China's capital city is doing something huge about its perennial pollution issue.

Almost 70,000 petrol powered taxis in Beijing will gradually be replaced with electric vehicles, and any new taxis on the road must be electric, according to a report by the National Business Daily.

The project to replace all the current petrol powered cars is estimated to cost taxi operators $1.3 billion (9 billion yuan).

Some 67,000 of Beijing's 71,000 taxis currently run on petrol.

A conventional car is estimated to cost around $10,000, with an electric vehicle double that amount, at $20,000.

Electric cars have a smaller carbon footprint than conventional cars, which would help reduce CO2 emissions in Beijing.

Beijing and its surrounding states suffer greatly from crippling pollution, thanks to the heavy industries up north. Earlier this year, Beijing cancelled dozens of flights at its airport and suspended buses due to heavy smog -- and issued a pollution "red alert."

According to a study in 2015, air pollution is killing about 4,000 people in China each day.

Needed urgently: Charging stations

However, the energy-efficient cars may bring with them new problems.

When Beijing in 2014 added some 200 electric taxis to its fleet, drivers complained that there were queues of up to six hours at electric charging stations.

"There are 200 electric taxis on the streets of Tongzhou in Beijing, but only about 100 are on the road, while the other 100 are waiting to be charged," a driver told business paper Caixin.