TRADEOFFS
ASSOCIATED WITH POSSIBLE AUTO EMISSION STANDARDS
A Report to the Administrator
Environmental Protection Agency
Prepared by
Emission Control Technology Division
Mobile Source Pollution Control Program
February 1975
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PROPERTY OF:
NATIONAL VEHICLE AND FUEL EMISSIONS
LABORATORY LIBRARY
2000 TRAVERWOOD DRIVE
ANN ARBOR, Ml 48105
TRADEOFFS
ASSOCIATED WITH POSSIBLE AUTO EMISSION STANDARDS
A Report to the Administrator
Environmental Protection Agency
Prepared by
Emission Control Technology Division
Mobile Source Pollution Control Program
February 1975
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CONTENTS
1. INTRODUCTION
1.1 Purpose of the Report
1.2 Methodology
2. SUMMARY AND CONCLUSIONS
2.1 Summary
2.2 Conclusions
2.3 Discussion of Conclusions
3. IMPACT OF EMISSION CONTROL
3.1 Fuel Economy Impact
3.2 Cost Impact
3.3 Sulfate Emission Impact
4. POST 1975 SCENARIOS
4.1 Suspend and Freeze @ 1.5, 15, without Catalysts
4.2 Suspend and Freeze @ .9, 9
4.3 Suspend for 1 yr. @ .9, 9, Hold .41 3.4, 2.0
4.4 Deny, Hold 2.0 NOx through 1980
4.5 Deny, Push for Low NOx
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SECTION 1
INTRODUCTION
1.1 Purpose of the Report
This report has been prepared to provide the Administrator with our
best judgement of what the impacts are likely to be of possible
suspension decisions and recommendations to the Congress he might
make. The impacts considered by the report team are strictly those
which are the direct results of changes in emission control technology.
These impacts include:
1. Vehicle cost changes
2. Vehicle fuel economy changes
3. Unregulated pollutant level changes
Indirect impacts that changes in emission control technology might
cause were not dealt with. Impacts such as:
1. Changes in vehicle miles traveled (VMT)
2. Changes in ambient air quality
3. Changes in market demand
were considered beyond the scope of this report and may be better
analyzed by others in the Agency.
1.2 Methodology
For each of the possible decisions and recommendations which the report
team considered to be of greatest interest to the Administrator, the
expected direct impacts were determined as a function of time. Five
Scenarios are depicted which are the estimated results of five different
decisions and recommendations the Administrator might make:
1. Suspend 1977 standards, set interim standards and recommend
a freeze at 1.5 HC, 15 CO, implement a crash program that
results in the elimination of catalysts from 1977 models.
2. Suspend 1977 standards, set interim standards and recommend
a freeze at .9 HC, 9.0 CO.
3. Suspend 1977 standards, set interim standards of .9 HC, 9 CO,
2.0 NOx,recommend .41 HC, 3.4 CO, 2.0 NOx for 1978 through
1980.
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4. Deny, recommend 2.0 NOx through 1980.
5. Deny, recommend lowest possible NOx through 1980.
For scenarios 1 and 2, the impact of 2.0 NOx versus 3.1 NOx was considered
so insignificant compared to the impact of the other scenarios that
specific differences between these two NOx levels were not depicted.
The estimated impacts for scenarios 1 and 2 would be nearly the same
for either NOx level. However, some quantification of the expected
differences in impact of 2.0 versus 3.1 NOx is given in section 3.1
of this report.
For each scenario the report team estimated the type of emission control
systems that would be used to meet the standards, the customer first cost
of these control systems , the fuel economy of a typical car using those
control systems and the sulfate emission levels the typical car would
produce. All of these factors are shown for model years 1974 through
1980 for each of the five scenarios.
The impact of sulfate emission standards, or some other program to
reduce vehicular sulfate levels, is considered for each scenario in
addition to a "no sulfate control" case. Projections of tailpipe
sulfate levels for scenarios 2 through 5 are made for three different
assumptions:
1. No program to reduce the sulfur level of unleaded gasoline,
no vehicular sulfate control, lead phase-down.
2. A blending and allocation program to reduce the sulfur
level of unleaded'gasoline, modified lead phase-down regulations,
no vehicular sulfate control.
3. A moderate blending and allocation program to keep the
sulfur level of unleaded gasoline at one half of pool levels,
modified lead phase-down regulations, and a moderate vehicular
sulfate control program implemented.
The control system usage projections are based on industry estimates
of the type of systems they are planning to use for various emission
levels and the judgement of the report team.
Cost estimates are based on Section 4 of Automobile Emission Control
The Technical Status and Outlook as of December 1974 (1).* The cost
* Numbers in parentheses designate references at end of report.
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estimates from that report were based on industry projections and the
findings of the National Academy of Sciences and are expressed as the
cost difference over uncontrolled vehicles.
Sulfate emission estimates are based on experimental work performed
by the EPA Ann Arbor laboratory and Exxon Research and Engineering
and studies of sulfur in gasoline performed by the M.W. Kellogg Co.
(3) (4).
Fuel economy estimates are based on industry data on prototype cars,
and analysis of EPA certification data for model years 1974 and 1975 (2)
All fuel economy estimates are shown relative to the typical 1974 car.
CHANGES IN FUEL ECONOMY FOR THE VARIOUS SCENARIOS ARE THE CHANGES DUE
ONLY TO THE IMPACT OF EMISSION CONTROL HARDWARE ON ENGINE EFFICIENCY.
The possible impacts of model mix shifts, weight reduction programs,
aerodynamic drag changes and other such factors are not considered.
These factors which were not considered could have more impact on
vehicle fuel economy than the changes in emission control systems.
Previous analysis has clearly shown that the fuel economy level
of nominally identical cars meeting the same emission standard can
be significantly different. This situation occurs because different
manufacturers place different levels of interest in fuel economy.
Fuel economy can be traded-off against first cost and driveability.
Rather than attempt to deal with this problem of differences in
corporate philosophy with respect to fuel economy, the report team
assumed that during the time period from 1977 through 1980 sufficient
pressure (public or regulatory) would be on the industry to cause all
manufacturers to place a .greater emphasis on fuel economy than has
been the case in the past, even at some trade-off in first cost. This
assumption is somewhat hazardous because the variance in fuel economy
that currently results from differences in corporate philosophy is
another factor that has more impact on vehicle fuel economy than
changes in emission control systems and emission standards.
