((a)) ** Applicability** On the date that a coal-fired utility unit becomes an affected unit pursuant to sections 7651c, 7651d, 7651h of this title, or on the date a unit subject to the provisions of section 7651c(d) or 7651h(b) of this title, must meet the SO reduction requirements, each such unit shall become an affected unit for purposes of this section and shall be subject to the emission limitations for nitrogen oxides set forth herein.1

((b)) ** Emission limitations**

((1)) Not later than eighteen months after , the Administrator shall by regulation establish annual allowable emission limitations for nitrogen oxides for the types of utility boilers listed below, which limitations shall not exceed the rates listed below: , That the Administrator may set a rate higher than that listed for any type of utility boiler if the Administrator finds that the maximum listed rate for that boiler type cannot be achieved using low NO burner technology. The maximum allowable emission rates are as follows:

((A)) for tangentially fired boilers, 0.45 lb/mmBtu;

((B)) for dry bottom wall-fired boilers (other than units applying cell burner technology), 0.50 lb/mmBtu.

((2)) Not later than , the Administrator shall, by regulation, establish allowable emission limitations on a lb/mmBtu, annual average basis, for nitrogen oxides for the following types of utility boilers:

((A)) wet bottom wall-fired boilers;

((B)) cyclones;

((C)) units applying cell burner technology;

((D)) all other types of utility boilers.

((c)) ** Revised performance standards**

((1))   Not later than , the Administrator shall propose revised standards of performance to for nitrogen oxides emissions from fossil-fuel fired steam generating units, including both electric utility and nonutility units. Not later than , the Administrator shall promulgate such revised standards of performance. Such revised standards of performance shall reflect improvements in methods for the reduction of emissions of oxides of nitrogen.

((d)) ** Alternative emission limitations** The permitting authority shall, upon request of an owner or operator of a unit subject to this section, authorize an emission limitation less stringent than the applicable limitation established under subsection (b)(1) or (b)(2) upon a determination that—

((1)) a unit subject to subsection (b)(1) cannot meet the applicable limitation using low NO burner technology; or

((2)) a unit subject to subsection (b)(2) cannot meet the applicable rate using the technology on which the Administrator based the applicable emission limitation.

((1)) has properly installed appropriate control equipment designed to meet the applicable emission rate;

((2)) has properly operated such equipment for a period of fifteen months (or such other period of time as the Administrator determines through the regulations), and provides operating and monitoring data for such period demonstrating that the unit cannot meet the applicable emission rate; and

((3)) has specified an emission rate that such unit can meet on an annual average basis.

((i)) that permits the unit during the demonstration period referred to in subparagraph (2) above, to emit at a rate in excess of the applicable emission rate;

((ii)) at the conclusion of the demonstration period to revise the operating permit to reflect the alternative emission rate demonstrated in paragraphs (2) and (3) above.

((e)) ** Emissions averaging** In lieu of complying with the applicable emission limitations under subsection (b)(1), (2), or (d), the owner or operator of two or more units subject to one or more of the applicable emission limitations set pursuant to these sections, may petition the permitting authority for alternative contemporaneous annual emission limitations for such units that ensure that (1) the actual annual emission rate in pounds of nitrogen oxides per million Btu averaged over the units in question is a rate that is less than or equal to (2) the Btu-weighted average annual emission rate for the same units if they had been operated, during the same period of time, in compliance with limitations set in accordance with the applicable emission rates set pursuant to subsections (b)(1) and (2).4

If the permitting authority determines, in accordance with regulations issued by the Administrator not later than eighteen months after ;  that the conditions in the paragraph above can be met, the permitting authority shall issue operating permits for such units, in accordance with and part B  of title III, that allow alternative contemporaneous annual emission limitations. Such emission limitations shall only remain in effect while both units continue operation under the conditions specified in their respective operating permits.5section 7651g of this titleNovember 15, 19901990-11-153