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SUMMARY AND CONCLUSTONS
In legislating the Clean Air Amendments of 1970, the Congress
asked the Environmental Protection Agency (EPA) to contract with the
National Academy of Sciences (NAB) to conduct a comprehensive study
and investigation of the technological feasibility of meeting the
motor vehicle emissions standards prescribed in accordance with the
law. In responding to this request, pursuant to a contract with the
EPA, the Academy established a Committee on Motor Vehicle Emissions
(CMVE) and charged it with the conduct of this study.
In its investigation of "technological feasibility," the CMVE
addres sed the following is sues:
1. Determination of the feasibility of developing
and designing an emissions control system that
would enable compliance with the legally estab-
lished emissions standards as judged by the
certification procedures prescribed by the EPA.
2. The feasibility of mass producing those systems
of promising design.
3. The projected performance of such emissions
control systems in customer usage, including
the requirements for maintenance necessary
to assure continuing reliability.
4. The costs, per vehicle, associated with acqui-
sition, maintenance, and operation of the
emissions control system.
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In the course of its work, the Committee has examined the
variety of approaches of manufacturers and others to the problems
relating to emissions control. At the time of this report, progress
toward resolution of these problems in the four aspects listed above,
although rapid, is uneven and uncertain, and the outlook toward 1975
and 1976 is not yet clear. Moreover, the rapid pace of that progress
complicates judgment concerning the most appropriate course of action
for attainment of the standards required by the law.
For 1975 model year light-duty motor vehicles, the Committee
concludes that --
1. Four types of systems will meet the prescribed
emissions standards during certification testing.
These are: the modified conventional engine
equipped with an oxidation catalyst, the car-
bureted stratified-charge engine, the Wankel
engine equipped with an exhaust thermal reactor,
and the diesel engine. For the catalyst system,
one catalyst change must be permitted during the
SO,OOO mile durability testing for certification,
and fuel with a suitably low level of catalyst
poisons must be allowed. In determining whether
vehicles mass-produced comply with an outstanding
certificate of conformity under Section 206 of the
Clean Air Act, provisions must be made for averaging
of emission test results within a vehicle and engine
class.
2. Vehicles incorporating these systems can be mass-
produced in great enough volume to satisfy, in
aggregate, the expected demand for vehicles in
model year 1975.
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3. It is important for two reasons that a suitable
maintenance and inspection system be established
for vehicles in use by the public.
First, there are no data concerning the
deterioration of emission-control systems under
conditions of customer use, and the Committee
believes that the certification procedure alone
is not a sufficient indicator of system durability.
Even if it is demonstrated that properly maintained
vehicles can comply with the standards under condi-
tions of customer use, an adequate vehicle mninten-
ance and inspection system will be required to assure
that most vehicles will meet the standards when used
by the general public; this is especially important
for catalyst-equipped vehicles.
Second, if it is determined that a substantial
number of any class of vehicles or engines, although
properly maintained and used, is not meeting the stan-
dards in use, Section 207(c) of the Clean Air Amedments
empowers the Administrator of EPA to require the manu-
facturer to submit a plan for remedying the nonconformity.
Under such a plan, the manufacturer is required to correct
only those vehicles or engines which have been properly
maintained and used.
4.
The average increase in sticker price due to the emiss~ons-
control system of a catalyst-equipped vehicle is esti-
mated to be $160 above a current (1973) vehicle and $230
above a 1970 model year vehicle. Except for the diesel
engine, lesser increases are expected for the other
emission-control systems, when comparing vehicles of
similar size and type.
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Model year 1975 vehicles using Wankel engines or
catalyst-equipped spark-ignition piston engines will use
significantly more fuel than their 1973 counterparts.
Carbureted stratified-charge engines will suffer only
a slight fuel penalty; and the diesel engine will offer
improved fuel economy, enough to compensate for its high
initial cost within a few years of driving.
For 1976 model year light-duty motor vehicles, the Committee
concludes that --
1.
Five control systems now in early stages of development
have met the 1976 "mission standards at low mileage.
These are: the modified conventional engine equipped
with dual catalysts, or with dual catalysts plus thermal
reactor, or with two thermal reactors and a reduction
catalyst, or with a three-way catalyst and electronic
fuel injection, and the stratified-charge engine employing
fuel injection and equipped with an oxidation catalyst.
It is possible, but not certain, that some of these sys-
tems may prove to be certifiable for 1976, contingent upon
the acceptance of the same provisos previously mentioned
for 1975 model year vehicles.
More importantly, the recently developed carbureted
stratified-charge engine, after 50,000 miles of durability
testing on a compact car, has achieved well over the 90
percent reduction in hydrocarbon and carbon monoxide emis-
sions called for in the Act and about 83 percent reduction
in NOx. The Committee believes that this engine will be
certifiable for 1976, at least in smaller engine sizes.
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in'
2. If certifiable, vehicles incorporating any of these
systems can be mass-produced, but not necessarily
in great enough volume to satisfy, in aggregate, the
expected demand for vehicles in model year 1976.
3. The Committee holds the same concerns for performance
of 1976 vehicles in use as discussed above for 1975
systems.
The average increase in sticker price of a dual-
catalyst-equipped vehicle is expected to be $290
above a current (1973) vehicle, and $370 above a
1970 model year vehicle. Average annual costs of
a dual-catalyst em~ssions-control system, including
maintenance and fuel, with the increase in sticker
price amortized over five years, is estimated to
be $260 per year, compared with a 1970 model year
vehicle. In contrast, the annualized costs for
several other systems are estimated to be less than
$100.
The Committee is greatly concerned about the trend of
development of the 1976 control systems. The system most likely
to be available in 1976 in the greatest numbers - the dual-catalyst
system - is the most disadvantageous with respect to first cost,
fuel economy, maintainability, and durability. On the other hand,
the most premising system - the carbureted stratified-charge engine -
which may not be available in very large numbers in 1976, is superior
in all these categories. The Committee wishes to alert both EPA
and the Congress to this development and believes that it warrants
immediate attention.
Representative terms from entire chapter:
engine equipped