Truck & Engine ems Manufacturers 

Association ® 

Bringing Cleaner Power to fhe World Since 1968 ® 

333 West Wacker Drive, Suite 810 

Chicago, Illinois 60606 

Tel: (312) 929-1970 1 Fax: (312) 929-1975 

www.truckandenginemanufacturers.org 

.` 

Jed R. Mandel 

(312) 929-1960 

jmandel@emamail.or>; 

August 7, 2014 

Ms. Melanie King 

Energy Strategies Group 

Sector Policies and Programs Division 

Office of Air Quality Planning and Standards 

U.S. Environmental Protection Agency 

109 T.W. Alexander Drive 

Mail Code: D243-01 

Research Triangle Park, NC 27711 

Dear Melanie: 

I am following up on my July 9, 2014 letter and our subsequent telephone conversations. 

You have asked me to provide a little more information about EMA's proposal for demonstrating 

compliance to a Tier 1"fall-back" emission standard for final Tier 4 compliant stationary 

engines that may need to override inducements in the event of an emergency. 

Requiring actual test cell based certification testing using the federal test procedure and 

meeting all of the regulatory requirements of Parts 1039 and 1065 would be unduly expensive 

and burdensome (for both manufacturers and EPA) -- and simply is unnecessary. Instead, EMA 

has proposed a cost-effective, workable, and fully enforceable alternative. Namely, 

manufacturers would provide EPA engine family specific data that they would show, using their 

"good engineering judgment", that the engine family in question would meet the Tier 1 NOx 

emission limit if its SCR based NOx control system were disabled. The term "good engineering 

judgment" is used repeatedly throughout Title 40 of the Code of Federal Regulations. In 

particular, EPA has defined that term at 40 C.F.R. 1068.30 as "judgments made consistent with 

generally accepted scientific and engineering principles and all available relevant information." 

An example of the kind of data (and "good engineering judgment") that a manufacturer 

might use will help illustrate how this form of certification compliance demonstration would 

work. Manufacturers have developed substantial data as part of their development of SCR 

emission control systems. They know, and can demonstrate with data, the conversion 

efficiencies of the specific SCR technology employed as part of an engine family's overall 

emission control design. Manufacturers can calculate, and EPA can verify by the data 

manufacturers would submit as part of its certification application, the emission profile of the 

engine family if the SCR system were disabled. So, for example, if a>560 kW genset engine 

family demonstrate compliance with the final Tier 4 NOx emission limit of 0.67 g/kW-hr using a 

SCR system efficiency no greater than 92.7%, then the NOx emission level of that engine with 

the SCR system disabled would meet the Tier 1 NOx limit of 9.2 g/kW-hr. Similarly, a<560 

kW engine that meets the Final Tier 4 NOx limit of 0.4 g/kW-hr with an SCR conversion 

A Non Governmental Organization in Special Consultative Status with the Economic and Social Council of the United Nations 
Ms. Melanie King 

August7, 2014 

Page 2 

efficiency no greater than 95.7% would meet the Tier 1 emission limit of 9.2 kW-hr if the SCR 

system were disabled. 

The above examples are, of course, just that — examples. For actual certification 

applications, manufacturers would submit the actual conversion efficiencies, as determined and 

substantiated by data, and, then, using their good engineering judgment (in this case, essentially, 

the application of simple mathematics) demonstrate conclusively what the NOx emission level 

would be if the SCR system were disabled. So long as that NOx emission level met or exceeded 

the applicable Tier 1 NOx limit, the engine could be certified. 

On top of that, in order to provide EPA every assurance of compliance and enforceability, 

EMA has proposed that EPA also retain, and use as necessary, its confirmatory testing authority. 

Using that authority, EPA could issue an order requiring a manufacturer to make the original 

certification engine available to EPA to confirmatory test for compliance. EPA would be able to 

test that engine for compliance with both the final Tier 4 standard and, after disabling the SCR 

system, the Tier 1 standard, as well. 

We believe the proposed certification compliance demonstration approach outlined above 

is both technically and fiscally sound, legally enforceable, and valid under the Clean Air Act and 

EPA's implementing regulations. I note that EPA has adopted rules in the past where 

compliance is demonstrated through means other than the generation of certification data. See, 

for example, 40 C.F.R. 1039.205(p) which states: 

State that all the engines in the engine family comply with the not-toexceed emission standards we specify in subpart B of this part for all 

normal operation and use when tested as specified in § 1039.515. Describe 

any relevant testing, engineering analysis, or other information in 

sufficient detail to support your statement. 

Please let me know if you have any questions. I would be happy to discuss this matter 

with you further. 

VQr_y_truly yours, 

Jed Mandel 

President