---
kind: "section"
citation: "42 U.S.C. § 7651f"
title: "42"
title_heading: "The Public Health and Welfare"
number: "7651f"
heading: "Nitrogen oxides emission reduction program"
release: "119-102"
date: "2026-07-12"
url: "https://uscodex.org/usc/42/7651f"
units:
  - "Chapter 85 — Air Pollution Prevention and Control"
  - "Subchapter IV–A — Acid Deposition Control"
---

# §7651f. Nitrogen oxides emission reduction program

- (a) **Applicability—** On the date that a coal-fired [utility unit](/usc/42/7651a.md?p=17-A) becomes an [affected unit](/usc/42/7651a.md?p=2) pursuant to sections 7651c, 7651d,[^1] [7651h](/usc/42/7651h.md) of this title, or on the date a [unit](/usc/42/7651a.md?p=15) subject to the provisions of section [7651c(d)](/usc/42/7651c.md?p=d) or [7651h(b)](/usc/42/7651h.md?p=b) of this title, must meet the SO<sub>2</sub> reduction requirements, each such [unit](/usc/42/7651a.md?p=15) shall become an [affected unit](/usc/42/7651a.md?p=2) for purposes of this section and shall be subject to the [emission limitations](/usc/42/7602.md?p=k) for nitrogen oxides set forth herein.
- (b) **Emission limitations—**
  - (1) Not later than eighteen months after November 15, 1990, the [Administrator](/usc/42/7602.md?p=a) shall by regulation establish annual allowable [emission limitations](/usc/42/7602.md?p=k) for nitrogen oxides for the types of utility boilers listed below, which limitations shall not exceed the rates listed below: Provided, That the [Administrator](/usc/42/7602.md?p=a) may set a rate higher than that listed for any type of utility boiler if the [Administrator](/usc/42/7602.md?p=a) finds that the maximum listed rate for that boiler type cannot be achieved using low NO<sub>x</sub> burner technology. The maximum allowable emission rates are as follows:
    - (A) for tangentially fired boilers, 0.45 lb/mmBtu;
    - (B) for dry bottom wall-fired boilers (other than [units](/usc/42/7651a.md?p=15) applying cell burner technology), 0.50 lb/mmBtu.

    After January 1, 1995, it shall be unlawful for any [unit](/usc/42/7651a.md?p=15) that is an [affected unit](/usc/42/7651a.md?p=2) on that date and is of the type listed in this paragraph to emit nitrogen oxides in excess of the emission rates set by the [Administrator](/usc/42/7602.md?p=a) pursuant to this paragraph.

  - (2) Not later than January 1, 1997, the [Administrator](/usc/42/7602.md?p=a) shall, by regulation, establish allowable [emission limitations](/usc/42/7602.md?p=k) on a lb/mmBtu, annual average basis, for nitrogen oxides for the following types of utility boilers:
    - (A) wet bottom wall-fired boilers;
    - (B) cyclones;
    - (C) [units](/usc/42/7651a.md?p=15) applying cell burner technology;
    - (D) all other types of utility boilers.

    The [Administrator](/usc/42/7602.md?p=a) shall base such rates on the degree of reduction achievable through the retrofit application of the best system of continuous emission reduction, taking into account available technology, costs and energy and environmental impacts; and which is comparable to the costs of nitrogen oxides controls set pursuant to [subsection (b)(1)](#b-1). Not later than January 1, 1997, the [Administrator](/usc/42/7602.md?p=a) may revise the applicable [emission limitations](/usc/42/7602.md?p=k) for tangentially fired and dry bottom, wall-fired boilers (other than cell burners) to be more stringent if the [Administrator](/usc/42/7602.md?p=a) determines that more effective low NO<sub>x</sub> burner technology is available: Provided, That, no [unit](/usc/42/7651a.md?p=15) that is an [affected unit](/usc/42/7651a.md?p=2) pursuant to [section 7651c of this title](/usc/42/7651c.md) and that is subject to the requirements of [subsection (b)(1)](#b-1), shall be subject to the revised [emission limitations](/usc/42/7602.md?p=k), if any.

- (c) **Revised performance standards—**
  - (1) [^2] Not later than January 1, 1993, the [Administrator](/usc/42/7602.md?p=a) shall propose revised standards of performance to [section 7411 of this title](/usc/42/7411.md) for nitrogen oxides emissions from fossil-fuel fired steam generating [units](/usc/42/7651a.md?p=15), including both electric utility and [nonutility units](/usc/42/7651a.md?p=25). Not later than January 1, 1994, the [Administrator](/usc/42/7602.md?p=a) shall promulgate such revised standards of performance. Such revised standards of performance shall reflect improvements in methods for the reduction of emissions of oxides of nitrogen.
- (d) **Alternative emission limitations—** The [permitting authority](/usc/42/7651a.md?p=11) shall, upon request of an [owner](/usc/42/13641.md?p=4) or operator of a [unit](/usc/42/7651a.md?p=15) subject to this section, authorize an [emission limitation](/usc/42/7602.md?p=k) less stringent than the applicable limitation established under subsection [(b)(1)](#b-1) or [(b)(2)](#b-2) upon a determination that—
  - (1) a [unit](/usc/42/7651a.md?p=15) subject to [subsection (b)(1)](#b-1) cannot meet the applicable limitation using low NO<sub>x</sub> burner technology; or
  - (2) a [unit](/usc/42/7651a.md?p=15) subject to [subsection (b)(2)](#b-2) cannot meet the applicable rate using the technology on which the [Administrator](/usc/42/7602.md?p=a) based the applicable [emission limitation](/usc/42/7602.md?p=k).

