Document ID: EPA-R08-OAR-2012-0026-0086
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2013-02-11T05:00Z

February 7, 2013
To:  Doug Grano
Fm:  Jim Staudt
Re:  Review of Estimated Compliance Costs for Wyoming Electricity Generating Units (EGUs)   - revision of previous memo
Attachment: Microsoft Excel Workbook WY EGU BART_RP Costs_20121019_revised.xlsx
This is a revision to a memo issued on October 23, 2012.  It is revised based upon corrections to the cost of urea.  On June 4, 2012 (77 FR 33022), EPA proposed the Wyoming Regional Haze Federal implementation plan. Below is Andover Technology Partners' evaluation of the cost of nitrogen oxides NOx emission controls for particular power plants in Wyoming subject to EPA's proposed rulemaking.  These plants and units include:
   * Dave Johnson, units 1-4
   * Laramie River Station, units 1, 2, and 3
   * Naughton units 1, 2 and 3
   * Wyodak

Note that Dave Johnston Units 1-2 are not subject to Best Available Retrofit Technology (BART) requirements, but the cost of compliance for these units has been evaluated here under reasonable progress reguirements.

For each unit, estimates were made for the following technologies, where applicable:
   * Combustion Controls, including Low NOx Burners (LNBs) with Overfire Air (OFA)
   * Selective Non-Catalytic Reduction (SNCR)
   * Selective Catalytic Reduction (SCR)

Estimates were based upon an initial average annual NOx level equal to 2001-2003 historical rates (average of annual average for each of the three years) when advanced combustion controls were not in use at these units.  Emission rates with combustion controls were estimated from more recent data: the lower of 2011 annual emission rate or the average of 2012 Q1 and Q2, or, where there is no available operating data with combustion controls, a projected emission rate.   2001-2003 historical data were also used to estimate annual heat input and the associated capacity factor for each unit; these estimates are used in all calculations.

In estimating the cost of controls, the following were considered:
   * IPM Cost models
   * US EPA Air Pollution Control Cost Manual
   * Data provided by the facilities
   * Other data that have been published and are described in more detail
      
The BART guidelines recommend use of the EPA Air Pollution Control Cost Manual, and the methodology used here for estimating costs is consistent with the recommendations in the manual, such as inclusion of taxes, insurance and administrative costs, and the use of overnight cost for capital cost.

Combustion Controls
For combustion controls, if the capital and operating cost estimates by the users were available, they were used.  If not, IPM models were used to estimate capital and operating costs of combustion controls.  Percent reduction and tons of NOx removed were based upon actual emission rates after control installation or projected emission rates if actual emission rates were not available.  Fixed and variable operating costs of combustion controls were estimated from IPM algorithms.

SNCR
For SNCR, capital cost is assumed to be $20/kW.  According to the 2008 Institute of Clean Air Companies' SNCR White Paper, "Typical SNCR capital costs for utility applications are $5-$15/kW, vendor scope, which corresponds to a maximum of $20/kW if balance-of-plant capital requirements are included."    This is also consistent with my personal experience, having worked with the following electric utilities and power plants on their SNCR installations as a consultant or as a past employee of Research-Cottrell and Fuel Tech  -  suppliers of SNCR systems.
   * Constellation Energy  -  C P Crane units 1&2 and Wagner Unit 2 
   * Conectiv  -  Edge Moor unit 3 and Indian River 
   * New England Power  -  Salem Harbor Station 
   * Montaup Electric  -  Somerset Unit 8 

And, I have also published reports that describe the cost and application of technologies used for control of NOx, including SNCR.,  
Therefore, $20/kW provides a reasonable estimate for the capital cost of SNCR.  Furthermore, due to the low capital cost of SNCR, the operating cost  -  especially reagent cost  -  is the much more important component of cost.
SNCR reagent consumption and the level of NOx reduction are very dependent upon a number of factors  -  such as initial NOx level and furnace temperatures.  It was not possible to evaluate all of the relevant factors because detailed furnace characteristics were not available.  Figure 1 is an example of test data from an SNCR optimization program on a pulverized coal fired boiler that shows NOx reduction and chemical utilization versus Normalized Stoichiometric Ratio (NSR  -  a measure of chemical treatment rate).  Chemical utilization equals per cent reduction divided by NSR and is a measure of the efficiency of reagent use.  The data include data from optimized as well as unoptimized configurations, which is why some of the data points fall below the curves.  The curves that would be developed for any given unit will vary from one unit to another and, while having similar shapes as those in Figure 1, may have somewhat different values.  For the purpose of making an estimate of reagent consumption for the Wyoming pulverized coal  units it was assumed that the chemical utilization was 25% and that NOx reduction diminished with lower NOx concentrations  -  30% for NOx greater than 0.25 lb/MMBtu, 25% for NOx between 0.20 and 0.25 lb/MMBtu, and 20% for NOx under 0.20 lb/MMBtu.  This is expected to provide a reasonable estimate of NOx reduction and reagent consumption.
Other elements of SNCR variable operating cost and fixed operating cost are estimated using IPM algorithms.

