SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 1 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

APPENDIX B 

Emission Reduction Analysis 

For Revised Proposed Amendments to Rule 4702 

August 18, 2011 
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 2 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

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SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 3 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

EMISSION REDUCTION ANALYSIS FOR 

REVISED PROPOSED RULE 4702 (INTERNAL COMBUSTION ENGINES) 

I. SUMMARY 

The purpose of this rule project is to obtain as much reductions nitrogen oxides (NOx) 

emission from the source category as expeditiously practical, technologically feasible, 

and economically reasonable, as determined by the District’s Governing Board. The 

District committed to amending Rule 4702 as part of both the District’s 2007 Ozone Plan 

and the 2008 PM2.5 Plan; however, neither plan committed the District to a specific 

amount of emission reductions. This appendix details the calculations and assumptions 

used to estimate the NOx emission reductions associated with the proposed 

amendments to Rule 4702. Emission reductions were estimated using permit 

conditions of the individual engine and the proposed rule’s emission limits. 

Previous drafts of the rule during this rule-amending project included the potential for 

carbon monoxide (CO) and volatile organic compounds (VOC) reductions; however, no 

change in CO or VOC emission limits are included in the revised proposed rule. There 

are no VOC or CO emission reductions associated with the proposed amendments for 

this rule project. 

In order to determine the emission reductions associated with the changes, District staff 

queried the District Permit Services Database for all engines, and then manually sorted 

the engines into one of three categories: emergency standby, rich-burn, and lean-burn. 

No analysis was done for emergency standby engines because the proposed rule 

amendments do not affect this type of engine. Of the remaining engines, District staff 

determined that out of 326 rich-burn engines, only 160 engines would be required to 

reduce their NOx emissions. For lean-burn engines, District staff found a total of 97 

lean-burn engines, of which, 62 have permit limits higher than the proposed rule limits. 

District staff estimates that the proposed changes in the rule limits for non-AO sparkignited engines would lead to approximately 1.4 tons per day (tpd) of NOx emission 

reductions. However, in the strictest sense, these emission reductions cannot be 

directly credited to the District’s attainment plans for State Implementation Plan (SIP) 

purposes because at least a portion of them will come as part of the fee payment 

program. Emission reductions in a fee payment program cannot be credited to the 

District until they are actually achieved. Although District staff expects that the Rule 

4702 program will generate more emission reductions than what has been calculated, 

this rule project will take no credits for SIP purposes at this time. Although not taking 

credit for the emission reductions for SIP purposes, the NOx emission reductions are 

used in determining the cost effectiveness of the proposed rule amendments. A 

summary of the emission reduction analysis results is shown in Table 1 and details of 

the calculations are explained later in this appendix. 
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 4 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

Table 1 – Summary of Estimated NOx Reductions Used for Cost Effectiveness 

Calculations 

Engine Type 

Total 

Permitted 

Engines 

Number 

Affected 

Engines 

Total Rated 

Power (bhp)

Estimated 

NOx 

Reductions 

(tpy) 

Estimated 

NOx 

Reductions 

(tpd) 

Rich-Burn 326 160 80,738 131.5 0.360

Lean-Burn 97 62 123,886 390.9 1.071

Totals 423 222 204,624 522.4 1.431

II. BACKGROUND 

There are two types of non-AO spark-ignited engines that would be affected by the 

proposed rule changes: rich-burn and lean-burn engines. District staff estimates that 

there are 326 rich-burn engines and 97 lean-burn non-emergency-standby engines that 

are currently under permit with the District and are subject to Rule 4702. Over 75% of 

the 222 engines affected by the proposed rule amendments are used in the oil fields. 

Effective NOx emission control equipment for rich-burn engines is non-selective 

catalytic reduction systems (NSCR). For lean-burn engines, the most common NOx 

emission control equipment is selective catalytic reduction (SCR). Both control systems 

require catalysts to convert NOx to nitrogen gas. The NSCR tends to be less expensive 

to install and operate than a SCR system, but requires high temperature at the engine’s 

outlet in order to be effective. Because of this temperature requirement, NSCR is 

usually installed on rich-burn engines and SCR is confined to lean-burn engines. 

III. EMISSION REDUCTION ANALYSIS

It is the District’s experience that, when an emission limit is reduced, a small percentage 

of operators will choose to replace their internal combustion (IC) engines with electric 

motors rather than retrofit with an emission control system. Based on past experience 

with engine rule amendments, staff estimate that there would be two to three engines 

replaced by electric motors. It would be speculative, at best, to determine which 

engines would electrified, therefore the following the emission reduction analysis does 

not include any estimate of NOx reductions for electrification. 

A. Affected Engines 

District staff queried the Permit Services Permits Database for non-AO spark-ignited 

engines. The returned records were then manually sorted into one of three groups: 

emergency standby/dormant engines; rich-burn engines; and lean-burn engines. The 

emergency standby engines and dormant engines were removed from the analysis. 

