Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle



# TOXECON TM Retrofit for Multi-Pollutant Control on Three 90-MW Coal-Fired Boilers

Topical Report: Performance and Economic Assessment of Trona-Based SO 2 

# /NO x 

# Removal at the Presque Isle Power Plant

Prepared for: We Energies DOE/NETL

Prepared by: ADA-ES, Inc. 8100 SouthPark Way, Unit B Littleton, CO 80120 (303) 734-1727

August 25, 2008Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

i 

## Table of Contents

Summary........................................................................................................................ .......... 1

Introduction................................................................................................................... .......... 1 Background ..................................................................................................................... ........ 2 Test and Equipment Description........................................................................................... 3 Trona Background Information...................................................................................... 4 Trona Injection Equipment ............................................................................................. 4 Trona/Ash Unloading Issues............................................................................................ 7 SO 2 , NO x and Opacity Measurement.............................................................................. 7
Test Results................................................................................................................... ........... 8 Baseline Testing ............................................................................................................... . 8 Parametric Testing ......................................................................................................... 10 Schedule and Materials Handling........................................................................ 10 SO 2 and NO x Removal .......................................................................................... 11 Baghouse Pressure Drop and Cleaning Frequency............................................ 15
Economic Assessment of Full- Scale Trona Injection......................................................... 17

Introduction................................................................................................................... .. 17 Process Design................................................................................................................. 17 Trona Injection System......................................................................................... 17 Ash Handling System ............................................................................................ 19 Cost Estimates and Results............................................................................................ 20 Capital Costs.......................................................................................................... 20 Operating and Maintenance Costs ...................................................................... 22 Levelized Costs ...................................................................................................... 25 Removal Cost per Ton of SO 2 Removed ............................................................. 28
Conclusions.................................................................................................................... ........ 30

References..................................................................................................................... ......... 31

APPENDIX A – Cost Estimates and Results – Details...................................................... 32 Capital Costs.......................................................................................................... 32 Operating and Maintenance Costs ...................................................................... 34 Levelized Costs ...................................................................................................... 39 Removal Cost per Ton of SO 2 Removed ............................................................. 46Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

ii 

## List of Tables

Table 1. Schedule of Activities for SO 2 /NO x Control Testing................................................. 3 Table 2. Trona Injection Results. ............................................................................................ 1 1 Table 3. System Design Criteria for SO 2 Control System at Presque Isle (6000 lb/hr injection, >70% SO 2 control). ........................................................................................... 18 Table 4: Summary of Equipment, Balan ce-of-Plant, and Engineering Costs...................... 21 Table 5. Total First-Year Fixed Operating & Maintenance Costs....................................... 23 Table 6. Variable First-Year Operatin g & Maintenance Costs for Power ......................... 24 Table 7. First-Year Variable Operating & Ma intenance Costs for Sorbent Delivered by Rail and by Rail/Truck Combination to the Plant.......................................................... 24 Table 8. First-Year Variable Operating & Ma intenance Costs for Landfill Waste Disposal

............................................................................................................................... ............... 25 Table 9. First-Year Total Variable Operating & Maintenance Costs ................................. 25 Table 10. Economic Factors and Parameters......................................................................... 26 Table 11. Levelized Capital Costs............................................................................................ 2 6 Table 12. Total Levelized Fixed Operating & Maintenance Costs ...................................... 27 Table 13. Levelized Total Variable Operating & Maintenance Costs ................................. 27 Table 14. Total Levelized Costs (Capital and Fixed & Variable O&M Costs) ................... 28 Table 15. Removal Cost per Ton of SO 2 ................................................................................. 29 Table 16. Summary of Equipment, Balan ce-of-Plant, and Engineering Costs ................... 33 Table 17. Fixed O & M Costs – Ash Handling Labor Cost Parameters............................. 34 Table 18. Fixed O & M Costs – Ash Handling Labor Costs for Three SO 2 Removal Rates

............................................................................................................................... ............... 35 Table 19. Fixed Operating & Maintenance Co sts for Equipment Operating, Maintenance and Support Labor ............................................................................................................ 35 Table 20. Total First Year Fixed Operating & Maintenance Costs ...................................... 36 Table 21. Power Requirements to Run Trona Injection System .......................................... 37 Table 22. Variable Operating & Maintenance Costs for Power .......................................... 37 Table 23. Variable Operating & Maintenance Costs for Sorbent Delivered by Rail to the Plant .......................................................................................................................... .......... 38 Table 24. Variable Operating & Mainte nance Costs for Sorbent Delivered by a Combination of Rail and Truck to the Plant................................................................... 38 Table 25. Variable Operating & Maintenanc e Costs for Disposing the Waste to the Landfill....................................................................................................................... ......... 39 Table 26. Total Variable Operating & Maintenance Costs .................................................. 39 Table 27. Levelized Capital Costs............................................................................................ 4 0 Table 28. Levelized Fixed Operating & Maintenance Costs for Ash Handling Labor ...... 41 Table 29. Levelized Fixed Operating & Ma intenance Costs for Equipment Operating, Maintenance, and Support Labor .................................................................................... 41 Table 30. Levelized Total Operating & Maintenance Costs ................................................. 42 Table 31. Levelized Variable Operatin g & Maintenance Costs for Power ......................... 42 Table 32. Levelized Variable Operating & Ma intenance Costs for Sorbent Delivered by Rail to the Plant.............................................................................................................. .... 43 Table 33. Levelized Variable Operating & Ma intenance Costs for Sorbent Delivered by a Combination of Rail and Truck to the Plant................................................................... 43Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

iii Table 34. Levelized Variable Operating & Maintenance Costs for Waste Disposal.......... 44 Table 35. Levelized Total Variable Operating & Maintenance Costs ................................. 44 Table 36. Levelized Costs (Capital, Fixe d, and Variable Levelized Costs) .......................... 45 Table 37. Removal Costs per Ton SO 2 Removed .................................................................... 46



## List of Figures

Figure 1. Staging Area for Trona Injection Equipment.......................................................... 5 Figure 2. Trona Injection Tra iler Blowers and Controls........................................................ 6 Figure 3. Injection Ports..................................................................................................... ........ 7 Figure 4. Baseline SO 2 and NO x Data ....................................................................................... 9 Figure 5. Unloading Reacted Trona/PAC/Ash Mixture........................................................ 10 Figure 6. SO 2 Removal vs. Trona Injection Rate................................................................... 12 Figure 7. SO 2 Removal Profiles. .............................................................................................. 12 Figure 8. NOx Removal During Trona Injection................................................................... 13 Figure 9. Effect of 5926 lb/hr Trona Injection on SO 2 , NO x , and Opacity.......................... 14 Figure 10. Effect of 5926 lb/hr Trona Injection without PAC Injection.............................. 14 Figure 11. Baghouse Operation Duri ng Trona Injection Testing. ....................................... 16 Figure 12: Schematic of the Trona Injection E quipment at Presque Isle Units 7, 8 and 9. 19



## List of Acronyms

DOE Department of Energy PAC Powdered Activated Carbon NSR Normalized Stoichiometric Ratio MMacf Million actual cubic feet of flue gas O&M Operating & Maintenance EPRI Electric Power Research Institute CEM Continuous Emissions Monitor RATA Relative Accuracy Test Audit TCR Total Capital RequirementTopical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

1 

## Summary

Under a DOE Clean Coal Program, activated car bon injection has been used to demonstrate continuous mercury removal at We Energies’ Pres que Isle Power Plant (PIPP). Trona injection tests were also performed at PIPP from July 31 through August 10, 2007. The purpose of these tests was to determine if dry trona injection prior to the TOXECONTM baghouse would result in at least 70% sulfur dioxide (SO 2 ) reduction, and to assess any related change in mercury removal. Some minor nitrogen oxide (NO x ) reduction was also antici pated from these tests. Balance of plant issues associat ed with trona injec tion and subsequent ash handling were also evaluated.

A temporary injection system was set up near the Units 7-9 stack with individual hoses and lances feeding each of the Unit ducts. The inj ection point was near the existing PAC injection ports in each duct and downstream of the plant NO x analyzers used for boiler feedback. SO 2 and NO x analyzers were temporarily in stalled upstream of the trona injection point on each of the three ducts for monitoring during th e tests. Existing analyzers were used at the stack to measure SO 2 , NO x , and opacity.

During the test period, the trona in jection rate was varied, which pr ovided the data necessary to complete an SO 2 removal curve. Powdered Activated Ca rbon (PAC) injecti on continued at pretrona injection test levels with trim control on, which allowed some variability (+/- 20%) in injection rate. PAC injection wa s turned off one day to determine if there was an effect from PAC on SO 2 removal. Due to a negative effect fr om trona injection on mercury removal, PAC injection was increased on one day to try to regain a >90% removal rate.

The goal of 70% SO 2 removal was achieved during this tw o week test period when using 5926 lb/hr of trona. This corresponds to an averag e Normalized Stiochiometric Ratio (NSR) of 1.02. The NSR is the molar ratio of the sorbent injected to that theoretically required for complete reaction with SO 2 . The inlet concentration of SO 2 varied from 0.48-0.64 lb/MBtu. The highest removal was 74.1% with PAC inject ion at 3.8 lb/MMacf. There was very little reduction in total NO x during the test period, although the presence of the side reaction with NO producing NO 2 was observed during when PAC injection was turned off. Injection of trona for SO 2 control resulted in a decrease in mercury removal us ing activated carbon. The mercury removal slowly recovered overnight to the pre-trona injection levels of >90%.

An economic assessment of a full-scale trona in jection system included equipment and other capital costs along with sorbent cost (trona and increased amo unt of PAC to maintain 90% removal) and O&M costs. The cost to remove SO 2 varied from $1,448/ton at 45% removal and one silo to $2,231/ton SO 2 at 70% removal with 3 silos.



## Introduction

We Energies’ Presque Isle Power Plant is the si te of a DOE Clean Coal demonstration project being conducted under a cooperative agreement with Wisconsin Energy Corporation and the Department of Energy (DOE). The primary goal of this project is to reduce mercury emissionsTopical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

2 using a TOXECONTM system designed to clean the combined flue gases of Units 7, 8, and 9 at the Presque Isle Plant. An additional goal is to reduce NO x and SO 2 emissions.

TOXECONTM is an Electric Power Research Instit ute (EPRI) patented process in which a fabric filter system (baghouse) installed downstream of an existing particulate control device is used in conjunction with sorbent injection for removal of pollutants from co mbustion flue gas. The flue gas emissions are controlled from the three units using a single baghouse. Mercury is controlled by injection of activated carbon, while NO x and SO 2 reduction was tested by injection of sodium-based sorbents. Both the mercury and SO 2 /NO x control sorbents were removed from the gas stream by the baghouse.

The overall objectives of this project are to demonstrate the operation of the TOXECONTM multi-pollutant control system and:

1. Achieve 90% mercury removal from flue gas through activated carbon injection (achieved).

2. Reduce particulate emissions through collection by the TOXECONTM baghouse (achieved).

3. Maintain 100% utilization of fly ash collected in the existing electrostatic precipitator (achieved).

4. Demonstrate reliable, accur ate mercury CEM suitable for use in the power plant environment (achieved).

5. Evaluate the potential for 70% SO 2 control and trim control of NO x from flue gas through sodium-based or other novel sorbent injec tion, while maintaining 90% mercury removal.

6. Recover 90% of the mercury captured in the sorbent.

Objective #5 was the focus of the test program described in this report.


