P 0. Box 52025 Mail Station: PAB352 

Phoenix, AZ 85072-2025 Direct Phone: (602) 236-2968 

(602) 236-5900	 Fax.' (602) 236-3407 

www.srpnet.com E-mail: Kevin.wanttaja@srpnet.com 

FEDEX OVERNIGHT 

July 29, 2008	 RECEIVED 

Ms. Deborah Jordan, Air Division Director JUL 3 0 2008 USEP A Region 9 

Mail Code: AIR-l 

Air Division,AIR- .~ 75 Hawthorne Street U.S. EPA, REGION 9 

San Francisco, CA 94105 

Re:	 Best Available Retrofit Technology (BART) Analysis - Cost Information 

Navajo Generating Station 

Dear Ms. Jordan: 

This letter provides an initial response to your information request letter dated July 1, 2008. 

Specifically, this letter responds to the information requests entitled "Cost of Compliance" and 

"Total Capital Costs of NOx Control Options". Salt River Project (SRP) will be submitting an 

updated BART analysis for the Navajo Generating Station (NGS) that will address all issues 

within the July 15t letter; however, we are providing information related to these issues prior to 

our complete submittal as your staff has requested. 

Cost of Compliance 

EPA requested that SRP provide additional documentation, explanation, and justification for the 

cost estimates provided for the three nitrogen oxide (NOx) control options. For the 10w-NOx 

burner (LNB)/separated overfire air (SOFA) systems, the cost for each system was assumed to 

be $10 million in the analysis. This value was a high-level budgetary estimate based on initial 

discussions with major LNB/SOFA equipment suppliers. Now that more research into the costs 

associated with LNB/SOFA systems has been accomplished, SRP is finding that the actual total 

capital cost per unit is closer to $14 million. 

For the selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) 

systems, the cost estimates were based on a cost study performed by Sargent & Lundy. A copy 

of this analysis is attached to this letter. As you will see when comparing this information to the 

BART analysis previously submitted, the costs do not match for all scenarios. The Sargent & 

Lundy report is correct, and the revised BART analysis will be updated to reflect the correct 

values. The correct total capital costs and annual operation and maintenance costs for each 

scenario are summarized in the following table. 

sc136030708 
Ms. Deborah Jordan, Air Division Director 

July 29, 2008 

Page 2 of2 

Control 

Option Control Technology Total Capital Cost* 

($) 

Annual Operation & 

Maintenance Cost 

($/yr) 

II Alt. 1 LNB/SOFA (Units 1-3) 30,000,000 0 

2 LNB/SOFA & SNCR (Units 1-3) 60,000,000 15,978,000 

3 

LNB/SOFA (Unit 2) 

LNB/SOFA & SCR (Units 1 & 3) 406,000,000 8,316,000 

4 LNB/SOFA & SCR (Units 1-3) 660,000,000 12,474,000 . . .. * As noted In this letter, actual costs for the LNB/SOFA systems are anticipated to be closer to $14 million per unit. 

This would increase all total capital cost figures provided in this analysis by an additional $12 million. 

Total Capital Costs of NO x Control Options 

EPA requested that SRP provide justification for the NOx control option estimates, and explain 

why the connections would not be scheduled to coincide with scheduled unit outages. Cost 

estimate information is provided in the response to the issue above. With regards to why the 

connections would not be scheduled to coincide with scheduled unit outages, this information 

also is included in the Sargent & Lundy cost study (i.e., the cost basis and the time required). As 

the study states, the outages are assumed to occur during scheduled major outages. However, 

normal major outages are not long enough to perform all of the work related to installation of 

SCR on the units, so the outage cost included in the total capital cost estimate is the incremental 

cost of extending those outages. 

If you have any questions regarding this information or the previous BART submittals, please 

contact Barbara Sprungl at (602) 236-5374 or me at (602) 236-2968. 

Sincerely, 

~~j[~f'
 Kevin Wanttaji, Manager 

Environmental Services 

cc w/attachments: Colleen McKaughan, EPA Region 9 

Steven Frey, EPA Region 9 

Anita Lee, EPA Region 9 

Scott Bohning, EPA Region 9 

Stephen Etsitty, Navajo Nation EPA 

Robert Talbot, NOS 

LOC 6-2-7.1 

IXI36030708 
o.liveri"9 more than power.. 

