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ATTACHMENT A Sierra Club FOIA 2025-EPA-04883 ED_018388_00000327-00013 SC_EVERSPLIT0012794 Minnkota Power COOPERATIVE A Tolic-list(me Ener*' Cooperative jrt,R Minnkota Power Cooperative, Inc. Milton R. Young Station Unis 1 and 2 Mercury Testing Results for the MATS Residual Risk and Technology Review Rev. 2 * May 22, 2024 Project No.: A14559.013 S&L Nuclear QA Program Applicable: _ Yes -X No 55 East Monroe Street Chicago, IL 60603-5780 USA 312-269-2000 www.sargentlundy.corn SEir-gr -rt SA Lundy * Revision 2 corrects the report date exclusively, which was a typographical error in Revision 1. Sierra Club FOIA 2025-EPA-04883 ED_018388_00000327-00014 SC_EVERSPLIT0012795 Minnkota Power Cooperative, Inc. Milton R. Young Station Unit 1 and 2 A14559.013 Rev. 2 May 22, 2024 1 INTRODUCTION 1.1. PURPOSE Sargent & Lundy (S&L) was retained by Minnkota Power Cooperative, Inc. (Minnkota) tosupport the evaluation of mercury (Hg) emissions reductions in response to the pre-published rule to amend the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Coal -and Oil-Fired Electric Utility Steam Generating Units (EGUs), commonly known as Mercury and Air Toxics Standards (MATS) published on April 24, 2023 that would require additional Hg emissions reductions on the Milton R. Young (MRY) Station Unit 1 and 2. As part of this evaluation, S&L assisted Minnkota in the coordination ofa Hg control test campaign to determine if it is feasible to achieve incremental Hg emission reduction on a lignite-fired unit without a fabric filter that is sufficient to meet a 1.2 lb/TBtu Hg emission rate on a continuous basis. 1.2. FACILITY BACKGROUND The MRY station is located approximately seven (7) miles southeast of Center, North Dakota or forty (40) miles northwest of Bismarck, North Dakota on ND Highway 25 at 3401 24th Street SW, Center, North Dakota 58530. MRY station provides energy to the Midcontinent Independent System Operator (MISO) system MRY station consists of two (2) units. Both MRY units are lignite-fired Babcock and Wilcox (B&W) cyclone boilers. Both boilers fire North Dakota lignite coal supplied fromBNl Coal, Ltd.'s Center Mine located in close proximity to the plant. The MRY Unit 1 single wall cyclone boiler (Caroline type, radiant natural circulation ) was placed into service in 1970 and has a typical output capacity rating of 257 MWg (gross). The MRY Unit 2 opposed wall cyclone boiler (Carolina type, radiant pump assisted natural circulation) was placed into service in 1977 and has a typical output capacity rating of470 MWg (gross). Both units utilize selective non-catalytic reduction (SNCR) and separated overfire air (SOFA) systems for NOx control,fuel additive (or halide) injection system and non-halogenated (or non-brominated) powdered activated carbon (PAC) for Hg control,dry electrostatic precipitators (ESP) for PM emissions control, and wet flue gas desulfurization (WFGD) systems for sulfur dioxide (SO2) control. 1.2.1.Current Hg Control System Specifications The existing Hg control system is designed to control Hg emissions below 4.0 IbTTBtu using a combination of M-Prove halide injection and non-halogenated PAC. The M-Prove is directly applied on the coal belt prior to reaching coal silos, whereas the non-halogenated PAC is injected into the duct downstream of the air pre heater (APH). Additional information on the design of the existing fuel additive and PAC injection systems for MRY Units 1 and 2 are summarized below: MRY Common Non-brominated PAC Storage Silo: o PAC Utilized: Cabot DARCO Hg-H non-halogenated PAC o Single storage silo with three (3) outlet cones or discharge connections. Each cone is connected to a feeder train (A, B, and C). o Feeder Train A is dedicated to MRY Unit 1 c Feeder Trains B and C are dedicated to MRY Unit 2 Storage Volume: 4,200 cu.ft. (Nominal) a Capacity: 105,000 lbs. (based on PAC density of 25 lbs/cu.ft.) Mercury Testing Results for the MATS Residual Risk and Technology Review Sargent S. Lundy 1 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000327-00015 SC_EVERSPLIT0012796 Minnkota Power Cooperative, Inc Milton R Young Station Unt 1 and 2 A14559 013 Rev 2 May 22, 2024 Storage duration: Approximately 18 days based on silo capacity of 105,000 lbs and total combined PAC consumption rate of 244 lb/hr (MRY Unit 1 at 86 lb/hr and MRY Unit 2 at 158 lb/hr) MRY Unit 1 (257 MWg) Fuel Additive: ARQ (formerly ADA) M -Prove s Average M-Prove application rate: 6.0 ppm s Maximum M-Prove dosage pump rate: 18.0 ppm Non-brominated PAC Injection: s Maximum Train A PAC injection at 100% feeder rate: 1 43 lb/min (approximately 86 lb/hr or 1.06 lb/MMacf) s Transport piping limited to 192 lb/hr (2.37 lb/MMacf) to avoid pluggage issues s PAC injected into flue gas using eight (8) lances located across the APH outlet duct. s The lance depths vary from 18" -- 54" to provide even distribution of PAC into the flue gas stream MRY Unit 2 (470 MWg) Fuel Additive: ARQ (formerly ADA) M -Prove s Average M-Prove application rate: 8.0 ppm s Maximum M-Prove dosage pump rate: 18.0 ppm Non-brominated PAC Injection: s Maximum Train B and C PAC injection at 100% feeder rate: 2 64 lb/min (approximately 158 Ibihr or 1.12 lb/MMacf) s PAC injected into flue gas using eight (8) lances located across each of the North and South APH outlet ducts for a total of sixteen (16) lances. s The lance depths vary from 15" - 78" to provide even distribution of PAC into the flue gas stream Mercury Testing Results for the MATS Residual Risk and Technology Review Sierra Club FOIA 2025-EPA-04883 2 Si --gr -vt & Lulu/ay ED_018388_00000327-00016 SC_EVERSPLIT0012797 Minnkota Power Cooperative, Inc. Milton R. Young Station Unit 1 and 2 A14559.013 Rev 2 May 22, 2024 2 TEST CAMPAIGN SUMMARY The MRY Units 1 and 2 test campaign was completed in phases to control testing variables and to accommodate vendor availability, and scheduled outages Testing included: November 23, 2023 to November 24, 2023: Maximizing MRY Unit 1 capabilities of the existing MProve fuel additive system and non-halogenated PAC injection (at 100i feeder rate) to evaluate if the current system can meet 1.2 lb/TBtu December 19, 2023 to December 20, 2023: Maximizing MRY Unit 2 capabilities of the existing M Prove fuel additive system and non-halogenated PAC injection (at 100% feeder rate) to evaluate if the current system can meet 1 2 lb/TBtu. March 19, 2024 to March 23, 2024: Utilizing a rental bulk bag unloading (BBU) system provided by Motus Group tied into the existing MRY Unit 1 PAC conveying lines and injection lances to inject brominated PAC (or BPAC), ARQ's FastPAC Platinum", at varied injection rates ranging from 100 lb/hr (or 1.23 lb/MMacf) to a maximum of 185 lb/hr (2.28 lb/MMacf) to stay below the transport piping pluggage limit. The majority of this testing also included maximizing MRY Unit 1 capabilities of the existing M-Prove fuel additive system; however, test runs on March 22 and March 23 included BPAC injection with no fuel additive usage Individual coal samples were taken and analyzed by a 3d party lab for determination of inlet Hg coal content. March 28, 2024 to April 1, 2024: Individual coal samples were taken and analyzed by a 3" party lab for determination of inlet Hg coal content. This testing was not able to be completed during the proposed rule's short comment periodof only 60 days. Due to timing of boiler cleaning outages, time required to develop a test protocol and schedule, and coordination with multiple vendors, rental equipment availability, various site activities, and unplanned unit upsets/outages, a much longer duration was needed 2.1. INCREMENTAL HG REMOVAL TEST RESULTS The Hg emissions achievable based on maximizing current design capabilities using non-brominated PAC and M-Prove without any modifications is summarized below for both MRY Units 1 and 2. Table 2-1 -- MRY Units 1 and 2 Existing System Capabilities Parameter Unit Load during testing PAC Injection Rate Avg. Sorbent Trap Hg Emissions Units MWg lb/MMacf lb/TBtu MRY Unit 1 18 ppm M-Prove and 100% Non-brominated PAC 242 1.06 2.17 MRY Unit 2 18 ppm M-Prove and 100% Non-brominated PAC 469 1.12 1.61 Based on maximizing injection capabilities of the existing systems (without any modifications), the test resu is show that MRY Unit 1 and MRY Unit 2 cannot achieve the proposed MATS limit of 1.2 lb/TBtu. Mercury Testing Results for the MATS Residual Risk and Technology Review Sierra Club FOIA 2025-EPA-04883 Sargent 8 Lundy 3 ED_018388_00000327-00017 SC_EVERSPLIT0012798 Minnkota Power Cooperative, Inc. Milton R. Young Station Unit 1 and 2 A14559.013 Rev. 2 May 22, 2024 2.2. BROMINATED PAC PERFORMANCE The proposed rule assumes a 90% Hg removal Efficiency is feasible from all lignite units, even those equipped with an ESP. In the Beyond-the-Floor memo (Docket