In summary, the report team can project the changes in vehicle fuel
economy related to engine efficiency changes with some confidence
under the assumptions we have made. Since, however, the impact of
future emission standard scenarios on fuel economy is small compared
to other factors, the probability of accurately projecting the
absolute value of the fuel economy of future model year cars based
only on the level of future emission standards is small.
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SECTION 2
SUMMARY AND CONCLUSIONS
2.1 Summary
Figures 2.1 and 2.2 summarize the report teams' projections for the
first four scenarios of Section 1. It can be observed from Figure 1
that the first cost difference between the various scenarios ranges from
a maximum of $160 in the 1977 model year to $180 in 1980. Table 1
shows the control system usage on which the cost estimates are based.
The difference in fuel economy between various scenarios ranges from
9% in 1977 to 5% difference in 1980. On this point the report teams
estimate is in agreement with the findings of the EPA/DOT Fuel
Economy Study (5) and the testimony of DOT at the suspension hearings.
The technology can be available by 1980 to produce engines that are
essentially unaffected by differences in emission standards between 1.5
15, 3.1 and .41, 3.4, 2.0. The 5% and 2.5% higher fuel economy for 1980 in
scenarios 1 and 2 respectively, results from the assumed use of leaded
fuel and one full unit higher compression ratio. The minimal dis-
advantages of the systems that require unleaded fuel may be reduced
or eliminated by future engine modifications that facilitate the use
of higher compression ratio.
Sulfate emission levels are estimated to range from a high of .05 grams
per mile for the systems which use high sulfur fuel and oxidation
catalysts with air injection to a low of less than .005 gpm which can
be met by non-catalyst systems or catalyst systems if a blending and
allocation program is implemented. With minimal control over unleaded
fuel sulfur levels and moderate vehicular sulfate control, levels of
H-SO, emission of .013 gpm are considered possible at the .41 HC,
3.4 CO, 2.0 NOx levels. This level is about 80% lower than the level
assumed in the EPA sulfate issue paper officially released on
January 24, 1975.
2.2 Conclusions
With respect to the possible decisions and recommendations the Admini-
strator might make the report team concludes:
1. 1980 fuel economy is estimated to.be 7-13% better than 1975
due to engine efficiency improvements for all emission standards
between 1.5, 15, 2.0 and .41, 3.4, 2.0. With still lower NOX
levels (.8 gpm in 1980) fuel economy in 1980 will be about
the same as for 1975 models. Further reductions of NOx levels
beyond this level of 0.8 gpm would result in fuel economy
penalties relative to 1975 models.
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2. Low NOx systems below 2.0 gpm are estimated at $250 more
than '75 systems. Emission control system costs in 1980 for
the -four scenarios depicted in figure 2.1 are estimated to
be between $30 more and $150 less than 1975 systems.
3. The eventual, circa 1980, first cost and fuel economy penalties
for the 1977 statutory emission standards compared to the 1.5,
15, 2.0 level will be about $180 and -5% in economy. Due to the
use of unleaded fuel, lower maintenance cost for the 41, 3.4, 2.0
system, however, will more than counter-balance the first cost
penalty.
4. Sulfate levels will depend on the emission standard level
and the extent to which the sulfur of gasoline is reduced.
Tighter emission standards will result in higher sulfate levels
unless fuel sulfur is reduced or a vehicular sulfate control
program is implemented but significantly lower fuel sulfur
levels than were assumed in the EPA sulfate issue paper appear
to be achievable without desulfurization.
2.3 Discussion of Conclusions
A typical emission control system for a 1975 model costs about $200.
The principal components of the '75 system are engine mods, EGR and an
oxidation catalyst. Some models also use air pumps. By 1978 or 1979
the report team estimates that tighter emission standards, at least
down to .41, 3.4, 2.0 can be achieved with a less costly system. Data
available to the report team from tests run on GM, Dresser and Chrysler
systems indicate that improved carburetors calibrated for "lean burn"
should be able to meet the 1977 statutory standards with catalysts but
without EGR and air injection. Combining the lean burn approach with
improved catalysts (perhaps using less noble metal) should cost less
than current systems. The report team estimates however, that about
half of the market will not have started using the lean burn plus
oxidation catalyst approach by 1980.
As shown in Section 3, lean burn systems capable of "engine out" emissions
in the range that can be catalytically controlled to .41, 3.4, 2.0 are
equal in fuel economy to the best of the 1975 models, which is about 7%
better than the typical 1975 car. Advanced oxidation catalyst systems
also have the potential to meet .41, 3..4, 3.0 with 7% better economy
than the typical 1975 model, as is discussed in Section 3. By 1980
both lean burn-oxidation catalyst and advanced oxidation catalyst systems
can be "optimized" for fuel economy. The only emission control related
fuel penalty is likely to be due to the lower compression ratio required
for the use of lead-free fuel. Lean burn systems without catalysts
may be able to achieve about 5% better fuel economy by using higher
compression ratio and leaded fuel. The report team concludes that non-
catalytic, lead tolerant systems could be optimized for fuel economy
for emission standards as low as .9, 9, 2.0.
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With long term emission standards of .9, 9, 2.0, several manufacturers
can be expected to eliminate catalysts and use leaded fuel by 1980.
This will cause first cost to be lowered compared to systems that use
catalysts but lifetime maintenance costs will be more than significantly
lower for the catalyst system because of unleaded fuel usage. The vehicle
using unleaded fuel will need fewer spark plug changes and, most
importantly, few exhaust system replacements. The report team believes
a significant fraction of the market (approximately 50%) will stay with
catalysts and unleaded fuel at the .9, 9, 2.0 level unless action taken
by the government prevents them from doing so. Total operating costs
(including fuel economy) of the catalyst versus non-catalyst system
will be so close that one technology will not have a clear advantage
over the other. The catalyst systems may be used by some for better
driveability. At .9, 9, and 2.0 the catalyst system may need very
little noble metal by 1980, and if fuel sulfur levels are reduced,
the use of base metal catalysts, which could be cheaper and have less
impact on the balance of payments, might be possible.
With long term emission standards of 1.5, 15, 2.0, nearly all manu-
facturers might be expected to eliminate catalyst usage by 1980 of their
own volition. The report team estimates, however, that a significant
fraction of the market would 'Still use catalysts at these levels
in 1977 unless government action prevents it, System costs by 1980
would be about $90 less than with standards of .9, 9, 2.0 and about
$180 less than with standards of .41, 3.4, 2.0. Fuel economy should
be equal to that achievable at the .9, 9, 2.0 level of standards or
about 5% better than with standards of .41, 3.4, 2.0.
