DEI'ARTME T OF ENVmONMENTAL QUALITY DIVISION OF AIR QUALITY Permit Application Analysis, NSR-AP-C92 April 24, 2002 COMI)ANV: FACILITY: FACILITY LOCATION:

TYPE OF FACILITY: RESPONSIBLE OFFICIAL:

COMPANY REI)RESF:NTATIVE:

MAILING ADDIU:SS:**I~EVIEWEO** 

### BY:

1'11HI'OSF: OF AI'!'I.IC'ATION: 

### Black I-IIlis Corporation WYOEN2 13151 Highway 51 

### Gillette. WY Section 27, T50N, R71W Campbell County, Wyoming Coal Fired Steam Electric Generating Plant Tom Ohlmachcr Senior V,P. Power Supply and Operations Fred Carl Environmental ("oordlnator P.O. Box 1400 Rapid City, SO 57709-1400 Stewart Grmer, AirQuailly Engmeer Ken Raingh, AIr Quality Engmeer/Modeler

Bllll.:k Hills Corpuratmll submlllcd an appllcatlun tu wnslrUCI a 500 megawall (MW) pulvcrli"cd coal (PC') fired electnc generatmg 

### faCIlity to be known as WYGE r2. '111c proposed 

### facilIty consists ofone 1'(' builer bummg coal from the nearby Wyodak coal mme wIth assocIated CO:J1 and [unc handlmg and nuc gas dcsulfufl7...atlon (FGD) waste product handling. !'arametcrs used for deSIgn values, based on coal frol11lhc Wyodak mme. mclude a deSign heat content of7,950 Btullb and a maximum sulfurcontent of 1.2%. The maximum deSIgn he:lllnpllt 10 Ihe faCIlIty will be 5,145.7 MMBlu/hr. The appllcanl Idcntllicd Ihc followlIlg emIssion sources in thc pCIll1it appllcatlon:Black JiJlls CorporatIon (WYGEN 2) PermitApplictJllOn Analysis. NSR-AP-C92 Page 4



### 3) An Increment consumption analysis IS required for regulated pollutants based on allowable emissIOn rates as well as incrementconsumingemissions from othersources in theregion. The lotal deterioration determined from this analysis mustcomply with the allowable increments established for PM

### ,o, 

### S02' and NO. for the classification of

### the area (i.e. Class 

### IorClass 

### U) in which the Increment consumption is predicted. 4) An analysis IS required to assess the Impairment to viSibility, soils, and vegetation resulting from the facihty and general commercial, residential, industrial, and othergrowth associated with the faelilly. BEST ,\VAILABLE CONTROL TECHNOLOGY (BACT): A best available control technology (BACI) analysis for NO

### x • 502, PMlPM IO, CO, VQC, H2 SO., and nuonde is reqUIred because each ofthesepollutants is emitted above PSO significantemission rates. Additionally, a 

### BACfanalySIS is required for beryllium and mercury underChapter

### 6, Section4(a)(x.xi) ofthe \V

### AQSR. The 

### BACfanalySIS for each emission source is presented in the following sections: I. 

### 500 MW PC Uoilcr

- NO, Control Black Ililis Corpor:ltion proposed low NOx burners and SCR wllh an cmlSSlOn 1Imlt ofO.09lb/MMBtu as BACT The DIVISion reviewed the RACf/BACT/LAER C'leannghouse (RBLC) and information from EPA Regional offices to find permitted orproposed PC uulny boilers With NO, emiSSions equal or lower than 0.09 IblMMBtu as shown m the following table:

Facilny Statc Sizc Control NOx Emissions Status (MW) Device (Ib/MMBlu) Kal1s:ls City Power & Light Co.

- MO 

### 570 

### SCI( O.OX (30 day)' Opcrtllional Ilawthomc StatlOll May

### 200!

0.12 Ib/MMl3tu (30day) hmit for first 3years, Lhen0.08Ib/MMBtu Ifdemonstrated 

### fC3!'ilb1c. Accordlllg to Missoun DNR. Hawthorne StatIon is currently meeting the 0.08 Ib/MMBtu limIt. 

# •(irca! Plall1s Powcr

- Weston Bcnd

(jencralll1g SlatIon MO 

### H20 

### SCI( O.OX (30 day) Proposed

EmiSSion Control Technologies Black I!Ills CorporatIon conSIdered thc followmg controls for NOx reductIOn: COmbll,\f;O/l tollfrols - Low NOx humcrs (LNB). ovcrfirc lIlr(OFA). and advanced gas rebum (AOR) all serve \() rcduce JX'ak cnmbustulIllcmpcratures thus lowcnng NOx cmlSSlOns. Although nonc ofthese C0l1lrols com Jchlc\c**Crnl~S1tl11** Icvcb comparable 10 pUSI comhusllon controls. they do prevcnt somc of the Illltla] li)nnal1tlll IlfNU>... 1.31ack II dis Corpor.Jllon**~clt:l':h:J** 10\\ NOx burners 11\ combmatlon wtlh 1)(ISI-comhu

