Year-long field testing finds electric buses with Toshiba wireless charger cut CO2 up to 60% compared to diesel
17 March 2017
Toshiba Corporation announced the results of year-long field tests of electric buses charged with its wireless rapid rechargeable battery system. (Earlier post.) The tests, carried out with the cooperation of Waseda University, showed that using the buses to replace standard diesel 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 project was supported by Japan’s Ministry of the Environment’s Low Carbon Technology Research and Development Program.
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.
The CO2 emission reduction was calculated by the laboratory of Professor Yushi Kamiya of the Faculty of Science and Engineering at Waseda University using a carbon intensity of L 2.83 kg CO2/l (well-to-wheel) for diesel and 0.406 kg CO2/kWh for electricity.
Recharging was carried out with a magnetic resonance system operating in the 85 kHz band, the proposed international standard. Magnetic resonance was selected as it is more forgiving than 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.
|Overview of the field test|
|Small electric bus||Medium-size electric bus|
|Period||Feb 2016 to Jan 2017|
|Route||6 km||11 km|
|Frequency||4 round trips per day||3 round trips per day|
|Charge time||Approx 15 minutes||Approx 20 minutes|
|CO2 emission reduction||42%||60%|
The SCiB battery installed in the test electric buses is rugged, reliable and has a long life, showing almost no fall-off in performance even after 15,000 quick charge and discharge cycles. It is highly suited for use on shuttle buses operating at locations such as tourist sites and airports, which must combine heavy use with frequent and fast charging.
Toshiba also used the project to verify 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.
I’m convinced that wireless rapid charging system will help boost the use of electric buses. Toshiba will continue research and development of convenient charging technologies and advanced technologies, and contribute to both reducing environment loads and improvement of the quality of urban transportation.—Dr. Osamu Hori, Director of Toshiba Corporation Corporate Research & Development Center