APPENDIX B 

Emission Reduction Analysis for Amendments to 

Rule 4308 (Boilers, Steam Generators, and Process Heaters - 

0.075 MMBtu/hr to less than 2.0 MMBtu/hr) 

December 17, 2009 
SAN JOAQUIN UNIFIED VALLEY AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis for Rule 4308 December 17, 2009 

B-2 

Final Staff Report with Appendices 

 For Amendments to Rule 4308

 

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SAN JOAQUIN UNIFIED VALLEY AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis for Rule 4308 December 17, 2009 

B-3 

Final Staff Report with Appendices 

 For Amendments to Rule 4308

 

ESTIMATED EMISSIONS REDUCTIONS FROM BOILERS, STEAM 

GENERATORS, AND PROCESS HEATERS – 

 0.075 MMBtu/hr to less than 2.0 MMBtu/hr 

I. SUMMARY 

The District estimated in its 2008 PM2.5 Plan that the 2009 emissions baseline is 

3.59 tons per day (tpd) of NOx and 3.3 tpd of SOx are emitted in the SJVAB from 

this source category. The new estimated NOx emissions and emissions 

reduction are summarized in Table B-1 and detailed in Section III. 

Table B-1 Summary of Baseline Emissions and Emission Reductions 

Size (MMBtu/hr) Baseline NOx 

(tpd) 

NOx 

Reductions 

(tpd) 

Percent Reductions

> 0.075 but < 0.4 1.03 0.77 75% 

> 0.4 but < 2.0 2.36 2.0 85% 

Total 3.39 2.77 82% 

 

II. CALCULATION METHODOLOGY 

A. Data Source 

District staff gathered data from stakeholders, manufacturers and the SCAQMD 

to determine emission capacity factors, emission rates, average unit size and unit 

population. District staff extrapolated data from the SCAQMD’s staff report on 

Rule 1146.2 (2007) to estimate the number of units located in the SJVAB. 

The SJVAPCD sent out a survey to try to gather information on the number of 

units in this size category. However, only 50% of surveys were returned, and 

most of them did not contain any information on the number of units for this size 

category. Therefore, District staff calculated the population-to-unit ratio, using 

information from Bay Area and South Coast staff reports, in order to derive the 

number and size of units needed to support the human population in the SJVAB. 

District staff found that for every 350 people there is one unit in the size range of 

0.075 MMBtu/hr to 0.4 MMBtu/hr and that for every 750 people there is one unit 

in the size range of greater than 0.4 MMBtu/hr to less than 2.0 MMBtu/hr. 

Multiplying the Valley’s estimated population of 4.2 million people (in 2010) by 

the population-to-unit ratios, District staff estimated the unit inventory shown in 

Table B-2. 
SAN JOAQUIN UNIFIED VALLEY AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis for Rule 4308 December 17, 2009 

B-4 

Final Staff Report with Appendices 

 For Amendments to Rule 4308

 

District staff also used the average emission rates derived by the SCAQMD to 

calculate the baseline emissions for this category. In South Coast’s 

implementation studies for Rule 1146.2 the average emission rate was110 ppm 

(0.136 lb NOx/MMBtu) for units in this size category. This accounts for units that 

are considerably older and also for ones that have not had continual 

maintenance and upkeep. 

A capacity factor of 0.22 was used to develop baseline emissions. The capacity 

factor was derived by the SCAQMD and BAAQMD and represents the fraction of 

fuel actually burned or consumed by the unit in a year compared to the 

theoretical maximum amount of fuel that a unit could use in a year. A 0.22 

capacity factor was determined from the statistical survey conducted by the 

South Coast AQMD and was developed from unit operation and fuel usage 

information provided in that survey. Bay Area AQMD used information from the 

local gas company and surveys to users to determine the typical usage for these 

units. 

B. Assumptions for the Emissions Reductions Analysis 

District staff used the unit population, the emission rates and capacity factor to 

calculate the estimated NOx reductions that would be achieved upon the 

compliance of the draft rule requirements. Because of a lack of input and data, 

District staff has assumed certain specifications to perform the cost effectiveness 

analysis. More information from stakeholders and other organizations would help 

to improve the analysis in future staff reports. The following are some of the 

assumptions that were made: 

1. In order to account for the worst case scenario, District staff assumed the 

units operated 24 hours a day. 

2. A 0.22 capacity factor was assumed based on South Coast Rule 1146.2 

information. 

3. An average rating was applied to the two size categories since the number 

of units is assumed to be distributed evenly. For example, for the larger 

unit category, the calculation was (0.4 + 2.0) ÷ 2 = 1.2 MMBtu/hr. 

