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China has built the world's most powerful hydrogen-powered locomotive. It could replace trains that use fossil fuels.

The "Ningdong", China's first hydrogen locomotive converted from a normal engine, rolled out of the factory on Thursday.

Liang Zhenzhong, chief engineer, says the hydrogen-powered train could run continuously for up to 190 hours. 

He says the locomotive has a hydrogen storage system that could be refilled in two hours. It is also cheaper to operate. 

"Hydrogen is a clean, renewable energy. The operating costs of hydrogen-powered locomotives are half those of normal ones," he says. 

Unlike fossil fuels, hydrogen does not produce harmful air pollution or greenhouse gases.