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December 4, 2008

Mr. Jaime Pagan

Energy Strategies Group

US Environmental Protection Agency

D243-01

Research Triangle Park, NC 27711

RE: Resolution of Outstanding Issues in 40 CFR 60 Subpart IIII, Standards of 

Performance for Stationary Compression Ignition Internal Combustion Engines, as 

Applied to Larger CI engines. 

Dear Mr. Pagan:

The Engine Manufacturers Association (EMA) represents the major manufacturers of 

internal combustion engines used in stationary sources that are now regulated by the recently 

promulgated Compression Ignition (CI) NSPS (40 CFR 60 Subpart IIII). EMA worked closely 

with you and your office during the development of the proposed and final rules, and EMA 

member companies are now working to ensure final compliance to the standards established in 

the rule. 

Although EMA believes that the CI NSPS final rule generally adopts a technically 

feasible level of control for most categories of stationary CI engines, we have continuing 

concerns regarding the final NSPS rule as it applies to very large engines, those over 30 liters per 

cylinder (30 l/cyl). The requirements and emissions standards for those engines are identified in 

Section 60.4204 (c) and Section 60.4205 (d) of the final regulation. Manufacturers’ concerns 

include several issues that previously have been discussed with you in both written submittals 

and meetings over the last years. That correspondence included letters and comments submitted 

by EMA and Euromot dated 29 September 2006, 27 November 2006, 13 April 2007, and 29 June 

2007. We last addressed the issues at an EPA/EMA meeting at your offices on 27 August 2007.

Specifically, the previously identified issues that need resolution include the following:

 The NSPS establishes a single set of emission standards for engines greater than 30 l/cyl 

that do not recognize nor address the broad and diverse facility categories that utilize such 

engines. Further, these standards do not reflect best demonstrated technology.

 The NSPS exemption related to the use of aftertreatment technology on emergency engines 

also should apply to engines greater than 30 l/cyl.

 The geographic areas where higher sulfur fuels are allowed or that are subject to alternative 

emission requirements in the NSPS should be the same as allowed in other NSPS 

regulations.

 EPA Method 5 is not adequate to measure PM from engines larger than 30 l/cyl, and 

alternative methods are needed to improve accuracy.
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 The EPA should include provisions in the NSPS that incentivize and promote engines with 

high energy efficiency. EPA has included such provisions in final NSPS rules for other 

combustion technologies such as turbine and boilers. This issue applies to all engines and 

not only those with displacement greater than 30 l/cyl

The following text provides additional details and discussion on the above issues.

The emissions standards for engines greater than 30 l/cyl are not Best 

Demonstrated Technology and should be changed. 

EMA believes that some of the requirements imposed on engines greater than 30 l/cyl go

beyond EPA’s stated objective of the NSPS which is to “require all new, modified, and 

reconstructed stationary CI ICE to use best demonstrated systems of continuous emission 

reduction, considering cost, non-air quality health, and environmental and energy impacts, not 

just with add-on controls, but also by eliminating or reducing the formation of these pollutants” 

(Final Rule, CI ICE NSPS, FR 71: 39154, Summary). As applied to very large engines, the final 

NSPS exceed that objective by adopting emissions standards that require the use of systems that 

are not best demonstrated technology or that significantly adversely affect costs, non-air quality 

health, the effects of the standards on local air quality, and energy impacts. Specifically, the 

final emission standards for engines over 30 l/cyl do not provide flexibility to address local 

infrastructure, energy, or air quality conditions but mandate costly aftertreatment control systems 

for PM and NOx reductions.

As mentioned above, EPA has established a single set of emission standards for owners 

and operators for all stationary CI engines greater than 30 l/cyl. Owners and operators of such 

engines must reduce NOx emissions by 90% or achieve an emissions standard of 1.6 g/kW-hr, 

and must reduce PM by 60% or achieve an emissions standard of 0.15 g/kW-hr. Attaining the 

proposed standards will likely require the use of both NOx and PM aftertreatment technology. 

The rule does not provide sufficient transition time to develop and demonstrate the required 

technologies for these very large engines.

