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Methane Emissions in the Natural Gas Life Cycle and Implications for Power Generation: Update on Emission Studies Presentation for the Western Interstate Energy Board March 17, 2015 Tom Curry tcurry@mjbradley.com M.J. Bradley & Associates

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

Presentation for the Western Interstate Energy Board March 17, 2015

Methane Emissions in the Natural Gas Life Cycle and Implications for Power Generation: Update on Emission Studies

Tom Curry tcurry@mjbradley.com

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

Key Takeaways

Recent bottom-up studies of emissions from natural gas systems have reinforced the idea
f a “fat-tail” issue where a small percentage of sources are responsible for a large

percentage of emissions

EPA continues to refine the GHG Inventory to reflect reported data and recent studies,

while source contributions have changed, total emission estimates have remained fairly steady across recent inventories

Recent top-down studies highlight significant regional variability which could contribute to

the disparity between bottom-up approaches and earlier top-down studies

Natural gas combined cycle power plants have about half the life cycle greenhouse gas

emissions of coal-fired power plants

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

Estimating Fugitive and Vented Methane Emissions

Bottom-up Studies

Direct measurements of emissions at the

device or facility level are used to develop emission factors

Inventories based on emission factors and

activity data

Life cycle assessments based on

inventories and measurements

Top-down Studies

Measurements of emissions at facility to

national scales, typically take at a location remote from individual pieces of equipment

Photo Source: CIRES/NOAA (http://cires.colorado.edu/news/press/2013/methaneleaks.html) Photo Source: EPA Gas STAR (http://www.epa.gov/gasstar/documents/workshops/buenosaires-2008/dim.pdf)

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

NOAA-led Top-down Methane Measurement Studies

Uintah Upper Green Valley Denver- Julesburg Fayetteville Marcellus Bakken Haynesville Eagle Ford Study Completed Study Planned

Source: EIA, MJB&A Analysis

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

Top-down Study Estimated Emission Rates

2 4 6 8 10 12 Denver-Julesburg (2008) Denver-Julesburg (2012) Uinta (2012) Fayetteville (2013) Haynesville (2013) Marcellus (2013) Published Pre-2015 Published 2015 Emission Rate (%)

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

1.8 2.1 2.5 7.6 20 18 5 10 15 20 25 2 4 6 8 10 12 Denver-Julesburg (2008) Denver-Julesburg (2012) Uinta (2012) Fayetteville (2013) Haynesville (2013) Marcellus (2013)

Basin Emission and Production Rates

Emission Rate (%) Production Rate (107 cubic meters/day) Published Pre-2015 Published 2015

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

Natural Gas System Emission Sources by Segment

Production and Gathering Processing Transmission and Storage 2014 EPA GHG Inventory Implied 2012 Methane Emissions Rate (CH4/NG Produced): 1.18%

0.4% 0.2% 0.4% Million metric tons CH4

Source: MJB&A analysis, EPA 2014 GHG Inventory, EIA Total U.S. Gross Natural Gas Withdrawals

Methane Emissions Rate: 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0

Distribution

0.2% 0.0 0.5 1.0 1.5 2.0 2.5 3.0

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

Continued Progress on Bottom-Up Studies

Segment Component/Activity Direct Emissions Measurements Scaled to National Emissions Notes Production & Gathering Well completions and workovers

 

Allen et al. Phase I Pumps and other equipment leaks

 

Allen et al. Phase I Pneumatic controllers

 

Allen et al. Phase I & II Liquids Unloading

 

Allen et al. Phase I & II Gathering facilities



National estimate comparison in review Processing Processing plants



National estimate comparison in review Transmission & Storage Compressors



National estimate comparison in review Distribution Distribution networks City mapping data released, direct measurements forthcoming

 = Study published

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

Consistent Themes from Bottom-Up Studies

Emission factors used by EPA and others should be updated
Some should be adjusted up, others down
Despite changes in specific emission factors, overall inventory appears to be

consistent with released studies

Site-level emission rates are skewed, with a small number of sources contributing

a large percentage of overall emissions

Findings of “superemitters” across the studies
Evidence of regional variability with sources emitting at different rates in different

regions

Accuracy of EPA’s GHG Reporting Program could be improved by increasing direct

measurement

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

Recent Production Studies Compared to Inventory

Emissions Source UT Austin Studies 2014 GHG Inventory 2015 GHG Inventory (Draft) Flowback from Hydraulically Fractured Wells 24 217 138 Chemical Pumps 73 65 63 Pneumatic Devices 600 334 653 Liquids Unloading 270 274 267 Other Sources 1,218 1,102 991 Total EPA Production Emissions 2,185 1,992 2,112 Leak Rate (CH4/ NG produced) 0.38% 0.35% 0.37%

