(a) Except as provided for in paragraph (c) of this section, for each stationary combustion turbine you must not discharge into the atmosphere from the affected facility any gases that contain an amount of NOX that exceeds the applicable emissions standard and be in accordance with the requirements specified in paragraph (b) of this section. If you choose to use NOX CEMS, input-based emission rates and standards are determined on a 4-operating-hour rolling basis and output-based emission rates and standards are determined on a 30-operating-day rolling basis. Mass-based emission rates are determined on both a 4-operating-hour and 12-calendar-month rolling basis.
(b) For the purpose of determining compliance with the applicable emissions standard, you must also meet the requirements specified in paragraphs (b)(1) through (4) of this section, as applicable to your affected facility.
(1) The NOX emission standard that is applicable to your affected facility shall be determined on an operating-hour basis, unless you elect to use the alternative provided for in paragraph (b)(2) of this section. Determining the hourly NOX emission standards for your affected facility requires recording hourly data and maintaining records according to the requirements in § 60.4390a. For hours with multiple emission standards, the applicable standard for that hour is determined based on the condition, excluding periods of monitor downtime, that corresponds to the highest emissions standard. For example, if your affected facility operates at 70 percent or less of its base load rating for any portion of the hour, the emission limit(s) in table 1 to this subpart for combustion turbines operating at 70 percent or less of base load rating shall apply for that hour.
(2) As an alternative to the requirements specified in paragraph (b)(1) of this section, you may elect to use the lowest NOX emission standard that is applicable to your affected facility, as determined using table 1 to this subpart, for the entire required compliance period.
(3) During each operating hour when only natural gas is combusted, you must meet the NOX emission standard as determined by the applicable size category in table 1 or 2 to this subpart, as applicable, which corresponds to a stationary combustion turbine firing natural gas for that operating hour. During each operating hour when the heat input (based on the HHV of the fuels) of the combustion turbine engine is less than 50 percent natural gas (i.e., 50 percent or greater non-natural gas), as defined in § 60.4420a, at any point during an operating hour, you must meet the NOX emission standard as determined by the applicable size category in table 1 or 2 to this subpart, as applicable, which corresponds to a stationary combustion turbine firing fuels other than natural gas for that operating hour. During each operating hour when the heat input to the combustion turbine engine is greater than 50 percent natural gas, as defined in § 60.4420a, during an entire operating hour while combusting some portion of non-natural gas fuels, you must meet the NOX emission standard as determined by prorating the applicable NOX standards, based on the applicable size category in table 1 or 2 to this subpart, as applicable, by the heat input from each fuel type.
(4) If you have two or more combustion turbine engines share a common stack, are connected to a single electric generator, or share a steam turbine, except as provided for in paragraph (b)(4)(i) of this section, you must monitor the hourly NOX emissions at the common stack in lieu of monitoring each combustion turbine separately. If you choose to comply with the output-based emissions standard, the hourly gross or net energy output (electric, thermal, or mechanical, as applicable) must be the sum of the hourly loads for the individual affected combustion turbines, and you must express the operating time as “stack operating hours” (as defined in 40 CFR 72.2). If you attain compliance with the most stringent applicable emission standard in table 1 or 2 to this subpart, as applicable, at the common stack, each affected combustion turbine sharing the stack is in compliance.
(i) As an alternative to the requirements in this paragraph (b)(4), you may either:
(A) Monitor each combustion turbine separately by measuring the NOX emissions prior to mixing in the common stack; or
(B) Apportion the NOX emissions based on the unit's heat input contribution to the total heat input associated with the common stack and the appropriate F-factors. If you chose to comply with the output-based standard, output from a common steam turbine shall be apportioned based on the heat input to each combustion turbine. You may also elect to develop, demonstrate, and provide information satisfactory to the Administrator on alternate methods to apportion the NOX emissions. The Administrator may approve such alternate methods for apportioning the NOX emissions whenever the demonstration ensures accurate estimation of emissions regulated under this part.
(ii) [Reserved]
(c) Stationary combustion turbines that meet at least one of the specifications described in paragraphs (c)(1) through (4) of this section are exempt from the applicable NOX emission standard in paragraphs (a) and (b) of this section.
(1) An emergency combustion turbine, as defined in § 60.4420a;
(2) A stationary combustion turbine that, as determined by the Administrator or delegated authority, is used for the research and development of control techniques and/or efficiency improvements relevant to stationary combustion turbine emissions; or
(3) A stationary combustion turbine that combusts byproduct fuels for which a facility-specific NOX emissions standard has been established by the Administrator or delegated authority according to the requirements of paragraphs (c)(3)(i) and (ii) of this section is exempt from the emission limits specified in tables 1 and 2 to this subpart.
(i) You may request a facility-specific NOX emission standard by submitting a written request to the Administrator or delegated authority explaining why your affected facility, when combusting the byproduct fuel, is unable to comply with the applicable NOX emission standard determined using table 1 or 2 to this subpart.
(ii) If the Administrator or delegated authority approves the request, a facility-specific NOX emissions standard will be established in a manner that the Administrator or delegated authority determines to be consistent with minimizing NOX emissions.
(4) Military combustion turbines for use in other than a garrison facility and military combustion turbines installed for use as military training facilities.
(d) You must meet the applicable NOX emissions standard to your affected facility during all times that the affected facility is operating (including periods of startup, shutdown, and malfunction).
