Methane levels within urban average at Macarthur, study says
Wednesday, February 05, 2014
Methane concentrations in the Macarthur region where natural coal seam gas is produced are in line with averages for urban areas without coal seam gas production, a specialist scientific study has found.
The AGL Fugitive Methane Emissions Monitoring Program - the first of its kind in NSW - was conducted by air quality specialists Pacific Environment using the Picarro, one of the world's most sensitive, state-of-the-art instruments for this type of testing.
Australia's national science agency, the CSIRO, reviewed an early draft of the report and provided comments.
Twenty-five locations in the Macarthur region were monitored weekly, at different times of the day and night, with 75 hours of measurements for analysis and reporting.
During the 12-week monitoring program the average methane concentration was 2.1ppm (parts per million). This is in line with methane concentrations measured in urban areas commonly ranging between 1.8ppm and 3.0ppm.
These results are lower than readings measured inside a house in the local area:
One metre from an outside gas hot water system = 9-10ppm;
50 centimetres from a domestic gas heater vent = 2.4ppm
50 centimetres from a domestic gas stove cooker = 10.2ppm
Mike Moraza, AGL's Group General Manager Upstream Gas, said the study was developed and conducted in response to community concerns.
"The community has told us they needed more information about fugitive methane emissions, and so AGL voluntarily invested in a research study that goes beyond our regulatory requirements," Mr Moraza said.
"We involved the community in determining the monitoring sites and at their request increased the number of sites from 17 to 25 in order to get readings from background areas and locations within the Camden Gas Project.
"We tested methane emissions in local parks, near schools and where people in the Macarthur region live and breathe the air.
"The results show that methane concentrations in the Macarthur region are consistent with urban averages, which should reassure the community that it is safe to live and work side by side AGL's activities."
Pacific Environment's Damon Roddis said the testing was thorough and used state-of-the art equipment.
"We are an organisation of air quality specialists and have been monitoring the atmosphere and fugitive air emissions for decades," Mr Roddis said.
"The results obtained from the AGL monitoring study show that when other local sources are removed from the data, there is no significant difference between the methane concentrations experienced in the Macarthur region and similar locations where no coal seam gas activities are occurring.
"We used one of the best pieces of monitoring equipment in the world for this type of measurement and stand by the conclusions of the study."
Methane (CH4): Methane is a naturally occurring gas that is present in the atmosphere in low concentrations. It's non-toxic and has no known health effects. Some natural sources of methane are wetlands, coal seams and termite activity. Man-made sources include agricultural operations, landfill and wastewater treatment, rice paddies and oil and gas production. The gas from the Camden Gas Project is 96% methane (with the remaining 4% being mainly carbon dioxide and nitrogen), which is not toxic or dangerous to human health and why the research study measured methane.
Global average methane concentration: is 1.8 parts per million (ppm). (WMO, 2013)
Urban average methane concentrations: commonly range between 1.8ppm and 3.0ppm (Lowry et al. 2001).
Fugitive emissions: refer to unintended or irregular gas releases that are not captured or controlled through an emission point such as an exhaust stack or vent.
The Fugitive Emissions Monitoring Program: ran for 12 weeks from 29 April 2013 to 17 July 2013.
Picarro G-2201-i Cavity Ring Down Spectrometer: is one of the best air quality measurement and analysis instruments available in the world. Its monitoring system has been configured for field monitoring, measuring methane concentration and isotopic ratios for methane, as well as wind speed, wind direction and GPS coordinates.
AGL's Camden Gas Project: has been producing gas for the Sydney region since 2001. It currently supplies about five percent of NSWs' gas needs. The project includes 144 gas wells - with 96 currently producing gas - 100 kilometres of low-pressure underground gas gathering lines and the Rosalind Park Gas Plant.