The information about the remaining engines’ facility and the permit information were 
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 5 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

scrutinized to estimate which engines would fit the limited-use definition and which 

engines would fit the cyclic-loaded field gas fueled definition and the waste gas fueled 

definitions. These engines were analyzed separate from rich-burn and lean-burn 

engines. 

B. NOx Emission Reduction Calculations 

After the initial sorting, District staff read each permit to determine the engine’s current 

NOx emission limit. The emission limit was then converted from ppmvd to gram per 

brake horsepower-hour (g/hp-hr) The difference between the permit limit and the 

proposed rule limit was then multiplied by a 65% load factor and by assuming that the 

engine operated 6,570 hours annually (75% of the time). An example calculation for an 

800 hp rich-burn engine is shown below. Note that 0.359 grams per brake horsepowerhour (g/bhp-hr) is equivalent to 25 ppmvd and 0.153 g/bhp-hr is equivalent to 11 ppmvd. 

Emission Reduction = (0.359 - 0.153 g NOx/bhp-hr) X (800 bhp) X (6570 hr/yr) X (0.65 

load factor) X (1 lb/453.6 g) x (1 ton/2,000 lb) 

 = 0.78 tons NOx/year 

The individual engine emission reductions were added together to get the total emission 

reductions for the engine type (rich-burn or lean-burn) and for the rule project overall. 

Results of the calculations are shown in Table 1 above. 

Individual equipment descriptions were scrutinized to determine which engines would 

fall into the variable load category. NOx emission reductions associated with lean burn 

engines used for gas compression were calculated by assuming that the uncontrolled 

emission factor is 1125 ppmvd corrected to 15% oxygen then applying the 93% 

reduction to the uncontrolled emissions. Using this methodology, the emissions from 

variable load engines is 79 ppmv at 15% oxygen. 

Details of the rich-burn estimations are shown in Table 2 and details of the lean-burn 

engine estimations are shown in Table 3. Table 2 and Table 3 are located at the end of 

this appendix. 
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 6 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

Special Engine Categories 

Some engines will not see a change in the NOx emission limit as a result of this ruleamending project, based on technological and cost effectiveness considerations. The 

three groups that will not see a change in NOx emission limits are waste-gas fueled, 

cyclic-loaded field gas-fueled and limited use engines. 

Due to the heat content variability of waste gas, NOx control can be problematic for 

engines fired on waste gas, therefore, District staff is proposing that there be no change 

to the NOx emission concentration limit for waste gas fueled engines. No emission 

reductions are estimated for this group of engines. 

Cyclic-loaded field gas-fueled engines have retained the current emission concentration 

limit due to technology constraints. Because the exhaust temperature fluctuates, the 

total exhaust heat from these engines is not high enough for a NOx emission control 

system to work effectively. Therefore, the proposed rule would not change the NOx 

emission concentration limit from its present limit. No emission reductions are 

estimated for this group of engines. 

District staff propose not lowering the emission concentration limit for non-AO, nonemergency, and limited-use engines. The cost effectiveness for limited-use engines 

(engines operating less than 4,000 hours annually) is considered too high. Details of 

the cost effectiveness calculation are shown in Appendix C of this staff report. No leanburn engines and only eleven rich-burn engines are expected to be limited-use engines. 

If the emission limit for these engines were lowered to 11 ppmvd, only 1.4 tons per year 

(tpy) or 0.004 tpd of NOx emission reductions will be achieved. 

IV. GREENHOUSE GAS (GHG) EMISSIONS FOR CEQA PURPOSES

It is assumed that rich burn engines affected by this rule amendment already are 

equipped with NSCR. As such, there will be no GHG increase attributed to the richburn engine category at this time because there is no change to the control technology. 

For purposes of assessing environmental impact, District staff assumes that operators 

of the lean-burn engines affected by the proposed rule amendments do not currently 

have SCR units, but will install SCR units as the control technology of choice In order to 

meet the rule’s stringent NOx emission limits. SCR control technology can reduce the 

fuel efficiency of an engine by as much as 5%, meaning that 5% more fuel must be 

burned in order to have the same power output. Utilizing 5% as a conservatively high 

assumption for an engine's power penalty due to the use of an SCR system, and 

conservatively applying that power loss to the total rated horsepower of all engines 

affected by the rule changes (a total of 123,886 bhp), there is a 6,194 bhp increase. 
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 7 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

A carbon dioxide equivalents (CO2e) emission factor of 385 g CO2e/bhp-hr was 

multiplied by the 6,194 hp of increased fuel usage, a 0.75 load factor; 8500 hours/year 

and some conversion factors to get an annual increase of 1,520 metric tons CO2e. 

