2|January 26, 2010 ICAPCD RULE 400.1 APPENDIX A

was installed with a Selective Catalytic Reduction (SCR) and is able to comply with a NOx 

emission limit of 9 ppmv when operating with natural gas and 13 ppmv when operating 

under diesel fuel. In addition, in 2008, the IID, Niland Generation Station, installed two 

stationary gas turbines. These units are equipped with SCR and are able to comply with 

a NOx emission limit of 2.5 ppmv. These turbines are only authorized to burn natural gas. 

Without the installation of additional technology, these emission units are currently in 

compliance with Rule 400.1 emission limits. Therefore, no substantial change in the 

emissions inventory for these facilities due to implementation of this rule is anticipated. 

The IID, Brawley Generation Station, operates two turbines that were installed in 1962 

and do not have installed NOx emission control equipment. These units will be exempted 

from compliance with Rule 400.1 NOx emissions limits by restricting operation to no more 

than 400 hours per calendar year. 

The IID, Rockwood Generation Station, operates two turbines that were installed in 1979 

and have installed water injection for NOx emission control. These units are able to 

comply with Rule 400.1 NOx emissions limits of 42 ppmv for natural gas and 65 ppmv for 

diesel fuel. An analysis will be conducted in this Appendix to evaluate cost effectiveness 

for installation of SCR equipment to further reduce NOx emissions to 9 ppmv for natural 

gas and 15 ppmv for diesel fuel on these units. 

There is no federal policy that establishes maximum cost effectiveness values for NOx 

RACT. The San Joaquin Valley Air Pollution Control District (SJVAPCD) uses a BARCT 

threshold of $9,700.00. (California Air Resources Board, 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 APCD 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. 

The total initial cost (capital cost and installation) for retrofitting the Rockwood turbines 

with a SCR system is approximately $4,400,000. In addition, the estimated annual 

operating cost for each turbine is $276,803. Therefore, the estimated cost effectiveness 

for Unit 1 when burning natural gas is $61,731 per ton of NOx reduced, while the 

estimated cost effectiveness for both units when burning diesel fuel is $44,839 per ton of 

NOx reduced. This evaluation indicates that the cost effectiveness to retrofit the 

Rockwood turbines with a SCR system is way higher than the recommended RACT cost 

effectiveness value of $8,000-$10,000/ton of NOx. Therefore, these units will not be 

required to install more efficient technology to reduce NOx emission.

II. COST EFFECTIVENESS EVALUATION

A. Selective Catalytic Reduction System

The cost effectiveness analysis contained in this report was based upon cost estimates 

and methodology contained in the staff report for the SJVAPCD Rule 4703, Stationary 

Gas Turbines, Appendix C, as proposed August, 16, 2007.
3|January 26, 2010 ICAPCD RULE 400.1 APPENDIX A

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 

400.1 which was based on the installation and operation of a SCR system on Rockwood 

Unit 1 and Unit 2 gas turbines. The Unit 1 and Unit 2 turbines currently have installed 

water injection as NOx controls and both turbines are restricted to operate a maximum of 

1000 hours per calendar year (Authority to Construct and Title V permit conditions). Unit 

1 has the capability to burn natural gas and diesel and Unit 2 has the capability to burn 

diesel only. Both turbines are identical with a 22MW capacity, 308.6 MMBtu/hr when 

burning natural gas and 280.5 MMBtu/hr when burning diesel fuel.

1. Estimated Annual NOx Emissions Reduction – Equations

The estimated Current and Potential Annual NOx Emissions were calculated using the 

following equation and assumptions:

NOx = LF x MMBtu/hr x HR x EF / 2,000 lb/ton

Where:

NOx = Current Annual NOx Emissions or Potential Annual NOx 

Emissions

LF = turbine load factor

MMBtu/hr = heat input rating

HR = annual hours of operation

EF = NOx emission factor in pounds per MMBtu

Estimated Annual NOx Emissions Reduction = Current Annual NOx Emissions –

Potential Annual NOx Emissions

a) Unit 1 Estimated Potential Annual NOx Emissions when burning Natural Gas.

A. Current Annual NOx Emissions – 42 ppm

Unit 1- Parameters:

LF = 0.75 capacity factor

MMBtu/hr = 308.6 MMBtu/hr – Natural Gas

HR = 1,000 hour of operation per year

EF = NOx emission Factor in ppm x 0.00366 lb/MMBtu per ppm NOx

NOx = 0.75 x 308.6 MMBtu/hr x 1,000 hr x (42 ppm x 0.0036 lb/MMBtu/ppm) / 2000 lb/ton

NOx = 17.50 tons

B. Potential Annual NOx Emissions – 9 ppm

NOx = 0.75 x 308.6 MMBtu/hr x 1,000 hr x (9 ppm x 0.0036 lb/MMBtu/ppm) / 2000 lb/ton
4|January 26, 2010 ICAPCD RULE 400.1 APPENDIX A

NOx = 3.75 tons

C. Estimated Annual NOx Emissions Reductions

The estimated Annual NOx Emissions Reduction was calculated using the following 

equation:

NOx Emissions Reduction = Current Annual NOx Emissions – Potential Annual NOx 

Emissions.

