“I suspect we will have severe incidents of air pollution in Beijing again this winter,” said Alvin Lin, China Climate and Energy Policy Director for the US-based Natural Resources Defence Council.

The government sees natural gas as the way to cleaner air. Authorities have said Beijing’s urban core should use only gas for heating. But domestic output cannot keep up with demand.

“With the current natural gas situation, maybe you can guarantee [supply to] big cities like Beijing, but if you want to expand to the cities of northern China that need it ... I think that’s still quite difficult,” said Tao Guangyuan, a renewable energy expert and columnist based in Beijing.

The shortage has forced the government to ration gas supplies, even banning construction of new natural gas-fired power stations. It also said last week it would control the increase in new gas users, prioritising supplies to residential consumers and public transport during the winter.

Nevertheless, the gas shortage may still be 10 per cent higher this winter than last year because more users have switched over, official media said last week, citing an unidentified executive from PetroChina, the largest gas producer and importer in the mainland.

The government has said it would raise natural gas use to 230 billion cubic metres by 2015, more than double the 2010 rate, but disappointing domestic production growth coupled with insufficient pipeline and storage capacity has left it increasingly reliant on imports and prone to shortages.

Importers also risk losses because the government keeps the price of gas low to curb inflation and ease the impact on consumers, although recent incremental price hikes have helped.

“If there’s not enough gas, many people will just go back to burning coal, secretly,” said Ming Sung, East Asia chief representative of the Clean Air Task Force, a US-based environmental advocacy group.

The authorities want to tackle air pollution to stem potential unrest as its increasingly affluent urban populace turns against a growth-at-all-costs economic model that has spoiled much of the country’s air, water and soil.

China’s cities are among the world’s most polluted. Air pollution in Beijing – derided as “Greyjing” or “Beige-jing” by English-speaking residents – exceeded national standards 62 per cent of the time during the third quarter, the Ministry of Environmental Protection said.

Beijing authorities have unveiled a new smog alert system that will impose curbs on driving and halt manufacturing and construction if three consecutive days of hazardous pollution are forecast.

“I think there’s now more attention being paid to what are the immediate, short-term things that could be done when the air pollution gets that bad,” said Lin.

Images of the acrid smog over Harbin on October 21 were beamed around the world after authorities literally turned on the heat by switching on a network of mostly coal-fired heating plants that warm large swaths of the city. Officials blamed thick fog on the same day for contributing to the pollution.

The same sort of plants are used across northern China, providing so-called ‘centralised heating’. Some also supply electricity while others burn coal just to generate steam which is piped into city grids for heat.

Centralised heating dates back to the 1950s in Beijing. It had spread across the north by the mid-1980s. China was impoverished at the time, which meant the government could only afford to give its colder north centralised heating. Residents in cities south of the Yangtze River such as Shanghai tend to rely on electric space heaters.

Most of the north’s heating plants are turned on around mid-November. Many institutions and residential complexes have private heating, but also use coal-fired boilers.

The coal-fired heating plants use coal-scrubbing filters which reduce soot emissions, said Tao, the renewable energy expert. The real pollution culprits are small coal boilers, as well as traditional ‘kang’ – stove-heated beds that people sleep on – and other forms of ‘rustic heating’ residents depend on to survive cold winters. Such stoves produce tar and hazardous smoke, experts point out.

Air pollution in Harbin, which gets 65 per cent of its warmth from public and private centralised heating, was within WHO recommended levels on Tuesday after being 7.5 times acceptable levels on Monday.

Despite China’s rush to gas, coal still supplies the bulk of the country’s total electricity needs.

Under a new plan announced last month to tackle air pollution, China would cut consumption of the fossil fuel to below 65 per cent of primary energy use by 2017, down from 66.8 per cent last year.

The plan also aims to raise the share of non-fossil fuel energy to 13 per cent by 2017, up from 11.4 per cent last year.

PetroChina Chairman Zhou Jiping said earlier this year it would take at least four to five years to build-up new natural gas supply capacity, which would still not be enough to meet demand.

“For the whole country to move to natural gas in the way that you kind of see in the US ... it’s going to be a few decades,” said Lin of the NRDC.

Natural gas demand rose 13.5 per cent in the first nine months of this year for example, 4.3 percentage points faster than production, the government said last week.

With demand set to jump further, the government has put Beijing at the top of the list for supplies.

Beijing, Shanghai and Guangzhou in southern China are also expected to increasingly get energy from neighbouring regions under last month’s anti-pollution plan.

The capital, for example, is supposed to get 70 per cent of its power by 2017 from neighbouring regions, such as Shanxi and Inner Mongolia, where coal is still in widespread use.

“You can think of it as a redistribution of pollution,” Lin quipped.