On Friday, the stock-exchange listed Yancoal announced it would repay $1 billion in debt this week ahead of schedule, thanks to what chief executive David Moult called "substantial cash inflows during periods of elevated coal prices".

Yancoal recently published its interim annual results for the year ended June 30, showing the sheer scale of the rebound in prices across the past two years, with a before tax profit of $2.45 billion and an after-tax result of $1.74 billion - up from the previous year's losses of $177 million before tax and $129 million after tax.

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Its Moolarben (formerly Anvil Hill) mine returned an after-tax profit of $1.01 billion, up from $45 million in the 2021 financial year.

Warkworth made $285 million ($27 million previously), Mount Thorley $93 million (a $6 million loss previously) and Yancoal's 51 per cent share in Hunter Valley Operations returned $487 million, up from $14 million.

Coal prices - and Yancoal's share price - are so high that its Chinese government backed parent company last month abandoned its bid to buy the remaining third of the company it did not own, citing "market conditions" as the reason it was "terminating the potential transactions".

Industry-wide, the Office of the Chief Economist in Canberra predicts earnings of $60 billion this financial year from coking coal - mainly from Queensland - and $44 billion from thermal coal, much of it shipped through Newcastle.

It predicts a one-third drop in earnings in 2023-24 to $41 billion in coking coal and $31 billion in thermal coal, but even these figures would be higher than anything earned during previous booms.

Although the market shortages caused by sanctions on Russian coal and gas are blamed by some commentators, records show prices were rising steeply well before the Russian invasion of Ukraine, arguably because renewable hype was running ahead of the ability of wind, solar and hydro to provide sufficient power to meet existing needs.

The International Energy Agency recently reported that subsidies (including power price relief) to fossil fuels had doubled in 2021, and described them as "a roadblock" to the installation of renewables.

It also predicts global coal consumption to equal the record set in 2013 and beat it next year, "contributing significantly to the largest ever increase in global energy-related CO2 emissions" to their "highest level in history".

Late last year the agency predicted three years of record output.

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