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Thread: : Al Gore - A Generational Challenge to Repower America
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> And as previously stated, why not just rechage your
> electric car, like this
> one: <en.wikipedia.org/wiki/Tesla_Roadster>.
> ~4 hours recharge time gives you a range of some 350km /
> 200 miles.  That's
> prefectly adequate for urban use.  They actually sell
> these things, which is
> one up on the hydrogen cars.  Is there more than one
> hydrogren station (or
> was it two) in the States yet?

It's a dream.
53kWh of battery capacity.
If that 200 miles is at, say, 66 mph then it takes 3 hours
so you have an average of 53/3 =~ 18 kW available.
Do it at 50 mPh and it's an average of about 13 kW. That is,
apparently, adequate for a super modified Lotus Elise
lugging who knows what value of LiIon cells around but it's
far from practical. And the ~ $US100,000 price tag gives an
idea of what it takes to achieve that result at present.

I'm not suggesting that Hydrogen fuelled cars are much more
practical at present. Nor much less :-). But as an example
of what could be achieved practically long term I think
Hydrogen has the inside running at present. LiIon's energy
density compared to hydrocarbon fuels is utterly abysmal.
And its cost is attrocious. And its longevity is laughable.
Choose any three.

Now, if they were talking about Vanadium redox batteries ...
:-) !!!

> BAJ said the infrastructure doesn't exist for the electric
> car (unlike
> petrol), but that's wrong of course.  You're never too far
> from a power
> point.  The downsides to electric are initial cost and
> that slow recharge
> time.

Indeed. The above 53 kWh in 4 hours is about 15 kW input at
good efficiency. At 110 VAC that's about 35A.
At 3 phase 230 VAC per phase that's under 6A per pahse. The
latter is doable, the former will be in some cases. Not
quite a plug into the average wall socket system though.

FWIW, the 53 kWh of energy in the Tesla's batteries could be
provided by under 2kg of Hydrogen. Say make that 6 kg in
practice. Still not nice to store given Hydrogen's low
volumetric density. But potentially doable in a very
practical vehicle.  FWIW.

This page


suggests targets (ha!) of 3 kWh/kg and 2.7 kWh/l by 2015 in
metal hydride storage.
For the above 53 KWh that's ~18 kg and  20l. Half a moderate
family saloon (perhaps not a US one?) gas tank size and as
that includes the tank, no heavier than a half tank of gas.
Lower densities than for petrol, but almost acceptable.
(2010 targets are 50% to 100% worse than this). What does
the 53 kWh battery weigh? How large? What cost?


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Subject (change) : Al Gore - A Generational Challenge to Repower America

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