MEMORANDUM

DATE: June 27, 2005

SUBJECT: Emission Standards for Emergency Stationary CI Engines

FROM: Melanie Taylor, Alpha-Gamma Technologies, Inc.

TO: Sims Roy, EPA OAQPS ESD Combustion Group

The purpose of this memorandum is to provide the rationale used to
establish the emission standards for emergency engines, including fire
pump engines, in the proposed new source performance standards (NSPS)
for stationary compression ignition (CI) internal combustion engines
(ICE). An emergency stationary CI internal combustion engine is defined
in the proposed NSPS as a stationary internal combustion engine whose
operation is limited to emergency situations, maintenance checks, and
readiness testing. Examples include stationary ICE used to produce power
for critical networks or equipment (including power supplied to portions
of a facility) when electric power from the local utility is
interrupted, or stationary ICE used to pump water in the case of fire or
flood, etc. Examples also include stationary ICE used during Federal or
State declared disasters and emergencies, and simulations of emergencies
by Federal, State, or local governments.

**Emission Standards for Emergency Engines**

For engines with a displacement of less than 10 liters per cylinder, the
emission standards in the proposed NSPS are primarily based on the EPA
standards for nonroad diesel engines. The emission standards for engines
with a displacement between 10 and 30 liters per cylinder in the NSPS
are based on the EPA standards for marine diesel engines. The standards
for nonroad and marine diesel engines are phased in over several years
and have Tiers with increasing levels of stringency. Engines are
separated into engine power ranges, and some emission standards vary
between ranges. The basis for this is EPA's analysis of the
applicability of specific emission control strategies for each power
range of engines. The Tier 2 and Tier 3 standards for nonroad diesel
engines and the Tier 2 standards for marine engines are based on the
most advanced engine-based technologies available for the various
engines classes in the timeframe of the nonroad and marine diesel engine
rulemakings. For most nonroad diesel engines, the Tier 4 levels
represent the emission reductions possible from the application of
catalyzed diesel particulate filters (CDPF) and nitrogen oxides (NOx)
adsorbers to the expected emission levels for the previous tier engines.
The Tier 4 particulate matter (PM) standard for nonroad diesel engines
below 25 horsepower (HP) and the Tier 4 NOx standard for nonroad diesel
engines below 75 HP are not based on the application of add-on emission
control. Tier 4 standards for marine engines have not been promulgated
at this time. The EPA is currently reviewing the possibility of
promulgating more stringent standards for marine engines similar to the
Tier 4 standards promulgated for land based nonroad CI engines. In that
context, the EPA will review whether such technologies are appropriate
for stationary CI ICE with a displacement between 10 and 30 liters per
cylinder. The NSPS for such engines may, therefore, be revised at that
time to require more stringent standards in the future.

The EPA believes that it is appropriate to base the standards for most
stationary CI engines on the nonroad and marine diesel engine standards
because the design and emissions characteristics of the engines are very
similar. Engine manufacturers have indicated to EPA that in most cases
they do not separately design and manufacture separate CI engines for
stationary use, and they often sell the same CI engine for use in
nonroad and marine equipment as they do for use in stationary
applications. Most CI engines that are ultimately used in stationary
applications are designed and built for use in both stationary and
nonroad/marine applications. Engine manufacturers indicated that
stationary CI engines with a displacement of less than 10 liters per
cylinder were similar to nonroad diesel engines, and stationary CI
engines with a displacement of 10 liters per cylinder or more were
similar to marine diesel engines.

The EPA expects that even if there were no NSPS for stationary CI
engines, emissions from those engines would generally decline in step
with the decreasing emissions from nonroad and marine engines, since
many stationary engines are similar to nonroad and marine engines. The
EPA believes that this would be true until the Tier 4 standards that are
based on add-on control take effect; without the NSPS, engine
manufacturers would not equip stationary engines with add-on controls.
As part of the NSPS rulemaking process, the EPA evaluated the cost of
control per ton of pollutant reduced that would result from requiring
stationary engines to be equipped with add-on controls that would reduce
emissions to meet the Tier 4 emission standards. The cost per ton
analysis is presented in the memorandum entitled "Cost per Ton for NSPS
for Stationary CI ICE." In that memo, the cost per ton of CDPF and NOx
adsorber was evaluated for both emergency and prime (non-emergency)
engines. Prime engines are estimated to operate approximately 1,000
hours per year, while emergency engines operate an estimated 37 hours
per year. Because emergency stationary CI engines are only operated for
a few hours each year, emissions from these engines are relatively low
compared to emissions from prime engines. The cost of control per ton of
pollutant reduced is therefore much higher for emergency engines.

