Gleaming ductwork from the top of a blue stationary emergency generator wraps around the open ceiling in a room with black-plastic-covered walls.

4 Steps to Managing Emergency Generators for EPA Engine Compliance

4 Steps to Managing Emergency Generators for EPA Engine Compliance

April 17, 2023
Jasmine Sodemann
Gleaming ductwork from the top of a blue stationary emergency generator wraps around the open ceiling in a room with black-plastic-covered walls.
Air quality compliance for emission sources, such as boilers and emergency generators, is enforced by federal, state, and local regulatory agencies.

As discussed in my previous blog, “Understanding Air Quality Requirements for Emergency Generators,” owning a stationary emergency generator means complying with regulatory obligations under a complex web of requirements issued by the U.S. Environmental Protection Agency (EPA).

These are known as the reciprocating internal combustion engine (RICE) rules. The RICE rules can seem overwhelming, with many narrowly specialized provisions. But this blog provides a four-step process to evaluate your engine and ensure regulatory compliance.

Step 1: Gather Engine Factors

Finding information about engine factors can be challenging. And each engine may require a different combination of investigation and research to gather the necessary factors for compliance.

To obtain the requisite data, you may need to:

  • Physically access locked panels on your generator to observe hidden nameplates.
  • Conduct online research on manufacturer publications and specifications.
  • Contact the manufacturer directly.
  • Review archived files.
  • Request a Certificate of Conformity from the EPA.

Identifying Facility and Source Type

The RICE National Emission Standards for Hazardous Air Pollutants (NESHAP) offers few exclusions from applicability.

But the facility type allows some emergency engines at commercial and institutional facilities to be excluded from the RICE NESHAP, making it very important to confirm the facility type you are evaluating. Facility types include commercial, institutional, and industrial. The EPA guidance memo listing NAICS codes can help define your facility type.

The source type refers to the facility-wide potential to emit hazardous air pollutants (HAP). Area sources are defined as having the potential to emit fewer than 10 tons per year of any single HAP and fewer than 25 tons per year of total HAPs combined. Major sources are those equal to or greater than these levels.

You should evaluate your existing facility air permits and emissions calculations to verify whether you may be a major source of HAPs. Major sources of HAPs require Federal Title V air permits. Requirements for emergency generators at HAP major sources differ from those at area sources, and the great majority of facilities will be non-major or area sources of HAPs.

Understanding Generator Fuel and Purpose

Fuel type is critical in determining regulatory requirements. Most emergency generators burn diesel fuel, natural gas, or propane. As a side note, diesel or oil-fired generators have fuel storage tanks that may have tank registration requirements and require Spill Prevention, Control, and Countermeasure (SPCC) planning. Remember to review for other potential environmental impacts, such as this, for your installation.

The purpose of your engine is also critical. Emergency and non-emergency engines have different requirements. For portable units, you must determine if they may be considered stationary, depending on how long they will remain at a location.

Differences in Emergency-Only Engine Use

Engines for emergency use have reduced RICE requirements. Still, it’s important to note that to maintain the reduced requirements, you must operate the generator according to the definition of emergency in the RICE rules:

  • An emergency engine is operated to provide electrical power during an emergency. Examples include stationary engines used to produce power for critical networks or equipment when electric power from the local utility is interrupted and stationary engines used to pump water for a fire or flood.
  • An emergency engine operates in non-emergency situations only for limited operation hours, as specified in the RICE rules.

If your engine purpose cannot meet the emergency definition, specify the engine as designed for non-emergency use.

If your search indicates an EPA Family Number or a certificate number, it is your lucky day! An EPA Certificate of Conformity documents that your engine was manufactured to the applicable New Source Performance Standards (NSPS). You can email the EPA to request a copy of a certificate from them. In your email request, provide the following details:

  • Model year of engine.
  • Type of engine, e.g., nonroad gasoline or diesel.
  • Manufacturer.
  • EPA Engine Family Number (printed on the emission label located on or near the engine).
  • Contact information, including your name, address, or email address where you want EPA to send the Certificate of Conformity.

Step 2: Evaluate Federal RICE Requirements

The RICE requirements are complex and challenging to navigate. Carefully step through the requirements, keeping your specific engine factors in mind. If you don’t have a construction date, you can use your engine model year to help you estimate.

Existing engines will be subject to the NESHAP unless excluded as an engine in an institutional facility with a model year before 2005. New engines must comply with the NSPS for compression ignition or spark ignition. Two engines with the same power rating but built at different times will have entirely different requirements. All of these factors may affect what RICE requirements apply to your engine.

Given its less stringent requirements, you may desire to meet the “emergency” definition. However, understand that the “emergency” definition limits demand response opportunities. If you wish to participate in non-emergency demand response, purchase a non-emergency generator.

Noncertified new engines may have stepped-up requirements, such as stack testing; check your specs carefully – be wary of terms such as “compliant capable.” This does not mean certified. Certified engines will have an EPA Family Number.

Navigating each of these rules is complicated. Use the factors in Step 1 to help understand and evaluate the applicable requirements. The EPA offers online guidance pages, including “Regulation Navigation Tools,” which you may find helpful.

Step 3: Evaluate State/Local Agency Requirements

While there may be commonalities, each state and some localities will have special requirements for RICE engines. This step is also where air permitting requirements will come into play.

There is too much variability across the U.S. to provide in-depth guidance for this step. Most states or localities will have regulatory codes that must be reviewed for applicability for an emissions source, such as a RICE engine. There is no shortcut to evaluating state and local requirements for a specific engine. In many cases, an air permit, if required, must be issued and “in hand” before initiating the site work for installation.

Create a summary of regulatory compliance information resulting from your engine evaluation. Feel free to reach out to me if you would like a copy of an example summary of air quality requirements for an emergency diesel engine.

A useful summary will document engine factors critical to the regulatory review, summarize the federal requirements, include a reference to the EPA Family Number, and give a reminder of the limitations of hours of operation as an emergency engine. It also will address the state agency’s environmental regulatory requirements, including permit coverage.

Step 4: Take Action for EPA Engine Compliance

After completing a thorough review and following steps 1-3, you will have the findings necessary to take action to comply with requirements. An emergency generator operation log is required for nearly every engine. An example can be provided by request. Feel free to reach out to me for a copy.

Other actions may be specific to state or local requirements and may include applying for a permit. However, many agencies have options for registration or general permitting that may reduce the permitting process burden.

Be sure to keep other mandatory records based on the requirements determined in your evaluation. Proceed with submitting a permit application if it is required for your generator as soon as possible. If you are proposing a new engine, these steps should be completed well in advance, perhaps 3-6 months before installing it.


As you may realize, these steps require a reasonable amount of time and effort. Baking them into your pre-construction project schedule can help ensure you build methods of compliance and receive the required permits before installation.

Gannett Fleming has the experience to guide you through this process and assist you with your facility’s emergency generator engine compliance. Whether you partner with us or go it alone, achieving compliance can help prevent the dreaded notice of violation or added costs and delays to your project. Learn more about our environmental, regulatory, and public outreach services and the value we can bring your organization.

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Jasmine Sodemann
Vice President, Environmental Compliance & Remediation

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