Ezra Wood, Scott Herndon, Luwi Oluwole, Simon Albo 6/21/2011 FLAIR workshop, Austin TX Acknowledgments: TCEQ Characterization of gas and particle emissions in the greater Houston area using the Aerodyne mobile laboratory Ezra Wood, Scott Herndon, Luwi Oluwole, Simon Albo T. Onasch1, E. Fortner1, J. Jayne1, J. Wormhoudt1, P. Massoli1, C. Kolb1, H. B. Lee2, M. Zavala3, L. T. Molina3, and W. B. Knighton4 Aerodyne Research, Inc., Harvard University, Molina Center for Energy & Environment, Montana State University

Instrumentation CO, NO2, C2H4, HCHO (QC-TILDAS) O3, NO, CO2, SO2 aromatic VOCs, 1,3-butadiene, OVOCs (PTR-MS/NO+MS) O3, NO, CO2, SO2 PAN (GC), VOCs (canisters) (UH) Instrumentation Size and chemically-speciated PM (Aerosol Mass Spectrometer) Particle number (CPC) Black Carbon (MAAP), extinction PM size distribution (SMPS) Wind speed/direction Actinic flux GPS position

• quantification (pounds/hr) • location identification Goal: Conduct measurements that support emissions characterization • quantification (pounds/hr) • location identification Mobile sampling: Texas City, Mont Belvieu, Ship Channel Stationary sites: Texas City Mont Belvieu U. Houston

C2H4 and HCHO mapping in Mont Belvieu WIND

Quantification of emissions from “traditional” combustion source: fuel-based emission factors Ship Channel May 28, 2009

Carbon balance method Emission Inventory 58 g NOx/kg fuel 18 ppb NOx / ppm CO2 x total fuel consumption Emission Inventory 58 g NOx/kg fuel

HONO/NOx: 0.7 to 1.4% (similar to on-road diesel vehicles) Ship emission factors Plume time Vessel name/type NOx g/kg fuel dOx/ dNOx HCHO g/kg CO g/kg SO2 10:04 Izumo Princess 58 0.1 10:26 Vega Spring 61 21 10:59 Odfjell Seachem 54 0.06 12 25 11:04 UBC Bremen? 80 0.08 11:05 Eitzen Chemical 50 0.11 0.19 48 34 11:17 Leyte Spirit 89 0.07 0.17 10 37 11:24 tug/ferry 55 0.12 0.40 1.2 11:36 30 0.09 – 0.15 0.13 11:54 Petropavlovsk 44 0.16 17 Williams MSDc 61.5 0.15 11.0 6.3 SSDb 79.6 11.8 27.8 This method works great with good winds. And when mobile, can usually drive around to make the winds work for you. Any decent research grade 1-second instrument can be incorporated into the mix. Daytime, nighttime both work. But still, wind has to be cooperative. Thus this is a good complement to the remote sensing methods that others will talk about. HONO/NOx: 0.7 to 1.4% (similar to on-road diesel vehicles) -based on comparison with UCLA iDOAS HONO/NO2 ratios

use carbon balance method … Flares: use carbon balance method … …with a few complications TCEQ’s Comprehensive Flare Study September 2010: Assumed DRE = 0.98, more like 0.3 to 0.7ish HCHO/CO = 0.02 to 0.05 for propene flare • Destruction Removal Efficiency (DRE) vs. fuel-based emission factors • Assumption that most C ends up as CO, CO2 not valid

Emissions observed with ARI mobile laboratory during FLAIR 2009: 1) Useful correlations between combustion tracers (CO, CO2) and VOCs 2) Obvious fugitive emissions 3) Unclear – no obvious correlation between combustion tracers and VOCs, but can’t rule it out

1. (Useful VOC-COx correlations) Flare Emission Capture from Mobile Laboratory Mobile Lab Maneuvered Here Prevailing Wind Known Plant Flare P-200

Flare Emission Capture from Mobile Laboratory Prevailing Wind This is NOT self sampling. The incoming wind speed is 4-7 mph. VOC/CO ratio invariable, but CO2/CO changes – possibly from a clean CO2 source nearby. C2H4/CO2 ratios higher than highest superemitting on-road vehicle Known Plant Flare P-200 11