4. The emissions rate is still the same as what South Coast Implementation 

Study found a few years ago. 

Table B-2: Estimated Number of Units For the SJVAB Based on Population

Total Inventory of Units 17,600 

Inventory > 0.075 but < 0.4 12,000 

Inventory > 0.4 but < 2.0 5,600 
SAN JOAQUIN UNIFIED VALLEY AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis for Rule 4308 December 17, 2009 

B-5 

Final Staff Report with Appendices 

 For Amendments to Rule 4308

 

C. Baseline Emissions 

Equations 1 and 2 below show the calculations to estimate baseline emissions. 

The methodology for the equations is also given. The number of units is based 

on the population-to-unit ratio shown in Table B-2. The average rating used in the 

calculations is based on the mean value of the two different size categories. Also, 

an emissions rating of 0.136 lbs NOx/MMBtu was used in order to have a 

conservative estimate of baseline emissions and is based on SCAQMD’s 

Implementation Studies for Rule 1146.2 results. 

Equation 1 - Emissions for Units 0.075 MMBtu/hr - < 0.4 MMBtu/hr

Emissions = (No. of units) x (average rating) x (emission rate) x (capacity factor) 

 x (hours/day) x (ton/lb) 

Emissions = 12,000 x 0.238 MMBtu/hr x 0.136 lb NOx/MMBtu x 0.22 

 x 24 hr/day x 1 ton/2,000 lb 

Emissions = 1.03 tons NOx/day 

Equation 2 - Emissions for Units > 0.4 MMBtu/hr - < 2.0 MMBtu/hr

Emissions = (No. of units) x (average rating) x (emission rate) x (capacity factor) 

 x (hours/day) x (ton/lb) 

Emissions = 5,600 x 1.2 MMBtu/hr x 0.136 lb NOx/MMBtu x 0.22 

 x 24 hr/day x 1 ton/2,000 lb 

Emissions = 2.36 tons NOx/day 

The total baseline emission inventory of 3.39 (1.03 + 2.36) tons NOx per day tpd 

is estimated for this proposed rule. 

III. EMISSION REDUCTION CALCULATIONS 

Using the rule limits for PUC-gas fired units < 0.4 MMBtu/hr and units > 0.4 

MMBtu/hr and their associated capacity factor and baseline emissions, the 

emissions reduction can be estimated as follows: 

Emissions Reductions = 













× ×∆ × × ×

lb

tons

day

hrs No.of Units mean rating of unitsfor category emissionslimits capacity factor 
SAN JOAQUIN UNIFIED VALLEY AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis for Rule 4308 December 17, 2009 

B-6 

Final Staff Report with Appendices 

 For Amendments to Rule 4308

 

For the number of units, District staff continued to use the population-to-unit ratio 

estimates. The average rating is the mean between the lowest and highest size 

units for that category. As of yet, District staff still does not have information on 

the number of units to know how better to weigh the average rating for the 

categories. The change in emissions is from the current rule requirement to the 

proposed emission limits. District staff estimated the number of typical units to be 

80% and the number of instantaneous water heaters and pool heaters to be 20% 

of the total estimated number for this category. The District staff is looking for 

further stakeholder input on what percentage of units in the SJVAB are used in 

these tankless water heater and typical units categories. 

A. TOTAL EMISSIONS REDUCTIONS IN TPD 

The daily emissions reductions that are calculated below estimate the total 

emissions reductions achieved after full implementation of the rule. Because this 

rule is a point of sale rule, these reductions will be achieved over a 20 year 

period. 

1) Units ≥ 0.075 MMBtu/hr to < 0.4 MMBtu/hr: 

Emissions Reductions = 

day

0.67 tons Emissions Reductions 1 =

2,000 lbs

1 ton

day

hr 

 0.22 24 

MMBtu

lb 9,600 0.238 MMBtu (0.136 - 0.0247)

×

 × ×











× ×

Emissions Reductions for Instantaneous and Pool Heaters = 

day

0.10 tons EmissionsReductions 1 =

2,000 lbs

1 ton

day

hr 

 0.22 24 

MMBtu

lb 2,400 0.238 MMBtu (0.136 - 0.068)

×

× ×











× ×

Total Emission Reductions for this Size Category = 0.77 tpd 
SAN JOAQUIN UNIFIED VALLEY AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis for Rule 4308 December 17, 2009 

B-7 

Final Staff Report with Appendices 

 For Amendments to Rule 4308

 

2) Units > 0.4 MMBtu/hr to < 2.0 MMBtu/hr: 

Because the emission limits for Instantaneous Water heaters and Pool 

heaters for this size category are the same as other units, there is no need for 

a separate emission calculation. 

