Fugitive methane emissions – an update

Key points:

• Fugitive emissions are losses, leaks and other releases of methane to the atmosphere that are associated with industries producing natural gas, oil and coal. They also include CO2 emissions associated with flaring of excess gas to the atmosphere.
• In Australia, fugitive emissions from oil and gas production are estimated to account for about 6.0% of greenhouse gas emissions.
• To accurately measure fugitive emissions, natural background biological and geological sources must be separated from human sources. CSIRO studies aim to separate these sources.
• CSIRO has a range of research programs underway in Queensland, New South Wales, Western Australia and the Northern Territory using measuring and monitoring techniques, life-cycle analysis methods and industry activity data to provide accurate and comprehensive estimates of natural and and fugitive emissions in Australia.
• A recent CSIRO study on GHG emissions from a CSG-LNG company in Queensland estimated total GHG direct and indirect emissions (scope 1 and scope 2) of the production chain of about 5 Mt CO2-e/year. These GHG emissions amounted to 1.4 % of CSG production (576 PJ). A further 40 Mt CO2-e/year were generated by shipping LNG, regasification and combustion in Asia.
• Another CSIRO study using ‘top down’ atmospheric inversion of methane concentration data in the central Surat Basin coupled with a ‘bottom-up’ inventory of methane sources for the same region suggested that fugitive methane emissions from upstream gas production infrastructure is less than 0.5% of CSG production (576 PJ).
• This study also found the largest contribution to total methane emissions in this region was cattle grazing (54%), followed by feedlots (24%) and CSG processing (8%) (Luhar et al., 2018).Fugitive emissions are losses, leaks and other releases of methane to the atmosphere that are associated with industries producing natural gas, oil and coal.
• The median fugitive emissions from measurements of CSG wells in Queensland and NSW is less than 1kg/day with 1% of wells releasing 63 kg/day. Well completion and work-over measurements show releases of 200 kg/day and 20 t/day, respectively. Measurements made at a CSG water treatment plant were between 18 and 32 kg/day and from a CSG compression plant, emissions were 780 kg/day. To put these measurements into context, methane fluxes measured from an urban sewerage treatment plant were 45 kg/day, a medium sized waste landfill were 400 kg/day and from a cattle feed lot were 2,600 kg/day.

Read more about the ‘Whole of life cycle greenhouse gas assessment’ project here.