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methane--another way to handle it

 
Joshua Myrvaagnes
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Building a biogas digester was our exciting idea for reducing our (possible) methane production from our compost piles here in an urban yard, but it wasn't practical for our situation.  I say "possible methane" because I don't really know how much our compost piles may be producing, and how exactly to tell the smell of methane from nitrogen, but i've read that even a little methane has a significantly higher greenhouse gas effect than carbon dioxide (like 6 times or maybe far more than that, I recall seeing very different figures).

I just read an article in New Scientist about growing animal feed pellets with bacteria from methane/natural gas, and while I don't think that application is a positive, the bacteria -- methanotrophs -- could do a lot of good in application in a compost pile, turning methane into animal feed (theoretically) or simply into more food to compost.  (Building a biogas digester would have been impractical for us, required too much babysitting, and not produced enough fuel to cook breakfast moore than once in a week or something.)

Thoughts?

Other applications?

And how do you know when you've got methanotrophs naturally occurring in your soil or compost?
 
Joshua Myrvaagnes
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In the first two decades after its release, methane is 84 times more potent than carbon dioxide. "  --edf.org

this source says methane is 84 times more potent a greenhouse gas than CO2.  Hm...also that it accounts for %25 of the greenhouse effect currently.

This seems like low-hanging fruit, people!  methane can be burned with a match! CO2 can't. 



also from another source--naturally occurring methane sinks in the woods, methanotrophs thrive when trees are present to keep hte water table below the soil surface.  Human impact can affect this, although there have always been swamps and stink I suppose.  More biomass underground, more roots, more living plants seems to help.

On an unrelated but happy note, my engineer housemate's coworkers, who he's described as gun-toting jerks in the past, apparently also are very into growing food plants, keeping chickens and bees, and generally being self-reliant.  Now that I've derailed my own topic, back to compost.

Oh, methane itself is apparently odorless from the first source that comes up, but the accompanying things (sulfur, ammonia) are probably good indicators that it's there.  Surest way to tell is light a match (but be careful!)
 
Travis Johnson
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I am still researching biogas as a potential use for us.

We are a bit different in that we are very rural and have a commercial sheep farm, but you are indeed correct in that the gas output is not very high. It really shouldn't be, our sheep have already extracted half of the biogas out of it themselves. I have done some preliminary research and it seems we should be able to produce about 40 lbs of biogas per month, which is twice what we currently use to cook with, but that is pure propane and not biogas. Currently that stove is not tied in with my big 500 gallon propane tank, so it only makes sense to tie it into a biogas system and see if we can cook our food for free.

It should be an interesting project. I look forward to doing it just because I would like to have a little family sheep farm have a digester working on a small scale in an state where only one big digester is currently in place.
 
Joshua Myrvaagnes
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Cool, keep us posted Travis.

Another thing this line of inquiry has brought to mind is the impact of animals (larger) on land, and the fact that we exclude tehm here in the city even if we're not thinking about it.  I mean, we have a high chain-link fence around the land.  We could let deer and coyotes come across our land, maybe drop a poop or two over the course of a week, and that might have a small but not negligible effect on the soil.

Well, we do have rabbit poop from a kind neighbor, but what else are we missing?  I never really thought about the fact that our fence is a sector-relating phenomenon.  I didnt' put it there, my landlord probably didnt' either, but it's there and has been for decades, and so the only poop entering our soil is from squirrrels, finches, maybe a pigeon, maybe a raccoon or possum once in a while, and worms. 

What's the viability of using human outputs for biogas?  wouldn't that add a few pounds of gas per month?

when you say "the gas output is not very high" are you referring to our compost pile?
 
Travis Johnson
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No I was referring to shear amount of BTU's.

You get the most biogas from food scraps, which makes sense, because a biogas digester is basically our stomachs in man-made mechanical form. Add food stuffs to the digester first, and you get more biogas. In my case I would be using sheep manure which has already gone through the ruminant stomach of my sheep, thus extracting half the biogas out of in in the form of...excuse the simplicity of it...sheep farts and belching. Add in some impurities with the biogas and it will not be as efficient as propane, but...

If we are using (1) barbecue tank (20 pounds) to run our cook stove a month,  40 pounds of biogas produced a month should allow us to cook as we are now I assume, with potentially a bit extra.