Figure 1.  NOx Reduction and Reagent Utilization versus reagent treatment rate in NSR for a Pulverized Coal Fired Boiler during an SNCR optimization program 
      (Data points plotted below the curves are at unoptimized conditions)  
                                       

SCR
Selective Catalytic NOx Reduction (SCR) capital cost is estimated using the IPM algorithms with retrofit factors adjusted on a unit by unit basis.  The retrofit factor is a subjective factor used to account for the estimated difficulty of the retrofit that is unique to the facility.  Because site visits were not possible, the retrofit factor was estimated from satellite images that provide some insight to the configuration of the units and degree of congestion around the site and in the vicinity of where the SCR would be installed.  These factors impact the ability to locate large cranes on the site  -  that impact how the SCR is assembled (are large sections lifted into place or is the SCR "stick built"), how much ductwork is needed, if the SCR must be built onto a large, elevated steel structure or can be built near the ground, and if other equipment must be relocated to accommodate the space of the SCR.    When using the IPM capital cost model, retrofit difficulties associated with an SCR may result in capital cost increases of 30 to 50% over the base model. 

In addition, historical industry cost data were considered to determine if the costs were reasonable in the context of what has been reported at other facilities.7, ,   Estimates were also compared against estimates provided by the facility owners (both December 2007 and March 2008 estimates for Dave Johnston, Naughton and Wyodak, and June 2008 for Laramie River).   For Dave Johnston, Naughton and Wyodak units the estimated capital cost of SCR provided by the owners for the five units increased by roughly 60% between these two dates, and I did not see an explanation for the increase in cost.

            Table 1.  Owner's estimates of capital cost for SCR*
              (see workbook: WY EGU BART_RP Costs_20121019.xlsx)

Plant
                                 Dave Johnston
                                   Naughton
                                 Laramie River
                                    Wyodak
Unit
                                     BW43
                                     BW44
                                       1
                                       2
                                       3
                                      1-3
                                     BW91
Capacity, MW
                                      220
                                      330
                                      160
                                      210
                                      330
                                      565
                                      335
Dec 2007 $/kW SCR
                                     $306
                                     $300
                                     $318
                                     $312
                                     $279
                                       
                                     $296
March/July 2008 $/kW SCR
                                     $510
                                     $436
                                     $531
                                     $509
                                     $415
                                     $218
                                     $474
4 month % increase
                                      66%
                                      46%
                                      67%
                                      63%
                                      49%
                                       
                                      60%
* Costs include owner's cost and Allowance for Funds Used During Construction (AFUDC)
  
Figure 2 is taken from Cichanowicz, and shows the industry-reported costs for SCRs at different time periods, including 2008-2010.  Note that, as shown on Figure 2, all costs have been normalized to a 2008 basis.  In addition, these costs are on the same basis as those shown above (inclusive of owner's costs, AFUDC, etc.).  As shown, the Wyoming owner's estimates in Table 1 for December 2007 were in the same range as the actuals reported by Cichanowicz for installations which occurred between 2008 and 2010 ($125/kW to $450/kW), but the capital costs reported only four months later for Dave Johnston, Naughton and Wyodak (all owned by Pacificorp) were near or well above the highest costs (in $/kW) reported by Cichanowicz in the 2008-2010 period.   The dramatic increase in estimated cost between December 2007 and March 2008 for the Pacificorp units and the stark inconsistency of the March 2008 estimated costs with other industry data begs more explanation from the owners about their reported costs.  The SCR cost estimate from Basin Electric for the Laramie River units was consistent with what industry had reported.

Figure 2 also demonstrates two other points  - 
   * The scatter in cost shows that SCR capital cost is a strong function of site conditions as well as capacity, and this is why a retrofit factor is important.
   * SCR costs have increased significantly between 2000 and the 2008-2010 period.

Regarding the first point, the IPM documentation states that "Retrofit difficulties associated with an SCR may result in capital cost increases of 30 to 50% over the base model. "    So, retrofit factors up to 1.5 were used in my cost estimates.