Furthermore, the wide range of facility and engine sizes, the application and location of a 

specific facility, the availability of low-sulfur diesel fuel in territories, and operating conditions 

are extremely varied. Aftertreatment to meet the final standards may not be technically or 

economically feasible under a given set of site conditions. Many remote applications that

depend on very large stationary diesel engines will be severely disadvantaged if products are not

available. 

As a solution for this issue, EMA proposes that the emission standards for stationary 

engines greater than 30 l/cyl should be harmonized with the recently approved International 

Maritime Organization (IMO) emissions regulations. Although there are technical differences 

between very large marine engines and stationary engines created for specific applications and 

duty cycles, there are correlations between the required engine development and demonstration 

programs. 
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First, the IMO, of which EPA is a key contributor and the US is now signatory, has 

approved at MEPC58 on October 9

th 2008 both Tier II standards and Tier III aftertreatment 

forcing standards covering engines of this size. The Tier III NOx standards will mandate 

compliance starting with new ship construction in 2016 to allow time for development of the 

required technologies. Engines and aftertreatment systems will need to be developed and 

available at that time to meet the IMO standards. Secondly, a stand-alone US EPA proposed 

rulemaking is currently underway for Marine engines greater than or equal to 30 l/cyl (Reference 

the EPA Federal Register release. [EPA–HQ–OAR–2007–0121; FRL–8502–5] RIN 2060–

AO38 Control of Emissions From New Marine Compression-Ignition Engines at or Above 30 

Liters per Cylinder). This US EPA proposed rulemaking is expected to harmonize with IMO 

requirements as well.

EMA believes a similar approach is warranted for very large stationary engines, which 

are nearly all derived from those somewhat higher volume, very large marine engines. Often the 

same engine types (with different turbo specifications) are used in both stationary and marine 

applications. One difference is that very large marine engines are IMO certified using lighter 

fuels whereas very large stationary engines meet World Bank/IFC standards using fuels available 

at the site. Another difference is that very large marine engines are developed with a focus on 

part-load performance and load-acceptance requirements and are typically optimized at an 85-

90% Maximum Continuous Rating(MCR) load range, whereas very large stationary engines are 

optimized for 100 % MCR load with less development at partial loads. One resulting difference 

is that marine and stationary plant engines have different turbo charger matching (different 

components in turbo chargers).

Since manufacturers are now required to meet IMO regulations for very large marine 

engines, the US is now a signatory to IMO, and EPA has promoted the IMO regulations for 

several years, EMA believes that the EPA should revise the NSPS for greater than 30 l/cyl 

engines to harmonize with IMO requirements for stationary engines. Engine manufacturers 

make both marine and stationary versions of these engine types. If EPA were to harmonize the 

requirements, manufacturers will be able to leverage development of solutions for both 

applications.

The NSPS exemption related to the use of aftertreatment technology on 

emergency CI engines should be applied to engines greater than 30 l/cyl to 

allow their use in emergency applications such as nuclear power system backup, firefighting, flood control, and national security.

In order to prevent potential performance and start-up problems when CI engines are 

used for emergency power generation, the final NSPS does not require owners or operators to 

use aftertreatment emissions control equipment on emergency generators. However, this critical 

exemption is not applied to engines greater than 30 l/cyl in the current rule.

For example, the nuclear power generation industry must provide back-up emergency 

power in order to assure the safe shut-down of the reactor in case of an emergency or disruption 

of off-site power. Due to their excellent performance and reliability characteristics, large diesel 
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generators are the preferred option for such back-up power systems. In many cases, the nuclear 

industry requires back-up power sources capable of generating 10 MW or more of power, and 

such generators will generally require IC engines with a 30 l/cyl displacement. However, in 

order to meet the emissions standards for greater than 30 l/cyl engines established in the final CI

NSPS, aftertreatment controls for PM and NOx will be needed. As in the case of smaller 

engines, the addition of such aftertreatment systems to meet current NSPS emission standards 

will jeopardize the ability of the engines to meet their primary safety function and performance 

standards required for emergency safety systems.

