SYDNEY, Sept. 3 (Xinhua) -- Researchers have discovered that a single abandoned coal borehole in Australia is releasing methane equivalent to the annual greenhouse gas emissions of 10,000 cars.

With an estimated 130,000 similar boreholes across the Australian state of Queensland, sealing high-emitting sites could offer a cost-effective way to reduce emissions, according to a statement released Wednesday by Australia's University of Queensland (UQ).

Researchers used advanced gas detection technology to determine that 235 tons of methane were released per year from the single abandoned coal borehole in rural Queensland, revealing a potentially underreported source of methane in the atmosphere, it said.

"In terms of climate impact, that's on par with emissions from 10,000 new cars driving 12,000 kilometers each, every year," said Associate Professor Phil Hayes from UQ's Gas & Energy Transition Research Center, co-author of the study published in the Netherlands-based journal Science of the Total Environment.

Researchers took emission readings over a week at a farm in the Surat Basin in central southern Queensland, using a portable Quantum Gas LiDAR system, which more accurately captures emissions that vary over time than the current common measurement methods, such as handheld sensors.

Co-author Sebastian Hoerning from UQ said that there were thousands of abandoned coal holes and it was not known how well they are sealed -- if at all -- or how much methane they may be emitting.

"Sealing the worst offending boreholes represents a straightforward and cost-effective way to quickly reduce greenhouse gas emissions," Hayes said.

The researchers plan to expand their study to include more coal boreholes and explore other potential emission sources like water bores. ■