APR 15

Much has been made of the potential of ultracapacitors in electric cars. Many start-up companies are hoping to make the big breakthrough that changes the future of EVs by creating lighter, cheaper and better energy storage, but so far we haven't seen the results.

German company MAN has decided to look beyond small electric vehicles and has outfitted a hybrid bus with an ultracapacitor. Paris's public transport system RATP is currently testing a few of these models called Lion's City Hybrids in the city without passengers to see if they're worth permanently adding to their transportation fleet.

The bus is being tested on four different bus routes to gauge its performance under various demands like longer distances or more frequent stops. The ultracapacitor allows the bus to start without turning on the engine. Once the bus is moving, the diesel engine starts running.

MAN claims that the hybrid bus reduces fuel use by 20 to 25 percent compared to the currently-used models. If these test go well, this could be the beginning of ultracapacitors finally making their way onto the road instead of just being an exciting prospect.

via Autoblog Green

Comments (8)

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written by Edwin, April 15, 2009

The article made no mention of whether or not the buses "without passengers" were loaded with what is the normalized average passenger per mile equivalent load weight. If not, then the tests won't give an accurate picture of the possible fuel savings.

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speed vs. efficiency
written by Steve, April 15, 2009

My understanding of ultracapacitors is that they're just better suited than batteries for rapid charge and discharge, which is consistent with the way a vehicle moves (e.g. rapid starts). Maybe someone with a physics background could explain why this might reduce a hybrid's fuel consumption?

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brief on ultracaps
written by Sean, April 15, 2009

So, my understanding is this. Since a bus makes frequent starts and stops it will help. When starting, an engine is required to provide a great deal of torque (especially when weights). Ultracaps can discharge very quickly thus providing plenty of POWER (not energy) to an electric motor to create this torque. Then when stopping by using the brakes, the braking mechanism can be using the momentum to turn a generator (perhaps just the motor acting in reverse). The Ultracaps can also charge very quickly thus accepting a larger ammount of the energy at a higher charging rate(power) than traditional batteries can accommodate.

Seems like a great idea since busses are already large and carry plenty of weight. That is the downfall of Ultracaps, they don't store a lot of ENERGY so they can discharge fairly rapidly... esentially the gas engine could primarily be used for cruising, which I believe is where it's most efficient anyways (hence highway mpg is greater than city mpg)

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written by Bob, April 16, 2009

Sounds great.. maybe in future we won't see huge plumes of smoke coming from the back of buses and trucks. I imagine that the fuel savings will be quite great.

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ultracapacitors
written by hyperspaced, April 16, 2009

Theoretically, they are ideal for transportation you said before. My 2 cents as a physicist is that ultracapacitors are able to accept more current (generated from braking) when charging instead of LiIon batteries which implement special circuitry to avoid damaging to the battery cells.

I am quite skeptical as we really haven't seen any real breakthroughs in ultracapacitor technology

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ultra caps + li ion + diesel
written by nuvi, April 16, 2009

I think that adding ultracaps to capture braking energy, to a plugin hybrid bus that has the batteries storing energy to provide baseload energy would save you a ton of gas.

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written by Blog en Commun, April 21, 2009

Tks to say your source for the picture

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written by Fred, July 28, 2009

sounds difficult, always remember something good may be eliminated to adjust to weight and making it lighter

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