Regarding the second point, this is supported by the increase in the Chemical Engineering Plant Cost Index (CEPCI) between 2000 and 2007, as shown in Figure 3.  However, between 2006 and 2012 the annual CEPCI has remained in a range between about 500 and 600 (550+-10%), and the monthly CEPCI peaked in August 2008 at 619.3.  The July 2012 CEPCI, recently published in the October 2012 issue of Chemical Engineering, was reported to be 582.2 and is shown as the 2012 value on Figure 3.  Therefore, the rapid escalation of cost that was experienced after 2003 and peaked in August 2008 has slowed down appreciably.
Figure 2.  Capital cost of SCRs (in $/kW) for four different time periods, reported by Cichanowicz
                                       
        Figure 3.  Annual Chemical Engineering Plant Cost Index (CEPCI)
                         Chemical Engineering magazine
                                       
Assumptions

In estimating cost of control, it is assumed that a full complement of combustion controls are implemented prior to installation of post-combustion controls (SNCR and SCR).  Emissions rates for the 2001-2003 period were used to estimate the emission rate prior to installation of combustion controls.
The average reported emission rates for 2001-2003, 2011 and 2012 year-to-date are shown in Table 2 with Wyoming's proposed BART limit.   Except for Dave Johnston units 1 and 2, there has been some significant NOx reduction since 2003 at these facilities through implementation of combustion NOx controls.  The most recent NOx reductions occurred at Naughton plant in 2012.  For Naughton 1, Separated Overfire Air was installed in June, which is why the reduction in NOx is not yet reflected in the six months of data for 2012.  It is assumed that Naughton 1 will achieve the same NOx emissions rate as Naughton 2 since they are both tangential furnaces, both have similar NOx emissions prior to the installation of controls and, according to the Wyoming BART proposed limits, are projected to have similar emission rates after the installation of controls.  For Naughton 3, it is assumed that the annual average emission rate with combustion controls will be 0.33 lb/MMBtu  -  roughly 10% lower than the expected 30-day average with combustion controls in Wyoming's proposed SIP.
Cost Estimating
The cost estimates summarized in the following sections of this memo are detailed in a Microsoft Excel workbook WY_EGU_BART_RP_Costs_20121019.xlsx that is an attachment to this memo.  The details of the estimating methods are described in the workbook.  Consistent with the EPA Control Cost Manual, capital cost estimates do not include AFUDC or Owner's Costs.  With regard to capital cost escalation, as demonstrated in Figure 3, the CEPCI has remained in a range of about 550 +- 50 since 2006.  Since all of the capital cost estimates and algorithms that are utilized in this effort were developed since 2006, escalation has been modest, and was adjusted for in some cases.
Table 2.  Reported emission rates and Wyoming proposed BART limits for affected EGUs
                                 Facility Name
                             Facility ID (ORISPL)
                                    Unit ID
                           Annual Heat Input, MMBtu
                                 2001-03 avg.
                           Avg. NOx Rate (lb/MMBtu)
                                       
                                       
                                       
                                       
                                   2001-2003
                                     2011
                                   2012 YTD
                         Wyoming Proposed BART limit *
Dave Johnston
                                     4158
                                     BW41
                                   9,618,309
                                    0.4549
                                    0.3864
                                    0.3934
                                     none
Dave Johnston
                                     4158
                                     BW42
                                   9,810,184
                                    0.4406
                                    0.4273
                                    0.4328
                                     none
Dave Johnston
                                     4158
                                     BW43
                                  19,209,226
                                    0.5116
                                    0.2261
                                    0.2162
                                     0.28
Dave Johnston
                                     4158
                                     BW44
                                  27,687,905
                                    0.3662
                                    0.1413
                                    0.2039
                                     0.15
Laramie River
                                     6204
                                       1
                                  46,814,433
                                    0.2585
                                    0.1843
                                   0.1930**
                                     0.23
Laramie River
                                     6204
                                       2
                                  46,557,737
                                    0.2703
                                    0.1838
                                    0.1901
                                     0.21
Laramie River
                                     6204
                                       3
                                  47,765,529
                                    0.2669
                                    0.2174
                                    0.1930
                                     0.21
Naughton
                                     4162
                                       1
                                  13,787,157
                                    0.5155
                                    0.5892
                                    0.5551
                                     0.26
Naughton
                                     4162
                                       2
                                  16,616,431
                                    0.5221
                                    0.5641
                                    0.2108
                                     0.26
Naughton
                                     4162
                                       3
                                  24,856,366
                                    0.3656
                                    0.4333
                                    0.3984
                                     0.07
Wyodak
                                     6101
                                     BW91
                                  35,204,108
                                    0.2622
                                    0.2062
                                    0.1918
                                     0.23
All historical emissions and heat input data developed from Air Markets Program Data.  For 2012 YTD for Laramie River and Wyodak nine months of data was available, for others only six months of data was available 
* either 12 month or 30 day rolling average, depending upon facility
** April and May 2012 data was excluded for LR1 due to apparent shutdown and/or use of natural gas
                                       
