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Ultracapacitor Bus Recharges At Each Stop
TechReviewAl writes "A US company and its Chinese partner are piloting a bus powered by ultracapacitors in Washington DC. Ultracapacitors lack the capacity of regular batteries but are considerably cheaper and can be recharge completely in under a minute. Sinautec Automobile Technologies, based in Arlington, VA, and its Chinese partner, Shanghai Aowei Technology Development Company, have spent the past three years demonstrating the approach with 17 municipal buses on the outskirts of Shanghai. The executive director of Sinautec touts the energy efficiency of this approach: 'Even if you use the dirtiest coal plant on the planet [to charge an ultracapacitor], it generates a third of the carbon dioxide of diesel.'"
He meant Unsprung Weight, or the weight of the wheel and suspension and associated components. http://en.wikipedia.org/wiki/Unsprung_weight
Most caps can store charge for months or even years. They can store both high current and high voltage, but cannot deliver a sustained current. In that respect they're a bit like a high pressure air tank, where the gas doesn't change state to a liquid in the tank. (like CO2 does, those are called "constant air" tanks, and are more akin to lead acid batteries because they maintain their pressure until almost exhausted) Like an air tank can retain pressure for months without significant loss as long as there's no leak, so can capacitors.
I work on HV equipment and am all too aware of how capacitors (and things that behave like them... picture tubes in particular) can retain several hundred volts (life threatening) of power for months. Always have to discharge them before working on them, even if they HAVE been unplugged for a month.
Buses I've been on aren't known for their air conditioning anyway. When the bus is idling in a jam it's just sitting there and consuming almost zero of its power reserves.
I work for the Department of Redundancy Department.
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