Emission standards designed to minimize NOx emissions will reduce the
gains in fuel economy that are possible between now and 1980. The level
of cost and fuel economy associated with a low NOx emission scenario will
depend on just how low the NOx standard is made. The report team
selected a scenario that is estimated to keep fuel economy well above
the 1974 level. .8 gpm NOx by 1980 should be possible with about 5-10%
less economy than is possible with the other scenarios. The degree of
this fuel penalty, however, is strongly dependent on model mix. If
the market shifts toward smaller cars then it may be possible to achieve
about .8 gpm NOx with little or no penalty compared to the higher NOx
scenarios. Our estimate of 5-10% fuel penalty assumes no shift to
small cars.
Sulfate emission levels depend on the level of sulfur in the fuel and
the efficiency with which the vehicle converts SO- formed during
the combustion process to S0_. Oxidation catalysts with air injection
have been shown to increase the S0~ to S0» conversion from the l%-3%
that occurs with non catalytic systems to 20-30%. With the fuel sulfur
level typical of current gasoline this results in tailpipe emissions
of about .02 or .03 grams per mile of sulfuric acid, H-SO,. The EPA
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issue paper on sulfates projected a potential health problem if .05-07
gpm H-SO, occurs. The .05-.07 gpm emission rate was based on the assumption
that unleaded fuel would eventually become as high in sulfur content
as the current total gasoline pool is. A study performed for EPA by
M.W. Kellogg indicates, however, that this does not necessarily have
to be the case. As discussed in Section 3.3 of this report the sulfur
level of unleaded fuel can be cut drastically using a blending and
allocation program. In the short term, the cost of providing nearly
sulfur-free unleaded fuel will depend on the degree of lead phase-down
required. If the lead phase-down originally promulgated by EPA (and
since over turned by the Court of Appeals) is modified it should be
possible to attain fuel sulfur levels approaching zero. Even with a
modest blending and allocation program (assuming a stringent lead phase-
down) and moderate vehicular sulfate control, tailpipe sulfate emissions
80% lower than those projected in the EPA sulfate issue paper can be
achieved while meeting the .41, 3.4, 2.0 levels. A moderate vehicular
control program might consist of catalyst reformulation and air injection
modulation. Preliminary data indicate catalyst reformulation could cut
the SO.-SO. conversion efficiency to half of that projected in the
issue paper. If further reductions are necessary, traps should be
available before 1980 that are 90% efficiency.
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Fig. 2.1 Summary of the Scenarios
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$400
m $300
3
2 $200
h
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41
JS
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Scenario 1, Suspend & Freeze @ 1.5, 15, Mo Catalysts
Scenario 2, Suspend & Freeze @ .9,9.
Scenario 3, Suspend @ .9, 9 for 1 yr. hold .41, 3.4
2.0 from 1978 through 1980.
Scenario 4, Deny and Hold 2.0 NOx
$400
$300
$200
$100
1.25
1.20
1.15
1.10
1.05
1.00
1974
1975
1976
1977
1978
1979
1980
Figure 2.2 Summary of Scenarios
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Table 1
Projected Emission Control System Usage
Scenario (Applicable Emission Standards in Parentheses)
Scenario
Model Year
1974
1975
1976
1977
1978
1979
1980
EM-1
(3.0,2.8,3.1)
OC-1
(1.5,15,3.1)
OC-1
(1.5,15,3.1)
LB-1 & EM-2
(1.5,15,3.1)
LB-1 & EM-2
(1.5,15,3.1)
LB-1
(1.5,15,3.1)
LB-1
(1.5,15,3.1)
EM-1
(3.0,28,3.1)
OC-1
(1.5,15,3.1)
OC-1
(1.5,15,3.1)
OC-2
(.9,9,2.0)
LB-2 & OC-1
(.9,9,2.0)
LB-2 & OC-1
(.9,9,2.0)
LB-2 & OC-1
(.9,9,2.0)
EM-1
(3.0,28,3.1)
OC-1
(1.5,15,3.1)
OC-1
(1.5,15,3.1)
OC-2
(.9,9,2.0)
AOC-1
(.41,3.4,2.0)
AOC-1
(.41,3.4,2.0)
LBOC & AOC-2
(.41.,3.4,2.0)
EM-1
(3.0,28,3.1)
OC-1
(1.5,15,3.1)
OC-1
(1.5,15,3.1)
AOC-1 & OC-2
(.41,3.4,2.0)
AOC-1
(.41,3.4,2.0)
LBOC & AOC-2
(.41,3.4,2.0)
LBOC & AOC-2
(.41,3.4,2.0)
EM-1
(3.0,28,3.1)
OC-1
(1.5,15,3.1)
OC-1
(1.5,15,3.1)
AOC-1 & OC-2
(.41,3.4,2.0)
AOC-1
(.41,3.4,2.0)
DC-1
(.41,3.4,1.2)
DC-1
(.41, 3. 4, .8)
Legend
EM-1 (engine mods.) Calibration changes,minor combustion chamber geometry changes,
valve timing changes, EGR, etc.
EM-2 EM-1 with advanced cold start emission devices and air injection
OC-1 (Oxidation catalyst system) engine mods, EGR, no air injection
OC-2 OC-1 with air injection
AOC-1 (advanced oxidation catalyst system) OC-2 with start catalyst and
advanced cold start emission control devices.
AOC-2 OC-2 with advance cold start devices, improved main catalyst over AOC-1
LB-1 (lean burn) improved carburetion and intake manifolding
LB-2 LB-1 with partial thermal reactors
LBOC LB-1 with oxidation catalyst (no air pump, no EGR)
DC-1 (dual catalyst) NOx catalysts, oxidation catalyst, advanced cold start
emission control systems, air injection
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SECTION 3
BACKGROUND
3.1 Impact of Emission Control
3.1.1 Fuel Economy Impact
Some of the specific emission control related factors that affect both
the emissions and fuel economy of current engines are air/fuel ratio
and air/fuel ratio control, spark timing and spark timing control, degree
of exhaust gas recirculation (EGR) and methods of EGR control, choke
time, calibration and quick warm-up device control, intake air temperature
control, choice of exhaust gas aftertreatment type, and system optimiza-
tion. Table 3.1 gives the general effects these factors have on fuel
economy and exhaust emissions. The varied effect of different emission
control techniques such as the ones listed in Table 3.1 indicate that
it is not enough to know the directional effect of a system change on
exhaust emissions to deduce the directional change in fuel economy.
