2007 Area Source Emissions Inventory Methodology 052 AGRICULTURAL IRRIGATION IC ENGINES- NG

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1 San Joaquin Valley AIR POLLUTION CONTROL DISTRICT 2007 Area Source Emissions Inventory Methodology 052 AGRICULTURAL IRRIGATION IC ENGINES- NG I. Purpose This document describes the Area Source Methodology used to estimate emission of carbon monoide (CO), nitrogen oides (NO ), fine particulate matter less then 10 microns (PM 10 ), volatile organic compounds (VOC), and sulfur oides (SO ) from natural gas fired agricultural internal combustion engines used for irrigation in the San Joaquin Valley (SJV) Air Basin. An area source is a collection of similar emission units within a geographic area (ie., a County). Area sources collectively represent individual sources that are small and numerous, and that may not have been inventoried as specific point, mobile, or biogenic sources. The California Air Resources Board (CARB) has grouped these individual sources with other like sources into area source categories. These source categories are grouped in such a way that they can be estimated collectively using one methodology. II. Applicability The emission calculations from this Area Source Methodology apply to the following Category of Emission Source (CES) code and Reconciliation Emission Inventory Code (REIC): Table 1. Emission inventory codes. CES REIC Description Food and Agricultural Processing - Irrigation ICE - NG III. Point Source Reconciliation Emissions from the area source inventory and point source inventory are reconciled against each other to prevent double counting. This is done using relationships created by the California Air Resources Board (CARB) between the area source REIC and the point sources Standard Industry Classification (SIC) code and emissions process Source Category Code (SCC) combinations. The area sources in this methodology reconcile against processes in our point source inventory with the following SIC/SCC combinations : Page 1 of 12 Rev. Date: 09 December 2008

2 Table 2. Point source reconciliation relationships for REIC EIC SIC SCC Point Source Type Internal Combustion Irrigation Systems - Natural Gas - Reciprocating IV. Methodology Description This area source methodology is a top down estimation of emissions from agricultural irrigation pump engines. An agricultural irrigation engine pumps water, either from a surface waterway or a well. Some irrigation engines also pressurize irrigation systems, such as sprinklers. The amount of natural gas delivered to facilities with agricultural or irrigation district SICs in each county within the District was obtained from the California Energy Commission (Gough, 2007). From this, the amount of natural gas reported to the District s point source inventory as consumed was subtracted. The difference between the amount of natural gas reported delivered and the amount reported consumed was considered the area source process rate. To estimate area source emissions, the area source process rate was multiplied by emission factors V. Activity Data Natural gas deliveries to facilities with agricultural SICs was obtained from the California Energy Commission (Gough, 2007). The facility SICs associated with this analysis are presented in Appendi A. The District s point source inventory of agricultural natural gas combustion processes was then reconciled against the amount of natural gas reported delivered to agricultural sources within the District. The area source consumption was calculated as the difference between the agricultural natural gas deliveries and the agricultural consumption reported through the point source inventory (Table 3). Table 3. Agricultural/irrigation district natural gas consumption (2007). County Deliveries Reconciled Area Point Source Reported by CEC Source Consumption Millions of Consumption MMSCF (MMSCF) Therms (MMSCF) Fresno , , Kern , , Kings Madera Merced San Joaquin Stanislaus Tulare Total , , Page 2 of 12 Rev. Date: 09 December 2008

3 VI. Emission Factors Table 4. Natural gas-fired IC engine emission factors (4 stroke, rich 30% thermal efficiency. Pollutant (lb/mmbtu) Emission Factor (lb/mmscf) Source NO ,730 Carl Moyer Program Table B-14a SO District Policy (APR 1720) (1) PM AP-42 (7/00) Table CO ,730 AP-42 (7/00) Table VOC Carl Moyer Program Table B-14a (1) PM 10 value includes both filterable ( lb/mmbtu) and condensable ( lb/mmbtu) emissions. VII. Emissions Calculations A. Assumptions 1. Natural gas deliveries to Ag and Water Pump facilities are accurately reported by the California Energy Commission. 2. All of the natural gas delivered to Ag and Water Pump facilities was consumed by engines. 3. The AP-42 emission factors selected for reciprocating engines are representative. 4. All non-permitted natural gas powered internal combustion engines within the District are 4-stroke rich-burn engines. 5. The heat content of natural gas is 1,000 Btu/scf. 6. Engines operate at 30% thermal efficiency. B. Sample Calculations The emissions for each criteria pollutant within this area source methodology can be calculated using the following equation: Emissions tons yr = Fuel Consumption MMSCF yr Emission Factor lbs of Emissions MMSCF 1ton 2000 lbs For NO emissions due to natural gas combustion in agricultural irrigation engines in Fresno County: Page 3 of 12 Rev. Date: 09 December 2008