## Background

Testing of SO 2 /NO x control sorbents to date in the TOXECONTM/COHPAC ® configuration included:

• Full-scale tests inje cting sodium bicarbonate and s odium sesquicarbonate (trona) upstream of the Big Brown COHPAC ® baghouse for SO 2 control. 1

• Pilot tests of sodium and lime sorb ents injected upstream of COHPAC ® for SO 2 control at Southern California Edison’s Mohave Station. 2

• Slipstream tests of sodium-based material s, lime, activated car bon, and a proprietary catalyst for NO x , SO 2 , SO 3 , HCl, HF, and Hg at the PSEG Hudson Generating Station. 3

Test results indicate that sodium-based products can achieve from 30% to 70% SO 2 reduction. At normal flue gas temperatures, lime/ca lcium products are not effective for SO 2 control. Sodium-based sorbents also reduced NO x by 10% to 20%. HCl removal was as high as 50% at Hudson using sodium sesquicarbonate.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

3 

## Test and Equipment Description

This test effort was designed to support the overall objectives of the TOXECONTM retrofit at Presque Isle as well as to fu rther the technical understanding of the TOXECONTM technology for both We Energies and the greate r industry. Parametric and c ontinuous tests were planned to assess the capability of trona injection upstream of the TO XECONTM baghouse to control SO 2 and NO x . Injection equipment and measurement instru mentation were installed specifically for these tests. The following were th e objectives of the testing program:

1. Quantify the trona injection rate versus SO 2 /NO x removal.

2. Record baghouse performance over the te st period, showing how pressure drop, cleaning frequency and me rcury removal change.

3. Determine if there is any negative eff ect of trona injection on emissions (NO 2 production).

4. Evaluate the technical and economic performa nce of trona as an option for full-scale SO 2 control.

The tests for SO 2 /NO x control were conducted in two phases, baseline and parametric testing, as shown in Table 1. Measurements were taken during July to determine baseline conditions. Parametric testing data was used to characte rize the performance of trona across a range of injection concentrations and at different PAC injection concentrations. Originally, a 5 day continuous test was scheduled but due to shipping and material handling issues this phase was cancelled.

Table 1. Schedule of Activities for SO 2 /NO x Control Testing.

SO 2 -NO x Control Activity Duration (Days) Start Date Boiler Load
Baseline Testing 21 07/09/2007 Normal Operation Equipment Installation and Shake down 2 07/30/2007 Normal Operation Parametric Testing 10 08/1/2007 Full Load 6AM–6PM

The final test plan for in jecting trona to control SO 2 and NO x was distributed to the project team in July. The plant completed the installation of SO 2 and NO x analyzers at each of the three ducts upstream of the sorbent injection poi nt in early July. These analyz ers provided data on untreated SO 2 and NO x levels for both baselin e and injection testing.

Plant operators kept the three units at full, st eady load during the two week test period. The boiler soot blowers were used every hour on a sta ggered schedule with the th ree units to keep the flue gas temperature from fluctu ating during testing. PAC injecti on was left unchanged initially. The logic allowed for the injection rate to va ry +/- 20% to keep 91% mercury removal.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

4 

### Trona Background Information
Trona is a sodium-based, naturally occurring mi neral (sodium sesquicarbona te). The trona used during this test program was obtained from Solv ay Chemicals, Inc. and was mined in Green River, Wyoming. The purified SOLVAir Select 200 trona was shipped by rail to Chicago then loaded into hopper trucks for delivery to Mar quette, Michigan. The hopper trucks typically carried 45,000 – 48,000 lb of trona depending on the te st schedule. The particle size of the trona averaged 26 μm according to the Certificat e of Analysis accompanying the material.

The formula for sodium sesquicarbonate is:

Na 2 CO 3 . NaHCO 3 . 2H 2 O sodium carbonate . sodium bicarbonate . water

When heated to 257-482 o F in a duct or a calciner, the sodi um trona decomposes to sodium carbonate according to the formula:

2(Na 2 CO 3 . NaHCO 3 . 2H 2 O) → 3Na 2 CO 3 + CO 2 + 5H 2 O

When injecting trona into a coal fired power plant flue gas, it reacts with hydrochloric acid and SO 2 according to the following:

Na 2 CO 3 . NaHCO 3 . 2H 2 O + 3HCl → 3NaCl + 4H 2 O +2CO 2
2(Na 2 CO 3 . NaHCO 3 . 2H 2 O) + 3SO 2 → 3Na 2 SO 3 + 4CO 2 + 5H 2 O

3Na 2 SO 3 + 1.5O 2 → 3Na 2 SO 4
Review of industry literature empha sizes the benefit of injecting tr ona in a hot-side (greater than 700 °F) location. Trona experiences what is refe rred to as a “popcorn effect” where at high temperature the thermal decomposition reaction re sults in an expanded particle with a high surface area to mass ratio, improving the chemical availability of the sodium compound. This change improves the effectiveness by a factor of between 5 and 10. Trona will still react with SO 2 if injected at lower temperatures (typical cold-side temperature around 300 to 350 °F) but loses the reactivity otherwise gained by the pa rticle expansion. Consequently, for lower temperature applications more trona is required to achieve the same SO 2 removal efficiency. During the first 10 days of August, the flue gas entering the baghouse at Presque Isle varied from 333 – 372 o F.



### Trona Injection Equipment
The injection equipment for this test program wa s obtained from Bulk Co nveyor Specialist, Inc. and staged near the Units 7-9 st ack as shown in Figure 1. This equipment consisted of a trailer holding approximately 40 tons of trona and a sepa rate trailer housing the blowers and controls (Figure 2). This system injected sorbent at the sh ipped particle size. Feed rate for the trona was from 2,200 lb/hr up to 5,900 lb/hr at full load to cover a wide range of stoichiometric ratios.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

5 Figure 1. Staging Area for Trona Injection EquipmentTopical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

6 Figure 2. Trona Injection Tr ailer Blowers and Controls.

The trona was fed to three injection lances which were located downstream of the ID fan discharges, but upstream of the poi nt where the ducts combine. Each lance discharged sorbent into the center of its duct, wher e turbulent flow provided gas/sorbent mixing. The lances were located below the current PAC injection lances (w hite hose in Figure 3). This is downstream of the NO x analyzer probe used for boiler feedback.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

7 Figure 3. Injection Ports



### Trona/Ash Unloading Issues
Prior to field testing, there was some concern that the reacted trona/a sh/PAC from the baghouse would be difficult to unload and transport us ing the existing ash-handling equipment. The reacted trona hardens when wetted, and Presque Isle typically uses a wet unloader for the PAC/ash mixture. This mixture is th en hauled by truck to the landfill.

Benetech, Inc. performed a series of laborator y tests on the anticipated final product from the baghouse and developed a chemical to prevent hard ening of the mixture. A tanker truck of the chemical along with injection equipment was pr epared and shipped to Presque Isle for the testing. Provisions were made to add this chemical to the water spray used in the wet unloader.



### SO 2 

### , NO x 

### and Opacity Measurement

SO 2 and NO x monitors were installed on a temporary ba sis by We Energies ne ar the exit of the ID fan on each duct to establish baseline levels co ming from each boiler. At the stack, the plant continued to utilize the installed SO 2 and NO x monitors to establish native removal across the TOXECONTM system and provide rem oval rates during trona injection.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

8 Data from the inlet and stack monitors was colle cted continuously by th e plant data acquisition system (EDS) and saved on the historian com puter. The data was downloaded every week during baseline and every da y during trona injection.

Prior to the trona inj ection testing, three Rela tive Accuracy Test Audits (RATAs) were performed on the SO 2 and NO x monitors in the Units 7, 8, and 9 flues. The Unit 7 RATA was performed on June 13, 27, and 28, 2007. The Unit 8 RATA was performed on June 5 and 6, 2007. The Unit 9 RATA was performed on June 5 and 6, 2007.

The results of the RATAs reporte d by the testing company were: “The test results from this test progr am indicate that each CEM system meets the United States Environmental Protection Agency (USEPA) annual performance specification for relative accu racy as published in 40 CFR Part 60 and/or 40 CFR Part 75.”



## Test Results

Baseline Testing
The purpose of the baseline test was to establish the concentrations of pol lutants leaving the air preheater and to determine if there was any nati ve capture across the TOXECONTM fabric filter without sorbent injection. Figure 4 shows inlet and outlet data for SO 2 and NO x for the three ducts and flues during July. As expected, none of the three graphs show any removal across the baghouse prior to trona injection. In addi tion to the flue gas measurements for SO 2 /NO x , ash samples were taken from the baghouse hoppers. A composite sample of ash from four hoppers was used to characterize the ash during this time.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

9 Unit 7 Baseline SO2 and NOx

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

7/2/07 7/7/07 7/12/07 7/17/ 07 7/22/07 7/27/07 8/1/07

TimeRate (lb/MMBtu)

SO2 Inlet
SO2 Outlet
NOx Inlet
NOx Outlet

Unit 8 Baseline SO2 and NOx

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

7/2/07 7/7/07 7/12/07 7/17/07 7/22/07 7/27/07 8/1/07

TimeRate (lb/MMBtu)

SO2 Inlet
SO2 Outlet
NOx Inlet
NOx Outlet

Unit 9 Baseline SO2 and NOx

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

7/2/07 7/7/07 7/12/07 7/17/ 07 7/22/07 7/27/07 8/1/07

TimeRate (lb/MMBtu)

SO2 Inlet
SO2 Outlet
NOx Inlet
NOx Outlet

Figure 4. Baseline SO 2 and NO x DataTopical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

10 

### Parametric Testing

Schedule and Materials Handling The trona injection equipment was set up at Pr esque Isle on Monday, July 30, 2007. All of the injection hoses and lances were installed by late afternoon. El ectricity was connected to the blower trailer by 3:30 pm.

The first truckload of trona arrived on site Tuesday morning. This truck carried 48,000 lbs, which partially filled the hopper truck. In order to test the wet unloader and the effect of the anti-setup chemical supplied by Benetech, four h ours of injection at 2,200 lb/hr was performed on Tuesday, July 31. At the end of the four hours, the ash silo was unloaded using the chemical in the water feed to the pin mixer. The ash silo had been unloaded ear lier in the day so the majority of the ash in the silo contained reacted trona.

There were no problems with hardening or settin g up of the reacted trona /ash/PAC in the wet unloader or in the ash truck. Benetech also prov ided 10 gallons of a “trona release chemical” for spraying on the inside of the ash truck bed and th e inside of the pin mixer. Bottom ash from Units 5 and 6 (bituminous coal) was used to line the bottom of the ash truck also since the efficacy of the release chemical or anti-setup chem ical had not been tested at full scale yet. Figure 5 shows the material being unloaded at th e landfill. The consistency was similar to wet sand. The next day the material sti ll had not changed in consistency.

Figure 5. Unloading Reacted Trona/PAC/Ash MixtureTopical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

11 On Wednesday morning, August 1, the ash silo was unloaded to remove the accumulated material from overnight. This material contai ned significant amounts of reacted trona that had been cleaned from the bags over the course of several hours af ter injection had stopped. This unloading process was inadvertently performed w ithout the anti-setup chem ical, and there were no problems with the material setting up in either the mixer or the truck. Over the course of the next few days, unloading at the end of injection was done with th e chemical, and in the morning without. There were no issues with setup eith er with or without th e chemical. The wetted material showed a significant heat of reacti on and was still steaming when unloaded at the landfill.

During the second week of testi ng, the ash silo was unloaded afte r injection using water only (no anti-setup chemical). Although there was a noti ceable heat associated with the mixing, the material didn’t set up in the pin mixer or in the truck. A sample was taken at the landfill and the next day it still hadn’t set up. Th e reaction with water to form a solid hydrate may have occurred in the pin mixer but the action of the mixer may have kept the material from solidifying. The main risk of wetting the trona/ash /PAC without the anti-setup chemi cal is that if the mixer stops, the wet material in the mixer would likely so lidify and would be very difficult to remove.