Some of the most effective control techniques, such as catalytic con-
verters, have no effect on fuel economy. The use of such devices allows
the "decoupling", as NAS put it (7), of emission control and fuel
economy. Aftertreatment devices such as catalysts and thermal reactors
only affect fuel economy to the extent that engine calibration changes
are made to optimize their effectiveness. With lean thermal reactors or
catalysts, low emission levels can be achieved using engine calibrations
for optimum fuel economy.
The net effect on fuel economy of a given emission standards depends on
the combination of control techniques used to achieve compliance. Analysis
of EPA certification data has clearly shown that the fuel economy per-
formance of nominally identical cars (e.g. same weight, engine size,
axle ratio, etc.) can be significantly different while the emissions are
nearly the same. The difference in fuel economy is the result of the
difference in the usage of fuel efficient control technology. At a fixed
emission level fuel economy is a function of the usage of fuel efficient
control technology.
At the 1974 emission standards of 3.0 HC, 28. CO and 3.1 NOx the
typical car suffered a 12% loss in fuel economy compared to uncontrolled.
This loss was due to the selection and use of emission control techniques
such as spark retard, which reduced engine efficiency. It is important
to point out that not all cars showed the losses of the "typical" car.
As shown in Figure 3.1, the heavier vehicles (which needed more emission
control) had losses greater than the average, while the lighter cars
were able to meet the standards with no fuel penalty.
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Table 3.1
Impact of Various Emission Control
Techniques on Fuel Economy
Technique.
Pollutants Controlled
1. Retarded Spark Timing
2o Rich air/fuel ratio
3, Lean air/fuel ratio
4c Port EGR
5. Proportional EGR
6. Quick Heat Intake Manifold
w/fast choke
7. Heated intake air
8. Air injection
9o Oxidation catalyst
10. Reduction catalyst
11. Thermal reactor
12. Reduced compression ratio
Fuel Economy
Effect
HC, NOx
NOx
HC, CO, NOx
NOx
NOx
HC, CO
HC, CO
HC, CO
HC, CO
NOx
HC, CO
HC, NOx
Negative
Negative
Positive
Negative
None or Positive
Positive
Positive
Almost none
None
None
None
Negative
FUEL ECONOMY vs. VEHICLE WEIGHT
§
30
25
20
15
10
1957-1967 Vehicles
1974 Vehicles -__.
——o
Note2 MPG=
.55
75FTP
.45
HWC
2000 2500 3000 3500 4000
Inertia Weight
4500 5000
5500
Figure 3.1
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At the 1975 Federal interim standards of 1.5, 15, 3.1 it has been
demonstrated that the use of oxidation catalyst systems allows fuel
economy to .be optimized except for a minor penalty due to the lower
compression ratio required with unleaded fuel. Figure 3.2, taken from
an SAE paper by GM (8) shows that "economy optimization" has been
achieved on 1975 GM cars. The point labeled, "Potential Best Economy
(No Emission Control)" and the point at the level labeled, "Gain
adjusted for Weight and Compression Ratio" are showing the same
economy. The lower compression ratio used on catalyst cars is
estimated by GM to cause only a 2% loss in economy. Quoting from the
paper, "For 1975, use of the oxidizing catalytic converter for after-
treatment of HC and CO is seen to allow a recoup of virtually all
emission-related fuel economy losses - except for the lowered
compression ratio associated with low octane fuel."
Figure 3.3 compares the best of the 1975 model cars to the '57-'67
uncontrolled models. In the weight class region where GM sells most
of their cars it can be seen that the fuel economy of the '75 models
and uncontrolled cars are just about the same. In the lighter weight
categories the best 1975 models are significantly better than
uncontrolled cars because many small uncontrolled cars were not
optimized for fuel economy. Many used excessively rich air-fuel
ratios for better driveability and power.
Figure 3.4 compares the best of the 1975 models to the average of
the 1974 cars. The report team agrees with GM (8) that the best
1975 models are essentially optimized for fuel economy. Comparing
the curve for '75 models with the curve for the 1974 models, the
report team estimated that the average optimized car could do 20%
better in fuel economy than the average 1974 model car.
The levels of 1.5 HC, 15. CO, 3.1 NOx are -83%, -83%, and -11%
respectively lower than the levels of uncontrolled cars and yet the
selection of fuel efficient emission control technology has allowed
these levels to be achieved (at least by one manufacturer) with
essentially no fuel penalty. There is no technical justification for
projecting that the capability for meeting emission standards
without fuel penalty stops at 15., 15, 3.1. Work reported,,by GM (9)
showed that NOx levels below 1.5 gpm could be achieved without fuel
penalty with the use of proportional EGR (PEOR) and careful optimizing
of spark timing and air/fuel ratio. The disadvantage of the PEOR/
optimization method of achieving low NOx emissions is that HC and CO
levels rise. A 5000 pound GM test car that achieved 1.1 gpm NOx'
had HC and CO emissions of 2.0 and 20. GM's production catalyst for
1975 would reduce these levels to .70 gpm HC and 7.0 gpm CO at
50,000 miles. The fuel economy of this car was 12.8 mpg on the urban
test which is'17% higher than the average uncontrolled car in this
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I Economy Tmuls
CKUMWM IdAIN/lOtSI IN CM Cirf-SVftlHtMt SCMtOULt KOHOHY
.10 T /"O""" «" «"*.»•
1970 1971 1972 1973 1974 1975
MODEL YEAR
AMALYIK O* »UIL fCONOMT CHANOU:
• ItTt PAIN HMULTS FHOM IMQIMI OTrtMltATION
(lOH. MARK ANO A/» MATIO WITM CATALYTIC CONV(HTin)
•ATIO AWMOACMIt'ltla »I»T ICOMOMY
Figure 3.2
30
25..
B
O
<^ ?O -
&4
0)
20
15..
