"The CSIRO and Department of Environment are currently reviewing the way natural gas emissions are measured, estimated and reported": APPEA chief technical officer Rick Wilkinson. Photo: Glenn Hunt
Australia's coal seam gas industry has rejected a peer-reviewed report that suggests greenhouse gas emissions from drilling and fracking are 50 per cent worse than thought.
The Harvard University-led study found methane leaks from the US fossil fuel industry were far higher than official estimates.
The Australian Petroleum Production and Exploration Association (APPEA) said it had no implications for the local industry, which claims coal seam gas is far cleaner than coal.
The result, published in the US journal Proceedings of the National Academy of Sciences, contradicted a move by the US Environmental Protection Agency to cut its estimates of methane emissions from fossil fuel extraction and processing by 25 per cent to 30 per cent for 1990-2011.
''We find that [methane] data from across North America instead indicates the need for a much larger adjustment of the opposite sign,'' the report said.
Debate over the venting of methane during gas drilling has intensified as companies and countries estimate its global warming impact.
While gas often has lower greenhouse gas impact than coal, the benefit of switching fuels is undermined to the extent methane is emitted during extraction and processing.
Methane traps about 21 times as much heat as carbon dioxide, although it remains in the atmosphere for a shorter time.
APPEA chief technical officer Rick Wilkinson said the new results ''add to a growing body of data''.
He said the results compared with ''conflicting work'' from the University of Texas, published in the same journal in August, that found measurements of 190 onshore natural gas sites in the US showing methane emissions at completed wells were lower than estimated.
Estimates of emissions from Australia's rapidly expanding coal seam gas industry remain limited.
A 2012 study by researchers at the Southern Cross University found significant amounts of methane appeared to be leaking from the country's largest coal-seam field, near Condamine on Queensland's Western Downs.
Testing inside the Tara gasfield showed some greenhouse gas levels were three times higher than nearby districts.
Mr Wilkinson said the US study had focused on US shale gas developments, making ''its direct application to natural gas production in Australia limited''.
''In Australia, the industry reports and is responsible for all emissions associated with its activities,'' Mr Wilkinson said.
''The CSIRO and [federal] Department of Environment are currently reviewing the way natural gas emissions are measured, estimated and reported in a research project the industry supports.''
The latest US study estimated emissions in 2007-08, using measurements on the ground, in telecommunications towers and from aircraft. The study's authors are examining more recent data to take into account a boom in oil and gas drilling in the US in recent years.
Burning natural gas emits about half the carbon of coal but its climate benefits can be undercut by methane leaks at well sites and in transporting the fuel.