**Summary of Alternate Compliance Technology Studies**

1 The Company completed eight noteworthy technical studies to evaluate 2 NOx, PM and SO 2 emission control alternative technologies for Naughton Unit 3, 3 the first of which also apply to the Hunter Unit 1 projects included in this docket 4 for review
. In October 2002, Sargent and Lundy (“SL”) completed a fleet

-wide 5 Multi

-Pollutant Control Report as an attorney- client privileged work product; in 6 January

2 005, SLcompleted a NOx emissions reduction technologies study; in 7 March 2006, SLcompleted a Conceptual Design of Replacement Baghouse 8 PacifiCorp Naughton 3 study; in February 2007, CH2M Hill completed the BART 9 Analysis for the Naughton Unit 3 ; in December 2009, SLcompleted the SCR and 10 Baghouse Study Report; in October 2012, Alstom completed the Naughton Unit 3 11 Engineering Study to Evaluate 100% Gas Firing Fuel Heat Input; in November 12 2012, SLcompleted the Naughton Station Conversion of Unit 3 to 100% Natural 13 Gas Firing study; and in March 2013, Alstom completed the Naughton Unit 3 14 Engineering Study to Evaluate 100% Gas Fuel Input Including Evaluation of Flue 15 Gas Recirculation and Low Load Operation. 16 1. The Multi

-Pollutant Control Report provided an early investigation of the cost 17 and necessity o f NOx, particulate matter (“PM”) and sulfur dioxide (“SO 2”) 18 emission controls on the units. 19 2. The 2005 NOx emission reduction technologies study compared sixteen 20 emission control technologies, status of the technology development, 21 predicted performance, approximate initial capital costs, and approximate 22 incremental fixed and variable operational and maintenance (“O&M”) costs
. 233. The Conceptual Design of Replacemen t Baghouse PacifiCorp Naughton 3

24 study

established initial capital costs for PM emissions control alternatives. 25 4. The BART Analysis for the Naughton Unit 3 was conducted for criteria 26 pollutants NOx, PM 10 and SO 2 . The Company conducted the BART analysis 27 and determination to analy ze the effects on visibility in nearby Class I areas 28 (Bridger, Fitzpatrick and Mt. Zirkel Wilderness Areas). A BART analysis is a 29 comprehensive evaluation of potential NOx, PM and SO 2 retrofit 30 technologies, and a BART determination is an emissions limit established by 31 the application of potential retrofit technologies for each unit. The specific 32 steps in a BART analysis are established in 40 CFR 51 Appendix Y, Section 33 IV
. The analysis must include: (1) the identification of available and 34 technically feasible retrofit alternatives; (2) consideration of any pollution 35 control equipment in use at the source (which affects the availability o f 36 alternatives and their effects); (3) the costs of compliance with control 37 alternatives; (4) the remaining useful life of the facility; (5) the energy and 38
non- air quality environmental impacts of compliance; and (6) the degree of 39 visibility improvement that reasonably may beanticipated from installation of 40 the BART alternative. 41 5. The SCR and Baghouse Study Report evaluated and established design criteria 42 and specified critical equipment features to mitigate design risks for a SCR 43 and baghouse technology alternative. 44 6. The Naughton Unit 3 Engineering Study to Evaluate 100% Gas Firing Fuel 45 Heat Input assessed the boiler thermal performance impacts; firing system 46performance and emissions impacts; controls impacts; and potential boiler

47 pressure part and firing system component modifications that may be required 48 to add natural gas firing capability to the unit based on operation with 100% 49 fuel heat input at full load. 50 7. The Naughton Station Conversion of Unit 3 to 100% Natural Gas Firing 51 study

investigated the scope of work and estimated costs for converting the 52 unit from a base loaded coal unit to a natural gas fueled peaking unit while 53 leaving coal firing capability intact to the greatest extent practicable. 54 8. The Naughton Unit 3 Engineering Study to Evaluate 100% Gas Fuel Input 55 Including Evaluation of Flue Gas Recirculation and Low Load Operation 56 assessed thermal performance of the unit at low load and provided an 57 evaluation of NOx emissions control using a FGR alternative at both high and 58 low loads. 59 **Key Study Points** 60 Salient points from these eight studies, and related information from other 61 sources, are presented with following statements: 62 The Multi

