preliminary measurements from the natural gas system in california: from well to downstream of the...
TRANSCRIPT
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Preliminary measurements from the natural gas system in California: from well to
downstream of the meters
June 1st, 2015Marc L. Fischer ([email protected])
• Motivation and Overview– NG methane contribution as a CA climate pollutant
– Bottom-up estimates of natural gas (NG) methane emissions
• CALGEM-NG – Regional Top-down Study of SF Bay Area Methane
– Airborne Facility Scale Measurements
– Localized Mobile Plume Integration (MPI)
– Emissions from Residential Buildings
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Team AcknowledgementsLBNL: Seongeun Jeong, Toby Walpert
UC Davis: Stephen Conley, Ian Faloona
UCI: Tianyang Zhu, Don Blake
SJSU: Matt Llyod, Neil Larau, Craig Clements
Picarrro: Eric Crosson, Chris Rella
BAAQMD: David Fairley, Phil Martien, Saffet Tanrikulu
CEC: Guido Franco, Simone Brant
PG&E: François Rongere, Gerry Bong
UC Berkeley: Allen Goldstein, Abhinav Guha
NOAA-CCG: Arlyn Andrews , Laura Bianco, Ed Dlugokencky, Jim Wilczak, Steve Montzka, Ben Miller, Pieter Tans
CIT: Sally Newman, Debra Wunch, Paul Wennberg
UCR: Jingsong Zhang, Mixtli Campos
NASA Ames: Laura Iraci, Emma Yates, Matt Johnson
JPL: Riley Duren, Christian Frankenberg, Charles Miller
UCSD: Ray F. Weiss, Ralph Keeling, Peter Salameh
EarthNetworks: Christopher D. Sloop, Bob Marshall
CARB: Ying-Kuang Hsu, Abhilash Vijayan, Jorn Herner, Bart Croes, Vernon Hughes, Marc Vayssières, Richard Bode, Joseph Fischer, Jim Narady, and Webster Tassat, Mac McDougall, Ken Stroud
This work was supported by the California Energy Commission, Natural Gas Environmental Research Program
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Problem Overview• Natural gas provides 43% California’s fossil fuel energy
• Methane is a potent short lived climate pollutant– A 3% well-to-burner methane leak approximately equals climate
forcing from remaining 97% gas combusted to CO2 on 20 year timescale
– Pre-meter distribution and post-meter consumption leakage paths deserve attention
• CA and US now moving to control CH4 emissions
– Current inventories typically lower than measurements in facility or regional studies
– Likely ~ 10% California’s methane emissions from NG
• CEC survey project provides new look across CA natural gas infrastructure
Overview of Natural Gas System• Many sub-sectors
may contribute to total NG emissions
• Post-meter emissions previously neglected
• More complete representation captures emissions per energy delivered
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Courtesy G. Franco and S. Ziaja adapted from US-EPA
Bottom-up Natural Gas Inventories Vary
• Combine US-EPA emission factors and GIS activity data Production: Conventional and enhanced
recovery wells Transmission, compression, and storage Distribution 0.3% of regional
consumption (1st guess) Prior CALGEM-NG emissions (Jeong et
al., 2014) still lower in SoCAB than recent top-down (Peischl et al., 2013)
Resulting CALGEM-NG emissions likely 200-400 Gg CH4 yr-1
Livestock and landfills likely much larger in CA so NG 10-20% of total CA CH4
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CALGEM-NG Methane Flux (nmol m-2 s-1)
CALGEM-NG CH4 Collaboration
• Regional Emissions– Tower Collaborations
• Facilities Leakage– Aircraft Observations
• Localized Plumes– Mobile Plume Integration– Building Studies 0.1 °× 0.1 °
LBL & Picarro Plume UCD Airborne UCI VOC SJSU Lidar LBL Residential
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Estimating Regional NG Emissions
Total NG Methane
0.1 °× 0.1 °
• NG:Total CH4 emission ratio only large in urban/production areas
• Evaluate emissions in SF Bay Area
• Light alkane composition (ethane:methane) key for attribution
0.1 °× 0.1 °
nmol/m2/s
Regions
SoCAB
San JoaquinValley
NG CH4 Total CH4 NG:Total Ratio nmol/m2/s
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Bay Area Methane• Collaboration with
BAAQMD (Fairley et al., 2014, ES&T)
• Estimate CH4 emissions CH4:CO correlations + CO emission inventory– Total CH4 1.5 – 2.0 x
BAAQMD Inventory
– AQ focused sites likely biased toward CO emissions
– Likely NG significant urban contribution
• Future: include VOC tracers to quantify NG emissions from distribution
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1989-91
1993-95
1996-98
1999-2001
2002-2004
2005-07
2009-12
0
50
100
150
200
250
300
350
400
450
500 Napa
Fremont
San Jose
San Rafael
Pittsburg
Vallejo
Richmond
Concord
Redwood City