Best 1975 Cars
Uncontrolled Cars
Notes MPG=
.55
75PTP HWC
2000 2500 3000 3500 4000 4500 5000 5500
INERTIA WEIGHT (Ibs)
Figure 3.3
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Figure 3.4
c
o
0)
O
^
Average 1974'^
Note: MPG=
.55 + .45
75FTP HWC
2000 2500 3000 3500 4000 4500 5000 5500
INERTIA WEIGHT (Ibs)
X
Advanced Lean Burn System versus 1974 Average
Figure 3.5 and Best 1975 Data
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weight class, 6% better than the average 1975 GM car in this weight class.
Without advances in catalyst technology it appears that fuel economy can
at least be optimized at the .9, 9, 2.0 level based on the results of
tests like the one shown by GM in reference 9.
Below .9, 9, 2.0 the capability to avoid fuel economy penalties will
depend on the development and implementation of more advanced emission
control technology. It became apparent during this year's suspension
hearings that one area where significant improvement is possible is
catalyst efficiency. Two approaches looked promising, start catalysts
and improved main catalysts. The kind of catalyst efficiency improve-
ments already demonstrated by GM and the use of a "switched-out" start
catalyst is projected to reduce the emissions of the low NOx, fuel
economy optimized car from reference 9 to levels of .43 HC, 3.2 CO,
1.1 NOx at 50,000 miles. Such a system with NOx adjusted upwards would
have a high probability of certifying at .41, 3.4, 2.0 with optimized
fuel economy. The report team estimates that by 1980 the .41, 3.4,
2.0 standards will be achievable with optimum fuel economy even
without the use of start catalysts. Two ways this might be achieved
could be:
1. The PEGR/spark/air-fuel ratio optimization approach with
further improved main catalyst efficiency.
2. The lean-burn approach with oxidation catalyst after-
treatment .
The Dresser carburetor data from reference indicates this latter
approach may be feasible. Dresser prototypes are already low enough
to meet .41, 3.4, 2.0 with oxidation catalysts and reference 6 shows
that the fuel economy of such a system would be as good as the best
1975 models (i.e. no fuel penalty). Figure 3.5 shows this graphically.
To achieve .41 HC and 3.4 CO with NOx levels below 1.5 it may be
beneficial to use NOx catalysts. While the feed gas of the car
described above may be NOx catalyst compatible, the addition of
NOx catalysts to the system may degrade the HC and CO control
efficiency to some extent because of the thermal inertia then will
add to the system. This added thermal inertia may require the start
catalyst to be left on stream longer than without NOx catalysts and
this would result in degraded start catalyst efficiency at high
mileage. It may be necessary to use some kind of fuel inefficient
approach, such as spark retard, to make up for lost HC control.
Assuming that serious efforts are made by the manufacturers to
achieve good fuel economy, the report team has estimated the type
of systems that would be likely to be marketed given different
assumptions about the time phasing and level of emission standards.
-------
The estimates appear in Table 3.2. We are projecting that the system
which could be initially used for any particular emission standard will
evolve into a simpler and less expensive system with time. Down to
standards as tight as .9 HC, 9.0 CO, 2.0 NOx we believe a significant
fraction of the market will eventually use non-catalytic hardware.
At the .41, 3.4, 2.0 level and lower we believe the catalyst will
continue to be a part of any system designed with fuel economy in
mind. Alternative engines such as stratified charge were not considered
for two major reasons:
1. They will not represent a significant portion of the market
by 1980.
2. They offer only minimal fuel economy benefit unless run as
open-chamber unthrottled versions. Such versions have odor,
noise and hydrocarbon carbon emission problems and they are
significantly more expensive because of the high pressure fuel
injection systems they require.
At least down to the emission levels of .41, 3.4, 2.0 the capability
to optimize fuel economy by 1980 is projected by the report team.
It does appear however that lead time problems will result in some
fuel penalties in the interim, even at less stringent emission standards.
This is because few manufacturers have been concentrating on optimizing
fuel economy at emission standard lower than they have asked to be set
as interim standards. Notable examples are several foreign manufacturers
like Volkswagen, for instance who is already fuel economy optimized
and is projecting no penalty at .41, 3.4, 2.0.
Appendix 1 to this report summarizes the short term fuel economy
losses that can be expected based on prototype car tests.
Table 3.3 gives the report team's estimates of fuel economy relative
to 1974 models for the same emission standard/model year combinations
shown in Table 3.2.
3.1.2 Cost Impact
The system cost associated with any particular emission standard depends
on the individual components used to make up the system. There is some
difficulty in estimating costs for a particular standard because of
the several combinations of individual components capable of achieving
compliance. The component cost estimates used by the report team are
based primarily on those estimates made in reference 1. Table 3.4
is taken directly from reference 1.
Table 3.5 gives the report teams estimates of the cost associated
with the systems described in Table 3.2. As would be expected the
cost of meeting a particular emission standard decreases with time as
technology improves.
-------
Table 3.2
Projected Emission Control Systems
Applicable Standards
Model Year 3,28,3.1
1974 EM-1
1975
1976
1977
1978
1979
1980
1.5,15,3.1*
OC-1
OC-1
EM- 2 and
LB-1
LB-1 and
EM-2
LB-1
LB-1
.9,9,2.0
OC-2
OC-2
OC-2
LB-2 and
OC-1
LB-2 and
OC-1
LB-2 and
OC-1
.41,3.4,2.0
AOC-1 and
OC-2
'
AOC-1
LBOC and
AOC-2
LBOC and
AOC-2
.41, 3. 4, .4
DC
DC
DC
* No catalyst usage assumed starting 1977
Legend
EM-1 (engine mod) calibration changes, minor geometry changes
(combustion chamber shape valve timing, etc), EGR
EM-2 EM-1 with advanced cold start emission control devices and
air injection
OC-1 (oxidation catalyst) engine mods include EGR, oxidation
catalyst, no air injection
OC-2 OC-1 with air injection
AOC-1 (advanced oxidation catalyst) OC-2 with start catalyst and
advanced cold start emission control devices
AOC-2 AOC-1 without start catalyst but with improved oxidation catalyst
LB-1 (lean burn) engine mods without EGR, improved carburetion and
intake manifold
LB-2 LB-1 with partial thermal reactors
LBOC LB-2 with oxidation catalyst
DC (dual catalyst) AOC system plus NOx catalyst
-------
Table 3.3
Projected Fuel Economy Relative to 1974
Applicable Standards
Model Year
3.28.3.1 1.5.15.3.1* .9.9,2.0 .41.3.4.2.0 .41,3.4.Low NOx
1974
1975
1976
1977
1978
1979
1980
EM-1 = 1.0
OC-1 =1.14
OC-1 =1.16
EM-2 =1.03
LB-1 =1.14
avg. = 1.07
EM-2 =1.03
LB-1 =1.14
avg. = 1.11
LB-1 =1.18
LB-1 = 1.25
OC-2 =1.07
OC-2 =1.10
OC-2 =1.16
LB-2 =1.20
OC-1 =1.16
avg. =1.18
LB-2 =1.22
OC-1 = 1.18
avg. = 1.21
LB-2 =1.25
OC-1 =1.20
avg. = 1.22
OC-2 =1.03
AOC-1 =1.14
avg. = 1.09
AOC-1 =1.14
LBOC =1.18
AOC-2 =1.18
avg. =1.18
LBOC =1.20
AOC-2 =1.20
avg. =1.20
DC = 1.09
@ 1.2 NOx
DC = 1.15
@ .8 NOx
* No catalyst usage assumed starting 1977
-------
Table 3.4
Emission Control Component Costs
(Jan 75 Dollars)
Component
NAS Estimates
73 74
Range of Most
Manufacturers
Estimates
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
PCV valve
Evap Control
Transmission Controlled
Spark (TCS)
Anti-Dieseling Solouoid
Intake air heater
OSAC spark control
Hardened valve seats
Port EGR
Air system
PEGR
QHI manifold
Electric choke
HEI
Timing & other control
modulation valves
OX catalyst
NOx catalyst
Misc. mods thru '74
EFI
0 ' Sensor
3-way catalysts
Thermal Reactor
Improved Exhaust System
QA and other tests
Ox Pellet cat chg.
