Clean Unit “Comparable to BACT” DeterminationLimitations

摘要

Facility operators in delegated New Source Review (NSR) and State ImplementationPlan (SIP)-approved states who seek Clean Unit status but have not received a majorNSR permit within the last 10 years, or those who wish to requalify for Clean Unit status,can do so by completing a “comparable-to-BACT” analysis. An emissions unit is“comparable-to-BACT” if it achieves an emission limit that is equal to or better than theaverage of the limits achieved by similar sources for which a BACT determination wasmade in the last five years and is listed in the U.S. Environmental Protection Agency’s(EPA’s) RACT/BACT/LAER Clearinghouse (RBLC). This approach seemsstraightforward, but can yield misleading results without additional research of theemission limits listed in the RBLC.A recent permitting project involving a coal-fired boiler illustrates the details that must beevaluated when conducting a “comparable-to-BACT” analysis. The facility operatorcompleted a “comparable-to-BACT” analysis for PM10 emissions using the methodspecified in the rule. However, the preliminary findings of this analysis were incomplete.The RBLC does not include the test methods on which the emission limits are based.Until recently, many construction permits for coal-fired boilers did not require theinclusion of condensible PM in the total PM10 emission limits. The condensible fractionof PM10 can significantly contribute to the total PM10. Further, many projects have beenpermitted but not tested and therefore did not meet the “demonstrated to be achieved”criteria of the rule. Test methods can have a significant effect on the emission limit. Itwas determined that the original “comparable-to-BACT” test methods included severalemission limits that were based on different test methods than that proposed by thefacility; therefore, not all the units qualify as “comparable” units for the purpose of theClean Unit determination test.This paper uses a Clean Unit project as a case study to illustrate the limitations ofcompleting a “comparable-to-BACT” determination using only information from theRBLC.