DieselNet UPDATE
May 2004
http://www.dieselnet.com/
US EPA adopts Tier 4 nonroad engine emission standards ----
The US Environmental Protection Agency (EPA) adopted its long expected
landmark diesel emission regulation--the final Tier 4 emission
standards and diesel fuel rule for new nonroad diesel engines. The new
standards, which were proposed in April 2003, mandate emission
reductions of particulate matter (PM) and oxides of nitrogen (NOx) on
the order of 90%. Tier 4 limits have been designed to force the use of
advanced emission aftertreatment devices (such as particulate filters
and NOx reduction catalysts) on new diesel engines in most power
categories. Various provisions of the new regulation become effective
from 2008 to 2015, with exact dates depending on the engine category.
Particulate filter-forcing PM limits come to power in 2011-13. Full
phase-in of NOx aftertreatment-forcing limits will be completed by
2014-15. The Tier 4 regulation also brings new HC emission limits. CO
standards are left unchanged at the Tier 2/3 levels.
The stringency and the "aftertreatment-forcing" character of the new
rule is consistent with the 2007/2010 standards for heavy-duty highway
engines and the Tier 2 emission standards for light-duty vehicles.
Nonroad engines--with emission standards more relaxed than those for
highway engines--have become a significant source of PM and NOx
emissions in the USA. According to EPA emission inventory models,
nonroad engines are responsible for 47% of the total PM emissions and
25% of NOx emissions from all mobile sources.
The Tier 4 emission standards apply to new mobile nonroad diesel
engines, such as those used in construction, agricultural, and
industrial equipment. The emission standards do not apply to
locomotive and marine engines, which are covered by separate EPA
regulations (but the new Tier 4 rule does regulate sulfur content in
locomotive and marine fuels). Exempted from Tier 4 standards are also
mining engines; mining engine emissions and air quality in mines
remain under the jurisdiction of Mine Safety and Health Administration
(MSHA).
An important part of the new rule is a low sulfur diesel fuel program,
which is implemented in order to enable the use of sulfur-sensitive
catalytic emission control technologies on nonroad engines. The fuel
program introduces the following sulfur limits:
- 500 ppm effective June 2007 for fuels used in nonroad,
locomotive and marine engines
- 15 ppm (ultra-low sulfur diesel) effective:
- June 2010 for nonroad fuel
- June 2012 for locomotive and marine fuels
The new sulfur limits in marine diesel do not apply to heavy oils (T90
> 700°F) used in large (Category 2 and Category 3) marine engines.
Exempted from the new fuel rule are also fuels used in stationary
diesels (including power generation), aircraft, industrial boilers, or
heating plants.
The maximum sulfur content in nonroad diesel fuels is currently not
regulated by the EPA. Nonroad fuels meet an industry specification of
0.5% (5,000 ppm) sulfur, with an average in-use content of about 3,000
ppm (for comparison, sulfur level in highway fuels, currently at 500
ppm, will be capped at 15 ppm from June 2006).
Tier 4 emission standards for PM and NOx and their phase-in periods
are listed in the following table. When a range of dates is given, the
PM standard applies from the beginning year, and the NOx limit is
fully phased-in by the last year.
Tier 4 Emission Standards, g/kWh (g/bhp-hr)
--------------------------------------------------------------------
Rated Power Year PM NOx
--------------------------------------------------------------------
< 19 kW (25 hp) 2008 0.40 (0.30) 7.5* (5.6)
19 - 56 kW (75 hp) 2013 0.03 (0.022) 4.7* (3.5)
56 - 130 kW (175 hp) 2012-2014 0.02 (0.015) 0.40 (0.30)
130 - 560 kW (750 hp) 2011-2014 0.02 (0.015) 0.40 (0.30)
> 560 kW (750 hp)
- generators 2011-2015 0.03 (0.022) 0.67 (0.50)
- all other 2011-2015 0.04 (0.03) 3.5 (2.6)
--------------------------------------------------------------------
* NOx + NMHC
The Tier 4 HC standard (for engines at or above 56 kW) is 0.19 g/kW
(0.14 g/bhp-hr). The rule also introduces an interim PM standard of
0.30 g/kWh (0.22 g/bhp-hr) for engines of 19-56 kW, effective 2008.
For comparison, the existing standards (engines of 75-130 kW) are PM =
0.30 g/kWh and NOx+NMHC = 4.0 g/kWh (Tier 3, 2007). To meet the Tier 4
limits in this engine category, PM emissions will have to be reduced
by 93% and NOx+NMHC by 85%.
With the exception of the smallest and the largest engines, the Tier 4
exhaust emission standards are similar in stringency to the 2007/2010
requirements for engines used in highway trucks and buses. The EPA has
designed the Tier 4 limits to force the transfer of advanced exhaust
gas aftertreatment technologies that are being developed for 2007/2010
highway engines to nonroad engines in the 2011-2014 timeframe. These
aftertreatment-forcing standards are:
- PM standards of 0.02-0.03 g/kWh, which are believed to require
the use of diesel particulate filters on all nonroad engines
above 19 kW (25 hp) from 2011-13
- NOx standard of 0.40 g/kWh, which is believed to require the use
of NOx reduction catalysts on engines of 56-560 kW (75-750 hp)
with full phase-in by 2014-15. NOx aftertreatment will be also
necessary on generator sets above 560 kW (NOx = 0.67 g/kWh). The
EPA believes that NOx adsorber-catalysts will be feasible by the
Tier 4 deadlines, but also mentions urea-SCR as the technology
suitable for large stationary engines.
