The Department of Industry forecast shipments of thermal coal -- used in electricity production -- would be worth US$20 billion, down from US$43 billion this year.

The forecasts show a spectacular drop for a sector long championed by politicians and industry figures as a mainstay of the Australian economy.

Australia is currently the world's second-largest exporter of thermal coal, after Indonesia, and the largest exporter of metallurgical coal, which is used in steel making.

"Global supply and demand for thermal coal have peaked," the department said, forecasting price declines after spikes caused by the Covid-19 pandemic and Russia's invasion of Ukraine.

Demand from China -- the world's largest coal importer -- is expected to begin a "long-term decline" starting in 2024.

But the Australian forecast noted that the pace of the declines in the coal market "is likely to be uneven" and volatile.

"The gradual withdrawal from thermal coal usage is likely to affect lower grade and higher-polluting blends in the first instance." 

The Department of Industry report also predicted a continued boom for materials such as nickel, manganese, cobalt and lithium used in batteries.

Exports of those commodities are expected to pass US$27 billion per year, eclipsing the value of thermal coal exports, a sign of how new technologies and emission reduction targets are changing energy markets.