SALT RIVER PROJECT 

NAVAJO GENERATING STATION 

SCR & SNCR COST STUDY 

FINAL REPORT 

Prepared By: 

Project No. 11234-028 

July 25, 2008 

Rev. 3 
ail~'~'"

...... 

Der...,.rhlg mare than poww.' Project No. 11234-028 

July 25, 2008 

Navajo Generating Station Rev. 3 

SCR &SNCR Cost Study 

Navajo Generating Station 

SCR & SNCR Cost Study 

Issue Summary 

Revision Date Purpose Prepared By Reviewed By Approved By Pages 

Number Affected 

A 09/14/07 Client Comment R. Gaikwad A. Baker E. Shameem All 

B 09/21/07 Client Comment R. Gaikwad A. Baker E. Shameem 1,8-12 

0 10/04/07 Final Issue R. Gaikwad A. Baker E. Shameem All 

1 10/19/07 Updated O&M 

Costs R. Gaikwad A. Baker E. Shameem 17 

2 11/16/07 Updated O&M 

Costs R. Gaikwad A. Baker E. Shameem 17 

3 7/25/2008 Final rfibd -­

f­ /.vl .. ~/f¥'T .,.....-­

......... 

All 

. Gaikwad A. Baker E. Shameem 

15-1 

5argo " Lundy'" 
1 

.,;~,~..

.,.....
 

Delivering more tl_ power,' 

Navajo Generating Station
 

SCR & SNCR Cost Study
 

TABLE OF CONTENTS 

SECTION TITLE 

ISSUE SUMMARY 

TABLE OF CONTENTS 

1 PURPOSE 

2 INTRODUCTION 

3 INPUT DATA 

4 METHODOLOGY 

5 DESCRIPTION OF CONTROL TECHNOLOGIES 

6 CONSTRUCTABILITY 

7 ESTIMATED CAPITAL COSTS 

8 ESTIMATED O&M COSTS 

ATTACHMENTS 

LAYOUTS FOR STUDY OPTIONS 

Project No. 11234-028 

July 25, 2008 

Rev. 3 

PAGE NO. 

IS-1 

1
 

2
 

2
 

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4 

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 Project No. 11234-028 Delivering mor. than power.' July 25,2008 

Navajo Generating Station Rev. 3 

SCR & SNCR Cost Study 

1. Purpose 

The main objective of this study is to support the Best Available Retrofit Technology (BART) 

analysis for the Navajo Generation Station (NGS) by performing a hlgh level review of 

feasibility and development of a capital cost estimate for installing Selective Catalytic 

Reduction (SCR) or Selective Non-Catalytic Reduction (SNCR) on all three units. 

2. Introduction 

The NGS is located near Page, AZ. and consists of three nominally 750 MW units that were 

built in the late 1970s. The boilers burn a low sulfur fuel from a nearby mine. The units 

were originally equipped with hot-side electrostatic precipitators (HESP) and were retrofitted 

with wet flue gas desulfurization (WFGD) systems in the 1990s. The HESPs are stacked 

units. New wet chimneys were installed as part of the WFGD retrofit project and the existing 

chimneys were partially demolished to a height of 195'. 

Currently, the NOx levels from the NGS units are around 0.30-0.40 Ib/mmBtu. The station 

intends to retrofit the boilers with Low NOx Burners and separated overfire air modifications 

(LNB/SOFA) which are expected to reduce NOx levels to approximately 0.24 Ib/mmBtu. 

The intent of this study is to develop high level cost estimates for the addition of SNCR to 

achieve a NOx level of 0.20 Ib/mmBtu or SCR technology to achieve NOx level of 0.08 

Ib/mmBtu. 

Salt River Project (SRP), part owner and operator of NGS, contracted Sargent & Lundy LLC 

(S&L) to investigate the retrofit difficulty associated with implementing these control 

technologies and develop the corresponding high level costs. It should be noted that the 

objective of this study is not to develop conceptual designs for retrofitting these new control 

technologies. but to come up with high level arrangements. 

To achieve the above noted objective, S&L engineers visited the NGS on August 28, 2007 

and met with the plant staff to discuss the study as well as to obtain relevant data. The S&L 

team also performed walkdowns of the units to ascertain the retrofit difficulty. 