..Il1111 ctllliruis hCC:lu<;c thc l<mcr emlSSlOllS gClll'r<ltcd n:<;ult In 10\\cr caplinIcost and reagent usclack 111115 Corporallon (WYGEN 2) ?enrut ApplicationAnalYSis, NSR·AP-C92 ?age 5 

### Selective CoralyticReduction (SCR)

- SCR is apost combustion control techmque in which the flue gas IS combined with 

### vaporized ammonia in thepresence ofa catalyst and**NO~** 

### isreduced to nitrogen and water. Black Hills Corporation evaluated SCR at emission levels of0.06, 0.08, and 0.091b1MMBtu. 

### SelectiveNon-CatalyticReductio" (SNCR) • SNCR is SImilarto SCR in that it involves the injection ofa reducmg agent such as ammoma orurea into the flue gas stream. The reduction chemistry, however, tnkes place Without the aid ofacatalyst. SNCR systems rely on appropriate injection temperatures, pror>cl' reagent/gas mixing and prolonged retcntion time in place ofthecatalyst. SN R systems are very sl.:nsitive to temperature changcs and typically have loweremissions reduction (up to fifty 

### or sixty percent) and higher ammonia slip. BlackHills Corporation did nOI further consider SNCRbecause ofthe lower emissions reduction and the lackofany operational advantage 

### over SCR. 

### JJyhridSNCRJCatalysl System. These systems were developed to combine the relatively lowcapital COSI 

### and high ammonia slip associated with SNCR with the high reduction potential and low ammonia slip !Oherent to SCR. '1l1C 

### first part ofthe systemis 

### atypical SNCR system with increased reagent now for additional NOx

### reduction. A 

### small catalyst follows to reduce ammoma slip and poSSibly achieve addItIonal Ox 

### reduchon. This systemrequires more ammonia but uses a smallercatalyst. Black Hills Corporation did not furtherconSider ahybnd systembecause ofpoSSible problems achlevmg adequatc dlstnbutlon ofammoma and because there is no operatIOnal orClnlSSlOn reduction advantagc over SCR. I:nergy and EnVironmental Evaluation Black Ihils 

### Corporation evaluated the energy and environmental considerations for SCR. An SCR 1>ystemconsumes electncal energy for ammonia transportand vaponzallon and for incremental fan ucmand to overcome pressure drop across the catalyst. EnVironmental callSlllcrallons mcludc ammOOlil 

### slip. a slight IIlcrcase in SOl emiSSions, apossible slight mcn:aSl: In PMlo 

### ellllSSlons. and ammonia handlmg and storage. Ammoni,1 sl1p emissions of2 to 5 ppm and tl 

### I (02 

### pcn;cnl lllcrcasc 1n 

### SOl emISSIons are cxpech.:d. Unrcaclcd 

### allllllOllla ,md SOl can react 

### to form <lmtllOnla 

### hisLJIfate and amtllOlll(l Slllfale >;.ills It1 

### Ihe form ofPM III 

### ellllSSlons. Allllllonia is a ha/.anJolls Illtltenal and adequate design prcc,llltions nrc necessary for bandllllg and**~torage.** b.:onOIllIC 

### bvaluatlOl1 ofAlternatives l3Iack IlIlIs CorporJ.tlOn evaluated the combmation ofLow NOx burners and SCR at emiSSIon levels of 0.06,0.08, and 0.09Ib/MMBtu. An cconoml7.crbypass IS 

### required to keep temperatures m the opllmum range morderto meet the 0.06 or 0.08 IbIMMl3tu emiSSion limits at 50% load. Consequently, the mcremental cost IS higher from 0.09 Ib/MMBtu to 0.08 IbII\lMBtu than from O.09Ib/MMB1U to le"els lower than 0.08 IblMMRtu. The results are shown III 

### the followmg table:Black Ilil1s Corporation (WYGEN 2) PemutApplication Analysis, NSR-AP-C92 Page 6

Annual Emissions EmiSSions ReductIOn Total Annualized Cost Total Cost Effectiveness Incremcntal Reduction· Incremenlal Annualized Cost Incremental Cost Effectiveness Baseline 

### 0.25 IblMMBtu 5,635tpy Baselinc Baseline Baseline 

### LNB/SCR LNB/SCR LNB/SCR 0.091b1MMBtu 0.08 Ib/MMBtu 0.061b1MMBtu 2.028 tpy 1,803 tpy 1,352tpy 3,606tpy 3,832 tpy 4,283 tpy $12,563,000 515,582,000 $17,798,000 

