The year-long study by the CSIRO’s gas research branch, GISERA, aimed to establish a baseline for methane emissions in the Narrabri region, which will be used to measure any increases should the Santos coal seam gas project go ahead.

The study found that the ambient methane concentrations are mostly similar to background concentrations observed in undisturbed areas, while methane emissions from the CSG wells were consistent with similar studies conducted in the Queensland gas fields.

GISERA director Damien Barrett said the study provide the community with both numbers and context.

“The 72 wells in the Pilliga create under 300 millilitres of methane per day, which is less than a herd of under 2000 head of cattle,” Dr Barrett said.

“A medium-sized landfill produces about 50 per cent more than those wells.”

Lock the Gate’s NSW coordinator, Georgina Woods, said the study was “better late than never”.

“It would have been great to have proper measurements before the mobilisation of methane in the Pilliga – there’s been activity there for about 10 years,” Ms Woods said. 

“In Queensland, people have found [the methane] really does come up anywhere. The gas company obviously wants it to go up the drilling line, but in a lot of instances it simply comes to the surface through the soil or rivers.”

A spokesperson for Australian gas industry body APPEA, said the organisation welcomed the research.

“The onshore gas industry across Australia is required to measure, report and account for all of its greenhouse gas emissions,” they said.

“The existence of other sources of methane, which may not be measured, can make ongoing measurement more difficult.

“This baseline emissions data from the CSIRO will be important should NSW choose to develop its gas resources and benefit from more jobs, lower power prices, higher economic growth, and lower greenhouse emissions.”

Ms Woods said a study by the University of Melbourne showed migratory methane emissions from CSG fields had the potential to blow Australia’s Paris Agreement obligations “without even knowing it”.

“It was something a lot of people raised their submissions about the Santos project,” she said.

“We would like an indication from both the state and federal government that they will consider the full life cycle of the project’s emissions in the context of our Paris commitments.”