Based on the US Department of Energy’s “Buying an Energy-Efficient Electric Motor” 

Motor Challenge Fact Sheet, figures 1 and 2, an electric motor efficiency (mechanical 

power output divided by electric power input) of 90% or greater is expected for electric 

engines rated at 50 HP or greater and operating at 40% or greater load. Based on this 

document, the CO2e emissions from electric motors are 29% less than for natural gas 

fired engines. The 1,520 ton per year CO2e increase could be offset by 2.2 engines 

([CO2e increase/(1-0.29)]/average hp of affected engines). Electrification of two to 

three engines is a plausible compliance outcome. Thus, the District concludes that 

implementation of the proposed revisions would have a less than cumulative significant 

impact on global climate change. 

V. CONCLUSION

District staff estimated emission reductions from a subset of engines subject to Rule 

4702. Using information from each permit, District staff calculated emission reductions 

from each affected engine. Emission reductions from individual engines were added 

together to get the total estimated emission reductions from all affected engines. 

District staff estimates that the proposed amendments to Rule 4702 will reduce NOx 

emissions by about 1.4 tpd. However, since operators have the option to pay a fee in 

place of complying with the emission limits, no SIP credit can be taken for the emission 

reductions calculated as part of the rule project. Emission reductions associated with 

fee payment programs allow the District to take credit for the emission reductions at the 

time the fee is paid rather than when the rule is submitted for inclusion in the SIP. 

Results of the emission reduction calculations are used for estimating cost 

effectiveness. The summarized emission reductions estimates are shown in Table 1 at 

the beginning of this appendix. 
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 8 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

Table 2 — Estimated Rich-Burn NOx Reductions for Calculating Cost Effectiveness 

Power 

Output (bhp) 

Current PTO NOx 

Limit (ppmv) 

Proposed NOx 

Limit (g/bhp-hr) 

NOx Emission 

Reduction (tons/yr) SIC 

80 25 11 0.08 1311

95 25 11 0.09 1311

95 50 11 0.26 1311

104 25 11 0.10 1311

115 20 11 0.07 1311

120 25 11 0.12 2911

120 25 11 0.12 2911

150 25 11 0.15 2911

151 25 11 0.15 1311

157 25 11 0.15 1311

157 25 11 0.15 1311

157 25 11 0.15 1311

157 25 11 0.15 1311

162 50 11 0.44 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 9 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

Table 2 — Estimated Rich-Burn NOx Reductions for Calculating Cost Effectiveness (cont’d) 

Power 

Output (bhp) 

Current PTO NOx 

Limit (ppmv) 

Proposed NOx 

Limit (g/bhp-hr) 

NOx Emission 

Reduction (tons/yr) SIC 

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

162 25 11 0.16 1311

163 19 11 0.09 1311

165 25 11 0.16 2911

165 25 11 0.16 2911

165 25 11 0.16 2911

180 25 11 0.18 2911

180 25 11 0.18 2911

180 25 11 0.18 2911

180 25 11 0.18 1311

193 114 11 1.40 1389

195 25 11 0.19 1311

195 25 11 0.19 1311

195 25 11 0.19 1311

195 50 11 0.53 1311

195 25 11 0.19 1311

195 25 11 0.19 1311

195 25 11 0.19 1311

195 25 11 0.19 1311

195 25 11 0.19 1311

195 25 11 0.19 1311

195 25 11 0.19 1311

195 13 11 0.03 1311

195 25 11 0.19 1311

197 25 11 0.19 2099

199 25 11 0.20 1311

200 25 11 0.20 1311

208 50 11 0.57 1311

208 25 11 0.20 1311

208 25 11 0.20 1311

208 90 11 1.15 1311

208 25 11 0.20 1311

208 25 11 0.20 1311

220 50 11 0.60 1311

316 25 11 0.31 1311

316 25 11 0.31 1311

316 25 11 0.31 1311
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 10 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

Table 2 — Estimated Rich-Burn NOx Reductions for Calculating Cost Effectiveness (cont’d) 

Power 

Output (bhp) 

Current PTO NOx 

Limit (ppmv) 

Proposed NOx 

Limit (g/bhp-hr) 