2
 
.,;~,~.... ~~ Project No. 11234-028 Der.".,rll1S more !han I'CW""" July 25, 2008 

Navajo Generating Station	 Rev. 3 

SCR & SNCR Cost Study 

3.	 Input Data 

The following data was provided by SRP and was used as the basis for this cost study: 

•	 The typical fuel analysis is provided below: 

Carbon	 69.90 

Hydrogen	 4.90 

Nitrogen	 1.10 

Sulfur	 0.57 

Oxygen	 12.72 

Ash	 10.80 

Moisture	 12.90 

Heating Value, Btu/lb	 10,601 

Hardgove Index	 46.0 

Ash Fusion temp. F (reducing) 2,260 F 

•	 The units fluctuate down 150-200 MW during the night and can go down to 400 MW. 

•	 Major unit outages are scheduled for 55 days and allow 50 days for implementation of 

the new control technologies. 

•	 Heat Input to Boiler - 7,500 mmBtu/hr 

•	 HESP inlet and outlet temperatures are 700 F and 660 F, respectively 

•	 The air preheater (APH) outlet temperature is 275 F. 

3 
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Project No. 11234-028 Dellveril19 more than power," July 25, 2008 

Navajo Generating Station Rev. 3 

SCR & SNCR Cost Study 

• The temperature at the inlet to the wet scrubber is 275 F. 

4, Methodology 

As discussed above, the following control scenarios were investigated: 

Option 1A: LNB/SOFA + HESP + SCR 

Option 1B: LNB/SOFA + HESP + SNCR 

For the above scenarios, it should be noted that the HESP is already in service and that the 

costs associated with the LNB/SOFA modifications have been estimated by SRP at $10 

million per unit. As such, this study will develop costs for the SCR and SNCR only. 

Based on the information gathered during the site visit and walkdown, S&L prepared rough 

layouts for the options noted above. These layouts were used for comparison purposes with 

some of our recent retrofit projects to estimate high level costs. Retrofit difficulty was 

factored into the cost estimates. It should be noted that the SNCR option was added after 

the site visit. 

5, Description of Control Technologies 

The specific control technologies included in the scope of this study are discussed below: 

Selective Catalytic Reduction (SCR): 

SCR is a technology that has received wide use in the last 8 years. In coal based SCR 

systems, the flue gas is treated with a reducing agent, generally ammonia vapor, via an 

injection grid, and is passed over multiple layers of catalyst allowing a reaction with nitrogen 

oxides to take place, forming nitrogen and water. This reaction is temperature sensitive and 

generally occurs in the 560 F - 800 F range. For this reason, the catalyst layers must be 

4 
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 Project No. 11234-028 DeliWlI'ing more than power.' July 25, 2008 

Navajo Generating Station Rev. 3 

SCR & SNCR Cost Study 

located downstream of the economizer outlet and upstream of the air heater. The ammonia 

that slips through the SCR is limited to approximately 2 ppmvd (@3% O2) , 

The catalysts can have different compositions: based on titanium oxide, zeolite, iron oxide or 

activated carbon. Most catalysts in use in coal-fired plants consist of vanadium pentoxide 

(active catalyst) and titanium dioxide (used to disperse and support the vanadium) mixture. 

However, the final catalyst composition can consist of many active metals and support 

materials to meet specific requirements in each SCR installation. The catalyst has an 

average life of 2 to 3 years depending on the fuel and flue gas constituents. SCRs are 

generally designed with space for a spare layer of catalyst so that a portion of the catalyst 

can be replaced with new catalyst at regular intervals. NOx reductions of approximately 80 ­

90% may be achieved with SCR systems. 

Selective Catalytic Reduction (SCR) at NGS could be applied to treat 100% of the total flue 

gas. All three units at NGS have a hot side ESP. The outlet conditions, with very low 

particulate loading, make it possible to retrofit SCRs at the outlet of the HESP. During the 

waIkdown, based on the preliminary sizing of SCR, it was determined that the SCRs can be 

retrofitted on Units 1 and 3 with an average degree of retrofit difficulty. However, retrofitting 

on Unit 2 would be very difficult. The SCR design is based on the inlet NOx of 0.24 

Ib/mmBtu to achieve outlet emission of approximately 0.08 Ib/mmBtu. 

