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QUANTIFICATION OF METHANE SOURCE LOCATIONS AND EMISSIONS IN AN URBAN SETTINGB51Q Characterizing, Modeling, and Extending Urban Metabolism II
Eric Crosson, Picarro
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Quantification of Methane Source Locations and emission in an urban setting
• Contributors:– NOAA – Colm Sweeney Jocelyn Turnbull– Boston University – Nathan Phillips, Lucy Hutyra– Gas Safety Inc. - Robert Ackley– Picarro – Sze Tan, Chris Rella– Purdue University - Paul Shepson, Maria Obiminda Cambaliza– NIST - James Whetstone, Tony Bova, Kuldeep R. Prasad – NASA- Richard Koyler– Penn State University – Ken Davis, Scott Richardson
3
Motivation
• The identification and quantification of greenhouse gas emissions from urban centers are becoming of more interest.
• Recent measurements indicate that urban emissions are a significant source of Methane (CH4) and in fact may be substantially higher than current inventory estimates.
• As such urban emissions could contribute 7-15% to the global anthropogenic budget of methane*.
* Wunch, D., P.O. Wennberg, G.C. Toon, G. Keppel-Aleks, and Y.G. Yavin, Emissions of Greenhouse Gases from a North American Megacity, Geophysical Research Letters, Vol. 36, L15810, doi:10.1029/2009GL)39825, 2009.
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The Problem: Quantifying CH4 Emissions using a Network of Analyzers, Establishing priors.
Tall or Cell Phone Towers
GHG emissions extracted usingWRF-CHEM inversion models
• For CO2- use inventories such as Vulcan as a starting point.
• For CH4- no such starting point exist.
5
• Develop methodologies to identify methane source locations and gather information on methane flux signals to use as priors.– Total methane emissions.– Partition methane emissions both by source and
geographically within an urban center.– Develop methods that enable fast and accurate data
collection and “real time” processing.
Objectives of this effort
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Measurements
Real-timeMet data
AtmosphericModels
Oil & Gasprocessing
10
kg/m
in
EmissionsMaps
Taking a “snap shot”: Speed, specificity, and real-time feedback are the keys to success
A powerful combination of new technologies is enabling scientist to generate high quality data at rates never before possible.
auto
flight
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Speed is “everything”: Getting a “snap shot”, lot of area to cover in precious little time
0 10 20 30 40 50 600
5
10
15
20
Meth
ane C
oncentr
aio
n (
ppm
)
Time (minutes)
Brisbane, CA
Bay Area: 21,442 miles of road**Metropolitan Transportation Commission (2003)
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Accuracy- What is the source?
PetroleumFacility
UncultivatedAreas
Brackishwater
Little or no wind
Brisbane, CA
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Methane Signals Can be Confusing
Natural Gas Vehicles
Inefficient Vehicles
Storm Drains
Natural Gas Leaks
Sewer Systems
Petroleum Facilities
Landfills
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Specificity: isotopic carbon-13 CH4 measurements
How can one help to identify the source?
0.0 0.1 0.2 0.3 0.4 0.5
-46
-44
-42
-40
-38
-36
0.0 0.1 0.2 0.3 0.4 0.5
-46
-44
-42
-40
-38
-36
- 45.7 per mil
PG&E Natural Gas (East Bay) = -37 per milAmbient = -45 per mil
3671 16th Street, San Francisco, CA
De
lta
13 C
H4 (
pe
r m
il)
1/CH4 Concentration (ppm-1)
- 37.2 per mil
-37.2 per mil
-45.7 per mil
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Specificity: isotopic measurements while driving at the speed of traffic
Natural gasConc (ppm)
Delta (permil)
Unknown
Brisbane, CA
Brisbane, CA
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Brisbane Site: looking from another angle
Brisbane, CA
PetroleumFacility
Delta = -53.3 per mil
UncultivatedAreaOld Landfill
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Methane Capture System Leaks
Brisbane, CA
PetroleumFacility
Old Landfill
Delta = -53.3 per mil
Large Area Leak
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Old landfill releasing methane in only two ways
1. Pipe connectors leaks.
2. Methane capture system is failing in one area of landfill.
Take away: In a very short time, able to identify specific problems that may or may not be easily rectified by landfill owner or city fathers.
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Quantifying Methane Source Emissions
• Driving speeds of 20-30 mph
• Vacaville landfill
• Late evening wind conditions were very stable:– Speed 8.2 ±1.3
m/s– Direction 224.2 ±
5.0 deg
wind
• This was late evening with a very flat topography – estimated stability class is E or F (
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Analyzing line integration data in real time to provide immediate feedback
• Post process data using more complex models at a later time
Source Location from model
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Flux chamber measurements obtained using fast, high precision CH4 analyzers.
-26.
25
-22.
5-2
0
-17.
5
-16.
25
-13.
75
-12.
5-1
0
-8.7
5
-6.2
5-5
-2.5
-1.2
5 02.
53.
75 56.
258.
75 10
13.7
517
.520
05
101520253035
-2 4.00
45 feet
4 feet
Leak
Flu
x
• Using chamber measurements, one can obtain a lower limit on the total leak rate
• Found leaks ranging from 40 -300 sccf/day.
• As a guideline, the natural gas used in the “average” American home is 200 standard cubic ft per day.
Leak Rate > 41 cubic ft per day
Methane is coming out of the road.
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Ready to tackle more complex systems?.....Methane Emissions in Indianapolis
Wind direction, Day 2
Methane Concentration levels are 3 times ambient 4 km from the landfill.
Wind direction, Day 1
Emissions from these locations on landfill
Little or no emissions from waste water treatment plant
Unknown source of methane
Natural Gas leak after gas station fire a few
days earlier
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Summary
• Developed fast methodologies for identifying methane source locations and gathering information on methane flux signals to use as priors.
• For 2012:– Continue developing fast methodologies– Measure methane emission in several urban centers
• Indianapolis• Boston• San Francisco / Bay Area• Paris
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