Alstom, a French rail company, has developed the world’s first hydrogen-fueled, zero-emission trains. The fleet, called Coradia iLint, is set to undergo testing as early as this month and continue throughout next year.

The trains convert hydrogen into an electric power source for the locomotives and, as a result, only emit condensation and steam. This conversion process happens in the rooftop tanks, where hydrogen is housed and later converted, with the addition of oxygen from the air, into electric power.

CityLab wrote that this fleet’s fuel source may fall into the carbon-neutral category due to the fact that the hydrogen used is a waste product from the chemical industry.

The trains use lithium batteries that store excess energy into a back-up fuel cell. Alstom claims that the trains, as the first of their kind, have tops speeds of 87 mph and enough storage to make just under 500-mile journeys.

According to Dezeen, the fleet of clean energy trains could begin service in Germany as early as December 2017.