United States Air and Radiation EPA420-F-97-045
Environmental Protection December 1997
Agency
Office of Mobile Sources
&EPA Regulatory
Announcement
Proposed Phase 2 Standards for
Small Spark-Ignition Engines
The U.S. Environmental Protection Agency (EPA) is proposing Phase 2
standards for nonroad small spark ignition (SI) engines that will reduce
hydrocarbons plus oxides of nitrogen (HC+NOx) by an additional 30
percent beyond the current Phase 1 standards. The proposed rule
includes provisions that give industry flexibility and ease the transition
to the more stringent Phase 2 program, especially for small volume
engine and equipment manufacturers. The new standards would be
phased in between 2001 and 2005.
History of Rulemaking
In July 1995, EPA finalized the first federal regulations affecting small
nonroad SI engines at or below 19 kilowatts (kW), or 25 horsepower.
The regulations, commonly known as "Phase 1," took effect for most
new handheld and nonhandheld engines beginning in model year 1997
and are expected to result in a 32 percent reduction in HC emissions
from these engines. Handheld engines are used in equipment such as
chain saws, string trimmers and leaf blowers. Examples of equipment
using nonhandheld engines include lawn mowers, garden tractors, tillers
and certain construction equipment.
I Printed on Recycled Paper
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Table 1: Small SI Engine Classes
Nonhandheld
Class I
<225 cc
Class II
>225 cc
Handheld
Class III
<20 cc
Class IV
20 cc 50cc
This "Phase 2" proposed rule follows several years of negotiations
between EPA, engine manufacturers and environmental groups. The
proposal is based closely on two Statements of Principles (SOPs) signed
by EPA and industry groups. EPA published an Advance Notice of
Proposed Rulemaking in March 1997 which announced the signing of
the two SOPs and requested comments on all aspects of the SOPs for
purposes of developing the proposed rule. As a result of a suit by the
Sierra Club, EPA is under a court-ordered deadline to complete a final
Phase 2 rule for these engines by December 23, 1998.
While EPA's and California's Phase 1 standards for these engines were
essentially the same, California (because of its unique air quality prob-
lems) is pursuing a second phase of standards that would be substantially
tighter than EPA's.
Overview of Proposed Rule
The proposed Phase 2 program is expected to result in a shift to cleaner,
more durable engine technology. Notably, the Phase 2 program will lead
to increased use of automotive-style overhead valve (OHV) technology
in nonhandheld engines. In addition, the proposal includes new program-
matic requirements to ensure that engines meet the tighter standards
throughout the useful life of the equipment. Highlights of the proposed
rule include:
• Tighter emission standards for HC+NOx (in grams per kilowatt-
hour (g/kW-hr)) to be phased-in during model years 2001 through 2005.
Table 2: Phase 2 HC+NOx Emission Standards for Nonhandheld Engines
(in g/kW-hr)
Engine
Class
Class 1
Class II
Model
Year 2001
25.0
18.0
Model
Year 2002
25.0
16.6
Model
Year 2003
25.0
15.0
Model
Year 2004
25.0
13.6
Model
Year 2005
25.0
12.1
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Table 3: Phase 2 HC+NOx Emission Standards for Handheld Engines
(in g/kW-hr) Showing Phase-in by Percentage of Production
Engine
Class
Class III
Class IV
Class V
HC+NOx
Emission
Standard
210
172
116
Model
Year 2002
20%
Model
Year 2003
40%
Model
Year 2004
70%
Model
Year 2005
100%
(When compared to Phase 1 standards, Phase 2 standards may not appear
more stringent in all cases. This is because Phase 1 standards are 'new
engine 'standards and Phase 2 standards are in-use standards)
Three useful life categories for nonhandheld engines and two useful
life categories for handheld engines to account for widely varying
product lives.
