BEIJING — China has pushed the use of cleaner fuel for winter heating in northern China, where coal burning is a major source of air pollution.

Since the end of 2016, China has been encouraging the use of natural gas and electricity instead of coal for winter heating. The country also fostered the development of clean energy such as geothermal, solar and nuclear energy to ensure low emissions and low energy consumption.

The clean energy for winter heating in northern China accounted for 50.7 percent by the end of the last heating season, up 12.5 percentage points from 2016.

The share of clean energy for winter heating is expected to rise to 70 percent by 2021 and replace 150 million tons of coal, according to an official plan.

Clean heating is the key measure to improve air quality in Beijing, Tianjin, Hebei province and surrounding areas, which contributes more than one-third of the reduction of PM2.5 concentration, said Liu Youbin, a spokesperson with the Ministry of Ecology and Environment.