4 Given: 1. The reconciled area source consumption of natural gas by agricultural engines in Fresno County was 1,384 MMSCF (million std. cubic feet) in The NO emission factor for natural gas-fired agricultural engines is 2,730 pounds per million cubic feet of natural gas burned. Calculate Emissions: 1,384 MMSCF 2, 730 lb of NO 3, 778,320 lbs of NO Emissions = = Year MMSCF Year NO 3, 778,320 lbs of NO 1 ton 1,889 tons of NO Emissions = = Year 2,000 lbs Year NO VIII. Temporal Variation A. Daily: CARB Code hours per day - uniform activity during the day. B. Weekly: CARB Code 7. Uniform activity. C. Monthly: Agricultural irrigation pumps operate at various times during any given operating day. It is, however, the monthly variation that proves most significant for this category and for the contribution to ecessive ozone formation, which is a summer phenomenon. The monthly temporal profile for agricultural irrigation pumps was developed by Sonoma Technology, Inc. (STI, 1996), and is presented in the table below. Page 4 of 12 Rev. Date: 09 December 2008

5 Table 5. Monthly relative activity for agricultural irrigation pump engines. Month (2007) Activity Level (%) January 4.4% February 4.4% March 4.4% April 11.5% May 11.5% June 11.5% July 13.4% August 13.4% September 13.4% October 4.1% November 4.0% December 4.0% Total 100.0% IX. Spatial Variation Natural gas deliveries to agricultural sources in 2007 for each county in the SJV Air Basin were provided by the California Energy Commission. This information was previously presented Section V. Within each county, activity can be assigned to parcels zoned for agricultural activity. X. Growth Factor Growth factors are developed by either the District s Planning Department or CARB for each EIC. These factors are used to estimate emissions in future years. The growth factors associated with this emissions category may be obtained from the Air Quality Analysis Section of the District s Planning Department. XI. Control Level Control levels are developed by either the District s Planning Department or CARB for each EIC. Control levels are used to estimate emissions reductions in future years due to implementation of District rules. These control levels take into account the effect of control technology, compliance and eemptions at full implementation of the rules. Control levels associated with this emissions category may be obtained from the Air Quality Analysis Section of the District s Planning Department. Emission units within this area source category may be subject to the following District Rules: Page 5 of 12 Rev. Date: 09 December 2008

6 Table 6. District Rules applicable to REIC Rule No Rule Description 4701 Internal Combustion Engines Phase Internal Combustion Engines Phase 2 XII. CARB Chemical Speciation CARB has developed organic gas profiles in order to calculate reactive organic gasses (ROG), volatile organic compounds (VOC) or total organic gas (TOG) given any one of the three values. For each speciation profile, the fraction of TOG that is ROG and VOC is given. The organic gas profile codes can also be used to lookup associated toics. CARB s organic gas speciation profile for agricultural natural gas IC engines is presented in Table 7. Table 7. CARB organic gas speciation profiles for CARB Fractions Profile Description Organic Gas ROG VOC Profile# I.C. Engines Reciprocating Natural Gas CARB has developed particulate matter speciation profiles in order to calculate particulate matter (PM), particulate matter with a diameter less than or equal to 10 microns (PM 10 ) or particulate matter with a diameter less than or equal to 2.5 microns (PM 2.5 ) given any one of the three values. For each speciation profile, the fraction of PM that is PM 10 and PM 2.5 is given. The particulate matter profile codes can also be used to lookup associated toics. CARB s speciation profiles for agricultural natural gas IC engines is presented in Table 8. Table 8. CARB particulate matter speciation profiles for CARB PM Fractions Profile Description Profile# PM 10 PM 2.5 Stationary I.C. Engines - Natural Gas XIII. Assessment Of Methodology This area source estimate relies on information provided by the California Energy Commission for total natural gas deliveries to agricultural and irrigation district facilities. In order to validate the estimate, the number of natural gas-fired irrigation engines in the District was back-calculated from the CEC natural gas delivery data as using the following assumptions: Engines are 219 hp on average (District s permit and Emissions Reduction Incentive Program databases). Engines operate 2,500 hours per year on average. Page 6 of 12 Rev. Date: 09 December 2008

