It is believed to be the first urban train service in Japan to entirely operate on renewable energy and as such is powered by geothermal and hydraulic power supplied by the Tohoku Electric Power Co. group.

The Setagaya Line, which is 5km long and connects Sangenjaya and Shimotakaido stations, regularly carries an average of 115,000 passengers a day, which resulted in 1,065t of carbon dioxide emissions in 2017. That figure thanks to the use of geothermal energy will now be zero.

An official for the train operator said: "We are aiming to create a low-carbon and recycling society, we will make efforts to promote the wider use of renewable energy." a Tokyu official said.

Carbon dioxide emissions from the Setagaya Line totalled some 1,065t in fiscal 2017. The use of renewable energy will reduce the figure effectively to zero.