The coal-powered synthetic natural gas plants that are being planned in China would produce seven times more greenhouse gas emissions than conventional natural gas plants, and use up to 100 times the water as shale gas production, according to a new study by Duke University researchers.

These environmental costs have been largely neglected in the drive to meet the nation’s growing energy needs, the researchers say, and might lock China on an irreversible and unsustainable path for decades to come.

“Using coal to make natural gas may be good for China’s energy security, but it’s an environmental disaster in the making,” said Robert B. Jackson, professor and director of the Duke Center on Global Change.

As part of the largest investment in coal-fuelled synthetic natural gas plants in history, the central Chinese government recently has approved construction of nine large-scale plants capable of producing more than 37 billion cubic meters of synthetic natural gas annually. Private companies are planning to build more than 30 other plants, capable of producing as much as 200 million cubic meters of natural gas each year — far exceeding China’s current natural gas demand.

“These plants are coming online at a rapid pace. If all nine plants planned by the Chinese government were built, they would emit 21 billion tons of carbon dioxide over a typical 40-year lifetime, seven times the greenhouse gas that would be emitted by traditional natural gas plants,” Jackson said. “If all 40 of the facilities are built, their carbon dioxide emissions would be an astonishing 110 billion tons.”

The analysis by Jackson and research scientist Chi-Jen Yang finds that if the gas produced by the new plants is used to generate electricity, the total lifecycle greenhouse gas emissions would be 36 per cent to 82 per cent 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-fuelled vehicles.

Excessive water consumption by the plants is also a concern because producing synthetic natural gas requires 50 to 100 times the amount of water needed to produce shale gas, explains Yang. As most of the plants are located in desert or semi-desert regions, this could worsen water shortages in areas that are already under significant water stress.

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