ID No. EPA-HQ-OAR-2009-0234), it states that "[g]reater than 90 percent control can be achieved at lignite-fired units at a 2.0 lb/MMacf injection rate for units with installed fabric filter and using treated (i.e., brominated) activated carbon or at an injection rate of 3.0 lb/MMacf for units using treated activated carbon with installed ESPs." According to the proposed MATS rule, EPA reiterates that "[i]n the beyond-the-floor analysis in the final MATS rule, we noted that the results from various demonstration projects suggest that greater than 90 percent Hg control can be achieved at lignitefired units using brominated activated carton sorbent at an injection rate of 2.0 lb/MMacf for units with installed FFs for PM control and at an injection rate of 3.0 lb/MMacf for units with installed ESPs for PM control." The Final Rule relies on the same assumption. In EPA's 2024 Technology Mem orandum, EPA finds, "In the beyond-the-floor analysis in the final MATS rule, we noted that the results from various demonstration projects suggest that greater than 90 percent Hg control can be achieved at lignite fired units using brominated activated carbon sorbent at an injection rate of 2.0 lb/MMacf for units with installed Eric Filters for PM control and at an injection rate of 3.0 lb/MMacf for units with installed ESPs for FM control. . all units (in 2022) would have needed to control their Hgemissions to less than 95 percent to meet an emission standard of 1.2 lb/TBtu. Based on this, we expect that the units could meet the proposed, more stringent, emission standard of 1.2 lb/TBtu by utilizing brominated activated carbon at the injection rates suggested in the beyond-the-floor memorandum from the final MATS rule." During the MRY Unit 1 March testing, MRY secured a temporary rental injection skid . The materials of construction of the existing PAC silo (common to MRY Units 1and 2) is not currently compatible to store halogenated PAC. The silo would require an internal coating to prevent corrosion (but could otherwise be reused). The temporary rental injection skid avoided corrosion to the existing silo, but also allowed for decoupling MRY Unit 1 from the common PAC storage silo to prevent interfering with MRY Unit 2 Hg control operation. To achieve a dosage rate of 3.0 lb/ MMacf, an injection rate of 245 lb/hr would be required which would exceed the existing MRY Unit 1 Train A PAC injection/transport system limit of 192 lb/hr (2.37 lb/MMacf). The maximum BPAC injection rate tested was limited to 185 lb/hr (2.28 lb/MMacf) to avoid line pluggage. The Hg emissions reductions achievable based on maximizing the use of BPAC (without any fuel additives) supplied via a temporary rental injection system tied into the existing transport piping/lances is summarized below for MRY Unit 1. A higher PAC injection rate was not possible due to maximum capability of theexisting transport piping while preventing pluggage. Mercury Testing Results for the MATS Residual Risk and Technology Review Sierra Club FOIA 2025-EPA-04883 Sargent S. Lundy 4 ED_018388_00000327-00018 SC_EVERSPLIT0012799 Minnkota Power Cooperative, Inc Milton R Young Station Unt 1 and 2 A14559 013 Rev 2 May 22, 2024 Table 2-2 -- MRY Unit 1 Existing System Capabilities using Brominated PAC Parameter Unit Load during testing PAC Injection Rate Avg. Sorbent Trap Hg Emissions Units MWg lb/MMact IbrrBtu MRY Unit 1 185 Ibihr BPAC 257 1 2.28 2.57 At the current injection capabilities of the existing system (i.e. requiring minimal modifications/retrofit of the existing equipment), BPAC cannot be applied to reduce Hg emissions to 1 2 lbfTBtu 2.3. MRY MERCURY REMOVAL EFFICIENCY 2.3.1.Lignite Coal Mercury Content To calculate an overall mercury removal efficiency needed to control to 1.2 lb/TBtu, the coal Hg inlet must be defined. EPA reported the "Hg Inlet" level based on the ma ximum Hg content of the range of feedstock coals that the EPA assumes is available to each of the plants in the Integrated Planning Model (IPM) With respect to MRY, EPA reported "Hg inlet": s MRY Units 1 and 2: 7 81 lbfl-Btu According to the proposed rule, EPA estimated the 2021 Hg inlet concentration from actual 2021 fuel usage and 2021 Hg emissions reported to the EPA. However, based on the 2024 Technical Memo, EPA updated the information based on 2022 information With respect to MRY, EPA "Estimated Hg inlet" content documented in 2023 and 2024 Technical Memo