EPA Annual Cost $28,740,000 Table 15 of TSD EPA tons per year reduced 10,427 assumes 77.8% capacity factor used by APS (see cap factor tab), 0.49 to 0.098 lb/MMBtu, heat rate = 7806 mmbtu/hr

Unit 5 NOx Control Total Annual Cost tpy reduced APS incremental cost All Options SCR to LNB+OFA* Dominant Options **SCR** $39,925,221 11,445 $5,443 $4,770 $5,443 ROTAMIX+ROFA LNB+OFA+HERT **SNCR + LNB + OFA** $11,221,000 6,171 -$178 $3,276 ROFA ROTAMIX + LNB SNCR + LNB $11,503,000 4,589 $10,185 **LNB + OFA** $3,447,000 3,798 $552 $979 LNB $1,991,000 1,160 $4,387 ROTAMIX SNCR $10,668,000 3,138 $4,120 **COS** $348,000 633
SCR costs from APS taken from Table 14 of October 2010 TSD (most recent cost estimates) All other costs taken from Table 5 of TSD, costs dated August 2008 TPY reductions estimated by APS taken from Table 7 of TSD Dominant Options are shown in Bold Face font, and were determined from the least cost envelope charts
* We also show incremental costs against the technology APS determined was BART for each unit ** EPA determined that controls relying on LNB or OFA (highlighted in grey) will not be effective on Unit 5 due to limitations in the boiler configuration, as discussed in the TSD (see p 19)assumes 77.8% capacity factor used by APS (see cap factor tab), 0.49 to 0.098 lb/MMBtu, heat rate = 7806 mmbtu/hr

EPA incremental cost average cost effectiveness SCR to SNCR** SCR to LNB+OFA

$2,479 $3,815 $3,488

APS incremenal cost SCR to SNCR** SCR to LNB+OFA $1,818

$3,522 $4,770
$2,507 $908 $1,716
$3,400 $550

** EPA determined that controls relying on LNB or OFA (highlighted in grey) will not be effective on Unit 5 due to limitations in the boiler configuration, as discussed in the TSD (see p 19)EPA Annual Cost $28,740,000 Table 15 of TSD EPA tons per year reduced 10,427 assumes 77.8% capacity factor used by APS (see cap factor tab), 0.49 to 0.098 lb/MMBtu, heat rate = 7806 mmbtu/hr

Unit 4 NOx Control Total Annual Cost tpy reduced APS incremental cost All options SCR to LNB+OFA* Dominant Options **SCR** $43,587,221 11,445 $6,137 $5,249 $6,137 ROTAMIX+ROFA LNB+OFA+HERT **SNCR + LNB + OFA** $11,221,000 6,171 -$178 $3,276 ROFA ROTAMIX + LNB SNCR + LNB $11,503,000 4,589 $10,185 **LNB + OFA** $3,447,000 3,798 $552 $979 LNB $1,991,000 1,160 $4,387 ROTAMIX SNCR $10,668,000 3,138 $4,120 **COS** $348,000 633
SCR costs from APS taken from Table 14 of October 2010 TSD (most recent cost estimates) All other costs taken from Table 5 of TSD, costs dated August 2008 TPY reductions estimated by APS taken from Table 7 of TSD Dominant Options are shown in Bold Face font, and were determined from the least cost envelope charts
* We also show incremental costs against the technology APS determined was BART for each unit ** EPA determined that controls relying on LNB or OFA (highlighted in grey) will not be effective on Unit 4 due to limitations in the boiler configuration, as discussed in the TSD (see p 19)assumes 77.8% capacity factor used by APS (see cap factor tab), 0.49 to 0.098 lb/MMBtu, heat rate = 7806 mmbtu/hr