From a return on investment point of view, it does not really make a whole lot of sense to build a digester, but I am thinking I got the heavy equipment to do the earth work, and I think it would be good to show the community that it can be done on a smallish scale. I am thinking of keeping it kind of simple; batch making of it since we clean out the barn every 3 days, and since we live on a hill, keeping a lot of it underground to stave off our cold Maine winters.

A lot of research left to do on it, I am just rather surprised that there is not more biogas chatter on here. I am no expert and would love to collaborate with someone on a working design.
 
Roberto pokachinni
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I am also very interested in bio gas, and other forms of home made fuels/energy.  Locally we have bio-diesel being refined from vegetable oil, geothermal production at residences, lots of micro hydro, and biochar/gasification, and plenty of solar, and a bit of wind.   I was most intrigued when reading about the biodigester that Jean Pain had contained in the center of his composting shredded woody piles.  It seems like he got a great deal more gas than what you are suggesting, Travis, and this is not with veggy scraps or manure, just with shredded forest materials (both green and woody) mixed.   
 
Joshua Myrvaagnes
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They're quite common in India, I've heard, and so they probably have the kinks worked out.  11:11!
 
Rebecca Norman
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Yes biogas is fairly common in India, or has been in the past. It's generally given as a rule of thumb, that it takes about 3 cows, who stay at home all day (no pasturing), to provide enough gas for a family.

Human manure has much less biogas producution value than cow manure, for some reason, beyond the obvious huge difference in volume. Food scraps are said to be high value, so if you can collect scraps from a restaurant it could be good, but you'd have to make sure there aren't big long things that can clog up the works.

It works best when kept as warm as an animal's gut, so much warmer than the ambient temperature for most of the year in the US, though India has many places that are warm enough for most of the year. Here in the Himalayas at our school we tried it, with solar heating the tank, but we ran into other problems (we made it out of the cheapest possible materials and it didn't last). We'll do it eventually. We've got 4 cows, and are cooking for like, 100 people most of the time, but we've got solar cookers and wood burning stoves too so the biogas would be an effort to reduce or eliminate our commercial bottled gas.

It's might be a good idea to get a separate burner for the biogas in the kitchen, and keep your propane range. The burners are different, and you might want to keep the propane as a backup. I read about various ways to scrub the sulfur compounds and moisture to make your flame more efficient and your appliance last longer without rusting out too fast.
 
nancy sutton
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fyi
http://www.motherearthnews.com/renewable-energy/diy-biogas-digester-part-1-zbcz1411
http://www.motherearthnews.com/search?tags=%22David%20William%20House%22
https://www.permaculture.co.uk/videos/building-simple-two-barrel-anaerobic-digester


and you've probably already checked the 'Biogas' thread in the Energy section here.
 
Joshua Myrvaagnes
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Cool!  Do you have the SolSource cooker? do you have thermal batteries?  curious how the former perform in the Himalayas vs. here.  We seem to do better in the winter, ironically, when the air is less hazy. 

Rebecca Norman wrote:Yes biogas is fairly common in India, or has been in the past. It's generally given as a rule of thumb, that it takes about 3 cows, who stay at home all day (no pasturing), to provide enough gas for a family.

Human manure has much less biogas producution value than cow manure, for some reason, beyond the obvious huge difference in volume. Food scraps are said to be high value, so if you can collect scraps from a restaurant it could be good, but you'd have to make sure there aren't big long things that can clog up the works.

It works best when kept as warm as an animal's gut, so much warmer than the ambient temperature for most of the year in the US, though India has many places that are warm enough for most of the year. Here in the Himalayas at our school we tried it, with solar heating the tank, but we ran into other problems (we made it out of the cheapest possible materials and it didn't last). We'll do it eventually. We've got 4 cows, and are cooking for like, 100 people most of the time, but we've got solar cookers and wood burning stoves too so the biogas would be an effort to reduce or eliminate our commercial bottled gas.

It's might be a good idea to get a separate burner for the biogas in the kitchen, and keep your propane range. The burners are different, and you might want to keep the propane as a backup. I read about various ways to scrub the sulfur compounds and moisture to make your flame more efficient and your appliance last longer without rusting out too fast.
 
Rebecca Norman
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Hi Joshua,
Our solar cookers are Scheffler concentrators, and they're about 20 years old now. No thermal battery, they only work while the sun in out.
 
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