# Methane Production



## countryboy84 (Dec 8, 2010)

Hey guys I have been reading a lot about using your animale waste to produce methane. I understand how and why it works and really like the idea. I have read in one place that using inner tubes to store the gas could be dangerus due to static build up. On the other hand inner tubes are the number 1 way of collecting the gas and has been used for years. does anyone have any experiance with this.


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## Windy in Kansas (Jun 16, 2002)

No experience but I did read up on the subject many years ago. What I learned was that the gas if very corrosive unless streamed through something like lots of iron filings such as from a lathe output, milling machine, etc. 

I don't know how you plan to use the gas but you may want to research that aspect of it if you weren't already aware of it.


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## fishhead (Jul 19, 2006)

If static electricity is an issue couldn't you just ground the tubes?

I've been wondering if a person couldn't use the round bale tubes for the chamber. Just fill them up with the right ratio of C:N and water and let it cook.


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## Windy in Kansas (Jun 16, 2002)

fishhead said:


> If static electricity is an issue couldn't you just ground the tubes?
> 
> I've been wondering if a person couldn't use the round bale tubes for the chamber. Just fill them up with the right ratio of C:N and water and let it cook.


I'd question if the weight of the bag would be enough to force gas from it? With an inner tube the gas is under pressure as it builds and is forced back out via that very pressure. 

Some systems use a shell housing over another which the gas lifts about the other as gas is produced. The weight of the shell forces the gas out of the unit. Kind of like pushing down on a block of styrofoam floating on water.


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## Harry Chickpea (Dec 19, 2008)

The chances of air getting in the inner tubes is extremely small if you keep even a small amount of pressure in the system. A gasholder is a much better idea. It can be as simple as a 50 gal drum filled with water, and a plastic drum liner with the bottom cut out placed into it.

The bigger issue will be keeping the waste warm and at the proper pH balance. Reaction slows down tremendously when the stuff is cool. Also, don't expect a usable amount of gas unless you have a lot of animals.


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## fishhead (Jul 19, 2006)

I saw a video of Jean Pain where he made his wood chip pile for heating his house and water. Inside the pile he put a small container of methane producing material. That kept the container warm. The gas went into a manifold of a bunch of truck tires. When the tires started getting full he would run it through a compressor and put it in a portable tank to run his little pickup.

http://www.electricitybook.com/composting-for-heat/


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## ryanthomas (Dec 10, 2009)

fishhead said:


> I've been wondering if a person couldn't use the round bale tubes for the chamber. Just fill them up with the right ratio of C:N and water and let it cook.


I like that idea. I've seen them in third world countries made out of 3-4 foot diameter poly lay-flat tubing, but I haven't been able to find any that size here. Never thought of the bale wrap tubing. Seems like it would work.

The Jean Pain method of using vegetative material instead of manure does produce more methane. Some people (not me) think he was a fraud, though, that he greatly exaggerated his results. The information available about his specific set-up is pretty limited and I haven't been able to find anyone yet who has matched his methane output from such a small volume of feedstock.

I've only done very small experiments so far, but I'd like to make a very cheap large batch digester just for warm weather experimentation. Thanks for the bale tube idea. I'll have to look into that.


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## fishhead (Jul 19, 2006)

Ryan,

You might be able to get some free used bale tubing from a farmer. They can only use so much old tubing before it becomes a waste to get rid of.

I've dug into sawdust piles that were at least 20 years old that were still too hot to dig into with bare hands. They must get their nitrogen from rainwater. That might be why they produce heat for so long.

Combine a large sawdust pile with a well insulated house and it shouldn't cost more than $50/yr to heat a modest sized house even in MN where we had -22 yesterday morning.

I was surprised that wood chips would only heat for 18 months after seeing sawdust piles do it for decades.


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## speedfunk (Dec 7, 2005)

http://onestraw.wordpress.com/2010/11/04/midden-leau-chaude-the-big-build/

hes doing some cool stuff similar to Jean Pain... check it out


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## fishhead (Jul 19, 2006)

Thanks. It will be interesting to see how much heat it generates and for how long.

I'll bet there are some grants to cover the cost of monitoring and recording instruments.