EPA incremental cost average cost effectiveness SCR to SNCR** SCR to LNB+OFA

$2,479 $3,815 $3,808

APS incremenal cost SCR to SNCR** SCR to LNB+OFA $1,818

$3,963 $5,249
$2,507 $908 $1,716
$3,400 $550

** EPA determined that controls relying on LNB or OFA (highlighted in grey) will not be effective on Unit 4 due to limitations in the boiler configuration, as discussed in the TSD (see p 19)EPA Annual Cost $12,068,000 Table 15 of TSD EPA tons per year reduced 4,505 assumes 90.8% capacity factor used by APS, 0.59 to 0.118 lb/MMBtu, heat rate = 2400 mmbtu/hr

Unit 3 NOx Control Total Annual Cost tpy reduced APS incremental cost All Options SCR to LNB+OFA* **SCR** $19,962,000 5,057 $13,623 $7,294 ROTAMIX+ROFA $4,858,000 3,809 $19,760 **LNB+OFA+HERT** $2,961,000 3,713 -$2,168 SNCR + LNB + OFA $4,210,000 3,137 $4,188 ROFA $3,406,000 2,945 -$677 ROTAMIX + LNB $3,536,000 2,753 -$5,125 SNCR + LNB $4,520,000 2,561 $36,094 **LNB + OFA** $1,055,000 2,465 $165 LNB $897,000 1,505 -$17,781 ROTAMIX $4,311,000 1,313 $30,021 SNCR $1,429,000 1,217 $1,161 **COS** $314,000 257
SCR costs from APS taken from Table 14 of October 2010 TSD (most recent cost estimates) All other costs taken from Table 5 of TSD, costs dated August 2008 TPY reductions estimated by APS (see cap factor tab) taken from Table 7 of TSD Dominant Options are shown in Bold Face font, and were determined from the least cost envelope charts
* We also show incremental costs against the technology APS determined was BART for each unit ** EPA determined that controls relying on LNB or OFA (highlighted in grey) will not be effective on Unit 3 due to limitations in the boiler configuration, as discussed in the TSD (see p 19)assumes 90.8% capacity factor used by APS, 0.59 to 0.118 lb/MMBtu, heat rate = 2400 mmbtu/hr

EPA incremental cost average cost effectiveness Dominant Options

SCR to SNCR** SCR to LNB+OFA $12,650 $3,236 $5,398 $3,947 $1,275 $1,527 APS incremenal cost $797 SCR to SNCR** SCR to LNB+OFA $1,342 $4,826 $7,294 $1,157 $1,284 $1,765 $336 $428 $596 $3,283 $1,174 $1,222

Dominant Options are shown in Bold Face font, and were determined from the least cost envelope charts

** EPA determined that controls relying on LNB or OFA (highlighted in grey) will not be effective on Unit 3 due to limitations in the boiler configuration, as discussed in the TSD (see p 19)EPA Annual Cost $12,114,000 Table 15 of TSD EPA tons per year reduced 3,806 assumes 91.1% capacity factor used by APS (see cap factor tab), 0.64 to 0.128 lb/MMBtu, heat rate = 1863 mmbtu/hr

Unit 2 NOx Control Total Annual Cost tpy reduced APS incremental cost All options SCR to LNB* Dominant Options **SCR** $20,978,000 4,310 $17,821 $7,328 $17,821 **ROTAMIX+ROFA** $4,191,000 3,368 $18,333 $18,333 **LNB+OFA+HERT** $2,816,000 3,293 -$2,305 $1,567 SNCR + LNB + OFA $3,851,000 2,844 $6,007 ROFA $2,956,000 2,695 -$3,680 ROTAMIX + LNB $3,508,000 2,545 -$2,752 SNCR + LNB $3,918,000 2,396 $35,000 **LNB + OFA** $1,293,000 2,321 $496 $496 **LNB** $922,000 1,573 -$22,669 $478 ROTAMIX $4,277,000 1,425 $4,421 SNCR $3,941,000 1,349 $3,464 **COS** $314,000 302
SCR costs from APS taken from Table 14 of October 2010 TSD (most recent cost estimates) All other costs taken from Table 5 of TSD, costs dated August 2008 TPY taken from Table 7, except for tpy values for LNB+OFA and LNB which were mistakenly reported in the TSD, the corrected values above are based from Table 5-2 of B&V report Dominant Options are shown in Bold Face font, and were determined from the least cost envelope charts
* We also show incremental costs against the technology APS determined was BART for each unit ** EPA determined that controls relying on LNB or OFA (highlighted in grey) will not be effective on Unit 2 due to limitations in the boiler configuration, as discussed in the TSD (see p 19)assumes 91.1% capacity factor used by APS (see cap factor tab), 0.64 to 0.128 lb/MMBtu, heat rate = 1863 mmbtu/hr