Table 4: Useful Life Categories
for Nonhandheld Engines (hours)
Class 1
Class II
Category C
66
250
Category B
250
500
Category A
500
1000
Table 5: Useful Life Categories for Handheld Engines (hours)
Class III, IV and V
Residential
50
Commercial
300
A compliance program to ensure engines continue meeting the stan-
dards for the useful life of the engine, including certification, produc-
tion line testing, and in-use testing.
Health and Environmental Benefits
EPA's principle reason for controlling emissions from small SI engines is
the role of their HC emissions in forming ozone, a primary component
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EPA's principle
reason for con-
trolling emis-
sions from small
SI engines is the
role of their HC
emissions in
forming ozone, a
primary compo-
nent of smog.
of smog. The Phase 2 standards should result in a 30 percent reduction in
HC+NOx emissions from these engines beyond the 32 percent reduction
expected from the Phase 1 standards. This is equivalent to an annual
reduction of 135,000 tons of HC+NOx emissions by the time a complete
fleet turnover occurs in 2025. This reduction in HC+NOx emissions will
be accompanied by an estimated overall reduction in fuel consumption
of about 9 percent.
Small SI engines produce approximately one tenth of U.S. mobile source
HC emissions and are the largest single contributor to nonroad HC
inventories. Thus, the proposed Phase 2 standards would help the States
in their progress towards compliance with the National Ambient Air
Quality Standards for ozone.
The proposed standards will generate significant reductions in emissions
from these engines at very low costs. Further, they will result in fuel
economy improvements which will offset much of the costs of the
emission reductions.
Effect On Industry
The proposed regulation will require engine manufacturers to:
• build cleaner, more durable engines;
• certify that those engines will meet standards for their full regulatory
useful lives; and
• conduct testing of in-use engines to prove their performance in-use.
The Phase 2 standards will drive virtually all larger (Class 2)
nonhandheld engines to the use of OHV technology. This will improve
the emission durability and fuel economy of these engines. (A trend
toward overhead valves is already underway for these engines.) For
other categories of engines, the standards will require improvements to
existing engine design, but will not require major technological changes.
The rule will not require the use of catalysts for any group of engines.
The proposed rule includes provisions to ease the transition from Phase 1
to the Phase 2 program, to ensure that the Phase 2 standards are cost-
effective and achievable, and to minimize the compliance burden while
maintaining the environmental benefits of the rule. These provisions
include phase-in schedules, a certification averaging, banking, and
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trading program for nonhandheld engines, special compliance provisions
for very low emitting engines, and special provisions to ease and/or
delay the impact of the rule on low volume engines and equipment.
The cost of meeting the tighter standards are expected to range from less
than a dollar per engine for smaller, lower priced engines, to approxi-
mately $18 for larger, more expensive engines. When fuel savings are
considered, costs are lower and a net savings may actually result for
some larger nonhandheld engines.
Public Participation Opportunities
EPA desires full public participation in arriving at final rulemaking
decisions. The Agency solicits comments on all aspects of the proposal
from all interested parties. Wherever applicable, full supporting data and
detailed analysis should also be submitted to allow EPA to make maxi-
mum use of the comments. Commenters are especially encouraged to
provide specific suggestions for changes to any aspects of the proposal
that they believe need to be modified or improved. A public hearing will
also be held on February 11, 1998 beginning at 10:00am in Ypsilanti,
Michigan. For additional information on the public hearing, please call
(734) 668-4334.
For instructions on submitting written comments, please see the Federal
Register notice published on January 27, 1998. It is available from the
EPA Air and Radiation Docket by calling 202-260-7548; please refer to
Docket No. A-96-55. In addition, the proposed rule is available electroni-
cally via the EPA Internet server at:
http://www.epa.gov/OMSWWW/equip-ld.htm
For More Information
Additional documents on small nonroad SI engines are available electronically at
the Internet site given above, or by contacting Russ Banush at:
U.S. Environmental Protection Agency
Office of Mobile Sources
2565 Plymouth Road
Ann Arbor, MI 48105
734-668-4333
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