Document 6KOGGv4VyzBYBp1rXbVGoNaE

TALEN ENERGY NortiNestern EFI('P)Y 2 March 28. 2025 efficiency to increase from 99.6% to 99.8%, which cannot be achieved by wet venturi scrubber technology. Colstrip would be required to install new fabric filters (also known as baghouscs) downstream of the wet venturi scrubbers. This combination is unproven, untested, and raises significant risks to the operation of Colstrip and its ability to timely achieve compliance. For this reason alone, the technology necessary to increase Colstrip's PM control from 99.6% to 99.8% (as required by the 2024 MATS rule) is technologically "unavailable." Moreover, based on recent developments in project schedule and costs, a project to install the baghouscs would cost over $500 million. These costs are uneconomic, and with respect to NorthWestern, may be unrecoverable, or not fully recoverable in electric rates. Given these costs and technological uncertainty, there is danger that Colstrip would retire instead of installing controls that could cause severe operational issues. As a result, the installation of baghouscs is economically "unavailable." Additionally, even if Talen Montana and NorthWestern were to take the risk, there is a significant likelihood that the baghouscs could not be installed and be operational to meet the compliance requirements until early 2029, far past the statutory deadline. These circumstances make the technology "unavailable" from a timing perspective for Colstrip. National security. It would be "in the national security interests of the United States" to provide the requested exemption to Colstrip from the 2024 MATS Rule. Multiple Executive Orders issued by the President have reaffirmed that removing any and all regulatory burdens restricting power plants' operation would advance various national security interests. This is especially the case for Colstrip, a core facility that powers the western part of. the United States and is a major economic driver for Montana. Colstrip is critical to grid reliability and resource adequacy, and disruption of operations or the plant's forced retirement in the face of the 2024 MATS Rule would harm the national security interests of. the United States because replacement power could not be easily procured in the region. As but one example, reserve power margins are already low (10%, and are projected to worsen) in the western parts of the United States--which house numerous military bases, such as the Malmstrom Air Force Base near Great Falls, Montana. An energy emergency already exists in the western United States, as declared by one of the Executive Orders. II. BACKGROUND Section 112 of the CAA regulates ha7ardous air pollutants such as mercury or non-mercury metals. Power plants are subject to Section 112 only if EPA finds it "appropriate and necessary." 42 U.S.C.. 7412(n)(1)(A). These standards undergo a review every eight years. hi. 7412(f). EPA under the first Trump Administration completed this review and determined that changes to Sierra Club FOIA 2025-EPA-04883 ED_018388_00000306-00002 SC_EVERSPLIT0006086