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urine powered generator from Africa; can it work chemically with something like struvite?

My organic chemistry knowledge is too slim and rusty to tell how or whether this urine powered generator from Africa might be able to be combined with aquaponics and/or struvite making, but I thought I'd start a thread here and see what people think. Seems like since the generator is running on hydrogen, the NPK etc. would still potentially be available as nutrient sources for plants if a system could be designed to combine the two ideas. What do people think?

http://thenextweb.com/shareables/2012/11/07/forget-apps-and-other-u...

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Permalink Reply by Kristopher Carter on November 12, 2012 at 12:14pm

The energy to electolyze the urea in urine into it's constituent elements has to come from somewhere. I'd like to know more about that. At first glance, it seems like the "brown gas" hype that people were using to magically increase their gas mileage. I don't want sound like I'm dissing the ingenuity of these young girls but I'd like to know more about this project before I buy into it.

Permalink Reply by Tom Cooley on November 15, 2012 at 4:59pm

I'd like to have more information about it as well...

Kristopher Carter said:

The energy to electolyze the urea in urine into it's constituent elements has to come from somewhere. I'd like to know more about that. At first glance, it seems like the "brown gas" hype that people were using to magically increase their gas mileage. I don't want sound like I'm dissing the ingenuity of these young girls but I'd like to know more about this project before I buy into it.

Permalink Reply by Vlad Jovanovic on November 15, 2012 at 5:56pm

I think you'd be hard pressed to get more energy out than you put in. If these girls have figured out away around that, they can look forward to long and illustrious careers in...well anywhere they damn well choose. Because I don't think anyone has ever done that yet.

You can crack regular 'ol water for the hydrogen, but thus far the energy (usually electrical or thermal) it takes to do that is more valuable/useful (in terms of energy) than the hydrogen is. That has been the 'catch' thus far. Though their is a real interesting new comer to the myriad of electrolysis/water splitting technologies...photo-biological water splitting. Using an algae reactor. It appears that when algae are deprived of sulfur, they switch from photosynthetic production of oxygen, to hydrogen production. At the moment this method at least appears economically feasible. Pretty cool stuff.

The article linked never mentioned the kW rating of the generator, nor what it was that you could "run for 6 hours"...an LED diode? Or a household?

Permalink Reply by Tom Cooley on November 19, 2012 at 6:32pm

Thanks for the feedback, Vlad. It'll be interesting to see (if we do) whether this was more of a science fair project or a marketable invention.

Permalink Reply by Eric Warwick on November 21, 2012 at 7:15pm

I looked at the article and all it really stated was a chemical reaction. If the reaction is exothermic (meaning the chemicals lose energy at the end of reacting) rather than endothermic (gaining energy from the surroundings), then it's an energy source. If not, it's just a way to store energy more efficiently. From the article: "Urine is put into an electrolytic cell, which cracks the urea into nitrogen, water, and hydrogen." This requires energy because of the chemistry behind it. N2 and H2 are the elemental states of Hydrogen and Nitrogen. Barring a large proof that I am at a loss to provide (especially in plain English), it should just be noted that this means it is endothermic.

The invention is still good engineering, because it can provide energy security in the form of storage. It's not actually a generator, though. That's all. I think I'll ask my AP Chemistry Teacher for a proof (for my sake at least) before discussing more. Anyways, thanks for the article, it was cool.

Permalink Reply by Vlad Jovanovic on December 5, 2012 at 3:20am

Well the generator is a generator Eric...Just a 'run of the mill' electrical aggregate generator that's been modified to run on hydrogen gas...Instead of gasoline, or deisel fuel... (similar to how you can modify one to run on propane, natural gas, etc...currently I'm sorta working on one that will run off of wood gas, from wood chips. Again, this is nothing new...when I say "working on" I don't mean anything ground breaking, just a better (while still being cheap) way for me to filter the gas so it doesn't gum up the electrical aggregate generator after a while, is all. The Imbert wood gassifier's been around since WWII, I think they just ran the gas through a box of moist wood shavings, which is probably fine if your using wood to run an old truck or car...maybe if I can find an old Russian army generator from the 60's or 70's, instead of using one of these new ones...probably nowhere near as finicky/sensitive).

At any rate sorry for rambling...Let us know if your Chem teacher comes to a different conclusion other than, hydrogen cracking/electrolosis (and all the transfer losses that come with it) uses more energy than the hydrogen is worth. (I don't mean "worth" in terms of money, but "worth" in terms of energy...to turn a shaft, run a generator, power a factory etc)...

Eric Warwick said:

The invention is still good engineering, because it can provide energy security in the form of storage. It's not actually a generator, though.