Parametric testing began August 1, 2007. During this test phase all three units were at full load. The original plan was to vary the sorbent injection rate fr om approximately 2,200 lb/hr up to 5,400 lb/hr. There was some concern that the as h system could not hand le a sorbent injection rate above 5,400 lb/hr. The vacuum system used to pull ash from the hoppers and transport it to the silo was rated for 5,000 lb/hr. Addi ng the ash and PAC (110 lb/hr and 130 lb/hr approximately) put the highest in jection rate well above the ra ting for the vacuum system.



### SO 2 

### and NO x 

### Removal Table 2 shows the injection rate and SO 2 removal for the test period. The maximum removal achieved during the testing was 74.1% when co-injecting 3.8 lb/MMacf PAC.

Table 2. Trona Injection Results.

Date Trona Injection Rate (lb/hr) Average NSR* SO 2 Inlet (lb/MBtu) SO 2 Removal (%) Comments

8/1/07 2223 0.37 0.50-0.66 46.6 8/2/07 2223 0.41 0.48-0.63 47.6 8/3/07 4446 0.81 0.48-0.59 65.4 8/4/07 4446 0.79 0.50-0.58 65.5 8/5/07 5432 0.97 0.49-0.57 69.8 8/6/07 5926 - - - Difficulty feeding trona – test stopped 8/7/07 5926 1.02 0.52-0.60 70.7 8/8/07 5926 1.02 0.52-0.66 68.5 PAC injection turned off during am 8/9/07 5926 1.03 0.49-0.62 72.1 PAC injection ramped up to 3.8 lb/MMacf 8/10/07 5926 1.02 0.51-0.64 74.1 Started PAC injection at 3.8 lb/MMacf at start of trona injection * Normalized Stoichiometric RatioTopical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

12 As seen in Table 2 and Figure 6 below, the best SO 2 removal was observed when PAC was being injected at an unusually hi gh level for this site (3.8 lb/MM acf). This was done to try to recover the >90% mercury removal. This PAC inj ection rate was at the e nd of a test day, and the mercury removal was at 89%. During all trona in jection tests, mercury removal degraded, and then slowly recovered overnight when no tr ona was injected (discussed below).

SO2 Removal Using Trona

40 45 50 55 60 65 70 75 80

0 1000 2000 3000 4000 5000 6000 7000
Trona Injection Rate (lb/hr)SO2 Removal (%)

PAC Injection Off

PAC Injection at 3.8 lb/Mmacf

Figure 6. SO 2 Removal vs. Trona Injection Rate.

Figure 7 shows typical SO 2 removal profiles at varying trona inje ction rates. There was an initial rapid increase in removal but it took 3-4 hours before removal became somewhat steady. Most test periods were 8 hours, but one day was only 6 hours. When trona injection was turned off, there was an initial rapid decrease in SO 2 removal, but it didn’t come back to baseline levels for 5-6 hours, which was the time required to pe rform a full cleaning cycle on the baghouse.

SO2 Removal Using Trona

0 20 40 60 80 100

0 2 4 6 8 10 12 14 16 Time (hr)Removal (%) 2223 lb/hr 4446 lb/hr 5432 lb/hr 5926 lb/hr 5926 lb/hr high PAC

Figure 7. SO 2 Removal Profiles.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

13 In addition to the impacts on SO 2 , a small reduction in NO x emissions was expected based upon work at other test sites. As shown in Figure 8, there was no noticeable reduction in NO x .

NOx Removal Using Trona 5926 lb/hr

-10

-5 0 5 10 15 20

0 2 4 6 8 10 12 14

Time (hr)Removal (%) Trona Injection Began

Trona Injection Stopped

Figure 8. NOx Removal During Trona Injection.

At other test sites, a side reaction from using trona is th e creation of small amounts of NO 2 , which results in a brownish plume and an increas e in opacity. Figure 9 shows an increase of about 0.75% in the three opacity monitors during the highest inj ection rate used. There was no visible brown plume during this test.

At the end of the trona injection period on August 7, PAC injection was also turned off and kept off overnight and through the start of trona injection on August 8. At mid-day on August 8 a brownish plume was seen coming from the stack. Th is is the first time this had occurred. The opacity levels on all three monitors increased by almost 3% (Figure 10) . PAC injection was resumed at 1:00 pm and within 30 minutes the pl ume had been visibly reduced and the opacity decreased.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

14 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

9:00 12:00 15:00 18:00 21:00 0:00 3:00SO2 and NOx (lb/MMBTU)

0 10 20 30 40 50 60 70 80Removal (%) Unit 9 Inlet (SO2) Unit 9 Outlet (SO2) Unit 9 Inlet (NOx) Unit 9 Outlet (NOx) SO2 Removal NOx Removal

0 0.5

1 1.5

2 2.5

3 3.5

4 4.5

5

9:00 12:00 15:00 18:00 21:00 0:00 3:00Opacity (%) Flue 7 Opacity Flue 8 Opacity Flue 9 Opacity

Figure 9. Effect of 5926 lb/hr Trona Injection on SO 2 , NO x , and Opacity.

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

3:00 6:00 9:00 12:00 15:00 18:00 21:00SO2 and NOx (lb/MMBTU)

0 10 20 30 40 50 60 70 80Removal (%) Unit 9 Inlet (SO2) Unit 9 Outlet (SO2) Unit 9 Inlet (NOx) Unit 9 Outlet (NOx) SO2 Removal NOx Removal

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0

3:00 6:00 9:00 12:00 15:00 18:00 21:00Opacity (%) Flue 7 Opacity Flue 8 Opacity Flue 9 Opacity

Figure 10. Effect of 5926 lb/hr Tron a Injection without PAC InjectionTopical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

15 

### Baghouse Pressure Drop and Cleaning Frequency Any impacts on the cleaning cycle and pressure dr op were closely monitored. The fabric filter was cleaned in an online mode for all parametric tests. Figure 11 shows the effect of trona injection on baghouse operation dur ing the entire injection period. As mentioned earlier, mercury removal was negatively a ffected during trona injection, but recovered overnight. The air-to-cloth ratio didn’t change during testing. The cleaning fre quency increased slightly during testing.

One unexpected side effect due to trona injec tion into the baghouse was degradation in mercury removal. On August 9, the PAC injection was in creased throughout the trona injection period to try to recover 90% mercury removal. By the e nd of the injection period, PAC injection was at 3.8 lb/MMacf and mercury removal was at 89%. On August 10, PAC injection was increased to 3.8 lb/MMacf at the start of trona injection and there was still a reduction in removal initially. PAC injection reached 4.6 lb/MMacf without rega ining 90% mercury removal. Previous tests show an initial drop in removal, then a partial recovery afte r several hours.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

16 0 1 2 3 4 5 6 7 8 9 10

7/27/07 8/1/07 8/6/07 8/11/07Hg (ug/m3)

0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375

7/27/07 8/1/07 8/6/07 8/11/07Total Boiler Load (MW)Temperature (F)

0.0 0.5 1.0 1.5 2.0 2.5Gas Flow Rate (MMacfm)

0 1 2 3 4 5 6 7

7/27/07 8/1/07 8/6/07 8/11/07Pressure Drop (inches H2O)

0 1 2 3 4 5 6

7/27/07 8/1/07 8/6/07 8/11/07A/C Ratio (ft/min)Trona Injection Rate (k#/hr)

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0Clean Frequency(pulses/bag/hr)

Trona Injection

0 10 20 30 40 50 60 70 80 90 100

7/27/07 8/1/07 8/6/07 8/11/07Hg Removal (%)

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5PAC Injection Conc.(lb/MMacf) Hg Outlet Hg Inlet

PAC Injection Baghouse Inlet Temp

Hg Removal Fl-Fl Pressure Drop

Compartment 1-5 Pressure Drop

Cleaning Frequency Compartments 1-5 Flue Gas Volume Total Boiler Load

A/C Ratio

Figure 11. Baghouse Operation Du ring Trona Injection Testing.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

17 

## Economic Assessment of Full-Scale Trona Injection

Introduction
An economic assessment was performed to determ ine the cost for the installation and operation of a full-scale, commercial trona injection syst em at We Energies’ Presque Isle Power Plant Units 7, 8 and 9. Based on the results from the tests described above, cost and design estimates were made for a permanent trona injection system . The design premises and the results of the economic analysis are presented here. A detail ed description of the economic analysis is presented in Appendix A.

Estimates were made for sorbent usage and costs were estimated for three injection rates of 2223 lb/hr, 4446 lb/hr, and 5926 lb/hr, which include tr eatment for the flue gas from all three units. From the tests completed in August 2007, these injection rate s correlate to SO 2 removal rates of approximately 45%, 64%, and 70%. The cost and design of process equipment has been estimated based on the test results for up to 70% SO 2 control and on the plant-specific requirements such as sorbent storage capacity, plant arrangement, sorbent transportation and delivery options, retrofit issues, controls interface, etc.

A consequence of simultaneously injecting trona for SO 2 control and injecting PAC for mercury control was significant degradation in mercury removal. August 2007 tests showed an initial drop in mercury removal, then a partial recovery after several hours. This economic assessment includes cost estimates for the increase of PAC usage required when injecting trona. Normal average injection rates at Pres que Isle of PAC for 90% mercur y removal were 1.5 lb/MMacf for DARCO ® Hg-LH and 2.5 lb/MMacf for DARCO ® Hg. To achieve 90% mercury removal while injecting trona at a ra te required for 70% SO 2 removal, DARCO ® Hg-LH would need to be injected at approximately 4.5 lb/MM acf and the injection rate for DARCO ® Hg was assumed to be at 7.5 lb/MMacf, based on th e required increase in DARCO ® Hg-LH usage.. The increased requirement for PAC was not measured at the lowe r trona injection rates. The PAC increase was calculated based on a linear increase from baseline to the highest injection rate. PAC injection rates costs for the SO 2 removal rates are summarized below in the section regarding variable operating costs in Appendix A.



### Process Design

Trona Injection System Costs were estimated for two different equipment setups. The first set up consists of one bulk storage silo with three pneumatic conveying syst ems. The second setup consists of three bulk storage silos, each dedicated to a single unit w ith one pneumatic conveying system on each silo. Note that the silo size is the same (150,000 lbs tr ona/silo) for the one- and three-silo systems. The three-silo setup is the type that is installed at Mirant’s Potomac Station.

The conveying distances and the storage site were assumed to be the same as the test in August 2007. The silo was sized based on the capacity to hold approximately one day worth of trona at the maximum design injection rate of 6,000 lb/hr. This would be approximately 4 truckloadsTopical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

18 (40,000 lb) or one rail car load (200,000 lb) for th e combined 3 units. The issue of material packing in the silo and inhibiting the flow-ability of the material was considered in the sizing of the silo. The 3-silo option outlined in the tabl es below would provide the plant with a 3-day supply of trona. Table 3 displa ys the design criteria for an SO 2 control system.

Table 3. System Design Criteria for SO 2 Control System at Presque Isle (6000 lb/hr injection, >70% SO 2 control).
Parameter 3-Silo System 1-Silo System

Number of silos 3 1 Number of injection trains 3 3 Design feed capacity/train (lb/hr) 2000 2000 Total trona storage capacity (lbs) 450,000 150,000 Conveying distance (ft) 300 300

Sorbent Trona Trona Aerated density (lb/ft 3 ) 49 49 Settled density (lb/ft 3 ) 69 69 Particle MMD (microns) 26 26

The trona can be delivered by two methods. One option is to have the trona railed to nearby Ishpeming in 200,000-lb capacity rail cars and then tran sferred to self-unloading pneumatic bulk tanker trucks and delivered in 40,000 -lb batches. Another option is have a rail spur installed to the plant and have rail cars direc tly unload to the storage silo(s). Both options have been cost estimated; however, the cost for a rail spur was not included.

