Australia's methane emissions from coal mines are twice as high as national estimates, with some mines leaking up to 10 times more methane than officially reported, research by an international climate think tank has found.
European-based researcher Ember was commissioned by the environmental group, Lock the Gate Alliance, to analyse available data on methane emissions from the Australian Greenhouse Emissions Information System (AGEIS), the Clean Energy Regulator (CER), the Australian Chief Economist, Department of Natural Resources and Mines, the International Energy Agency (IEA) and the Global Energy Monitor.
Methane is a powerful greenhouse gas and its global warming potential is more than 25 times that of carbon dioxide.
The report found that in 2019, Australian coal mine methane emissions made up 68 per cent of overall energy industry emissions, making it a bigger contributor than oil and gas.
"That's a really massive climate impact before we even start to think about the carbon dioxide emissions released from burning coal."
The Queensland coordinator for Lock the Gate, Ellie Smith, said the report had found that "there is massive under-reporting of methane emissions in Australia".
"So we're not taking into account all of these emissions in our national accounting framework," she said.
The report also revealed new data from the IEA, which estimated that Australian coal mines emitted 1.8 million tonnes of methane in 2021 — double what had been officially reported.
Hail Creek coal mine is owned by Australia's largest coal producer, Glencore, and the company has previously told the ABC "it's not credible" that a single mine could be responsible for such a large amount of methane emissions.
"Glencore has an established track record of emission reduction," a Glencore spokesperson said.
Glencore said emissions from all of its operations were accounted for in its "robust" climate targets.
"These targets include a 15 per cent reduction in total (including Scope 3) emissions by 2026 – a 50 per cent reduction in total emissions by 2035 and an ambition to be a net-zero total emissions company by 2050," a spokesperson said.
The Ember report also mentions Anglo American as another major coal miner operating some of Australia's "gassiest" mines.
"We are actively working on technology solutions to further reduce methane emissions in our underground metallurgical coal mines, as part of our commitment to operate carbon neutral mines by 2040," an Anglo American spokesperson said.
What is coal methane?
After carbon dioxide, methane is the second biggest contributor to global warming.
Coal seams and methane gas are produced during the process of geological decomposition and compression of organic material deep underground, usually over tens of millions of years.
Methane gas is the same as the 'natural gas' targeted by gas companies and is released during the mining of coal.
In open-pit coal mining, methane is released when the coal seams are broken up, and in underground coal mining, methane has to be 'vented' because at high concentrations it is an explosive risk.
Methane can continue to penetrate underground formations and escape for decades after coal mining ends.
Why the discrepancy?
As mentioned, underground coal mines have to monitor methane because it is an explosive risk, but measuring methane over vast open-pit coal mines is more difficult, so it has to be estimated using an emissions factor.
The other reason why the IEA data and Australian regulator coal methane records are so different is that it references new satellite information.
"I think the solution really is to combine satellite measurements with actual direct measurements on the ground, that's the only way we can really get a good picture of what's going on," Dr Assan said.
Professor Peter Rayner, an atmospheric scientist from the University of Melbourne, said the discrepancy in methane reporting was not necessarily deliberate.
"I think all the operators, and probably the government, are getting away with doing things more simply than they can," Professor Rayner said.
Methane's big 'short-term impact'
Australia currently measures the global warming potential of methane over 100 years, but Ember researchers said that did not accurately measure its impact.
"The difference between methane and carbon dioxide is that methane has a much stronger heating effect in the short term compared to carbon dioxide, so around 82 times that of CO2 over 20 years," Dr Asssan said.
At the Glasgow climate summit last year, Australia failed to join the US, EU, and more than 100 other countries in signing the Global Methane Pledge to "reduce global methane emissions by at least 30 per cent from 2020 levels by 2030".
The ABC has contacted the Minister for Climate Change and Energy, Chris Bowen, but has not received a response.
In addition to the International Energy Agency finding that no new coal mines can be developed if the world is to reach net-zero by 2050 , a recent UN report found that coal output needed to be reduced by 11 per cent each year to 2030 to limit global warming to 1.5 degrees.
There are 68 proposed coal projects across New South Wales and Queensland.
The Ember report found that if those projects were to be developed, Australia would become "the third-highest potential emitter of new CMM [coal mine methane] emissions after China and Russia".
Minerals Council of Australia CEO Tania Constable said the mining industry was taking action on climate change and was committed to net zero emissions by 2050.
"The Australian coal industry has invested over $30 million to develop guidelines to assist the industry in meeting these requirements for both underground and surface mines," she said.
Adopting new technology
Ember researchers said Australia's coal industry needed a more robust methane emissions monitoring and reporting system, which incorporated new satellite monitoring technology.
"New satellites such as EnMAP, Carbon Mapper, CHIME, EMIT and MethaneSat will provide a more thorough picture of Australia's CMM emissions and force improved transparency and methodology," the report said.
According to the report, abatement measures for coal mine methane are available.
It argues that vented air methane (VAM), which makes up most of the emissions, should be banned.
"The dominant means of reducing the climate impact of VAM is capturing the gas and either extracting or destroying the methane," the report said.
The method still produces CO2, but not the more potent methane.
The CSIRO has also developed technologies to capture or limit methane emissions, including a machine that "uses a catalytic combustion gas turbine to create electricity from captured methane".
"If applied to all underground mines, this technology has the potential to reduce Australia’s methane emissions by approximately 45 per cent," the report said.
