Section 217.386  Applicability

a)         Before July 1, 2025, the provisions of this Subpart apply to all:

1)         Stationary reciprocating internal combustion engines listed in Appendix G of this Part.

2)         Stationary reciprocating internal combustion engines and turbines located at a source that emits or has the potential to emit NO_x in an amount equal to or greater than 100 tons per year and is in either the area composed of the Chicago area counties of Cook, DuPage, Kane, Lake, McHenry, and Will, the Townships of Aux Sable and Goose Lake in Grundy County, and the Township of Oswego in Kendall County, or in the area composed of the Metro-East counties of Jersey, Madison, Monroe, and St. Clair, and the Township of Baldwin in Randolph County, where:

A)        The engine at nameplate capacity is rated at equal to or greater than 500 bhp output; or

B)        The turbine is rated at equal to or greater than 3.5 MW (4,694 bhp) output at 14.7 psia, 59°F and 60 percent relative humidity.

b)         On and after July 1, 2025, the provisions of this Subpart apply to all:

1)         Stationary reciprocating internal combustion engines listed in Appendix G of this Part.

2)         Stationary reciprocating internal combustion engines and turbines located at a source that emits or has the potential to emit NO_x in an amount equal to or greater than 50 tons per year and is in either the area composed of the Chicago area counties of Cook, DuPage, Kane, Lake, McHenry, and Will, the Townships of Aux Sable and Goose Lake in Grundy County, and the Township of Oswego in Kendall County, or in the area composed of the Metro-East counties of Madison, Monroe, and St. Clair, where:

A)        The engine at nameplate capacity is rated at equal to or greater than 500 bhp output; or

B)        The turbine is rated at equal to or greater than 3.5 MW (4,694 bhp) output at 14.7 psia, 59°F and 60 percent relative humidity.

c)         Notwithstanding subsections (a)(2) and (b)(2) of this Section, an affected unit is not subject to the requirements of this Subpart Q if the engine or turbine is:

1)         Used as an emergency or standby unit as defined by 35 Ill. Adm. Code 211.1920.  However, the owner or operator of the unit must comply with the recordkeeping requirement under Section 217.396(a)(13);

2)         Used for research or for the purposes of performance verification or testing;

3)         Used to control emissions from landfills, where at least 50 percent of the heat input is gas collected from a landfill;

4)         Used for agricultural purposes, including the raising of crops or livestock that are produced on site, but not for associated businesses like packing operations, sale of equipment or repair; or

5)         An engine with nameplate capacity rated at less than 1,500 bhp (1,118 kW) output, mounted on a chassis or skids, designed to be moveable, and moved to a different source at least once every 12 months.

d)         If an exempt unit ceases to fulfill the criteria specified in subsection (c) of this Section, the unit is subject to the control requirements of this Subpart Q, and the owner or operator must notify the Agency in writing within 30 days after becoming aware that the exemption no longer applies and comply with the control requirements of this Subpart Q.

e)         The requirements of this Subpart Q will continue to apply to any engine or turbine that has ever been subject to the requirements of Section 217.388, even if the affected unit or source ceases to fulfill the rating requirements of subsection (a) or (b) of this Section or becomes eligible for an exemption under subsection (c) of this Section.

f)         Notwithstanding subsection (e), on and after July 1, 2025, the requirements of Subpart Q will continue to apply to any engine or turbine that has ever been subject to the requirements of Section 217.388, even if the affected unit or source ceases to fulfill the requirements of subsection (b) or becomes eligible for an exemption pursuant to subsection (c), except for a combustion turbine that serves a generator that has a nameplate capacity greater than 25 Mwe and produces electricity for sale that does not meet the applicability criteria of subsection (b)(2).

(Source:  Amended at 49 Ill. Reg. 6355, effective April 23, 2025)