On May 25th, EPA published in the Federal Register an interpretative rule that clarifies the Agencys position with respect to the requirements of Sections 112(g) and 112(j) of the Clean Air Act. This Federal Register notice also formally withdraws the interpretative rule that was erroneously published on April 21st. The bottom line of the interpretative rule appears to be that EPA considers the term "electric utility steam generating unit" to mean those things that we typically call boilers, when the steam is expanded through a turbine to spin a generator. Since combustion turbines are not boilers, they must not be "electric utility steam generating units." However, if you hang a heat recovery steam generator (HRSG) behind the combustion turbine and use that steam to make electricity, then youve have both a combustion turbine and an electric utility steam generating unit.
This interpretative rule does address a couple of substantive issues. First, the rule is prospective and becomes "legally effective and binding on June 26, 2000." Second, since combustion turbines are not electric utility steam generating units, the interpretative rule states that case-by-case MACT determinations are required for all new or reconstructed combustion turbines that satisfy the definition of a major stationary source. A copy of this interpretative rule can be downloaded from our FTP Library.
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