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Dilute air flow measurements are very difficult and expensive to
make, and therefore is not considered worthwhile in view of the
very low background particulate levels in most laboratories.
Comments
General Motors —— “The equations in (b)(6) and (b)(7) [ 86.145—8l]
assume that a gas meter will be used for the flow measurement
device. We recommend removing this text and replacing it with
‘calculate the particulate flow using the proper equations for the
flow instrumentation which is used. In the case of a gas meter,
perform the following calibration technique.’”
Analysis and Recommendation
It is not agreed that the referenced equations assume that gas
meters will be used. The equation assumes only that a volumetric
flow measurement will be made. Use of a gas meter is just one way
to obtain this type of flow measurement. A time integration of
the output of a constant volume flow rate instrument is another way
to obtain the desired flow measurement. Therefore, no change to
the equations in §86.14581(b)(6) or (b)(7) should be made.
Comment
Ford —— “The proposal ignores the difficulty introduced by specify-
ing a three—bag FTP with a filter collected for each bag. The
probability of consistently acquiring three valid filters consecu-
tively in vehicle testing is low, except in the hands of personnel
trained to a degree not feasible for widespread use of the method.”
Analysis and Recommendation
It is recommended that the three—filter procedure be retained.
This three filter procedure is necessary so that the cold start and
hot start particulate measurements can be properly weighted. The
only alternative to this procedure is to use the four—bag/2filter
proposed in the Draft Recommended Practice published in March,
1978. There was widespread industry objection to this procedure
because of the extra time involved in driving two complete LA—4
cycles, and also because of the 8ubstantial computer reprogramming
that would be required. Most manufacturers recommended keeping the
particulate measurements consistent with the gaseous measurements.
The training of technicians is not considered to be any more
extensive than that required for gaseous emissions. Measurement
experience at EPA indicates that test—to—test variability is
generally less than 5 percent of mean measurements using the three
filter procedure. This compares very favorably with the varia-
bility of the other regulated emissions.
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Comment
Ford —— “The requirement on page 56 of the proposal for +1 micro-
gram filter weighing accuracy cannot be justified for sample
weights of 2 to 7 tug.”
Analysis and Recommendation
No change to the balance specification is recommended. The
one microgram specification is intended to provide the capability
to keep the contribution of the filter associated weighing and
stabilization (mainly humidity) errors to one percent or less. To
do this requires the capability of detecting day—to—day reference
filter weight changes of +20 micrograms (1 percent of the minimum
filter loading). This in turn requires a balance with at worst one
microgram capability. The +10 mg accuracy recommended by Ford will
not provide the necessary capability.
Comment
Chrysler —— “In addition, a new test requirement for fuel drain,
refuel, and preconditioning is added which will double or triple
the per—test costs.”
An a lys is
This comment is not clear and therefore no meaningful response
can be given.
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VIII. Miscellaneous
All of the major issues of this specific rulemaking have been
examined in the previous sections. This section includes the many
general comments received about the light—duty diesel vehicle, as
well as some minor specific comments that were not covered in the
previous sections.
A. Advantage of the Diesel Engine
Comments
Council on Wage and Price Stability —— “Because the proposed
standards may discourage the development and spread of diesels, we
wish to point out the advantages of diesels —— some of which are
well known, others of which are less so —— and hence indicate why
this possible discouragement of diesel usage concerns us. Perhaps
best known is the superior fuel economy aspect of the diesel....
Overall, the general rule is that a diesel vehicle will have a
25—3O h fuel economy advantage over a comparably perforinirtg gasoline
engine vehicle. . . .A second advantage of the diesel lies in the
environmental area and should be of particular interest to EPA.
Diesels emit far less hydrocarbon (HC) and carbon monoxide (co) in
the exhaust than do comparable gasoline engine vehicles. This is
due to the lean—burn characteristic of diesels. . . .Another favorable
environmental aspect of the diesel which is less widely known is
that its use and fueling involve much less HC evaporative emissions
than occurs with gasoline engine vehicles. Diesels have no carbur-
etors, and diesel fuel is much less volatile than gasoline. These
reductions in evaporative emissions are substantial. .. .A third
favorable aspect of the diesel, which seems to have been neglected,
it is superior safety in the event of a crash. Since diesel fuel
is less volatile, the likelihood of a fire in the event of a crash
is much reduced.”