EPA incremental cost average cost effectiveness SCR to SNCR** SCR to LNB $3,326 $5,012 $4,867 $1,244 APS incremenal cost $855 SCR to SNCR** SCR to LNB $1,354 $5,754 $7,328 $1,097 $1,378 $1,635 $557 $586 $3,001 $2,921 $1,040

TPY taken from Table 7, except for tpy values for LNB+OFA and LNB which were mistakenly reported in the TSD, the corrected values above are based from Table 5-2 of B&V report

** EPA determined that controls relying on LNB or OFA (highlighted in grey) will not be effective on Unit 2 due to limitations in the boiler configuration, as discussed in the TSD (see p 19)EPA Annual Cost $11,475,000 Table 15 of TSD EPA tons per year reduced 4,578 assumes 89.9% capacity factor used by APS (see cap factor tab), 0.78 to 0.156 lb/MMBtu, heat rate = 1863 mmbtu/hr

Unit 1 NOx Control Total Annual Cost tpy reduced All Options SCR to LNB* Dominant Options **SCR** $19,334,000 5,134 $18,518 $7,178 $18,518 **ROTAMIX+ROFA** $4,223,000 4,318 $19,274 $19,274 **LNB+OFA+HERT** $2,816,000 4,245 -$2,217 $1,608 SNCR + LNB + OFA $3,785,000 3,808 $5,678 ROFA $2,956,000 3,662 -$3,807 ROTAMIX + LNB $3,508,000 3,517 -$2,336 SNCR + LNB $3,849,000 3,371 $35,014 **LNB + OFA** $1,293,000 3,298 $509 $509 **LNB** $922,000 2,569 -$3,543 $288 ROTAMIX $4,277,000 1,622 #DIV/0! SNCR $4,314,000 1,622 $3,431 **COS** $314,000 456
SCR costs from APS taken from Table 14 of October 2010 TSD (most recent cost estimates) All other costs taken from Table 5 of TSD, costs dated August 2008 TPY reductions estimated by APS taken from Table 7 of TSD Dominant Options are shown in Bold Face font, and were determined from the least cost envelope charts
* We also show incremental costs against the option APS determined was BART for each unit. APS calculated incremental cost in its comment letters by comparison with combustion controls ** EPA determined that controls relying on LNB or OFA (highlighted in grey) will not be effective on Unit 1 due to limitations in the boiler configuration, as discussed in the TSD (see p 19) APS incremental costassumes 89.9% capacity factor used by APS (see cap factor tab), 0.78 to 0.156 lb/MMBtu, heat rate = 1863 mmbtu/hr

EPA incremental cost average cost effectiveness SCR to SNCR** SCR to LNB

$2,423 $5,254 $3,766 $978 APS incremenal cost $663 SCR to SNCR** SCR to LNB $994

$4,277 $7,178 $807 $997 $1,142 $392 $359 $2,637 $2,660 $689

* We also show incremental costs against the option APS determined was BART for each unit. APS calculated incremental cost in its comment letters by comparison with combustion controls ** EPA determined that controls relying on LNB or OFA (highlighted in grey) will not be effective on Unit 1 due to limitations in the boiler configuration, as discussed in the TSD (see p 19)$10,000,000 $15,000,000 $20,000,000 $25,000,000**T o** **t a** **l A** **n n** **u a** **l C** **o s** **t o** **f C** **o n** **t r** **o l** **s** 

