Synthesized natural gas burns into flame in a coal chemical plant in Huaibei, Anhui Province, on September 26. Photo: IC

China's stepped-up efforts to combat air pollution might worsen water shortages in already deprived areas, scientists and environmental protection organizations have warned.

One of the key measures China announced to cut fossil fuel consumption is promoting other energy sources, including synthesized natural gas (SNG) from coal. But studies have found that the process of turning coal to natural gas requires a lot of water and most of the approved SNG stations are located in areas like the Xinjiang Uyghur and Inner Mongolia autonomous regions, where water shortages are already a headache.

Air pollution has frequently been in the headlines this year, due to increased levels of smog over many of China's major cities. The levels of airborne particulate matter of 2.5 microns or less (PM2.5), regarded as the most harmful to human health, reached dangerous levels in cities like Beijing. Last month, heavy smog hit Harbin in Northeast China, forcing highways, airports and schools to shut down.

On September 12, the central government issued an action plan for air pollution prevention and treatment, aiming to improve air quality within five years. A key measure is adjusting the types of energy used to reduce the consumption of fossil fuel, which is the main cause of  pollution in China. The plan aims to bring the consumption of coal down from 67 percent of total energy consumption recorded in 2012, to below 65 percent by 2017.

In an attempt to control air pollution, the Beijing municipal government, for example, has issued its own targets, which specifically aim to bring the density of PM2.5 down by 25 percent by 2015.

However, environmentalists point out that given the modest reduction targets, growth may outpace the cuts.

Water-hungry solution

To replace coal, the government plans to promote energy sources such as natural gas, SNG, hydropower, wind and nuclear power.

Soon after the plan was released, two research fellows at Duke University in the US cautioned against building large scale SNG plants in China in an article published on Nature Climate Change online.

It requires six to 12 liters of water to produce a cubic meter of SNG, 50 to 100 times more than it takes to produce per cubic meter of methane from shale gas, according to the paper, using data from research conducted both in China and abroad. The paper also says that the greenhouse gas emissions during the process of synthesizing natural gas from coal are seven times those of conventional natural gas.

On October 23, the World Resources Institute (WRI), a nonprofit global research organization, issued a similar warning regarding the growth of SNG projects as a means to reduce air pollution. The institute placed the locations of approved SNG plants on its Aqueduct Water Risk Atlas, which uses publicly available data about water volume, water quality and related information to assess the status of water resources in an area.

There is no official number revealing the exact number of SNG projects in China. The WRI paper uses 18 approved large-scale SNG plants with a total capacity of 75.1 billion cubic meters of natural gas per year.

"More than 76 percent of the proposed SNG capacity will face high or extremely high baseline water stress," the article reads, meaning they will have to compete with many other users for limited water supplies, or have very little water available at all.

According to the WRI, the five approved SNG plants in Ordos, Inner Mongolia, will need about 140 million cubic meters of freshwater a year, which represents about 10 percent of the city's water supply.

Shifting the problem

"If we look at the policies, the government is cautious about developing such projects in arid areas. Before this year, only four projects had been approved, and they were approved years ago," said Wen Hua, a researcher at the WRI.

Since 2010 the authorities have stopped approving new SNG plants. But pressure to reduce air pollution, the increasing demand for natural gas, and concerns about energy security as China imports more natural gas from foreign countries, have all contributed to rapid growth in SNG projects, said Ma Jun, director of the Institute of Public and Environmental Affairs.

All signs seem to indicate a bright future for the SNG industry, many consulting agencies and industry analysts suggest. In September, the National Development and Reform Commission approved a 180-billion-yuan ($29.5 billion) project in Xinjiang with an annual capacity of 30 billion cubic meters of SNG. An SNG plant in Inner Mongolia will also provide 4 billion cubic meters of natural gas annually to Beijing, starting this winter.

AsiaChem consulting, a coal chemical consultancy, estimates that there were close to 30 plants under construction or being planned in Xinjiang alone in 2012. The Southern Weekly estimates over 60 SNG plants are currently under construction, with a total annual capacity of 260 billion cubic meters, which will be more than enough to satisfy the levels of demand projected for 2015.

Most of the plants are located in Inner Mongolia and Xinjiang, which are rich in coal. Besides water shortages, such projects may also cause water pollution and damage the grassland, grass-roots environmental organizations have warned.

Beijingers might be able to benefit from cleaner natural gas, but the risk of water shortages and pollution is being shifted to areas where natural gas is produced, said Wen.

Dire warnings

The action plan to treat air pollution says that China should speed up industrialization and scale up SNG production, provided the projects meet strict environmental requirements and don't harm water resources.

Although well-intentioned, such statements are too vague to be enforced, said Wen. But he said there are many good measures in the action plan, such as tackling the problem at its source by reducing energy consumption, as well as adjusting the industrial structure of the country. "I think the government should at least look at different options and choose those that have smaller environmental impacts," Wen said, adding that different decision makers probably don't see the whole picture.

"When trying to reach the goals for air quality, we also have to consider goals in other areas such as water conservation and greenhouse gas emissions," said Ma. "If we don't take a long-term, comprehensive view, there will be ecological consequences but also impacts on the economy as the whole industry won't be sustainable."

Researchers at Duke University voiced much stronger warnings. "At a minimum, Chinese policymakers should delay implementing their SNG plan to avoid a potentially costly and environmentally damaging outcome. An even better decision would be to cancel the program entirely," said the article.