Mono cat chg.
EFE
Start catalyst
$3.50
$17.00
$4.50
$6.00
$4.50
$1.00
$2.00
$11.50
$52.50
$36.50
$6.00
$6.00
$11.50
$3.50
$66.50
$45.00
$19.50
$53.00
-
-
-
-
-
-
-
-
-
3.
12.
-
-
-
-
-
15.
35.
23.
-
-
-
-
80 Pellet
61 Mono
86 Pellet
78 Mono
-
120
A
97
-
-
-
-
-
-
-
2
5
7
2
5
14
25
35
4
27
2
36
75
30
250
20
175
70
30
5
29
10
-
3
- 18
- 34
6
- 12
6
2
- 61
-
-
-
9
- 116
- 33
- 300
- 178
70
- 556
- 130
- 220
- 140
40
- 39
- 77
- 178
15
-
Report Team
Estimate
3
15
5
6
5
5
2
20
40
40
10
6
30
5
80 Pellet
50 Big Monolith
60 Each
20
250
20
100
100
30
10
70
150
15
50
-------
Table 3.5
System Cost Estimates
Applicable Standards
Model Year
3,28.3.1 1.5,15.3.1* .9.9.2.0
.41.3.4.2.0 .41.3.4.4
1974
1975
1976
1977
1978
1979
1980
EM-1 = $100
OC-1 =
OC-1 =
EM- 2 =
LB-1 =
avg. =
EM- 2 =
LB-1 =
avg. =
LB-1 =
LB-1 =
$200
$190
$150
$60
$140
$150
$60
$110
$60
$50
OC-2 =
OC-2 =
.
OC-2 =
LB-2 =
OC-1 -
avg. =
LB-2 =
OC-1 =
avg. =
LB-2 =
OC-1 =
avg. =
$240
$240
$250
$90
$210
$200
$90
$200
$170
$90
$200
$140
OC-2 =
AOC-1 =
avg. =
AOC-1 =
LBOC =
AOC-2 =
avg. =
LBOC =
AOC-2 =
avg. =
$270
$340
$300
$340
$190
$270
$250
$190
$270
$230
DC = $450
DC = $450
* No catalyst usage assumed starting 1977
-------
3.3 Sulfate Emission Impact
Sulfate emission levels from automobiles primarily depend on two factors:
1. Conversion efficiency of S02 formed during combustion to
863 in the vehicles exhaust system.
2. Fuel sulfur levels.
Reductions in vehicle sulfate emissions from changes in both of these
factors appear possible without the expense of complicated vehicular
sulfate traps or extensive fuel desulfurization.
3.3.1 Fuel Sulfur Levels
Gasoline is a blend of five major refinery products-butane, alkylate,
reformate, virgin gasoline, and fluid catalytic cracked (FCC) gasoline.
The percentages of the refinery products utilized in the refinery blend
depend largely upon the desired octane of the product, the actual quantities
of each product produced, and competitive price of gasoline at the retail
level.
The first four components are inherently high in octane quality and are
more costly to produce (except for butane). The fifth component FCC
gasoline is low in octane quality but its production cost is lower.
Because of the inherent characteristics of the refinery process the first
four components are very low in sulfur content while the FCC gasoline
component is very high in sulfur content.
Historically, the low octane quality FCC gasoline has been equally
distributed between the premium and regular grades of gasoline. The
poor octane quality of this component was offset by blending in varying
fractions of the other four components and the addition of tetraethyl
lead.
The introduction of no-lead requirements and the regulations for phase-
down of lead average content in the total pool has required significant
changes in the blending programs. Currently, most refiners have elected
to blend the no-lead grade with little if any FCC stock. This is borne
out by the surprisingly low sulfur content in the no-lead grades currently
marketed as reflected by the latest MVMA gasoline survey.
This utilization of the high octane components in the no-lead grade is
possible because of low sales volume and correspondingly decreases in
sales of premium fuel which has freed the necessary blending components.
Actually, since octane must be built up in the no-lead fuel through
hydrocarbon composition alone'there is a limit to the amount of FCC
gasoline that could be utilized - a limit that in the opinion of the
report team would hold sulfur content consequently to about 0.02-0.25 wt. %.
The phase-down regulation will require increased useage of high octane
components in both regular and premium grades. By 1978, in the opinion
-------
of the report team, the refiners will face an octane shortfall which can
most readily be solved by reformation of the FCC gasoline. Such processes
require the almost complete desulfurization of feed stocks because of the
sulfur poisoning of catalysts utilized in the processes.
Consequently, if the market demand for no-lead fuel continues to grow
as EPA orginally projected and the lead-phase down regulations are success-
fully defended in the courts, the refining industry will have to begin
operation of hydrodesulfurization equipment by 1978 regardless of government
action.
