Methane emission quantification and reduction within the waste sector

Scheutz¹, A. M. Fredenslund, P. Kjeldsen

¹Department of Environmental and Resource Engineering, Building 115, Technical University of Denmark, 2800 Kgs, Lyngby, Denmark.

Methane – a potent greenhouse gas - is emitted from several different treatment plants in the waste sector such as landfills, anaerobic digestion, composting, and wastewater treatment. Emissions vary in time and space and are highly dynamic. The sources are often complex consisting of many different unit processes at the treatment plant e.g. wastewater treatment plants and cover a large area e.g. landfills. Emission can thus occur from local point sources, leakages or hotspots. As an example, investigations have shown that for landfills emission rates can vary up to seven orders of magnitude within a few meters distance and that 50-70% of the total emission comes from a minor area (<5%) of the landfill. Quantification of these fugitive emissions are challenging, however measurement methods to identify local point sources and to quantify whole plant emissions are key in mitigating these direct emissions and documenting future reduction targets.

A well-established, validated, measuring method is the tracer gas dispersion method (TDM) which can quantify methane emissions at the facility level. The method relies on continuous, controlled release of a gaseous tracer at the source combined with downwind measurements of concentration of target gas (e.g. methane) and tracer gas (often acetylene). This method is well-established, validated, and has been used to quantify fugitive methane emissions from various sources such as landfills, composting plants, biogas plants, oil and gas, etc. The method has been applied at several facilities to determine emission rates, emission factors and mitigation efficiencies.

Three application cases will be presented:

• A landfill study focusing on determination of gas collection efficiencies and fulfillment of future reduction targets carried out at 23 Danish landfills.
• A landfill study presenting methane mitigation efficiencies of a new biocover technology implemented at 22 sites
• A biogas study quantifying methane emissions and losses at 69 Danish biogas plants

Combined the cases will illustrate how measurement can be used to determine emission rates, set emission reduction targets and document fulfillment.

References

Fredenslund, A.M., Gudmundsson, E., Falk, J.M., Scheutz, C., 2023. The Danish national effort to minimise methane emissions from biogas plants. Waste Management, 157, 15, 321-329.

Duan, Z., Kjeldsen, P., Scheutz, C. 2022. Efficiency of gas collection systems at Danish landfills and implications for regulations. Waste Management, 139, 269-278.