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Methane emissions from a large open-cast coal mine in Australia are three to eight times higher than reported. This has been revealed in a study based on aircraft-based measurements by the University of Bremen and Airborne Research Australia (ARA). It is the first time that precise data has been available.

Man-made methane emissions contribute significantly to global warming. Coal mining is responsible for about one-third of global methane emissions from fossil fuels. In the fall of 2023, researchers from the Institute of Environmental Â鶹ÒùÔºics at the University of Bremen and the non-profit research institute Airborne Research Australia (ARA) conducted airborne atmospheric measurements in the Bowen Basin in Queensland, Australia. These were carried out on behalf of the United Nations Environment Programme's (UNEP) International Methane Emissions Observatory (IMEO).

The aim was to gain a more comprehensive understanding of methane emissions from underground and surface coal mining. The German-Australian research team's of a large open-cast coal mine in the Bowen Basin, which is now available and published, documents that methane emissions are three to eight times higher than reported by the operator based on national emission factors.

Field Campaign with Research Flights in the Bowen Basin

In September/October 2023, the research team from the University of Bremen, together with researchers from the Airborne Research Australia (ARA) institute, carried out imaging measurements with the MAMAP2D-Light methane spectrometer. The University of Bremen's innovative remote-detection sensor was attached to the wing of an ARA research aircraft for the purpose. A second research aircraft was equipped with highly sensitive measuring devices from the Australian partners.

More than 40 research flights were conducted with both aircraft to detect and quantify methane emissions from various coal mines. The study, now available in the journal Environmental Science & Technology Letters, is based on the evaluation of the measurement data obtained in Australia in 2023.

"Establishing the link between atmospheric methane measurements and the emission factors of hard coal is one of the really important breakthroughs of this study," stated principal investigator Heinrich Bovensmann from the Institute of Environmental Â鶹ÒùÔºics at the University of Bremen.

Konstantin Gerilowski, who developed the MAMAP2D-Light remote sensing instrument at the University of Bremen, added, "It was amazing to see how the new generation of aircraft remote-detection sensors, with their specially optimized design for methane measurements, such as MAMAP2D-Light, developed their full potential for detecting methane emissions from open-cast coal mining and were even able to determine the origin of the emissions within the mine."

Stephen Harris, UNEP-IMEO scientist at the University of New South Wales in Sydney, Australia, also welcomes the study: "This study represents the first time we've verified an individual coal mine's methane emissions using aircraft-based measurements in Australia."

Manfredi Caltagirone, head of UNEP's International Methane Emissions Observatory, emphasizes, "The Bowen Basin is home to the majority of Australia's met coal used in steelmaking, and this work points to significant methane emissions in the sector that need to be abated.

"There is so much potential for the steel supply chain to step up, rein in its methane emissions, and have a real impact on climate in the coming years. We know methane from met coal production adds a quarter to steel's climate footprint, but we need better, verified data like those in this study to seize this mitigation opportunity."

New insights into quantifying methane emissions from steel production

The Bowen Basin is considered one of the largest coal mining areas in the world, with its coal being used primarily in steel production. In Germany, about half of the imported coal is used in steel production. In 2024, Australia was the largest exporter of coal to Germany.

The amount of hard coal imported from Australia doubled from around four million tons in 2020 to over eight million tons in 2024. This study highlights the significant potential for methane emissions reduction across the steel supply chain and the need for improved data to understand and reduce the sector's emissions.