A revocation of the phase-down regulations with no change in.no-lead
gasoline demand growth would delay the need for installation of reformer
capacity and desulfurization to 1980-81.
In either case without governmental action the sulfur content would be
expected to increase to a stable level of about .02-.25% by wt.l This
number is about 20to 25% lower than that assumed for the 49 state case
in the sulfate modeling studies and about 50% lower than the value
assumed for California.
The "assumption " used for the scenario presented in this report projected
a moderate blending and allocation program designed to result in the
availability of unleaded fuel of .015% sulfur by weight. This calls
for only 25% to 40% lower sulfur levels than the report team estimates
will occur without any program to lower gasoline sulfur. This can be
accomplished without desulfurization or allocation if the lead phase
down is modified or eliminated .'With the lead phase-down .015 could be
achieved with modest de-sulfurization and no allocation program or
without de-sulfurization if a program is implemented that allocated
the low sulfur fuel to urban areas.
3.3.2 Vehicular Control
Three types of vehicular control techniques for sulfate emissions are
already showing promise despite the modest level of sulfate control
technology development effort underway:
1. Catalyst reformulation
2. Excess air control
3. Traps
Catalyst reformulation and excess air control have already demonstrated
50% reductions in sulfate compared to conventional '77 prototypes with
This estimate is supported by the testimony of M.W. Kellogg Co. at the
recent sulfate hearings. Kellogg projected (TR@544) .025% as the sulfur
content of no lead fuel without installing additional desulfurization
equipment. Under this assumption the lead phase-down was not achieved
Meeting the lead phase-down would require more reforming capacity. The
use of more reformation requires more desulfurization and sulfur levels
would likely go below .025 in unleaded fuel-
-------
air injection and catalysts. Traps have shown over 90% sulfate removal
for 25,000 miles. The report team estimated, based on these promising
preliminary results, that 50% control could be achieved by 1978. The
report team considers it most likely that catalyst reformulation will
receive primary emphasis as this technique has essentially no adverse
emission control or cost impacts.
-------
SECTION 4
POST '75 SCENARIOS
Each scenario runs from model year 1974 through model year 1980. Scenarios
2 through 5 are based on three different assumptions about sulfate emissions.
1. No program to reduce the sulfur of unleaded gasoline,
no vehicular sulfate control, lead phase-down.
2. Blending and allocation program to reduce the
sulfur level of unleaded gasoline, modified lead
phase-down regulations, no vehicular sulfate
control.
3. A moderate blending and allocation program to keep the
sulfur levels of unleaded gasoline at one half of pool
levels, modified lead phase-down regulations, and a
moderate vehicular sulfate control program implemented
First cost over uncontrolled cars, fuel economy relative to 1974 cars
and sulfate emission rate are projected for each scenario. In the text
accompanying the graphs is an explanation of the types of systems used.
These systems were also shown in Table 1 in Section 2.
4.1 Suspend and Freeze @1.5HC, 15CO Without Catalysts
This scenario assumes sulfates are considered such a serious problem
that the industry removes catalysts from all. models starting in 1977 as
the result of some action taken by the government (e.g. repeal of
unleaded fuel regs, ban of catalysts, etc.). Starting in model year 1977
mostly advanced engine mod (EM-2) and some lean burn systems (LB-1) are
used to meet 1.5 HC, 15 CO Standards. Since the industry has not been
developing systems to meet these standards without catalysts the report
team projects that the fuel economy of the 1977 models under this scenario
will be about like their 1977 proto-type cars which have sufficiently
low feedgas to meet such standard. Average fuel economy is estimated
at 1.07 relative to 1974 which is a 7% loss from '75 or a 9% loss from
'76. Cost is reduced from the $200-$190 for 1975 1976 catalyst control
systems to $140.
Eventually, as lean-burn technology is developed and produced the fuel
economy under this scenario rises to 1.25, 25% better than '74 models,
11% better than '75 models. System cost is reduced to $50 by the elimination
of the EGR, air injection, etc. used on the EM-2 system.
Sulfate emissions under this scenario are a maximum of .025 gpm for the 1975
and 1976 models which use catalysts. 1977 and later models are below .005
gpm even with .03% by weight fuel sulfur. No programs to control fuel
sulfur or vehicle emissions are considered under this scenario since
sulfate levels are extremely low without such approachs.
-------
o
u
$400
$300
2 $200
•H
fe
$100
1.25
B
g 1.20
o
H
4)
I
00
1.10
1.05
1.00
.075
.050
.025
1974
3,28,3.1
First Cost
4.
1975 1976 1977 1978
1.5,15
1979
$400
$300
$200
$100
1.25
1.20
1.15
1.10
1.05
1.00
.075
,050
.025
1980
SCENARIO 1 --SUSPEND & FREEZE
-------
4.2 Suspend and Freeze at .9 HC, 9 CO
This is a minimum short term fuel economy loss scenario. 1975 California-
type emission control systems, oxidation catalysts with air injection
(OC-2) are used during the first effective year of the standard. Fuel
economy is estimated to be better than the fuel economy of the 1975
California cars, however, due to system improvements (better catalyst
technology, etc.) being available by 1977. Relative to 1974 the
economy is estimated to be 1.16. System cost is like 1975 California
system cost, about $250.
Beyond 1977 system cost continues to drop due to the phase-in of non-
catalytic, lean-burn technology and further optimization of the
oxidation catalyst sytem. By 1980 it is estimated that half of the market
will use LB-2, a lean-burn system with thermal aftertreatment, and half
of the market will use OC-1, catalyst, no air pump. The lean-burn cars
could reach a relative fuel economy level of 1.25 and the catalyst cars
could reach 1.20, the difference due to the use of leaded fuel and higher
compression ratio with the lean-burn cars. Cost of the lean burn system
is estimated at $90 and cost of OC-1 at $200 for an average cost of $140
in 1980.
Sulfates under this scenario depend heavily on the assumption about
regulations on fuel or vehicular sulfate emissions. Under the high
sulfur/no control assumption, sulfates are estimated to peak at .05
gpm in 1977. The phase-in of less expensive lean-burn and non-air injection
catalyst technology results in a reduction to .013 gpm, by 1980.
With unleaded fuel sulfur levels at half of pool levels and 50% sulfate
control from the levels of prototype 1977 cars implemented in 1978, the
sulfate level of the '77 models is .025 and the 1980 cars drop to below
.01.
