Coal may not be the cleanest source of heat, but moving it across China is becoming more environmentally friendly. CGTN's Hu Chao takes us on board one of the nation's busiest railway lines to show how this black substance has a green lining.

The main artery of China's most widely used energy form. The Daqin railway transports hundreds of millions of tons of coal annually. The line stretches 653 kilometers. The name Daqin is derived from its two terminals. One is the coal capital of Datong in northern China's Shanxi Province and the other is the seaport of Qinhuangdao in Hebei Province.

HU CHAO DATONG, SHANXI PROVINCE "The freight trains running on the Daqin Railway can carry up to 20,000 tons in a single trip. They are as long as 2.5 kilometers with more than 200 wagons and pulled by two locomotives, one in the front and the other in the middle. One sudden brake would cause a catastrophic accident. Wagons in the middle would be crushed in seconds. But the operators haven't made any major mistakes in the past 30 years. So what's the secret of their success?"

LIN JIANMIN, HEAD OF HUDONG RAILWAY STATION DATONG, SHANXI PROVINCE "To ensure the train runs quickly and safely, we use domestically-made high-power locomotives and the world's leading technology to carry out simultaneous starting and stopping. And everyone working along the line has also contributed a lot through their hard work."

China has imposed more road transportation bans, where gas-guzzling vehicles still cause environmental concerns. This has increased the need for railway transportation. The annual transport volume of the Daqin railway has risen from an initial one hundred million metric tons to nearly half a billion. Promoting green transportation has also become a priority of this black line.

DONG BIN, SECRETARY OF THE PARTY BRANCH DATONG RAILWAY STATION "First, the whole Daqin railway is electrically-powered. Secondly, we adopted dust-control measures by spraying special gel over the top of every coal pile. And since May we've stopped charging for this to better promote railway transport."

Over the past three decades, the Daqin railway has sent coal to 26 provinces, municipalities and autonomous regions for production and living use. It has fueled fast economic growth across China and aims to contribute more in the future. Hu Chao, CGTN, Datong, Shanxi Province.