The primary function of emergency generators is to guarantee the power supply in case of 

loss of external electricity. EMA believes it is critical that the CI NSPS emissions standards do 

not interfere or jeopardize this critical function or prevent the use of large CI engines in 

emergency applications. As in the case of smaller emergency generators, large emergency 

generators will only be run for periodic and required safety tests and in the case of an emergency. 

Since EPA has adopted an exemption to the emissions limits for emergency diesel 

generators where meeting the emissions limits would require the use of aftertreatment devices 

and EPA has provided an exemption from NOx emissions limits for combustion turbines used in 

emergency situations1, it follows that the same exemption should be allowed for engines greater 

than 30 l/cyl that are used to provide emergency back-up power. In order to address this 

situation, the final CI NSPS should be amended to establish emissions standards for emergency 

engines with a displacement greater than 30 l/cyl that can be achieved during emergency 

operating conditions and during limited maintenance & readiness testing (as defined in the final 

CI NSPS paragraph 60.4211 e) without the addition of aftertreatment PM or NOx controls. As 

stated above, EMA recommends harmonization with the IMO standards. 

For emergency-use stationary CI engines greater than 30 l/cyl, we recommend that a 

slightly modified IMO Tier II standard be adopted and become effective in January 2011 and 

that the IMO Tier 1standards be adopted until that time The current requirement in the CI

NSPS (40 CFR 60.4213) to conduct tests within 10% of 100 percent peak load (or the highest 

achievable load) is appropriate since it reflects the actual operations and usage of the stationary

engine. EMA recommends that the CI NCPS be amended to state that performance tests for 

slightly modified IMO Tiers I and II also be conducted within 10 % of 100 percent peak load or 

the highest achievable load of the engine. The CI NSPS ruling also requires an annual 

performance test to demonstrate compliance with the set emission limits. EMA recommends that 

the simplified measurement method and allowances stipulated in Sections 6.3.11 and 6.4.15.2 of 

the IMO MEPC58 Revised Marpol Annex VI October 2008 be used for emissions measurements 

of engines at the site. 

 

1 US EPA 2006. Final Rule. Standards of Performance for Stationary Combustion Turbines. Federal 

Register, 78: p 38497.
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The geographic areas allowed to use higher sulphur content fuels or 

that are subject to alternative emissions requirements in the CI NSPS should 

be the same as allowed in other NSPS regulations.

EPA has recognized that certain geographical areas, because of their isolation from the 

mainland US or environmental conditions, warrant exceptions to the provisions in the CI NSPS 

governing fuel quality or permissible emissions. For example, the CI NSPS excludes the 

American territories of Guam, America Samoa and the Northern Mariana Islands from the fuel 

sulfur content requirement. Consequently, emissions standards from engines in such locations 

should not be as stringent since the quality of fuel in those locations is different.

Although EMA believes such exceptions are necessary and commendable, we are 

concerned that various EPA NSPS rules are not consistent in defining such areas or in allowing 

alternative emission standards for such areas.

Specifically, in both the combustion turbine rule and the steam generator boiler rule, the 

geographic areas defined as non-continental or territories are expanded to include the Hawaiian 

Islands, Virgin Islands, and Puerto Rico and offshore platforms. The same definition and 

allowances for different fuel quality available in those locations should be applied to the CI 

NSPS as well, i.e., the geographic exemptions should be the same in all rules and thus expanded 

in the CI NSPS rule.

In addition, EMA believes that remote areas that experience harsh environmental 

conditions, such as remote areas in Alaska, require additional exemptions from the fuel and 

emissions limits in the CI NSPS. The harsh environmental conditions in those locations make 

compliance to the current NSPS emissions extremely problematic since they affect the 

applicability of aftertreatment technology such as SCR systems. In those areas, EMA 

recommends that secondary abatement techniques not be required due to the problems associated 

with reagent availability and equipment and system freezing. As an example, EPA established 

alternative and less stringent emissions standards for gas turbines operating north of the artic 

circle, in off-shore applications or operating at temperatures below zero degrees F. 

