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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.'"
We have trams (light rail) here in Melbourne. Maybe if you ran the numbers you could take away the overhead cables from most of the network and just charge the trams at stops and intersections. Might be cheaper overall that way.
http://michaelsmith.id.au
nice tin foil hat.
Here's a real world example http://greentransportandenergy.blogspot.com/2009/03/great-importance-of-wheel-motors.html
They had a working prototype, they approached Detroit to get their making-cars expertise... and the project gets quickly scrapped for no apparent reason.
You can't take the sky from me...
The cap's are under the seats?! Call me old fashioned (and it won't be the first time) but I'll take a cab, thank you.
"You can't get people to sit over an explosion."
--Colonel Albert A. Pope, 1890s bicycle and electric car mogul, on the newly introduced internal combustion engines.
So what they need to do is reduce the weight of these independent motors, or find a way to place the suspension within the wheel assembly itself. Some kind of circular leaf spring assembly comes immediately to mind. Imagine a wheel axel, surrounded by springs rather than hard 'spokes' that connect it to the rubber.
Kind of a 2 state suspension system with a small leaf spring system between the actual rubber and the motor, and then a heavier duty suspension between the axels and the rest of the car.
http://www.utexas.edu/research/cem/Energy%20Storage%20Composite%20Rotor.html
The University of Texas at Austin Center for Electromechanics (UT-CEM) has developed a 2 kW-hr flywheel battery for energy management on a hybrid electric urban bus. The battery will recover braking energy and store excess energy generated by the prime mover. The flywheel rotor, fabricated from high-strength composites, spins at 36,000 rpm at full charge (~825 m/s tip speed), and is housed in a vacuum enclosure to minimize windage drag. A cross-section of the flywheel system design is shown. Ensuring flywheel safety is a major issue that must be addressed in using flywheels for transportation applications. In support of this activity, the durability tests performed under Phase IV of the DARPA Flywheel Safety Program, focused on this flywheel design.
Muchas Gracias, Señor Edward Snowden !
as a engineer having worked on mining trucks for 12years with wheel motors, that page seams very guilty of avoiding context. Komatsu (mostly GE), Liehbier (Siemiens+GE), and Caterpillar all have wheel motored mining vehicles in production. 1) They show no gearing reduction, electric motors are generally very in-efficient at high torque, they mostly run at around 40:1 reduction in real world car app, this kind of gearing reduction is very pricey to create for high torques without lots of space. 2) Electric motors require a very large current to produce those torques (especially if no gearing reduction) and/or lots of windings (lots of weight) big wiring, and difficult power supplies 3) they show no room for excitation of the rotor, this means permanent magnets = rare earth magnets = $$$ + dense weight. 4) very small bearing surface area, lots of spinning mass = lots of momentum = lots of torque when turning, bumps, etc. Front wheels sounds like a very bad idea. 5) single efficiency number is suspicious, as stated above torque is poor efficiency, I do believe the efficiency at higher speeds but not at high torque. 6) sealing against weather/dirt/mud. Even if they get only 4% loss, good luck with cooling that and sealing it at the same time, without dumping the heat into the tires which will already be under trouble (see the suspended weight = extra tire abuse) 7) still no economical battery choice that can make electric cheaper than diesel over the lifetime of a battery.
That said, I want 2 for my 1970 2WD truck. It has room for them, and I could slap them on get regen braking, and emergency 4WD help. I don't need much help, and since 80% of braking energy is slowing from 75mph to 25mph so I don't care about the torque/efficiency from 25 to 0.
I actually asked a fellow I know who works at Tesla about wheel motors. He basically said it's a bad idea from a performance and handling point of view. The additional weight in the wheels makes the suspension less effective and means that the effect of going over a bump will be a lot harsher. Besides, he said it also would add a lot to the cost since now instead of one motor you need two or four, as well as two or four inverters and a lot more complicated control software. This also would add more weight since each motor needs its own set of magnets and housing. Cooling can also be a problem. It's much cheaper to just use a differential and axles which typically have very little loss with the advantage that the weight is shifted to the car body. It also makes it easy to do things like water cooling for the motor. I suppose one could still use multiple motors located in the body and use axles to get rid of all of the mass in the wheels, but it still adds a lot of unnecessary complexity to the control system and additional cost and less reliability.
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