7 One hp consumes 2,542.5 Btu of energy in one hour. The heat content of natural gas is 1,000 Btu/scf. Engines operate at 30% thermal efficiency. There were 4, MMSCF of natural gas delivered to agricultural facilities in the District in The load factor is assumed to be 65% for agricultural irrigation pump engines based on etensive discussions with engine dealers, manufacturers, and irrigation eperts. Using this information, the amount of natural gas consumed by one natural gas irrigation engine can be estimated as follows: Scenario 1: Fuel consumption at 100% load. MMSCF 1 Engine 219 HP 2,500 Hrs 2,542.5 BTUs 1 Hp Input 1 SCF = Engine Engine HP Hr 0.30 Hp Output 1,000 BTU 1 MMSCF 100% Load 1,000,000 SCF MMSCF = Engine Scenario 2: Fuel consumption at 65% load. MMSCF = 1 Engine 219 HP 2,500 Hrs Engine Engine 2,542.5 BTUs HP Hr 1 Hp Input 0.30 Hp Output 1 SCF 1,000 BTU 1 MMSCF 1,000,000 SCF 65% Load MMSCF = Engine Then, the number of natural gas-fired irrigation engines in the District is estimated by dividing the total amount of natural gas delivered to agricultural facilities in the District by the amount of natural gas consumed by each engine as follows: Scenario 1: Fuel consumption at 100% load. 1 Engine Engines Number = 4,990.57MMSCF Delivered MMSCF Engines Number = 1,076 Scenario 2: Fuel consumption at 65% load. Engines Number = 4, MMSCF Delivered 1 Engine 3.02 MMSCF Engines Number = 1,653 Page 7 of 12 Rev. Date: 09 December 2008

8 This estimate of 1,076 to 1,653 engines seems reasonable compared to the range of values (755-1,500) we have received from other sources. XIV. Emissions Following is the 2007 area source emissions inventory for REIC estimated by this methodology. Emissions are reported for each county in the District. Table 9. Area source emissions for REIC (2007). County Emissions (tons/year) NO CO SO VOC (1) PM 10 (2) PM 2.5 Fresno 1, , N/A Kern 2, , N/A Kings N/A Madera N/A Merced N/A San Joaquin N/A Stanislaus N/A Tulare 1, , N/A TOTAL 6, , N/A (1) The District only reports ROG to CARB. As noted in Section XII, ROG is the same as VOC. (2) At this time, the District does not calculate PM2.5 emissions. PM2.5 emissions can be estimated using the speciation profiles found in Section XII. Following is the 2007 point source emissions inventory for REIC as reported to the District by our permit holders. Emissions are reported for each county in the District. Table 10. Point source emissions for REIC (2007). County Emissions (tons/year) NO CO SO VOC (1) PM 10 (2) PM 2.5 Fresno N/A Kern N/A Kings N/A Madera N/A Merced N/A San Joaquin N/A Stanislaus N/A Tulare N/A TOTAL N/A (1) The District only reports ROG to CARB. As noted in Section XII, ROG is the same as VOC. (2) At this time, the District does not calculate PM2.5 emissions. PM2.5 emissions can be estimated using the speciation profiles found in Section XII. Page 8 of 12 Rev. Date: 09 December 2008

