Document wKVqRRpmxEZKxQmYy1ZMr9444

r r 0: [ HYPERLINK "mailto:airaction@epa.gov" ] Subject: Presidential Exemption: Section 1 12 of the Clean Air Act : San Miguel Electric Cooperative, Inc. Emission Standards subject to request non-Hg HAP metal surrogate f-PM emission standard for all existing coal-fired EGUs of 0.010 lb/MMBtu. [40 CFR 63.9991(a), Table 2] I Ig emission standard of 1 .2 lb of I Ig per trillion British thermal units of heat input (lb/I-Btu) [40 CFR 63.9991(a), 'Fable 2] Facility Name San Miguel Electric Cooperative, Inc. in Christine, IX Length of compliance period 2 years Justification -- Why the Technoloz. to Implement the Standard is Unavailable The proposed Hg emission limit of 1.2 lb/Tlitu is not technically achievable. San Miguel has an average mercury inlet concentration on 34 lb/TBtu based on the average concentration since 201 1. This is due to the highly variable mercury content of Table 1 : Historical Mercury Inlet Concentrations Since 201 1 and Required Removal Rates Calculated Mercury Inlet and Mercury Capture Rates at Full Load Using Lignite Monthly Composite Data from 2011- Present Mercury Inlet (lbfTbtu) Capture Percentage Required to Reach Target of 1.2 lbfTbtu 22.8 (minimum) 94.7% 34.0 (average) 96.3% 69.4 (maximum) 98.3% A 2013 technical report prepared by Sargent & Lundy that was prepared for EPA analyzed mercury controls (the "S&L Report"). The report describes in detail how activated carbon injection is rendered significantly less effective when the flue gas contains SO3, stating: Some flue gas constituents, especially S03, reduce the mercury removal effectiveness of both activated carbon and non-carbon sorhents. With flue gas .S03 concentrations greater than 5 7 ppmy, the sorhentfeed rate may he increased significantly to meet a high Hg removal and 90% or greater mercury rerno may not heftasible in some cases. Based on commercial testing, the capacity ofactivated carbon can he cut by as much as onehalf with an SO3 increasefrom just 5 pinny to 10 ppmv. Sierra Club FOIA 2025-EPA-04883 ED_018388_00000340-00001 SC_EVERSPLIT0025040 The higher sulfur content of lignite equates to greater production rates of SO3. Texas lignite units often have high flue gas SO3 concentrations and could be considered medium- to high-sulfur coals based on pounds of SO, produced per million Btu of heat input. Gulf Coast lignite generally features higher sulfur content - by a factor of two or more. Notably, Texas lignite is disadvantaged as the alkalinity to sulfur ratio is half that of Powder River Basin Coal (PRB). As to San Miguel, since 2017, the sulfur percentage of the lignite fuel ranges from a minimum of 1 .31 % to a maximum of 3.42%. The lignite fuel used at San Miguel during that time period had an average of 2.48% sulfur content. Based on a fuel analysis conducted in 2014, San Miguel has an average sulfur content of 9.6 lb/SO2 per million Btu. Lignite presents significantly greater variability in Hg and sulfur than PRB. Consequently, the higher sulfur content of lignite combined with equal or lower total alkali relative to sulfur allows measurable levels of SO3 in the lignite-generated flue gas. EPA has not demonstrated any technical developments since the issuances of the previous MATS requirements. The 2020 Final Rule did not discover any developments in control technologies, practices, or processes. In 2023 as to the fPM emission standard, the Proposed Rule concurs. It states that EPA found "no new practices, processes, or control technologies for nonHg HAP." (88 Fed. Reg. 24868). Yet, EPA identifies IPM "developments" to justify an emissions change based on reporting fPM emissions levels and lower costs than originally assumed. Similarly, for fig, in 2023, EPA identities new "developments" for lignite ECiLls based on the operator's compliance with the regulations. In the Proposed Rule, EPA provides no new control technologies or methods. For both pollutants, EPA finds "developments" based on control performance (lower emissions data). It appears that because operators have been diligent in reducing emissions and have been able to achieve the standards set by EPA, EPA feels the need to again tighten the applicable standards. In sum, EPA has found that the current MATS requirements provide an ample margin of safety and has identified no new control technologies or methods. The proposed fPNI emission limit of 0.010 lb/NINIBtu is not technically