is summarized in the table below: Table 2-3 -- EPA Estimated North Dakota Lignite Coal Hg Inlet Parameter MRY Unit 1 MRY Unit 2 Units Ib/TBtu lip/TBtu 2023 Technical Memo (Estimated 2021 Hg Inlet) 7 78 7.79 2024 Technical Memo (Estimated 2022 Hg Inlet) 9 70 9.70 However, recent test information and other resources for the North Dakota lignite fired at MRY has indicated that significantly higher inlet Hg is experienced at MRY: u Within the BNI Coal, Ltd.'s Center Mine, the Kinneman Creek (KC) and Hagel (HA) beds are targeted for the coal supply for MRY. Based on the 2021 BNI coal data (constructed from Carlson reports), the avg. coal Hg content is approximately 16 lbfTBtu for KC and 15 lbfTBtu for HA. The variability of the projected lignite coal quality received from the Center Mine from 2025 through 2036 is shown in the following table Mercury Testing Results for the MATS Residual Risk and Technology Review Si --gr -vt & Lulu/ay 5 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000327-00019 SC_EVERSPLIT0012800 Minnkota Power Cooperative, Inc Milton R Young Station Unt 1 and 2 A14559 013 Rev 2 May 22, 2024 Table 2-4 -- Forecasted 2025 -- 2036 Center Mine Ultimate Coal Analyses (As-Received) Fuel Parameter Mercury Content Higher Heating Value (HHV) Estimated Hg Emission Units ppm Btu/lb Ilp/TBtu ' Average 0.091 6,625 8.41 Minimum Maximum 0.053 0.184 6,489 6,739 4.79 17 42 Industry experience has shown that lignite coal deposits vary significantly in quality, including fuel combustion performance, mineral content, and Hg content, resulting in a coal that can change on a day-to-day basis depending on the coal seam being mined at the time This variability was demonstrated by the range of coal analyses from MRY Unit 1 recent short-term testing in 2024 (average = 10.1 lb/TBtu, with individual results ranging from 4.9 - 18.6 lb/TBtu over the course of five (5) days of testing),Individual coal samples and how they varied across coal feeders, per day are shown in following table. Table 2-5 -- MRY Unit 1 Coal Sampling Analysis Date Sample 19-Mar-24 20-Mar-24 20-Mar-24 21-Mar-24 21-Mar-24 22-Mar-24 22-Mar-24 23-Mar-24 28-Mar-24 1-Apr-24 #1@ 0730 hrs #2@ 1600 hrs #3@ 0100 hrs #1@ 0730 hrs #2@ 1600 hrs #3@ 0100 hrs #1@ 0730 hrs #2@ 1600 hrs #3@ 0100 hrs #1@ 0700 hrs #2@ 1600 hrs #3@ 0100 hrs #1@ 1030 hrs #2@ 1500 hrs #1@ 0930 hrs #2@ 1300 hrs #3@ 1500 hrs Feeder #1 14.5 12.5 6.2 10.9 14.1 7.2 10.4 9.2 10.2 16.3 10.2 Coal Hg Inlet (lb/TBtu) Feeder #3 Feeder #4 Feeder #5 13.0 11.1 8.2 10.5 7 9 7 2 10.1 8 1 7 9 18.6 4.9 7.1 13.4 6.9 11.0 7.8 8 3 14 9 11.9 8 0 6.0 12.1 6 9 Feeder #7 8.0 18.5 7.1 11.4 9.5 12.3 Mercury Testing Results for the MATS Residual Risk and Technology Review Sierra Club FOIA 2025-EPA-04883 Si --gr -vt & Lulu/ay 6 ED_018388_00000327-00020 SC_EVERSPLIT0012801 Minnkota Power Cooperative, Inc. Milton R. Young Station Unit 1 and 2 A14559.013 Rev. 2 May 22, 2024 2.3.2.Required Mercury Removal Based on Lignite Coal Mercury Content Based on the recent Hg fuel analyses, Hg control higher than 90% would actually be required based on the range of inlet coal Hg content expected to control to 1.2 lb/TBtu (i.e. keeping the outlet value calculated by the EPA constant). Note that control to this value does not off er any operating margin for potential exceedances that may occur due to response delays associated with coal variability. The following table identifies the required Hg control needed based on several different coal Hg content references. Based on these estimations, any Hg control approach would need to be able to accommodate a wide range of inlet Hg in order to optimize operating costs long-term. Table 2-6 -- Hypothetical Hg Emissions and Control Performance Based on Coal Analyses Fuel Hg Content Reference EPA Technical Memo 2023 Table 11 Docket ID. No: EPA-HQ-OAR-2019-0794' 2024 Table 10 Docket ID. No; EPA-HQ-OAR-2018-0794" 2024 MRY Unit 1Test Campaign Average Maximum Minimum Center Mine Forecast Average Maximum Minimum Coal Hg Inlet (lb/TBtu) Est. Hg Control at 4.0 lb/TBtu (%) Est Hg Control at 1.2 lb/TBlu (%) 7.81 48.8 84.6 9.70 58.6 87.6 10.1 60.4 88.1 18.6 78.5 93.5 4.9 18.4 75.5 8.41 52.4 85.7 17.42 77.0 93.1 4.79 16.5 75.0 2.3.3.Projected Mercury Removal Based 3.0 IbilIMMacf BPAC Based on the maximum BPAC rate that MRY Unit 1 was able to test due to current system limitations (185 lb/hr or 2.26 lb/MMacf), the figure below plots the estimated percent removal at the higher injection rate of 3.0 lb/MMacf BPAC using all measurements from the MRY Unit 1 March testing (with and without fuel additive usage). The plotted values demonstrate a trend line in which BPAC cannot even achieve 80% Hg removal efficiency. , Benish S. et al. (January 2023). 