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## ryanthomas (Dec 10, 2009)

In answer to the original question, I talked to a dairy farmer I know who has a large methane digester. He doesn't use inner tubes, but they use plastic pipes to get it from the digester to the generator and he said static electricity has never been a concern for them. It can also build up in plastic pipes, but shouldn't be a problem unless something metal punctures the inner tube to ground it, AND there's air in it at the same time. Like Harry said, a little pressure inside should keep all air out of the system. On a small set-up I wouldn't worry about it. But if you really want to be extra safe maybe you could somehow permanently ground the inside of the inner tubes.


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## countryboy84 (Dec 8, 2010)

I am only going to be cooking and heating water with the methane. The water heater is a on demand natural gas system that does not have a pilot light so it is very easy on the gas usage. I plan to build 4 of these digesters. From what I have read if kept at proper heat and ph then once they start producing they will keep going for about 6 weeks. I can get all the dung needed from a dairy just a couple of miles away. would take less then a picup load every 6 weeks to fill all 4. I had planed to keep positive pressure on the system once I start collecting the methan for use. I read that a 55 gallon drum setup like I am planing will produce about 80 liters a day for the frist to weeks then drop of some before picking up a little right before it stop producing. at that rate I should get about 320 liters a day. I mean that is if I was reading a good source of information which I think that I was. If I had a scanner I would put the plans up here for you guys to look at. And to address the corrosion problem I have a scrubber setup to clean the methane up.


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## ryanthomas (Dec 10, 2009)

That sounds like a good plan. Please let us know what kind of results you get from that. There are a lot of variables, so it may be more or less than what anyone else has gotten. You might also want to consider throwing vegetative waste in with the manure. Anything with sugar or starch will increase your methane output.


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## mossywyatt (Mar 24, 2009)

Why 4 smaller one's and not one bigger one? I would like to see a set of plans. Methane collection seams like a no brainer. wyatt


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## countryboy84 (Dec 8, 2010)

I am doing 4 smaller ones because I can pressurize the gas in the inner tubes some what this way with out a compressor. When the small barrel rise and I have to push it back down to get the methane out and in to the tube. I have filled tractor tubes to 60lbs of air so I know they will take the pressure since I wiegh about 160 I should be able to get the 60 psi in there. My only wonder is about how many cft will there be in that tube when it is at 60 psi. Can't wait till winter is over and I set this up. And if everything works I will be making sure that I fix up a wau to keep the temps of the digesters up next winter too.


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## fishhead (Jul 19, 2006)

Did you have 60 psi in the tube with it unrestrained in a tire?


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## countryboy84 (Dec 8, 2010)

yeah we use them as sleds here in the winter when the snow is deep enough lotta fun. With it not in a tire is really gets to be big and fat at 60 psi but it holds it well and can take to running full speed and jumping on it to go over a hill so I am thinking at just laying there at 60 psi I should be fine.


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## Harry Chickpea (Dec 19, 2008)

countryboy84 said:


> I am doing 4 smaller ones because I can pressurize the gas in the inner tubes some what this way with out a compressor. When the small barrel rise and I have to push it back down to get the methane out and in to the tube. I have filled tractor tubes to 60lbs of air so I know they will take the pressure since I wiegh about 160 I should be able to get the 60 psi in there. My only wonder is about how many cft will there be in that tube when it is at 60 psi. Can't wait till winter is over and I set this up. And if everything works I will be making sure that I fix up a wau to keep the temps of the digesters up next winter too.


Huh? PSI = Pounds per square inch. When you push down with 160lbs on something a foot square, you exert a pressure a little over ONE pound per square inch.

If you are batch processing, the idea of using four units works better if you stagger the loading every couple of weeks. That way, overall flow remains fairly constant. 80 liters of gas per day is optimistic.


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## countryboy84 (Dec 8, 2010)

with the PSI you have to look at the digester as a hand bike pump, not as a flat block taking wieght. When you push down on a bike pump you can put a lot of psi in a tire. but not equal to body weight lest I can't had a heck of a time tring it when I had a flat on my ton truck trying to get 80 psi in there I use standing on the pump with both feet and could not get it to push any more. but I use younger then to and had a cheap pump. But I am will test this again with just air coming out of the barrel and water as my pushing media to see if I am right.


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## ryanthomas (Dec 10, 2009)

I don't quite understand how you're planning to get 60 PSI from just pushing on it either. Unless I'm missing something, if you put all your weight on the drum you'll get something around half a PSI. Also, at 60 PSI make sure you use a regulator before the appliances that use the gas. Standard for natural gas appliances I think is less than a quarter PSI. It's measured in inches of water column, which is a much smaller unit than PSI.


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