middle east

[Mike O'Dell]

in my day job, i've been spending a lot of time looking
at various "energy system" topics with alternative power
trains being a biggie.

hybrids like the Toyota Prius get essentially all their gain
from regenerative braking.  it takes a lot of energy to
accelerate that mass up to 35-40mph, and most cars promptly
turn it into heat when it's time to stop. regenerative braking
is "energy recycling" - pull the kinetic energy back out
as electricity, and then use it again to re-accelerate after the stop.

the really tricky part, though, is that batteries won't do this.
they charge too slowly and they return only about 60% of what
you put into them (and those are *really* good batteries).

this is where ultracapacitors come into the picture.
Ultracaps easily absorb the electrical energy produced
by regen braking, and then they give 99% of it back,
and as anyone who has blown the tip off a screwdriver
discharging a big cap knows, they can give it back in
a big hurry (ie, power as well as total energy).

Maxwell is the current king of the hill in ultracaps,
although this is an area where lots of work is happening
in real time. there was just a major conference at
U of Maryland on ultracaps and related topics.

http://www.maxwell.com/ultracapacitors/products/quickturn.html

the amusing spec reads:

	650 to 3,000 FARADS

and working voltages up to 540VDC depending on capacitance.

that would send the end of your screwdriver into your next lifetime.

	-mo


	

Alex Fraser wrote:
>     A good use for regenerative braking. Electricity generated by 
> braking is doubly efficient and you can avoid the drag of the panel.  
> Anyway I believe most cars these  days suck down a lot of amps running 
> all the electronics needed for a modern engine to function.  Could a 
> small panel provide the juice? I think a good place to jump in the train 
> is the first U joint after the transmission. On the up power side it 
> would be in a fixed location relative to the tranny so power take off 
> would be mechanically possible with a pulley (if you bolt the alternator 
> to the tranny/engine).  Seems you could wire the voltage regulator right 
> to the brake peddle (brake light switch?) which would simplify control.  
> Under engine power you would freewheel the alternator. You would 
> generate juice only when braking. How could you calculate pulley size?
>     I think we have a lot of "Iron" on our roads.  Stop gap measures 
> will be needed till we can retool. Hams know some electricity and most 
> certainly have a  history of tinkering, which puts us in a good position 
> to help.
> 
> 
> Robert Bruninga wrote:
>>>>> Alex Fraser <beatnic at comcast.net> 07/14/06 12:10 PM >>>
>>> Anyone on list running on vegetable oil?
>>
>> No, but I would like to join a list on do-it-yourself
>> electric and alternative cars.  I'd love to find a source 
>> for shortened autombile fan belts so I could remove
>> my alternator and just charge the battery on sun
>> power.  Would save 2 or 3 MPG...
>>
>> $4 gas, global warming,... the end is near...
>>
>> de WB4APR, Bob
>>
>>
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>>
> 
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