World's first hydrogen-powered tramcar rolled off the assembly line in Qingdao on March 19, 2015. [bandao.cn]

World's first hydrogen-powered tramcar rolled off the assembly line in Qingdao on March 19, 2015.

The new tram is the only hydrogen powered vehicle in the field, and makes China the only country in the world to have mastered the technology.

Hydrogen fuel cells are a new clean energy source, widely used in the automobile industry, but lagging behind in the field of rail transit.

Liang Jianying, chief engineer of Sifang Co., a wholly-owned subsidiary of China South Rail Corporation (CSR), said it took two years for Sifang to solve key technological problems, with the help of research institutions.

The tram can be refilled with hydrogen in three minutes and can then run for 100 km at speeds as high as 70 km per hour.

No nitrogen oxides will be produced as the temperature of the reaction inside the fuel cell is controlled under 100 degrees Celsius. Water will be the tram's only emission, Liang said.

Each tram has over 60 seats and can carry more than 380 passengers.