Santa Rosa
Livermore
San Francisco
Inventory ch4*
CH
4 em
issi
on
s (G
gC
H4/
year
)
Wind
Methane Plume
Airborne Studies of Point Sources Validated with Controlled Release Tests
Controlled PG&E methane and ethane release in natural gas
Release rate ~ 15 kg CH4 hr-1
Flight data estimates recover both methane and ethane to within 20%
Recover ethane:methane ratio to better than 10%
* note 0.1 Gg CH4 yr-1 = 11.4 kg CH4 hr-1
Courtesy Steven Conley
Wind
Bay Area NG Storage and Petroleum Refining
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Bottom-up estimates for average storage emissions 80 kg CH4 hr-1 (US- EPA)
Airborne measurements at four storage facilities (June, 2014 – May, 2015) Two sites non-detection, one site small ~
11 Kg CH4 hr-1
Five flight days at 4th site larger and variable 80 - 300 kg CH4 hr-1
C2H6:CH4 matches PG&E ( ~ 5% vol)
Initial measurements at three refineries (Feb-May, 2015) Large variation in emissions 30 - 250 kg
CH4 hr-1
and ethane:methane ratios 6-20%
San Joaquin Valley Production Flights April -June, 2014
Clear downwind enhancements of CH4 and ethane on both days
Emissions from example production field Flight data 14 +/- 5 Gg CH4 yr-1
CALGEM bottom-up 10 Gg CH4 yr-
1
Another larger field shows episodic emissions, apparently correlated with well completion
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Local Measurements: LBNL Mobile Plume Integration (MPI*) System
• Cross-wind integral of CH4 enhancement flux quantifies plume emissions– Sample inlets can be set to 4-8 m
above ground
– Anemometry of wind velocity
• Recent system developments– Tests at LBNL and PG&E facilities
– Better than 30% accuracy with 3 passes in most conditions
– Multi-analyzer system w/ 13CH4 allows NG attribution for strong plumes
* Patent Pending
Gas System CH4 Plume at 1, 2, 4 m agl
Wind direction
4 m2 m1 m
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Capped Gas Wells in Sacramento Delta
• Plan drive using CA Dept. Cons. well map data
• 1 day drive-by of 12 capped wells– Quantify one plume 130 +/- 40 sccm
(5 passes)– Detected 3 plumes 40-350 sccm (one
pass each)– Non-detect for 2 sites– 7 sites not downwind of public road
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Methane Plume
MPI System
CH4 Enhancement in vertical plane
Capped well
Bakersfield Distribution System Survey 80km of Bakersfield public
streets Detect 20 large leaks above
above elevated varying background
40% emissions found within 0.5 km of large distribution pipes
Plume integrations yield total emissions of 6.4 kg CH4 hr-1
Scaling by area suggests total emissions ~ 90 kg CH4 hr-1
Comparing with consumption suggests ~ 0.3% distribution leakage
Consistent with CALGEM-NG distribution estimate
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CH4 enhancements (green), distribution (orange) and transmission (blue) pipelines
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Residential Leakage
C0Q + E = Ci Q
E = Q (Ci - C0)
Ci
Ci
Outdoor CH4 C0
Air flow in
E leak
Measurements Depressurize house producing
controlled inflow of outdoor air Measure CH4 enhancement relative to
outdoor air 13CH4/12CH4 used to identify gas vs.
biological methane
Results from 10 SF Bay homes Average leak rate 7 +/- 2 sccm
equal ~ 0.16% of consumption
Indoor CH4 enhancements show NG 13CH4 signature
New CEC project underway to measure 50-75 homes across CA housing stock
Measured indoor (white) and outdoor (grey) methane during calibrated indoor leak (red)
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Combustion Appliance Leakage Methods
Mass balance gathering total exhaust stream as with building level test
Ratio of CH4:CO2 enhancements + fuel use yields emissions
Examples: tank-less water heaters, clothes driers, gas range Three tank-less water heaters emitted
80 - 300 sccm CH4
1 hr operation ~ equal 1 day of quiescent house leakage
Two clothes driers emitted ~ 10 sccm emissions in continuous operation
One gas range emitted ~ 5 sccm in continuous operation
Summary and Next Steps Work sponsored by CEC identifying key components
of natural gas CH4 emissions from CA Emissions from production and distribution sectors
uncertain and likely underestimated in state current inventories
Production emissions episodic -> continuous observation Distribution emissions diffuse -> NG tracers
Atmospheric measurements can quantify emissions reductions at multiple scales Need to identify critical gaps in mitigation activities
Energy systems, agriculture, waste management
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