Heavy water use, threats of tainted groundwater, and artificial earthquakes are but a sampling of the environmental side effects that have tarnished North America's recent boom in natural gas production via hydraulic fracturing or fracking. No surprise then that in European countries such as the U.K. that are looking to frack for cheap domestic gas, the environmental protesters often arrive ahead of the drill rigs.
But countries seeking fresh gas supplies could do far worse than fracking. So say Duke University researchers who, in today's issue of the research journal Nature Climate Change, shine a jaundiced spotlight on China's plans to synthesize natural gas from coal. Nine synthetic gas plants recently approved by Beijing would increase the annual demand for water in the country's arid northern regions by over 180 million metric tons, the Duke team concluded, while emissions of carbon dioxide would entirely wipe out the climate-cooling impact of China's massive wind and solar power installations.
"At a minimum, Chinese policymakers should delay implementing their synthetic natural gas plan to avoid a potentially costly and environmentally damaging outcome," says Chi-Jen Yang, a research scientist at Duke's Center on Global Change and the study's lead author, in a statement issued yesterday.
Synthetic gas plants use extreme heat and pressure to gasify coal, producing a combination of carbon monoxide and hydrogen. Steam and catalysts are then added to convert those gases to methane to produce a pipeline-ready substitute for natural gas.
It takes a whole lot of steam: According to Duke's estimates, China's synthetic gas plants will consume up to 100 times as much water (per cubic meter of gas) as shale gas production through fracking.
Relative greenhouse impact is harder to pinpoint because fracking's climate footprint remains controversial. Recent U.S. Environmental Protection Agency and industry studies dispute earlier results suggesting that fracked wells leak more methane—a potent greenhouse gas—than conventional wells.
What is certain, say Yang and his colleagues, is that synthetic gas production will be carbon intensive relative to conventional gas. Burning conventional natural gas to produce power releases two to three times less carbon into the atmosphere than when burning coal, but burning synthetic gas will be 36 to 82 percent dirtier than coal-fired plants.
Capturing and storing CO2 emissions could slash the climate costs, and China may have the technology to do it. Last year, Chinese power firm Huaneng started up the world's most advanced coal gasification power plant, which sports equipment to efficiently extract carbon waste from gasified coal. Similar technology could potentially enable China's synthetic gas plants to capture and sequester their CO2 instead of sending it up the stack.
Of course adding such equipment adds to construction and operating costs. Duke's team clearly doubts that Beijing will make synthetic gas producers go there.
Photo: David Gray / Reuters
Peter Fairley has been tracking energy technologies and their environmental implications globally for over two decades, charting engineering and policy innovations that could slash dependence on fossil fuels and the political forces fighting them. He has been a Contributing Editor with IEEE Spectrum since 2003.