Chapter NR 428

NR 428.01(1) (1) Applicability. This chapter applies to all air contaminant sources which emit nitrogen compounds and to their owners and operators. All references to the code of federal regulations in this chapter mean those parts or provisions as in effect on February 1, 2001, except that in the case of CFR appendices incorporated by reference in ch. NR 484, if a more recent date is specified in the applicable section of ch. NR 484, that date shall apply.

NR 428.01(2) (2) Purpose. This chapter is adopted under ss. 285.11, 285.13 and 285.17, Stats., to categorize nitrogen compound air contaminant sources and to establish emission limitations and other requirements for these sources in order to protect air quality.

NR 428.01 History History: Cr. Register, September, 1986, No. 369, eff. 10-1-86; am. (1), Register, May, 1992, No. 437, eff. 6-1-92; am. Register, January, 2001, No. 541, eff. 2-1-01.

NR 428.02 NR 428.02 Definitions. The definitions contained in ch. NR 400 apply to the terms used in this chapter. In addition, the following definitions apply to the terms used in this chapter:

NR 428.02(1) (1) “Biologically derived gaseous fuel” means a gaseous fuel resulting from biological processing of a carbon-based feedstock.

NR 428.02(1m) (1m) “Capacity factor” means one of the following:

NR 428.02(1m)(a) (a) The ratio of a unit’s actual electric output (expressed in MWe-hr) to the unit’s nameplate capacity times the unit’s potential hours of operation. The potential hours of operation on an annual basis are 8,760 hours, and on an ozone season basis are 3,672 hours.

NR 428.02(1m)(b) (b) The ratio of a unit’s heat input (in million Btu or equivalent units of measure) to the unit’s maximum design heat input (in million Btu per hour or equivalent units of measure) times the unit’s potential hours of operation.

NR 428.02(2) (2) “Combined cycle system” means a system comprised of one or more combustion turbines, heat recovery steam generators and steam turbines configured to improve overall efficiency of electricity generation or steam production.

NR 428.02(3) (3) “Combustion controls” has the meaning given in s. NR 409.02 (21m).

NR 428.02(4) (4) “Combustion optimization” means those activities necessary to maximize combustion efficiency while minimizing NOx emissions, including but not limited to the following: burner adjustments, fuel conditioning, fuel flow improvements, furnace design modifications and the application of combustion controls.

NR 428.02(5) (5) “Combustion turbine” means an enclosed fossil or other fuel-fired device that is comprised of a compressor, a combustor and a turbine, and in which the flue gas resulting from the combustion of fuel in the combustor passes through the turbine, rotating the turbine.

NR 428.02(6) (6) “Commencement of operation” means the beginning of any mechanical, chemical or electronic process, including, with regard to a unit, startup of a unit’s combustion chamber.

NR 428.02(6m) (6m) “Integrated gasification process” means a high temperature process in which gaseous fuel is produced onsite from a carbon-based feedstock.

NR 428.02(7) (7) “Kraft recovery boiler” means “recovery furnace”, as defined in s. NR 440.45 (2) (L).

NR 428.02(7e) (7e) “Maximum theoretical emissions” means the quantity of NOx emissions that theoretically could be emitted by a stationary source without consideration of control devices based on the design capacity or maximum production capacity of the source and 8,760 hours of operation per year. When appropriate, and upon request by the source owner or operator, maximum theoretical emissions may be limited by the imposition of conditions in a federally enforceable permit. The conditions shall be used in place of design capacity or maximum production capacity in calculating the maximum theoretical emissions for the source and may include, among other things, the establishment of production limitations, capacity limitations, or limitations on the hours of operation of any emission source, or a combination of any limitations. Production or capacity limitations shall be established on the basis of no longer than one month and may allow for averaging for up to 12 consecutive months.

NR 428.02(7i) (7i) “Primary fuel” means the fuel types that provide the greatest amount of heat input, in terms of mmBtu, to a combustion unit. A combustion unit may have more than one primary fuel.

NR 428.02(7m) (7m) “Process heater” means an enclosed device using controlled flame, that is not a boiler, and that has a primary purpose to transfer heat indirectly to a process material or to a heat transfer material for use in a process unit, instead of generating steam. Process heaters may not include combustion equipment where the material being heated is in direct contact with the products of combustion, such as furnaces or kilns, any unfired waste heat recovery heater or units used for comfort heat or space heat, food preparation for onsite consumption, or autoclaves.

NR 428.02(7p) (7p) “Secondary fuel” means any fuel that is not a primary fuel.

NR 428.02(7u) (7u) “Simple cycle stationary combustion turbine” means any stationary combustion turbine that does not recover heat from the stationary combustion turbine exhaust gases.

