Electric buses have been around a long time, but until recently they’ve been more like bumper cars than real electric vehicles. To run networks, cities either erected extensive overhead wiring (like in San Francisco) or, in some cases, put third rails in the ground. Both methods required constant contact between the bus and the power source, hefty investment, and still came with drawbacks, including tangles of unsightly cables.
The new trend is to disconnect the electric bus from the power mothership, either by installing batteries or fuel cells, or by employing different types of electric charging. Several European operators are now setting up “flash charging” systems, where buses get short jolts of juice while they set down and pick up passengers. Backers of the technology claim it gets around disadvantages of other types of transit, including pollution and clutter issues.
For example, Berlin will shortly begin using flash charging on one of its central routes. Buses on the four mile line will top themselves up from big metal pads installed underground. At the beginning and end of trips, a “pick-up coil” on the underside of the bus lowers down until it’s close to the pad in the road. Power is transferred “inductively” or through an electromagnetic field.
Because the route isn’t very long, there are no intermediate charging points, though this would be possible if needed. Each flash actually restores only 20% of the battery, because that’s all that’s required for about 12 miles of travel time, according to Johanna Strunk, a spokesperson for Bombardier, the company behind the system. The bus is 12 meters long and holds 70 people, the same as conventional diesel vehicles in Germany’s capital.
“The vehicles charge more often for a short time rather than fully discharging the battery and then being forced to stop for a long time to recharge,” she says in an email. “This concept guarantees maximum battery lifetime while reducing the battery size to a minimum.”
The big question, as ever, is price. The Canadian company says total cost of ownership is “slightly” higher than for diesel buses. But it’s confident that prices will become more equal as manufacturing scales up.
Having said that, cost isn’t the only reason cities might want such a system. Of course, it also reduces particulate and carbon pollution, produces less heat than a conventional engine, and isn’t as noisy. Those are all quality-of-life issues that are worth taking into account alongside the hard economics.