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Technology Transfer Network - OAR Policy and Guidance





  • On June 28, 2006 the U.S. Environmental Protection Agency (EPA) issued final requirements to reduce emissions of air pollutants from stationary compression ignition (CI) internal combustion engines, also called stationary diesel engines.
  • Stationary diesel 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, known as New Source Performance Standards (NSPS), will limit emissions of nitrogen oxides (NOx), particulate matter (PM), sulfur dioxide (SO2), carbon monoxide (CO), and hydrocarbons (HC) from stationary diesel internal combustion engines to the same stringent levels required by EPAs nonroad diesel engine regulations.
  • At full implementation, EPA estimates that the total pollutant reductions will be more than 68,000 tons per year in 2015. The final rule will reduce NOx, PM, SO2, CO, and HC emissions gradually from 2005 to 2015, with overall reductions of 90 percent or more from baseline levels in some cases.
  • New, modified and reconstructed stationary diesel engines will be required to comply with the final rule. A new stationary diesel engine is one that is constructed or ordered, after July 11, 2005, the date the proposed standards were published in the Federal Register and manufactured after April 1, 2006. Stationary diesel engines that start modification or reconstruction after July 11, 2005 are also subject to the rule.
  • This final rule also contains fuel requirements that limit the amount of sulfur in the diesel fuel used to run these engines.
  • The rule will take effect in three increasingly stringent stages:
    1. The first stage is a transition period to control emissions from diesel engines built after this rule was proposed, but before the 2007 model year. Owners or operators will comply with this regulation by purchasing an appropriate engine and by operating and maintaining the engine according to the manufacturers’ instructions.
      • In most cases, the owner/operator will purchase a certified nonroad engine for stationary use and that will be sufficient to comply with the regulatory requirement.
      • In less likely cases, the owner/operator will purchase a uncertified engine and will have several options (using manufacturers emissions data or previous test results on a similar engine, or stack test data) to demonstrate compliance with the pre-2007 emission limits.
      • In all cases, the information which demonstrates new engine compliance and the appropriate maintenance records must be kept on site.
    2. Beginning in model year 2007:
      • Engine manufacturers will be required to certify that all new, modified or reconstructed stationary diesel engines meet the stringent emissions levels for NOx, PM, CO, and HC that are required for the same size engine and model year for nonroad diesel engines in the categories known as Tiers 1 through 4, with a few exceptions.
      • Stationary emergency diesel engines will be required to be certified to meet emissions limits through Tier 3 and also Tier 4, however, Tier 4 requirements for them do not require add-on controls.
    3. Beginning with 2011 model year engines, add-on controls will be required to achieve the emission limits for non-emergency engines.
  • By 2015, EPA estimates that 81,500 new stationary diesel engines will be subject to the rule.

  • The final rule will provide improvements in protecting human health and the environment by reducing pollutant emissions. Pollutants such as NOx and SO2 may cause both temporary and long-term respiratory symptoms, such as shortness of breath, changes in airway responsiveness, and increased susceptibility to respiratory infection.
  • NOx and SO2 also can form fine particle pollution. Exposure to fine particle pollution is associated with significant adverse health effects including shortness of breath, bronchitis, asthma attacks, heart attacks, and premature death. Diesel PM is likely carcinogenic and also contribute to a number of non-cancer health effects. Particle pollution also contributes to haze, which reduces visibility in cities and in our national parks and wilderness areas.
  • Both NOx and SO2 react with moisture in the atmosphere to form acid rain, which, when deposited, causes acidification of soil and surface waters.
  • NOx can react in the air to form ground-level ozone. Ozone can cause coughing, shortness of breath, and aggravate asthma and other chronic lung diseases such as emphysema and bronchitis. Ozone can lead to reduced lung function in both children and adults.
  • CO and HC are considered harmful to human health and the environment and are linked to various negative health conditions in humans.

  • EPA estimates the total national capital cost for the final rule to be $67 million in the year 2015, with a total nationwide annual cost of $57 million in the year 2015.

  • The Clean Air Act (CAA) requires EPA to promulgate NSPS for stationary diesel engines. The standards must consider emission control technologies available and costs of control.
  • NSPS are a statutory requirement under section 111 of the CAA. The original NSPS for stationary diesel engines were proposed in 1979, but were never finalized. EPA re-proposed the standards on June 29, 2005.
  • The schedule for completing this rule is part of a consent decree with Environmental Defense which requires the EPA Administrator complete a final rule by June 28, 2006.
  • Read the final rule posted in PDF format. (412 KB, 176 pp. PDF file; about PDF files).
  • Today's final rule and other background information are also available either electronically at http://www.regulations.gov/, EPA's electronic public docket and comment system, or in hardcopy at EPA's Air and Radiation Docket and Information Center, Environmental Protection Agency, Room B102, 1301 Constitution Avenue, NW, Washington, DC (Docket ID No. EPA-HQ-OAR-2005-0029). The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the Air and Radiation Docket and Information Center is (202) 566-1742.
  • For further information about the proposed rule, contact Mr. Jaime Pagán at EPAs Energy Strategies Group at 919-541-5340.
  • EPA's Office of Air and Radiation (OAR) home page on the Internet contains a wide range of information on the air toxics program, as well as many other air pollution programs and issues. The OAR home page address is: https://www.epa.gov/oar.

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