The silo is equipped with a bin vent filter to contain dust during the unloading process. The silo is a shop-built, dry-welded tank with leve l indicators and load ce lls to monitor sorbent level and inventory. If only one silo is used, then that silo will have three hopper cones with a blower for each cone. If three silos are used, then each silo will have one hopper and blower.

The sorbent is fed from the hopper(s) by rotary va lves into the conveying lines. The conveying air is supplied by blowers. The air provides suction to draw the sorbent into the conveyer piping and carries it to the injection la nces where it is dispersed into the duct. There are three injection lances, which are located downstream of the ID fan discharges, but upstream of the point where the ducts combine. Each lance discharges sorben t into the center of it s duct, where turbulent flow will provide gas/sorbent mixing. The la nces will be located below the current PAC injection lances. This is downstream of the NO x analyzer probe used for boiler feedback. Figure 12 shows the schematic of the plant and includ es the two options fo r the trona silo(s).Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

19 ESP APH

TOXECON BAGHOUSE ESP APH

ESP APH PAC SILO

THREE TRONA SILOS Unit 9

Unit 8

Unit 7

SINGLE TRONA SILO-ORFigure 12: Schematic of the Trona Injection Equipment at Presque Isle Units 7, 8 and 9



### Ash Handling System Some modifications and upgrades to the existing plant equi pment would be required to accommodate a full-scale trona injection system. Th ese include upgrades to the electrical supply to provide new service to the injection system as well as intercom phones and area lighting.

The spent trona/ash/PAC mixture will be collected in the baghouse, conveyed to the ash silo and unloaded into ash trucks that dispose of the mate rial in the landfill as is the current operating procedure. The ash handling capacity will need to be increased to accommodate the higher loading of material. The existing 4 in. conve yor piping system is adequate although a new mechanical exhauster capable of up to 15 in Hg will need to be installe d. The new mechanical exhauster motor size would need to be increased from 10 HP to 20-25 HP.

The increased vacuum level produced by a new mech anical exhauster increases the gas flow rate in the ash system and therefore creates a larger air- to-cloth ratio in the filter separator. An air-tocloth ratio of 4:1 is desirable so an increased f ilter area would be require d with trona injection. To achieve this ratio the existing filter/separat ors could be operated in parallel, however this leaves the system without a redundant filter/separa tor. Another option is to replace the existing filter/separator with two larger capacity, continuous operating, filter/separators. Modifications to the ash silo building would be necessary, such as extending the bin roof and modifying the bin structure to support the higher load ings of the bigger filter/separat ors. An alternative would be to install pleated bags in the existing system.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

20 

### Cost Estimates and Results

Costs for capital equipment, operations, mainte nance, and power were provided by vendors as well as estimated using the economic basis provided in EPRI’s Economic Evaluation of DryInjection Flue Gas Desulfurization Technology 6 . The capital and fixed and variable O&M costs were then converted into and combined as 20-y ear levelized costs using the traditional EPRI Levelized Cost or Uniform Annual Cost analysis typical of historical EPRI studies and as used in Reference 6. This methodology provides a suita ble first-cut approximation and comparison of the time-value of money over th e 20-year estimated life of the trona injection system options considered.

Different scenarios of equipment set-up and inje ction rates were priced and compared. These scenarios and the economic analysis results are su mmarized below. A more-detailed description of the analysis is presented in Appendix A.



### Capital Costs The costs of equipment and installation for the trona injection system and balance-of-plant systems are shown in Table 4. This table compares the capital cost elements for the one-silo vs. three-silo systems. Capital costs for a perman ent trona injection system include the storage silo(s), blowers, conveyor piping, dehumidifiers, and modifications to the ash handling system. Bulk Conveyor Specialist, Inc provided the cost estimates for the trona storage and injection equipment and installation. The required capi tal equipment is summarized below. A moredetailed description of th ese capital cost elements is presented in Appendix A.

• Storage Silo : Skirted, carbon steel shell with cone. Stor age capacity of 75 tons. Includes bin vent collector, bin discharger, discharge valve, bin indicat ors, weigh hopper, rotary valves, control panel, blowers, dehumidifiers.

• Blowers

.

• Conveyor Piping

.

• Lances

.

• Housing for Redundant Blowers and Dehumidifiers

.

• Mechanical Exhauster Package

• Larger Capacity Filter/SeparatorTopical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

21 Table 4: Summary of Equipment, Bala nce-of-Plant, and Engineering Costs Trona Injection System and Balance-of-P lant Equipment and Installation Costs Presque Isle Power Plant Units 7, 8, and 9 COST CAPITAL COST ELEMENT DESCRIPTION 1 Silo 3 Silos Trona Storage/Injection System (Equipment Cost)

• Silo (s) - Including: $ 595,000 $ 1,785,000 75 ton Capacity Storage Silo, 1 Hopper Below Silo, 1 Blower, 1 Dehumidifier Pkg, Conveyor Piping (300 ft)

• Lances (*Injection lances from test can be used in permanent system; additional lances are optional at $5,000 per lance) $ 5,000* $ 5,000*

• Redundancy (equipment added for 3 injection lines per 1 silo), Including: $ 98,500 $ -

Splitter Valve, 2 Hoppers, 2 Rotary Valves, 2 Blowers, 2 Dehumidifier Packages, Housing for Blowers and dehumidifiers Installation of Trona Storage/Injection Equipment $ 580,000 $ 580,000 Includes civil, electrical, m echanical and piping TOTAL PROCESS EQUIPMENT $ 1,273,500 $ 2,365,000

Increase In Ash Handling Capabilities

• 2 Mechanical Exhauster Packages $ 15,000 $ 15,000

• Larger Capacity Filter/Separator (Design and Supply) $ 200,000 $ 200,000 TOTAL ASH HANDLING EQUIPMENT UPGRADES $ 215,000 $ 215,000 TOTAL EQUIPMENT COSTS (Install ed Cost, TEC) $ 1,488,500 $ 2,580,000

General Facilities (10% of TEC) $148,850 $258,000 Engineering and Home office Fees (12.5% of TEC) $186,062 $322,500 Project Contingency (25% of Process Equip. + 20% of Ash Handling Equip.) $361,375 $634,250 Process Contingency (7.5% of Process Equip. + 5% of Ash Handling Equip.) $106,262 $188,125 TOTAL PLANT COST (TPC) $2,291,050 $3,982,875 Preproduction Costs (=(1/12)*(Fixed O&M + Var O&M)+.02*TPC) $397,921 $431,757 TOTAL CAPITAL REQUIREMENT (TCR) $2,688,971 $4,414,632

As shown in Table 4, the total capital require ment (TCR) for a project includes not only the capital cost estimates provided by the vendor, but also such fact ored estimates as funds for general facilities, engineering and home office fees, project a nd process contingencies, and preproduction costs. These factored estimates were calculated in accordance with EPRI guidelines and are consistent with those factors us ed in the analysis in Reference 6 as shown in the table. The TCR for a three-silo system is about 1.6 times that for a one-silo system.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

22 

### Operating and Maintenance Costs The operating and maintenance (O&M) costs associated with trona injection for SO 2 control include fixed and variable costs. Fixed O&M costs include labor, maintenance materials, and administrative and support labor. The variable O&M costs vary depending on unit and other capacity factors and include sorben t, power, and waste disposal.

Fixed O&M Costs
The fixed O&M costs include:

• labor costs for ash handling

• operating and maintenance la bor costs for the silo and injection equipment

• maintenance materials

• administrative and support labor

The maintenance labor, materials and support labor are estimated using known costs for the TOXECON system installed and operating at Presque Isle.

Applicable labor rates, maintenance, and opera ting materials costs were determined for three SO 2 removal rates (45%, 64%, and 70%). For ex ample, the ash handling system labor costs increase as SO 2 removal rates increase due to the need for more frequent ash unloading and disposal because of the increased sorbent injection rates. Operating labor co sts also vary slightly depending on the type of PAC used due to slight differences in injection rate.

The operating labor costs for the silo and inje ction equipment are constant for different SO 2 removal rates as well as constant with either one-silo or three-silo systems. The operating, maintenance and project overhead costs are estima ted from the annual costs associated with the TOXECON system currently at Presque Isle. Th e maintenance materials are estimated in the

same manner.

Table 5 summarizes the first-year fixed O&M cost s calculated for this analysis. As seen, the Fixed O&M costs do not vary depending on whethe r a one- or three-silo system is used. However, costs do vary depending upon the type of sorbent used and on the SO 2 removal rate. Table 5 shows the total first year fixed O&M costs comparing costs at different SO 2 removal
rates.

Note that these first-year O&M costs in Table 5 can also be expressed in terms of $/yr, although such numbers do not reflect the application of le velization factors to reflect the time-value of money. Levelized O&M and capital costs are discussed below. The development of these fixed O&M costs and the assumptions made are de scribed in more detail in Appendix A.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

23 Table 5. Total First-Year Fixed Operating & Maintenance Costs
Total First Year Fixed O&M Cost 1 or 3 Silos SO 2 Removal Rate O&M Labor & Material Costs* 45% 64% 70%

• Labor Costs for Ash Handling Trona + DARCO ® Hg + Ash $132,740 $265,880 $357,860 Trona + DARCO ® Hg-LH + Ash $126,470 $256,800 $345,500

• O&M Labor & Materials & Support Labor for Silo & Injection Equipment O&M Labor Costs $360,000 $360,000 $360,000 Maintenance Materials $108,000 $108,000 $108,000 Total First Year Operating, Maintenance, & Support Costs (Silo & Injection) $468,000 $468,000 $468,000
T OTAL O&M COSTS, 1 or 3 SILOS

(Trona + DARCO ® Hg + Ash) $600,740 $733,880 $825,860

T OTAL O&M COSTS, 1 or 3 SILOS

(Trona + DARCO ® Hg-LH + Ash) $594,470 $724,800 $813,500
*PAC injection rate varied for each SO2 removal rate.

Variable O&M Costs The variable O&M costs vary depending on unit a nd other capacity factors and include estimates for:

• Power Costs

• Sorbent Costs

• Landfill Costs

The sorbent costs include trona as well as th e increased PAC needed to keep the mercury removal at 90%. Power costs were estimated from the equipment power requirements and the current busbar cost of power production as obtained from the utility.

Power Costs The electrical requirements for the trona injection system incl ude power for blowers, rotary valve motors, bin discharger, and dehumidifiers. Each injection system requires power for one blower, one dehumidifier, and one rotary valve. There is one bin discharg er per silo. Therefore, for a one-silo system with one large silo, power fo r one discharger is need ed. For a three-silo system, power for 3 dischargers is needed. The long-term running power required is roughly half of the power required for start-up (connected load). The system power in kW is calculated knowing the amperage and voltage needed for the different components, along with a power factor and knowledge of the estimated time that each component operates.

