Cheap Hydrogen? | Hacker News Reader

Cheap Hydrogen?

technologyreview.com

22 pointskelvin012 comments

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.

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.

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

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.

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

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.

H2 is a much smaller molecule than even methane, and containers designed to hold natural gas will tend to leak hydrogen.

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)

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

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.' :-)

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.

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

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