Wisconsin Administrative Code
Department of Natural Resources
NR 400-499 - Environmental Protection - Air Pollution Control
Chapter NR 446 - Control Of Mercury Emissions
Subchapter III - Fired Electric Generating Units
Section NR 446.18 - Emission determination and compliance demonstration

Universal Citation: WI Admin Code ยง NR 446.18

Current through August 26, 2024

(1) MONITORING REQUIREMENTS. Owners and operators of a coal-fired EGU affected by this subchapter shall monitor emissions, heat input, electricity generation and process thermal energy, as required to demonstrate compliance, according to the following methods and specifications:

(a) For NOx and SO2, hourly mass emissions according to and, Appendices A to I, incorporated by reference in ss. NR 484.03(7) and 484.04(27) respectively.

(b) For mercury, hourly mass emissions using continuous emission monitoring. By December 31, 2013, the department shall promulgate rules that specify the requirements for continuous emission monitoring for purposes of this paragraph.

Note: On February 8, 2008, the U.S. District Court of Appeals for the D.C. Circuit vacated rules the department had intended to rely on related to continuous emission monitoring for mercury emissions. (See New Jersey, et. al. v. Environmental Protection Agency, D.C. Ct. App. No 05-1097, February 8, 2008.)

(c) For heat input flow rate and hourly heat input, according to and, Appendices A to I, incorporated by reference in ss. NR 484.03(7) and 484.04(27) respectively.

(d) For gross electric output, hourly megawatt-hours using continuous monitoring.

(e) For process thermal energy input, hourly mmBtus delivered to the process using continuous monitoring.

(2) DETERMINING ANNUAL ACTUAL EMISSIONS. Owners and operators of a coal-fired EGU affected by this subchapter shall determine annual mass of actual emissions for each pollutant as the sum of monitored emissions according to Equation 1.

where:

Pactual is the mass of mercury, NOx or SO2 emitted during the compliance year

Pmonitored is the mass of mercury, NOx or SO2 emissions monitored and determined for each hour i the EGU is operated during the compliance year

n is the number of hours the EGU is operating during the compliance year

(3) DETERMINING ANNUAL FUEL MERCURY CONTENT. Owners and operators of a coal-fired EGU affected by this subchapter shall determine the annual mass of mercury contained in all combusted fuels, as required to demonstrate compliance, according to the following procedures:

(a) Calculate the mass of mercury contained in each fuel for each month, according to Equation 2, as the mercury concentration in fuel combusted each month as determined following the procedures in s. NR 446.07(1), (2) and (3) according to solid and non-solid types of fuel, multiplied by the amount of fuel, in mmBtu, combusted each month as determined following the procedures in s. NR 446.07(4).

where:

Fuel Hgfm is the mass of mercury contained in fuel f, in month m

HIfm is the heat input of the combusted fuel f, in month m

Hg Cfm is the mercury concentration for fuel f, in month m

(b) Calculate the annual mass of mercury, according to Equation 3, as the sum of mercury contained in all fuels combusted for all months during the compliance year.

where:

Fuel Hgannual is the mass amount of mercury contained in all fuels combusted during the compliance year

Fuel Hgi is the mercury mass content for fuel i, combusted in month m, during the compliance year determined in par. (a)

f is number of fuels combusted during the compliance month

(4) DETERMINING ANNUAL GROSS OUTPUT. Owners and operators of a coal-fired EGU affected by this subchapter shall determine the annual gross energy output in gigawatt-hours, as required to demonstrate compliance, according to the following procedures:

(a) Calculate the annual gross electric output in gigawatt-hours, according to Equation 4, as the sum of gross electric output measured in megawatt-hours for each hour the EGU is operating.

where:

EGWh is the total annual gross electric output in GWh

MWhi is the gross electric output in MWh for each hour i the EGU operated during the compliance year

1,000 is the factor to convert MWh to GWh

n is the number of hours the EGU operated during the compliance year

(b) Calculate the annual amount of useful thermal energy in mmBtu, according to Equation 5, as the sum of the process thermal energy input for each hour the EGU is operated multiplied by the process energy efficiency.

where:

UTEannual is the annual amount of thermal energy, in mmBtu, utilized in the cogeneration process

PTEIi is the amount of thermal energy input, in mmBtu, made available to the cogeneration process for each hour i the EGU operated during the compliance year

PEE is the process energy efficiency, expressed as a percent, measured for the EGU. A value of 50% may be assumed.

n is the number of hours the unit operated during the year of compliance

(c) Calculate the annual gross energy output in mmBtu, according to Equation 6, as the sum of the annual gross electric output and the annual applied thermal energy converted to electric output.

where:

GEOGWh is the total annual gross energy output in GWh

EGWh is the total annual gross electric output in GWh determined in par. (a)

UTEannual is the total annual useful thermal energy in mmBtu determined in par. (b)

3,413 is the factor to convert thermal energy in mmBtu to GWh

(5) DETERMINING ANNUAL ALLOWABLE EMISSIONS. Except as provided in s. NR 446.185, owners and operators of a coal-fired EGU affected by this subchapter shall determine annual allowable emissions, as required to demonstrate compliance, according to the following procedures:

(a) When achieving compliance on a unit-by-unit basis, use one of the following equations as applicable:
1. For a percent reduction mercury emission limitation, Equation 7.

where:

Hgallowable is the mass of mercury emissions allowed for the compliance year

Fuel Hgannual is the mass of mercury in fuel combusted during the compliance year as determined in sub. (3) (b).

Hg CE is the applicable requirement for percent mercury emission reduction divided by 100.

2. For a mercury output emission limitation, Equation 8.

where:

Hgallowable is the mass of mercury emissions in pounds allowed for the compliance year

GEOGWh is the annual gross energy output during the compliance year as determined in sub. (4) (c)

ELoutput is the applicable mercury output based emission limitation in pounds per GWh

3. For an NOx or SO2 emission limitation, Equation 9.

where:

Pallowable is the mass of NOx or SO2 emissions allowed for the compliance year

HIi is the amount of fuel, in mmBtu combusted each hour i, during the compliance year

h is the number of hours fuel is combusted during the compliance year

ELp is the applicable emission limitation of s. NR 446.14(1) for NOx or SO2

(b) When achieving compliance using unit averaging as allowed under s. NR 446.13(2) (b) or 446.14(2) (b), according to Equation 10:

where:

Unit Averaging Pallowable is the mass of mercury, NOx, or SO2 emissions allowed for each pollutant determined in par. (a) for each EGU participating in emissions averaging during the compliance year

Pu is the lowest annual allowable mass of mercury, NOx or SO2 emissions allowed for the compliance year for each EGU as determined under par. (a) or applicable under any other enforceable state or federal requirement for each EGU participating in emissions averaging during the compliance year

n is the number of EGUs participating in emissions averaging

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