Although most emission control technologies will be transferred from
highway engines, implementation of the Tier 4 standards may present a
bigger technological challenge. Among other factors, added complexity
is presented by the great diversity in nonroad engines--in 2002, there
were 650 nonroad engine families in the USA from some 60
manufacturers, compared to only 107 highway engine families from 10
manufacturers.
Tier 4 standards have to be met over the new nonroad transient cycle,
NRTC (most engines below 560 kW), as well as on the currently used ISO
8178 steady-state tests. Nonroad engines will also have to meet not-
to-exceed standards (NTE), which are measured without reference to any
specific test schedule. In most cases, the NTE limits are set at 1.25
times the regular standard for each pollutant.
The final Tier 4 rule does not require closed crankcase ventilation in
nonroad engines. However, in open crankcase engines, crankcase
emissions must be measured and added to exhaust emissions in assessing
compliance.
The EPA estimates that the average cost increase for 15 ppm S fuel
will be 7 cents per gallon. This figure would be reduced to 4 cents by
anticipated savings in maintenance costs due to low sulfur diesel. The
cost of Tier 4 engines is anticipated to increase by about 20%. For
most mobile equipment categories, the cost increase of Tier 4
compliant equipment is estimated at 1-3% as a fraction of total
equipment price. For example, for a 175 hp bulldozer that costs
approximately $230,000 it would cost up to $6,900 to add the advanced
emission controls and to design the bulldozer to accommodate the
modified engine.
It is not yet clear how well are the Tier 4 standards harmonized with
European regulations. In January 2003, the EU proposed its Stage
III/IV aftertreatment-forcing standards for nonroad engines, but the
final Directive has been delayed, in part due to standard
harmonization between EU and US authorities.
In a stark contrast to the 2007-2010 emissions/fuel rule for highway
engines, the Tier 4 rule has received almost exclusively positive
response and support from all stakeholders, including engine and fuel
industry, state and local air regulators, media, and environmental
organizations.
http://www.epa.gov/nonroad-diesel/
Selected stakeholders' response
API:
http://api-ec.api.org/media/index.cfm?objectid=58EDA536-1F54-43CF-B198
8F54EE021757&method=display_body
EMA: http://www.enginemanufacturers.org/admin/content/upload/159.pdf
DTF: http://www.dieselforum.org/statements/may_10_2004.html
Deere: http://www.newswire.ca/en/releases/archive/May2004/12/c2214.html
Cummins:
http://www.cummins.com/na/pages/en/mediaresources/pressreleases/affirm
s.cfm
DieselNet nonroad standards summary:
http://www.dieselnet.com/standards/us/offroad.html
---- US EPA drafting new locomotive and marine emission standards ----
The US EPA has issued an Advance Notice of Proposed Rulemaking (ANPRM)
which covers plans for future emission standards for locomotive and
marine diesel engines. The ANPRM was published together with the final
Tier 4 rule for nonroad diesel engines.
The EPA is considering more stringent standards for new and existing
locomotives, as well as for new marine diesel engines with per
cylinder displacement below 30 liters. The marine standards would
apply to diesel engines used in all applications: commercial
(excluding ocean vessels), recreational, and auxiliary. They would
also apply to engines at or below 37 kW, which were previously
included in the nonroad standards.
The emission standards would be modeled after the 2007-2010 highway
engine program and the Tier 4 nonroad rule, with an emphasis on
achieving large reductions in PM emissions through the use of advanced
emission control technology. These standards would be based on the
application of catalytic aftertreatment enabled by the availability of
ultra low sulfur diesel fuel. The Tier 4 diesel fuel program has set a
15 ppm sulfur limit for locomotive and marine diesel fuel beginning in
2012.
For locomotive engines, built as early as 2011, the EPA considers
establishing Tier 3 standards based on aftertreatment technologies for
both PM (particulate filters) and NOx (NOx adsorbers, urea-SCR)
emissions. Emissions for both pollutants would be reduced by about 90%
relative to the engine-out levels. The locomotive Tier 3 NOx
requirements would be phased-in within 3 years (i.e., by 2013).
A similar approach is considered for marine engines (with the
exception of the largest engines Category 3, over 30 liters per
cylinder--these will be subject to a separate regulation to be
developed by April 2007). The PM controls could be introduced starting
in 2011, with NOx standards phased-in over 3 years. Contrary to
locomotives, the marine standards would apply only to new engines.
Additional issues are present in Category 2 (5 - 30 liters per
cylinder) marine engines using residual fuels of high sulfur content
(not covered by the Tier 4 fuel rule). High sulfur bunker fuels may be
prohibitive for the use of such technologies as catalytic particulate
filters.
In addition to new engine standards, EPA is soliciting input on
voluntary provisions that could encourage cleaner engines and
retrofits, or accelerate replacement of existing engines.
Comments on the ANPRM will be accepted for 60 days from the date of
Federal Register publication. The EPA expects to publish a Notice of
Proposed Rulemaking for the rule by mid-2005 and a Final Rule by mid-
2006.
http://www.epa.gov/otaq/regs/nonroad/anprm.pdf
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