Methane leaking from coal seam gas field, testing shows
Vast amounts of methane appear to be leaking undetected from Australia’s biggest coal seam gas field, according to world-first research that undercuts claims by the gas industry.
Testing inside the Tara gas field, near Condamine on Queensland’s Western Downs, found some greenhouse gas levels over three times higher than nearby districts, according to the study by researchers at Southern Cross University.
The study has potential national consequences because last week’s energy white paper forecast a massive expansion of Australian coal seam gas drilling, and called for environmental objections to be removed to make large-scale gas extraction easier
Methane, carbon dioxide and other gases appear to be leaking up through the soil and bubbling up through rivers at an astonishing rate, the researchers said.
“The concentrations here are higher than any measured in gas fields anywhere else that I can think of, including in Russia,” said Damien Maher, a biochemist who helped conduct the tests. “The extent of these enriched concentrations is significant.”
The study has potential national consequences because last week’s energy white paper forecast a massive expansion of Australian coal seam gas drilling, and called for environmental objections to be removed to make large-scale gas extraction easier. In NSW, the Planning Assessment Commission is currently considering a proposal by AGL to drill 66 new coal seam gas wells in western Sydney.
The Australian Petroleum Production and Exploration Association, the leading industry, attacked the research, saying it was “premature and questionable”.
The coal seam gas industry has previously maintained that gas leakage in Australia is “negligible”, and the default assumption has been that about 0.12 per cent of gas leaks out of wells during production. Uncontrolled leaks up through rock fissures and soil, of the type measured by the Southern Cross University team, were assumed to be nil, and are unaccounted for under the federal emissions trading scheme.
The researchers drove back and forth on public roads through the gas fields at Tara, taking measurements every second via a cavity ring down spectrometer – the only instrument of its type in Australia. It enabled them to take thousands of real-time readings of several gases in the air, and accurately pinpoint them with a global positioning system.
“Everything we’re finding shows that something major is happening and we need to look deeper into the problem,” said Isaac Santos, a senior lecturer in biochemistry at Southern Cross University, who worked on the study with Dr Maher.
“I think what it shows is we have to go through all gas fields, and potential gas fields, and take measurements, so we have baseline data to work from.”
Inside the gas field, methane was measured at up to 6.89 parts per million, compared to an average background level outside the gas field of about two parts per million.
Carbon dioxide levels inside the gas field were measured at up 541 parts per million, compared to 423 parts per million outside.
The team also took samples of airborne methane from major wetlands and high-density cattle operations near Casino in northern NSW, using the same equipment.
“The concentrations are higher at Tara than at any of these other potential sources,” Dr Santos said.
The federal government is currently reassessing its methodology for measuring greenhouse gas leakage from coal seam gas fields, and the researchers have sent a submission to the government asking it to take their work into account.
“These results provide strong evidence for significant, but still unquantified, greenhouse gas emissions in the Tara region,” the submission says. “Our results demonstrate the need for baseline studies before the development of gas fields. We suspect that depressurisation (fracking, groundwater pumping) of the coal seams during gas extraction changes the soil structure (i.e., cracks, fissures) that enhance the release of greenhouse gases such as methane and carbon dioxide.”
The findings were welcomed by opponents of large-scale coal seam gas drilling, including the Lock The Gate group which wants a moratorium on drilling until comprehensive tests are done.
“This study has massive implications for accounting for Australia’s greenhouse gas emissions since methane is a very potent greenhouse gas,” said the group’s president, Drew Hutton. “It also means the CSG industry would need to pay much higher carbon tax than is currently predicted.”
The Greens said a national, independent study was needed to accurately measure gas leaks.
“The gas industry has been hiding behind its claim to be better for the climate than coal for years, and the government has just accepted those claims despite the Greens, farmers and scientists providing evidence that they are deceptive,” said the Greens leader, Senator Christine Milne.
“It makes no sense to develop a new fossil fuel industry at the end of the fossil fuel age, particularly when it is compromising food growing land and contaminating aquifers.”
The Tara gas field operation is owned by BG Group, a British multinational gas and oil company. It directed questions to the industry body APPEA.
“Incomplete research from Southern Cross University academics this week lacks the basics of scientific rigour,” APPEA’s chief operating officer for the eastern region, Rck Wilkinson, said in a statement. “What is presented as research is in reality a funding submission.
“The claim that large-scale fugitive gas emissions are a result of coal seam gas production, before they even do their research, seems to indicate a bias against coal seam gas,” Mr Wilkinson said.
“This does them no credit and it diminishes the good work by many other scientists in an age where scientific endeavour has been wearied by community scepticism.”
The researchers have submitted two papers on their findings, which have been seen by Fairfax, and the papers are currently undergoing a peer-review process prior to publication.
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