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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 (mlfischer@lbl.gov)

• 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

QQ

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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