§  75.71 Specific provisions for monitoring NOX emission rate and heat input for the purpose of calculating NOX mass emissions.

(a) Coal-fired units. The owner or operator of a coal-fired affected unit shall either:

(1) Meet the general operating requirements in §  75.10 for a NOX-diluent continuous emission monitoring system (consisting of a NOX pollutant concentration monitor, an O2- or CO2-diluent gas monitor, and a data acquisition and handling system) to measure NOX emission rate and for a flow monitoring system and an O2- or CO2-diluent gas monitor to measure heat input, except as provided in accordance with subpart E of this part; or

(2) Meet the general operating requirements in §  75.10 for a NOX concentration monitoring system (consisting of a NOX pollutant concentration monitor and a data acquisition and handling system) to measure NOX concentration and for a flow monitoring system. In addition, if heat input is required to be reported under the applicable State or federal NOX mass emission reduction program that adopts the requirements of this subpart, the owner or operator also must meet the general operating requirements for a flow monitoring system and an O2- or CO2-diluent gas monitor to measure heat input, or, if applicable, use the procedures in appendix D to this part. These requirements must be met, except as provided in accordance with subpart E of this part.

(b) Moisture correction. (1) If a correction for the stack gas moisture content is needed to properly calculate the NOX emission rate in lb/mmBtu (i.e., if the NOX pollutant concentration monitor in a NOX-diluent monitoring system measures on a different moisture basis from the diluent monitor), the owner or operator of an affected unit shall account for the moisture content of the flue gas on a continuous basis in accordance with §  75.12(b).

(2) If a correction for the stack gas moisture content is needed to properly calculate NOX mass emissions in tons, in the case where a NOX concentration monitoring system which measures on a dry basis is used with a flow rate monitor to determine NOX mass emissions, the owner or operator of an affected unit shall account for the moisture content of the flue gas on a continuous basis in accordance with §  75.11(b) except that the term "SO2" shall be replaced by the term "NOX."

(3) If a correction for the stack gas moisture content is needed to properly calculate NOX mass emissions, in the case where a diluent monitor that measures on a dry basis is used with a flow rate monitor to determine heat input, which is then multiplied by the NOX emission rate, the owner or operator shall install, operate, maintain and quality assure a continuous moisture monitoring system, as described in §  75.11(b).

(c) Gas-fired nonpeaking units or oil-fired nonpeaking units. The owner or operator of an affected unit that, based on information submitted by the designated representative in the monitoring plan, qualifies as a gas-fired or oil-fired unit but not as a peaking unit, as defined in §  72.2 of this chapter, shall either:

(1) Meet the requirements of paragraph (a) of this section and, if applicable, paragraph (b) of this section; or

(2) Meet the general operating requirements in §  75.10 for a NOX-diluent continuous emission monitoring system, except as provided in accordance with subpart E of this part, and use the procedures specified in appendix D to this part for determining hourly heat input. However, the heat input apportionment provisions in section 2.1.2 of appendix D to this part shall not be used to meet the NOX mass reporting provisions of this subpart, except as provided in §  75.72(a); or

(3) Meet the requirements of the low mass emission excepted methodology under paragraph (e)(2) of this section and under §  75.19, if applicable.

(d) Gas-fired or oil-fired peaking units. The owner or operator of an affected unit that qualifies as a peaking unit and as either gas-fired or oil-fired, as defined in §  72.2 of this chapter, based on information submitted by the designated representative in the monitoring plan, shall either:

(1) Meet the requirements of paragraph (c) of this section; or

(2) Use the procedures in appendix D to this part for determining hourly heat input and the procedure specified in appendix E to this part for estimating hourly NOX emission rate. However, the heat input apportionment provisions in section 2.1.2 of appendix D to this part shall not be used to meet the NOX mass reporting provisions of this subpart. In addition, if after certification of an excepted monitoring system under appendix E to this part, the operation of a unit that reports emissions on an annual basis under §  75.74(a) of this part exceeds a capacity factor of 20.0 percent in any calendar year or exceeds an annual capacity factor of 10.0 percent averaged over three years, or the operation of a unit that reports emissions on an ozone season basis under §  75.74(b) of this part exceeds a capacity factor of 20.0 percent in any ozone season or exceeds an ozone season capacity factor of 10.0 percent averaged over three years, the owner or operator shall meet the requirements of paragraph (c) of this section or, if applicable, paragraph (e) of this section by no later than December 31 of the following calendar year.

(e) Low mass emissions units. Notwithstanding the requirements of paragraphs (c) and (d) of this section, the owner or operator of an affected unit that qualifies as a low mass emissions unit under §  75.19(a) shall comply with one of the following:

(1) Meet the applicable requirements specified in paragraphs (c) or (d) of this section; or

(2) Use the low mass emissions excepted methodology in §  75.19(c) for estimating hourly emission rate, hourly heat input, and hourly NOX mass emissions.

(f) Other units. The owner or operator of an affected unit that combusts wood, refuse, or other materials shall comply with the monitoring provisions specified in paragraph (a) of this section and, where applicable, paragraph (b) of this section.

[63 FR 57508, Oct. 27, 1998, as amended at 64 FR 28624, May 26, 1999]