-Pollutant Control Report indicated that combination “in

63 combustion” (Low NOx Burners with Over Fire Air) and “post combustion” 64 (Selective Cataly tic Reduction) would need to be installed on Hunter Unit 1 to 65 achieve a presumptive NOx emission rate of less and 0.10 pounds per million 66 British thermal units (lb/mmBtu) 67 The Multi

-Pollutant Control Report indicated that a combination of “in

68 combustion” and “post
- combustion” controls (namely a S CR) would need to be 69installed on Naughton Unit 3 to achieve a presumptive NOx emissions limit of

70 less than 0.10 pounds per million British thermal units (“lb/mmBtu”). 71 The Multi

-Pollutant Control Report indicated that the Hunter Unit 1 ESP 72 could achieve a particulate emission level of 0.030 lb/mmBtu with reasonable 73 modifications and upgrades, and it further indicated that that maintenance costs 74 would need to increase over time to facilitate the rebuilds necessary to keep the 75 current equipment operational at historic levels. Inorder to achieve an emission 76 level below 0.020 lb/mmBtu, the Multi

-Pollutant Control Report indicated a 77 polishing baghouses retrofit would need to be completed. 78 The Multi

-Pollutant Control Report indicated that Naughton Unit 3 would 79 require extensive modifications to the existing ESP or a “polishing baghouse 80 retrofit” must be completed to meet a presumptive PM emissions limit of less than 81 0.030 lb/mmBtu. The Naughton Unit 3 ESP is the smallest in the Company ’s coal 82 fleet, is about 40 years old, and is in poor condition. Itdoes have a flue gas 83 conditioning system to improve its p erformance. Historical operating data 84 establishes that the existing ESP’s best PM emissions rate is only a pproximately 85 0.04 lb/mmBtu. 86 The Multi

-Pollutant Control Report indicated that the Hunter Units 1 FGD 87 system could achieve a removal efficiency o f 90% with the following system 88 upgrades: (1) close the scrubber by pass damper (2) upgrade the existing mist 89 eliminators (3) add vertical flow mist eliminators (4) improve inlet gas 90 distribution (5) upgrade existing reheat system (6) upgrade spray header and 91nozzle system (7) replace existing spray pumps (8) convert to a forced oxidation 92 system (9) restore and upgrade dewatering equipment. 93 The Multi

-Pollutant Control Report, and other sources, indicated that a 94 FGD upgrade SO 2 removal efficiency o f 90% would be achieved on the existing 95 Naughton Unit 3 FGD with only minor changes including: (1) improvements to 96 the inlet gas distribution; (2) the liquid to gas contact point would need to be 97 reviewed; (3) reagent and waste delivery systems needed to be upgraded; (4) a 98 reagent adjustment; and (5) consideration of a conversion to an open spray type 99 absorber. 100 At units with high baseline NOx emissions (high is defined here as being 101 greater than 0.40 lb/mmBtu), it is common utility industry practice to initially 102 obtain a NOx emissions reduction through the installation in

- combustion 103 modifications, similar to the LNBs installed on the units, and then control the 104 remainder of any required NOx emissions reduction with post

- combustion control 105 systems, ty pically either SCR or a selective non- catalytic reduction system 106 (“SNCR”)
. 107 NOx control technologies are grouped as either in

-combustion control, 108 post
-combustion control or emerging ty pes: 109

• In
- Combustion Controls include: (1) LNBs with overfire air (“OFA”); (2) 110
more precise combustion control of fuel and air; (3) combustion optimization 111 using a Neural Network system; and (4) Nalco Mobotec rotating opposed fire 112 air (“ROFA” or “rotating opposed fire air”) which is a next generation OFA 113 system. 114• Post
- Combustion Controls include: (1) SNCR, ty pically limited to only

