v>EPA
United States
Environmental Protection
Agency
Air and Radiation
EPA420-F-96-009
July 1996
Office of Mobile Sources
Environmental
Fact Sheet
Control of Emissions From
Nonroad Engines
In response to environmental and public health concerns, the
U.S. Environmental Protection Agency (EPA) is establishing
emission standards for a number ofnonroad engine
categories. EPA's first standards for diesel-fueled nonroad
engines greater than 50 horsepower began to take effect in
1996. These engines are typically used in farm, construction,
material handling and logging equipment. Over the past year,
EPA has been working with the California Air Resources
Board (CARB) and nonroad engine and equipment manufac-
turers to agree upon a "Statement of Principles" (SOP) that
would propose future standards for this category of diesel-
fueled nonroad engines as well as for the currently uncon-
trolled gasoline- and propane-fueled nonroad engines above
25 horsepower used in similar applications.
History of
Nonroad
Controls
Emissions from engines used in nonroad equipment are a significant
source of oxides of nitrogen (NOx), volatile organic compound
(VOC) and particulate matter (PM) emissions. Emissions from
nonroad engines can be particularly troublesome as nonroad
equipment often operates in urban areas, potentially exposing large
numbers of people to harmful pollutants. In some areas of the
country, emissions from nonroad engines represent a third of the
total mobile source NOx and VOC inventory and over two-thirds of
the mobile source PM inventory.
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The 1990 Clean Air Act Amendments specifically directed EPA to
study the contribution of nonroad engines to urban air pollution, and
regulate them if warranted. In 1991, EPA released a study that
documented higher than expected emission levels across a broad
spectrum of nonroad engines and equipment. In response, EPA
initiated several regulatory programs for nonroad engines. One of
these programs set emission standards for diesel-fueled nonroad
engines greater than 50 horsepower, which is being phased in from
1996 to 2000. Under these standards, EPA projects that NOx
emissions from new diesel-fueled nonroad equipment will be
reduced by 37 percent.
Tighter
National
Emission
Standards
EPA and CARB have been meeting with nonroad engine and
equipment manufacturers over the last year to develop a nonroad
SOP that will propose tighter emission standards and other
provisions for nonroad engines manufactured after 2000. For the
purposes of this SOP, "nonroad" primarily refers to applications such
as farm, construction, material handling, and logging equipment.
EPA and CARB hope to reach agreement on the nonroad SOP
during the summer of 1996. EPA expects to issue a Notice of
Proposed Rulemaking (NPRM) to formally propose the new
emission standards contained in the nonroad SOP in early 1997. EPA
expects that the NPRM will cover all sizes of diesel-fueled nonroad
engines, and those gasoline-fueled and propane-fueled nonroad
engines above 25 horsepower. (Other nonroad applications, such as
recreational boats, locomotives, and smaller gasoline-fueled nonroad
equipment, are being addressed in separate EPA initiatives.)
Nonroad
Engine
Technology
Many nonroad engines are diesel-fueled compression-ignition
engines. Diesel engine technology has continually improved over the
past twenty-five years, resulting in increasingly fuel efficient,
reliable and durable engines. Controlling NOx and PM emissions
presents a special challenge for the diesel engine industry, however.
The high cylinder temperature typical of diesel combustion causes
nitrogen and oxygen from the intake air to combine as NOx. Due to
the unique fuel and combustion chemistry of diesel engines, PM
emissions are also inherently higher than emissions from comparable
gasoline engines. Control technologies that reduce NOx may
increase PM, adding to the technological challenge.
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Because many engines used in highway trucks are similar to those
used in nonroad equipment, it is likely that highway diesel engine
control technologies will be transferred to nonroad applications to
comply with tight standards. However, many of the emission control
strategies currently used in highway diesel engines may require
further development for nonroad applications because nonroad
equipment has different operating characteristics and chassis
restrictions than do the highway counterparts. For example, highway
engines can utilize the cooling properties of high vehicle speed, an
advantage not available for nonroad equipment. Additionally,
nonroad engines are often made for a wide range of applications so
engine and chassis design changes are not as readily integrated,
resulting in added complications.
For nonroad gasoline-fueled and propane-fueled engines, it is
expected that emission control technologies that are well-established
in the automotive industry, such as exhaust gas recirculation, closed-
loop fuel control, and catalytic converters, may find application.
For More
Information
For more information on this program, please call the NOx/PM
Initiative voice mailbox at (313) 741-7887, or write to:
U.S. Environmental Protection Agency
National Vehicle and Fuel Emissions Laboratory
NOx/PM Initiative - Nonroad Team
Engine Programs and Compliance Division
2565 Plymouth Road
Ann Arbor, Michigan 48105
The Office of Mobile Sources also has information available on the
EPA Internet server and via dial-up modem on the Technology
Transfer Network (TTN), an electronic bulletin board system (BBS).
World Wide Web: http://www.epa.gov/OMSWWW
TTN BBS: 919-541-5742 (1200-14400 bps, no parity, 8 data
bits, 1 stop bit); voice helpline: 919-541-5384
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