Department of Energy —— “The EPA Draft Regulatory Analysis and the
Notice of Proposed Rulemaking contain little discussion of the
energy conservation aspects of diesel engine use. However, this is
one of the criteria under Section 202(a)(3)(A)(iii) which must be
considered. Questions by the EPA hearing panel members during the
public hearings seem to indicate that EPA anticipates little energy
savings due to introduction of diesel engines. This belief appears
to be based on the assumptiOn that the use of diesel engines will
simply displace other fuel saving technology (particularly in large
cars) since the Department of Transportation (DOT) analysis has
shown that diesels will not be required to meet the corporate
average fuel economy (cAFE) 27.5 mpg standard in 1985. This overly
simple view of the conservation impacts of diesels ignores a number
of facts:
— Manufacturers of diesel—powered cars are presently above the
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CAFE requirements, in part due to the use of diesel engines.
Thus, energy savings are already being derived by the use of
diesels.
— Diesel engines, particularly in large cars, may be a lower
cost way of making fuel economy gains thus leaving the manu-
facturer resources that can be devoted to other fuel economy
improving technologies.
— Significant improvements in light—duty truck fuel economy will.
be dependent in part on the use of diesel engines.
— The setting of standards requiring fuel economy improvements
beyond 1985 will also be dependent, in large part, on diesel
engines.
— For a given level of EPA measured fuel economy, the actual
on—road mpg performance for a diesel will be higher than a
gasoline—powered equivalent car. The latest DOE analysis
indicates that the shortfall between EPA and on—road fuel
economy for diesels is about one—half that of a gasoline—
powered vehicle. This means a car with an EPA rating of 27.5
mpg is getting 24.8 mpg on—road for diesels compared to about
21.5 mpg for gasoline cars. This differential represents
energy savings directly attributable to diesels even under
the assumption that current fuel economy standards remain
unchanged.
In view of the above, we believe that overall energy conser-
vation considerations require that these particulate standards not
limit the use of diesel engines, particularly in larger cars or in
light trucks. These two vehicle types are precisely the areas
where the largest energy conservation gains can be made.”
Congressman John D. Dingell —— “ [ un view of the fuel economy
standards, the Large diesel engine currently is the only means
readily available for manufacturers to continue to offer through
the mid—1980’s the family size, although down—sized, six—passenger
cars. The need for six—passenger vehicles will continue, even if
such new vehicles are not available. In that case, the public will.
simply extend the life of existing six—passenger vehicles, vehicles
which are far less fuel efficient and somewhat less clean burning
in terms of controlled emissions. I am sure it is obvious to you
that many families can only afford one vehicle for family daily use
and weekend or vacation travel. En several cases this requires the
full or intermediate sized vehicle for carrying family members and
equipment. In several additional. cases, the use of such vehicle is
required for towing trailers, boats, or other recreational equip-
ment. . . . It is, therefore, most important that your review of the
statements on the proposed standards be cautious.”
An a iys is
EPA agrees that there are definite advantages of the diesel
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engine. Since it has been established that most manufacturers
intend to meet the CAFE standards and not greatly exceed them,
regardless of the breadth of the dieselization programs, dieseli-
zation will. not provide a 25 to 30% fuel savings on a fleetwide or
national basis. Still, as the Department of Energy (DOE) and
others have pointed out, the diesel does provide fuel conservation
benefits due to its smaller shortfall between EPA projected fuel
economy and in—use fuel economy, and the likelihood that some
manufacturers will exceed the CAFE standards to some extent.
Diesel do emit lower levels of CO and evaporative HC emissions, but
they are not expected to emit any less exhaust HC emissions; all
light—duty vehicles must meet a 0.41 g/mi (0.25 g/km) exhaust HC
standards beginning with the 1980 model year. It is also accepted
that diesels are far less likely to catch fire during crashes due
to the lower fuel volatility. On the other hand, there are also
disadvantages of the diesel in addition to the considerably greater
particulate emissions. it appears to be more difficult to meet the
statutory 1.0 g/mi (0.62 g/km) NOx standard with diesels, and they
have greater noise, odor, and smoke problems than do gasoline
vehicles.