1 0 to 115 40 percent NOx emissions reduction and have higher ammonia slip rates; and 116 (2) SCR with 80 to 90 percent NOx emissions reduction and a low ammonia 117 slip rate. 118

• Other emerging NOx reduction technologies (and that might become 119 commercially available, or more commercially feasible, within the next 120 decade) with the capability to achieve required NOx removal percentages 121 include: (1) Regenerative Activated Coke Technology; (2) Powerspan Electro

122 Cataly

tic Oxidation; (3) BOC LoTOx System; (4) Airborne Process; (5) 123 Consolv Technologies Absorption Process; (6) Lean Gas Reburning; (7) Rich 124 Reagent Injection; (8) SNCR plus SCR hy brid systems; (9) Aptech CST 125 SNCR ty pe systems; and (10) other reagent injection developments. 126 Of the technology alternatives mentioned herein, only L NB with OFA, 127 ROFA, SNCR with LNB, and SCR with LNB were considered BART analysis 128 feasible alternatives for NOx reduction across the fleet. 129 In a SCR, ammonia (“NH3 ”) reacts with NOx contained in the flue gas 130 exiting the boiler as either nitrogen oxide (“NO”) or nitrogen dioxide (“NO 2”) in 131 the presence of catalyst to form molecular nitrogen (“N2”) and water (“H2O”). 132 Catalyst enhances the reaction between ammonia and NOx. The injected air

133 diluted ammonia is adsorbed on the catalyst surfaces in the SCR reactors and 134 reacts with oxygen and NOx present in the flue gas according to the following 135 chemical reaction equations: 136 4NH3 + 4NO + O 2 → 4N2 + 6H2O 137 4NH3 + 2NO 2 + O 2 → 3N2 + 6H2O 138SNCR technology i s similar to SCR because it involves injection of an 139 amine reducing agent like urea solution. The reduction chemistry, however, takes 140 place in the boiler without the aid of any c atalyst. SNCR relies on appropriate 141 injection temperatures, proper mixing of the reagent and flue gas, reagent 142 injection kinematics, and prolonged boiler detention time in place of the catalyst. 143 SNCR operate at higher temperatures than SCR. The effective temperature range 144 for SNCR is 1,600 to 2,100 degrees F. SNCR i s sensitive to temperature changes. 145 Table NT3
- 5
- 1 summarizes a comparison of NOx emissions control 146 technologies results adapted from the BART Analysis for the Naughton Unit 3 on 147
a 2007 cost year basis: Other environmental project costs not included in the 148 BART estimates include: boiler and air preheater casing structural reinforcements, 149 flue gas path structural reinforcement, a high and low temperature EEGT control 150 system, demolition, auxiliary power system upgrades, Owner’s project costs and a 151 contingency allowance
. 152**Table NT3 -** **5 -**  **1: Oxides of Nitrogen Emissions Control Technologies Comparison**

**(Adapted From CH2M Hill BART Analysis)**

Technology Projected

Emission Rate (lb/mmBtu) Projected

Emission % Reduction (%) (b) Capital Cost

($ x million) O&M Cost

Fixed + Variable ($ x million) Annual

Power Usage (1,000 MWh/y r) First Year Avg. Cost For NOx Removal ($/ton)
Baseline 0.50 (a) 0% 0.0 0.0 0.0 0 LNBs with OFA 0.35 22.2% 0.0 (c) 0.1 0.0 0 ROFA 0.28 37.8% 14.7 1.9 35.3 1,326 Selective Non

Catalytic Reduction and LNBs with OFA 0.28 37.8% 15.8 0.9 2.6 984
Selective Catalytic Reduction and LNBs with OFA 0.07 84.4% 92.0 2.6 15.7 2,049 (a) Emissions from PIdata in table below; prior to LNB and OFA installations on Unit 3, the uncontrolled emissions rate was approximately 0.50 lb/mmBtu (b) Technology reduction rates from the CH2M Hill BART analysis shown (c) Currently installed on Naughton Unit 3 The baseline NOX concentration of 0.50 lb/mmBtu was established from 153 Naughton Unit 3 performance historian (“PI”) data and confirmed with 154 continuous emissions data and flue gas testing. 155 PM emissions control technologies evaluated for Naughton Unit 3 include: 156 (1) install a stand