Emissions Reductions = 

day

tons Emissions Reductions = 2 2.0

 

2,000lbs

1 ton

day

hrs

 0.22 24 

MMBtu

lb 5,600 1.2 MMBtu (0.136- 0.0247)*

×

× ×











× ×

Total Emission Reductions for this Size Category = 2.0 tpd 

The emissions reductions from 0.075 -0.4 and the 0.4 – 2.0 need to be added 

together for the total expected emissions reductions from this rule. 

Total Emissions Reduction for Both Size Categories = 2.77 tpd 

B. ANNUAL EMISSIONS REDUCTIONS 

District staff then took this emission reductions information to calculate the 

emissions reductions on a yearly basis. The number of units is based on how 

many units should be replaced each year in the different size categories. 17,600 

units will be replaced over 20 years comes out to 882 units per year. Of the 882 

units, 68% should be 0.075 - 0.4(small units) and 32% should be 0.4 - 2.0 (large 

units).These calculations will show how many reductions can be expected on a 

yearly basis, spread over a 20 year period because of the useful life of a typical 

unit. 

1) For Units ≥ 0.075 MMBtu/hr to < 0.4 MMBtu/hr: 

Emissions Reductions for Regular Units = 

year

12.3 tons Emissions Reductions 1 =

 1 year

365 days

 x 

2,000 lbs

1 ton

day

hr 

 0.22 24 

MMBtu

lb 480 units per year x 0.238 MMBtu (0.136 - 0.0247)

×

× ×











×
SAN JOAQUIN UNIFIED VALLEY AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis for Rule 4308 December 17, 2009 

B-8 

Final Staff Report with Appendices 

 For Amendments to Rule 4308

 

Emissions Reductions for Instantaneous and Pool Heaters = 

year

2.0 tons EmissionsReductions 1 =

 1 year

365 days

 x 

2,000 lbs

1 ton

day

hr 

 0.22 24 

MMBtu

lb 120 units per year 0.238 MMBtu (0.136 - 0.068)

×

× ×











× ×

Total Emissions for this Size Category = 15.3 tpy 

2) For Units > 0.4 MMBtu/hr to < 2.0 MMBtu/hr: 

day

36.3 tons Emissions Reductions = 2

 1 year

365 days

 x 

2,000 lbs

1 ton

day

hrs

 0.22 24 

MMBtu

lb 282 units per year 1.2 MMBtu (0.136 - 0.0247) *

×

 × ×











× ×

Total Emissions for this Size Category = 36.3 tpy 

The emissions reductions from 0.075 -0.4 and the 0.4 – 2.0 size category need to 

be added together for the total expected emissions reductions from this rule. 

Total Emissions Reduction for Both Size Categories = 51.6 tpy 

C. EMISSIONS REDUCTIONS FOR ATTRITION RULE 

District staff then took the total emissions reductions on a yearly basis and 

converted it to tons per day per unit. This annual amount of reductions should 

happen in a linear fashion over the 20 year period, because of older unit 

replacement with lower polluting units. 

51.6 tpy x 1 year/365 day = 0.141 tpd each year over a 20 year period 

Total Emissions Reduction for Both Size Categories = 0.141 tpd each year 

 for 20 years 
SAN JOAQUIN UNIFIED VALLEY AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis for Rule 4308 December 17, 2009 

B-9 

Final Staff Report with Appendices 

 For Amendments to Rule 4308

 

The emission reductions will be over a 20 year period, so the expected total 

emissions reductions of 2.77 tpd, calculated in Section III A, should be achieved 

by 2031. Table B-3 shows how this rule will still meet the District’s plan 

commitments for NOx emissions reductions. 

IV. OTHER 

The District expects there to be a desire to replace old units with newer units 

because many of the new, lower-emitting units are also fuel and energy efficient. 

Many of these units actually give the location an energy savings from older units. 

As more advanced technology become more readily available, more emissions 

reductions may occur from this rule. 

B-3: Emissions Reductions Plan Commitment 

Year for Reductions Plan Commitment 

(annual avg) 

Rule Emission 

Reductions 

2011 0.12 tpd 0.14 tpd 

2012 0.27 tpd 0.28 tpd 

2013 0.39 tpd 0.42 tpd 

2014 0.55 tpd 0.56 tpd 
SAN JOAQUIN UNIFIED VALLEY AIR POLLUTION CONTROL DISTRICT 

Appendix B: Emission Reduction Analysis for Rule 4308 December 17, 2009 

B-10 

Final Staff Report with Appendices 

 For Amendments to Rule 4308

 

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