top of page
  • Writer's pictureTom Petersen

NSPS for Fossil-Fuel Fired Steam Generators and Steam Generating Units

Updated: Aug 29, 2023

In 2006 EPA finalized an update to the regulations for the Standards of Performance for Fossil-Fuel Fired Steam Generators and various Steam Generating Units (40 CFR 60 Subparts D, Da, Db, & Dc). The Utility Air Regulatory Group and the Council of Industrial Boiler Owners filed petitions for reconsideration on this regulation. These petitions resulted in an amended regulation which was promulgated on June 13, 2007.

While there weren’t many significant changes, the subparts were promulgated due to some language changes intended to make the regulation in its entirety more consistent. Therefore, if you are subject to this regulation, it would be worth while reading through the regs to ensure you are in compliance.


Systems subject to this regulation:

  1. Fossil Fuel Fired Steam Generators (Subpart D) with a maximum design heat input capacity of more than 73 MW are regulated for PM, SO2, & NOx.

  2. Electric Utility Steam Generating Units (Subpart Da) with a maximum design heat input capacity of more than 73 MW are regulated for SO2, NOx & Hg.

  3. Industrial-Commercial-Institutional Steam Generation Units (Subpart Db) with a maximum design heat input capacity of more than 29 MW are regulated for PM, SO2, & NOx.

  4. Small Industrial-Commercial-Institutional Steam Generation Units (Subpart Dc) with a maximum design heat input capacity greater than or equal to 2.9 MW but less than or equal to 29 MW are regulated for PM & SO2

This most recent update had a few minor modifications which are summarized below:

  1. CEMS/COMS monitoring alternatives: EPA included several alternatives to existing COMs requirements. This includes using a CO CEMS in place of COMs when burning gaseous fuels or low sulfur fuel oils and a combination of COMS, compliance tests & continuous control device monitoring for PM instead of PM CEMS (subpart Da).

  2. Part 75 NOx & SO2 CEMs calibration procedures: This was added as an option in subpart Da.

  3. Section 60.13: Standardized methodology for validating partial operating hours

  4. Calibration drift test: Now allowed to be conducted over 7 operating days instead of 7 calendar days.

  5. Subpart Db 30 day annual SO2 exemption: Expanded to include all units which burn coke oven gas.

  6. Subpart D NOx & SO2 Modifications: Additional emission limitation options.

Number 44 part 2


4 views
bottom of page