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Technology Transfer Network - OAR Policy and Guidance

OAR Policy and Guidance Metarecord

Document Title/Subject:
Calculating PTE for Emergency Generators
Related Documents:
Signed by: John Seitz

Signature Date: September 6, 1995

Tim Smith, Information Transfer & Program Integration Division, OAQPS



Regulatory Authority:
Title 5
Information Transfer and Program Integration Division (OAQPS)
Submitted By:
Document Type:
Policy & Guidance Memos
EPA Document Number:

Federal Register:
Subject Category:
Operating Permits
Air pollutants
Clean Air Act
This is a 9/6/95 memo to the Regional Air Directors from John Seitz concerning calculation of potential to emit (PTE) for emergency generators. Inherent physical limitations, and operational design features which restrict the potential emissions of individual emission units, can be taken into account in determining PTE. The EPA believes that generators devoted to emergency uses are clearly constrained in their operation, in the sense that, by definition and design, they are used only during periods where electric power from public utilities is unavailable. The combined period for such power outages during any one year will vary somewhat, but an upper bound can be estimated which would never be expected to be exceeded absent extraordinary circumstances. Also, the duration of these outages are entirely beyond the control of the source; when they do occur, they rarely last more than a day. EPA, therefore, recommends that the PTE of emergency generators be determined based upon an estimate of the maximum amount of hours the generator could operate, taking into account: (1) the number of hours power would be expected to be unavailable and (2) the number of hours for maintenance activities. An appropriate default assumption is 500 hours per year. (4 pages)

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