### 53,484/to" S4,067/to" $4,1561ton

Baseline 

### 225 tpy 676tpy Baseline 

### 53,019,000 55,235,000
Baseline 

### 513,395/too $7,7421ton

• 11lc DIvision calculatcd incremental coslo; based on a 0.09 Ib/MMBtu baseline forboth 0.08 and 0.06 Ib/MMBtu becausc an economizerbypass is required 10 achieve either0.08 or 0.061b1MMBlu. Black IItlis Corporation chose 0.091b/MMHtu as BACTbecause they consIdered the Incrcmental cost effectiveness to be unreasonable for the loweremISSion levels and because they were unablc to find an Issued permit With a [1I1l\t less than 0.12 IblMMBtu for a PC boiler. (Note thai the Ilawthomc Station boder III MISSOUri has a lImit ofO.12lbfMMBtu for 3 years and then a limit ofO.081b1MMBtu unlcss the penlllltec can demonstrate th:lt 0.08 IbfMMBtu is not feasible.) According to Missouri DNR, Hawthome StatIon IS mcctlllg the 0.08 [bfMMBtu limIt. Missouri DNR IS also working on a pcrmlt for Greal Plallls Power WIth a proposcd llllllt ofO.08IbfMMlltu. Although Grcat Plall1s Power requested 3 years 10 detl:rmlne Ifthey can comply with the limit as allowed in the Hawthorne Stallon penllit, Missoun DNR IIldlcaled that they do !lot pl:lll to issue the permit with any execpllons 10 Ihe O.08Ib/MMBtu hmlt. The l)IVI:-:lon CvUlll:Lted the control effiCIency requIred to mcctltmlts 01'0.09, 0.08, and O.061b/MMBtl,J llStng a baseline of0.25 Ib/MMBtu ns shown In the followll1g tnblc: EmISSion Levcl



### (lblMMBtu) 0.09 0.08 0.06 Control Efficll:!lcy (%) 

### 64 68 76

rhese cffiClcncles sccm low based on mfomlalton that vendors arc deslgmng and provldmg guarantee... ror SCI{ systems \\'Ith at lcasl90110control efficlcncles. For example. Montour Steam Elec,;tnc Slatum III AlIcntown. PA rl'lrufllted 1\\'0 750 fl,IW coal fired hollers \\llh SCR systems deSigned for 90% control cfliclclleyund 1).1)" Ib fl,1fI,lBtu USl11g castcrn bltUtnlllOm, coal It .!>hould 

### be noted that Ihese arc deSign levels tn mcet aCIl! ram rcqUlrcmcnts and there arc no penlllt Ilmlls rcqulfIng thIS level ofrcduC\lon.BlackJlllls Corporation(WYGEN2) Permit Application Analysis, NSR4AP..c92 Page7 The BACI' analysis indIcates that0.06lb1MMBtu is technically feasible and 

### the Division considers the total and incremental cost effectiveness to be reasonable. Note thatthe incremental cost effectiveness is much lower when conSIderingemission limits less than 0.08 IblMMBtu becausean economizerbypass is required to achieve emission limits ofO.08lb1MMBtu or less. Although the BACTanalysis indicates an emission level ofO.06Ib1MMBtu, Black Hills Corporation has expressed uncertainty about meeting0.06 IbIMMBtu on a continuous basis. The Division and Black Hills Corporation discussed various options for dealing with this uncertainty while setting an appropriate BACT level. Oneoption discussed was 0.06 Ib/MMBtu annual average and 0.08 IblMMBtu 30 day average. This option still len BlackHills Corporation with a measure ofuncertainty in regards to meeting Iheannual limit and they requested that the O.06Ib/MMBtu limit not become effective until issuance oftheTitle V operating pennitin order to allow additional time to demonstrate compliance. Even with the additional time for compliance, Black Hills Corporation expressed concern about meeting a0.061b/MMBtu limit and discussed options ifthey could not meet the limit. Upon further discussion, the Division and Black Hills Corporation agreed that a 30 day limit ofO.071blMMBlu would be more stringent than anyexisting limit for an operating PC boiler and could be met Without additional time to demonstrate compliance. The Division concludes that 

### Low NOx. burners and SCR with an emission limit ofO.07lb1MMBtu

## pO day

### rolTmg average) represent 

### BACT.

- 

### II. 500 MW PC Boiler 4 

### SO, Control Black 1II1IsCorporation proposed a seml-dry lime spray dryerabsorber with emiSSion hmlts of0.15 Ib/MMBtu (30 day average) and 0.17 Ib/MMBtu (2 hour block). 'me Division reviewed the 

### RACr/BACrfLAERCleannghouse (RBLC) and mfonnatlon from EPA Regional offices 10 find pennitted or proposed PC utilityboilers with 

### 502emiSSIOns lowerthan 0.15 IbIMMBtu as shown in the followmg table: