                  UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                          SECTOR POLICIES AND PROGRAMS DIVISION
                       OFFICE OF AIR QUALITY PLANNING AND STANDARDS
                               OFFICE OF AIR AND RADIATION


DATE:		March 27, 2023

SUBJECT:	Stakeholder Meetings on Emergency Engine 50-Hour Provisions 
	
FROM:	Christopher Werner (EPA/OAR/OAQPS/SPPD/ESG)
			
TO:		Docket No. EPA-HQ-OAR-2022-0879


The purpose of this memorandum is to present a summary of several information-gathering meetings that took place between members of various stakeholder groups and the EPA since the Court of the Appeals for the D.C. Circuit granted EPA's request for voluntary remand of provisions appearing in the NESHAP and NSPS specifying that emergency engines can operate for up to 50 hours per year to mitigate local transmission and/or distribution limitations so as to avert potential voltage collapse or line overloads that could lead to the interruption of power supply in a local area or region. These meetings took place to attempt to gather information from stakeholders regarding the use of these provisions, which are often referred to as the "50-hour provisions." 

Meeting Dates: September 8, October 7, November 10, and December 14, 2021
Stakeholder Groups: American Public Power Association (APPA), National Rural Electric Cooperative Association (NRECA)

Meeting Dates: November 14, 2022
Stakeholder Groups: APPA, NRECA, Blue Sky Environmental LLC, Enel X North America, Consumers Power

In the meetings, EPA noted that a review of the information reported electronically to EPA on usage of engines for the 50-hour provision indicated that there appeared to be very little usage for the purpose of mitigating local transmission and/or distribution limitations so as to avert potential voltage collapse or line overloads that could lead to the interruption of power supply in a local area or region. Stakeholders did not provide specific additional information to the EPA on prior, current or anticipated future use of provision beyond some characterization of late reporting (i.e., that one entity has been using the provision, but did not submit reporting of this use until recently).

We are providing in the docket files containing all data electronically reported to EPA on use of the 50-hour provision over the last few years. We note that some entities appear to report use of the 50-hour provision in circumstances when other regulatory provisions allowing operation of the engines (such as readiness testing pursuant to 40 CFR 63.6640(f)(2)(i)) would appear to be more appropriate. The data is contained in three separate Excel files, each corresponding to the appropriate rule - NSPS (IIII), NSPS (JJJJ), and NESHAP (ZZZZ). 