Flare Emission Capture from Mobile Laboratory Prevailing Wind There are different CO2 to CO ratios – there seems to be only one VOC to CO ratio & HCHO/CO is RIGHT IN LINE WITH TCEQ Comprehensive Flare Study!! myriad other sources of CO2 Ethylene to formaldehyde ratio is high suggesting ethylene is vent gas (but don’t know for sure). DRE def less than 98%. Known Plant Flare P-200 Carbon balance methods with a guess about vent gas composition: DRE = 94% (88% - 96%) 12

Large ethene leak, Winfree Rd 2) obvious fugitive emissions / non-combustion source Large ethene leak, Winfree Rd ·Localized (<10 m) · no CO/CO2/NOx

(5/19/2009, Mt. Belvieu) Unlit flare 2) obvious fugitive emissions / non-combustion source (5/19/2009, Mt. Belvieu)

3) No obvious correlation between combustion tracers and VOCs, but can’t rule out low DRE flare vs. leak

3) No obvious correlation between VOCs and COx – low DRE flares? (VOC to CO/CO2 ratio believable if DRE < 30%). C2H4 of 200 ppb = 0.4 ppm of C. Low DRE flare could give just a ppm or 2 of CO2 – within the atmospheric noise.

The Aerodyne Inverse Modeling System (AIMS) Driver SCIPUFF SCIPUFF TL/Adjoint Minimization algorithm Obs. Data (MET, Sensors) # of sources, Emission rates, Locations, Start and End times. Given knowledge of the wind history, determine emission source parameters that when applied in atmospheric dispersion model yield pollutant concentration profiles that are most consistent with observed profiles Aerodyne Research, Inc.

Inversion model results Texas City 15 pounds/hr benzene source identified by inversion model WIND

Stationary data: SO2 “upwind” from courthouse site (TC) Stationary data was useful too. Data points projected 5 min back, linearly. Known regeneration facility nearby.

HCHO: same spatial signature filtered day/night

Consistent HCHO/SO2 ratio Each marker (color) is a different transect (90 total). Occasionally there is HCHO w/ little SO2, but usually a consistent HCHO/SO2 ratio.

HCHO: Primary vs. secondary? C2H4 + OH → → 1.43 HCHO photochemical age (OH exposure): What else can we learn from these downwind observations? WE can constrain the photochemical age (OH exposure) by examining the HCHO/C2H4 and HCHO/propene ratios… 22

Primary HCHO in Texas City? slope implies [OH] = 2 ×107 to 4 × 107 molecules/cm3 → evidence for primary HCHO

Primary HCHO from Chevron? C2H4 (ppb) HCHO (ppb) Slope = 0.02 Slope and transit time imply [OH] = 1.33 × 106 molecules cm-3 at 07:20 CST 5/21/2009 → no evidence for primary HCHO

1,3-butadiene mapping (Ship Channel) Goodyear facility – known source of 1,3-butadiene. Were able to measure with Berk Knighton’s “special” 1-second PTR. Luwi will talk more about this facility. WIND

1,3-butadiene, styrene 1,3-butadiene and styrene emitted from different locations.

Summary • Mobile measurements useful for locating and quantifying emission sources • Rich dataset: Marathon flare DRE Ship emission factors Winfree road Ethylene leak Primary HCHO emissions from Texas City facililty Ethylene, propylene emission from Chevron (Mont Belvieu) 1,3-butadiene, styrene from Goodyear

back-up slides

Photochemistry

P(OH) = L(OH) Total OH loss rate = 47.3 s-1, and is dominated by reaction with C2H4. This yields an OH concentation of 1.6 × 105 molecules/cm3. Since the HO2 + NO term is obviously not zero, this number should be considered a lower limit to the true OH concentration. This value is likely higher than the [OH] in non alkene plume air considering the time of day (06:12 local time). Further analysis will address the likely range of values for the HO2 + NO term.