Document Xv6d8JNnaRZr2RJyXDbvLDVK

that it is in the national security interests of the United States to do so." 42 U.S.C. 7412(i)(4). Accordingly. the President is authorized to exercise his discretion to exempt Oak Grove Units 1 and 2 from complying with the standards set forth in the MATS RTR where (1) the technology required `to implement" the standard is not available and (2) where it is in the interest of national security. In light of this authority. and in light of the burden imposed on electric generating facilities by the MA TS RTR, EPA has announced the potential availability of such exemptions and asked that requests for exemptions he submitted by March 31. See https:iiwww.epa .2ov/stationary-sources-air-poi luti onicl can-ai r-act-section-112-presidentialexemption-information. Consistent with that announcement, and for the reasons set forth below. Oak Grove Management requests a 2-year exemption for Oak Grove from the mercury standard, the fPM standard, and the requirement to implement changes to the CEMS. Section I explains that the technology required to meet the Rule's revised mercury standard is not available. Section II explains that the technology required to implement the Rule's revised fi'M standard is not considered available on a continuous basis and that the related CEMS changes arc likewise unavailable. Section III concludes that it is in the national security interest to issue an exemption from compliance with the MATS RTR. I. The Technology Required for Meeting the Rule's Mercury Standard for Lignite- fired EGUs is Not Available The technology required to continuously meet the revised 1.2 lb/TBtu mercury standard for lignite-fired EGLIs in the MATS RTR does not exist. As explained in Petitioners' merits brief in the case challenging the MATS RTR before the Court of. Appeals for the D.C. Circuit, EPA originally set a mercury standard for lignite-fired EGUs based on the control technology (known as activated carbon injection or "ACI") that was available at the time the mercury standard was first promulgated in 2012. See Pet'rs' Brief at 16-1 7,,Yorth Dakota v. EPA, No. 24-1119, Doc. 2077742 (Oct. 1. 2024). As was recognized in 2012, lignite fired EGUs cannot reliably meet a 1.2 lb/TEitu emission standard for mercury using ACI. See id. This remains the case today. In fact. EPA's own, current data shows that 11 out of 12 lignite facilities have not been able to ever meet the revised standard. Id. at 72. Oak Grove, in particular, would need to achieve a mercury removal efficiency of over 96`.vo with no margin for error to meet the new standard. Comments of Laminant Companies On National Emission .Standards fir Hazardous Air Pollutants: Coal- and Oil-flied Electric Ifuluy .Steam Generating Units Review of the Residual Risk and Technology /?Chew, Docket No. EPA-11Q-OAR-2018-0794-.5983, at 23 (June 23, 2023) [hereinafter "I.uminant Comments"]. But EPA has never demonstrated that the mercury removal efficiency demanded by the Rule is possible. Pet'rs' Brief. at 79. This level of mercury removal is not possible because ACI encounters a "leveling off' effect, at which there are diminishing emissions reductions when increased sorbents are injected to control mercury. Id. at 76. In other words, operators cannot simply "dial-up" the sorbents used in ACI in order to decrease mercury emissions to meet the new standard. And there arc no other control technologies available that can further decrease mercury emissions from lignite-fired EGUs. For this reason alone, Oak Grove should be granted an exemption from compliance with the revised mercury standard in the MATS RTR. In addition to the technological limits to meeting the revised mercury standard, there are also operational limitations associated with the MA TS MR, which make compliance with the standard "not available." For example, EPA's lower mercury standard of 1.2 lbiTritu does not 2 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000159-00002 SC_EVERSPLIT0005926