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Last week, RMB obtained a copy of EPA's final NSPS Subpart KKKK rule (aka the "Quad K" rule). Subpart KKKK will be effective upon publication of the final rule in the Federal Register, which is anticipated to occur in the next month. The rule will affect all turbines that commence construction, are modified, or are reconstructed after February 18, 2005. Sources subject to Subpart KKKK will not be subject to NSPS Subpart GG, which only affects units constructed prior to the "Quad K" date.

The emission standards in the "Quad K" rule reflect changes in nitrogen oxides (NO_X) emission control technologies and turbine design, since the standards in Subpart GG have remained relatively unchanged since 1977. The "Quad K" emission standards allow the turbine owner or operator the choice of a concentration-based (in units of NO_X ppm @ 15% O₂) or output-based standard (in units of NO_X lb/MWh). These emission standards will vary based upon the size, fuel, application, and location of the affected source.

Similar to that of the revised NSPS Subpart GG rule that was updated in 2004, the Subpart KKKK rule intends to harmonize, where applicable, the Part 60 and Part 75 monitoring and quality assurance requirements for sources that are required to install and operate NO_X CEMS. This harmonization is welcomed by the utility industry, in that the inconsistency and confusion associated with meeting both the Part 60 and Part 75 requirements can now be avoided (where Part 75 takes precedence).

The Subpart KKKK rule, however, is not without its flaws. For example, consider a new combined-cycle 170 MW unit with a Subpart KKKK emission limit of 15 ppm NO_X @ 15% O₂ while firing gas (0.43 lb/MWh) and 42 ppm NO_X @ 15% O₂ while firing oil (1.3 lb/MWh), to be determined on a 30-day rolling average. These standards, in general, should be easily met since a given source's BACT (or LAER) limit will be much lower than the NSPS standard (e.g., a BACT limit of 3.5 ppm NO_X @ 15% O₂). However, the Subpart KKKK rule will also require that the unit's startup, shutdown, and malfunction emissions be included in the 30-day rolling average. For a unit that averages 6 hours of startup and shutdown time per day and 18 hours of controlled operation for the remainder of that 24-hour period, the 30-day rolling average will probably be met. However, for a unit that averages more than 6 hours of startup and shutdown time per day (coupled with less than 18 hours of controlled operation for that day), difficulty meeting the standard could be possible. This will especially be true for cold or cold/cold startup events.

A copy of the final NSPS Subpart KKKK rule is located in our FTP Library. For more information concerning the rule, please contact Robert Bivens at (919) 791-3133.

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Last Revised: January 31, 2007