crashsite

A common science experiment is to crack water back into elemental hydrogen and oxygen and, it's pretty easy to do. Of course, the problem is that it takes more energy to separate it than you get back when you re-combine the hydrogen and oxygen back to water again.

But, if you can find a "free" energy source (the sun) that's otherwise just going to waste, can it be practical to do the cracking at home?

Communist China tried the concept with poor success by having families set up small smelters to generate steel for industry. Unfortunately, the quality control was spotty and the steel output sub-standard. Hopefully, technology has advanced some since then.

Lets say that a photovoltaic solar array is used to provide the electrical power and appropriate electronic and electrical devices are used to control and monitor the process. By having the cracking be automatically taking place whenever there's sufficient sunlight, the home setup would generate the hydrogen and drive it into a relatively low-pressure tank (similar to a household type propane tank).

As the tank would approach capacity, it would report its status to the "hydrogen company" (probably a public utility like the electric, gas, water and phone company) that would have a collection truck stop, on its route, and extract the hydrogen while measuring the volume taken. The family that generated the hydrogen would be credited similar to the way a family can now generate electricity and drive it back into the electrical grid for credit. When the family hydrogen fueled car filled up, the credit would automatically be applied.

What I don't know (and hope people out there in cyberspace do) is whether sufficient hydrogen could be produced and harvested in this manner to make it worth the effort. Unlike LPG, the hydrogen would stay gaseous and would not be as efficient as propane, for the same size tank but, with millions of units operating most every day, would it be efficient enough to be practical?

Also, since propane is a hyrocarbon fuel (and I've read that the most common and efficient way to get hydrogen now is to extract it from natural gas), I wonder if the hydrogen could simply be driven into a propane tank to make a hydrogen enriched propane that would be used (by families that use propane) directly? I'm no chemitst and don't know the ramifications of all this.

RLJ

BIOGAS (Methane) would probably be the most efficient. Most small farms would have cows, pigs or other other livestock which would generate waste (human as well but most human waste is too rich and must be 'watered' down). A small biomass converter would be easy to setup and maintain. The gas concentrator (holding tank) could then be off loaded and the gas scrubbed and prepared for further compression. Another feature would be that a small portion of the collected gas could then be drawn off for the cooking, heating or power production using a generator modified for burning methane for the farm.

As with anything there would need to be some training and safety precautions but this would be easier and produce more methane gas in less time than hydrogen as well as being able to use 3rd world material. Back in the mid 70's Mother Earth News carried a 55 gal drum gas production unit which used a 55gal drum, a tractor innertube and propane gas stove.

Just a thought.....RLJ

Pommie

This may be of interest, it's an article from 1991 about home (farm) Methane production.

Mike.

ericgibbs

Interesting article.
At the moment we trade our pig/goat and other slurry with local nursery gardens, just wonder what change in soil enrichment terms occurs after/during digestion to get the methane?

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Pommie

Eric,

You read VERY fast. I have a few more Home Power articles archived on a disk. They don't appear to have any copyright notice on them. Anyone know the legality of posting some here?

Mike.

RLJ

Everything I have ever read talks about the slurry left after methane productions can be used for soil enrichment. Although in the back of my head I remember something about if human waste was used that there 'might' be some issues with health departments. The product that comes out is really a 'composted' product and any harmful biological bacterial have been either killed off by the lack of habitable atmosphere, heat generated or the lack of 'digestive' material. The decomposition and release of the methane gasses (byproduct of digestion...yep, igniting release of gasses from the bodies orifices) is the active process.

The rule, if I remember right, when the production of gas is stopped the digestible material is used up and the environment has killed off all bacteria (good and bad) and the material which is left can be used for soil enrichment.

Again, fuel source for the farm, easy setup using cheap material, soil enhancement and commercial production of gas...seem like a win win situation
to me.

RLJ

Also, this article recaps what I remember from the old Mother Earth News...even similar designs.

Nigel Goodwin

As I understand it, certainly in the UK, you're not allowed to use human waste as fertiliser - although I don't see as there's any more biological risk than anything else?.

In a closed environment (such as a long distance space craft) you obviously would have to recycle the human waste products.

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ericgibbs

hi Mike , RLJ,
There is no human waste in the mix, the human waste goes into the French drain that we built about 6 years ago, that drain works just fine.

Im due to fly out to our farm in South Africa in a couple of weeks for two months, I'll discuss the methane idea with my son.

He always has some project or other lined up for me.

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RLJ

U.S.(states) is the same way, from what I recall. From what I have read animal waste and vegetable matter used as material from methane production is more efficient. It does not have to be 'cut' as much and it processes faster through the digester so you can keep 'feeding' it.

RLJ

RLJ

Check the internet before you head out. While the technology is simple I know that there are some things you can do like keep the temp in a certain range and work with the ph if you decide to try this.

If nothing else it could be something to 'tinker' with...but remember all the safety precautions....things that burn can prove hazardous, especially if under a little pressure. I have memories of exploding glass test tubes from my High School chemistry class of an experiment with a plugged vent tube to prove that!

RLJ

wmmullaney

This is kind of off-subject from crashsite's post. Can someone give him an answer?

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jpanhalt

Hydrogen burns at a much higher temperature than propane burns. Hydrogen flames are typically invisible, unless impurities are present, and hydrogen flames are difficult to extinguish, i.e., they are almost impossible to blow out. I don't know how the mixture with propane would behave, but my experience using hydrogen torches is that they have definite uses, one of which is not in the home for cooking. If one produces a surplus of hydrogen, I would suggest just transporting it to a place for proper use, as in fuel cells.

As for methane (natural gas), it is easy to transport as the compressed gas or refrigerated liquid. Moreover, it has the property of forming clathrates with water (effectively forming an ice with a high concentration of methane and much higher boiling point than LNG) that may make it an even more attractive as a easily transported fuel.


John

mneary

Why do so many people think that hydrogen solves any problems?

If you have excess electricity, it is much more efficient to sell it to your utility using the infrastructure that's already in place. In many areas, PV produces maximum power just when it's wanted: to run air conditioning!

It's really inefficient and dangerous to make H2 and collect it by truck.

jpanhalt

While I agree with the efficiency statement in the context of the discussion, I am not aware of any data showing that hydrogen is more dangerous to transport by truck than other substances, such as water, fertilizer, and fuel oil. I am not referring to the labeling requirements, but rather to actual data with respect to accidents and injuries.

John

mneary

It's the transfer of the hydrogen that concerns me, not the highway safety.

I have no data.