>> Most of the statements made below are a result of a
>> misundertsanding, genuine or contrived, on the part of 
>> the
>> writer.
>> Substitute the word "battery" in most cases and the
>> obviousness of the statements will become true. Perhaps
>> reword somewhat for the technology in use.

> I don't think that it is possible to compare hydrogen to a 
> battery in such a
> direct way.

You can. They are directly comparable. In both cases and 
energy source is used to "charge" a medium or store energy. 
In all comparable by energy storage by chemical reaction and 
using molecular bond energy. NimH, LiIon, LA, H2, .. .
In the case of H2 you could use eg a fuel cell as the output 
device to make the comparison more obvious. You could also 
build the charger and fuel cell into one unit (or car) if it 
helps. Then it would be electricity in and electricity out, 
like the other batteries mentioned.


> Hydrocarbon fuels not derived from petroleum may be 
> available in the
> future.

Certainly. And *producing* all such fuels will require 
storing energy into them, or using energy which is already 
there and which could be utilised in other ways if desired. 
eg much organic trash can be converted to hydrocabons 
suitable for fuel. But it can also be burnt directly to 
release energy, if desired.

>> Of course. Would you expect net energy out of eg a car
>> battery (lead acid . NimH/LiIon) ?

> No I wouldn't, but I think the battery would be better in 
> this respect than
> hydrogen.

There is no reason to think this must be so. It MAY be so in 
some implementations, but not in all implementations.

>> > Hydrogen's properties require you to spend more energy
>> > than you can
>> > earn,

>> Of course. It's an energy transpirt medium. For Alice to
>> argue this several times over makes it seem that she is
>> trying to con stupid people, or mislead ignorant people.

> Don't you think she is trying to make the point clear by 
> repeatedly stating
> this?

Yes. I do. And the point is misleading to the point of being 
invalid every time that she makes it. Yes, there are some 
sources of energy rich materials which can have there 
Hydrogen liberated for net energy gain. But they are largely 
in the same area as petroleum - finite resource. When you 
get to grown bio resources you are storing energy in them. 
If this is by eg using sunlight with eg algae the process 
may be low effort andf low pain etc - or may not. But it's 
still storing energy in the system from another energy 
source.

>> > because in order to get it you must overcome water's
>> > hydrogen-oxygen
>> > bond,

>> It's usually called "charging the battery".
>> ALL secondary batteries have this propery.

> Of course, but to what extent?

100%. In all cases.
Some chemistries may have a primary energy component due to 
using "partly charged" chemicals (to coin a concept) in 
their use, but after the first cycle it's all energy in >= 
energy out.


>> > and transport  hydrogen to the destination.

>> And? This is about a portable energy transportation 
>> medium.

> Even after petroleum has been transported somewhere the 
> net energy available
> is still positive, with hydrogen this isn't true and may 
> not be true for
> whatever fuel we use in the future. :(

ANY energy storage medium must by definition have a net 
energy deficit. All secondary batteries are prime examples. 
Petroleum ONLY works becvause we are not factoring in the 
energy used to "charge" it originally when the oil etc was 
made.


>> > It doesn't matter if all of these problems are
>> > solved, or how much money is spent. You will use more
>> > energy to create,
>> > store, and transport hydrogen than you will ever get 
>> > out
>> > of it."

>> There she goes again / still !!!!
>> It's a battery. A BATTERY.

> It's a very poor battery, if you want to call hydrogen 
> that. You lose energy
> to generate H2 (70% efficiency from electrolysis), 
> Liquefying the gas uses
> ~35% (65% efficiency) of the available energy.

No reason for electrolysis to be that low.
OTTOMH >90% is doable.

NOBODY is seriously suggesting using liquid Hydrogen for 
mobile end use. Great idea though !!! :-).
For mass transport maybe.
BUT even that can be improved if you are keen enough by eg 
coolth heat exchanging at the destination. Such an 
interesting spinoff is liable Too much for this sort of 
discussion ... .

> So if using a nuclear power
> plant that is 35% efficient

I don't think that % efficiency is usually applied to 
fission stations. Efficient relative to what? Total 
potential energy. Or ... ?

> ... to create the hydrogen then you're at a 16%
> efficiency. Yes, I think real batteries are better than 
> this, but the energy
> needed to produce the battery would need to be factored 
> in. The above
> percentages come from Friedemann's article, so if you 
> think they're off then
> I would like sources to better figures.

If one wanted some initial updates then wikipedia is often a 
good first start. Electrolysis would be a good firststarter.

> Hydrogen looks even worse when you factor in the 
> efficiency of the internal
> combustion engine that moves the vehicle.

Stirling engine?
Fuel cell?
... ?


        R

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist