Beijing plans to build four natural gas power-generating stations by the end of next year to replace coal-fired plants, the municipal government said.

The initiative is expected to cost $7.8 billion, the state-run Xinhua News Agency reported Monday. The switch to gas, says Beijing's Municipal Commission of Development and Reforms, will reduce sulfur dioxide emissions by 10,000 tons.

The new plants will generate 7.2 gigawatts of power.

The four existing coal-fired power plants now have a total generation capacity of about 2.7 gigawatts and burned 9.2 million tons of coal in 2012, accounting for 40 percent of Beijing's total coal consumption. The plants will be closed when the gas-fired facilities are operational.

Last month, Beijing pledged to reduce the city's coal consumption by 8 million tons a year by 2015 and 13 million tons a year by 2017, in an effort to reduce air pollution. Last year, Beijing's total consumption of coal was 23 million tons.

Beijing has grappled with recurring bouts of severe levels of smog.

On Sunday, Beijing's air quality index registered higher than 300 -- or "severely polluted," the highest level on Beijing's Municipal Environmental Monitoring Center's six-level scale.

Xinhua reported that early Sunday Beijing traffic police closed six major inter-provincial expressways, amid the peak of travel as China's weeklong "Golden Week" national holiday came to an end. Visibility at Beijing's Capital International Airport was just 820 feet to 1,640 feet, with 44 percent of departing flights delayed or cancels and dozens of incoming flights redirected.

Ma Jun, one of China's most well-known environmentalists and director of the Institute of Environmental and Public Affairs, a non-profit group in China that works on environment, pollution control and sustainability issues, said there is a link between smog and climate change.

"Much of these two problems have a similar source, fundamentally it is our energy source that is predominantly dependent on coal," Ma was quoted as saying by The Guardian newspaper Monday. "That is the source of the problem for our local smog problem and also for our climate change contribution. We need to deal with the coal issue."

China, the world's biggest consumer of coal, has accounted for 82 percent of the increase in global coal consumption since 2011, says the U.S. Energy Information Administration.

China is also the world's largest emitter of greenhouse gases.

The Chinese government last month said it aims to cut total coal consumption to below 65 percent of its total primary energy use by 2017. That compares with about 67 percent last year.