While use of coal for generating electricity has started to decline in the U.S., China continues to build coal power plants.

With public anger at filthy air bubbling below the surface, and the costs of associated health effects more apparent, the country's government is well aware of the long-term costs. And that's even before factoring in climate change.

Two years ago, the Chinese government announced a plan to cap coal consumption through 2015--both to address air pollution and limit its imports of the commodity from Australia and elsewhere.

Street-level smog in Beijing

Street-level smog in Beijing

China also raised its target for new solar installations this year to 14 gigawatts--higher than last year's 12 GW, and more than any nation has ever added in a year.

While 40 GW of new coal generating capacity was added last year, China has also shut down more than 80 GW of the oldest, dirtiest coal generation over the last decade.

Now, energy analysts are beginning to fear that investment in coal powerplants in China bears the hallmarks of a speculative boom that some call "the carbon bubble."

The country's economy, huge as it is, will not necessarily absorb all of the new electricity produced, inevitably leading to bankruptcies--as China is now experiencing in its overinflated solar-power sector.

To varying degrees, the governments of the world have committed to reducing global temperature increase to 2 degrees C--which will require carbon emissions 60 to 80 percent lower than today's levels--over the next few decades.

Yet investments by large funds in coal mining and exporting companies aren't taking those goals into account. In essence, they're betting that nothing much will be done to cut carbon emissions.

The U.S. has already seen carbon fall as a proportion of its electric generation mix, and that decline is expected to continue, using increasingly cheap hydrofractured natural gas and growing amounts of renewable energy.

Will we see a view emerge that coal resources are become a stranded asset, overvalued on the world's books as an asset that will never actually be extracted and used?

The chance of that scenario--unthinkable just 10 years ago--may be increasing with each passing year.

As USA Today notes, "when China makes a decision, it almost always follows through."


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