achievable. Particulate at San Miguel is captured and removed from the flue gas path primarily by the existing electrostatic precipitators ("ESPs"). The wet flue gas desulfuri7ation ("WFGD") system downstream of the ESPs will also capture some of the particulate that makes it through the ESPs. The effectiveness of the existing ESPs and WI2GD system to control PM emissions is demonstrated by the data in Table 2. San Miguel works extremely hard to maintain compliance with this standard. Compliance with the proposed fPM emission limit of 0.010 lb/MMBtu will be marginal under even the best operating scenarios. Sierra Club FOIA 2025-EPA-04883 ED_018388_00000340-00002 SC_EVERSPLIT0025041 Table 2: Summary of Filterable Particulate Matter (fPM) Quarterly Emissions Since 2016 min 5th percentile average 95th percentile max Measured fPM 0.03 lb/MMBtu current limit 0.00600 0.00614 0.03266 0. 1641 1 0.23300 Margin with Proposed Limit (lb/MMBtu) 0.00400 0.00386 -0.02266 -0. 1541 1 -0.22300 Percent Margin ("ri) 40.0% 38.6% -226.6% -1541. 1% -2231).1)';4 Justification -- Why an Extension is in the National Security Interests of the United States San Miguel is a 400 MV', mine-mouth, lignite-fired ECU located in Atascosa County, Texas. San Miguel is a not-for-profit electric cooperative created on February 17. 1977. under the Rural Electric Cooperatil, e Act of the State of I'exas. One hundred percent of the output of the plant is sold to San Miguel's member rural electric cooperatives through the South Texas Electric Cooperative ("STFC"). The electricity that San Miguel produces powers approximately 200,000 rural Texas homes in 45 South Texas counties. San Miguel has conducted a thorough review of the capital and O&M costs that it will be required to take in order to comply with the Proposed Rule. The data provided below in Table 3. Table 3: Summary of Capital and O&M Costs High Estimate Option New Mercury Controls New Baghouse New Particulate CEMS Low Estimate Option New Mercury Controls New Baghouse New Particulate CEMS Capital (2024$) 510,800,000 S160,000,000 $1,950,000 O&M (2024$) $12,745,000 $4,220,000 S25,000 NPV (2024$) $213,493,000 8209,671,000 S2,133,000 Total Levelized Cost $/yr (2024$) 821,126,000 S20,747,000 $211,000 Capital (2024$) S8,100, 000 $130,000,000 81,450,000 O&M (2024$) $10,631,000 $3,430,000 $25,000 NPV (2024$) $177,277,000 S170,378,000 $1,688,000 Total Levelized Cost $/yr (2024$) $17,542,000 $16,859,000 $167,000 The annual operating and maintenance cost of the mercury control system is estimated at approximately S 10,631,000 - $12,745,000, or about $10,000/1b Hg removed. To achieve compliance with the proposed 0.01 lb/MMBtu limit, San Miguel may consider several options including: 1) ESP upgrades, 2) full fabric filter downstream, 3) reduced size fabric filter downstream, and 4) an ESP to fabric filter conversion. Capital costs for the ESP upgrades are projected in the 520 M range. However, there is no way to know with any certainty Sierra Club FOIA 2025-EPA-04883 ED_018388_00000340-00003 SC_EVERSPLIT0025042 if the ESP upgrades will be able to achieve compliance with the proposed fl3M limit of 0.01 lb/MM13tu on a continuous basis. As such, an ESP upgrade is considered technically not feasible. A full-size baghouse installation in the $130 M to 5160 M range. The reduced size baghouse would fall around 10 to 20 percent lower in total installed cost (S9S M - S145 M). The ESP to fabric filter conversion would fall around 20 to 40 percent lower cost (580 M - S 130 M) than the full-size fabric filter and would require a 3 to 4-month unit outage. A cost increase of $35M to $45M annually would require rate payers to spend an extra 33% for their electricity. Because of this sharp increase in expense, it may not be feasible to operate the power plant. SMEC would have to consider securing generation from other sources. The ERCOT grid, which distributes the power generated at SMEC, will likely lose a key dispatchable asset in their portfolio. While renewable sources of energy continue to generate more power for the grid, their lack of dependability to generate at anytime, especially during periods of inclement weather, presents an ominous concern to the public. Providing low-cost, dependable, and dispatchable sources of energy is vital to our national security interests, public health, and strength of our economy. Sierra Club FOIA 2025-EPA-04883 ED_018388_00000340-00004 SC_EVERSPLIT0025043