Following Chinese Premier Li Keqiang's promise to "make our skies blue again" at the start of this year's top legislative meetings, Beijing has shut down its last large coal-fired power plant.
The capital has long pledged to improve air quality by reducing the use of coal, which produces fine particles when burned that are crucial to the formation of smog.
Beijing is therefore dependent on supply from coal-fired power plants in the neighbouring provinces of Hebei and Inner Mongolia, where environmental regulations are not enforced so strictly.
Despite being shut down, one coal-fired unit will be maintained, as it serves as the only backup unit for the city's winter heating system.
Following its closure on Saturday, emissions of 1.76 million tonnes of coal, 91 tonnes of sulphur dioxide and 285 tonnes of nitrogen oxide will be reduced annually, state-run agency Xinhua reports.
The Huaneng Beijing Thermal Power Plant's final unit suspended operations on March 18, marking the end of coal-fueled generation in the city.
However, Beijing, with more than 30 million residents, can not not produce enough power to meet its own energy demand. And just like that, Beijing became the first Chinese city to rely exclusively on cleaner energy sources - including natural gas and wind farms - to generate electricity and heating. Its five generator arrays, with a total energy capacity of 845 megawatts, burned more than 8 million tonnes of coal per year.
According to Cai, a new power plant is now being built and will rely only on natural gas.