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New Hampshire Department of Environmental Services

DES Amends Definition of Emergency Generator

The New Hampshire Department of Environmental Services Air Resources Division recently made a change to New Hampshire Administrative Rule Env-A 1211.02(o), which defines the term "emergency generator." The definition of emergency generator was modified to allow owners of permitted emergency generators to participate in electric demand response programs and operate their emergency generators when the regional electric grid operator, ISO New England (ISO-NE), declares the implementation of Action 12 of ISO-NE Operating Procedure 4 (OP4), Action During a Capacity Deficiency. More information regarding demand response programs and the ISO-NE operating procedures can be found at the ISO-NE Web site at

Prior to the rule change, emergency generators were limited to operating only during periods when the primary power source for a facility was lost during an emergency, such as a power outage, and/or periods when the facility conducted normal maintenance and testing as recommended by the generator manufacturer. The new definition still allows for operation during these periods, but also allows for operation when ISO-NE declares OP4 Action 12. Operation of an emergency generator for any other purpose continues to be prohibited.

Specifically, the new definition prohibits emergency generators to be used as load shaving units, peaking power production units, or as a standby engines in an energy assistance program, which differs from operating under OP4 Action 12. If a source wishes to operate under these types of scenarios, they must first obtain an air permit that explicitly allows for non-emergency operation. Please also note that generators permitted for non-emergency use may be subject to additional fees and requirements under Env-A 3700, NOx Emissions Reduction Fund for NOx Emitting Generation Sources.

During the rule revision process, a question was raised regarding the fact that many sources currently hold permits that include the previous definition of "emergency generator," and whether sources wanting to operate during OP4 Action 12 events would need to amend their permits to reflect the new definition. Regardless of whether the emergency generator is permitted under a General State Permit, Temporary Permit, State Permit to Operate, or Title V Operating Permit, DES is not requiring these permits to be amended at this time. Instead, the permits will be amended as they are renewed. Further, in the interim, DES will assess compliance with a facility’s permit terms and conditions using the new definition.

If you are currently operating one or more emergency generators that are subject to permitting according to Env-A 607.01, and do not currently hold a permit for these devices, please submit application forms.

If you have any questions regarding the rule change please contact Gary Milbury of the Air Resources Division, Permitting and Environmental Health Bureau, at (603) 271-2630 or If you have questions regarding permitting procedures, please contact Barbara Dorfschmidt at (603) 271-6796 or

NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
(603) 271-3503 | TDD Access: Relay NH 1-800-735-2964 | Hours: M-F, 8am-4pm

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