Together the Australian coal mines account for 7% of the national coal production, but turn out to emit around 55% of what Australia reports for their total coal mining methane emissions. All findings were published today in the scientific journal Environmental Science & Technology. Earth scientists Sander Houweling and Ilse Aben of VU Amsterdam are involved in the research.
Australia is in the top-5 coal producing countries in the world. It reports coal mining methane emissions of a million tons per year. ‘It is hard to believe that 7% of coal production is responsible for 55% of coal mining methane emissions,’ says Aben, leading the team of researchers. ‘So in reality, Australia’s coal mining methane emissions are likely much higher than reported. More importantly, knowing which mines have such large emissions is critical in focusing efforts for mitigation.’ Aben is endowed professor at the Earth Sciences department of VU Amsterdam and also senior scientist at the Netherlands Institute for Space Research (SRON).
High emissions surface mine
The research team observed five underground mines and one surface mine. Especially the emissions from the surface mine, called Hail Creek, stand out. It is one of 73 surface mines in Australia, but accounts for 88% of Australia’s total reported surface coal mine emissions. First author Pankaj Sadavarte (connected to SRON and TNO): ‘The most remarkable finding is that the emissions from the surface mine are so much higher than expected, and by far the largest we see in the TROPOMI data over the coal mine area in Queensland: on its own it accounts for 40% of emissions for all six observed mines. Common understanding is that surface mines emit much less methane than underground mines. And to be quite honest, we still don’t understand why this mine is emitting so much methane.’
‘Hail Creek once again demonstrates the value of measuring greenhouse gases from space and shows the rapid development of this technique,' says Houweling, professor of atmosphere and greenhouse gases at VU Amsterdam. ‘The detection of methane leaks is still limited to very large sources, but the detection limit can be lowered considerably. This can be expected to lead to a sharp increase in the number of measurable sources, which will bring large-scale monitoring of greenhouse gas emissions within reach.’
Global impact of methane
Methane has been recognized as crucial to mitigate climate change on the short term. Earlier this month, over a hundred countries signed the global methane pledge initiative from the US and the EU at the COP26 in Glasgow to reduce methane emissions with 30% -relative to 2020- by 2030. A few major methane emitting countries, including Australia, have not signed the pledge.
The TROPOspheric Monitoring Instrument (TROPOMI) is a space instrument on board the European Copernicus Sentinel-5 Precursor satellite. Worldwide, TROPOMI measures the composition of our atmosphere, which is relevant for research on climate and air quality.
Image caption: TROPOMI methane observations on two different days showing large signals from three coal mine locations. The most Northern location is the surface mine, while the other locations are underground mines. Northern: Hail Creek. Middle: Broadmeadow, Moranbah North, Grosvenor. Southern: Grasstree, Oaky North.