NOx Emission 

Reduction (tons/yr) SIC 

316 25 11 0.31 1311

325 25 11 0.32 1311

330 25 11 0.32 1311

365 25 11 0.36 1311

370 25 11 0.36 1311

370 25 11 0.36 1311

400 25 11 0.39 1311

400 25 11 0.39 1311

490 59 11 1.65 1311

490 59 11 1.65 1311

490 59 11 1.65 1311

490 59 11 1.65 1311

498 25 11 0.49 1311

498 25 11 0.49 1311

500 25 11 0.49 1311

500 25 11 0.49 1311

525 25 11 0.52 1311

525 25 11 0.52 1311

525 25 11 0.52 1311

525 25 11 0.52 1311

525 25 11 0.52 1311

525 25 11 0.52 1311

600 25 11 0.59 1311

615 25 11 0.60 1311

625 25 11 0.61 1311

640 25 11 0.63 1311

650 59 11 2.19 1311

650 59 11 2.19 1311

650 59 11 2.19 1311

650 59 11 2.19 1311

660 59 11 2.22 1311

765 25 11 0.75 1311

765 25 11 0.75 1311

765 25 11 0.75 1311

767 25 11 0.75 1311

767 25 11 0.75 1311

767 25 11 0.75 1311

800 25 11 0.79 1311

800 25 11 0.79 1311

880 25 11 0.86 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 11 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

Table 2 — Estimated Rich-Burn NOx Reductions for Calculating Cost Effectiveness (cont’d) 

Power 

Output (bhp) 

Current PTO NOx 

Limit (ppmv) 

Proposed NOx 

Limit (g/bhp-hr) 

NOx Emission 

Reduction (tons/yr) SIC 

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1000 59 11 3.37 1311

1024 25 11 1.01 1311

1024 25 11 1.01 1311

1215 25 11 1.19 1311

1478 25 11 1.45 1311

1478 25 11 1.45 1311

1478 25 11 1.45 1311

1478 25 11 1.45 1311

1478 25 11 1.45 1311

1493 25 11 1.47 2037

1585 15 11 0.45 4931

1585 15 11 0.45 4931

1585 15 11 0.45 4931

1585 15 11 0.45 4931

1585 15 11 0.45 4931

1585 15 11 0.45 4931

1680 25 11 1.65 1311

1680 25 11 1.65 1311

 

TOTAL 131.5 

(0.360 tons/day) 
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 12 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

Table 3 — Estimated Lean-Burn NOx Reductions for Calculating Cost Effectiveness 

Power 

Output (bhp) 

Current PTO NOx 

Limit (ppmv) 

Proposed NOx 

Limit (ppmv) 

NOx Emission 

Reduction (tons/yr) SIC 

220 75 11 0.91 4952

220 75 11 0.91 4952

220 75 11 0.91 4952

330 75 11 1.36 2911

330 75 11 1.36 2911

450 65 11 1.57 1311

450 65 11 1.57 1311

455 65 11 1.58 1311

577 64 11 1.97 4952

615 65 11 2.14 4941

615 65 11 2.14 4941

620 50 11 1.56 4952

620 65 11 2.16 4952

670 65 11 2.33 4952

892 50 11 2.24 4952

930 65 11 3.24 4953

1,000 123 79 2.85 1311

1,000 123 79 2.85 1311

1,000 123 79 2.85 1311

1,000 148 79 4.46 1311

1,000 148 79 4.46 1311

1,070 65 11 3.72 4941

1,070 65 11 3.72 4941

1,070 65 11 3.72 4941

1,150 65 11 4.00 4922

1,150 65 11 4.00 4911

1,150 65 11 4.00 4911

1,200 65 11 4.17 1311

1,200 65 11 4.17 1311

1,200 65 11 4.17 4941

1,408 65 11 4.90 4922

1,408 54 11 3.88 4952

1,408 62 11 4.66 4952

1,408 62 11 4.66 4952

1,500 65 11 5.22 4922

1,500 65 11 5.22 4922

1,500 148 79 6.69 1311

1,500 148 79 6.69 1311

2,000 65 11 6.96 1311

2,000 65 11 6.96 1311

2,000 65 11 6.96 1311

2,000 144 79 8.41 1311
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 13 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

Table 3 — Estimated Lean-Burn NOx Reductions for Calculating Cost Effectiveness (Cont’d) 

Power 

Output (bhp) 

Current PTO NOx 

Limit (ppmv) 

Proposed NOx 

Limit (ppmv) 

NOx Emission 

Reduction (tons/yr) SIC 

2,000 144 79 8.41 1311

2,000 144 79 8.41 1311

2,000 144 79 8.41 1311

2,000 144 79 8.41 1311

4,000 136 79 14.75 1311

4,000 136 79 14.75 1311

4,000 136 79 14.75 1311

4,000 136 79 14.75 1311

4,000 136 79 14.75 1311

4,445 11.9 11 0.26 4922

4,445 11.9 11 0.26 4922

4,445 11.9 11 0.26 4922

4,445 11.9 11 0.26 4922

5,500 136 79 20.29 1311

5,500 136 79 20.29 1311

5,500 136 79 20.29 1311

5,500 136 79 20.29 1311

5,500 136 79 20.29 1311

5,500 136 79 20.29 1311

TOTALS 390.87 

(1.0709 tons/day) 
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis August 18, 2011 

B - 14 Final Staff Report with Appendices 

For Revised Proposed Amendments to Rule 4702

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