NR 428.02(7w) (7w) 

NR 428.02(7w)(a) (a) “Supply interruption” or “curtailment” means a period of time during which the supply of primary fuel to an emissions unit is reduced for reasons beyond the control of the facility.

NR 428.02(7w)(b) (b) “Supply interruption” or “curtailment” may not result from an increase in the cost or unit price of the primary fuel.

NR 428.02(8) (8) “Unit” means a solid fuel-fired or fossil fuel-fired combustion device.

NR 428.02 History History: Cr. (intro.), renum. from NR 154.01 (122), Register, September, 1986, No. 369, eff. 10-1-86; am. (intro.), r. (1), Register, June, 1993, No. 450, eff. 7-1-93; am. (intro.), cr. (1) to (8), Register, January, 2001, No. 541, eff. 2-1-01; CR 02-076: cr. (6m) Register November 2002 No. 563, eff. 12-1-02; CR 03-049: renum. (1) to be (1m), cr. (1) Register December 2003 No. 576, eff. 1-1-04; CR 07-016: cr. (7m) Register July 2007 No. 619, eff. 8-1-07; CR 08-103: cr. (7e) Register August 2009 No. 644, eff. 9-1-09; CR 23-017: cr. (7i), (7p), (7u), (7w) Register March 2024 No. 819, eff. 4-1-24.

NR 428.03 NR 428.03 General limitations. No person may cause, allow or permit nitrogen oxides or nitrogen compounds to be emitted to the ambient air which substantially contribute to the exceeding of an air standard or cause air pollution.

NR 428.03 History History: Renum. from NR 154.15 (1), Register, September, 1986, No. 369, eff. 10-1-86; am. Register, May, 1992, No. 437, eff. 6-1-92.

subch. I of ch. NR 428 Subchapter I — NOx Emissions Performance Program General Provisions

NR 428.04 NR 428.04 Requirements and performance standards for new or modified sources.

NR 428.04(1) (1) Applicability. The requirements of this section apply to emissions units described in this section that are located in the county of Kenosha, Milwaukee, Ozaukee, Racine, Washington or Waukesha and that are constructed or that undergo a major modification, as that term is described in ch. NR 405 or 408, after February 1, 2001. When determining whether an emissions unit undergoes a major modification for purposes of this section, any increase in CO emissions resulting from the operation of the emissions unit, or operation of NOx emissions control equipment for purposes of meeting state or federal NOx emission requirements, will not be considered in the emissions calculations.

NR 428.04(2) (2) Performance standards.

NR 428.04(2)(a) (a) Boilers.

NR 428.04(2)(a)1. 1. Solid fuel-fired units. No person may cause, allow or permit nitrogen oxides to be emitted from a solid fuel-fired boiler in amounts greater than those specified in this subdivision.

NR 428.04(2)(a)1.a. a. 0.15 pound per million Btu of heat input on a 30-day rolling average basis for boilers with a maximum design heat input of 250 million Btu per hour or greater.

NR 428.04(2)(a)1.b. b. 0.20 pound per million Btu of heat input on a 30-day rolling average basis for boilers with a maximum design heat input of less than 250 million Btu per hour.

NR 428.04(2)(a)2. 2. Gaseous fuel-fired units. No person may cause, allow or permit nitrogen oxides to be emitted from a gaseous fuel-fired boiler with a maximum design heat input of 25 million Btu per hour or greater in an amount greater than 0.05 pound per million Btu of heat input on a 30-day rolling average basis.

NR 428.04(2)(a)3. 3. Distillate fuel oil-fired boilers. No person may cause, allow or permit nitrogen oxides to be emitted from a distillate fuel oil-fired boiler with a maximum design heat input of 25 million Btu per hour or greater in an amount greater than 0.09 pound per million Btu of heat input on a 30-day rolling average basis.

NR 428.04(2)(a)4. 4. Residual fuel oil-fired boilers. No person may cause, allow or permit nitrogen oxides to be emitted from a residual fuel oil-fired boiler with a maximum design heat input of 25 million Btu per hour or greater in an amount greater than 0.15 pound per million Btu of heat input on a 30-day rolling average basis.

NR 428.04(2)(a)5. 5. Kraft recovery boilers. No person may cause, allow or permit nitrogen oxides to be emitted from a kraft recovery boiler with a maximum design heat input of 50 million Btu per hour or greater in an amount greater than 0.10 pound per million Btu of heat input on a 30-day rolling average basis.

NR 428.04(2)(b) (b) Cement kilns, lime kilns and calciners. No person may cause, allow or permit nitrogen oxides to be emitted from a cement kiln, lime kiln or calciner with a maximum design heat input of 50 million Btu per hour or greater in amounts greater than those specified in this paragraph.

NR 428.04(2)(b)1. 1. 0.10 pound per million Btu on a 30-day rolling average basis when burning gaseous fuel.