For combustion controls, capital and operating costs were based upon what was in the Wyoming proposed SIP supporting attachments, when available.  In the case of Dave Johnston 1 and 2, the IPM cost estimating algorithms were used for combustion control capital and operating costs and the CEPCI was used to escalate from 2007 dollars to 2010 dollars.
For SNCR, the capital cost was assumed to be $20/kW.  Regent consumption was determined using a chemical utilization factor of 0.25.  After combustion controls, SNCR can typically achieve NOx reductions of 20% to 30%.   NOx reduction with SNCR is known to be greater at higher NOx emission rates than lower rates. NOx reduction was estimated as 30% for initial NOx greater than 0.25 lb/MMBtu, 25% for NOx from 0.20 to 0.25 lb/MMBtu and 20% for NOx less than 0.20 lb/MMBtu. 
For consumables, notably urea, there has been significant variability in cost, and current cost estimates were used (delivered price of about $450/ton for 50% by weight solution).   Unfortunately, the cost of urea has increased significantly, as indicated in Figure 4, an index that is indicative of the price of urea paid to producers (not including transport, etc.).  As shown, producer prices have roughly doubled in the past three years.  "Improvement" as used in the figure, means increasing prices for producers.
                                       
                   Figure 4.  Profercy World Nitrogen Index.
               www.fertilizerworks.com/html/market/profercy.pdf
                                       

Dave Johnston, Units 1-4

An overhead view of Dave Johnston plant is shown in Figure 5.  Dave Johnson 1 and 2 do not have NOx controls.  Units 3 and 4 are equipped with combustion NOx controls and no post-combustion controls.  
Units 1 and 2 are dry bottom wall fired units and combustion control retrofits on such units are relatively routine.   For units 1 and 2 EPA estimated emission rates are 0.20 lb/MMBtu (annual average) in the proposal in the Federal Register, and this is reasonable for LNBs with OFA (about 55% NOx reduction).   For units 3 and 4, Wyoming's analysis estimated an emission rate of 0.28 lb/MMBtu and 0.15 lb/MMBtu (30-day average) with LNB and OFA for units 3 and 4, respectively.  Units 3 and 4 have already installed combustion controls as reflected in 2011 annual average NOx emission rates of 0.23 lb/MMBtu and 0.14 lb/MMBtu, respectively.
Retrofit costs
Retrofit costs for combustion controls and SNCR are expected to be consistent with other similar units.  Retrofit costs for combustion controls are based upon company estimates for Units 3 and 4.  However, since the company did not provide costs for Units 1 and 2, IPM cost estimates were used.  For SNCR a presumed capital cost of $20/kW is assumed.
It was previously determined that post-combustion NOx controls, including SCR, are feasible, but they were not selected in Wyoming's proposal as BART due to cost.14  Based upon the close proximity of the boilers and associated equipment (including, decommissioned chimneys) to one another, and the coal pile, retrofit of an SCR on Units 1-3 would likely entail a significantly higher than average retrofit cost.  There may be more space available near unit 4 for a retrofit of SCR, but this is unclear from the photograph.   For these reasons, the estimates of capital cost shown in Table 3 are adjusted for retrofit difficulty using subjective factors that are integrated into the IPM cost estimating algorithms and a retrofit difficulty factor of 1.5 is assumed for all units.

                      Figure 5. Dave Johnston Power Plant
                                       

                Table 3. David Johnston Estimated Control Costs
DJ 1
                        Cost from 2003 emission levels
 
                              Combustion Control
                                     (CC)
                                  CC and SNCR
                                  CC and SCR
Capital Cost, $/kW
                                                                            $93
                                                                           $113
                                                                           $439
Control Efficiency
                                                                            56%
                                                                            67%
                                                                            89%
Uncontrolled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                            536
                                                                            536
                                                                            536
NOx Rate (lb/MMBtu) 
                                                                           0.45
                                                                           0.45
                                                                           0.45
NOx (TPY)  
                                                                           2188
                                                                           2188
                                                                           2188
Controlled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                            236
                                                                         176.82
                                                                          58.94
NOx Rate (lb/MMBtu) 
                                                                           0.20
                                                                           0.15
                                                                           0.05
NOx (TPY)  
                                                                            962
                                                                         721.37
                                                                         240.46
 
                                                                              
                                                                              
                                                                              
Tons/Year Removed  
                                                                           1226
                                                                        1466.31
                                                                        1947.23
 
                                                                              
                                                                              
                                                                              
Total Cost/year
                                                                     $1,187,179
                                                                     $2,087,189
                                                                     $6,417,536
$/Ton  
                                                                           $968
                                                                         $1,423
                                                                         $3,296
$/ton Incremental
                                                                              
                                                                         $3,743
                                                                         $9,004
 DJ 2
                        Cost from 2003 emission levels
 
