2|February 23, 2010 ICAPCD RULE 400.2 APPENDIX C

There is not a federal policy that establishes maximum cost effectiveness values for NOx 

RACT. The San Joaquin Valley APCD uses a BARCT threshold of $9,700.00 (California 

Air Resources Board (CARB), Report to the Legislature, Implications of Future Oxides of 

Nitrogen Controls from Seasonal Sources in the San Joaquin Valley, January 2002, Table

9, Comparison of BARCT Cost Effectiveness Thresholds). Therefore, for the purpose of 

this evaluation, the ICAPCD will use a RACT cost effectiveness value of $8,000-

$10,000/ton of NOx. The cost of control equipment is highly dependent on the size of the 

unit and the type of control selected. According to the APCD survey, the majority of the 

boilers that will be impacted by Rule 400.2 are in the range of 50-200 MMBtu/hour. 

Therefore, the cost effectiveness evaluation was conducted for several size boilers ranging 

from 50 to 200 MMBtu/hour and capacity factors ranging from 10% to 75%. To estimate 

cost effectiveness, ICAPCD staff obtained capital cost estimates of a low NOx burner with 

flue gas recirculation system from Jeff Welton and Pete Santner, R.F. MacDonald 

Company. According to Pete Santner (e-mail message on December 3, 2009), boilers 

with capacity 50-200 MMBtu/hr would need to be retrofit with a combination of low-NOx 

burner and flue gas recirculation system in order to reduce NOx emissions to a minimum 

of 30 ppmv for gaseous fuel-fired units.

The total initial cost (capital cost and installation) for a low NOx burner and flue gas 

recirculation system for boilers 50 to 200 MMBtu/hr ranges from $401,000 to $732,000. 

The average cost effectiveness ranges from approximately $6,470 to $48,580 per ton of 

NOx reduced. The high end of the cost effectiveness range is due to low annual heat input 

of boilers. This evaluation indicates that it is cost effective to retrofit boilers to low-NOx 

burner and flue gas recirculation but only for those units operating under an annual 

capacity factor above 30%. Therefore, Rule 400.2 will establish an alternative NOx 

emission limit of 70 ppmv for those existing emission units with an annual capacity factor 

of 30% or less. The annual capacity factor is the ratio of the amount of fuel burned by an 

emission unit in a calendar year to the amount it could have burned if it had operated all 

year around; in other words, it represents 30% of the potential annual fuel consumption for 

the emission unit. 

The ICAPCD staff conducted a survey of the permit database to identify the number of 

boilers which will need to be retrofitted to comply with the new RACT requirements. 

Approximately 13 units rated 50 million Btu per hour or greater are operated at three of 

Imperial County’s major source facilities and will be affected by the requirements of Rule 

400.2. The ICAPCD survey indicates that one of the boilers (Unit 4) operated by 

Imperial Irrigation District at the El Centro Generating Facility and three of the natural 

gas boilers operated by Spreckels Sugar Company would be out of compliance with the 

30 ppmv emission limit with current NOx control technology. Unit 4 is currently equipped 

with Selective Catalytic Reduction (SCR) and Spreckels Sugar Company has indicated 

that its natural gas boilers will be retrofitted with Flue Gas Recirculation technology. 

However, this type of NOx control technology would not be able to reduce NOx 

emissions to the 30 ppmv limit. Therefore, a 70 ppmv NOx limit would be feasible to 

achieve with the current and proposed technology for these units. The ICAPCD staff 

evaluated cost effectiveness for retrofitting the Spreckels Sugar boilers and the El Centro 
3|February 23, 2010 ICAPCD RULE 400.2 APPENDIX C

Generating Facility Unit 4 boiler to meet the 30 ppmv limit, a detailed cost effectiveness 

evaluation for these boilers is included in Section II.b of this report. This evaluation 

indicates that due to the seasonal nature of operation of the Spreckels Sugar natural gas 

boilers and El Centro Generating Unit 4 boiler, the cost for retrofitting these boilers is 

higher than the recommended cost effectiveness threshold. Therefore, these emission 

units will be restricted to 70 ppmv NOx and maximum annual capacity factor of 30%.

It is important to point out that any new boilers will need to comply with BACT 

requirements; therefore, these units will be required to install more efficient technology to 

reduce NOx emission, hence the capital and operational cost will be higher.

