

Cheap Hydrogen? - kelvin0
http://www.technologyreview.com/news/428260/a-better-way-to-get-hydrogen-from-water/?mod=related

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nsxwolf
Water is the ash of hydrogen combustion. The energy has already been released.
These news stories keep telling a fairytale - that we're getting closer to
some technology that will effectively convert water into gasoline.

Hydrogen from water is a potentially useful energy storage medium, but it's
not a free energy source.

~~~
ColinWright
Correct, but it appears that this process requires (lots of) heat, and that
can be obtained from solar furnaces. If this works then we can use a solar
furnace and directly create hydrogen gas, missing out all the efficiency-
sapping intermediate stages and going straight to a storable fuel.

~~~
tambourine_man
The problem is that H2 is very volatile, so storing it efficiently is not
trivial.

~~~
roc
Nor is transporting. Both of which explaining why hydrogen fuel cell
technology is now feasible for mid-range electrical generation (Bloom Box),
but still generally DOA for vehicles.

That is: generation cost hasn't been _the problem_ for a while. It's all about
storage and transport. And marginally cheaper h2 generation isn't going to
make hydrogen make more sense than electrical batteries.

Though I am curious to see how well a setup of this technology driving H2
separation and feeding a fuel cell stacks up against a more traditional steam
turbine.

~~~
Shivetya
transport is the same as natural gas and that is already in place.

~~~
ken
Hydrogen has a number of unique safety issues:
<http://en.wikipedia.org/wiki/Hydrogen_safety>

Unlike most gasses, hydrogen gas flowing through leak warms up, and the low
ignition energy means this can be enough to start a fire, and hydrogen flames
are invisible.

I'm not a chemical engineer, but I would assume that methane infrastructure
cannot simple be re-used for hydrogen without significant changes.

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ChuckMcM
Sigh, this compares unfavorably to using titanium dioxide as a photo catalyst
with ultraviolet light. In the TiO2 case the source material is cheap, the
temperatures are not especially elevated, and the energy source (the Sun) has
solid energy output in the UV bands.

I read stories like this and put them on the shelf for times when I see a
system that happens to have a lot of excess heat and is looking for a way to
put that to use. (besides steam turbines)

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kelvin0
Dan Nocera (MIT) project seems quite interesting and seems to require much
less energy by using something different than direct electrolysis:

<http://www.youtube.com/watch?v=KTtmU2lD97o> And 'his' company:
<http://www.suncatalytix.com/about.html>

~~~
ChuckMcM
Yes, it is definitely more interesting than the OP's project :-) but also not
in any form of production yet.

I believe it was the presentation Dr. Nocera did for the DoE was a pretty good
treatise on the assertion 'if you can't do it as well as plants you are doing
it wrong.' :-)

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maeon3
Could the hydrogens be assembled into the carbon and hydrogen chains that make
up gasoline? Specifically isooctane and butane? If so, a solar thermal to
gasoline converter like that would make you an instant billionaire.

~~~
Symmetry
Well, not by itself but from the little reading up on gasification I did just
now it seems that a cheapish source of hydrogen might make turning coal into
gasoline much more economical. <http://en.wikipedia.org/wiki/Fischer-
Tropsch_process>

