Document zXQ7xee80jKGQ71E80vEY08g

Message From: Burris, Dave W. [dburris@smeci.net] Sent: 3/28/2025 1:23:46 PM To: AirAction [AirAction@epa.gov] Subject: Presidential Exemption: Section 112 of the Clean Air Act: San Miguel Electric Cooperative, Inc. Attachments:SMEC Clean Air Act Exemption Request.docx Caution: This email originated from outside EPA, please exercise additional caution when deciding whether to open attachments or click on provided links. Flag: Follow up Emission Standards subject to request non-Hg HAP metal surrogate IPM 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/TBtu) 63.9991(a), 'Fable 2] Facility Name San Miguel Electric Cooperative, Inc. in Christine, 'IA Length of compliance period 2 years Justification -- Why the Technology to Implement the Standard is Unavailable [40 CFR The proposed Hg emission limit of 1.2 lb/TBtu 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 lignite. 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% Sierra Club FOIA 2025-EPA-04883 ED_018388_00000339-00001 SC_EVERSPLIT0025036 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: ,S'omellue gas. constituents., especially .5'0.3, reduce the mercury removal fectiyeness of both activated carbon and non-carbon .vorhents. With flue gas. S03 concentration.s greater than 5 7ppmv, the sorhentfeed rate may he increased significantly to meet a high removal and 90% or greater mercury removal may not hefeasible in some cases. Based on commercial testing, the capacity of activated carbon can he cut by as much as one-half with an .5'0.3 increase from just 5 ppmy to 10 ppmy. 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/SO, per million Btu. Lignite presents significantly greater variability in I Ig 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. 'Ihe 2020 Final Rule did not discover any developments in control technologies, practices, or processes. In 2023 as to the f-PM emission standard, the Proposed Rule concurs. It states that EPA found "no new practices, processes, or control technologies for non-I I2 I (88 Fed. Reg. 24868). Yet, EPA identifies fPM "developments" to justify an emissions change based on reporting fPM emissions levels and lower costs than originally assumed. Similarly, for Hg, in 2023, EPA identifies new "developments" for lignite EGlis 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 fi nds "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 fPM emission limit of 0.010 lb/MMBtu 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 dcsulfurization ("WEGD") 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 WFCill 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_00000339-00002 SC_EVERSPLIT0025037 Table 2: Summary of Filterable Particulate Matter (fPM) Quarterly Emissions Since 2016 Measi fPM Ib1MMBtu urn Justification -- Why an Extension is in the National Security Interests of the United States San Miguel is a 400 MW, mine-mouth, lignite-fired ECili located in .Atascosa County, Texas. San Miguel is a not-for-prolit electric cooperative created on February 17, 1977. under the Rural Electric Cooperative Act of the State of Texas. 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 Fexas homes in 45 South Fexas 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 GEMS Capital (2024$) $10,800,000 S160,000,000 $1,950,000 O&M (2024$) $12,745,000 $4,220,000 S25,000 Low Estimate Option New Mercury Controls New Baghouse New Particulate GEMS Capital (2024$) $8,100,000 $130,000,000 $1,450,000 O&M (2024$) $10,631,000 53,430,000 $25,000 NPV (2024$) $213,493,000 S209,671,000 $2,133,000 Total Levelized Cost $iyr (2024$) $21,126,000 $20,747,000 S211,000 NPV (2024$) $177,277,000 5170,378,000 $1,688,000 Total Levelized Cost $iyr (2024$) $17,542,000 $16,859,000 $167,000 The annual operating and maintenance cost of the mercury control system is estimated at approximately 510,631,000 - $12,745,000, or about S10,000/1b fig removed. To achieve compliance with the proposed 0.01 lb/MMFitu 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 arc projected in the 520 M range. However, there is no way to know with any certainty if the ESP upgrades will be able to achieve compliance with the proposed fPM limit of 0.01 lb/MMFitu 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 - $ 130 M) than the full-size fabric filter and would require a 3 to 4month 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. Sierra Club FOIA 2025-EPA-04883 ED_018388_00000339-00003 SC_EVERSPLIT0025038 The ERCOT grid, which distributes the power generated at SMEC, will likely lose a key dispatchablc 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. David Burris, PE Fuels and Environemntal Manager San Miguel Electric Cooperative, Inc. Office - (830) 784-341 1 Ext. 204 Cell - (210) 725-3159 Email - (Thum:, O,OAllaf UNE 00,0041 Dirt Burners Sierra Club FOIA 2025-EPA-04883 ED_018388_00000339-00004 SC_EVERSPLIT0025039