II. COST EFFECTIVENSS

A Low NOx with Flue Gas Recirculation System

The cost of retrofitting units to comply with the proposed rule varies with the size of the unit 

and the type of controls used. ICAPCD staff analyzed the cost effectiveness of Rule 400.2 

based on installing and operating of low-NOx burner system and flue gas recirculation 

because this is the control technology that will most likely be used by local industry to 

comply with this rule. The cost effectiveness evaluation was conducted for several sizes 

of units ranging from 50 to 200 MMBru/hour. 

The potential NOx emission reductions were evaluated using the following assumptions:

• Baseline emissions are 0.0848 lb/MMbtu (70ppmv @ 3% O2)

• Controlled emissions are 0.036 lb/MMbtu (30ppmv @ 3% O2)

• Operating schedule 24 hour/day; 365 days/year

• 0.10, 0.25, 0.30, 0.50 and 0.75 capacity factors

Table 1 provides a summary of NOx emissions reductions for boilers at different capacity

factors.

Table 1 Potential NOx Emissions Reductions

Unit Size 

MMBtu/hr

Capacity Factor Uncontrolled 

Emissions 

Tons/yr

Controlled 

Emissions 

Tons/yr

NOx Reductions 

Tons/year

50 0.10 1.86 0.79 1.07

50 0.25 4.64 1.97 2.67

50 0.30 5.57 2.36 3.31

50 0.50 9.29 3.94 5.35

50 0.75 13.93 5.91 8.02

100 0.10 3.71 1.58 2.13

100 0.25 9.29 3.94 5.35

100 0.30 11.14 4.73 6.41

100 0.50 18.57 7.88 10.69

100 0.75 27.86 11.84 16.02

150 0.10 5.57 2.37 3.2

150 0.25 13.93 5.91 8.02
4|February 23, 2010 ICAPCD RULE 400.2 APPENDIX C

150 0.30 16.71 7.10 9.61

150 0.50 27.86 11.83 16.03

150 0.75 41.79 17.74 24.05

200 0.10 7.43 3.15 4.28

200 0.25 18.57 7.88 10.69

200 0.30 22.28 9.46 12.82

200 0.50 37.14 15.77 21.37

200 0.75 55.71 23.65 32.06

To estimate cost effectiveness, ICAPCD staff obtained capital cost estimates of a low NOx 

burner with flue gas recirculation system from Jeff Welton and Pete Santner, R.F. 

MacDonald Company. In addition, to estimate cost for installation and operation of the 

boilers, ICAPCD staff used information provided by the CARB, Report to the Legislature, 

Implications of Future Oxides of Nitrogen Controls from Seasonal Sources in the San 

Joaquin Valley, January 2002. The method for calculating cost effectiveness on CARB’s 

evaluation assumes a 10% interest rate and useful life for the control equipment of 10 

years. Table 2 provides a summary of cost to control NOx emissions for different boiler 

capacities.

Table 2 Cost of NOx Control for Boilers

Boiler Capacity, 

MMBtu/hr

50 100 150 200

NOx emission limit, ppm 30 30 30 30

Capital cost, $ 336K 475K 525K 600K

Installation cost, $ 65K 96K 108K 132K

Total initial cost, $ 401K 571K 633K 732K

Capital cost amortization 

factor1

0.163 0.163 0.163 0.163

Annual repair and 

maintenance cost, $

5K 10K 15K 20K

Annual operation cost, $ 306 1222 2750 4888

Annual source test cost, $ 4K 4K 4K 4K

Total annual cost, $ 74.7K 108.3K 124.9K 148.2K

Table 3 indicates the cost effectiveness for boilers at various capacity factors that are 

subject to the 0.036 lb/MMBtu or 30 ppm standard.

Table 3 Cost Effectiveness for Boilers 50 to 200 MMBtu/hour

Unit Size 

(MMBtu/hr)

Capacity Factor

(%)

10 25 30 50 75

50 69.81K 27.98K 22.57K 13.96K 9.31K

100 50.84K 20.24K 16.90K 10.13K 6.76K

 

1 Uses a 10% interest rate and useful life data from the manufacturers survey, when available.
5|February 23, 2010 ICAPCD RULE 400.2 APPENDIX C

150 39.03K 15.57K 13.00K 7.79K 5.19K

200 34.63K 13.86K 11.56K 6.93K 4.62K

Average 48.58K 19.41K 16.00K 9.70K 6.47K

B Alternative NOx Emission Limit

Rule 400.2 established an alternative NOx emission limit of 70 ppmv for those existing 

emission units with an annual capacity factor of 30% or less. The annual capacity factor is 

the ratio of the amount of fuel burned by an emission unit in a calendar year to the amount 

it could have burned if it had operated all year around; in other words, it represents a 30% 

of the potential annual fuel consumption for the emission unit. This alternative emission 

threshold has been established for existing seasonal emission units for which installation 

of advanced control technology would not have a significant impact in reducing NOx 

emissions due to irregular operation of the emission unit.

