Eliminate the need for charging infrastructure entirely and reduce your upfront costs. Call it a Pruis bus.
In most downtown urban areas the bus routes used do not exceed 40 mph so power the bus accordingly when building it. Most buses are over powered for the low speeds they operate at in urban traffic.
It’s a light-train on wheels. Does that make it a bus? a train? It’s unclear. But the developers of the AutoTram at the Fraunhofer Institute seem to have hit upon an interesting way of powering public transportation.
While electric vehicles usually run on single charges, the AutoTram travels on its route between charging stops, where it powers up for 30-second intervals.
“We wanted it to be flexible and rather cheap like a bus system–less expensive than light rail. One way we achieve that is not to have any overhead line, or rails,” said Ulrich Potthoff, head of the transport department at the Fraunhofer Institute.
In developing the AutoTram, researchers developed a mix between a battery and a “super-capacitor,” which gives the vehicle large-scale, short-term power storage capacity.
The AutoTram’s range is decidedly small. Developed in Dresden, Germany, it can travel 1.2 miles at a time before reaching a charging station and getting a 700-volt jolt of power. While its developer argues that distance is more than enough to cover the distance between stops in most urban centers, a diesel electric generator is on reserve should anything go wrong.
Potthoff explains that his team decided against using the widely accepted lithium-ion batteries, found in traditional EVs, because in addition to being heavy and expensive, most of those batteries have only a limited number of charges in them (1,000 at most, Potthoff argues). The AutoTram’s hybrid power storage system would allow for significantly more charges over a lifetime, Potthoff said.
The finalized version of the AutoTram - which should be completed next year - would run 30 to 50 percent cheaper than light rail over its lifespan, but would be nonetheless more expensive than diesel buses. Despite the higher costs, though, the AutoTram might be a viable solution for cities hoping to substitute the visual pollution of overhead street lights for a cleaner, wireless system.
Photo: Fraunhofer
via [Fast Company]
