environmental facts
INNOVATIVE CARS
Each year more new automobiles come onto the road with
better emission control devices. But it takes about ten
years for a single model to be phased out. Thus, although
the 1975-1976 models will have the ultimate in control devices,
it won't be until the mid-1980's that nearly all cars on the
road are so equipped.
Yet the Clean Air Act requires stringent air quality
standards to be met throughout the Nation by mid-1977 at
the latest. While it is true that conventional internal
combustion engines (ICEs) are being equipped with new and
increasingly improved catalysts designed to hold down
emissions, that may not be enough to allow the national
ambient air quality standards to be met as soon as possible.
Throughout the Nation cars emit more than half of the
carbon monoxide, almost half of the hydrocarbons and about
two-thirds of all nitrogen oxides in the air. In congested
cities their contribution often is higher. Some 42 percent
of the American people live in metropolitan areas for which
transportation strategies must be developed to protect
human health.
As a consequence of this situation, EPA is searching
for cleaner alternatives to the car as we know it. New and
different power systems may enable us to lower emissions
enough to protect both public health and environmental
quality. In this regard, EPA is watching the development
of six engines as a potential cure for automotive air
pol1ution.
The Diesel Engine
The diesel engine has been tested successfully in EPA
laboratories and meets stringent Federal emission limits
on carbon monoxide (CO) and hydrocarbons (HC). It also
gets 75 percent better fuel economy than a conventional
ICE of the same weight. If it were mass produced, in a
decade it could save Americans an estimated $90 billion.
But several bugs remain. Among them: refinery conversion,
particulate emissions, nitrogen oxide emissions (NOx),
odor, noise and driveabi1ity. Daimler-Benz markets a
diesel car in the United States.
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY • WASHINGTON, D.C. 20460
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The Stratified Charge Engine
One version of the stratified charge engine has been
tested after 50,000 miles by EPA with lower CO and HC emissions
than any other gasoline-fueled engine without after-treatment
devices. Honda Motor Company developed the four-cylinder
engine for use in the smaller compacts, but it has not yet
been imported into the United States. The low-emission
features of the engine result from separating the combustion
process in each cylinder into two chambers. The smaller
"prechamber" is supplied with a rich fuel-air mixture, and the
larger, main chamber is supplied with a very lean mixture.
Overall, the fuel-air mixture is much leaner than that used
by an ICE throughout its combustion process. The Ford Motor
Company has purchased nonexclusive worldwide rights to
develop, build and sell the Honda engine. If it can be
perfected in mass production, it could meet Federal emission
limits more cheaply than catalytic converters. This version
of the stratified charge engine is being scaled up now to
fit larger, heavier cars. So far, it performs well and uses
fuel conservatively; over a ten-year period it could save
Americans $9 billion.
The Rotary Engine
A Mazda rotary engine manufactured by Toyo Kogyo of
Japan has met Federal CO and HC standards after 50,000 miles.
No loss of fuel economy occurred in achieving the standards
although, in general, rotaries show as much as a 35 percent
loss in fuel economy over ICEs. In spite of this characteristic,
rotary engines appear to be selling well. The engine that
met CO and HC standards was not equipped with a device to con-
trol NOx. However, well-known techniques such as exhaust gas
recirculation or modified carburetion can be applied to
lower NOx emissions. General Motors Corporation (GM)
plans to market a Wankel rotary engine in the Chevrolet
Vega during 1974. GM is already planning at least one further
model designed and built around the engine. GM's president
has stated, "The full potential of the rotary can only be
achieved when the total vehicle is designed and built around
it... Ultimately we intend to take full advantage of these
opportunities and have a unique and highly desirable product."
GM is also discussing possible future sale of rotary engines
to American Motors Corporation.
The Gas Turbine Engine
The gas turbine is potentially reliable and quiet. EPA
and the National Aeronautics and Space Administration (NASA)
are working to develop the technology needed for a low-pollution
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automobile using a gas turbine engine. NASA was asked to
help because of its experience ir, related propulsion and
power technologies. Unlike the ICE in which combustion
takes place in individual cylinders, the gas turbine uses
a single combustion chamber and combustion is continuous.
Power is generated when heat expands gases from the combustor
to drive a high-speed turbine. Power from the moving turbine
is then transmitted through a set of gears to the car's trans-
mission. Under the agencies' agreement, NASA's Lewis
Research Center in Cleveland will assist EPA's Alternative
Automotive Power Systems Division in Ann Arbor, Mich. Lewis'
role will be to direct a number of technology development
contracts for EPA, conduct in-house research and evaluate
key components of an automotive gas turbine. Current EPA
contracts to be managed by Lewis total $1.2 million. The
main focus of the work will be on combustion chambers which
would appreciably reduce the amount of pollutants produced
in the combustion process and improving the efficiency of
both compressor and turbines in order to boost gas mileage
and improve driveability. EPA has also awarded a $6.4
million contract to Chrysler Corporation for research and
development to resolve technical problems that now block
the introduction of gas turbine engines that could meet the
1976 emission standards. The goal of the contract is to
determine whether the gas-turbine-powered automobile can be
made competitive with ICEs in fuel economy, performance
reliability and potential mass production cost.
The Steam Engine
The steam engine is still a long-term possibility.
Four firms under contract to EPA are developing versions
of this Rankine cycle engine in competition for another
EPA contract to develop a prototype car. In a Rankine
cycle power system, combustion takes place outside the
engine. The hot exhaust gases heat a fluid such as water
which then expands in either a turbine or a piston-type
expander to create power. Until recently, some 40 years had
passed without a single significant technological advance in
the Rankine cycle system. The four contractors and their
engine versions are : Lear Motors Corporation, Leareno,
Nev., water vapor turbine; Steam Engine Systems Company,
Watertown, Mass., water vapor reciprocating expander; Thermo
Electron Corporation, Waltham, Mass., organic fluid recipro-
cating expander; and Aerojet Liquid Rocket Company, Sacra-
mento, Calif., organic fluid turbine.
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The Electric Engine
The electric engine may suit special urban services
in the coming years. Under the Clean Air Act, the Federal
Government will pay premium prices for motor vehicles whose
emission control performance is significantly better than
Federal standards required for conventional cars. Four types
of battery-powered vehicles manufactured by the Battronic
Truck Corporation, Boyertown, Pa., have been designated
"low-emission vehicles" by EPA. The vehicles must now be
judged by a Low Emission Vehicle Certification Board to
determine if they are a suitable substitute for any class
of vehicles Currently being purchased by the Federal Gov-
ernment. If the electric vehicles are certified as suitable,
they may be purchased by the Federal Government for one and
a half times the price of the conventional transportation
they replace. The Board may raise the purchase premium to
twice the conventional price by designating the vehicles
"inherently" low polluting. In such vehicles, emission
control must be inherent in the engine design and not the
result of add-on equipment. EPA has recommended that this
designation be given. In making the low-emission vehicle
determination, EPA considered only the emissions from the
vehicles themselves. The Clean Air Act does not authorize
considering pollutant emissions from electricity generating
plants which provide power for the vehicles' batteries. The
Battronic vehicles include a merchandise van capable of
carrying 2500 Ibs. of cargo, a suburban bus carrying one
driver and 11 passengers, a transit bus carrying one driver,
15 passengers and 10 standees, and a bakery van carrying
3200 Ibs. of cargo.
September 1973
FS '- Mobile 1
•& U.S. GOVERNMENT PRINTING OFFICE 1973-733-410/2 3-1
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