2023 Technology Review for the Coal- and Oil-Fired EGU Source Category. Environmental Protection Agency. 2 Benish S. et al. (January 2024). 2024 Update to the 2023 Proposed Technology Review for the Coal- and Oil-Fired EGU Source Category. Environmental Protection Agency. Mercury Testing Results for the MATS Residual Risk and Technology Review Sargent S. Lundy 7 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000327-00021 SC_EVERSPLIT0012802 Minnkota Power Cooperative, Inc. Milton R. Young Station Unit 1 and 2 A14559.013 Rev 2 May 22, 2024 Figure 2-1 -- MRY Unit 1 Existing System Mercury Removal Performance Capabilities using Brominated PAC 1000 90 800 1 744 GO G a 11,c 1 .50 140 2 ft. 7 AO 3 0 Proneuted PAC Injection Rate. IbINMact This result is contrary to EPA's assumption that BPAC at a rate of 3.0 lb/MMacf can be used to result in a 90% removal efficiency. The plotted curve shown in the figure shows a leveling off such that increasing the amount of sorbent results in diminishing improvement in Hg control. The projected curve based on the test campaign results shows this leveling off taking place somewhere less than 80% capture. Although the plotted values do not support a conclusion that the new Hg 1.2 lb/TBtu limit can be met, f urther investigation into other Hg control options in combination with upgrading/optimizing existing Hg control equipment would be required to determine the lowest mercury emission rate in lb/TBtu that can be achieved on a long-term basis, considering the range of fuel Hg variabilityand other technological challenges hherent in capturing Hg resulting from lignite that have been documented to occur Some proposed options for additional Hg control include: Increased fuel additive rate Improved reliability of fuel additive concentrationin relation to real-time coal firing rates Implementation of inlet Hg monitor for improved feedback control of Hg control systems Improved lance design to achieve ideal distribution of PAC at all typical unit operating conditions Application of WFGD re-emission control additive Mercury Testing Results for the MATS Residual Risk and Technology Review Sierra Club FOIA 2025-EPA-04883 Sargent 15% Lundy 8 ED_018388_00000327-00022 SC_EVERSPLIT0012803 Minnkota Power Cooperative, Inc. Milton R. Young Station Unit 1 and 2 A14559.013 Rev 2 May 22, 2024 Further analysis, engineering, testing and equipment modifications would be necessary to determine if these options would improve Hg control. However, it is clear that adding morebrominated PAC, as was assumed in the Final Rule, is not adequate, given the properties of lignite, compliance margin necessary, andimitation of mine mouth facilities in regards to fuel staging (i e. must use coal received from mine; unableto fire only certain coals that have a more ideal or predictable range of Hg content during a 30-day rolling average) It should be noted that the achievable Hg emission rate should not be construed to represent an enforceable regulatory or proposed permit limit. Corresponding permit limits must consider normal operaliig fluctuations and coal variability and take into account a minimum additional 20% margin for these fluctuations. Since a combination of new and/or upgraded control systems would be expected to be required, obtaining a guarantee from a single vendor to ensure that the unit achieves compliance below the permit limit will be challenging. Mercury Testing Results for the MATS Residual Risk and Technology Review Sierra Club FOIA 2025-EPA-04883 Sargent S Lundy 9 ED_Ol 8388_00000327-D0023 SC_EVERSPLIT0012804 Minnkota Power Cooperative, Inc Milton R Young Station Unt 1 and 2 A14559 013 Rev 2 May 22, 2024 3.EPA COST VALIDITY 3.1.1.Current Hg Compliance Cost Effectiveness (4.0 lb/TBtu) With respect to MRY, EPA estimated the cost effectiveness forcurrent 2021 Hg emissions is shown below in an excerpt from Table 12 in 2023 Technology Review for the Coal - and OH-Fired EGU Source Category (Docket ID. No: EPA-HQ-OAR-2018- 0794). TABLE. 