Similar provisions need to be incorporated into the CI NSPS. Alternative emissions 

standards should be adopted that are appropriate and achievable given the harsh environmental 

conditions present. As recommended previously, EMA supports harmonization with IMO 

standards for areas where higher fuel sulfur or fuels blended with used lubrication oil are 

allowed. In those areas, stationary CI engines >30 l/cyl should harmonize with a slightly 

modified IMO Tier II and Tier I that reflects the design rating of stationary engines (testing at 

steady state loads within 10 % of 100 percent peak load or the highest achievable load). 

For the particulate limit we propose the same particulate limits (steady state load within 10 % of 

100 percent peak load or the highest achievable load of the stationary engine) of the EU LCP 

BREF document (available at http://www.jrc.es/pub/english.cgi/d1254325/19Reference 

Document on Best Available Techniques for Large Combustion Plants (adopted July 2006) -

22Mb page 405, table 6.47) 30 mg/Nm3(15 % O2) for light fuel oil and distillates and 50 

mg/Nm3(15 % O2) for heavy fuel oils with measurement modified US EPA Method 5 or EPA 

17.
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EPA Method 5 is not an adequate method to measure PM from large 

engines.

EPA requires owners and operators of engines greater than 30 l/cyl to use EPA Method 5 

to measure PM for performance and compliance demonstrations (NSPS Table 7(d) (IV)). 

Method 5 requires that the PM sample be taken at a cooled exhaust temperature of about 120 

degrees C (248 degree F). The flue gas temperature of larger CI ICE is typically in the range of 

250-350 degree C (480 – 660 degree F). Consequently, owners and operators will have to cool

flue gas from such engines in order to reach the Method 5 described filter holder temperature. 

According to the CIMAC document2this will result in large uncertainties (non-reproducible 

sampling): Appendix 2“. The cooling of the exhaust gas cannot be considered as a controlled 

process and will not yield reproducible sampling. The main reason for this is the uncontrolled 

condensation of semi-volatile components from the exhaust gas on the cold surfaces needed to 

cool the gas. According to ISO 9096 and EN 13284-1, more reproducible results are achieved if 

volatile compounds are not trapped during sampling or further evaporated during sample 

drying. Considering the above issues it is concluded that to yield repeatable particulate matter 

measurement data from the hot exhaust gas of a diesel engine, the particulate sampling has to be 

performed at exhaust gas temperature, i.e. using in-stack sampling”. 

Measurement methods EN 13284-1 (EU), JIS Z8808 (Japan) and ISO 9096 apply instack sampling of particulate in the case of flue gas temperatures greater than 160 degree C (320 

degree F). US EPA Method 17 provides an option similar in principal to those methods. In the 

case of flue gas temperatures less than 160 degree C (320 degree F), stack-out particulate 

sampling is used, and the filter holder temperature is maintained at minimum 160 degree C (320 

degree F) in order to avoid risk of condensation and absorption of sulphur compounds, water, 

etc. on the sampling filter. 

In order to avoid the problems associated with use of Method 5 for engines greater than 

30 l/cyl, EMA believes that the NSPS should provide flexibility and allow the use of Method 17 

to measure particulate matter. EPA has allowed such flexibility in other rules, specifically the 

NSPS rule for electric utility steam generating units and industrial-commercial steam generating 

units as published in the Federal Register on June 13, 2007.3 In that rule, EPA has specified an 

“own specific” particulate filter holding temperature and thus approved a higher filter holder 

temperature than 120 +/- 14 degree C (248 +/- 25 degree F) for the US EPA Method 5. The rule 

also provides flexibility and the use of Method 17, and indicates that steam generating units shall 

use particulate measurement methods 5, 5B or 17.

 

2 CIMAC Recommendation 23. Standards and Methods for Sampling and Analyzing Emission 

Components in Non-automotive Diesel Engine Exhaust Gases – Marine and Land-based Power Plant 

Sources. CIMAC working group on Exhaust Emissions, 2005. 