Table 6 summarizes the estimated variable first- year operating cost for power estimated for oneand three-silo injection systems by summing th e power usage requirements for each component and using an assumed busbar cost to produce power of $0.03/kWh as estimated by the utility. The calculations and intermediate steps used to determine the power cost estimate are presented in more detail in Appendix A.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

24 Table 6. Variable First-Year Operat ing & Maintenance Costs for Power
Variable O&M Costs: Power 1 –Silo System 3-Silo System Power Usage, in kW 42.35 127.05 Unit Power Cost, in $/kWh $0.03 $0.03 Power Cost, in $/yr $11,125 $33,375

Sorbent Costs Sorbent costs vary depending on the desired SO 2 removal percentage and on the delivery method. Costs for trona and PAC increase as SO 2 removal levels increase due to the need for higher sorbent injection rates; this includes the increased trona injection rate as well as the increased PAC injection rate to maintain mercury re moval levels. The cost for trona to be railed directly to the plant is $140/t on assuming the costs to install a rail spur is picked up under another project. If a rail spur is not installed to the plant, the trona can be railed to Ishpeming, then loaded into a truck from there and delivered to the plant by truck. Using a combination of rail and truck would cost $155/ton.

The amount of PAC needed to maintain 90% me rcury control increases as trona injection increases due to the interference of trona injec tion with the PAC’s ability to capture mercury. Table 7 summarizes the sorbent costs for the two delivery methods for the three SO 2 removal rates of 45, 64 and 70%. Also reflected in the tabl e are the effects on first-year sorbent costs of different unit costs, and injection rates for trona and the PAC mercury sorbent, whether DARCO ® Hg or DARCO ® Hg-LH. The unit costs and inject ion rates assumed for each sorbent, delivery method and for each SO 2 removal rate as well as the steps taken to arrive at the total values summarized in Table 7. Additional details are provided in Appendix A.

Table 7. First-Year Variable Operating & Ma intenance Costs for Sorbent Delivered by Rail and by Rail/Truck Combination to the Plant Variable O&M Costs: Sorbent Delivered By Rail* or Combination to Plant SO 2 Removal Rate Sorbent Costs in $/yr** 45% 64% 70% Delivered by Rail* to Plant Trona + DARCO ® Hg $1,405,651 $2,836,597 $3,887,797 Trona + DARCO ® Hg-LH $1,460,182 $2,934,162 $3,920,647 Delivered by Rail† and Truck† Trona + DARCO ® Hg $1,514,056 $3,053,407 $4,178,520 Trona + DARCO ® Hg-LH $1,568,587 $3,150,972 $4,211,370

* Trona rail spur assumed to be installed under separate project ** Minus PAC that would already be injected † Trona railed to Ishpeming and trucked to plant

Waste Disposal Costs The variable O&M costs for waste disposal are the costs required to la ndfill the spent sorbent captured in the baghouse. The 2007 unit cost to landfill material was $44.40. The unit cost forTopical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

25 landfill along with the waste product ion rates for each sorbent was used to calculate the total cost to landfill the waste for both PAC sorbents for each of the three SO 2 reduction rates as summarized in Table 8. Since this is a differential cost estimate that cons iders only the effect of adding a trona injection system, the costs do not re flect the ash and PAC waste that is disposed of while running at full load with no trona inje ction. The waste production rates and steps used in calculating the waste disposal costs summari zed in Table 8 are shown in more detail in Appendix A.

Table 8. First-Year Variable Operating & Ma intenance Costs for Landfill Waste Disposal Variable O&M Costs: Waste Disposal SO 2 Removal Rate Waste Disposal Costs, in $/yr** 45% 64% 70% Trona + DARCO ® Hg $336,780 $674,575 $907,940 Trona + DARCO ® Hg-LH $330,360 $661,010 $886,060

**minus PAC/Ash waste that would already be disposed of

Total Variable O&M Costs
Table 9 shows the total variable O& M costs at the three different SO 2 removal rates and for the different delivery methods. The total O&M cost s include costs for power , sorbent usage, and disposal costs.

Table 9. First-Year Total Variable Operating & Maintenance Costs
Total Variable O&M Costs SO 2 Removal Rate Total Variable O&M Costs, $/yr 45% 64% 70%

Trona Delivered by Rail to Plant Trona + DARCO ® Hg $1,775,800 $3,544,550 $4,829,115 Trona + DARCO ® Hg-LH $1,823,915 $3,628,550 $4,840,085 Trona Delivered by Rail/Truck Trona + DARCO ® Hg $1,884,210 $3,761,360 $5,119,840 Trona + DARCO ® Hg-LH $1,932,320 $3,845,360 $5,130,810



### Levelized Costs Levelized costs were computed to represent a co nstant cost value for the operating and capital costs over the lifetime of the equi pment and project. In other words, the levelized costs take the present value of the net costs and spread them evenly over a period of time. This makes it possible to compare costs looking into the futu re. For this assessment levelized costs are presented in units of mills/kWh, where a mill is 1/1000 of a dollar.

The key economic parameters and factors used in this analysis are summarized in Table 10. The calculations to determine leve lized costs assumed a discount rate of 7.5% and a 20-year levelization factor was used. Th e capital costs are converted usi ng a fixed charge rate of 15.0%Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

26 and the O&M costs are converted using levelization factors of 1.29 for all costs including power and consumables.

Table 10. Economic Factors and Parameters
Economic Factors & Parameters Year of Estimate 2007 Plant Life 20 Years Capital Recovery Factor 0.15 Fixed Charge Rate 15% O&M Levelization Factor 1.29 Normal Capacity Factor 0.75 Power Capacity Factor 0.85

This methodology is consistent with typical historical EP RI studies, and in particular, the factors used here reflect those used in Reference 6. The use of a 15% Fixed Charge Rate is consistent with using a Capital Recovery Factor of 0.15, a typical approxima tion currently used by EPRI and utilities today for leveliz ing capital costs. Although the factors used here are generalizations, their use is a reasonable approximation for a first-cut economic evaluation for the rough comparison of these similar options. Sh ould any utility desire to pursue these options more seriously for a given plant, a detailed economic analysis using economic factors and a methodology specific to the utility ’s current normal practice woul d be advised to confirm the economic viability of each option.

Levelized Capital Costs The calculations used to determine levelized cap ital costs are shown in detail in Appendix A. Table 11 summarizes the levelized total capital re quirement for the one- and three-silo options. The total capital requirement fo r three silos is less than double the requirement for one silo.

Table 11. Levelized Capital Costs Levelized Capital Costs (20 yr, Current $ Basis) LEVELIZED TOTAL CAPITAL REQUIREMENT 1-Silo System 3-Silo System

Levelized $/yr $403,345 $662,195 Levelized $/kW $1.49 $2.45 mills/kWh 0.23 0.37

By comparison, the total capital requirement for a green-field in stallation of a pulse-jet baghouse on a 250 MW unit might cost approximately 50 $/ kW as suggested by an EPRI study published in 1992. 7

Levelized O&M Costs The detailed steps in calculating levelized fi xed and variable O&M costs are discussed in Appendix A. Tables 12 and 13 summarize the levelized fixed and variable O&M costs, respectively, resulting from this analysis. These tables summarize the levelized costs for the two PAC sorbents versus the three SO 2 removal rates.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

27 Table 12. Total Levelized Fixed Operating & Maintenance Costs Levelized Total Fixed O&M Cost SO 2 Removal Rates Levelized Total Fixed O&M Costs 45% 64% 70%

Trona + DARCO ® Hg + Ash Levelized $/yr $774,950 $946,705 $1,065,360 Levelized mills/kWh 0.44 0.53 0.60 Trona + DARCO ® Hg-LH + Ash Levelized $/yr $766,870 $934,990 $1,049,415 Levelized mills/kWh 0.43 0.53 0.59

Recall that the variable O&M cost s are dependent not only on the SO 2 removal rate and type of PAC sorbent used, but also on the transportation m ode to the plant; i.e., whether the sorbent is taken to the plant directly by rail or whether the Rail/Truck combination is used. This is reflected in the levelized total va riable O&M costs given in Table 13.

Table 13. Levelized Total Variable Operating & Maintenance Costs Levelized Total Variable O&M Costs SO 2 Removal Rate Levelized Total Variable O&M Cost 45% 64% 70%

Trona Delivered by Rail to Plant

Trona + DARCO ® Hg Levelized $/yr $2,290,7 86 $4,572,466 $6,229,557 Levelized mills/kWh 1.29 2.58 3.51 Trona + DARCO ® Hg-LH Levelized $/yr $2,352,8 53 $4,680,826 $6,243,710 Levelized mills/kWh 1.33 2.64 3.52 Trona Delivered by Rail/Truck

Trona + DARCO ® Hg Levelized $/yr $2,430,6 29 $4,852,150 $6,604,588 Levelized mills/kWh 1.37 2.74 3.72 Trona + DARCO ® Hg-LH Levelized $/yr $2,492,6 95 $4,960,510 $6,618,742 Levelized mills/kWh 1.41 2.80 3.72

Total Levelized Costs Table 14 shows the total levelized costs, which in cludes the total variable O&M costs, total fixed O&M costs and total capital costs at three removal rates and for the two PAC sorbents for the two sorbent delivery methods. This is presented for the both the one- a nd three-silo systems.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

28 Table 14. Total Levelized Costs (Capit al and Fixed & Variable O&M Costs) TOTAL Levelized Costs SO 2 Removal Rate Total Levelized Cost (Capital and Fixed & Variable O&M Costs) 45% 64% 70%

1-SILO SYSTEM Trona Delivered by Rail to Plant

Trona + DARCO ® Hg mills/kWh 1.96 3.34 4.34 Trona + DARCO ® Hg-LH mills/kWh 1.99 3.39 4.34

Trona Delivered by Rail/Truck

Trona + DARCO ® Hg mills/kWh 2.03 3.50 4.55 Trona + DARCO ® Hg-LH mills/kWh 2.06 3.55 4.55

3-SILO SYSTEM Trona Delivered by Rail to Plant

Trona + DARCO ® Hg mills/kWh 2.10 3.48 4.49 Trona + DARCO ® Hg-LH mills/kWh 2.13 3.54 4.48

Trona Delivered by Rail/Truck mills/kWh 2.18 3.64 4.70 Trona + DARCO ® Hg-LH mills/kWh 2.21 3.70 4.70



### Removal Cost per Ton of SO 2 

### Removed The best way to compare SO 2 removal technologies is on the basis of $/ton of SO 2 removed. Table 15 shows the cost per ton of SO 2 removed using trona at full scale for the three SO 2 removal rates considered as compared for th e two PAC sorbent options and the two sorbent delivery options. These values are levelized over 20 years.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

29 Table 15. Removal Cost per Ton of SO 2 Levelized Total Cost per Ton of SO 2 Removed ($/ton) SO 2 Removal Rate No. of Silos, Delivery Method, and Sorbent 45% 64% 70%

1 SILO Trona Delivered by Rail to Plant

Trona + DARCO ® Hg $1,483 $1,780 $2,116 Trona + DARCO ® Hg-LH $1,506 $1,809 $2,115

Trona Delivered by Rail/Truck

Trona + DARCO ® Hg $1,543 $1,864 $2,219 Trona + DARCO ® Hg-LH $1,566 $1,893 $2,218

3 SILOS Trona Delivered by Rail to Plant

Trona + DARCO ® Hg $1,594 $1,858 $2,187 Trona + DARCO ® Hg-LH $1,617 $1,887 $2,186

Trona Delivered by Rail/Truck

Trona + DARCO ® Hg $1,654 $1,942 $2,290 Trona + DARCO ® Hg-LH $1,677 $1,971 $2,290

Inspection of Table 15 reveals that the gr eatest impact on the cost per ton of SO 2 removal is primarily due to the rate of sorb ent injection. Note that in a on e-silo system for both sorbents and both delivery methods, the cost typically in creases by a factor of about 1.4 to increase SO 2 removal from 45% to 70%. For a three-silo syst em, the capital required for the larger system becomes a more significant in total cost. Howeve r, the sorbent cost still dominates and the total cost per ton of SO 2 removed increases by a factor of about 1.35.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

30 

## Conclusions

The goal of 70% SO 2 removal was achieved during this tw o week test period when injecting 5926 lb/hr of trona. This corresponds to an aver age NSR of 1.02. The inlet concentration of SO 2 varied from 0.48-0.64 lb/MBtu. The highest removal was 74.1% with PAC injection at 3.8 lb/MMacf.

