A satellite photo of Beijing taken by United States space agency NASA earlier this month showed the capital and the area to its south covered in thick, grey sludge.
On that day - November 4 - the air pollution index recorded its worst reading in six months, mainland media reported. Suspended particulate levels reached a dangerous 300 micrograms per cubic meter.
"The effects of heavy pollution on health are big," the Beijing Environmental Protection Bureau said in a health warning at the time. The sky was covered in an oppressive blanket of pollution that obscured the outlines of buildings just 20 meters away. People complained of headaches and sore eyes, and were warned to stay indoors and avoid strenuous activity.
That high level of pollution is an increasingly common occurrence and just another sign of the dire state of the air in China.
"It can be safely assumed," the United Nations Development Program's China Human Development Report concluded in 2002, "that Chinese citizens are exposed to many of the worst air-pollution levels."
Suspended particulates in mainland cities are, on average, three times worse than the levels in London and Tokyo.
The government's environmental protection agency concludes that more than 400,000 people die from pollution- related illnesses in China every year. Much of that comes from coal-fired power stations.
There are other major sources of pollution, too, as the events that unfolded in Harbin this week have demonstrated. A blast at a petrochemical factory in Jilin, 370km away, poured 100 tonnes of toxic sludge into the Songhua River that runs between the two cities. As the pollutants moved towards Harbin, the city authorities responded by shutting down water supplies for the three million inhabitants.
Beijing is making major commitments to improving the environment, including a push for renewable energy, says Yu Jie, climate and energy campaigner for Greenpeace Beijing.
"There is domestic pressure on the government [to turn to renewables] as pollution increases - seven of the world's 10 most polluted cities are in China," Yu points out.
In February this year, the National People's Congress released a landmark renewable energy law, which will require grid operators to buy electricity from non-fossil fuel sources and will offer financial incentives to projects developing renewable energy.
The government boosted its target to renewable energy contributing 15 percent of energy produced by 2020, although it admits coal will remain its main source of power for years to come.
The target includes large hydropower - an energy source often not considered renewable because of the environmental damage it can inflict through dams.
Today, just seven percent of China's energy comes from renewables, including large hydropower. Excluding large hydropower, renewables make up about 3.5 percent. It is not just a desire to clean up its skies which is pushing China to develop renewable energy, says Yu.
Beijing is under pressure from the European Union and others to rein in its carbon dioxide production amid warnings it is likely to overtake the US and become the world's biggest producer of greenhouse gases by 2020, she says.
With coal contributing about 70 percent of China's energy needs, coal- fired power stations are the main culprits behind carbon dioxide emissions and sulfur dioxide pollution.
"The average energy consumption per person is quite low in China - about one fifth of the world's average, but with a population of 1.3 billion the total amount is frightening in terms of the effect on climate change," Yu says.
Beijing also faces pressure to clean up its coal-mining sector given the industry's appalling safety record. Government figures put the number of miners dying on the job at 6,000 last year, although independent estimates are as high as 20,000.
But perhaps the biggest incentive driving China to exploit its sustainable energy resources is to feed its enormous appetite for power. The hunger for coal and oil seems insatiable and soaring oil prices, blamed in part by the International Energy Agency (IEA) on Chinese demand, are also convincing it to pursue other sources of energy.
"A secure energy supply is crucial to China maintaining its economic growth," says Yu.
It is for this reason that industry experts believe Beijing is serious about renewable energy and is on track to be a world leader in sustainable energy technology.
"[The target] is certainly achievable - the issue is more whether the government will get behind it," says Chris Raczkowski, managing director of Azure International, an industry consultancy on sustainable energy.
"But it seems the government is serious - primarily because global energy markets are driving the industry. China does not have good natural resources, except for coal - which makes producing renewable energy attractive.
"Renewables are not a complete solution to its energy problem, but the government sees it as an incremental solution to reduce its dependence on energy imports."
Frederic Asseline, EU manager of renewable energy at the EU-China Energy and Environment Program, says he believes China is committed to greener power.
"This law was passed in record time and it has set the background against which more detailed regulations will be developed," Asseline says.
"This is somewhat atypical for China, where policies and regulations are usually tested first before being incorporated into a wider legislative framework.
"The proposed law has the potential to help China scale up its renewable energy industry in the relatively short term, and ambitious targets have been set by the NDRC [National Development and Reform Commission] for key renewable energy technologies."
The main drive in the expansion of green energy will be wind power and biomass, say experts.
Biomass is produced by burning wood and agricultural waste, either in their original form or by converting them into a liquid fuel such as ethanol first.
"Biomass and wind energy development are the two priority areas to build additional megawatts," says Asseline.
"And the potential for off-shore wind development in China is high."
Raczkowski says: "Many of the big turbine companies [such as Vestas and GE] have their main offices in Beijing and all are talking about localizing their business here.
"Wind is going to be the most predominant in terms of growth - especially in terms of commercial investment from overseas." According to Greenpeace, the Chinese Renewable Energy Industries Association believes the country can develop a wind power capacity of 40 gigawatts by 2020, double its declared target.
This would be enough to meet the needs of around 60 million homes and is more than twice the installed capacity of the controversial Three Gorges Dam once it is finished.
Using wind power instead of fossil fuels to generate that amount of power would cut carbon dioxide emissions by 48 million tonnes - equivalent to all of Norway's emissions in a single year.
The potential is staggering, enthusiasts say. Greenpeace believes China has the capacity to generate 2,000 GW using present technology - four times the capacity of all the country's power stations put together now. Further, Yu says wind power is the way to go because it is more affordable than solar energy.
"The annual growth of wind power has been around 30 percent for the past few years and that's without government help. So with the help of this new law we see wind power as being the answer for China."
With a vast land area suitable for wind farms, China has the edge over cramped European countries when it comes to finding room for thousands of windmills
"It has the most potential, it can be very competitive compared with conventional power," Yu believes.
While initial investments remain high, Greenpeace estimates that with economies of scale and improved technology, by 2020 wind power will be cheaper to harness than burning coal.
Solar energy, Yu says, will be slower to develop because it's more expensive to exploit.
"It's at least twice as expensive as wind power," she says, adding that the technology is not yet there to make it competitive.
Even so, says Asseline, solar photovoltaic (PV) technology in China is growing rapidly.
"The market for PV in China could rapidly become the most important in the world," he says. "China is the world's leader in the production of solar water heaters, for example, which are used to supply hot water to both urban and rural households.
"The total installed capacity in 2005 reached about 70 million square meters of `collector' area. China has a solar water heater production capacity of over 16 million square meters per year."
Photovoltaic cells are also used in remote rural areas to provide power to communities cut off from the main grid and they can be installed on urban rooftops to provide power.
The mainland media reported recently that Shanghai aims to install PV systems on 100,000 rooftops - though that would still only provide enough energy to power the city for just under two days a year.
Taken together, sun, wind and biomass can drive China to become a world leader in renewable energy. "[The] potential is considerable and installed capacity could rapidly surpass levels reached elsewhere in the world with the proper incentives in place," says Asseline.
The key is to attract investment in the sector. Good intentions are not enough.
Beijing must enforce regulations to require power companies to buy a certain proportion of energy from renewable sources and set tariffs to encourage investment in sustainable energy, says Asseline.
The new renewable energy law comes into effect on January 1 and energy campaigners say it is crucial that the momentum for better air is sustained.
Over the next 30 years, China will make up 20 percent of the world's growth in energy demand and half of the increase in coal use, according to the IEA.
As a result, Yu says, it cannot afford to fall short on renewable energy.
If Beijing fails, says Yu, "the cost to the environment and public health will cripple China."
Source: The Standard