NR 428.04(2)(b)2. 2. 0.12 pound per million Btu on a 30-day rolling average basis when burning distillate fuel oil.

NR 428.04(2)(b)3. 3. 0.20 pound per million Btu on a 30-day rolling average basis when burning residual fuel oil.

NR 428.04(2)(b)4. 4. 0.60 pound per million Btu on a 30-day rolling average basis when burning solid fuel.

NR 428.04(2)(c) (c) Reheat, annealing and galvanizing furnaces. No person may cause, allow or permit nitrogen oxides to be emitted from a reheat furnace, annealing furnace or galvanizing furnace with a maximum design heat input of 50 million Btu per hour or greater in an amount greater than 0.10 pound per million Btu on a 30-day rolling average basis.

NR 428.04(2)(d) (d) Glass furnaces. No person may cause, allow or permit nitrogen oxides to be emitted from a glass furnace with a maximum design heat input of 50 million Btu per hour or greater in an amount greater than 4.0 pounds per ton of pulled glass on a 30-day rolling average basis.

NR 428.04(2)(e) (e) Asphalt plants. No person may cause, allow or permit nitrogen oxides to be emitted from an asphalt plant with a maximum design heat input of 50 million Btu per hour or greater in amounts greater than those specified in this paragraph.

NR 428.04(2)(e)1. 1. 0.15 pound per million Btu of heat input on a 30-day rolling average basis when burning gaseous fuel.

NR 428.04(2)(e)2. 2. 0.20 pound per million Btu of heat input on a 30-day rolling average basis when burning distillate fuel oil.

NR 428.04(2)(e)3. 3. 0.27 pound per million Btu of heat input on a 30-day rolling average basis when burning residual fuel oil or waste oil.

NR 428.04(2)(f) (f) Process heating units. No person may cause, allow or permit nitrogen oxides to be emitted from a process heater, dryer, oven or other external combustion unit with a maximum design heat input of 50 million Btu per hour or greater in amounts greater than those specified in this paragraph.

NR 428.04(2)(f)1. 1. 0.10 pound per million Btu of heat input on a 30-day rolling average basis when burning gaseous fuel.

NR 428.04(2)(f)2. 2. 0.12 pound per million Btu of heat input on a 30-day rolling average basis when burning distillate fuel oil.

NR 428.04(2)(g) (g) Combustion turbines.

NR 428.04(2)(g)1. 1. Gaseous fuel-fired units. Except as provided in subds. 3. and 4., no person may cause, allow or permit nitrogen oxides to be emitted from a gaseous fuel-fired combustion turbine in amounts greater than those specified in this subdivision.

NR 428.04(2)(g)1.a. a. 12 parts per million dry volume (ppmdv), corrected to 15% oxygen, on a 30-day rolling average basis for a simple cycle combustion turbine with a maximum design power output of 85 MWe or greater.

NR 428.04(2)(g)1.b. b. 9 parts per million dry volume (ppmdv), corrected to 15% oxygen, on a 30-day rolling average basis for a simple cycle combustion turbine with a maximum design power output of 40 MWe or greater but less than 85 MWe.

NR 428.04(2)(g)1.c. c. 25 parts per million dry volume (ppmdv), corrected to 15% oxygen, on a 30-day rolling average basis for a simple cycle combustion turbine with a maximum design power output of less than 40 MWe.

NR 428.04(2)(g)1.d. d. 9 parts per million dry volume (ppmdv), corrected to 15 percent oxygen, on a 30-day rolling average basis for a combined cycle combustion turbine with a maximum design power output of 25 MWe or greater.

NR 428.04(2)(g)1.e. e. 14 parts per million dry volume (ppmdv), corrected to 15% oxygen, on a 30-day rolling average basis for a combined cycle combustion turbine with a maximum design power output of less than 25 MWe.

NR 428.04(2)(g)2. 2. Distillate fuel oil-fired units. No person may cause, allow or permit nitrogen oxides to be emitted from a distillate fuel oil-fired combustion turbine in amounts greater than those specified in this subdivision.

NR 428.04(2)(g)2.a. a. 25 parts per million dry volume (ppmdv), corrected to 15% oxygen, on a 30-day rolling average basis for a simple cycle combustion turbine with a maximum design power output of 85 MWe or greater.

NR 428.04(2)(g)2.b. b. 25 parts per million dry volume (ppmdv), corrected to 15% oxygen, on a 30-day rolling average basis for a simple cycle combustion turbine with a maximum design power output of 40 MWe or greater but less than 85 MWe.

NR 428.04(2)(g)2.c. c. 65 parts per million dry volume (ppmdv), corrected to 15% oxygen, on a 30-day rolling average basis for a simple cycle combustion turbine with a maximum design power output of less than 40 MWe.