                              Combustion Control
                                     (CC)
                                  CC and SNCR
                                  CC and SCR
Capital Cost, $/kW  
                                                                            $93
                                                                           $113
                                                                           $439
Control Efficiency
                                                                            55%
                                                                            66%
                                                                            89%
Uncontrolled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                            519
                                                                            519
                                                                            519
NOx Rate (lb/MMBtu) 
                                                                           0.44
                                                                           0.44
                                                                           0.44
NOx (TPY)  
                                                                           2161
                                                                          2,161
                                                                          2,161
Controlled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                            236
                                                                            177
                                                                             59
NOx Rate (lb/MMBtu) 
                                                                           0.20
                                                                           0.15
                                                                           0.05
NOx (TPY)  
                                                                            981
                                                                            736
                                                                            245
 
                                                                              
                                                                              
                                                                              
Tons/Year Removed  
                                                                           1180
                                                                          1,425
                                                                          1,916
 
                                                                              
                                                                              
                                                                              
Total Cost/year
                                                                     $1,188,797
                                                                     $2,100,619
                                                                     $6,432,035
$/Ton  
                                                                         $1,007
                                                                         $1,474
                                                                         $3,357
$/ton Incremental
                                                                              
                                                                         $3,718
                                                                         $8,830
                Table 3. David Johnston Estimated Control Costs
DJ 3
                        Cost from 2003 emission levels
 
                              Combustion Control
                                     (CC)
                                  CC and SNCR
                                  CC and SCR
Capital Cost, $/kW  
                                                                            $73
                                                                            $93
                                                                           $378
Control Efficiency
                                                                            58%
                                                                            68%
                                                                            90%
Uncontrolled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                           1249
                                                                           1249
                                                                           1249
NOx Rate (lb/MMBtu) 
                                                                           0.51
                                                                           0.51
                                                                           0.51
NOx (TPY)  
                                                                           4913
                                                                          4,913
                                                                          4,913
Controlled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                            528
                                                                            396
                                                                            122
NOx Rate (lb/MMBtu) 
                                                                           0.22
                                                                           0.16
                                                                           0.05
NOx (TPY)  
                                                                           2077
                                                                          1,558
                                                                            480
 
                                                                              
                                                                              
                                                                              
Tons/Year Removed  
                                                                           2837
                                                                          3,356
                                                                          4,433
 
                                                                              
                                                                              
                                                                              
Total Cost/year
                                                                     $1,699,807
                                                                     $3,545,435
                                                                    $11,262,188
$/Ton  
                                                                           $599
                                                                         $1,057
                                                                         $2,540
$/ton Incremental
                                                                              
                                                                         $3,555
                                                                         $7,163
DJ 4
                        Cost from 2003 emission levels
 
                              Combustion Control
                                     (CC)
                                  CC and SNCR
                                  CC and SCR
Capital Cost, $/kW  
                                                                            $22
                                                                            $42
                                                                           $297
Control Efficiency
                                                                            61%
                                                                            69%
                                                                            86%
Uncontrolled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                           1325
                                                                           1325
                                                                           1325
NOx Rate (lb/MMBtu) 
                                                                           0.37
                                                                           0.37
                                                                           0.37
NOx (TPY)  
                                                                           5070
                                                                          5,070
                                                                          5,070
Controlled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                            511
                                                                            409
                                                                            181
NOx Rate (lb/MMBtu) 
                                                                           0.14
                                                                           0.11
                                                                           0.05
NOx (TPY)  
                                                                           1956
                                                                          1,565
                                                                            692
 
                                                                              
                                                                              
                                                                              
Tons/Year Removed  
                                                                           3114
                                                                          3,505
                                                                          4,377
 
                                                                              
                                                                              
                                                                              
Total Cost/year
                                                                       $767,342
                                                                     $2,592,288
                                                                    $13,021,894
$/Ton  
                                                                           $246
                                                                           $740
                                                                         $2,975
$/ton Incremental
                                                                              