NOx Emissions Reduction = 17.50 – 3.75 = 13.75 tons

b) Unit 1 and Unit 2 Estimated Potential Annual NOx Emissions when burning Diesel.

A. Current Annual NOx Emissions – 65 ppm

Units 1 and 2 - Parameters:

LF = 0.75 capacity factor

MMBtu/hr = 280.5 MMBtu/hr – Diesel

HR = 1,000 hour of operation per year

EF = NOx emission Factor in ppm x 0.00366 lb/MMBtu per ppm NOx

NOx = 0.75 x 280.5 MMBtu/hr x 1,000 hr x (65 ppm x 0.0036 lb/MMBtu/ppm) / 2000 lb/ton

NOx = 24.61 tons

B. Potential Annual NOx Emissions – 15 ppm

NOx = 0.75 x 280.5 MMBtu/hr x 1,000 hr x (15 ppm x 0.0036 lb/MMBtu/ppm) / 2000 lb/ton

NOx = 5.68 tons

C. Estimated Annual NOx Emissions Reductions

The estimated Annual NOx Emissions Reduction was calculated using the following 

equation:

NOx Emissions Reduction = Current Annual NOx Emissions – Potential Annual NOx 

Emissions.

NOx Emissions Reduction = 24.61 – 5.68 = 18.93 tons
5|January 26, 2010 ICAPCD RULE 400.1 APPENDIX A

2. Calculation of SCR Annual Costs

As stated earlier, to estimate cost effectiveness, ICAPCD staff used cost information 

contained in the staff report for the SJVAPCD Rule 4703, Stationary Gas Turbines, 

Appendix C. The ICAPCD staff estimated the cost of retrofitting for the installation and 

operation of a SCR system of the Rockwood turbines. As per SJVAPCD report, a low 

cost estimate of $200/KW for retrofitting was assumed. This method also assumes a 10% 

interest rate and a useful life for the control equipment of 15 years. Table 2 provides a 

summary of cost to control NOx emissions, including direct capital cost and direct and 

indirect costs for operation.

Table 2. SCR Annual Cost

ITEM SOURCE COST

Turbine Rating 22 MW

SCR Cost/KW- Retrofitting $200.00/KW

Operating Hours 1000

Direct Capital Cost

Total Capital Investment

(TCI)

$4,400,000

Direct Annual Cost

Operating Costs

Operator 0.5 hr/shift, $25.00/hr OAQPS $16,859

Supervisor 15% of Operator $ 2,859

Maintenance Cost

Labor 0.5 hr/shift, $25.00/hr OAQPS $16,859

Material 100% of labor cost OAQPS $16,859

Utility Cost

Electricity Cost Variable $5,747

Cat. Replacement MHIA $5,621

Cat. Disposal OAQPS $ 211 

Ammonia Variable $1,008

NH3 Inject Skid MHIA $2,916

Indirect Annual Cost

Overhead 60% of O and M OAQPS $31,864

Administrative 0.02xTCI OAQPS $88,000

Insurance 0.01xTCI OAQPS $44,000

Property Tax 0.01xTCI OAQPS $44,000

Total Annual Costs $276,803
6|January 26, 2010 ICAPCD RULE 400.1 APPENDIX A

Table 3 summarizes the results of the cost effectiveness calculations for retrofitting of the 

Rockwood turbines. Cost effectiveness. The analysis includes two scenarios, the first 

analyzes cost effectiveness for Unit 1 while operating under natural gas, and a second 

includes an analysis for Units 1 and 2 while operating under diesel fuel.

Table 3 Cost Effectiveness for Retrofitting Rockwood Turbines

Item Unit 1 

Natural Gas

Units 1 and 2 

Diesel

MW 22 22

MMBtu/hr 308.6 280.5

NOx Reductions 

(tons/year)

13.75 18.93

SCR Cost/MW $200 $200

Cost Installed Control 

Equipment

$4,400,000 $4,400,000

Annualized 

Equipment Cost

$572,000 $572,000

Annual Operation 

Cost 

$276,803 $276,803

Total Annual Cost $848,803 $848,803

Cost Effectiveness 

($/ton) 

$61,731 $44,839