This "historic" drop would be equal to 300 Terawatt hours (TWh), or more than the combined coal-based electricity output of Germany, Spain and Britain last year, the UK-based Carbon Brief website said.

The turnaround is largely due to "record falls in developed countries, including Germany, the EU overall and South Korea, which are not being matched by increases elsewhere."

"The largest reduction is taking place in the US, as several large coal-fired power plants close," it added.

For 2017-2918, falls in the US and the European Union were "offset by increases elsewhere, particularly in China," Carbon Brief said.

"This year, however, the fall in developed economies is accelerating, while coal generation in India and China is slowing sharply, precipitating a global reduction."

In the past 35 years, there have been only two overall coal power declines -- 148 TWh in 2009 in the wake of the global financial crisis and 217 TWh in 2015 as China slowed.

- China still dominant -

In China, coal tends to fill the gap between clean energy growth and rising demand, Carbon Brief said.

"This means that when electricity demand is growing strongly, coal dependence comes to the fore."

The study noted that Chinese firms have continued to add new coal-fired power plants at a rate of one large facility every two weeks, even as average plant utilisation rates tumble to record lows below 50 percent.

The result is that China "still dominates the global picture" in coal-fired electricity generation which "peaked unexpectedly" in 2014 when the world's second largest economy began to cool off.

In the US, coal-fired power generation was down 13.9 percent through to August this year while in the first six months of 2019, European Union output tumbled 19 percent.

For the full year, the EU could drop as much as 23 percent, Carbon Brief said.

- Key climate change factor -

The future of coal-fired electricity "has significant implications for global efforts to tackle climate change," it noted.

Last year, a three percent increase in CO2 emissions from coal-fired power generation was responsible for half the global increase in emissions from fossil fuels.

For 2019, a three percent reduction could imply zero growth in global CO2 output, if emissions changes in other sectors mirror those during 2018.

These changes are significant but the study still noted that this year's projected 3.0 percent fall would be only half the 6.0 percent drop the International Energy Agency says is necessary each year to 2040 to bring about its "Sustainable Development Scenario" aimed at limiting global warming to below 2C.

The World Meterological Organization said Monday that greenhouse gas emissions hit a new all-time high in 2018.

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