                                                                         $4,665
                                                                        $11,951
Laramie River Units 1-3
The Laramie River plant has three roughly 570 MW units.  All are dry bottom wall fired boilers and currently are equipped with LNBs and OFA and averaged under 0.20 lb/MMBtu in 2012 through September.  
Retrofit Costs
For SNCR a presumed capital cost of $20/kW is assumed.  SNCR does not require much space and retrofit difficulty does not vary much for SNCR.
The plant is shown in Figures 6a and b.  These figures show a much less constrained site than Dave Johnston.  As a result, retrofit difficulty of installing SCR is expected to be average, except possibly for unit 2 which is located between units 1 and 3.  Access of a crane will be somewhat more challenging for unit 2 and an SCR retrofit difficulty of 1.2 is assumed for estimating SCR capital cost.  In all cases the SCR reactor is likely to be installed above the ESP ductwork.
The Wyoming analysis indicated that NOx should be reduced to around 0.18+-0.02 lb/MMBtu with LNB and OFA and suggested a 30-day rolling average rate of 0.23 lb/MMBtu.   Actual emission levels at the plant for the first nine months of 2012 for all three units are about 0.19 lb/MMBtu, which is an indication of what is expected on an annual average basis.   Units 1 and 2 had even lower annual average emission rates in 2011 at about 0.18 lb/MMBtu and Unit 3 was somewhat higher just under 0.22 lb/MMBtu, with the average of the three units combined at about 0.195 lb/MMBtu annual average.   The Wyoming document also suggests that addition of SNCR would reduce NOx to 0.12 lb/MMBtu (assumedly on a 30-day rolling average basis).  This is greater NOx reduction from SNCR than expected and is inconsistent with other experience.   Fuel Tech, the leading supplier of SNCR, was contacted and confirmed that an emission reduction of about 20% is expected from SNCR at these NOx levels, which suggests an annual emission rate close to 0.15 lb/MMBtu with SNCR from an annual rate of about 0.19 lb/MMBtu without SNCR. 
The cost analysis of Table 4 shows slightly different costs for the three Laramie River units, although they are similar boilers.  This is in part due to the units having slightly different starting NOx levels, which affect the costs.  In addition, according to NEEDS data, unit 1 has slightly lower capacity than units 2 and 3 (565 MW versus 570 MW).  NEEDS also indicated slightly different heat rates for the units, which impact capacity factors and tons of NOx emitted.  Finally, a modestly higher SCR retrofit difficulty factor is assumed for unit 2 because access will be poorer than for units 1 or 3.

                      Figure 6a.  Laramie River Units 1-3
                                       

                      Figure 6b.  Laramie River Units 1-3
                                       

                Table 4. Laramie River Estimated Control Costs
LR 1
                        Cost from 2003 emission levels
 
                              Combustion Control
                                     (CC)
                                  CC and SNCR
                                  CC and SCR
Capital Cost, $/kW  
                                                                            $37
                                                                            $57
                                                                           $219
Control Efficiency
                                                                            26%
                                                                            41%
                                                                            81%
Uncontrolled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                           1652
                                                                           1652
                                                                           1652
NOx Rate (lb/MMBtu) 
                                                                           0.26
                                                                           0.26
                                                                           0.26
NOx (TPY)  
                                                                           6051
                                                                          6,051
                                                                          6,051
Controlled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                           1227
                                                                            982
                                                                            320
NOx Rate (lb/MMBtu) 
                                                                           0.19
                                                                           0.15
                                                                           0.05
NOx (TPY)  
                                                                           4495
                                                                          3,596
                                                                          1,170
 
                                                                              
                                                                              
                                                                              
Tons/Year Removed  
                                                                           1556
                                                                          2,455
                                                                          4,880
 
                                                                              
                                                                              
                                                                              
Total Cost/year
                                                                     $2,268,806
                                                                     $5,880,822
                                                                    $18,146,629
$/Ton  
                                                                         $1,458
                                                                         $2,395
                                                                         $3,718
$/ton Incremental
                                                                              
                                                                         $4,018
                                                                         $5,057
LR 2
                        Cost from 2003 emission levels
 
                              Combustion Control
                                     (CC)
                                  CC and SNCR
                                  CC and SCR
Capital Cost, $/kW  
                                                                            $37
                                                                            $57
                                                                           $247
Control Efficiency
                                                                            29%
                                                                            43%
                                                                            82%
Uncontrolled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                           1688
                                                                           1688
                                                                           1688
NOx Rate (lb/MMBtu) 
                                                                           0.27
                                                                           0.27
                                                                           0.27
NOx (TPY)  
                                                                           6293
                                                                          6,293
                                                                          6,293
Controlled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                           1199
                                                                            959
                                                                            312
NOx Rate (lb/MMBtu) 
                                                                           0.19
                                                                           0.15
                                                                           0.05
NOx (TPY)  
                                                                           4470
                                                                          3,576
                                                                          1,164
 
                                                                              
                                                                              
                                                                              
Tons/Year Removed  
                                                                           1823
                                                                          2,717
                                                                          5,129
 
                                                                              
                                                                              
                                                                              
Total Cost/year
                                                                     $2,268,806
                                                                     $5,884,257
                                                                    $20,017,988
$/Ton  
                                                                         $1,244
                                                                         $2,166
                                                                         $3,903
$/ton Incremental
                                                                              
                                                                         $4,044
                                                                         $5,860

                Table 4. Laramie River Estimated Control Costs
LR 3
                        Cost from 2003 emission levels
 
