Berlin,  Almost four years after the start of trial operations, the world's first passenger train network powered by hydrogen was launched in the German federal state of Lower Saxony.

The 14 trains with hydrogen fuel cell drive produced by French manufacturer Alstom are to replace diesel trains, Xinhua news agency quoted the local transport authority of Lower Saxony, LNVG, as saying on Wednesday.

Five of the new trains are already in operation, with the others to follow by the end of the year.

"This project is a role model worldwide," Lower Saxony's Minister President Stephan Weil said. "As a state of renewable energies, we are thus setting a milestone on the path to climate neutrality in the transport sector."

During two years of trial operations, two pre-series trains "ran without any problems", the LNVG noted.

The total cost of the project is around 93 million euros.

The Coradia iLint emission-free hydrogen fuel cell trains have a range of 1,000 km, enabling them to "run all day long on just one tank of hydrogen", Alstom said in a statement.

The trains will save 1.6 million liters of diesel and thus reduce CO2 emissions by 4,400 tonnes per year, according to the LNVG.

The train has a maximum speed of 140 km per hour.

"We will not buy any more diesel trains in the future," LNVG spokesperson Dirk Altwig told Xinhua.

Other older diesel trains in use must be replaced next. The company has yet to decide whether to operate hydrogen or battery-powered trains.

Germany aims to reduce greenhouse gas emissions by 65 per cent by 2030 compared to 1990 levels.

Climate neutrality should be reached by 2045, five years earlier than originally planned.