Under fire … debate gathers heat on how clean it is. Photo: Glenn Hunt

GREENHOUSE gases are leaking from some US gas drilling sites at up to double the expected amounts, raising questions over the use of gas as a low-emissions fuel, according to researchers from the US National Oceanic and Atmospheric Administration.

The report has implications for Australia’s coal seam gas industry, which is marketing itself as a source of clean energy.

The industry body, the Australian Petroleum Production and Exploration Association, said that, regardless of how coal seam gas emissions were calculated, they would all ultimately be accounted for under the federal government’s carbon price plan.

The US researchers calculated that about 4 per cent of the gas being extracted at a Colorado shale gas field was escaping as methane, a highly potent heat-trapping gas that is accelerating global warming. The gas industry in the US has argued that not more than 2 per cent of the gas brought up by drilling escapes into the atmosphere.

The National Oceanic and Atmospheric Administration scientists stumbled upon the findings during an air monitoring experiment, when unusual levels of methane were detected and traced back to the gasfield.

”Our analysis suggests that the emissions of the [methane] we measured are most likely underestimated in current inventories and that the uncertainties attached to these estimates can be as high as a factor of two,” said their report, which is published in the peer-reviewed Journal of Geophysical Research.

Small extra amounts of methane can make significant differences to climate change because it is up to 100 times more potent than carbon dioxide.

It also has a shorter life span than carbon dioxide, meaning that most of the warming effect of gas released today is concentrated into the next two decades, a crucial period for avoiding future tipping points into dangerously rapid climate change.

The study comes in the middle of a global boom in gas extraction and fracking, or hydraulic fracturing, that has resulted in an increase in the use of gas fuel in many countries.

The Greens seized on the US research to argue that similar studies should be done in Australia to find out if greenhouse emissions from the coal seam gas industry were as low as the industry has said.

“The coal seam gas industry’s claims to be better for the climate than coal are increasingly being called into question by the evidence,” Senator Christine Milne said.

“Given these results from field measurements in the USA, it’s no wonder the industry in Queensland, NSW and across Australia is fighting hard to stop credible measurements of its performance being done.”

The chief operating officer of the Australian Petroleum Production and Exploration Association, Rick Wilkinson, said in a statement that ”irrespective of the credibility or accuracy of the report in question, the important thing to note is that unlike the American industry, Australian gas producers will very shortly have a carbon pricing scheme that requires they pay for all emissions and provides an even greater incentive to reduce emissions.”

The Department of Climate Change and Energy Efficiency has previously told the Herald that it monitors scientific developments in the measurement of greenhouse gas emissions and would update its accounting methods if required.