12 IS-I IMATED COST-EFFECTIVENESS FOR CON FROL O1' MERCURY fN 2021 NI' LIGNITE-IIRED EGUS Plant Name P51 unIrLd 1-151 ulg fflet Ft/ FI , 2021 21/ 50 Ist}IR OW Asg. sm-lerni /1/15/5//5 (16,517/14411 /Lag Sarheni Snrhpnf (-nit S. L1/1 Sr.t.00d ',Lath,: 1 4.1 1 SO S ; (Lida clan' Olds lfdlnn R 6L.,;>1. 1-5N 41 R 4_ - 'a 1 7 7') 6 55 1 53 4' 11 55 11 45 0 50.97 ...21; 50 S5 Vi, 1111 Ma6ff r),1 1.2/01. 5 rr 4 6' 101; 4 19 II SO '55 50.83 Major 16,,r 7 1-F .4 6 5 707 0 SO.R1 Re4 Ft Eh:. Halls I re,-fartg ;16s. 2 4k1 :92" 7.09 2 6 fr 50.76 .4 ir 50.76 1.lar/In r ..rke f 1- Sri- ,I F, :2 L34 r1 i : 0 M 31/ f> S.' Is St , 9^ Oak frr....c ' I-1- : I5.5 154' I - If SI 15 San MIFuel 1 M.Inll, I.,11 2 ]:S14. ,4.f,_ 346 6 " ' 59 5 SO V' 1-501 S 15 ;Li i . i fL 1'1 ' 3 0 '17 0 SO 9' 11.0161 f dkv 1 I tirl " !.. ;', fq % o 1-4 I % 4 . AL11,i.cu..L, ar: ...0Anon f Ill- go. anal. N.., lh, E E:\ a,.rned the ...ILLa...c. COI'A are Cc ,arne annuall,, d, . lloblal sop/5 a. /1.4, 5c lhal Wtry ,,..,,Jed t, the LP A In the 2,):: C A:1 sect.on :14 Ilmorcrw,orl su... , 7.6 0 ihe ,orhent cr,i t. SO 9' F5121321 S6rhent r Fsi 2011 Snrhrni e FA/ 2021 e c 2021 L . L., ff.' "7;62 659 7/./gx /RI 75 9 [72 259 6/0 76' R3 31 Sul I'M iri.: 4 ; s.'50 3.1F0 ...7i4 1 04,5 760 9',65d S7'90,69, / S2h 5 ..Y.q 514-'-RSn71:0 S134 7950 514:,?r,1 51)' . -',4 51)9 7 54 S75,13/ S3in "<7 514, II, !, S465 51K, 5'k'fifiLl 5! .014 ...'2 59.i r.SJ . >.: ', "I S'796 694 . 59, l4 ; S21. 5 ,V19 56,5 6; 5147 :67 R',R44 S``'7 ,41I, C154 26r, S; 046 Si cl5 5145,2h1 5197 296 5199 754 51 'IQ 52 195 s2 ILL $3Lil 'CC Slii -M, 54115 ,,,9 S - 255 660 SI ill 4 m": 5f, 13,J7 5: Mr 5 - 5 01 . Sh.;, ^' . Response: Flaws in EPA's cost analysis for current compliance: Est. Hg In (lb) & Hg Out (lb) o Table 12 would appear to have flipped MRY Unit 1 and Unit 2 in the table, utilizing the higher MRY Unit 2 operating conditions (heat input, hg loading, etc.) for the smaller sized Unit 1 and vice versa PAC Injection Rate: Table 12 Avg. Sorbent (lb/hr) -- EPA noted MRY Unit 1: 19.0 lb/hr and MRY Unit 2: 43.0 lb/hr to achieve controlled Hg rate of 3 2 lbfTBtu Minnkota PAC sorbent injection rates to achieve controlled Hg rate of 3.85 lb/TBtu for MRY Unit 1 is expected to be 86 lb/hr and for MRY Unit 2 is 158 lb/hr. Cost of PAC 0 Table 12 non-brominated PAC sorbent cost-- EPA assumed a cost of $O.8311b. In the 2024 Technical Memo, EPA adjusted this cost down to $0.80/lb Based on MRY operational costs for 2023, non -brominated PAC sorbent cost is $O.86/lb. Based on MRY operational costs for 2023, actual non -brominated PAC costs for achieving current compliance with 4.0 lb/TBtu indicated MRY Unit 1: $119,813 and MAY Unit 2: $329,328 Mercury Testing Results for the MATS Residual Risk and Technology Review Sierra Club FOIA 2025-EPA-04883 10 Si --gr -vt & Lulu/ay ED_018388_00000327-00024 SC_EVERSPLIT0012805 Minnkota Power Cooperative, Inc. Milton R. Young Station Unit 1 and 2 A14559.013 Rev. 2 May 22, 2024 Cost of Fuel Additive: o Table 12 Est. 2021 Additive Cost -- EPA noted that "Additive costs are unknown. For this analysis, the EPA assumed the additive costs are the same, annually, as the sorbent costs." And lists costs as MRY Unit 1: $227,410 and MRY Unit 2: $147,267 o Based on MRY operational costs for 2023, actual fuel additive costs for achieving current compliance with 4.0 Ibiff3tu indicated MRY Unit 1 $715,157 and MRY Unit 2:$1,574,793. o Based on the actual 2023 fuel additive usage r ates and costs, EPA's underestimate results in $487,747 and $1,347,383 that should have been included in the cost analysis for MRY Units 1 and 2, respectively. 3.1.2.Future Hg Compliance Cost Effectiveness (1.2 lb/TBtu) EPA calculated unit-level cost-effectiveness to meet the proposed, more stringent, emissions standard using brominated activated carbon at an injection rate of 5.0 lb/MMacf for units with an ESP for PM control or at an injection rate of 2.5 lb/MMacf for units withfabric filter for PM control. With respect to MRY, the EPA estimated the cost effectiveness (assuming 2021 operational characteristics) is shown below in an excerpt from Table 13 in 2023 Technology Review for the Coal- and Oil-Fired EGU Source Category (Docket ID. No: EPA-HQ-OAR-2018-0794): TABLE 13. ESTIMATED COST-EFFECTIVENESS TO MEET A REVISED MERCURY OF 1.2 LIIITIRTU AT LIGNITE-F1RED EGUS (ASSUMING 2021 OPERATIONAL CHARACTERISICS) YInni Numr 5Jxnlu.nxlN.lxm: I ehowl (Mk I 1chentl 1/Ms I 11.1,1kw R Yourt, 'Halt.R Yews 1 Mayo Oak Knwer I Meye Oak Power 2 PMteeing VI, FSP(' I- SFr: I ISM' I F519 I PI FT 11.44 gigging glieritul WM Mg le PI Ng CI (MI ilr-kti rum (DeMNI4e1) Itii lif-uAsr s.d...i (16) neat non) cite*, . ,... 