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

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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 NationsMs. 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