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Understanding the Stationary Engines Rules

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How does EPA regulate stationary engines?

EPA air quality requirements for stationary engines differ according to:

  • whether the engine is new or existing, and
  • whether the engine is located at an area source or major source and whether the engine is a compression ignition or a spark ignition engine. "Spark ignition" engines are further subdivided by power cycle - i.e., two vs. four stroke, and whether the engine is "rich burn" (burning with a higher amount of fuel as compared to air) or "lean burn" (less fuel compared to air) engine.

Several regulations have expanded the number and type of stationary RICE that must comply with federal requirements. These include:

Which types of engines are covered by the rules?

  1. Engines >500 Horsepower (HP) at major source of HAP:
    Existing engines if constructed before December 19, 2002
    New engines if constructed on or after December 19, 2002
    Reconstructed engines if reconstruction began on or after December 19, 2002
  2. Engines ≤500 HP located at major source of HAP and engines of all horsepower located at an area source of HAP:
    Existing engines if constructed before June 12, 2006
    New engines if constructed on or after June 12, 2006
    Reconstructed engines if reconstruction began on or after June 12, 2006

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Which types of engines are NOT covered by the rules?

  1. Motor vehicles, or to non-road engines, which are:
    • self-propelled (tractors, bulldozers)
    • propelled while performing their function (lawnmowers)
    • portable or transportable (has wheels, skids, carrying handles, dolly, trailer or platform). Note: a portable non-road engine becomes stationary if it stays in one location for more than 12 months (or full annual operating period of a seasonal source)
  2. Existing emergency engines located at residential, institutional, or commercial area sources and not used for local reliability. Engine must meet Subpart ZZZZ emergency engine operational requirements:
    • Unlimited use for emergencies (e.g., power outage, fire, flood)
    • Emergency engines may operate for 100 hr/yr for maintenance/testing
    • 50 hr/yr of the 100 hr/yr allocation can be used for:
      1. non-emergency situations if no financial arrangement
      2. local reliability as part of a financial arrangement with another entity if specific criteria met (existing RICE at area sources of HAP only).

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