Quantification of Methane Emissions by Surface Mass Balance Method

This thesis presents a surface mass balance method as a cost-effective top-down technique to conveniently validate the bottom-up inventories. Mobile methane measurements were performed for two large landfills, Keele Valley Landfill and Greenlane Landfill and the city of Sarnia which included petrochemical industries and residential areas by employing a Cavity Ringdown Spectrometer (CRDS) mounted in a vehicle to capture downwind enhancements of methane. Methane emission from the Greenlane landfill was estimated to be 3300 ± 730 kg h-1 by a mass balance approach. An estimation by a gaussian dispersion model provided a similar emission rate of 3320 ± 250 kg h-1. The regression analysis of the mixing ratios of CO2 and CH4 showed positive correlation with an average molar ratio of 0.99 ± 0.04 mole mole-1 which was used to estimate CO2 emission to be 7600 ± 1700 kg h-1. The city of Sarnia including its industrial complex and residential areas showed a total methane emission rate of 2450 ± 560 kg h-1. It is estimated the city emits 21.5 ± 4.9 kt CH4 annually accounting for 45% of Ontario’s oil and gas methane emission. These estimated source rates from facilities were consistently 9-10 times greater than the GHGRP estimates. The discrepancies confirmed in the study emphasizes that it is significant to reconcile top-down measurements with the bottom-up inventories to provide a more accurate understanding of methane sources and sinks in Canada.