The Clean Energy Regulator has given the Grosvenor mine the ability to emit 3.3 million tonnes of CO2 equivalent before Anglo has to buy carbon credits.

The approval was granted in March under the Morrison Government.

According to the Australian Conservation Foundation, the level of emissions was equal to the emissions of 400,000 cars.

ACF climate change campaigner Suzanne Harter said the approval highlighted how the Coalition Government’s safeguard mechanism “was absolutely useless as a tool to cut climate pollution”.

The ACF and the Australian National University had previously found that a third of fossil fuel projects emitted more pollution than has been estimated in the approval process.

“Some of the worst offenders emitted 20 times more than estimated,” Harter said.

Anglo said Grosvenor’s safeguard mechanism baseline increase reflected the specific geological conditions in areas where mining was to occur.

It said it had also invested significantly in methane capture infrastructure. About 65 per cent of the methane was captured and used for onsite power generation which went into the grid and was equivalent to the electricity demand for 90,000 Queensland homes a year. It also reduced its emissions by about 5 million tonnes of CO2 equivalent a year.

“We expect some normal fluctuations based on geological and production factors, up until we can safely deploy new technology and infrastructure to capture the additional methane that we cannot capture today,” an Anglo spokesperson said.

“There are currently technical challenges to capturing methane in underground coal mines, where it has been mixed with oxygen to make it safe to mine. As part of our commitment to operate carbon neutral mines by 2040, we are actively working on technology solutions to further reduce methane emissions.”

ACF said there was an expectation that the new Albanese Government would crack down on polluters as one way to reach its emission reduction target of 43 per cent by 2030.

The revelation came as the Queensland Resources Council called on the Government to declare the New Acland coal mine expansion a prescribed project, which would mean the Co-ordinator General could ease the path of its approvals.

The project has been in waiting for approval for more than a decade and has been to the High Court and back. It was recently granted environmental approval but was still waiting for a mining lease and water licence from the State Government.

The State Government said the remaining approvals for the expansion would be considered by the Minister for Resources once he had received it from the department. The associated water licence would come the Department of Regional Development, Manufacturing and Water.