In article <U8KE6.19884$bA2.5112957@typhoon.ne.mediaone.net>, Cindy
Andrews <cinbad@mediaone.net> writes
>> Imagine you have a car with fuel cells in it which
>>powers the wheels thru electric motors.
>
> How else would a fuel cell drive a car?
>
Well, you didn't seem to know much about anything else, so I thought I'd
make it obvious....

>> The ideal solution is for intermediate hybrid cars which use a petrol or
>> diesel engine to drive a generator, which powers the wheel motors (and
>> stores power in a battery for stop-start loads). This will do away with
>> heavy transmissions, give perfect 4WD, be much more efficient
>
> The ideal solution would be to have a small motor running at perfect
>efficiency, i.e. at one constant rpm, driving a generator & negating the
>need for any transmission at all.

No it wouldn't - such engines STILL produce far too many emissions,
compared to the pure water output of the fuel cell.

> Incidentally, this would be far from
>"perfect 4WD".

Oh yes it would, If you have a DC motor of the series-wound type built
into each wheel, and driven from the same power source, you get perfect
weight distribution in the vehicle, and equal torque is applied to each
wheel. If one wheel loses traction, and starts to spin, the rising back-
emf due to this REDUCES the drive current to that wheel - while NOT
AFFECTING the other 3 wheels torque at all. Sooner or later, the reduced
drive current causes the errant wheel to stop spinning - and traction on
all 4 wheels is restored.

But you could have 3 wheels spinning on the ice, and the 4th one STILL
would have full torque - unlikely with "normal" 4WD arrangements.

Hard to get more perfect than that - how would you improve on it?

This arrangement does away with prop shafts, gearboxes, differentials,
limited-slip arrangements, ABS braking arrangements, etc.

The weight saved and complexity reduced is amazing.


> Nickel-metal hydride cells are getting cheaper, and are
>smaller, lighter & much better than lead acid or nickel cadmium cells for
>vehicle use, and other, better technologies are being developed as we speak.
>(or type)

True, and all these can be used on vehicles to smooth out the power
demands of the vehicle so that they can be supplied in the short term by
the sort of constant-speed engine you describe, and in thel ong term by
fuel cells.

The problem with the engine solution you suggest is that, being a
Carnot-cycle engine, as all internal combustion engines are, it has
inherent efficiency limits.


Being a reciprocating engine, it also has noise, vibration, oscillating
parts, etc that also contribute to inefficiencies.

AND, using explosive combustion,. it will ALWAYS produce far more
pollutants than a fuel cell. AND produce them in the local area where
the vehicle is, in a distributed manner.

Fuel cells, on the other hand, produce only water locally.

And they don't have the efficiency limits of a Carnot-cycle engine, and
are noiseless and vibrationless.

Yes, you have to provide the hydrogen, which COULD, as you say be done
by grid-distributed electricity using electrolysis.

However, it can be produced by other means, including reformed natural
gas, where there is a carbon byproduct. But, treated in a central plant,
this carbon could be locked up and disposed of in a number of ways.


Or, perhaps, it can be produced soon by solar electrolysis, rapid
progress in which is being made as we speak.

The constant-speed engines you seem to love unfortunately produce carbon
in carbon dioxide form as an inevitable consequence of operation on any
fuel other than hydrogen. They spew it out wherever the vehicle happens
to be running, and you're back to the original problem.

I will; agree that they are the ideal intermediate step, and should be
used to help perfect and reduce the cost of all the other components of
a hybrid vehicle - the wheel motors, short-term storage batteries,
electronic regenerative braking systems, electronic power controls, etc
etc.

Then, when these have become the norm in vicle production, the
troublesome, noisy, unreliable, and polluting infernal combustion engine
can be replaced by the fuel cell.

>
> Fuel cells have their place: in spacecraft, and in homes for backup power
>generation, but their use in any vehicles (with the possible exception of
>public transportation) is not in anyone's best interest but the oil
>companies.

Rampant nonsense.

How does a fuel cell in a car become a slave to the oil companies and
the reciprocating engine you think is the answer NOT do so, when it
uses the products of the self-same oil companies?

The sooner the infernal-combustion engine is outlawed, the better.

It's a noisy, dirty, polluting vibrating lump of junk - a 19th-century
technology - llike suggesting we all heat our homes using open coal
fires. (another 19th-centruy technology).


- Rod Buck

View index by [date] [author] [subject]
Previous message: Re: prestidigitation, misdirection, and puzzled peasants, Cindy Andrews
Next message: Re: VG ?, ECI Sys
Next message in thread: Re: prestidigitation, misdirection, and puzzled peasants, Robert W. Cunningham
Previous message in thread: Re: prestidigitation, misdirection, and puzzled peasants, Cindy Andrews