Clean coal is, once again, having a bit of a moment. The suite of technologies that the industry hopes could one day remove carbon dioxide from exhaust at coal-fired power plants around the world is featured in this month's issue of National Geographic. It's on the cover of Wired, too.

It's true that clean coal could become a very valuable technology. Coal is ordinarily a very dirty fossil fuel, which produces particulate pollution and other toxins in addition to large amounts of carbon dioxide when it is burned. Yet it would be impossible to get rid of coal entirely. It is the source of about 40 percent of the world's electricity, and it is also indispensable in industries such as cement and steel. Coal is also a reliable source of power, unlike the wind and the sun. Engineers can depend on coal to burn steadily, no matter the weather. A grid built largely around wind turbines and solar panels would be impossible to operate given current technology.

Yet the recurring buzz around clean coal isn't much more justified this time around than it has been previously. Perhaps even more than other new energy technologies, clean coal is still mostly experimental, and it remains exorbitantly expensive. China has invested heavily in the technology, and if the research goes well, clean coal might prove enormously beneficial there -- but perhaps less so in other countries, and the United States might not ever have much use for it.

Clean coal is important to Chinese leaders partly because of the country's large coal reserves. "They have so much coal, and their whole infrastructure is geared around coal," said Kelly Sims Gallagher of Tufts University. The country has built many new coal plants in the last decade, and these plants could theoretically be retrofitted with new equipment to capture carbon dioxide. Also, the Chinese government has also built several plants that vaporize coal before it is burned. The process clears up soot and smog in urban areas, but produces even more carbon dioxide. There would be no shortage of opportunities for Chinese engineers to use clean coal technology if it were available.

Other sources of energy, like renewable and nuclear power and natural gas, will be necessary for China all the same if the country hopes to control its carbon dioxide emissions. Clean coal "needs inevitably to be part of the solution in China, but it’s not the only solution. Far from it." said Gallagher, who just published a book on energy technology in China. Different kinds of power can serve different purposes, and it's impossible to predict which technologies will develop most successfully.

The article in Wired by Charles Mann is thoroughly reported and makes for a fascinating read, but nothing in it supports the magazine's thesis about clean coal: "Because it could allow the globe to keep burning its most abundant fuel source while drastically reducing carbon dioxide and soot, it may be more important -- though much less publicized -- than any renewable-energy technology for decades to come." For one thing, clean coal is not obviously less publicized than renewable energy technologies. The coal industry has spent massively on advertising for it, and clean coal graced the cover of The Atlantic way back in 2010.

More to the point, while clean coal might be more important than other clean sources of energy in China, other countries do not depend on coal in the same way that China does. In about ten years or so, India, not China, will be the largest source of new demand for energy, according to the International Energy Agency. While both countries have been building a fleet of colossal new coal-fired power plants, India does not have its own reserves of coal and has to rely on imports from places like Indonesia. Given the cost of shipping and (less so) the apparent tendency of Indonesian coal to burst into flames without warning, Indian officials might prefer to rely on solar power rather than clean coal if compelled to reduce their carbon dioxide emissions. On the other hand, there is the question of how much more variability the country's overtaxed power grid can handle.

In the United States, the case for clean coal is even weaker. According to a recent estimate from the U.S. Energy Information Administration, a new clean-coal plant built now costs about as much as a new solar plant per unit of electrical generation -- and that estimate looks optimistic next to the even higher costs Mann reports in Wired. U.S. coal power plants are much older than the new Chinese fleet, and it wouldn't make sense install fancy new cleaning equipment at facilities that will need to be decommissioned soon anyway. Perhaps scientific progress or shifting geopolitical constraints will make coal relatively cheap again in the United States. "I wouldn't put it past the market to revert to coal," Gallagher said. For now, though, wind and natural gas are much less expensive sources of electricity. Meanwhile, the cost of solar panels is falling steadily and predictably, and solar energy is no more expensive than the market price for electricity in parts of Europe.

Clean coal is important, to be sure, but it's hardly news. National Geographic's editors handled the story well, being careful not to overstate their conclusions. It would have been great to read a piece in Wired about any of the various fascinating new energy projects that truly aren't well publicized: supercapacitors, fusion reactors, batteries made out of air. These technologies might not be as far along in their development as clean coal, but their implications are arguably just as broad. Then again, stories that are uncomfortable for the environmental movement have always been popular with editors and their audiences, probably because they give a publication an aura of iconoclastic thinking, however undeserved it may be.