Funny NYPD

if hydrogen is available, Ford and BMW will make you a hydrogen powered vehicle.

__________________
Funny N., Au Group Electronics, USA, www.AuElectronics.com

crashsite

The problem with the "what if game" is that you can come up with any scenarios you want. But, what if the wind does blow and if the clouds do clear and what if a nuclear bomb goes off just close enough to your home that you get the heat energy without the radiation...and so on (ad infinitum).

For the most part, sun shines, wind blows and waves crash...and the tides come in and go out and water falls from the sky and rushes to the sea and the magma under the earth will still be hot long after humans have run their course here on Earth. The question is: Will we do both the easy giant and not so easy baby steps to try to extract as much of that energy as we can with the minimum impact on the Earth or will we throw up our hands in frustration that baby steps are hard and just continue drilling for oil and digging for coal and cutting down forests and collecting cow farts for fossil/bio-fuel energy sources?

I know this isn't exactly the technical discussion of the topic but, I beleive it is the precursor to the technical thinking that will be needed to make the tough energy sources viable.

wmmullaney

What are the chances of a nuclear bomb blowing up somewhere near my house? About 1 to 100,000,000. And the wind 1 to 4. The sun does shine most of the time, but when it doesn't????

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crashsite

When they don't...they don't. You design the system to take as full advantage of what's the most available. For example, building a solar plant in a cave just because the land is cheap is no bargain. If a system has a net positive output (over time) and if you build a LOT of them, I think you could reap appreciable power. The power is there and 99.999999 is passing by with no attempt to utilize it beyond what nature uses it for. I think it's more a mode of thinking than a "real" problem that more aggressive measures are not being taken.

Regarding the chances of a "harmless" nuclear explosion near your home. Well, the odds are still better than Jessica Simpson having an intelligent thought (so, how come she has more money than I do?...........Oh, yeah, those).

wmmullaney

How much hydrogen can you get from a solar powered splitter?

Or just for a test, a 9v battery?

__________________
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William Mullaney

"HOPE for the best, EXPECT the worst, ACCEPT whatever comes."

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Nigel Goodwin

Generating hydrogen is just a way of storing the solar energy, and not a very efficient one, the actual amount obviously depends on the output power from the solar panel - but you would be talking massive panels, in very sunny parts of the world, to get a useable amount.

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jpanhalt

First, you need to decide whether you want the answer as determined by conventional chemistry or by methods used by those who believe in over-unity production, mystical properties of "brown gas," etc.

The following calculation is based on conventional chemistry. For more detail, see these links (among hundreds):

http://www.science.uwaterloo.ca/~cch.../nernsteq.html
http://www.nmsea.org/Curriculum/7_12...ectrolysis.htm

For those who are not too picky and don't want to get wound up in what are basically unit conversions, consider the following equations:

H2O = H2 + ½O2 Eo = 1.229 V ; and
2H+ +2e- = H2


To get one molecule of hydrogen, H2, from 2H+ you have to provide 2 electrons.

A mole of hydrogen occupies 22.4 L at STP (approximately 29.92 inches of Hg at 32° F ) and contains 6.02X10E23 molecules. Thus, a mole of H2 requires 12.04X10E23 electrons to produce.

Doing the math, production of 1L of hydrogen requires 5.4X10E22 electrons or approximately 8,700 coulombs.

Assume your 9V battery is rated for 500 mAH ( I am too lazy to look up a real value). An hour is 3600 seconds. A current of 0.5 A for 3600 seconds is 1800 coulombs.

Thus, your 1800-coulomb-capacity battery will produce a maximum of 200 mL of hydrogen gas at STP. Efficiency is probably a lot less than 100%, so individual results may vary.

If you are more comfortable with electrical nomenclature, the Faraday is 96,489 coulombs per mole. Since production of H2 reuires 2e per mole of gas, then 192,978 coulombs are required per mole of gas. At STP, a mole is 22.4 L (same as above), so a liter will require 8600 coulombs. The difference is due to rounding.

The simple answer: A 9-V non-rechargeable battery is an expensive way to produce just a little hydrogen.

John

edit: better defined which battery type

crashsite

That's a very impressive disertation, John. Working down through your numbers I get the imopression that it's not that it's not "do-able" it's whether it's practically do-able. Of course nobody says it's easy or it would already commonly be done. The big problem is that you can't bypass the physics of the conversion and thus must concentrate on the process itself (by improving the efficiency and by massive parallel processing with a companion collecting network), In that context, can it ever be practical? I don't know but, THAT was the question I asked in my original post on this topic.

The numbers you cite suggest that it's sort of on the edge of practicality but, at the present state of the art, probably still on the "not practical" side.

Oznog

Yeah those pesky physics keep presenting nothing but problems...

Practical for what?? Running an internal combustion engine, no. A fuel cell, IF you could find a decent way to store many pounds of hydrogen and have a cheap, plentiful source of electricity or some exotic way of generating H2 like algae, sure it could be practical.

Electrolysis becomes electrically more efficient at high temps, where it absorbs some of the heat energy cooling the solution down so it requires more high-temperature heat and high temp heat isn't often free. There's certainly a lot on making better electrolytic cells. They usually use a very alkaline solution too. But, its electrical power requirements are still quite high.

__________________
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crashsite

There is another factor besides the physics and "mechanics" of it all. While I realize it's very politically incorrect to say, there is a satisfaction component of slapping the Arabs and Venezuelans (did I mangle the spelling on that or what?) in the face and telling them where they can put their oil. It's certainly not uncommon for people to spend a lot extra for spite (a lot of expensive windshield replacements are due to baseball bats and girl/boy friend tiffs). Maybe it's time we (Americans and others) get a bit upity about it and make a bigger alternative energy push. We may even get a pleasant surprise (like some companies that have been forced to put scrubbers on their smokestacks and discovered that they had a "gold mine" of recovered materials).

Well, I suppose this topic has pretty much been beat to death, eh?

desiturtle

!
I've seen it spread on ground here in N Ireland, complete with condoms and sanitary waste. I believe it is regularly spread as fertiliser here!

jpanhalt

The main problem with using relatively untreated human waste as fertilizer is infectious diseases. Appropriate food preparation helps, but doesn't entirely eliminate the risk. Viruses, parasites, and bacteria are the main etiologic agents of concern. We had a major outbreak of hepatitis from green onions at a popular Mexican restaurant a few years ago. They were imported from an area that used human waste as fertilizer. Parasites (e.g., cryptosporidium, etc.) can also be a problem if the food is under cooked or not properly cleaned. And of course, you have probably heard of cholera, E. coli O157; H7, typhoid fever, and others.

One species’ pathogens are often less infectious for other species than for its own species. What you don't want to do is create a cycle of infection in the same species. It is better to use cow dung for human food crops unless there is good control of the processing of the human waste. However, the purveyors of s__t may not pay much attention to regulations.

In spacecraft, there is much better control of the environment, the occupants, vaccinations, sanitation protocols, etc. John

crashsite

Having seen the TV show lineup for this season, I'd have to conclude that you are right.