United States Air and Radiation EPA420-F-02-034
Environmental Protection September 2002
Agency
Office of Transportation and Air Quality
&EPA Technical
Highlights
Emission Regulations for
Stationary and Mobile Engines
The U. S. Environmental Protection Agency (EPA) has adopted
emission standards for various types of nonroad engines. As directed
by Congress in the Clean Air Act, these emission standards do not
apply to stationary engines. This fact sheet is addressed to owners of
stationary engines to answer several questions about how we
implement these requirements.
Why does it matter whether an engine is "stationary"
or "mobile"?
Congress has directed EPA to set emission standards for new nonroad
engines and prevented state and local governments from adopting any
standards for these engines, with certain exceptions. At the same time,
Congress reserved the right of state and local governments to regulate
emissions from stationary engines. As a result, we went through a
public rulemaking to establish clearly which engines are nonroad (mo-
bile) engines and which are stationary engines.
What are examples of nonroad and stationary
engines?
Stationary engines are used in many applications where they can be
installed in a fixed location, such as power generators or irrigation
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pumps. Nonroad (mobile) applications include these same types of
equipment if they are made to be portable (or transportable). For ex-
ample, a generator mounted on a pallet or a trailer would generally not be
considered stationary. Nonroad engine applications also include many
kinds of vehicles that are clearly not stationary, such as tractors, loaders,
forklifts, locomotives, and many kinds of marine vessels.
So, what exactly is a stationary engine?
Stationary engines include all internal-combustion engines that are used
either in a fixed application, or in a portable (or transportable) applica-
tion in which the engine will stay at a single site for at least a full year.
Engine and equipment manufacturers need to determine before the
engine is placed in service whether their customers will use the engine in
a mobile or stationary application. This way, engine manufacturers will
appropriately build an engine (and certify it if necessary) before it
reaches its final installation. Similarly, nonroad equipment manufactur-
ers must install only certified nonroad engines in nonroad equipment.
For example, a trailer-mounted generator would be considered stationary
only if the equipment and engine manufacturers had clear information
showing that, throughout the engine's life, the owner would operate the
engine at single locations for at least 12 months.
What about engines that operate only at summer
construction projects?
We are aware that some work sites, such as summer construction
projects, operate for less than a full year. For engines at these seasonal
work sites, we apply a different test to determine if they qualify as
stationary engines. For a work site to qualify for having any stationary
engines, it must be in operation for at least two consecutive years with a
"work season" of at least three months. We would consider individual
engines at such a work site to be stationary if they operate as stationary
engines for a full season.
What emission standards apply to nonroad (mobile)
engines?
We have adopted emission standards for almost all nonroad engines.
These emission standards are generally tailored to the specific applica-
tion and type of engine. For example, we have separate emission stan-
dards for marine engines, locomotives, and other land-based diesel
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engines (see Table 1). We also usually have separate standards for
diesel- and gasoline-fueled engines. These standards typically apply to
engine manufacturers, who certify with us that their new engines will
meet emission standards over an established period of operation with
proper maintenance and use. EPA's nonroad emission standards gener-
ally do not affect any engines that have already been placed into service,
unless they are installed in new equipment or used in a different applica-
tion (such as converting a locomotive engine to power a generator or a
vessel)1.
In addition, California may adopt (and has adopted) standards for most
nonroad engines, which other states may copy. State and local authori-
ties may also regulate the use and operation of nonroad engines.
What emission standards apply to stationary
engines?
EPA may adopt New Source Performance Standards (NSPS) or National
Emission Standards for Hazardous Air Pollutants (NESHAP) for station-
ary engines. We have not yet done so, but are expecting to propose
NESHAPs for stationary engines in 2002.
In addition, state and local agencies may adopt requirements for station-
ary engines. These requirements are usually designed to help areas meet
ambient air quality standards under federally mandated State Implemen-
tation Plans (SIPS), though states may also adopt requirements for other
air quality purposes. In any case, these requirements typically take the
form of a permit process in which you show that your engines use a
certain type of technology or operate at a certain emission level. Manu-
facturers typically take the responsibility of showing that their engines
meet these requirements, but you may have a significant responsibility
to ensure proper operation and maintenance.
Especially in rural counties, it may be that no state or local emission
standards apply. In other areas, local authorities may simply require that
engines meet EPA emission standards that apply to comparable nonroad
engines. In areas with the most need to address air quality problems,
local requirements may call for emission controls that are more chal-
1 EPA's locomotive regulations apply to certain older locomotive engines
when those engines are rebuilt.
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lenging than EPA standards. See www.cleanairworld.org/ for links to
many state and local offices that would implement requirements for
stationary engines.
What happens if someone moves a stationary
engine?
If you have a stationary engine that is not certified to EPA emission
standards, you must use it consistently with our definition of stationary
engines. Converting it to a mobile engine would require engine certifi-
cation to applicable standards for nonroad engines. Anyone who moves
a stationary engine or installs it in a mobile application may be consid-
ered a manufacturer of new nonroad equipment and risks substantial
fines if the engine is not certified.
If you need to replace a stationary engine that fails prematurely, this
restriction on moving the failed engine does not apply. You may replace
it without recalculating the residence time described above.
May I use an EPA-certified nonroad engine in
stationary applications where there are no local
requirements?
Yes. Many engine manufacturers choose to do this to avoid the com-
plexity of offering multiple engine models and to reduce the risk of
someone using an uncertified engine in a mobile application.
Can I convert a used mobile engine to provide power
as a stationary engine?
This depends on local requirements. State or local authorities may
choose to apply emission-control requirements to these engines.
How does Customs treat imported stationary
engines?
The U.S. Customs Service works with us to enforce our requirements. If
anyone tries to import an uncertified engine without clear evidence that
it will be used in a stationary application, Customs may impound the
engine temporarily or refuse entry, depending on the circumstances. We
therefore recommend that all imported stationary engines have a perma-
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nent label identifying them as stationary engines that are not subject to
EPA's emission standards for nonroad engines. See EPA's declaration
form for more information about importing stationary engines at:
www.epa.gov/otaq/imports/forms/3520-21 .pdf.
Table 1
Current Emission-Control Programs
Engine Category
Location in the
Code of Federal Regulations
Land-based nonroad diesel
engines
40 CFR part 89
Lawn and garden engines
(and other spark-ignition
engines under 19 kW)
40 CFR part 90
Marine spark-ignition engines
40 CFR part 91
Marine diesel engines
40 CFR part 94
Locomotives
40 CFR part 92
Industrial spark-ignition
engines (and other land-
based engines over 19 kW)
40 CFR part 1048
Recreational vehicles
40 CFR part 1051
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Where Can I Get More Information?
Additional documents on nonroad engine emission standards are avail-
able electronically on the Web site for the Office of Transportation and
Air Quality at:
www.epa.gov/otaq/nonroad.htm
Additional information related to EPA regulation of stationary engines is
available electronically on the Web site for the Office of Air Quality
Planning and Standards at:
www.epa.gov/ttn/atw/rice/ricepg.html
Document information is also available by contacting:
Nonroad Engines
ASD Information Line
Phone:(734)214-4636
E-mail: asdinfo@epa.gov
Stationary Engines
Sims Roy
919-541-5263
E-mail: roy.sims@epa.gov
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