Underestimation of coal mine emissions

Australia’s open mines are reporting fugitive emission intensities only about one-tenth of those reported by underground mines. This appears to be due to prescribed methane estimation methods based on research 30 years old, rather than deliberate under-reporting.

Assuming that open cut coal mines have the same fugitive emission intensities as underground mines suggests that fugitive emissions from open cut mines were under-estimated by about 84 Mtonnes of CO2 equivalent in 21-22.

We conclude that

• Emission estimates for underground coal mines may be about right

• Methane emissions from open cut mines appear to be strongly underestimated

• Current emission estimation methods for open cut mines should be abandoned

• Open cut coal mines should be required to measure their emissions directly

• Regulatory authorities should use satellite observations as broad checks

• Retrospective changes to Australia’s emission reports may be needed

• The Climate Change Authority needs reliable data to meet its responsibilities.