  The [permitting authority](/usc/42/7651a.md?p=11) shall base such determination upon a showing satisfactory to the [permitting authority](/usc/42/7651a.md?p=11), in accordance with regulations established by the [Administrator](/usc/42/7602.md?p=a) not later than eighteen months after November 15, 1990, that the [owner](/usc/42/13641.md?p=4) or operator—

  - (1) has properly installed appropriate control equipment designed to meet the applicable emission rate;
  - (2) has properly operated such equipment for a period of fifteen months (or such other period of time as the [Administrator](/usc/42/7602.md?p=a) determines through the regulations), and provides operating and monitoring data for such period demonstrating that the [unit](/usc/42/7651a.md?p=15) cannot meet the applicable emission rate; and
  - (3) has specified an emission rate that such [unit](/usc/42/7651a.md?p=15) can meet on an annual average basis.

  The [permitting authority](/usc/42/7651a.md?p=11) shall issue an operating permit for the [unit](/usc/42/7651a.md?p=15) in question, in accordance with [section 7651g of this title](/usc/42/7651g.md) and part B[^3] of title III—

  - (i) that permits the [unit](/usc/42/7651a.md?p=15) during the demonstration period referred to in [subparagraph (2)](#d-2) above, to emit at a rate in excess of the applicable emission rate;
  - (ii) at the conclusion of the demonstration period to revise the operating permit to reflect the alternative emission rate demonstrated in paragraphs [(2)](#d-2) and [(3)](#d-3) above.

  [Units](/usc/42/7651a.md?p=15) subject to [subsection (b)(1)](#b-1) for which an alternative [emission limitation](/usc/42/7602.md?p=k) is established shall not be required to install any additional control technology beyond low NO<sub>x</sub> burners. Nothing in this section shall preclude an [owner](/usc/42/13641.md?p=4) or operator from installing and operating an alternative NO<sub>x</sub> control technology capable of achieving the applicable [emission limitation](/usc/42/7602.md?p=k). If the [owner](/usc/42/13641.md?p=4) or operator of a [unit](/usc/42/7651a.md?p=15) subject to the emissions limitation requirements of [subsection (b)(1)](#b-1) demonstrates to the satisfaction of the [Administrator](/usc/42/7602.md?p=a) that the technology necessary to meet such requirements is not in adequate supply to enable its installation and operation at the [unit](/usc/42/7651a.md?p=15), consistent with system reliability, by January 1, 1995, then the [Administrator](/usc/42/7602.md?p=a) shall extend the deadline for compliance for the [unit](/usc/42/7651a.md?p=15) by a period of 15 months. Any [owner](/usc/42/13641.md?p=4) or operator may petition the [Administrator](/usc/42/7602.md?p=a) to make a determination under the previous sentence. The [Administrator](/usc/42/7602.md?p=a) shall grant or deny such petition within 3 months of submittal.

- (e) **Emissions averaging—** In lieu of complying with the applicable [emission limitations](/usc/42/7602.md?p=k) under subsection [(b)(1)](#b-1), (2), or [(d)](#d), the [owner](/usc/42/13641.md?p=4) or operator of two or more [units](/usc/42/7651a.md?p=15) subject to one or more of the applicable [emission limitations](/usc/42/7602.md?p=k) set pursuant to these sections,[^4] may petition the [permitting authority](/usc/42/7651a.md?p=11) for alternative contemporaneous annual [emission limitations](/usc/42/7602.md?p=k) for such [units](/usc/42/7651a.md?p=15) that ensure that (1) the actual annual emission rate in pounds of nitrogen oxides per million Btu averaged over the [units](/usc/42/7651a.md?p=15) in question is a rate that is less than or equal to (2) the Btu-weighted average annual emission rate for the same [units](/usc/42/7651a.md?p=15) if they had been operated, during the same period of time, in compliance with limitations set in accordance with the applicable emission rates set pursuant to subsections [(b)(1)](#b-1) and (2).

  If the [permitting authority](/usc/42/7651a.md?p=11) determines, in accordance with regulations issued by the [Administrator](/usc/42/7602.md?p=a) not later than eighteen months after November 15, 1990;[^5] that the conditions in the paragraph above can be met, the [permitting authority](/usc/42/7651a.md?p=11) shall issue operating permits for such [units](/usc/42/7651a.md?p=15), in accordance with [section 7651g of this title](/usc/42/7651g.md) and part B[^3] of title III, that allow alternative contemporaneous annual [emission limitations](/usc/42/7602.md?p=k). Such [emission limitations](/usc/42/7602.md?p=k) shall only remain in effect while both [units](/usc/42/7651a.md?p=15) continue operation under the conditions specified in their respective operating permits.


## Footnotes

[^1]: So in original. Probably should be followed by “or”.
[^2]: So in original. No par. (2) has been enacted.
[^3]: See References in Text note below.
[^4]: So in original. Probably should be “subsections,”.
[^5]: So in original. The semicolon probably should be a comma.

## Source credit

(July 14, 1955, ch. 360, title IV, § 407, as added Pub. L. 101–549, title IV, § 401, Nov. 15, 1990, 104 Stat. 2613.)

## Notes

### Editorial Notes

### References in Text

Part B of title III, referred to in subsecs. (d) and (e), means title III of the Clean Air Act, act July 14, 1955, ch. 360, as added, which is classified to subchapter III of this chapter, but title III does not contain parts. For provisions of the Clean Air Act relating to permits, see subchapter V (§ 7661 et seq.) of this chapter.