2012 Production Emissions Across Inventories (thousand metric tons CH4)

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

Natural Gas System Emission Sources by Segment

Production and Gathering Processing Transmission and Storage 2014 EPA GHG Inventory Implied 2012 Methane Emissions Rate (CH4/NG Produced): 1.18%

Million metric tons CH4

Source: MJB&A analysis, EPA 2014 GHG Inventory, EIA Total U.S. Gross Natural Gas Withdrawals

Distribution 2015 EPA GHG Inventory Implied 2012 Methane Emissions Rate (CH4/NG Produced): 1.20%

0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0

2015 Draft

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

Coal

Fuel (Combustion Technology)

lb CO2e/ MWh

MJB&A Life Cycle Assessment

Upstream fugitive and vented CH4 Other Upstream GHGs CO2 from electricity generation NGCC

Estimated Life Cycle Emissions for Natural Gas- and Coal- based Electricity Generation (100-year GWP)

GWP=34; “Natural Gas, 2014 Inv” based on 2014 EPA GHG Inventory less distribution segment emissions.

999 2331 500 1000 1500 2000 2500 Natural Gas, 2015 Inv (NGCC) Coal (Fleet Average Boiler)

Assumed Combustion Efficiency:

NGCC: 51%
Avg Coal: 34%

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0% 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% 11% 12% 13% 14% 15% 16%

lb CO2e/ MWh

Life Cycle Emissions at Different Emission Rates

100-year GWP

Avg Coal: 2331 lb CO2e/MWh Upstream fugitive and vented CH4 Other Upstream GHGs CO2 from electricity generation NGCC Avg Coal Boiler Total Emissions

Estimated Life Cycle Emissions for Natural Gas- and Coal-based Electricity Generation

(GWP = 34) Difference between NGCC and Coal

Vented and Fugitive Methane Rate for Natural Gas (production through transmission)

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0% 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% 11% 12% 13% 14% 15% 16%

lb CO2e/ MWh

Life Cycle Emissions at Different Emission Rates

100-year GWP

Avg Coal: 2331 lb CO2e/MWh (34%) Upstream fugitive and vented CH4 Other Upstream GHGs CO2 from electricity generation NGCC Technology (Efficiency) Avg Coal Boiler (34%)

Estimated Life Cycle Emissions for Natural Gas- and Coal-based Electricity Generation

(GWP = 34)

Vented and Fugitive Methane Rate for Natural Gas (production through transmission)

SC Coal: 2019 lb CO2e/MWh (39%) Supercritical Coal Boiler (39%) Avg NGCC (51%)

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0% 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% 11% 12% 13% 14% 15% 16%

lb CO2e/ MWh

Life Cycle Emissions at Different Emission Rates

100-year GWP (Comparison of Power Plant Efficiency)

Avg Coal Range for NGCC (45% to 60%) Avg Coal Boiler (34%)

Estimated Life Cycle Emissions for Natural Gas- and Coal-based Electricity Generation

(GWP = 34)

Vented and Fugitive Methane Rate for Natural Gas (production through transmission)

SC Coal Supercritical Coal Boiler (39%) Avg NGCC (51%) Range for Simple Cycle (30% to 40%) Technology (Efficiency)

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M.J. Bradley & Associates LLC (978) 369 5533 / www.mjbradley.com

Ongoing Research and Emerging Issues

Upcoming bottom-up and top-down studies will provide better understanding of

emissions from individual sources and gas production regions

Better account for regional emissions variations and activity data
Airborne emissions measurements over western U.S. shale gas and tight oil basin
Will also measure emissions from surface coalmines, oil pipelines, coal and gas

power plants, and biofuel refineries

Updating Inventory methodologies
Regional data from direct measurements to play larger role in estimating national

emissions

Revisions to the GHG Reporting Program
Apportionment studies assigning methane to natural gas production or petroleum