State of Methane Emission and Oxidation Research

1. State of Methane Emission and Oxidation Research Stephanie C. Bolyard, PhD Research and Scholarships Program Manager

2. Landfill Methane Production CO2 CH4 Recovery CH4 Emitted CH4 oxidation Gas well CH4 Production CH4 Recovery + CH4 oxidation + CH4 Emitted

3. Methane Emissions and Oxidation • Understanding methane emissions and oxidation if challenging due to operational limitations, monitoring challenges, weather, and site specific conditions. • Quantifying emissions is important to meet regulatory requirements.

4. Landfill Gas Research Focus • Emissions quantification • Accurate/easy field measurement methods • Methane oxidation • Accurate data under varying field conditions • Collection efficiency • Data gaps • Accurate measurement

5. Measuring Fugitive Emissions GRANTEE: SCS Engineers (in partnership with Waste Management and Veolia NA)

6. Measurement of Methane Emissions • Vertical Radial Plume Mapping • Tunable diode laser/FTIR/Cavity Ringdown Spectroscopy (newer, emerging methods) • Differential Absorption LiDAR

7. Measurement of Methane Emissions • Tracer Methods • Micrometeorological Eddy-Covariance method • Flux Chamber

8. Landfill Fugitive Emissions Study • Tracer gas and DiAL methods appear to be the most promising approaches for landfill fugitive methane measurement • Study has re-defined EPAs perspective on measuring fugitive emissions • Help industry improve gas collection efficiency, reduce emissions, refine carbon footprint estimates

9. Porosity Effects on CH4 Oxidation GRANTEE: Florida State University (Jeff Chanton)

10. Porosity effects on CH4oxidation (FSU) • At the time of this research the guidelines assume landfill cover soils oxidize 10% of CH4 transported through cover • Hesitant to embrace recent work showing higher oxidation • Too limited to be representative of most landfills • Oxidation highly dependent on flow • Objectives of this study: • Evaluate CH4 oxidation across multiple sites • Effect of gas flow 90 % 10 % 100 %

11. Porosity Effects on CH4 Oxidation 28-43% (mean) 21-40% (median) Suggested value = 30% Theoretical Max. Oxid. (1 to 1 line) In reality, a single number is too simple. % Oxidation depends on the CH4 loading rate to the cover CH4 oxidation rate Max rate CH4 loading to cover

12. Porosity Effects on CH4Oxidation • The oxidation rate results obtained from the 60-cm-thick cover simulations are essentially the same as the ones obtained from the 30-cm simulations. • Results showed that the thickness of the cover does not change the methane oxidizing capacity of the cover because in does not change the amount of methane that can be oxidized by a cover.

13. Landfill Emissions and Methane Oxidation: Field-Scale Test Sections Experiment GRANTEES: Florida State University (Abichou and Chanton)

14. EPA Rule on Methane Oxidation • EREF data and literature values were used to issue a new rule on methane oxidation • Methodology is based on the relation between methane loading to landfill covers and methane oxidation described by EREF data • Site specific methane oxidation that is dependent on methane flux: • 0% • 10% • 25%, or • 35%

15. Research Objectives • Assess field-scale methane oxidation using large-scale test pads with interim landfill cover soils • Less than 24 inches thick • Different methane loading flux conditions • Extended period of time to assess the variation due to climate

16. Test Pads in Oregon

17. Results Test Pad 2 6’’ local soil 12’’ compost

18. Oxidation during Monitoring Duration Mass balance shows that higher methane oxidation is possible in soil less than 24 inches

19. Accuracy of Whole-Landfill Methane Emissions Estimates with Tracer Dilution Method GRANTEES: University of Delaware and University of California, Berkeley (Imhoff and Chow)

20. Research Focus and Questions • Field studies in flat terrain validated tracer dilution method for point CH4 sources • Measurement errors for CH4 release from landfills • Transect distance and orientation • Vehicle speed • Misalignment of tracer with CH4 • Effect to topography • Address Questions with Wind Modeling at a landfill in Delaware • Emission measurements and wind data

21. Key Findings Tracer dilution method (TDM) Guidelines • Center tracer in high CH4 emission regions • Center horizontally • Center vertically • Make measurements downwind as far as possible • Road orientation and vehicle speed not significant source of error • Measurement errors at the studied landfill was ~ 30% or less.

22. Factors Affecting CH4 Emissions TDM measurements typically 2‐6 hours • To obtain annual emissions estimates, models needed that account for changing factors

23. Conclusions Fugitive Emissions • Tracer gas and DiAL methods appear to be the most promising approaches for landfill fugitive methane measurement Porosity Effects on CH4 Oxidation • Thickness of the cover does not change the methane oxidizing capacity of the cover Landfill Emissions and Methane Oxidation • Mass balance shows that higher methane oxidation is possible in soil less than 24 inches Whole-Landfill Methane Emissions • Dependency of CH4 emissions on wind speed suggests that care should be exercised in extrapolating whole-landfill emissions measurements made under particular wind conditions to emissions under different atmospheric conditions.

24. Questions Stephanie C. Bolyard, PhD sbolyard@erefdn.org

25. Introduction to EREF • Non-lobbying, non-profit charity • Began in 1992 • Mission: To fund and direct: • scientific research, and • educational initiatives for sustainable waste management practices to benefit industry participants and the communities they serve.

26. Methane Oxidation Measurements • Stable carbon (δ13C) and hydrogen (δ2H) isotopes • Mass balance and kinetic approaches Green, R. “Project Review: Landfill Emissions and Methane Oxidation: Field-Scale Test Sections Experiment” April 21, 2017