impact of nox emissions in georgia on annual pm2.5

Impact of NOx Emissions in Georgia on Annual PM2.5

Jim Boylan, Byeong-Uk Kim, Michelle Bergin, Jim Kelly

Georgia Department of Natural Resources

9th Annual CMAS ConferenceOctober 12, 2010

Nonattainment in Georgia

• Design value of < 15.0 g/m3

– Average of 2007, 2008, and 2009 observations

• State Implementation Plans– GA EPD has submitted annual PM2.5 SIPs for

Atlanta, Macon, Rome/Floyd, and Chattanooga

• Fine PM Implementation Rule (72 FR 20586)– “The final rule retains provisions for the State or

EPA to conduct a technical demonstration to reverse the presumptive inclusion of NOx” as a PM2.5 attainment plan precursor.

1997 Annual PM2.5 NAAQS

2002 Design Values for Georgia

SANDWICH technique has been applied to 5-year weighted FRM measurements

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Quarter 1 Quarter 2 Quarter 3 Quarter 4 Annual Avg.

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EC

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PBW

NO3

NH4

SO4

Blank

CMAQ Modeling Scenarios

• CMAQ modeling scenarios:– 2009 base case with all emissions included

– 100% state-wide NOx reduction (all sources)



• NOx emission sources include:– Point, Area, On-road, Non-road, Fires, Biogenic

Evaluation Approach• Monitor specific impacts were determined by

taking the difference between the 2009 future design value (with all emissions included) and the sensitivity run design value.

• The modeling results were processed in accordance with EPA’s modeling guidance– SMAT, SANDWICH, and RRFs

• Impacts compared against PSD Significant Impact Levels (SILs) for PM2.5 emissions from a single stationary source– Annual SILs 0.3 g/m3 (which is 2% of the NAAQS)

12-km CMAQ Modeling Domain

100% NOx Reduction in Georgia

- - EPA’s Annual NSR Significant Impact Level (SIL)

Statewide 100% NOx Reduction-1.20

-1.00

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Annual Q1 Q2 Q3 Q4

100% NOx Reduction

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ECOC

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Hourly Model Performance for OCYorkville – July 2002

Organic Carbon in July 2002 @ YRK

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Date

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[ug

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]

OC_02_Typical OC_09_Typical OC dSOMA dSOMB dPSOM dPOM

OC Model Performance

• The CMAQ model shows poor hourly model performance with unrealistically high OC predictions in the early morning hours when the mixing height is low. – It is during these same hours that the model shows large

OC sensitivities to NOx reductions.

• OC modeling is still developing and does not include many import pathways. – Smog chamber studies at Caltech have shown that

reducing NOx emissions can lead to higher SOA production from isoprene, monoterpenes, and aromatic VOC. None of these pathways are currently included in the model.

30% and 50% NOx ScenarioSource Sector 2009 NOx

Inventory

Control Evaluation 2014 Potential

NOx Inventory

2030 Potential

NOx Inventory

EGU Point 97,168.0 Rule (sss) 2015 + Remaining SCR + NG Conversion

35,950.8 35,950.8

Non EGU Point 51,681.7 AirControlNET 27,621.0 27,621.0

On Road Mobile 209,349.2 Fleet turnover 142,353.5 62,804.8

Non Road Mobile

85,732.9 Held Constant 85,732.9 85,732.9

Area

Fire

37,688.9

14,236.6

AirControlNET

Held Constant

36,071.5

14,236.6

36,071.5

14,236.6

Total Inventory 495,857.3 341,966.3 262,417.6

Total Reduction 153,891.0 233,439.7

% Reduction 31.0% 47.1%




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Annual Q1 Q2 Q3 Q4

30% NOx Reduction

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EPA’s PSAT Modeling

PSAT 100% NOx Contribution

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100% NOx Scenario

• The 100% NOx reduction modeling scenario has a number of issues:– This scenario models unrealistic emission

reduction that are far greater than can be realistically achieved

– Most of the modeling response (75% - 85%) is due to reductions in secondary organic carbon

• SOA pathways are highly uncertain and the model does a poor job of simulating hourly OC temporal variations

Conclusions• GA EPD feels it is inappropriate to evaluate the impacts

from a brute force 100% statewide NOx sensitivity • GA EPD feels that a 30% statewide NOx

sensitivity, a 50% statewide NOx sensitivity, or a 100% PSAT source apportionment run would be more appropriate to evaluate NOx impacts. – 30% statewide NOx 0.11 g/m3 (max. impact) – 50% statewide NOx 0.22 g/m3 (max. impact)– 100% statewide PSAT NOx 0.12 g/m3 (max. impact)

• The above modeling scenarios show impacts below the annual PSD SIL and indicate that NOx is “insignificant” as a precursor to PM2.5 in the Georgia nonattainment areas.

Jim Boylan, Ph.D.Georgia Dept. of Natural Resources

4244 International Parkway, Suite 120Atlanta, GA 30354

[email protected] 404-362-4851

Contact Information

impact of nox emissions in georgia on annual pm2.5

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