4.... Sealed midi*. 11i 7 1,) 7.79 779 9 1462 )4A, 1 9I.X 142.2 I501 113.6 20.0 ! pl t 14 II -141 2004 1942 155Y 16.46 91121 4_ 591 191 5.n ieli.:, 1 i $4;.4: 5.1, n95,94.1 tren.1.17 t0 111.751 SM177.nln 10 (0-n ,e, u ill 101 .fg . 2!J.Mt? 111 . 21,..91.0 529 /1431 53:K4.19 55,1X4 11,7n2 $5.691 51.7117 0c 109 11.79 $1.6, 5 OE tells) anemlagg prerico Amulet' mItligive4 511,5X9 19.444 13971 S7 MO SX7fiI S2.114 $2.424 gre Ka, lo,reunk Paulo! 2 0.ik Inn, c I Slatin lac 1 NI (irure 7 Nan Miruel I Marlin Late? Mailin Lake 3 ri 12.41) i. I S1'< R' 14 60 9.21 : M.61 F.SP4" 14.61 I-IP4' X.:1 ESP(' 7.65 109.4 9X110 192.7 /17 ` J46.6 I41.1 37'2.6 1026 110 16 57.16 7155 1.14.-If 1541 5609 3.0 9.e4) $31,0.51b 4.lo . 1.414.4M S1.91.1.40% ,..I. L.160.741 $1., 94.152 10 1.I61,t13 S1.1.4.5,. S.0 T.4,167 SW10.292 . SA, 1.110.919 $1 4 40,55+ 5.0 L .50.1:50 51.703,170 SI 541' n5.452 5.1.6.4" 5" 9X 1.4 .4" 55.647 s3 MC 51.7h 39.2S7 51.126 $4 o '! 1/.2117 Seltl EPA's incremental cost-effectiveness per the 2024 Update to the 2023 Proposed Technology Review for the Coal- and Oil-Fired EGU Source Category (Docket ID. No: EPA-HQ-OAR-2018-0794) is based on a model 800 MW Gulf Coast lignite-fired EGU with a heat rate of 11,000 Btu/kWh operating at an 80% capacity factor and a Hg concentration of 25.0 Ibrifitu resulting in an incremental cost-effectiveness of $28,176 per pound of Hg controlled. It assumes that the unit currently meets a Hg emission standard of 4.0 IbrUBtu using an injection rate of 2.5 lb/MMacf of non-brominated activated carbon at a sorbent cost of $0.80/lb and that the Mercury Testing Results for the MATS Residual Risk and Technology Review Sierra Club FOIA 2025-EPA-04883 11 Sargent a Lundy ED_018388_00000327-00025 SC_EVERSPLIT0012806 Minnkota Power Cooperative, Inc. Milton R. Young Station Unit 1 and 2 A14559.013 Rev. 2 May 22, 2024 unit can meet a Hg emission standard of 1.2 lb/TBtu using an injection rate of 5.0 lb/MMacf of brominated activated carbon at a sorbent cost of $1.15/lb. Note that the example does not include fuel additives or any equipment upgrade costs. EPA made following changes to the calculations between 2023 and 2024 Technical Memo's: EPA updated the Gulf Coast Hg concentration from 14.9 IlpfTBtu (2023) to 25.0 lb/TBtu (2024). This resulted in the baseline annual uncontrolled Hg emissions to change from 919 lb Hg to 1,542 lb Hg. EPA corrected the formula for conversion of sorbent injection rate from lb/MMacf to lb/hrby adjusting the conversion factor from (520 R / 785 R) to (785 R / 520 R) The conversion factor was applied incorrectly in 2023 Technical Memo. EPA added an additional factor to update the formula for conversion of sorbent injection rate from lb/MMacf to lb/hr which was not previously accounted for in 2023 Technical Memo. For comparison with the values calculated by the EPA in Table 13, it should be noted that the 2024 calculated cost effectiveness of the 800 MW example used by the EPA to meet 1.2 lb/TEki, without fuel additives, is $5,083 per pound of Hg controlled. Response: Flaws in EPA's cost analysis for future compliance with 1.2 lb/TBtu Est. Hg In (lb) & Hg Out (lb) o See previous responses on Table 12 for flipped MRY Unit 1 and MRY Unit 2 unit information/sizing and cost of fuel additive. BPAC Injection Rate: o EPA's cost analysis assumes lignite units with an ESP can achieve 1.2 IbrrBtu, which has not been demonstrated. The injection level has a direct bearing on the operational costs because it dictates the amount of BPAC necessary to reduce Hg emissions. Therefore, cost calculations are hypothetical because no project data demonstrates what the injection level would be, if 1.2 IbTTBtu is feasible. o Although the overall feasibility of complying with the proposed Hg limit is undetermined, the testing confirms that based on maximizing injection capabilities of the existing systems,MRY's current equipment configuration cannot achieve 1.2 lb/TBtu Cost of BPAC: o Table 13 brominated PAC sorbent cost-- EPA assumed of $1.15/lb. o MRY Unit 1 test campaign brominated PAC cost = $1.25/lb. Missing capital costs: o Irrespective of feasibility, EPA calculated cost-effectiveness shown in Table 13 does not include capital costs for modifying, upgrading and/or adding new equipmentthat would be necessary for the MRY Station due to limitations