The EPA determined that the relatively high cost of control as compared
to the amount of pollutant reduced did not justify the selection of
add-on controls for emergency engines. The emission standards for
emergency engines are therefore based on the most stringent standards
that do not require add-on emission controls. The basis for the proposed
standards is as follows:

-   For emergency stationary CI engines with a displacement of less than
    10 liters per cylinder, the proposed standards are based on the Tier
    2 and 3 nonroad diesel engine standards, except that for emergency
    engines less than 25 HP, the proposed standards are based on the
    Tier 4 PM standard for nonroad diesel engines below 25 HP, and for
    emergency engines less than 75 HP, the proposed standards are based
    on the Tier 4 NOx standard for nonroad diesel engines below 75 HP.

-   For emergency stationary CI engines with a displacement of 10 liters
    per cylinder or more, the proposed standards are based on the Tier 2
    marine diesel engine standards.

**Fire Pump Engines**

Stationary CI fire pump engines are a subset of emergency engines. Fire
pump engines are emergency stationary CI engines certified to National
Fire Protection Association (NFPA) requirements that are used to provide
power to pump water for fire suppression or protection. During the NSPS
rulemaking process, EPA met with Clarke Fire Protection Products, a
leading provider of fire pump engines. Representatives from John Deere
and Moore Pump and Equipment also attended one of the meetings.

During the initial meeting with Clarke, EPA presented the potential
emission standards for emergency engines, which have been discussed
previously in this memorandum. The fire pump engine supplier stated that
engine manufacturers would not be able to produce fire pump engines that
could meet the Tier 2 emission standards in the timeframe proposed by
EPA. Also, according to Clarke, additional time is needed to meet the
Tier 3 levels, because engines must be designed, certified, and
manufactured to meet the specifications of NFPA 20 (Standard for the
Installation of Stationary Pumps for Fire Protection), which requires
the engine to be certified by independent certifying organizations such
as Underwriters Laboratory and Factory Mutual. This is a process that
takes approximately 3 years. Clarke also indicated that high speed
engines, which are engines with a rated speed of 2,560 revolutions per
minute or greater, would need even more time to comply with the Tier 3
standards.

According to Clarke, high speed engines allow the fire pump to produce
greater output water pressures, eliminating the need for a second pump.
Furthermore, Clarke indicated that many, if not all, of these high speed
engines are not replaceable with similar engines that meet EPA's
emission standards. Clarke indicated that it may be able to produce high
speed emergency fire pump engines that meet Tier 3 emission standards if
an additional 3 years are provided in addition to the extra 3 years
needed for emergency fire pump engines that are not high speed engines
to meet Tier 3 emission standards. In other words, high speed emergency
fire pump engines would be given up to 6 additional years to meet Tier 3
emission standards after the timeframe that other stationary CI engines
that are not fire pump engines would be required to meet Tier 3 levels.

Emergency fire pump engines account for a small percentage of all
stationary CI emergency engines. According to EPA estimates, emergency
fire pump engines represent about 3 percent of stationary CI emergency
engines. Resulting emissions by allowing certain emergency fire pump
engines to skip Tier 2 and providing additional time to comply with the
proposed Tier 3 emission standards are therefore minimal with respect to
the emissions from all stationary CI emergency engines. The EPA believes
it is appropriate to allow certain emergency fire pump engines to skip
Tier 2 and be given additional time to comply with the Tier 3 emission
standards of the proposed NSPS, as discussed above. For emergency fire
pump engines where there is no Tier 3 emission standard, i.e., engines
less than 50 HP and engines greater than 600 HP, EPA has provided
additional time to comply with the Tier 2 level. Stationary CI fire pump
engines are used in critical situations for life safety purposes and EPA
believes that the proposed allowances will ensure that the emergency
fire pump development process is not compromised and will provide
sufficient time to develop fire pumps that meet the requirements of NFPA
and EPA's proposed emission standards.