A program to minimize fuel sulfur results in a sulfate emission rate below
.005 gpm starting with the 1976 models.
-------
$400
a $300
o
u
2 $200
$100
1.25
g 1.20
§ 1.15
(n
1.10
a)
1.05
1.00
8.
eo
.075 -
.050 -
.025 -
1974
3,28,3.1
First Cost
Fuel Economy
High Sulfur/No Vehicle Control
Moderate Blending/Some^Vehicle Control
Minimized Fuel Sul
$400
$300
$200
$100
1.25
1.20
1.15
1.10
1.05
1.00
.075
.050
.025
1975 1976
i.5,15,3.1
1977 1978 1979
.9,9
1980
SCENARIO 2 - SUSPEND & FREEZE @ .9,9
-------
4.3 Suspend for 1 yr. @ .9 HC, 9 CO. Hold .41 HC. 3.4 CO. 2.0 NOx for
1978 through 1980
This scenario gives the industry more time to work on the statutory
systems before they are forced to certify them in 1978. The 1977 cost
and economy levels are the same as for scenario 2, $250 and 1.16 relative
economy.
With the implementation of .41 HC, 3.4 CO, 2.0 NOX in 1978 cost increases
to $340 because of the use of start catalyst systems. Fuel economy
is estimated to drop by 5% from 197 to 1.10 relative to 1974.
Fuel economy is projected to improve annually thereafter until fully
optimized at 1.20 relative to 1974 by 1980. Cost continues to decrease
as the industry meres toward less expensive systems like lean-burn with
oxidation catalyst and advanced oxidation catalyst systems without
start catalysts. By 1980 average system costs are projected to be $230.
Sulfates under this scenario are similar hut somewhat higher than with
scenario 2 because catalysts are still needed on nearly all models
in 1980 to allow optimized fuel economy. With no control over fuel
sulfur or vehicles, sulfate emission hit .05 gpm in model year
1977 and stay there.
With 50% control on the vehicle (which m-ay only require reformulation
of the catalyst) and unleaded fuel at one half of pool sulfur levels
the peak sulfates would be .025 gpm in 1977 dropping to .13 by 1980.
Minimized fuel sulfur reduces sulfate to less than .005 gpm by 1976.
-------
$400
$300
to $200
$100
1.25
§ 1-20
u
W
« 1.15
b<
SI
2 1.10
(0
rH
01
K 1.05
1.00
I
oo
.075
2 .050
ai
-------
4.4 Denial with 2.0 NOy Held Through 1980
The technical appendix to the NOX decision and this years technical
appendix indicate that these levels are achievable by 1977. Average
first cost of systems to meet this level in 1977 is estimated at $300
increasing to $340 in '78 as efforts are made to maximize fuel economy.
Fuel economy is estimated to dip to 1.09 relative to 1974 cars in model
year 1977 but steady improvement to 1.20 in 1980 is projected thereafter.
Cost of the systems used is projected to drop after 1978 and reach the
same $230 level by 1980 as occured under scenario 3. A mix of lean-
burn systems with oxidation catalysts and advanced oxidation catalyst
systems is forseen.
The sulfates under this scenario are identical to scenario 3. Sulfates
would rise to .05 gpm in 1977 and stay there if no controls of vehicular
emissions or fuel sulfur levels are assumed. With a modest blending
and allocation program and 50% control of vehicular emissions a .025 gpm
sulfate peak in 1977 drops to .13 by 1980.
-------
$400
o $300
3
2 $200
$100
1.25
c 1.20
o
u
H
01
4)
a:
1.10
1.05
1.00
.075
8
«r -O5o
4J
a)
-------
4.5 Denial With a Push for Low NO
x
The basic assumption behind the development of this scenario was that the
maximum NOx control acheivable with the 1975 level of fuel economy would
be required. .41 HC, 3.4 CO, 2.0 NOx is required for 1977 and 1978. The
cost and fuel penalties for the 1977 model year are identical to those for
scenario 4 but no improvement in economy is realized in 1978 because the
industry is projected to "carry over" 1977 cars and direct their efforts
at developing dual catalyst systems for 1979 rather than concentrating on
improving the 1977 system for only one more year of production.
Cost rises to $450 over uncontrolled in 1979 when the dual catalyst system is
added and fuel economy drops to 1.09 relative to 1974 as more spark retard
is needed to reduce the increase in HC emissions caused by the use of the
dual cat system and higher EGR rates. By 1980 fuel economy is projected
to be improved to 1.15, about the 1975 model year level. Sulfates
under this scenario are identical to scenarios 3 and 4. Preliminary
tests, however, indicate a slightly lower sulfate conversion rate for
dual catalyst systems. This scenario would look a little better if
a non-methane HC standard was assumed as dual catalyst cars have
shown a high methane fraction in preliminary tests.
-------
a
o
u
$400
$300
£ $200
$100
1.25
o 1.20
o
w
4)
3 1.10
a
1.05
1.00
.075
i
.050
4J
-------
REFERENCES
1. "Automobile Emission Control-The Technical Status and Outlook as of
December 1974," prepared by Emission Control Technology Division,
Mobile Source Pollution Control Program, EPA, January 1975.
2. T.C. Austin and K.H. Hellman, "Fuel Economy of the 1975 Models,"
SAE paper 740970, October, 1974.
3. "Production of Low-Sulfur Gasoline," The M.W. Kellogg Co., EPA
Contract 68-02-1308, March 1974.
4. "Production of Low-Sulfur Gasoline in California Refineries," The
M.W. Kellogg Co., EPA Contract 68-02-1308.
5. "Potential for Motor Vehicle Fuel Economy Improvement,"
Report to the Congress by U.S. D.O.T. and U.S. EPA. October, 1974.
6. "Technology Panel Report for Potential for Motor Vehicle Fuel Economy
Improvement - Report to the Congress" Draft report by U.S. DOT
and U.S. EPA December 1, 1974.
7. Report by the Committee on Motor Vehicle Emissions, National Academy
of Sciences, November 1974.
8. R.C. Stempel and S.W. Martens, "Fuel Economy Trends and Catalytic
Devices," SAE paper 740594, August 1974.
9. J.J. Gumbleton, R.A. Bolton and H.W. Lang, "Optimizing Engine
Parameters with Exhaust Gas Recirculation," SAE paper 740104,
February 1974.
------- |