## Incremental **Cost of NOx Controls on**  **Unit 1 at Four Corners Power Plant**  **based on APS Cost Estimates**

Dominant Controls on Least

- Cost Envelope: (COS, LNB, LNB+OFA, LNB+OFA+HERT , ROTAMIX+ROFA, SCR)

$0 $5,000,000

0 1,000 2,000 3,000 4,000 5,000 6,000
**tons per year NOx reduced** Inferior Controls: (ROTAMIX, SNCR+LNB, ROTAMIX+LNB, ROFA, SNCR+LNB+OFA)$10,000,000 $15,000,000 $20,000,000 $25,000,000**T o** **t a** **l A** **n n** **u a** **l C** **o s** **t o** **f C** **o n** **t r** **o l** **s** 

## Incremental **Cost of NOx Controls on**  **Unit 2 at Four Corners Power Plant**  **based on APS Cost Estimates**

Dominant Controls on Least

- Cost Envelope: (COS, LNB, LNB+OFA, LNB+OFA+HERT , ROTAMIX+ROFA, SCR)

$0 $5,000,000

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000
**tons per year NOx reduced** Inferior Controls: (ROTAMIX, SNCR+LNB, ROTAMIX+LNB, ROFA, SNCR+LNB+OFA)$10,000,000 $15,000,000 $20,000,000 $25,000,000**T o** **t a** **l A** **n n** **u a** **l C** **o s** **t o** **f C** **o n** **t r** **o l** **s** 

## Incremental **Cost of NOx Controls on**  **Unit 3 at Four Corners Power Plant**  **based on APS Cost Estimates**

Dominant Controls on Least

- Cost Envelope: (COS, LNB+OFA, LNB+OFA+HERT , SCR)

$0 $5,000,000

0 1,000 2,000 3,000 4,000 5,000 6,000
**tons per year NOx reduced** Inferior Controls: (ROTAMIX, LNB, SNCR+LNB, ROTAMIX+LNB, ROFA, SNCR+LNB+OFA, ROTAMIX+ROFA)$20,000,000 $25,000,000 $30,000,000 $35,000,000 $40,000,000 $45,000,000 $50,000,000**T o** **t a** **l A** **n n** **u a** **l C** **o s** **t o** **f C** **o n** **t r** **o l** **s** 

## Incremental **Cost of NOx Controls on**  **Unit 4 at Four Corners Power Plant**  **based on APS Cost Estimates**

Dominant Controls on Least

- Cost Envelope:

$0 $5,000,000 $10,000,000 $15,000,000

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000
**tons per year NOx reduced**

Dominant Controls on Least

- Cost Envelope: (COS, LNB+OFA, SNCR+LNB+OFA, SCR) Inferior Controls (LNB, SNCR, SNCR+LNB)$20,000,000 $25,000,000 $30,000,000 $35,000,000 $40,000,000 $45,000,000**T o** **t a** **l A** **n n** **u a** **l C** **o s** **t o** **f C** **o n** **t r** **o l** **s** 

## Incremental **Cost of NOx Controls on**  **Unit 5 at Four Corners Power Plant**  **based on APS Cost Estimates**

Dominant Controls on Least

- Cost Envelope: (COS, LNB+OFA, SNCR+LNB+OFA, SCR)

$0 $5,000,000 $10,000,000 $15,000,000

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000
**tons per year NOx reduced**

(COS, LNB+OFA, SNCR+LNB+OFA, SCR)

Inferior Controls (LNB, SNCR, SNCR+LNB)Calculation of capacity factors

From information in 2007 B&V report

Baseline Post-control TPY reduced Max Heat Rate Max Hours ton to lb conv Unit 1 0.78 0.08 5134 1863 8760 2000 Unit 2 0.64 0.06 4310 1863 8760 2000 Unit 3 0.59 0.06 5057 2400 8760 2000 Unit 4 0.49 0.06 11445 7806 8760 2000 Unit 5 0.49 0.06 11445 7806 8760 2000Capacity Factor

89.9% 91.1% 90.8% 77.8% 77.8%