Electric Power Generation and Distribution

Electric vs Diesel Buses: Wireless Charging Cuts Emissions

17 March 2017

Results of year-long field tests of electric buses charged with Toshiba Corporation’s wireless rapid rechargeable battery system show significant reductions in carbon dioxide emissions. The research, conducted with Waseda University in Japan, showed that using the buses to replacing standard diesel with electric buses could cut CO2 emissions from daily operation by up to 60% for a medium-sized bus and by up to 42% for a small bus.

The Toshiba contactless charger.The Toshiba contactless charger.

For the field test, Toshiba developed a 44kW wireless rapid rechargeable battery system that feeds power to the battery when the bus is parked over charger pads. The buses were customized to run on Toshiba’s SCiB rechargeable batteries (52.9 kWh pack for the medium-sized bus), and provided regular service between All Nippon Airways facilities in Kawasaki and vicinity of Haneda Airport in Tokyo for the year from February 2016 to January 2017.

Recharging was carried out with a magnetic resonance system operating in the 85kHz band, the proposed international standard. Magnetic resonance was selected over electromagnetic induction, which requires close alignment and small separation of the charge transmitting and receiving pad. The charge pad in Toshiba’s system can be misaligned by as much 20 cm along its width and 10 cm along its length, and the two pads can be as far apart as 10 cm.

The long-life batteries displayed almost no performance fall-off even after 15,000 quick charge and discharge cycles. The research also confirmed that a light-duty EV equipped with a wireless battery charge receiving pad could be efficiently charged by the same charging system as the bus.

To contact the author of this article, email sue.himmelstein@ieeeglobalspec.com


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