There was very little reduction in NO x during the test period. In addition, the effect of a side reaction, where NO is ox idized to produce NO 2 , was observed on one test day when PAC injection was turned off. This indicates that there is some conversion of NO to NO 2 , but not enough to measure on the stack NO x CEMs and considerably below the target of 30% reduction. The NO 2 level was high enough to be visible and cause an increase in opacity of almost 3%. On days when PAC injection was occurring, the opacity increased by a maximum of 0.75% but there was no visible plume.

Injection of trona for SO 2 control resulted in a decrease in mercury removal using activated carbon. This effect was seen every day that tr ona was injected. The mercury removal slowly recovered overnight to the pre-test level of >90%. On the last two days of testing, PAC injection was increased to regain the >90% removal rate. Test conditions did not allow sufficient time to achieve this target rate while injecting trona. An estimate of the requi red PAC is 3X the pretrona test rate.

Baghouse and tube sheet pressure drop increased during trona injection, causing an increase in cleaning frequency from 0.18 p/b/hr to 0.22 p/b/hr.

Plant operators kept the three un its at full, steady load during te sting. The boiler soot blowers were used every hour on a stagge red schedule to keep the flue ga s temperature from fluctuating during testing. Trona was injected near the PAC injection port, which should have resulted in excellent mixing with the flue gas before reach ing the baghouse. The trona injection had no effect on boiler operations.

The reacted trona, PAC, and ash were unloaded fr om the ash silo using a wet unloading system. Because sodium carbonate will react with water to form solid hydrates, an anti-setup chemical was initially used with the water during unloadi ng. No setup of the baghouse mixture was seen either in the mixer or in the transport truc k. During the first wee k, an unloading during the morning occurred without the chemical, also resu lting in no setup in the mixer or truck. The material may have been forming hydrates during mixing, preventing a hard setup. The use of the anti-setup chemical should be considered in futu re tests unless it can be shown that the mixing system prevents a solid setup in the mixer or truck.

An economic assessment of a full-scale trona in jection system included equipment and other capital costs along with sorbent cost (trona and increased amo unt of PAC to maintain 90% removal) and O&M costs. The cost to remove SO 2 varied from $1,483/ton at 45% removal and one silo to $2,290/ton SO 2 at 70% removal with 3 silos.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

31 

## References

1. EPRI Project Report number ADA4352002F01, March 1994.

2. EPRI Project RP 3083-05 Final Report (Mohave Pilot Tests), April 1996.

3. EPRI Project #TR-110867, “Assessing Air Pollu tion Control Options at the Hudson Station of Public Service Electric and Gas,” August 1998.

4. Standards of Performance for New Stationa ry Sources National Emission Standards for Hazardous Air Pollutants Addition of Me thod 29 to Appendix A of Part 60 and Amendments to Method 101A of Appendix B of Part 61 | Federal Register | USEPA 03- 08-2007

a. Federal Register document b. URL: http://www.epa.gov/EPA-AIR/1996/April/Day-25/pr-23270.html

5. Mirant Corporation, “Trona Injection Tests Mirant Po tomac River Station Unit 1 November 12 to December 23, 2005”, January 16, 2006.

6. Economic Evaluation of Dry-Injectio n Flue gas Desulfurization Technology , EPRI CS4373, EPRI Project 1682-1, January 1986.

7. Economic Evaluation of Particulate Cont rol Technologies, Volume 1: New Units , EPRI TR-100748, EPRI Project 3083-04-1, September 1992.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

32 

## APPENDIX A – Cost Estima tes and Results – Details

Costs for capital equipment, operations, mainte nance, and power were provided by vendors as well as estimated using the economic basis provi ded in EPRI’s “Economic Evaluation of DryInjection Flue Gas Desulfurization Technology.” The costs are broken into sections of capital costs, operating and maintenance costs, and all are converted to 20-year levelized costs. Different scenarios of equipment set-up and injection rates were priced and compared.

The capital costs assumed an av ailability of 100% until these costs were levelized where a capacity factor of 75% was used. The fixed and variable operating and maintenance costs used a capacity factor of 75% throughout bo th the first year and levelized estimations with an exception of power which used an 85% capacity factor.



### Capital Costs The costs of equipment and installation for the trona injection system and balance-of-plant systems are shown in Table 16. This table compares the cost for one-silo a nd three-silo systems. Capital costs for a permanent trona injection sy stem include the storage silo(s), blowers, conveyor piping, dehumidifiers, and modifications to the ash handling system. Cost estimates for the trona storage and inje ction equipment and installati on costs were provided by Bulk Conveyor Specialist, Inc. A descripti on of capital equipment is shown below.

• Storage Silo : Skirted, carbon steel shell with cone. Stor age capacity of 75 tons. Includes bin vent collector, bin discharger, discharge valve, bin indicat ors, weigh hopper, rotary valves, control panel, blowers, dehumidifiers. Bin Vent Collector: Shaker type, 280 sq. ft. cloth, air-to-cloth ratio of 3:1.

• Bin Discharger: 8 in. diameter, 1 Hp motor.

• Discharge Valve: pneumatic knife gate.

• Bin Indicators: (3) paddle type.

• Weigh Hopper: 2000 lb capacity with load cells , 1.5 Hp rotary valve feeders, and one level indicator.

• Control Panel: Allen Bradley, PLC Logic.

• Blowers : 350 CFM, 8-10 psi with in-and-out silencers.

• Conveyor Piping : 3” schedule 80, estimated length of 300’.

• Lances : 2” schedule 80 pipe, 304 stainless steel, 5’2” in length from flange to tip with 45 degree beveled tip.

• Housing for Redundant Blowers and Dehumidifiers : Skirted silo does not have sufficient space available for redundant blowers and dehumidi fiers, a small building would be required.

• Mechanical Exhauster Package : Exhauster motor size increased from 10 Hp to 20-25 Hp, capable of pulling 15 inHg (14 inHg at full load).

• Larger Capacity Filter/Separator : Two larger, continuous operating filter/separators. Modifications to bin roof by extending 14’ and bin structure by modifying support steel frame across bin roof to accept higher loads.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

33 Table 16. Summary of Equipment, Bala nce-of-Plant, and Engineering Costs Trona Injection System and Balance-of-P lant Equipment and Installation Costs Presque Isle Power Plant Units 7, 8, and 9 Budget Item Description Cost 1 SILO 3 SILOS Trona Storage/Injection System Silo $ 595,000 $ 1,785,000

Equipment Included 75 ton Capacity Storage Silo 1 Hopper Below Silo
1 Blower 1 Dehumidifier Package Conveyor Piping (300 ft) Lances (*Injection lances from test can be used in permanent

system; additional lances are optional at $5,000 per lance) $ 5,000* $ 5,000* Redundancy (equipment added for 3 injection lines per 1 silo) $ 98,500 $ - Splitter Valve 2 Hoppers 2 Rotary Valves 2 Blowers 2 Dehumidifier Packages Housing for Blowers and dehumidifiers Installation of Trona Storage/Injection Equipment $ 580,000 $ 580,000 Includes civil, electrical, m echanical and piping TOTAL PROCESS EQUIPMENT $ 1,273,500 $ 2,365,000

Increase In Ash Handling Capabilities 2 Mechanical Exhauster Packages $ 15,000 $ 15,000 Exhauster motor size increase (10 Hp to 20-25 Hp) Larger Capacity Filter/Separator $ 200,000 $ 200,000 Design and Supply TOTAL ASH HANDLING EQUIPMENT UPGRADES $ 215,000 $ 215,000 TOTAL EQUIPMENT COSTS (TEC) $ 1,488,500 $ 2,580,000
General Facilities (10% of TEC) $148,850 $258,000 Engineering and Home office Fees (12.5% of TEC) $186,062 $322,500 Project Contingency (25% of Process Equip. + 20% of Ash Handling Equip.) $361,375 $634,250 Process Contingency (7.5% of Process Equip. + 5% of Ash Handling Equip.) $106,262 $188,125 TOTAL PLANT COST (TPC) $2,291,050 $3,982,875 Preproduction Costs (=(1/12)*(Fixed O&M + Var O&M)+.02*TPC) $397,921 $431,757 TOTAL CAPITAL REQUIREMENT (TCR) $2,688,971 $4,414,632Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

34 

### Operating and Maintenance Costs The operating and maintenance (O&M) costs associated with trona injection for SO 2 control include fixed and variable costs. Fixed O&M costs include labor, main tenance materials, and administrative and support labor. The variable O&M costs vary depending on unit and other capacity factors and include sorben t, power, and waste disposal.

Fixed O&M Costs
The fixed O&M costs include estimates of labor costs for ash handling and costs for operating and maintenance of the silo and injection equipment. It also includes estimates for maintenance materials and for administrative and support labo r. The maintenance labor, materials and support labor are estimated using known costs for the TOXECON system installed and operating at Presque Isle.

Table 17 shows the operating labor cost parame ters assumed for this cost analysis.

Table 17. Fixed O & M Costs – Ash Handling Labor Cost Parameters Ash Handling Operating Labor Cost Parameters Operating Labor Cost Parameter

Ash Handling rate $/hr (truck+ driver) $70 ton/load (tons) 20 time/load (hrs) 5 Normal Capacity Factor 0.75

Table 18 indicates how the Ash Handling Labor cost estimates were determ ined using the labor parameters indicated in Table 17 along with the number of load s of trona/ash/PAC required for the three SO 2 removal rates of 45%, 64% and 70%. The labor costs increase as SO 2 removal rates increase due to the need for more frequent ash unloading and disposal. The 2007 rate for an ash truck and driver is about $70/hr with ea ch truck-load capable of hauling 40,000 lbs or 20 tons. It takes roughly 5 hours to unload th e ash and dispose of it in the landfill.

The number of loads of trona/ash/P AC to be disposed of assumes 100% material injected will be captured and disposed of and also incorporates a capacity factor of 75%. The equation below was used to determine the number of loads per year:

# Loads/Year = (((WPR trona + WPR PAC )*NCF)–((WPR PAC,no trona inj. )*NCF)) / (Tons per load)

WPR: Waste Producti on Rate (tons/hour) NCF: Normal Capacity FactorTopical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

35 Table 18. Fixed O & M Costs – Ash Handling Labor Costs for Three SO 2 Removal Rates Fixed O&M Cost: Ash Handling Operating Labor SO 2 Removal Rate 45% 64% 70% # of Loads Per Year

Trona + DARCO ® Hg + Ash 379 760 1022 Trona + DARCO ® Hg-LH + Ash 361 734 987 Man-hours Per Year

Trona + DARCO ® Hg + Ash 1896 3798 5112 Trona + DARCO ® Hg-LH + Ash 1807 3669 4936 Labor Costs for Ash Handling ($/yr) Trona + DARCO ® Hg + Ash $132,739 $265,880 $357,860 Trona + DARCO ® Hg-LH + Ash $126,473 $256,797 $345,500

The operating labor costs for the silo and inje ction equipment are constant for different SO 2 removal rates as well as constant with either one-silo or three-silo systems. The operating, maintenance and project overhead costs are estima ted from the annual costs associated with the TOXECON system currently at Presque Isle. Th e maintenance materials are estimated in the same manner. The first year labor costs on proj ects such as this are usually higher than the following years due to the first year start-up issues and optimization of long-term operation. Table 19 shows the fixed costs of equipm ent operating, maintenance and support labor.

