Conservationists have called for an audit of potentially thousands of methane-leaking coal boreholes in Queensland, as one expert says New South Wales also has an unknown number of potentially leaking holes.
Research revealed last week that two abandoned exploratory coal boreholeswere leaking methane at a rate comparable to 10,000 vehicles.
The federal government has previously published estimates that there are about 130,000 abandoned coal exploration bores in Queensland’s Surat and Bowen coal basins where the quality of decommissioning to seal the holes is unknown.
The Queensland Conservation Council said the University of Queensland research had revealed “the tip of the methane iceberg”.
Charlie Cox, a coal and gas campaigner at the council, said the Queensland government should establish a statewide audit of boreholes.
“This is a perfect example of what coal royalties should be used for,” she said.
“And in cases like this where there is no apparent coal corporation still in operation to clean up the mess, the unmet costs of remediating these holes should be met by a levy on all current coalminers.”
She said if 5% of the estimated 130,000 legacy coal boreholes were emitting at similar rates to those found by UQ, “that’s the equivalent of 65m cars”.
Over a 20-year period methane warms the planet at a rate about 80 times greater than carbon dioxide.
Cox said “tackling methane is one of the fastest, most effective opportunities the Crisafulli government has to fight climate change”.
“We also ask the question, why would you add more methane to the problem with new coal and gas projects, when you don’t yet even have an accurate measure or handle on the burden left behind by coal boreholes like this one?”
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Dr Stephen Harris, an expert on greenhouse gas releases from the fossil fuel sector, said the research had highlighted “a potentially unaccounted for source of methane emissions not only across Queensland, but also other areas of Australia which have a long history of fossil fuel exploration”.
He said NSW government data showed there were more than 9,000 known coal exploration boreholes in the state.
“To this day, the number of abandoned boreholes remains unknown,” he said.
“In NSW, only a small number of coal exploration and water boreholes have been checked for methane, and those were found to be emitting very little. But it’s not clear if that’s the case everywhere, and this research shows there could be more out there that we just haven’t come across yet.”
Harris said the special cameras used by UQ had uncovered emissions from a borehole “that might have been missed or brushed off as too small to matter”.
He said measuring emissions from boreholes, and then properly sealing leaks, “can demonstrate clear reductions in methane released to the atmosphere, delivering a measurable benefit for the climate”.
The Queensland government did not respond questions on a potential audit of boreholes, and what mechanisms it had to recoup costs of sealing them.
