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Comment by stcredzero | Hacker News Reader

> I also see no mention of why using urine is better/worse than just using regular water. I am guessing because "Putting electricity in water generates hydrogen" is a less exciting title.

This is not electrolysis of water. In theory, they are decomposing urea to get their hydrogen, which uses far less energy. This is the same principle that would cause a hydrogen economy to be run off of natural gas. Sometimes a little knowledge is a dangerous thing. Or, in the words from Spinal Tap, there's often a thin line...

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There isn't all that much urea in human urine - less than 3%.

I point this out in another comment, but that's a good point I hadn't taken into account. Getting hydrogen from urea is better than electrolysis, but there's not that much urea. Still, if the entire village contributed, it might be enough to charge cell phones and run LED reading lights, which would still be a huge boon.

You still have to input energy to get hydrogen from urea, so why not just use that energy directly?

The only good reason to extract hydrogen is for storage. For example, solar energy could be used to extract the hydrogen from urea, which could then be burned at night to continue to generate power.

On it's own, any technology that requires extraction of hydrogen will result in a net loss. Sometimes a HUGE net loss.

> You still have to input energy to get hydrogen from urea, so why not just use that energy directly?

If you can do it efficiently enough, in theory electrolyzing urea then burning it to water (and nitrogen) is a net gain in energy.

I believe you are mistaken in this case. The technical paper, linked from the article, will explain better then I can: http://www.suttonfruit.com/pics/urea_electrolysis.pdf

> Still, if the entire village contributed, it might be enough to charge cell phones and run LED reading lights, which would still be a huge boon.

If you think people in undeveloped countries need to generate power from their urine to charge their cell phones, you really need to get out and see the world.

Granted, I really do need to get out and see the world. But I had thought that 'burner' cell phones were quite ubiquitous in the developing world?

Sure they are. Anywhere in the developing world that has power to run a cell tower clearly doesn't need to be extracting power from urine.

I would assume running wires to a few cell towers considerably cheaper than running wires to many villages. Indeed, isn't that why cell phones themselves are much more common than landlines in rural Africa?

No, it's because many developing countries "skipped" a technology. They missed out on land-lines because they were undeveloped, and now they have electricity and infrastructure, they jump straight to cell phones.

For this reason, countries like Ecuador, Guatemala, etc. Have cell phone rates higher than developed countries like Australia and the US. http://en.wikipedia.org/wiki/List_of_countries_by_number_of_...

Jeesh, it's like you're missing the trees for the forest here. Skipping technologies is the pattern but there's a reason for pattern.

Developing countries don't skip technologies out of a desire for hopscotch or something. They skip wired tech because copper wires are expensive, their expense doesn't go down over time in contrast with the increasing sophistication of chips. Conventional phone lines and electrical power are both wired tech. Thus both are harder in third world conditions.

Not all villages in developing countries are dirt-poor and desperate for the slightest technology. Cheap cell phones are used quite a bit in many rural areas in Africa, for example: http://www.cnn.com/2012/09/13/world/africa/mobile-phones-cha.... For example, farmers can use them to look up weather forecasts and price information for their crops.

Yep, that's exactly what I was saying.

I think the point is that villagers from those rural areas can generate power the old-fashioned way, by burning fossil fuels.

Or biofuel, http://biolitestove.com/homestove/overview/

Relevant> http://gadgetwise.blogs.nytimes.com/2012/11/06/biolite-stove...

That doesn't help. If you electrolyze water with 3% urea the vast majority of your energy is used to split water, and only a small portion of it will split the urea.

But electrolyzing water, and then burning hydrogen is a net loss in energy, and the 3% urea does not give enough advantage to offset this.

Maybe if you had some way to preferably electrolyze just the urea and leave the water alone, but then you have to deal with batch process (instead of just continually adding liquid), and the lower voltage makes the reaction too slow.

The technical paper linked from the article[0] explains how this is done. The electrolysis of urea does compete with the electrolysis of water, but it happens at a lower voltage.

[0] http://www.suttonfruit.com/pics/urea_electrolysis.pdf

edit: grammer

There's probably more value in the urine as fertilizer.

Is this a common practice in Africa? If it's not, then a village already meeting its fertilizer needs can have power after dark in addition.

Depends on the salt (Na) content.

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