Revision comes as a result of several challenges during commissioning the mine's first Autonomous Haulage System fleet.

Alcoa will cut its direct and some indirect emissions -- known as Scope 1 and Scope 2 -- from aluminum smelting and alumina refining operations.

The miner is in early discussions with billionaire Robert Friedland’s Ivanhoe Mines to buy into the Western Foreland project.

"Green hydrogen is the solution we need to get to absolute zero,", said Andrew Forrest.

The federal government-controlled miner has already announced plans to invest in solar wafer manufacturing and power generation.

BHP's Escondida, the world's largest copper mine, saw production drop 14% year-on-year.

The impact of the measure on production is still under evaluation.