Ultracapacitor Buses Work... As Long as You have Lots of Quick-Charge Stations


Photo: Sinautec Automobile Technologies
Ultracap Breakthrough Still Desperately Needed
Ultracapacitors have just the right characteristics for electric vehicles (very fast charge and discharge, unlimited number of cycles, etc) except that they don't (yet?) hold enough electricity to give an EV the kind of range that most people are used to. This doesn't mean that they are useless in the transportation sector, though. SINAUTEC and Shanghai Aowei are testing ultracaps in electric buses, but it only works since the buses have very predictable routes and need to stop regularly, allowing oppotunities for quick recharging.
This is the hybrid version, which also uses ultracaps. Photo: Sinautec Automobile Technologies

Sinautec's forty-one seat Ultracap Buses have been serving the Greater Shanghai area since 2006 without any major technical problems. They claim that even if they were powered by the dirtiest coal plants around, these buses would still emit 1/3 of the CO2 that diesel would emit (and even less with cleaner electricity, of course).

Here's how it works:

The trick is to turn some bus stops along the route into charge stations, says Dan Ye, executive director of Sinautec. Unlike a conventional trolley bus that has to continually touch an overhead power line, Sinautec's ultracapacitor buses take big sips of electricity every two or three miles at designated charging stations, which double as bus stops. When at these stations, a collector on the top of the bus rises a few feet and touches an overhead charging line. Within a couple of minutes, the ultracapacitor banks stored under the bus seats are fully charged. [...]

Ye says the buses use 40 percent less electricity compared to an electric trolley bus, mainly because they're lighter and have the regenerative braking benefits. They're also competitive with conventional buses based on fuel savings over the vehicle's 12-year life, based on current oil and electricity prices. Sinautec estimates that one of its buses has one-tenth the energy cost of a diesel bus and can achieve lifetime fuel savings of $200,000.

This sounds good, but looking at the technical specs below, it's obvious that the limits in range and speed are probably still too restrictive for most cities. But most new technologies start this way. With some incremental improvements (which are already happening), this could become very practical and it wouldn't be surprising if in the near future we saw some electric buses using ultracapacitors instead of heavier and more expensive chemical batteries.

Via SINAUTEC, Technology Review
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Tags: China | Electric Cars | Electric Vehicles