3 US EPA. Federal Register Notice Final Rule Amendments to NSPS Standards, June 13. 2007. FR 72: 

Page 32738.
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Different prime mover technologies should have fair and equal treatment under EPA 

regulations, and if flexibility and alternative filter holding temperatures are provided for one 

prime mover technology, than a similar and applicable requirement should be allowed for other 

prime mover technologies.

EMA recommends that the requirements of the CI NSPS be amended to allow owners 

and operators to use Method 17, and where engine stack temperatures are less than 160 degree C

(320 degree F) (in wet flue gas desulphurization stacks, etc.) to allow the use of Method 5B 

instead of Method 5 in order to get reproducible measurement results and avoid 

uncontrollable/difficult measuring conditions. Such procedures also align with applicable 

regulations in Japan and European countries.

EPA should encourage energy efficiency and fuel savings technology by 

adding an energy efficiency provision in the CI NSPS.

The impact of EPA regulations on energy use should be a key consideration when 

developing and finalizing emission standards as described in the recent EPA ANPRM on 

greenhouse gas emissions. The NSPS should include provisions promoting energy and fuel 

efficiency, reducing fuel use through the use of combustion sources with high fuel-energy 

conversion rates is a key element of federal energy policy to reduce the nation’s dependence on 

imported petroleum. Further, the use of high efficiency engines also results in lower greenhouse 

gas emissions and can be an effective way to reduce greenhouse gas emissions. 

EPA should include a provision within the CI NSPS that provides an energy efficiency 

incentive allowing increases in the emission of criteria pollutants for engines and generation 

systems that meet certain thresholds of energy efficiency. EPA has already adopted such 

incentives for other technology in NSPS regulations governing steam generator boilers, and 

stationary combustion turbines as follows:

US Steam-generating (boiler) unit NSPS, page 32739: “For the purposes of determining 

compliance with the emission limits in paragraph 60.45Da the owner or operator of 

generating unit which is also a cogeneration unit shall .. calculate emission rates based 

on electrical output to the grid plus 75 percent of the equivalent electrical energy 

(measured relative to ISO conditions) in the unit’s process stream.” Note paragraph 

60.45Da is for the Hg emission, i.e., a 75 % bonus for the recovered heat.

US stationary combustion turbine NSPS, page 38499: “... For combined-cycle and 

combined heat and power complying with the output-standard ...gross energy output is 

calculated as the sum of the total electrical and mechanical energy generated by the 

combustion turbine, the additional electrical or mechanical energy (if any) generated by 

the steam turbine .. and 100 percent of the total useful thermal energy output that is not 

used to generate additional electricity or mechanical output expressed in equivalent MW 

..” 
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Note Emission bonus is applied on the regulated emissions: NOx and SO2, i.e., a 100 % 

bonus for the recovered heat and full bonus for extra generated electrical/mechanical 

energy  (e.g. a 30 % electrical + 60 % heat recovery = 90 % efficiency  emission 

limit 3 times higher compared to the electricity production only case).

EMA requests that EPA develop and incorporate a similar efficiency provision for CI

engines. Adoption of such as program will recognize the importance of energy efficiency and 

the benefits of reducing fuel use and greenhouse gas emissions. Moreover, incorporating 

efficiency considerations in the regulation will provide a level playing field for engine-based 

systems compared to boilers and turbine that can already take advantage of such energy 

efficiency provisions in NSPS regulations governing those technologies. EMA is prepared to 

work out an efficiency provision together with US EPA.

Summary

EMA appreciates the opportunity to bring the above issues with the CI NSPS to your 

attention and to provide some additional background information on these topics. With the 

finalization of the SI NSPS, we believe it is an appropriate time to resolve these issues and ask 

that EPA consider making the necessary revisions to the CI NSPS as soon as possible. We 

would be happy to discuss these items with you and suggest that we set up a meeting date in 

January to discuss and resolve these issues.

Please feel free to call me if you have any questions.

Respectfully submitted,

Joseph L. Suchecki

Joseph L. Suchecki

Director, Public Affairs