NR 428.04(2)(g)2.d. d. 8 parts per million dry volume (ppmdv), corrected to 15% oxygen, on a 30-day rolling average basis for a combined cycle combustion turbine with a maximum design power output of 25 MWe or greater.

NR 428.04(2)(g)2.e. e. 25 parts per million dry volume (ppmdv), corrected to 15% oxygen, on a 30-day rolling average basis for a combined cycle combustion turbine with a maximum design power output of less than 25 MWe.

NR 428.04(2)(g)3. 3. Units fired by an integrated gasification process. No person may cause, allow or permit nitrogen oxides to be emitted from a combined cycle combustion turbine that is fired by fuel derived from an integrated gasification process in amounts greater than 15 parts per million dry volume (ppmdv), corrected to 15% oxygen, on a 30-day rolling average basis.

NR 428.04(2)(g)4. 4. Units fired by a biologically derived gaseous fuel. No person may cause, allow or permit nitrogen oxides to be emitted from a biologically derived gaseous fuel fired combustion turbine in amounts greater than those specified in this subdivision.

NR 428.04(2)(g)4.a. a. 35 parts per million dry volume (ppmdv), corrected to 15% oxygen, on a 30-day rolling average basis for a simple cycle combustion turbine.

NR 428.04(2)(g)4.b. b. 35 parts per million dry volume (ppmdv), corrected to 15% oxygen, on a 30-day rolling average basis for a combined cycle combustion turbine.

NR 428.04(2)(h) (h) Reciprocating engines. No person may cause, allow or permit nitrogen oxides to be emitted from a reciprocating engine in amounts greater than those specified in this paragraph.

NR 428.04(2)(h)1. 1. 6.9 grams per brake horsepower-hour for a compression ignition unit with a maximum design power output of 1000 hp or greater.

NR 428.04(2)(h)2. 2. 4.0 grams per brake horsepower-hour for a spark ignition unit with a maximum design power output of 1000 hp or greater.

NR 428.04(2)(i) (i) Emissions units using secondary fuel. An emissions unit that is capable of firing secondary fuel is not subject to the requirements under this subsection when utilizing only a secondary fuel if any of the following apply:

NR 428.04(2)(i)1. 1. The emissions unit heat input capacity or maximum design power output while utilizing the secondary fuel is less than the applicability thresholds under this subsection.

NR 428.04(2)(i)2. 2. The emissions unit burns the secondary fuel only during any of the following periods:

NR 428.04(2)(i)2.a. a. Supply interruption or curtailment of primary fuel. The secondary fuel usage under this paragraph may not exceed 500 hours within a 12 consecutive month time period unless the owner or operator obtains a fuel variance under s. NR 436.06.

NR 428.04(2)(i)2.b. b. Periodic testing, maintenance, or operator training of the secondary fuel when the periodic testing, maintenance, or operator training does not exceed a combined total of 48 hours during any calendar year.

NR 428.04(2)(i)3. 3. The secondary fuel constitutes less than 1 percent on an energy equivalent basis of the emissions unit’s fuel consumption within the most recent 12 consecutive month time period.

NR 428.04(3) (3) Monitoring requirements.

NR 428.04(3)(a) (a) General requirements.

NR 428.04(3)(a)1. 1. The owner or operator of each NOx emissions unit subject to the requirements of sub. (2) shall comply with the monitoring requirements of subch. III.

NR 428.04(3)(a)2. 2. The emissions measurements recorded and reported in accordance with subch. III shall be used to determine compliance by the unit with the applicable NOx emissions performance standard under sub. (2).

NR 428.04(3)(b) (b) Specific requirements. The owner or operator of each NOx emissions unit subject to the requirements of sub. (2) shall determine the unit’s average NOx emission rate using methods and procedures specified in 40 CFR part 60, Appendix B, incorporated by reference in s. NR 484.04 (21), or other emissions monitoring methods approved by the department.

NR 428.04(4) (4) Recordkeeping and reporting requirements.

NR 428.04(4)(a) (a) Except as provided in subd. 1., the owner or operator of each NOx emissions unit subject to the requirements of this section shall keep on site at the source each of the following documents for a period of 5 years from the date the document is created.

NR 428.04(4)(a)1. 1. All emissions monitoring information, in accordance with subch. III; except that, to the extent that subch. III provides for a 3-year period for record retention, the 3-year period shall apply.

NR 428.04(4)(a)2. 2. Copies of all reports, compliance certifications and other submissions and all records made or required under the NOx emissions performance program.

NR 428.04(4)(b) (b) The owner or operator of the NOx emissions source shall submit the compliance reports and certifications required under the NOx emissions performance program in conjunction with those required under the construction permit requirements of ch. NR 406 and the operation permit requirements of s. NR 407.09.