Selective Non-Catalytic Reduction (SNCR1: 

The SNCR process requires that injection of either ammonia or urea into the flue gas occurs 

within a temperature window of 1600-2100°F to reduce NOx to nitrogen and water. Multiple 

injection levels are used to maintain NOx reduction efficiencies as the boiler load changes. 

At temperatures above 2000°F, ammonia and urea react with oxygen to form additional 

NOx. At low flue gas temperatures below 1700°F, excess ammonia can lead to the formation 

of ammonium salts. Due to minimal use of reagent and low removal efficiency, this 

technology typically is applied to smaller units of an existing fleet such that these smaller 

5 
-':~'~.ia

~~ Project No. 11234-028 Delivering ~. thon powe.... July 25, 2008 

Navajo Generating Station Rev. 3 

SCR & SNCR Cost Study 

units can be bubbled with the larger units to satisfy system-wide NOx emission allowance 

limits. Typically, 10-40% NOx removal efficiencies can be achieved with SNCR technology 

depending on boiler conditions. However, for larger units, the technology can be applied as 

a polishing technology achieving 15-20% NOx removal efficiency. For purposes of this 

study, it has been assumed that 15% efficiency is feasible if installed at Navajo units with a 

5-ppm ammonia slip. If SNCR is selected at this efficiency, boiler mapping should be 

performed to determine the exact removal efficiency with this technology. 

6. Constructability 

Unit 1 and Unit 3 SCR's: 

In general, the construction of the SCR's and their associated support structures would be 

relatively straightforward; however, the modifications at the precipitator outlet required to tiein the SCR's would be difficult. With this ductwork located between the boiler and 

precipitator, access to the area near the air heaters is constrained. The extent of the 

modification work required and the limited access to the immediate work area will most likely 

require an extended outage to complete. 

The proposed layout of the Units 1 and 3 SCRs is shown in Attachment 1. In this 

arrangement, the SCR's are located outboard of the units, with tie-ins to the precipitator 

outlet ductwork. S&L anticipates that new ID booster fans would be added downstream of 

the SCRs. It is expected that the modification/tie-in work would require on the order of 9 

t012 weeks to complete. For purposes of the capital cost estimate, it is assumed that the 

retrofit would occur during a major outage, and extend such outage by 4 weeks. 

6
 
a;:~''-t.'"

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 Project No. 11234-028 DeliverIng more thollpoww.' July 25,2008 

Navajo Generating Station Rev. 3 

SCR & SNCR Cost Study 

Unit 2 SCR: 

S&L looked at various alternatives on Unit 2, but with Unit 2 located between Units 1 and 3 

and with other equipment including the coal conveyor and it's supports located immediately 

adjacent to Unit 2, the construction of an SCR in an economical configuration similar to that 

for Units 1 and 3 is not possible. With limited room for the SCR and with limited access for 

construction cranes and equipment, the installation of an SCR on Unit 2 would be extremely 

difficult. The limited access for construction equipment would limit the size of pre-fabricated 

assemblies that can be set directly in place and would drive up the cost of construction 

considerably. In addition, in order to make room for the SCR's and fans on Unit 2, it is 

expected that the remainder of the old Unit 2 chimney would have to be demolished. 

Note that a high dust SCR might be more feasible on Unit 2, however the construction 

difficulties still persist and no major cost saving can be justified with the possible high dust 

configuration. 

The proposed layout of the Unit 2 SCR is shown in Attachment 1. In this arrangement, the 

SCR's would be located adjacent to the existing old chimney (which would be demolished) 

and above the existing 10 fan outlet ductwork. Tie-ins would be made to the precipitator 

outlet ductwork on each side of the unit. New booster fans would be installed in the area 

vacated by the demolition of the old chimney. Note that rework of the 10fan outlet ductwork 

may be required in order to provide clearance for maintenance work on the new booster 

fans. With the limited access for construction equipment, and the close proximity of the coal 

conveyor, it is expected that the modification/tie-in work would require on the order of 12-15 

weeks to complete, primarily due to extreme care that must be taken to avoid any damage 

to the coal conveyor. For purposes of the capital cost estimate, it is assumed that the retrofit 

would occur during a major outage, and extend such outage by 6 weeks. 

