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

6/21/2011FLAIR workshop, Austin TXAcknowledgments: TCEQ

Aerodyne Research, Inc., Harvard University, Molina Center for Energy & Environment,Montana State University

CO, NO2, C2H4, HCHO (QC-TILDAS)

aromatic VOCs, 1,3-butadiene, OVOCs (PTR-MS/NO+MS)

O3, NO, CO2, SO2

PAN (GC), VOCs (canisters) (UH)

Size and chemically-speciated PM (Aerosol Mass Spectrometer) Particle number (CPC)Black Carbon (MAAP), extinctionPM size distribution (SMPS)

Wind speed/directionActinic fluxGPS position

Instrumentation

Goal: Conduct measurements that support emissions characterization • quantification (pounds/hr) • location identification

Mobile sampling: Texas City, Mont Belvieu, Ship Channel

Stationary sites:Texas CityMont BelvieuU. 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

58 g NOx/kg fuel

18 ppb NOx / ppm CO2

x total fuel consumptionEmission

Inventory

Ship emission factors

Plume time

Vessel name/type

NOx

g/kg fuel

dOx/dNOx

HCHOg/kg

CO g/kg

SO2

g/kg

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 12 1.2

11:36 tug/ferry 30 0.09 – 0.15

0.13

11:54 Petropavlovsk 44 0.07 0.16 17 30

Williams MSDc 61.5 0.15 11.0 6.3

Williams SSDb 79.6 0.15 11.8 27.8

HONO/NOx: 0.7 to 1.4% (similar to on-road diesel vehicles)-based on comparison with UCLA iDOAS HONO/NO2 ratios

• Destruction Removal Efficiency (DRE) vs. fuel-based emission factors• Assumption that most C ends up as CO, CO2 not valid

Flares: use carbon balance method …

…with a few complications

TCEQ’s Comprehensive Flare StudySeptember 2010:

Emissions observed with ARI mobile laboratoryduring 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

Known Plant Flare P-200

Mobile Lab Maneuvered Here

Prevailing Wind

Flare Emission Capture from Mobile Laboratory

Known Plant Flare P-200

Prevailing Wind

Flare Emission Capture from Mobile Laboratory

Known Plant Flare P-200

Prevailing Wind

Carbon balance methods with a guess about vent gas composition:

DRE = 94% (88% - 96%)

Large ethene leak, Winfree Rd

·Localized (<10 m)

· no CO/CO2/NOx3304

3303

UT

M N

orth

ing

(km

)

317316

UTM Easting (km)

2001000

C2H4 (ppbv)

2) obvious fugitive emissions / non-combustion source

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

Unlit flare

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?

The Aerodyne Inverse Modeling System (AIMS)

• 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

Driver

SCIPUFF SCIPUFF TL/AdjointMinimizationalgorithm

• Obs. Data (MET, Sensors)

Aerodyne Research, Inc.

# of sources,Emission rates, Locations, Start and End times.

WIND15 pounds/hr benzene sourceidentified by inversion model

Inversion model results

Stationary data: SO2 “upwind” from courthouse site (TC)

HCHO: same spatial signature filtered day/night

Consistent HCHO/SO2 ratio

HCHO: Primary vs. secondary?

C2H4 + OH → → 1.43 HCHO

42

42

1)(43.1

)(ln

][HCOHk

tHC

tHCHO

OHt

photochemical age (OH exposure):

Primary HCHO in Texas City?

slope implies [OH] = 2 ×107 to 4 × 107 molecules/cm3

→ evidence for primary HCHO

Primary HCHO from Chevron?

Slope and transit time imply [OH] = 1.33 × 106 molecules cm-3 at 07:20 CST

5/21/2009 → no evidence for primary HCHO

C2H4 (ppb)

HC

HO

(p

pb)

Slope = 0.02

80400

1,3-butadiene (ppb)

WIND

1,3-butadiene mapping (Ship Channel)

1,3-butadiene, styrene

Summary• Mobile measurements useful for locating and quantifying emission sources

• Rich dataset:Marathon flare DREShip emission factorsWinfree road Ethylene leakPrimary HCHO emissions from Texas City facililtyEthylene, propylene emission from Chevron (Mont Belvieu)1,3-butadiene, styrene from Goodyear

back-up slides

Photochemistry

80

60

40

20

0

prop

ene

ppb

5:08 AM5/21/2009

5:12 AM 5:16 AM 5:20 AM

CST

300

200

100

0

C2H

4 pp

b

460

440

420

400

CO

2 pp

m

2000

1500

1000

500

0

CO

120

80

40

0

NO

x (p

pb)

0.8

0.6

0.4

0.2

0.0

P(H

Ox)

ppt

/s

12

8

4

0

m/z

57

bute

ne

P(HOx) from O3 + eth, prop, butenes

P(OH) = L(OH)

][

]][[]][[][ 233

iXiOH

OHalkenesOSS Xk

NOHOkYalkenesOkOH

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.