                              Combustion Control
                                     (CC)
                                  CC and SNCR
                                  CC and SCR
Capital Cost, $/kW  
                                                                            $37
                                                                            $57
                                                                           $223
Control Efficiency
                                                                            28%
                                                                            42%
                                                                            81%
Uncontrolled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                           1778
                                                                           1778
                                                                           1778
NOx Rate (lb/MMBtu) 
                                                                           0.27
                                                                           0.27
                                                                           0.27
NOx (TPY)  
                                                                           6375
                                                                          6,375
                                                                          6,375
Controlled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                           1279
                                                                           1023
                                                                            333
NOx Rate (lb/MMBtu) 
                                                                           0.19
                                                                           0.15
                                                                           0.05
NOx (TPY)  
                                                                           4586
                                                                          3,669
                                                                          1,194
 
                                                                              
                                                                              
                                                                              
Tons/Year Removed  
                                                                           1789
                                                                          2,706
                                                                          5,181
 
                                                                              
                                                                              
                                                                              
Total Cost/year
                                                                     $2,268,806
                                                                     $5,933,791
                                                                    $18,597,027
$/Ton  
                                                                         $1,268
                                                                         $2,192
                                                                         $3,589
$/ton Incremental
                                                                              
                                                                         $3,996
                                                                         $5,117

Naughton Units 1-3

The Naughton units 1, 2 and 3 are 160 MW, 210 MW and 330 MW, respectively.  All are tangentially fired and have recently installed combustion controls.  The reported emissions levels shown in Table 2 do not yet fully reflect the anticipated NOx reductions from combustion controls.  It is assumed that Naughton Units 1 and 2 will achieve similar rates with controls, about 0.21 lb/MMBtu annual average.   It is assumed that Naughton Unit 3 will achieve 0.33 lb/MMBtu annual average since that is 10% lower than the 0.37 lb/MMBtu presumed 30 day average by Wyoming, thereby accounting for the longer averaging period.

Retrofit costs

Naughton Units 1-3 are shown in Figure 7.  Like the other plants, SNCR costs are assumed to be $20/kW.  

If SCR were installed on units 1 and 2 it may be necessary to install an SCR reactor above the ESP and on the other side of the retired chimney from the boiler.  In such a case, the ductwork from the economizer to the SCR and from the SCR to the air preheater inlet would be longer than usual for a high dust SCR and would need to go around the retired chimneys.  For unit 3 it is also unclear if there is enough space to install the SCR reactor on the same side of the chimney as the boiler, which, like Units 1 and 2, impacts the length of ductwork that would be needed.  There appears to be access for construction equipment, such as a crane, in the area east of the plant (the upper part of the photo).  In estimating the cost of the SCR, I assume that the retrofit difficulty is above average, and an assumed retrofit difficulty factor of 1.3 is assumed.  Results of cost calculations are shown in Table 5.
                         Figure 7.  Naughton Units 1-3
                                       
                                       - 
                   Table 5. Naughton Estimated Control Costs
N 1
                        Cost from 2003 emission levels
 
                              Combustion Control
                                     (CC)
                                  CC and SNCR
                                  CC and SCR
Capital Cost, $/kW  
                                                                            $55
                                                                            $75
                                                                           $330
Control Efficiency
                                                                            59%
                                                                            69%
                                                                            90%
Uncontrolled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                            895
                                                                            895
                                                                            895
NOx Rate (lb/MMBtu) 
                                                                           0.52
                                                                           0.52
                                                                           0.52
NOx (TPY)  
                                                                           3553
                                                                           3553
                                                                           3553
Controlled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                            366
                                                                            274
                                                                             87
NOx Rate (lb/MMBtu) 
                                                                           0.21
                                                                           0.16
                                                                           0.05
NOx (TPY)  
                                                                           1453
                                                                           1090
                                                                            345
 
                                                                              
                                                                              
                                                                              
Tons/Year Removed  
                                                                           2100
                                                                           2463
                                                                           3209
 
                                                                              
                                                                              
                                                                              
Total Cost/year
                                                                       $932,466
                                                                     $2,258,826
                                                                     $7,437,269
$/Ton  
                                                                           $444
                                                                           $917
                                                                         $2,318
$/ton Incremental
                                                                              
                                                                         $3,650
                                                                         $6,947
N 2
                        Cost from 2003 emission levels
 
                              Combustion Control
                                     (CC)
                                  CC and SNCR
                                  CC and SCR
Capital Cost, $/kW  
                                                                            $40
                                                                            $60
                                                                           $300
Control Efficiency
                                                                            60%
                                                                            70%
                                                                            90%
Uncontrolled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                           1174
                                                                           1174
                                                                           1174
NOx Rate (lb/MMBtu) 
                                                                           0.52
                                                                           0.52
                                                                           0.52
NOx (TPY)  
                                                                           4337
                                                                           4337
                                                                           4337
Controlled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                            474
                                                                            356
                                                                            112
NOx Rate (lb/MMBtu) 
                                                                           0.21
                                                                           0.16
                                                                           0.05
NOx (TPY)  
                                                                           1752
                                                                           1314
                                                                            415
 
