> > Those people making hydrogen in vehicles by cracking water are nuts.
> 
> I'm so glad you weren't advising the Wright Brothers 104 
> years ago Tony :) 
> 
> > it somehow has more energy than you need to crack it?
> 
> How much energy did it take to build the Tacoma Narrows 
> Bridge... and how much to destroy it?
> 
> I believe the secret to hydrogen on demand is teasing the 
> hydrogen-oxygen bonds apart using resonance.
> 
> > BTW, good job getting an 'evil oil company' story in early  :)
> 
> Is there a non-evil one? :)
> 
> Nigel


I don't mind people doing things that are generally considered nuts, like
solar sails, kilometer high chimneys (turbine of top to catch updrafts), hot
rocks, or Russell's He3 lunar miners.  These at least have a chance of
working, the real winner (eventually) will be He3 fusion.  Sure, hydrogen
may work, but cracking water to get it is nuts.  In a car is especially
nuts.

Let's compare energy densities, MJ per litre (so volume, not weight):

Helium fusion       - 8,570,000,000,000,000,000,000,000
U-235 fission       - 1,700,000,000
Petrol              - 34.6
Liquid hydrogen     - 8
Compressed hydrogen - 4.7
Li-ion battery      - 1.5
Lead-acid battery   - 0.15
Hydrogen gas        - 0.01079
Water               - 0

Go water!  Oh that's right, it's a waste product, not a fuel.  Dang, get the
jumper leads ma, let's get cracking.  A litre of water gets us about 1000
litres of H2, so 11MJ of energy there.  

Ok, a litre of petrol will propel the average car about 15km (35 mpg?).
Assuming identical efficiencies, liquid hydrogen about a 1/4 of that, and as
for the 1000 litres of H2 gas... about a 1/3rd, not too shabby.

One source claimed it takes 10kWh (36MJ) to crack a litre of water.  So
you're turned 36MJ into about 11MJ... and you haven't started the engine
yet.

To match a litre of petrol, you need around 3,000 litres of hydrogen gas.
Ha, you say, 3 cubic metres is nothing!  Just look at all those little
bubbles...

Yeah, I know, "They laughed at Galileo etc".  They also laughed at Bozo the
clown.  How come no-one ever says "They laughed at Edison etc"?

Speaking of laughing, have another look at Keelynet.  The 'pour water on
aluminium' method gets a couple of mentions, in summary - 'it sucks'.
That's hilarious, something that actual produces a decent amount of hydrogen
(with a few drawbacks), and Keelynet thinks it sucks.

Tony

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