Spreckels Sugar Company operates three boilers which are not equipped with any type of 

NOx controls. The three natural gas boilers were installed in 1977 and will have to comply 

with Rule 400.2 RACT requirements. The operation of these boilers is seasonal and 

therefore retrofitting of the boilers to comply with the 30 ppmv @ 3% O2 may not be cost 

effective. Spreckels Sugar Company has indicated that its natural gas boilers will be 

retrofitted with Flue Gas Recirculation technology to comply with the 70 ppmv @ 3% O2.

Table 5 Spreckels Sugar Company Cost Effectiveness Evaluation

Emission Unit Approximate

Unit Size 

(MMBtu/hr)

Annual Cost 

for Retrofitting 

at 30 ppm 

Cost per Ton of 

NOx Reductions 

Based on Potential 

Reductions 

Cost 

Effective 

(yes/no)

CE Boiler 200 148.2K 16.21K No

Union Boiler 150 124.9K 99.92K No

Auxiliary Boiler 100 108.3K 773.57K No

Table 4 Spreckels Sugar Company Potential NOx Reductions 70 ppm to 30 ppm 

(Year 2006-2008 Average Natural Gas Consumption)

Emission 

Unit

Unit Size 

(MMBtu/hr)

Average

Natural Gas 

Used 

MMBtu/year

NOx Emissions at 

70 ppm 3% O2

(0.0848 lb/MMBtu)

(tpy)

NOx Emissions 

at 30 ppm 3% O2

(0.036 lb/MMBtu)

(tpy)

Potential NOx 

Reductions 

(tpy)

CE Boiler 202 374,448 15.88 6.74 9.14

Union 

Boiler 

144 51,448 2.18 0.93 1.25

Auxiliary 

Boiler 

95 5,938 0.25 0.11 0.14
6|February 23, 2010 ICAPCD RULE 400.2 APPENDIX C

Imperial Irrigation District operates one boiler which is currently equipped with selective 

catalytic reduction system for NOx control (SCR system). This unit was installed in 1968 

without any NOx controls. This boiler has a heat input capacity of 829.8 MMBtu/hr. In 

2000 the boiler was retrofitted with the SCR system to meet the 140 pounds per hour 

limit of the ICAPCD Rule 400. The operation of this boiler is seasonal by nature and 

therefore further retrofitting of this boiler to comply with the 30 ppmv @ 3% O2 may not be 

cost effective. Imperial Irrigation District has indicated that it will adjust the operation of its 

natural gas boiler to comply with the 70 ppmv @ 3% O2. The ICAPCD Cost 

Effectiveness evaluation does not analyze cost effectiveness for Imperial Irrigation District 

size boiler. The facility provided the estimated capital and installation cost for retrofitting of 

Unit 4 Boiler to meet the 30 ppmv limit of Rule 400.2. The ICAPCD staff estimated the 

cost effectiveness for retrofitting the Unit 4 boiler from 70 ppmv to 30 ppmv. Table 6 

presents cost effectiveness evaluation for retrofitting the Unit 4 boiler to 30 ppmv. This 

evaluation indicates that based on the $8,000-$10,000 threshold established by the 

ICAPCD for RACT determination, it is not cost effective to require unit 4 to retrofit to 30 

ppmv but rather limit operation of this unit at 70 ppmv and 30% capacity factor. 

Table 6 Cost of NOx Control for Boilers

Unit 4 Boiler 829.8 MMBtu/hr

NOx emission limit, ppm 30

Capital and Installation cost, $ 4,250K

Capital cost amortization 

factor2

0.163

Equivalent annual capital cost 

of controls3

692.75K

, $

Annual repair and 

maintenance cost, $

5K

Annual operation cost, $ 40K

Annual source test cost, $ 4K

Total annual cost, $ 741.75K

Average annual emissions 

reduction, TPY

40.47

Cost Effectiveness, $/Ton 18.33K

Cost Effective? No

 

2 Uses a 10% interest rate and useful life data from the manufacturers survey, when available.

3 Uses average capital and installation costs.