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 LLC (978) 369 5533 / www.mjbradley.com
Key Takeaways Recent bottom-up studies of emissions from natural gas systems have reinforced the idea of 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 M.J. Bradley & Associates LLC 2 (978) 369 5533 / www.mjbradley.com
Estimating Fugitive and Vented Methane Emissions Top-down Studies • Measurements of emissions at facility to national scales, typically take at a location remote from individual pieces of equipment 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 Photo Source: EPA Gas STAR Photo Source: CIRES/NOAA ( http://www.epa.gov/gasstar/documents/workshops/buenosaires-2008/dim.pdf ) (http://cires.colorado.edu/news/press/2013/methaneleaks.html) M.J. Bradley & Associates LLC 3 (978) 369 5533 / www.mjbradley.com
NOAA-led Top-down Methane Measurement Studies Bakken Upper Green Valley Denver- Julesburg Uintah Marcellus Fayetteville Haynesville Eagle Ford Study Completed Study Planned Source: EIA, MJB&A Analysis M.J. Bradley & Associates LLC 4 (978) 369 5533 / www.mjbradley.com
Top-down Study Estimated Emission Rates Published Pre-2015 Published 2015 Emission Rate (%) 12 10 8 6 4 2 0 Denver-Julesburg Denver-Julesburg Uinta (2012) Fayetteville Haynesville Marcellus (2013) (2008) (2012) (2013) (2013) M.J. Bradley & Associates LLC 5 (978) 369 5533 / www.mjbradley.com
Basin Emission and Production Rates Emission Rate (%) Production Rate (10 7 cubic meters/day) Published Pre-2015 Published 2015 12 25 20 10 20 18 8 15 6 10 7.6 4 5 2 2.5 2.1 1.8 0 0 Denver-Julesburg Denver-Julesburg Uinta (2012) Fayetteville Haynesville Marcellus (2013) (2008) (2012) (2013) (2013) M.J. Bradley & Associates LLC 6 (978) 369 5533 / www.mjbradley.com
Natural Gas System Emission Sources by Segment 2014 EPA GHG Inventory Implied 2012 Methane Emissions Rate (CH 4 /NG Produced): 1.18% Methane 0.4% 0.2% 0.4% 0.2% Emissions Rate: Production and Transmission and Processing Distribution Gathering Storage Million metric tons CH 4 3.0 3.0 3.0 3.0 2.5 2.5 2.5 2.5 2.0 2.0 2.0 2.0 1.5 1.5 1.5 1.5 1.0 1.0 1.0 1.0 0.5 0.5 0.5 0.5 0.0 0.0 0.0 0.0 Source: MJB&A analysis, EPA 2014 GHG Inventory, EIA Total U.S. Gross Natural Gas Withdrawals M.J. Bradley & Associates LLC 7 (978) 369 5533 / www.mjbradley.com
Continued Progress on Bottom-Up Studies Segment Component/Activity Direct Scaled to Notes Emissions National Measurements Emissions Well completions and Allen et al. Phase I workovers Pumps and other Allen et al. Phase I equipment leaks Pneumatic controllers Allen et al. Phase I & II Production & Gathering Liquids Unloading Allen et al. Phase I & II Gathering facilities National estimate comparison in review Processing Processing plants National estimate comparison in review Transmission & Compressors National estimate comparison in Storage review Distribution Distribution networks City mapping data released, direct measurements forthcoming = Study published M.J. Bradley & Associates LLC 8 (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 M.J. Bradley & Associates LLC 9 (978) 369 5533 / www.mjbradley.com
Recent Production Studies Compared to Inventory 2012 Production Emissions Across Inventories (thousand metric tons CH 4 ) Emissions Source UT Austin Studies 2014 GHG Inventory 2015 GHG Inventory (Draft) Flowback from 24 217 138 Hydraulically Fractured Wells 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 2,185 1,992 2,112 Emissions Leak Rate (CH 4 / NG 0.38% 0.35% 0.37% produced) M.J. Bradley & Associates LLC 10 (978) 369 5533 / www.mjbradley.com
