The Walden Effect: Farming, simple living, permaculture, and invention.

Home made hydrogen power

  hyrogen powered chicken coop door opener

A perfect complement to yesterday's solar powered automatic chicken coop opener would be this portable hyrdogen generator.

Kristie Lu Stout has an interesting post about this exciting new product that will allow everybody to generate their own hydrogen from water and store it in a safe, low pressure battery-like container. No word yet on how much it might cost, but plans are to have a tabletop model available by the end of 2010.

Getting off the grid with solar or wind has always come back to battery storage. If this technology improves, it could replace most of those expensive and toxic chemical batteries and bring alternative energy within the reach of the common homesteader.

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

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While hydrogen is a clean energy carrier, it does have its problems.

  • Really low density be it gaseous or liquid. This means that you'll need very big tanks. (check out the externel fuel tank on the space shuttle. The cone on top contains liquid oxygen, the rest is liquid hydrogen)
  • Really hard to store. Hydrogen will leak slowly through pretty much any container because its molecules are so small. That's why attempts to create composite hydrogen tanks for spacecraft have failed, at least until now. It also embrittles many metals.

So to get a reasonable amount of energy stored, you need to put it under really high pressure, or cryogenically cool a high volume of the stuff. Both are hard/dangerous. A hydrogen fire is extremely hot but does not give off much visible light. It also takes very little energy to ignite a hydrogen/air mixture, about 1/10th of the energy that it takes to ignite a gasoline/air mixture.

So as energy storage, alcohols like ethanol are much safer, because they are liquid are room temperature and pressure.

Comment by Roland_Smith Tue Feb 9 02:29:16 2010
Hmm --- maybe they dealt with some of the problems, which could be why people are excited by it? We'll have to wait and see if it's a real wave of the future or just another gimmick. :-)
Comment by anna Tue Feb 9 08:03:34 2010

Hmm, it looks like they're storing the hydrogen by bonding it to a metal, in the form of a metal hydride. According to the manufacturers documentation, the energy density of these storage capsule is about the same as that of a good Li-ion battery (160 Wh/kg). Given that you'd have to feed the hydrogen to e.g. a PEM fuel cell with an efficiency of 40-60%, practical energy density is about half of that of a battery.

If you look at the manufacturers website, these canisters are for an open toy RC car. Now, for metal hydrides to give off hydrogen, you have to heat them. Usually this is done with waste heat from the fuel-cell. Given that hydrogen leaks easily, and there is a hot fuel cell generating electricity nearby, I'd be cautious about putting a scaled-up version of such a device in an enclosed space. You'd have all the ingredients for "goes boom" in one convenient package. :-)

There are already fuel cells commercially available that can directly use e.g. methanol. If a carbon-neutral and efficient way could be found to generate methanol (or syngas, because that is easily converted into methanol), that sounds like a safer option. See the methanol economy article. Methanol is harder to ignite than gasoline, easy to store, and has an energy density an order of magnitude greater than highly compressen hydrogen and 15 times higher than a Li-ion bettery.

Comment by Roland_Smith Tue Feb 9 14:01:49 2010
Methanol sounds intriguing --- I'd never even heard mention of it. Maybe if we're lucky one of these options will come together before too long! The toxicity of batteries does make me concerned about the sustainability of our golf cart as an on-farm travel option...
Comment by anna Tue Feb 9 15:25:29 2010

Well, pretty much every kind of rechargable battery available today uses toxic and/or highly reactive components. At least lead/acid batteries can be and are recycled pretty effectively.

Maybe ultracapacitors will one day be able to replace batteries, not not for a while. With the current trend towards electric cars, there is a lot of work being done on storing electric energy. Something useful will pop up sooner or later.

Comment by Roland_Smith Tue Feb 9 15:56:06 2010
Yeah, I figure it's just a waiting game. If I can be patient (not one of my virtues), something ecologically friendly will pop up eventually!
Comment by anna Tue Feb 9 18:29:22 2010
The points like hoe hydrogen molecules react and a overall bonding gets formed, are good. I like the blog.
Comment by Anushka Tue Jun 1 02:05:51 2010
Thanks! :-)
Comment by anna Tue Jun 1 08:01:20 2010

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