(a) Totalizing fuel flow meters.
  (1) The owner or operator of units subject to this division shall install, calibrate, maintain, and operate a totalizing fuel flow meter, with an accuracy of ± 5%, to individually and continuously measure the gas and liquid fuel usage. A computer that collects, sums, and stores electronic data from continuous fuel flow meters is an acceptable totalizer. The owner or operator must continuously operate the totalizing fuel flow meter at least 95% of the time when the unit is operating during a calendar year. For the purpose of compliance with this subsection for units having pilot fuel supplied by a separate fuel system or from an unmonitored portion of the same fuel system, the fuel flow to pilots may be calculated using the manufacturer's design flow rates rather than measured with a fuel flow meter. The calculated pilot fuel flow rate must be added to the monitored fuel flow when fuel flow is totaled.
  (2) The following are alternatives to the fuel flow monitoring requirements of this subsection.
    (A) Units operating with a nitrogen oxides (NOX ) and diluent continuous emissions monitoring system (CEMS) under subsection (c) of this section may monitor stack exhaust flow using the flow monitoring specifications of 40 Code of Federal Regulations (CFR) Part 60, Appendix B, Performance Specification 6 or 40 CFR Part 75, Appendix A.
    (B) Units that vent to a common stack with a NOX and diluent CEMS under subsection (c) of this section may use a single totalizing fuel flow meter.
    (C) Gas-fired lean-burn stationary reciprocating internal combustion engines and gas turbines equipped with a continuous monitoring system that continuously monitors horsepower and hours of operation are not required to install totalizing fuel flow meters. The continuous monitoring system must be installed, calibrated, maintained, and operated according to manufacturers' recommended procedures.
(b) NOX monitors.
  (1) The owner or operator of the following units shall install, calibrate, maintain, and operate a CEMS or predictive emissions monitoring system (PEMS) to monitor exhaust NOX :
    (A) units with a rated heat input greater than or equal to 100 million British thermal units (MMBtu) per hour;
    (B) stationary gas turbines with a megawatt (MW) rating greater than or equal to 30 MW and operated more than 850 hours per year;
    (C) units that use a chemical reagent for reduction of NOX ; and
    (D) units that the owner or operator elects to comply with the NOX emission specifications of §117.205(a) of this title (relating to Emission Specifications for Reasonably Available Control Technology (RACT)) using a pound per MMBtu limit on a 30-day rolling average.
  (2) Units subject to the NOX CEMS requirements of 40 CFR Part 75 are not required to install CEMS or PEMS under this subsection.
  (3) The owner or operator shall use one of the following methods to provide substitute emissions compliance data during periods when the NOX monitor is off-line:
    (A) if the NOX monitor is a CEMS:
      (i) subject to 40 CFR Part 75, use the missing data procedures specified in 40 CFR Part 75, Subpart D (Missing Data Substitution Procedures); or
      (ii) subject to 40 CFR Part 75, Appendix E, use the missing data procedures specified in 40 CFR Part 75, Appendix E, §2.5 (Missing Data Procedures);
    (B) if the NOX monitor is a PEMS:
      (i) use the methods specified in 40 CFR Part 75, Subpart D; or
      (ii) use calculations in accordance with §117.8110(b) of this title (relating to Emission Monitoring System Requirements for Utility Electric Generation Sources);
    (C) monitor operating parameters for each unit in accordance with 40 CFR Part 75, Appendix E, §1.1 or §1.2 and calculate NOX emission rates based on those procedures; or
    (D) use the maximum block one-hour emission rate as measured during the initial demonstration of compliance required in §117.235(e) of this title (relating to Initial Demonstration of Compliance).
(c) CEMS requirements. The owner or operator of any CEMS used to meet a pollutant monitoring requirement of this section shall comply with the requirements of §117.8100(a) of this title (relating to Emission Monitoring System Requirements for Industrial, Commercial, and Institutional Sources).
(d) PEMS requirements. The owner or operator of any PEMS used to meet a pollutant monitoring requirement of this section shall comply with the following.
  (1) The PEMS must predict the pollutant emissions in the units of the applicable emission limitations of this division.
  (2) The PEMS must meet the requirements of §117.8100(b) of this title.
(e) Engine monitoring. The owner or operator of any gas-fired lean-burn stationary reciprocating internal combustion engine subject to the emission specifications of this division shall stack test engine NOX emissions as specified in §117.8140(a) of this title (relating to Emission Monitoring for Engines).
(f) Run time meters. The owner or operator of any stationary gas turbine or gas-fired lean-burn stationary reciprocating internal combustion engine claimed exempt using the exemption of §117.203(1)(D) of this title (relating to Exemptions) shall record the operating time with a non-resettable elapsed run time meter.
(g) Data used for compliance. After the initial demonstration of compliance required by §117.235 of this title, the methods required in this section must be used to determine compliance with the emission specifications of §117.205(a) of this title. For enforcement purposes, the executive director may also use other commission compliance methods to determine whether the unit is in compliance with applicable emission specifications.
(h) Testing requirements.
  (1) The owner or operator of units that are subject to the emission specifications of §117.205(a) of this title shall test the units as specified in §117.235 of this title in accordance with the applicable schedule specified in §117.9010 of this title (relating to Compliance Schedule for Bexar County Eight-Hour Ozone Nonattainment Area Major Sources).
  (2) The owner or operator of any unit not equipped with CEMS or PEMS that are subject to the emission specifications of §117.205(a) of this title shall retest the unit as specified in §117.235 of this title within 60 days after any modification that could reasonably be expected to increase the NOX emission rate.

Source Note: The provisions of this §117.240 adopted to be effective May 16, 2024, 49 TexReg 3347