Document eaDDqn8dJGaEgw2pzBY0JXjM

,, 'wren MISSOURI March 31, 2025 Honorable Lee Zeldin Office of. the Administrator (1101A) United States Environmental Protection Agency 1200 Pennsylvania Avenue, I.W. Washington, D.C. 20460 airaction(aepa.gov Subject: Docket ID No. EPA-I IQ-OAR-2018-0794 Ameren Missouri Request for a Presidential Exemption Pursuant to CAA Section 1 12(i)(4) for EPA's Final Rule Amending the National Emission Standards for Hazardous Air Pollutants For Coal- And Oil-Fired Electric Utility Steam Generating Units. Facilities: Amercn Missouri Labadie Energy Center Ameren Missouri Sioux Energy Center Dear Administrator Zeldin, Ameren Missouri (Ameren) respectfully requests a two-year Presidential Exemption from compliance with EPA's final rule amending the National Emission Standards for Hazardous Air Pollutants ("NESHAP") for coal- and oil-fired electric utility steam generating units ("EGUs"), commonly referred to as the Mercury and Air Toxics Standards ("MATS") ("Final Rule"), 89 Fed. Reg. 38,508 (May 7, 2024). Ameren requests the compliance exemption extend from July 8, 2027, to July 8, 2029, in accordance with CAA Section 1 12(i)(4). Amcren requests the two-year exemption be granted to all units at both the Ameren Missouri Labadic Energy Center and the Ameren Missouri Sioux Energy Center. That exemption would also avoid forcing Ameren to make commitments to very costly and cost-ineffective control retrofits that will produce little benefits, as EPA reconsiders this rule to determine whether it is consistent with the statutory "necessary and appropriate" standard as interpreted by the Supreme Court in Michigan v. EPA, 576 U.S. 743 (2015). To comply with the Final Rule, Ameren will be required to make additional capital investments which will likely require more time than allotted in the amendments. Achieving compliance with the requirements in the Final Rule by 2027 could jeopardize national security interests by risking the Sierra Club FOIA 2025-EPA-04883 ED_018388_00000111-00001 SC_EVERSPLIT0012440 P;iuc 2 01- .3 reliability of the St. Louis, Missouri electric grid and increasing energy costs for our customers. Granting a two-year compliance exemption will enable Amcren to further evaluate compliance options and limit reliability and consumer pricing impacts, in furtherance of the national security interests announced by the Trump Administration. Achieving compliance with the new MATS requirements by 2027 includes several challenges related to the availability of technology, including: (1) the ability to meet the quality assurance requirements for PM CEMS required by the rule to measure fPM emissions within the criteria required by the Final Rule; (2) the ability to design, to acquire, to install and to commission cost effective control technologies capable of achieving the new MATS fl'M emissions standard; and (3) the ability to do all of this consistent with grid reliability concerns resulting from unit shutdowns necessitated by control installation, which will reduce available generating capacity. During the public commenting process, commenters highlighted significant concerns with the impact of reducing the PM limit on meeting the required Performance Specification 11(PS-11) in Appendix B of 40 CFR Part 60 and Procedure 2 in Appendix B of 40 CFR Part 60 quality assurance testing and correlation requirements at individual units, which is necessary to meet the rules' fundamental requirement to collect, record and submit to EPA continuous quality assured PM CEMS data for each affected unit. Under the MATS rule, every hour that a PM CEMS is unable to provide quality assured data is a violation of the rule. Because the new MATS limits for fPM also reduce the allowable range of acceptable test results necessary for satisfying the criteria for PM quality assurance performance testing defined in PS-1 l, affected units will be out of compliance every time they arc unable to meet the new more restrictive certification requirements. Given the challenges to quality assure PM CEMS, achieving continuous compliance with the MAT's rule monitoring requirements is infeasible without the requested compliance exemption. Ameren has been working with EPRI to develop other continuous monitoring methods to measure non-mercury ha7ardous air pollutant metals directly, such as non-mercury sorbent trap technology, but the technology is still in the process of being developed. In the absence of available technologies to reliably monitor f-PM on a continuous basis, EPA should grant Ameren a two-year compliance exemption to allow development and demonstration of the necessary technology. Ameren also raised concerns about the cost and technical assumptions associated with achieving the new f-PM limit. To comply with the original MATS limits, Ameren installed new state-of-the-art Electrostatic Precipitators (FSPs) on two units in 2014 and 2015. The cost of these retrofits was considerably higher than EPA's cost assumptions used to justify the MATs rule. In addition to the higher costs, the OEM guaranteed emission rate for the new ESPs was higher than the new emissions rate required in the MATs rule. Based on currently available information, Amercn believes it will be difficult to receive a vendor guarantee that can consistently and reliably achieve the new MATS rule requirements. Furthermore, receiving a vendor guarantee that a control device can achieve an emission rate at the emission limit does not guarantee compliance and does not provide compliance margin to allow for operational flexibility. Ameren has been performing a due diligence review to address these issues and to determine an appropriate cost-effective compliance strategy to meet the reduced fPM limit. Those evaluations include, but are not limited to, the following: Sierra Club FOIA 2025-EPA-04883 ED_018388_00000111-00002 SC_EVERSPLIT0012441 Plwe 3 of .3 1. Evaluating Optimization of Existing ESPs, 2. ESP Upgrades and Retrofit Strategies, 3. Alternative PM Control Technologies 4. Control Technology Engineering Cost Estimates, and 5. Control Technology Evaluation Trials. Based on this review, Ameren believes at a minimum that a retrofit of Labadie Units 3 and 4 ESPs will be required, and Sioux Energy Center will require significant ESP maintenance to meet the new MATs f-PM limit. The Labadie Unit 3 and 4 ESP retrofits will include replacing "A" and "3" ESPs with a new "D" ESP. The required time to complete engineering, procurement, construction, outage tie-ins, and performance testing will extend beyond the July 8', 2027, compliance date. Even with the most optimistic timeline, Amercn is uncertain if retrofits can be completed with an additional one-year extension allowed by CAA Section 1 12(i)(3)(b). Given recent supply chain disruptions and the long lead procurement times for critical energy infrastructure equipment, delays in the schedule are likely to occur. Due to the uncertainty, Ameren is requesting the two-year Presidential Exemption. Amercn Missouri has several customers that are critical to the National Security interests of United States. Ameren electric generators provide energy into both Missouri and Illinois markets where several military facilities and critical national defense suppliers are located including Scott Air Base, US Geospatial Institute, Boeing, US Steel, Cerro Copper, and others. Grid reliability is necessary for the uninterrupted operations of these entities which arc paramount to national security considerations. Ensuring that these entities can focus on serving the National Security interests of this nation and not have to deal with electric grid reliability meets the national security requirement of the Presidential Exemption allowance. Ameren Missouri believes that ample justification has been provided to support a decision to grant a two-year Presidential Exemption in accordance with the Clean Air Act for Labadie and Sioux Energy Center. Please contact either Nicholas Bound (618-771-7042) or Michael Hutcheson (314-554-2089) at your convenience if you have any questions regarding this request. Sincerely, Craig J. Gicsmann, P.E.. P.M.P. Sierra Club FOIA 2025-EPA-04883 ED_018388_00000111-00003 SC_EVERSPLIT0012442