                                                                              
                                                                              
                                                                              
Tons/Year Removed  
                                                                           2586
                                                                           3024
                                                                           3922
 
                                                                              
                                                                              
                                                                              
Total Cost/year
                                                                       $883,900
                                                                     $2,510,049
                                                                     $8,843,387
$/Ton  
                                                                           $342
                                                                           $830
                                                                         $2,255
$/ton Incremental
                                                                              
                                                                         $3,713
                                                                         $7,050

                   Table 5. Naughton Estimated Control Costs
N 3
                        Cost from 2003 emission levels
 
                              Combustion Control
                                     (CC)
                                  CC and SNCR
                                  CC and SCR
Capital Cost, $/kW  
                                                                             $3
                                                                            $23
                                                                           $247
Control Efficiency
                                                                            10%
                                                                            37%
                                                                            86%
Uncontrolled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                           1266
                                                                           1266
                                                                           1266
NOx Rate (lb/MMBtu) 
                                                                           0.37
                                                                           0.37
                                                                           0.37
NOx (TPY)  
                                                                           4544
                                                                           4544
                                                                           4544
Controlled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                              
                                                                            800
                                                                            173
NOx Rate (lb/MMBtu) 
                                                                           0.33
                                                                           0.23
                                                                           0.05
NOx (TPY)  
                                                                           4101
                                                                           2871
                                                                            621
 
                                                                              
                                                                              
                                                                              
Tons/Year Removed  
                                                                            442
                                                                           1673
                                                                           3922
 
                                                                              
                                                                              
                                                                              
Total Cost/year
                                                                       $106,393
                                                                     $3,896,839
                                                                    $12,718,731
$/Ton  
                                                                           $240
                                                                         $2,329
                                                                         $3,243
$/ton Incremental
                                                                               
                                                                         $3,081
                                                                         $3,922

Wyodak

Wyodak Power Plant is located on the Wyodak Energy Complex that includes the Wygen units 1-3 and Neil Simpson units 1, 2.  Wyodak is a 335 MW dry bottom wall-fired unit equipped with low NOx burners and overfire air.  In 2011 the annual average NOx emission was under 0.21 lb/MMBtu and the average for the first nine months of 2012 was under 0.20 lb/MMBtu.  Additional NOx controls would likely entail SNCR or SCR.

Retrofit costs
As with the other plants, SNCR is assumed to cost $20/kW to install.
In the event SCR were installed at the site, the SCR reactor would likely be located above the existing (but decommissioned) ESP shown between the boiler building and the chimney in Figure 8.  There is ample room on the site for lay down of material.  Location of a crane near the construction site appears to be possible.  Therefore, the difficulty of this retrofit is probably average to above average since it is common to have some amount of relocation of equipment.  A conservative estimate of retrofit difficulty is 1.3.
Table 6 shows the results of cost calculations.

                         Figure 8.  Wyodak Power Plant

                    Table 6. Wyodak Estimated Control Costs
                                       
                        Cost from 2003 emission levels
 
                              Combustion Control
                                     (CC)
                                  CC and SNCR
                                  CC and SCR
Capital Cost, $/kW
                                                                            $36
                                                                            $56
                                                                           $302
Control Efficiency
                                                                            27%
                                                                            41%
                                                                            81%
Uncontrolled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                           1060
                                                                           1060
                                                                           1060
NOx Rate (lb/MMBtu) 
                                                                           0.26
                                                                           0.26
                                                                           0.26
NOx (TPY)  
                                                                           4615
                                                                          4,615
                                                                          4,615
Controlled Rate
                                                                              
                                                                              
                                                                              
NOx Rate (lb/hr)  
                                                                            775
                                                                            620
                                                                            202
NOx Rate (lb/MMBtu) 
                                                                           0.19
                                                                           0.15
                                                                           0.05
NOx (TPY)  
                                                                           3376
                                                                          2,701
                                                                            880
 
                                                                              
                                                                              
                                                                              
Tons/Year Removed  
                                                                           1239
                                                                          1,914
                                                                          3,735
 
                                                                              
                                                                              
                                                                              
Total Cost/year
                                                                     $1,272,427
                                                                     $3,787,466
                                                                    $14,386,417
$/Ton  
                                                                         $1,027
                                                                         $1,979
                                                                         $3,852
$/ton Incremental
                                                                              
                                                                         $3,725
                                                                         $5,822