The first test of a commercial electric train using superconducting cables suggests that the technology could help a typical urban rail network to save an average of 5% in energy.

Most electric railways in urban centres suffer from voltage drops because of power losses as electricity is transmitted along the line. To reduce these losses, Masaru Tomita and his colleagues at the Railway Technical Research Institute in Tokyo designed a superconducting cable to send electricity from substations to trains. A 310-metre-long section of the cable improved the energy efficiency of a two-car train on a test track, and a 6-metre section tested on an operational commercial line successfully transmitted electricity to a three-car train running at its normal speed.

If implemented globally, superconducting cables could reduce carbon dioxide emissions by 327,000 tonnes annually, the authors estimate.

Energy 122, 579–587 (2017)