Table 19. Fixed Operating & Maintenance Co sts for Equipment Operating, Maintenance and Support Labor Fixed O&M Cost: Equipment Operati ng, Maintenance, and Support Labor 1st Year Operating Labor Costs 1 SILO 3 SILOS

Operating & Maintenance Labor Co sts, in $/yr* $360,000 $360,000

* Includes operating labor, maintenanc e labor, project overhead costs Maintenance Materials, in $/yr $108,000 $108,000

TOTAL FIRST YEAR OPERATING, MAINTENANCE, AND SUPPORT COSTS $468,000 $468,000

.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

36 Table 20. Total First Year Fixed Operating & Maintenance Costs
Total First Year Fixed O&M Cost 1 or 3 Silos SO 2 Removal Rate O&M Labor & Material Costs* 45% 64% 70% Labor Costs for Ash Handling Trona + DARCO ® Hg + Ash $132,740 $265,880 $357,860 Trona + DARCO ® Hg-LH + Ash $126,470 $256,800 $345,500

Labor Costs for Silo and Injection

Equipment

Total First Year Operating,

Maintenance, & Support Costs $468,000 $468,000 $468,000
T OTAL O&M COSTS, 1 or 3 SILOS

(Trona + DARCO ® Hg + Ash) $600,740 $733,880 $825,860
T OTAL O&M COSTS, 1 or 3 SILOS

(Trona + DARCO ® Hg-LH + Ash) $594,470 $724,800 $813,500

Variable O&M Costs
The variable O&M costs include estimates for sorb ent costs, landfill costs and power costs. The sorbent costs include trona as well as the increas ed PAC needed to keep the mercury removal at 90%. Power costs were estimated from the equi pment’s power requirements and the current cost of power production.

Power Costs The electrical requirements for the trona injection system incl ude power for blowers, rotary valve motors, bin discharger, and dehumidifiers. Each injection system requires power for one blower, one dehumidifier, and one ro tary valve. There is one bin di scharger per silo, therefore, if there is one large silo power for one discharg er is needed, but with 3 silos power for 3 dischargers is needed. The long-term running power required is roughl y half of the power required for start-up. Table 21 shows the amperage needed for the different components and the conversion to kilowatts. Table 22 shows the es timated costs required for long-term running of the injection system using an assumed cost to produce power of $0.03/kWh. The power cost estimations use a Power Capacity Factor of 85%.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

37 Table 21. Power Requirements to Run Trona Injection System Power Requirements, 1 Injection System (Amps) Item Motor Description Amps Required Blowers: 30 Hp, 480 Vac, 3 phase 40 amps at full load Rotary Valve: 1 Hp each (2) 1.6 amps each (2) Bin Discharger: 1.5 Hp 3.0 amps TOTAL AMPS AT FULL LOAD 46.2 amps TOTAL AMPS WHILE RUNNING (~1/2 Full Load) 20 amps

Dehumidifiers: 40 amps

TOTAL (amps) 60 amps Power Requirements, 1 Injection System (kW) TOTAL in kW, 3 phase (kW=(1.73*Volt s*Current*Power Factor)/1000) 42.35 Power Capacity Factor 0.85 Volts 480 Power Requirements, 3 Injection Systems (kW) TOTAL in kW, 3 phase 127.05

Table 22. Variable Operating & Maintenance Costs for Power
Variable O&M Costs: Power 1 Injection System 3 Injection Systems Power Usage, in kW 42.35 127.05 Unit Power Cost, in $/kWh $0.03 $0.03 Power Cost, in $/yr $11,125 $33,375

Sorbent Costs Sorbent costs vary depending on the SO 2 removal percentage desired and on the delivery method. Cost for both trona and PAC increase as SO 2 removal percentages increase. The cost for trona to be railed directly to the plant is $140/ton assuming th e costs to install a rail spur is picked up under another project. If a rail spur is not installed to the plant the trona can be railed to Ishpeming then loaded into a truck from ther e and delivered to the plant by truck. Using a combination of rail and tr uck would cost $155/ton.

The amount of PAC needed to maintain 90% me rcury control increases as trona injection increases due to trona interfering with the PAC’s ability to capture mercur y. Table 23 shows the sorbent costs for trona being delivered directly to the plant by rail and Table 24 shows the sorbent costs for trona being delivered by a combinat ion of rail and truck. Both tables have unit costs for trona, DARCO ® Hg, and DARCO ® Hg-LH and display the injection rates required for different SO 2 removals. The sorbent cost estimati ons use a capacity factor of 75%Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

38 Table 23. Variable Operating & Maintenance Costs for Sorbent Delivered by Rail to the Plant Variable O&M Costs: Sorbent Delivered By Rail to Plant Sorbent Unit Cost, FOB PIPP , in $/ton Rail* Trona $140 DARCO ® Hg $1,100 DARCO ® Hg-LH $2,100
*Trona rail spur assumed to be installed under separate project Injection Rates (ton/hr)

Sorbent SO2 Removal of 45% SO2 Removal of 64% SO2 Removal of 70% Trona 1.1 2.2 2.95 DARCO ® Hg 0.142 0.20 0.25 DARCO ® Hg-LH 0.085 0.1185 0.14 Sorbent Costs, in $/yr**

Trona + DARCO ® Hg $1,405,651 $2,836,597 $3,887,797 Trona + DARCO ® Hg-LH $1,460,182 $2,934,162 $3,920,647

**minus PAC that would already be injected

Table 24. Variable Operating & Mainte nance Costs for Sorbent Delivered by a Combination of Rail and Truck to the Plant Variable O&M Costs: Sorbent Delivered By Rail and Trucked To Plant Sorbent Unit Cost, FOB PIPP , in $/ton Rail + Truck* Trona $155 DARCO ® Hg $1,100 DARCO ® Hg-LH $2,100 *Trona railed to Ishpeming and trucked to plant Injection Rates (ton/hr)

Sorbent SO2 Removal of 45% SO2 Removal of 64% SO2 Removal of 70% Trona 1.1 2.2 2.95 DARCO ® Hg 0.142 0.20 0.25 DARCO ® Hg-LH 0.085 0.1185 0.14 Sorbent Costs, in $/yr**

Trona + DARCO ® Hg $1,514,056 $3,053,407 $4,178,520 Trona + DARCO ® Hg-LH $1,568,587 $3,150,972 $4,211,370

**minus PAC that would already be injected

Waste Disposal Costs The variable O&M costs for waste disposal are the costs required to la ndfill the spent sorbent captured in the baghouse. The 2007 unit cost to landfill material was $44.40. Table 25 shows the waste produced for the different SO 2 removal rates and the costs required to landfill the waste. The costs do not include the ash and PAC waste that is di sposed of while running at full load with no trona injected. The waste disposal cost estimations use a capacity factor of 75%.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

39 Table 25. Variable Operating & Maintenanc e Costs for Disposing the Waste to the Landfill Variable O&M Costs: Waste Disposal Landfill Cost, in $/ton $ 44.40
Waste Production Rates (ton/hr) Waste Product SO2 Removal of 45% SO2 Removal of 64% SO2 Removal of 70% Trona 1.1 2.2 2.95 Hg 0.142 0.20 0.25 Hg-LH 0.085 0.1185 0.14 Ash (110 lb/hr) 0.055 0.055 0.055 Waste Disposal Costs, in $/yr** Trona + DARCO ® Hg $336,777 $674,575 $907,941 Trona + DARCO ® Hg-LH $330,560 $661,010 $886,063

**minus PAC/Ash waste that would already be disposed of

Table 26 shows the total variable O&M costs at different SO 2 removal rates and at different delivery methods. The total O&M costs include co sts for power, sorbent usage, and disposal
costs.

Table 26. Total Variable Operating & Maintenance Costs
Total Variable O&M Costs Removal Rates

Total Variable O&M Costs, in $/yr SO2 Removal of 45% SO2 Removal of 64% SO2 Removal of 70% Trona Delivered by Rail to Plant Trona + DARCO ® Hg $1,775,803 $3,544,547 $4,829,114 Trona + DARCO ® Hg-LH $1,823,917 $3,628,547 $4,840,085 Trona Delivered by Rail/Truck Trona + DARCO ® Hg $1,884,208 $3,761,357 $5,119,836 Trona + DARCO ® Hg-LH $1,932,322 $3,845,357 $5,130,808



### Levelized Costs Levelized costs were computed to represent a co nstant cost value for the operating and capital costs over the lifetime of the equi pment and project. In other words, the levelized costs take the present value of the net costs and spread them evenly over a period of time. This makes it possible to compare costs looking into the futu re. For this assessment levelized costs are presented in units of mills/kWh, where a mill is 1/1000 of a dollar.

The calculations to determine levelized costs assumed a discount rate of 7.5% and a 20-year levelization factor was used. Th e capital costs are converted usi ng a fixed charge rate of 15.0% and the O&M costs are converted using levelization factors of 1.29 for all costs including power and consumables.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

40 Levelized Capital Costs The capital costs are converted to levelized capital costs using a fixed charge rate of 15.0%. The levelized capital costs for $/year are calculated by multiplying the capital costs by the fixed charge rate of 15.0%. The levelized capital costs in $/kW are cal culated by dividing the $/year amount by the nominal kilowatts produced by the pl ant, 270000kW for Presque Isle Power Plant. The levelized costs represented by mills/kWh are calculated using the following formula and a capacity factor (NCF) of 75%.

LCC (mills/kWh) = ((1000) * (CC) * (LFCR)) / ((NCF) * (8760 hr/yr))

LCC: Levelized Capital Costs CC: Capital Costs ($/kW) LFCR: Levelized Fixed Charge Rate NCF: Normalized Capacity Factor

Table 27 shows the levelized capital costs and co mpares costs for a one-silo system versus a three-silo system. The total capital require ment for three silos is less than double the requirement for one silo.