7
 
/8i;~'~" .,....,
 Project No. 11234-028 DerMlring men than power." July 25. 2008 

Navajo Generating Station Rev. 3 

SCR & SNCR Cost Study 

SNCR Installation: 

The SNCR investigation was added to the scope of this study after the S&L site visit. Even 

though our walkdown did not investigate this option, the location/s for ammonia or urea 

injection lances are likely available in the 16000F to 21000F temperature range. The reagent 

tanks could be located on plant premises. The boiler penetration for lances can be 

completed within a 4 week outage, and therefore could be completed without extending an 

outage if the work were completed during a normal major outage. 

7.	 Estimated Capital Costs 

The basis of the capital cost estimates provided herein is as follows: 

	 The costs were developed using the internal S&L database of costs which includes 

recently completed and in-progress projects. Adjustments were made to reflect the 

major differences in quantities such as ductwork and structural steel. More 

importantly, these costs were adjusted to account for constructability issues which, in 

some cases, are significant for NGS. It should, however, be noted that these costs 

were estimated at a high level ($/kW). 

	 The estimated costs included are "total plant costs" and include equipment and 

material, direct field labor (including contractor G&A and profit) and indirect costs 

(engineering, construction management and commissioning) 

	 The cost of replacement power ($45/MWh) was provided by SRP. 

The estimated capital costs associated with the various options are as discussed below: 

8
 
a;;~'~..

...." Project No. 11234-028 Dtfwerlng more tha" pow..... July 25, 2008 

Navajo Generating Station Rev. 3 

SCR & SNCR Cost Study 

Units 1 and 3 SCR: 

Based on an overall degree of difficulty, the capital cost for a low dust SCR system on either 

Unit 1 or 3 is estimated to be approximately $165 million. Lost generation costs based on 

extending major outages for each unit an additional 4 weeks is approximately $23 million 

per unit based on a replacement power cost of $45/MWh. 

Unit 2 SCR: 

With the degree of difficulty of the installation as well as the cost penalties to the Unit 1 

work, the cost for a Unit 2 SCR is estimated to be in the order of $220 million. Lost 

generation costs based on extending a major outage an additional 6 weeks is approximately 

$34 million. Due to the degree of difficulty of the Unit 2 work, it is recommended that further 

feasibility studies are conducted prior to committing to installing an SCR on Unit 2. 

SNCR Installation: 

The capital cost for SNCR installation on each of the units is expected to be approximately 

10 million dollars. Because it is assumed the retrofits could be completed within a current 

major outage, there are assumed to be no lost generation costs. 

Capital Cost Summary: 

Based on the above, the estimated capital costs for the options evaluated are summarized 

in Table 7-1 on the following page. As noted earlier, a more detailed feasibility study and 

detailed cost estimate should be prepared to develop budgetary costs for the control option 

chosen. 

9 
Project No. 11234-028 o.n".rlng man than power.. JUly 25, 2008 

Navajo Generating Station Rev. 3 

SCR & SNCR Cost Study 

Table 7-1 Capital Cost Summary 

Control Technology Costs 

Option Unit (Millions) Outage Costs Total Costs 

lNBlSOFA SCR (Millions) (Millions) 

$10 $165 $23 $198 

1A 2 $10 $220 $34 $264 

3 $10 $165 $23 $198 

$10 $0 $20 

18 2 $10 $0 $20 

3 $10 $0 $20 

8. Estimated O&M Costs 

The estimated O&M costs associated with the SCRs and SNCRs are as follows: 

LNB·SOFAISCR SNCR 

M$/vr M$/vr 

Fixed O&M 0.42 0.10 

Variable O&M, (@90Of. ACF) 

Ammonia ($400/ton). Urea 0.936 1.736 

($400110n) 

Catalyst Replacement 0.342 0 

Aux. Power ($60/MWH) 2.46 0.19 

Lost Ash Sales .. 0 3.4 

Total Variable O&M 4.158 5.326 

.. For purposes of this analysis, it Is assumed that ammonia slip from the SNCR renders fly ash 

unsalable (figure provided by SRP). LNB/SOFA may also impact the salability of the fly ash, but for 

purposes of this analysis, it is assumed that the fly ash can continue to be marketed. 

10
 
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