- alone baghouse to replace the existing ESP; (2) install a 157 polishing fabric filter (Compact Hy brid Particulate Collector or (“COHPAC”)) to 158 operate in series with the existing ESP; (3) rebuild the existing ESP; and (4) 159 replace the existing ESP with a Reversing Gas Fabric Filter (“RGFF”), which is a 160 PM cleaning device currently not often selected for use in steam electric plants. 161 Feasible technical alternatives to meet a PM emissions compliance limit of 162 0.015 lb/mmBtu are: (1) install a polishing baghouse and operate it in series with 163a rebuilt ESP; and (2) install a stand

- alone baghouse. The Design of Replacement

164 Baghouse PacifiCorp Naughton 3 study e stablished initial capital costs in 2006 165 dollars for these two alternatives. 166 The Naughton Unit 3 Engineering Study to Evaluate 100% Gas Firing 167 Fuel Heat Input reported that the unit can be converted from the current coal 168 firing configuration and made capable to operate at full load on 100% natural gas 169 without significant boiler equipment or pressure part modifications. NOx 170 emissions of approximately 0 .09 to 0.12 lb/mmBtu were predicted with natural 171 gas firing, consequently indicating it would be necessary to install a post172 combustion SNCR process or other post- combustion NOx control process if a 173 NOx emissions limit of approximately 0 .08 lb/mmBtu is required. An alternative 174 FGR was proposed instead of adding a post

- combustion NOx control system. The 175 FGR can simultaneously achieve the desired NOx emissions limit at 0.08 176 lb/mmBtu while also achieving design steam temperatures more easily and over a 177 broader load range. Alstom offered an opinion that potential furnace 178 modifications that include FGR and or waterwall refractory alternatives would 179 provide greater flexibility f or NOx and carbon monoxide (“CO”) control when 180 firing 100% natural gas, and would be necessary from a performance standpoint if 181 the boiler were to be operated at low loads. 182 The Naughton Unit 3 Engineering Study to Evaluate 100% Gas Fuel Input 183 Including Evaluation of Flue Gas Recirculation and Low Load Operation 184 reported that Naughton Unit 3 can be converted from the current coal firing 185 configuration and made capable to operate at full load on 100% natural gas 186without significant boiler or pressure part modifications. The addition of a FGR is

187 required to mitigate steam temperature reductions when attempting to attain 188 required NOx emissions at full load. A FGR is also required to maintain high final 189 reheat steam temperatures at a low load of approximately 8 5 MW. Alstom 190 reported an FGR operated at about 20% FGR at full load, operated in conjunction 191 with Alstom’s recommended natural gas firing system and the existing SOFA 192 system, is predicted to result in a NOx emissions range of 0.06 to 0.09 lb/mmBtu 193 and a CO emissions rate at less than 0.15 lb/mmBtu. 194 Beyond the eight studies discussed above, The EPSCO International, Inc., 195 Phase III Recommendations study o f the Hunter and Huntington electrostatic 196 precipitators (ESP) was used as the basis for the decision to convert the Hunter 197 Unit 1 ESP to a baghouse. The decision making process began when the same 198 ty

pe of conversion was made at Huntington Unit 2 (2004

-2006)
. The ESP at 199 Hunter Unit 1 and Unit 2 and Huntington Unit 1 and Unit 2 are identical and in 200 2003 it had become apparent that the ESP’s were having operational difficulties
. 201 EPSCO International, Inc. was hired to study the situation, identify

options and 202 make recommendations for the Huntington and Hunter units. The EPSCO report 203 titled Phase III Recommendations was published in November 2003. 204