China's recently announced effort to combat the smog blighting its eastern cities will exacerbate the water stress facing the country, a new report has warned.
The first day of winter heating saw the north-eastern city of Harbin, which has 11 million inhabitants, virtually shut down by a blanket of soot this week, illustrating the problems caused by China's addiction to burning coal.
The country last month launched its Air Pollution Control Action Plan in a bid to cut smog in the North China Plain by a quarter and reduce coal's share of the national energy mix to 65% by 2017, down from about 70% now.
But its strategy involves replacing coal-burning with cleaner natural gas, including using synthetic natural gas (SNG) converted from coal.
SNG plants require water for cooling, production, and to remove contaminants post-production, and the World Resources Institute (WRI) warns that while the technology will help reduce smog, it will also drive up water consumption, including in areas where the resource is already scarce.
"Converting coal to natural gas is an extremely water-intensive process," says the WRI in a blog. "One cubic metre of SNG requires 6 to 10 litres (1.6 to 2.6 gallons) of freshwater to produce. So, in an attempt to control urban air pollution in the east, China might jeopardise its water supplies elsewhere."
Research carried out by the WRI showed that many of the 18 approved large-scale SNG plants are located in water-stressed regions, mostly in arid and semi-arid regions in Xinjiang and Inner Mongolia.
It believes these plants will consume a total of 500 to 700 million cubic metres of freshwater to produce 75.1 billion cubic metres of natural gas a year. This accounts for almost a fifth of the regions' total industrial water use.
Beijing will become the first Chinese city powered by SNG, receiving at least 4 billion cubic metres of the fuel annually from Inner Mongolia. The blog argues that this production would consume more than 32 billion litres of freshwater a year – enough to meet one million Inner Mongolians' domestic needs.
Meanwhile, five SNG plants have been approved to supply the city of Ordos in the Mu Us Desert. The WRI found that the five plants will need approximately 140 million cubic metres of freshwater annually – about 10% of total water supply, or 40% of the region's industrial water use.
"Once these SNG plants are completed, they could further disrupt water supplies for farmers, herders, and other industries," the blog warns.
As well as the threats to the country's water supply, the WRI warns that using SNG may also be "a step backward for China's low-carbon energy strategy".
This is because, while SNG plants produce less soot than burning coal, it estimates that the lifecycle greenhouse gas emissions are 36%-108% higher.
"China's government will need to think carefully about whether SNG's air pollution benefits outweigh its water and climate change costs," the blog concludes. "To ensure a sustainable future, it's important for China to prioritise energy projects that face fewer environmental risks, especially from water and greenhouse gas emissions. Only then will China more successfully manage its conflict between economic growth and resource demands and find lasting energy security."
Peter Cripps
Channels:Policy