cavelamb himself brought forth on stone tablets:
Ernest Scribbler wrote:

"RW Salnick" wrote

Seriously, if a chemical has to be carried onboard and is transformed
thru some process (perhaps even using seawater) to produce the
hydrogen to be consumed in the fuel cell, then what is that chemical,
other than a fuel?



A catalyst.


As with anything associated with the "hydrogen economy", spend some
time researching how these substances are produced.



Never said I thought it was a magical miracle cure. Just asked
whatever became of it.




Try this one.
Very interesting, but no data on the input power budget.


http://www.breitbart.com/article.php...show_article=1

This has already been discussed at length in alt.energy.homepower.

I am confused... is the catalyst comment yours, cavelamb?

Regardless, the following is directed at the respondant who thought that
a catalyst could take the place of an energy input...

This is going to take a minute to set up - please stay with me here...

We are going to substitute gravitational potential energy for chemical
energy in this analogy. Imagine that you are standing in Denver,
looking west at the Front Range. Please imagine further, that behind
the ramparts of the Front Range is a valley at say 8500 feet (Vail?).
Now the tops of those mountains in the Front Range are from 11,000 to
14,000 feet, and you are at 5200' in Denver.

Your position in Denver represents water - dihydrogen monoxide. It is
the low-energy position - the state things want to be in.

To get yourself to Vail (to break apart the water molecule into hydrogen
and oxygen), you need to supply energy. In this initial example, you
need to supply enough energy to crest over the Front Range. You will
get a little of it back, coasting down the west slope of the Front Range
into the valley, but since the valley elevation is still above Denver,
you still have to supply energy to reach this higher energy state.

If you decide to head back to Denver, you first have to supply energy to
get up the west slope, but then you get that energy plus all the energy
it took to reach the valley flor elevation back (you just burned the
hydrogen).

Now imagine you drilled a tunnel thru the Front Range at the valley
floor elevation (the Eisenhower tunnel). Going to or from the valley
doesn't involve any difference in the net energy change between the end
states, but you no longer have to go over the whole front range. The
tunnel is the catalyst. It lowers the energy "entry price" for the trip.

But: there is no possible way to drill the tunnel so that you can travel
from Denver at 5200 feet to the valley floor at 8500 feet without having
to climb at least 3300 feet. The tunnel (catalyst) doesn't change the
net energy produced or consumed by the trip (reaction), it just makes it
easier to get started.

That clean burning hydrogen (2 H2 + O2 - 2 H2O) releases *in theory*
exactly the same amount of energy that it took to break apart the water
to liberate the hydrogen in the first place. *In practice*, it takes
substantially more energy to break apart water than is released by the
combustion.

The challenge to the "hydrogen economy" folks is to explain why if you
have the energy to liberate the hydrogen in the first place, why not
just use that energy directly, instead of throwing away part of it in
making hydrogen.

bob
s/v Eolian
Seattle