of existing equipment o Modification to the existing PAC injection system, would include, but not be limited to, the following: - The materials of construction of the existing PAC silo (common to MRY Units 1 and 2) is not currently compatible to store halogenated PAC. The silo would require an internal coating to prevent corrosion in order to store brominated PAC. Mercury Testing Results for the MATS Residual Risk and Technology Review Sargent S. Lundy 12 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000327-00026 SC_EVERSPLIT0012807 Minnkota Power Cooperative, Inc. Milton R. Young Station Unit 1 and 2 A14559.013 Rev. 2 May 22, 2024 s New feeding equipment, transport piping and injection lances would be required to accommodate a higher injection rate. As the existing PAC storage silo is shared by MRY Units 1 and 2, the higher injection rate required for achieving 3.0 lb/MMacffor both units would reduce the total storage duration to less than seven (7) days of storage. Due to the weather experienced at the site and the remote location, seven (7) days of storage is recommended for each unit. Improved equipment redundancy would also likely be required to accommodate the range of coal Hg expected to be experienced in the future. Therefore,it is likely that the existing equipment would be dedicated to MRY Unit 1, and a separate silo would be required for MRY Unit 2 to ensure adequate supply, turndown flexibility, and reliability is achieved to maintain compliance with a defined Hg emissionlimit. As such, a new MRY Unit 2 system would be required to achieve higher injection rates of PAC. An analogous project to install Hg control equipment at a500 MW coal-fired unit in 2021 costs roughly $5.0 million dollars, based on S&L internal mercury control database, actual project costs from recent relevart projects, and adjusted for MRY specific design Overall, the cost-effectiveness calculated is still a substantial under-estimation for the incremental Hg control on MRY Units 1 and 2. To provide an example, hypothetical MRY Unit 2 costs are summarized in the following table to underscore the magnitude of dollars that EPA failed to include in its calculations and that must be expended by Minnkota. Note the table below does not include or account for any costs associated with MRY Unit 1 system upgrades. Mercury Testing Results for the MATS Residual Risk and Technology Review Sierra Club FOIA 2025-EPA-04883 Sargent S. Lundy 13 ED_018388_00000327-00027 SC_EVERSPLIT0012808 Minnkota Power Cooperative, Inc Milton R Young Station Unt 1 and 2 A14559 013 Rev 2 May 22, 2024 Table 3-1 -- Example MRY Unit 2 Cost Underestimations Summary Parameter EPA Hypothetical 800 MW EPA Assumed MRY U2 Costs 447 MW Est. Actual MRY U2 Costs 447 MW Current Hg Compliance (4.0 IIDTTBtu) Cost 1 S2.6 M $0.3 M $1.9 M Current Hg Removed 1,295 lb 77 lb 149 lb Current C/E (S per lb Hg Removed) 2,004 3,845 12,754 Hg Control System Annualized Capital Cost BPAC Cost @ 5 lb/MMacf M-Prove Cost Not included S7.5 M Not included Not included $0.6 M $0.2 M $472k 2 $1 3 M 3 $1.6 M 4 Future Hg Compliance (@ 5 lb/MMacf) Cost S7.5 M $0.8 M $3.4 M Future Hg Removed (EPA Assumed @ 1.2 lb/TBtu) Future C/E ($ per lb Hg Removed) 1,447 lb 5 5,083 110 lb 7,040 216 lb 15,678 Incremental C/E (S per lb Hg Removed) 28,176 14,360 22,217 Note 1 -- EPA example only based on sorbent. EPA assumed current compliance cost includes sorbent and chemical fuel additive. Est. actual apst based on 2023 MRY Unit 2 usage rate & pricing for both sorbent and chemical additive. Note 2 -- Cost of $5.0 million dollars from S&L project database was annualized using a capital recovery factor calculated based on annual interest rate of 7% (pre-tax marginal rate of return on private investment, EPA Cost Manual Section 5) and 20 year evaluation period (EPA Cost Manual Section 6) Note 3 -- Cost based on EPA assumed rate but using 2023 MRY BPAC pricing. Note 4 -- Cost based on 2023 MRY Unit 2 u sage rate & pricing instead of assuming same as sorbent costs. Note 5 -- Based on calculated value for EPA example inlet Hg of 1,542 lb s (current Hg coal content)-- 95 lbs (future emitted amount). However, the EPA example identifies 1,468 lb for the increme ntal cost effectiveness calculation. Mercury Testing Results for the MATS Residual Risk and Technology Review Sierra Club FOIA 2025-EPA-04883 14 Si --gr -vt & Lulu/ay ED_018388_00000327-00028 SC_EVERSPLIT0012809