Natural Gas System Emission Sources by Segment 2014 EPA GHG Inventory Implied 2012 Methane Emissions Rate (CH 4 /NG Produced): 1.18% 2015 EPA GHG Inventory Implied 2012 Methane Emissions Rate (CH 4 /NG Produced): 1.20% Production and Transmission and Processing Distribution Gathering Storage Million metric tons CH 4 3.0 3.0 3.0 3.0 2015 Draft 2.5 2.5 2.5 2.5 2.0 2.0 2.0 2.0 1.5 1.5 1.5 1.5 1.0 1.0 1.0 1.0 0.5 0.5 0.5 0.5 0.0 0.0 0.0 0.0 Source: MJB&A analysis, EPA 2014 GHG Inventory, EIA Total U.S. Gross Natural Gas Withdrawals M.J. Bradley & Associates LLC 11 (978) 369 5533 / www.mjbradley.com
MJB&A Life Cycle Assessment Estimated Life Cycle Emissions for Natural Gas- and Coal- based Electricity Generation (100-year GWP) 2500 lb CO 2 e/ 2331 MWh NGCC Coal Upstream 2000 fugitive and vented CH 4 Other 1500 Upstream GHGs 999 CO 2 from 1000 electricity generation 500 Assumed Combustion Efficiency: • NGCC: 51% 0 • Natural Gas, 2015 Inv Coal Avg Coal: 34% (NGCC) (Fleet Average Boiler) Fuel (Combustion Technology) GWP=34; “Natural Gas, 2014 Inv ” based on 2014 EPA GHG Inventory less distribution segment emissions. M.J. Bradley & Associates LLC 12 (978) 369 5533 / www.mjbradley.com
Life Cycle Emissions at Different Emission Rates 100-year GWP Estimated Life Cycle Emissions for Natural Gas- and Coal-based Electricity Generation (GWP = 34) lb CO 2 e/ 5000 MWh 4500 Avg Coal Boiler 4000 Total Emissions 3500 NGCC 3000 Upstream 2500 fugitive and Avg Coal: 2331 lb CO 2 e/MWh vented CH 4 2000 Difference between Other NGCC and Coal Upstream 1500 GHGs 1000 CO 2 from electricity generation 500 0 0% 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% 11% 12% 13% 14% 15% 16% Vented and Fugitive Methane Rate for Natural Gas (production through transmission) M.J. Bradley & Associates LLC 13 (978) 369 5533 / www.mjbradley.com
Life Cycle Emissions at Different Emission Rates 100-year GWP Estimated Life Cycle Emissions for Natural Gas- and Coal-based Electricity Generation Technology (GWP = 34) lb CO 2 e/ 5000 (Efficiency) MWh Avg Coal 4500 Boiler (34%) Supercritical 4000 Coal Boiler (39%) 3500 Avg NGCC (51%) 3000 2500 Avg Coal: 2331 lb CO 2 e/MWh (34%) NGCC SC Coal: 2019 lb CO 2 e/MWh (39%) Upstream 2000 fugitive and vented CH 4 1500 Other Upstream 1000 GHGs 500 CO 2 from electricity 0 generation 0% 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% 11% 12% 13% 14% 15% 16% Vented and Fugitive Methane Rate for Natural Gas (production through transmission) M.J. Bradley & Associates LLC 14 (978) 369 5533 / www.mjbradley.com
Life Cycle Emissions at Different Emission Rates 100-year GWP (Comparison of Power Plant Efficiency) Estimated Life Cycle Emissions for Natural Gas- and Coal-based Electricity Generation Technology (GWP = 34) lb CO 2 e/ 5000 (Efficiency) MWh Avg Coal 4500 Boiler (34%) Supercritical 4000 Coal Boiler (39%) 3500 Avg NGCC (51%) 3000 2500 Avg Coal Range for NGCC SC Coal 2000 (45% to 60%) Range for 1500 Simple Cycle (30% to 40%) 1000 500 0 0% 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% 11% 12% 13% 14% 15% 16% Vented and Fugitive Methane Rate for Natural Gas (production through transmission) M.J. Bradley & Associates LLC 15 (978) 369 5533 / www.mjbradley.com
Recommend
More recommend
