The heavy environmental toll of China's solution to coal

Synthetic natural gas plants could actually increase greenhouse gas emissions, water shortages, and harmful pollutants, a new study shows.

Last month, China and the U.S. -- the two biggest carbon emitters -- announced large cuts in coal consumption and proposed a 40 percent reduction in emissions from coal-fired power plants, respectively.

That heavy haze above Northern China’s shortens the life spans of northern city-dwellers by as much as five years. The new environmental target is to trim coal’s contribution to overall energy output from 67 percent in 2012 to 65 percent in 2017.

Unfortunately, one scheme to limit coal burning by converting China’s plentiful coal supplies into synthetic natural gas (SNG) presents a host of other ecological worries, Businessweek reports.

To date, China’s government has approved construction of nine large SNG plants in northern and western China, which are projected to generate 37 billion cubic meters of gas each year when completed; at least 30 more are awaiting approval. None are located near large cities, so the emissions generated in producing the gas won’t hang directly over population centers.

But that doesn’t mean the coal-to-gas conversion process is clean. According to a new Duke University study published in Nature Climate Change:

If the gas produced by the new plants is used to generate electricity, the total lifecycle greenhouse gas emissions would be 36 percent to 82 percent higher than pulverized coal-fired power.

If the synthetic natural gas made by the plants were used to fuel vehicles, the lifecycle greenhouse gas emissions would be twice as large as from gasoline-fueled vehicles.

Additionally, converting coal to gas is a water-intensive process -- requiring up to 100 times as much as shale gas productions -- worsening water shortages in areas already under significant water stress (such as the semi-desert regions where SNG plants will be). Also, the plants would emit hydrogen sulfide and mercury, which, if not properly scrubbed and treated, are potentially harmful to human health.

Basically, the overall environmental impacts will be severe. “It will lock in high greenhouse gas emissions, water use and mercury pollution for decades,” said study coauthor Robert Jackson of Duke.

Although, as SmartPlanet’s Mark Halper reported , China is considering cleaning up the process by using the heat from small nuclear reactors (such as molten salt reactors) to power the conversion.

[Duke news via Businessweek]

Image: Marko Kudjerski via Flickr

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