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FACT SHEET: Proposed Amendments to the Standards for Performance for Stationary Compression Ignition Internal Combustion Engines


  • On October 30, 2015, the U.S. Environmental Protection Agency (EPA) proposed amendments to the standards of performance for stationary compression ignition (CI) internal combustion engines.

  • New stationary and nonroad CI engines are equipped by the engine manufacturer with emission controls to meet the Tier 4 final emission standards, which generally began with either the 2014 or 2015 model year.

  • When routine emission-control maintenance (such as diesel exhaust fluid refill) does not occur as designed, many Tier 4 engines are designed to reduce power to prevent excess emissions.

  • The proposed amendments would allow owners and operators to temporarily override these performance-related inducements when engines are needed to respond to an emergency where there is a risk to human life. This will facilitate the use of stationary engines to perform life-saving work during fires, floods, hurricanes, and other emergency situations.
    • Engine operators would be required to report the situations where they temporarily override inducements to engine manufacturers, and manufacturers will submit an annual report to EPA summarizing the use of the temporary override during the prior year.
  • The proposed amendments will also revise the criteria in the rule for defining remote areas of Alaska, which is currently defined as areas that are not accessible by the Federal Aid Highway System (FAHS). This proposal specifies that engines in areas of Alaska that are accessible by the FAHS can be considered in a remote area if each of the following conditions is met:
    1. The only connection to the FAHS is through the Alaska Marine Highway System, or the stationary CI engine operation is within an isolated grid in Alaska that is not connected to the statewide electrical grid referred to as the Alaska Railbelt Grid;

    2. At least 10 percent of the power generated by the engine on an annual basis is used for residential purposes; and

    3. The generating capacity of the facility is less than 12 megawatts, or the engine is used exclusively for backup power for renewable energy.

  • Under the current rule, engines in remote areas of Alaska are not required to meet the most stringent standards for nitrogen oxides (NOx), which effectively require the use of add-on emission controls. The state of Alaska provided information to EPA indicating that additional remote areas faced challenges that warrant allowing engines in the additional remote areas to meet a NOx standard that would not necessitate the use of add-on emission controls.

  • EPA will accept public comment for 45 days after the notice is published in the Federal Register.


  • The Clean Air Act (CAA) requires EPA to set New Source Performance Standards (NSPS) for stationary CI engines, which are generally diesel engines. The standards must consider available emission control technologies and costs of control.

  • On July 11, 2006, EPA issued standards of performance for stationary CI internal combustion engines. These engines are used at facilities such as power plants and chemical and manufacturing plants to generate electricity and to power pumps and compressors. They are also used in emergencies to produce electricity and to pump water for flood and fire control.

  • The final standards, limited emissions of nitrogen oxides (NOx), particulate matter (PM), sulfur dioxide (SO2), carbon monoxide (CO), and hydrocarbons (HC) from stationary CI internal combustion engines to the same stringent levels required by EPA’s nonroad diesel engine regulations. The final rule also limited the amount of sulfur in the diesel fuel used to run these engines.

  • In June 2011, EPA amended the final standards to align emissions limits for certain categories of stationary CI engines with similar sized engines used in marine applications.

How To Comment

  • EPA will accept comment on the notice for 45 days after publication in the Federal Register. Comments, identified by Docket ID Number EPA-HQ-OAR-2014-0866, may be submitted by one of the following methods:
    • Go to and follow the on-line instructions for submitting comments.
    • Send comments by e-mail to
    • Fax your comments to: (202) 566-9744.
    • Mail your comments to:

EPA Docket Center,
Environmental Protection Agency, Mail Code: 28221T
1200 Pennsylvania Ave., NW
Washington, DC 20460

  • Deliver your comments in person or via courier to:

EPA Docket Center
1301 Constitution Ave., NW
Room 3334
Washington, DC 20004

Such deliveries are only accepted during the Docket’s normal hours of operation, and special arrangements should be made for deliveries of boxed information.

For More Information

  • The notice of proposed rulemaking is posted at:

  • Today’s action and other background information are also available either electronically at, EPA’s electronic public docket and comment system, or in hardcopy at EPA Docket Center’s Public Reading Room.
    • The Public Reading Room is located in EPA Headquarters Library, Room Number 3334 in EPA WJC West Building, located at 1301 Constitution Ave., NW, Washington, DC. Hours of operation are 8:30 a.m. to 4:30 p.m. eastern standard time, Monday through Friday, excluding Federal holidays.
    • Visitors are required to show photographic identification, pass through a metal detector, and sign the EPA visitor log. All visitor materials will be processed through an X-ray machine as well. Visitors will be provided a badge that must be visible at all times.
    • Materials for this action can be accessed using Docket ID No. EPA-HQ-OAR-2014-0866.
  • For further information about the action, contact Ms. Melanie King of EPA’s Office of Air Quality Planning and Standards, Sector Policies and Programs Division, Energy Strategies Group at (919) 541-2469 or by e-mail at

Printable version of the fact sheet

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