EPA has not considered the general question of the societal
desirability of the Light—duty diesel vehicle, because, as dis-
cussed in Section IV, the diesel particulate standards will not
restrict light—duty diesel production. They will only force
light—duty diesel vehicles to meet the particulate level achievable
by the highest—emitting light—duty diesel utilizing the best
available control technology. We have considered the specific
effects that the particulate standards would have on fuel economy,
other emissions, and safety.
It is ironic that Congressman Dingell advises EPA to be
“cautious” with regards to the diesel particulate reguLations.
Although we have consciously abstained from any overall judgment of
the diesel, EPA has recommended caution to the light—duty manufac-
turers until the results of the many diesel health effects research
programs have been analyzed. The possibility that diesels might
pose a carcinogenic threat demands caution. Nevertheless, EPA has
kept these recommendations independent of the diesel particulate
regulations.
B. Investment Decisions
Congressman Andrew Maguire —— “Automakers ought to proceed care-
fully. It makes little sense to spend immense amounts of capital
on conversion to diesel, nor does it make much sense to retrain
mechanics or reequip service stations to handle a new technology
when this may cause major damage to the nation’s efforts to clean
up its air and may require as a result further restrictions.”
East Michigan Environmental Action Council —— “(W]e are seeing an
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incredible Line of reasoning which suggests that the careful
approach would be to go slow with diesel regulations, so as not to
‘kill’ the diesel. Again, we would Like to make clear that perhaps
and ‘early abortion’ would be more palatable now than a ‘thera-
peutic euthenasia’ later, once ‘sufficient evidence’ has accumu-
lated. It is obvious that the industry is poised on the brink of a
huge investment, an investment which would surely work against
future attempts to be objective about the diesel. We maintain that
the ‘careful’ approach would be to delay the investment rather than
the standards.”
Analysis
As has been emphasized many times, EPA has not made the final
decision as to the acceptability of the light—duty diesel vehicle;
such a decision must await the completion of the many diesel health
effects programs now underway. The diesel particulate regulations
will not force any diesel models out of production, unless the
manufacturer is unwilling to reduce the particulate emissions of a
model to an acceptable level. We have advocated caution on the
part of the diesel manufacturers, since there is a possibility,
once the health effects data are in, that a decision will be made
to restrict diesel production.
C. Anti—competitive Standards
Comment
Volvo — — “Volvo believes that the very low particulate standards
proposed by EPA will be anti—competitive in nature because they
favour the largest manufacturers with a wide model range, and
create extraordinary difficulties for the smaller manufacturers
with a limited model range.”
Analysis
EPA disagrees with Volvo on this issue. The manufacturer with
a wide model range would have a greater advantage under an average
particulate standard because it could take full advantage of the
extra flexibility by trading—off one model’s low emissions for
another model’s higher emissions. EPA maintains that the advantage
of a wide model range is minimized by individual vehicle standards,
since such trading—off is not possible. Volvo’s support for the
CAPS proposal (see Section VIB) and opposition to the individual
vehicle standards would seem to be more a function of the numerical
stringency of the two approaches than of their effects on competi-
tion.
D. Higher Standards Due to Test Procedure
Comment
Fiat —— commented that the 1981 standard ought to be increased to
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account for the higher efficiency filters chat would be required to
be used in certification testing, Fiat claimed the EPA baseline
test data were obtained with lower efficiency filters.
An a ly s is
Fiat’s claim has no basis in fact. The 1979 certification
particulate baseline data were all taken with fluorocarbon—coated
glass fiber filters, the type that will be used by EPA for certi-
fication. The low efficiencies that Fiat obtained for its fluoro-
carbon—coated glass fiber filters, which cause Fiat to comment as
it did, were due to its usage of glass fiber back—up filters and
thus were erroneously low. This issue is dealt with further in
Section VI lE.
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