9 Following is the 2007 total unreconciled (point source plus area source) emissions inventory for REIC Emissions are reported for each county in the District. Table 11. Total emissions for REIC (2007). County Emissions (tons/year) NO CO SO VOC (1) PM 10 (2) PM 2.5 Fresno 1, , N/A Kern 2, , N/A Kings N/A Madera N/A Merced N/A San Joaquin N/A Stanislaus N/A Tulare 1, , N/A TOTAL 6, , N/A (1) The District only reports ROG to CARB. As noted in Section XII, ROG is the same as VOC. (2) At this time, the District does not calculate PM2.5 emissions. PM2.5 emissions can be estimated using the speciation profiles found in Section XII. CARB s CEIDARS database does not record any emissions for this source category in 2005 or Following is the net change in total unreconciled emissions between this update (2007 inventory year) and the previous update (2006 inventory year) for REIC The change in emissions are reported for each county in the District. Table 12. Net emissions change for REIC ( ). County Emissions (tons/year) NO CO SO VOC (1) PM 10 (2) PM 2.5 Fresno 1, , N/A Kern 2, , N/A Kings N/A Madera N/A Merced N/A San Joaquin N/A Stanislaus N/A Tulare 1, , N/A TOTAL 6, , N/A (1) The District only reports ROG to CARB. As noted in Section XII, ROG is the same as VOC. (2) At this time, the District does not calculate PM 2.5 emissions. PM 2.5 emissions can be estimated using the speciation profiles found in Section XII. Page 9 of 12 Rev. Date: 09 December 2008

10 XV. Revision History This is a new District methodology. XVI. Update Schedule In an effort to provide inventory information to CARB and other District programs and maimize limited resources, the District has developed an update cycle based on emissions within the source category as shown in Table 13. Table 13. Area source update frequency criteria. Total Emissions (tons/day) Update Cycle (years) <=1 4 >1 and <= >2.5 and <=5 2 >5 1 Since NO emissions eceed 5 tons per day, this area source estimate will be updated every year. Table 14. Natural gas agricultural irrigation engine methodology update frequency. Source of Emissions Frequency EIC (Point Source Inventory / Data (years) Gathering) Data Gathering XVII. References 1. California Air Resources Board Attachment 2, Appendi D: Emission inventory methodology, agricultural irrigation pumps diesel. August 2006, 20 pages. 2. California Air Resources Board Section 1.1: Agricultural irrigation pumps diesel. April 2003, 4 pages. 3. California Air Resources Board Ag advisory materials: Forecasting air pollution emission from agricultural operations in the San Joaquin Valley. May 2003, 2 pages. 4. California Air Resources Board Ag advisory materials: Attachment 3 ROG and NO emissions, agricultural irrigation pumps, San Joaquin Valley. May 2003, 3 pages. Page 10 of 12 Rev. Date: 09 December 2008

11 5. Gough, A., ed 2006 natural gas delivery data from the California Energy Commission, Sacramento, CA to Yu Vu, San Joaquin Valley Unified APCD. (May 30, 2007). 6. Sacramento Metropolitan Air Quality Management District Stationary agricultural irrigation internal combustion engines (stationary agriculture irrigation pumps). 4 pages. 7. Sonoma Technology, Inc Emission inventory of agricultural internal combustion engines used for irrigation in the SJVUAPCD. 104 pages. 8. United States Department of Agriculture, National Agricultural Statistics Service Census of Agriculture: 2003 farm and ranch irrigation survey. November 15, 2004; 216 pages United States Environmental Protection Agency AP 42, Fifth Edition, Volume I, Chapter 3.2: Stationary internal combustion sources, natural gas fired reciprocating engines. XVIII. Appendices Appendi A. Agricultural and Water Pump SIC Codes. Page 11 of 12 Rev. Date: 09 December 2008

12 XIX. Appendi A. Agricultural and Water Pump SIC Codes. Table 15. Agricultural and water pump SIC codes. SIC Group SIC Codes Agricultural Production-Crops 111, 112, 115, 116, 119, 131, 132, 133, 134, 139, 161, 171, 172, 173, 174, 175, 179, 181, 182, 191 Agricultural Production-Livestock 211, 212, 213, 214, 219, 241, 251, 252, 253, 254, 259, 271, 272, 273, 279, 291 Forestry 811, 831, 851 Fishing, Hunting, And Trapping 912, 913, 919, 921, 971 Electric, Gas, Sanitary Services 4971 Page 12 of 12 Rev. Date: 09 December 2008