Table 27. Levelized Capital Costs Levelized Capital Costs (20 yr, Current $ Basis) Levelized Fixed Charge Rate 15%

1 SILO 3 SILOS TOTAL LEVELIZED EQUIPMENT COST (Installed) Levelized $/yr (TEC * LFCR) $223,275 $387,000 Levelized $/kW (TEC * LFCR / 270000 kW) $0.83 $1.43 mills/kWh (1000* TEC*LFCR)/(270000kW*(8760 hrs/yr)*NCF)) 0.13 0.22

TOTAL LEVELIZED PLANT COST Levelized $/yr (TPC * LFCR) $343,657 $597,431 Levelized $/kW (TPC * LFCR / 270000 kW) $1.27 $2.21 mills/kWh (1000* TPC*LFCR)/(270000kW*(8760 hrs/yr)*NCF)) 0.19 0.34

TOTAL LEVELIZED CAPITAL REQUIREMENT Levelized $/yr (TCR * LFCR) $403,345 $662,195 Levelized $/kW (TCR * LFCR / 270000 kW) $1.49 $2.45 mills/kWh (1000* TCR*LFCR)/(270000kW*(8760 hrs/yr)*NCF)) 0.23 0.37

Levelized Fixed O&M Costs Tables 28 and 29 show the fixed operating and maintenance levelized costs for ash handling labor and equipment operating, maintenance, and s upport labor. These tables are summarized in Table 30. The calculations for the levelized fi xed O&M costs are done in the same manner as the levelized capital costs but use a levelization factor of 1.29 in accordance with the EPRI Economic Analysis rather than the 15% fixed charge rate.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

41 Table 28. Levelized Fixed Operating & Maintenance Costs for Ash Handling Labor Levelized Fixed O&M Cost: Ash Handling Operating Labor Operating Labor Levelization Factors

Ash Handling Capacity Factor 75% O&M Levelization Factor 1.29

Removal Rates SO2 Removal of 45% SO2 Removal of 64% SO2 Removal of 70% Levelized Labor Costs for Ash Handling Trona + DARCO ® Hg + Ash $/yr $171,233 $342,985 $461,639 $/kW $0.63 $1.27 $1.71 mills/kWh 0.10 0.19 0.26 Trona + DARCO ® Hg-LH + Ash $/yr $163,150 $331,268 $445,695 $/kW $0.60 $1.23 $1.65 mills/kWh 0.09 0.19 0.25

Table 29. Levelized Fixed Operating & Ma intenance Costs for Equipment Operating, Maintenance, and Support Labor Levelized Fixed O&M COST: Equipment Operating, Maintenance, and Support Labor Operating Labor Levelization Factors Equipment Operating, Maintenance, and Support Labor

Capacity Factor 75% O&M Levelization Factor 1.29 1 or 3 Silo(s) Levelized Operating & Maintenance Labor Costs * $/yr $464,400 $/kW $1.72 mills/kWh 0.26 *Includes operating labor, mainte nance labor, project overhead costs

Levelized Maintenance Materials $/yr $139,320 $/kW $0.52 mills/kWh 0.08

TOTAL LEVELIZED OPERATING, MAINTENANCE, AND SUPPORT COSTS $/yr $603,720 $/kW $2.24 mills/kWh 0.34Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

42 Table 30. Levelized Total Operating & Maintenance Costs Levelized Total Fixed O&M Cost Operating Labor Levelization Factors Capacity Factor 75% O&M Levelization Factor 1.29

Removal Rates SO2 Removal of 45% SO2 Removal of 64% SO2 Removal of 70% Levelized Total Fixed O&M Costs

Trona + DARCO ® Hg + Ash $/yr $774,953 $946,705 $1,065,360 $/kW $2.87 $3.51 $3.95 mills/kWh 0.44 0.53 0.60 Trona + DARCO ® Hg-LH + Ash $/yr $766,870 $934,990 $1,049,415 $/kW $2.84 $3.46 $3.89 mills/kWh 0.43 0.53 0.59

Levelized Fixed O&M Costs Tables 31 through 34 show the variable operatin g and maintenance levelized costs for power, sorbents, and waste disposal. Th ese tables are summarized in Ta ble 35. The calculations for the levelized variable O&M costs are done in the same manner as the levelized fixed O&M costs and use a levelization factor of 1.29 in accordance with the EPRI Economic Analysis.

Levelized Power Costs Table 31 shows the levelized power costs. A capacity factor of 75% is assumed and a levelization factor of 1.29 is used for power in accordance with the EPRI Economic Analysis.

Table 31. Levelized Variable Operat ing & Maintenance Costs for Power
Levelized Variable O&M Costs: Power Capacity Factor 0.75 Levelization Factor 1.29

1 Injection System 3 Injection Systems Power Usage, in kW 42.35 127.05 Levelized Power Cost $/yr $14,351 $43,054 $/kW 0.05 0.16 mills/kWh 0.008 0.024

Levelized Sorbent Costs
Table 32 shows the levelized costs for sorbent deliv ered to the plant by rail. Table 33 shows the levelized costs for sorbent delivered to the plant by rail/truck. The levelized costs for trona and DARCO ® Hg are compared to the leve lized costs of trona and DARCO ® Hg-LH at threeTopical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

43 different SO 2 removal rates. A capacity factor of 75% is assumed and a le velization factor of 1.29 was used in accordance with the EPRI Economic Analysis.

Table 32. Levelized Variable Operating & Ma intenance Costs for Sorbent Delivered by Rail to the Plant
Levelized Variable O&M Costs: Sorb ent Delivered By Rail to Plant Capacity Factor 75% Levelization Factor 1.29 Removal Rates

Levelized Sorbent Costs SO2 Removal of 45% SO2 Removal of 64% SO2 Removal of 70%

Trona + DARCO ® Hg* $/yr $1,813,290 $3,659,211 $5,015,259 $/kW $6.72 $13.55 $18.58 mills/kWh 1.02 2.06 2.83

Trona + DARCO ® Hg-LH* $/yr $1,883,635 $3,785,069 $5,057,635 $/kW $6.98 $14.02 $18.73 mills/kWh 1.06 2.13 2.85
*minus PAC that would already be injected

Table 33. Levelized Variable Operating & Ma intenance Costs for Sorbent Delivered by a Combination of Rail and Truck to the Plant
Levelized Variable O&M Costs: Sorbent De livered By Rail and Trucked to Plant Capacity Factor 75% Levelization Factor 1.29 Removal Rates

Levelized Sorbent Costs SO2 Removal of 45% SO2 Removal of 64% SO2 Removal of 70%

Trona + DARCO ® Hg* $/yr $1,953,133 $3,938,896 $5,390,291 $/kW $7.23 $14.59 $19.96 mills/kWh 1.10 2.22 3.04

Trona + DARCO ® Hg-LH* $/yr $2,023,478 $4,064,754 $5,432,667 $/kW $7.49 $15.05 $20.12 mills/kWh 1.14 2.29 3.06
*minus PAC that would already be injected
Levelized Waste Disposal Costs
Table 34 shows the levelized wa ste disposal costs. The le velized costs for landfilling a combination of trona, DARCO ® Hg and ash are compared to le velized costs for landfilling trona, DARCO ® Hg-LH and ash at three different SO 2 removal rates. A capacity factor of 75% was assumed and a levelization factor of 1.29 was used in accordance with the EPRI Economic Analysis.Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

44 Table 34. Levelized Variable Operating & Maintenance Costs for Waste Disposal Levelized Variable O&M Costs: Waste Disposal Capacity Factor 75% Levelization Factor 1.29 Removal Rates

Levelized Waste Disposal Costs SO2 Removal of 45% SO2 Removal of 64% SO2 Removal of 70%

Trona + DARCO ® Hg* $/yr $434,422 $870,200 $1,171,244 $/kW $1.61 $3.22 $4.34 mills/kWh 0.24 0.49 0.66 Trona + DARCO ® Hg-LH* $/yr $426,164 $852,703 $1,143,021 $/kW $1.58 $3.16 $4.23 mills/kWh 0.24 0.48 0.64
*minus PAC that would already be injected

Total Levelized Variable O&M Costs Table 35 shows the total levelized variable operati ng and maintenance costs. The levelized costs for power, sorbent, and waste disposal are adde d up and can be compared as one silo versus three silos at three different SO 2 removal rates.

Table 35. Levelized Total Variable Operating & Maintenance Costs Levelized Total Variable O&M Costs Removal Rates

Levelized Total Variable O&M Cost SO2 Removal of 45% SO2 Removal of 64% SO2 Removal of 70% Trona Delivered by Rail to Plant

Trona + DARCO ® Hg $/yr $2,290,786 $4,572,466 $6,229,557 $/kW $8.48 $16.94 $23.07 mills/kWh 1.29 2.58 3.51 Trona + DARCO ® Hg-LH $/yr $2,352,853 $4,680,826 $6,243,710 $/kW $8.71 $17.34 $23.12 mills/kWh 1.33 2.64 3.52 Trona Delivered by Rail/Truck

Trona + DARCO ® Hg $/yr $2,430,629 $4,852,150 $6,604,588 $/kW $9.00 $17.97 $24.46 mills/kWh 1.37 2.74 3.72 Trona + DARCO ® Hg-LH $/yr $2,492,695 $4,960,510 $6,618,742 $/kW $9.23 $18.37 $24.51 mills/kWh 1.41 2.80 3.72Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

45 Total Levelized Costs Table 36 shows the total levelized costs, which in cludes the total variable O&M costs, total fixed O&M costs and total capital costs at three removal rates.

Table 36. Levelized Costs (Capital, Fixe d, and Variable Levelized Costs) Levelized Total Costs Removal Rates Total Levelized Cost (Capital, Fixed, and Variable Costs) SO2 Removal of 45% SO2 Removal of 64% SO2 Removal of 70% 1 SILO Trona Delivered by Rail to Plant

Trona + DARCO ® Hg $/yr $3,469,084.86 $5,922, 516.40 $7,698,261.25 $/kW $12.85 $21.94 $28.51 mills/kWh 1.96 3.34 4.34 Trona + DARCO ® Hg -LH $/yr $3,523,067.86 $6,019, 159.39 $7,696,470.85 $/kW $13.05 $22.29 $28.51 mills/kWh 1.99 3.39 4.34 Trona Delivered by Rail/Truck

Trona + DARCO ® Hg $/yr $3,608,927.31 $6,202, 201.30 $8,073,293.28 $/kW $13.37 $22.97 $29.90 mills/kWh 2.03 3.50 4.55 Trona + DARCO ® Hg -LH $/yr $3,662,910.31 $6,298, 844.29 $8,071,502.87 $/kW $13.57 $23.33 $29.89 mills/kWh 2.06 3.55 4.55

3 SILOS Trona Delivered by Rail to Plant

Trona + DARCO ® Hg $/yr $3,727,934.08 $6,181, 365.62 $7,957,110.48 $/kW $13.81 $22.89 $29.47 mills/kWh 2.10 3.48 4.49 Trona + DARCO ® Hg -LH $/yr $3,781,917.08 $6,278, 008.62 $7,955,320.07 $/kW $14.01 $23.25 $29.46 mills/kWh 2.13 3.54 4.48 Trona Delivered by Rail/Truck

Trona + DARCO ® Hg $/yr $3,867,776.53 $6,461, 050.52 $8,332,142.50 $/kW $14.33 $23.93 $30.86 mills/kWh 2.18 3.64 4.70 Trona + DARCO ® Hg -LH $/yr $3,921,759.53 $6,557, 693.52 $8,330,352.10 $/kW $14.53 $24.29 $30.85 mills/kWh 2.21 3.70 4.70Topical Report: Trona-Based SO 2 /NO x Removal at Presque Isle

46 

### Removal Cost per Ton of SO 2 

### Removed Table 37 shows the cost per ton of SO 2 removed using trona at full scale. These values are levelized over 20 years. The amount of SO 2 removed is based on the baseline emission rate of 5,200 tons per year for all three units combined. The cost per ton of SO 2 removed is calculated by dividing the levelized total costs ($/yr) given in table 36 by the amount removed from the baseline for each removal rate. The cost per ton of SO 2 removed varied from $1,483 to $2,290.

Table 37. Removal Costs per Ton SO 2 Removed Levelized Total Cost per Ton of SO 2 Removed ($/ton) No. of Silos, Delivery Method, and Sorbent SO 2 Removal Rate

* 45% 64% 70%

1 SILO Trona Delivered by Rail to Plant

Trona + DARCO ® Hg $1,483 $1,780 $2,116 Trona + DARCO ® Hg-LH $1,506 $1,809 $2,115

Trona Delivered by Rail/Truck

Trona + DARCO ® Hg $1,543 $1,864 $2,219 Trona + DARCO ® Hg-LH $1,566 $1,893 $2,218

3 SILOS Trona Delivered by Rail to Plant

Trona + DARCO ® Hg $1,594 $1,858 $2,187 Trona + DARCO ® Hg-LH $1,617 $1,887 $2,186

Trona Delivered by Rail/Truck

Trona + DARCO ® Hg $1,654 $1,942 $2,290 Trona + DARCO ® Hg-LH $1,677 $1,971 $2,290