methane digester advice??? :)

[catfihhunter90]

Hey yall! Im new to the site and looking for advice and coversation with like minded people!
So I am designing a % 100 self sustainable underground surthrival bunker.
One feature I am designing is a methane digester. I understand the basic concept but I have some issues I am still working though.
Here is my scenario:
The digester must be able to handle the work load of:
10 people's human waste.
10 rabbits waste.
10 chickens waste.
20 quails waste.
And kitchen scraps.
im looking to be able to use this system indefinitely with routine maintenance of course.

The gas will be used for heating, cooking and potential clothing and bedding drying.

Has anyone here ever designed a system of this size and or know of a good web resorce or company?

Thanks in advance folks!

[wsxian2]

when in doubt turn to mother earth

Mother Earth has a site:
Homemade Natural Gas: The MOTHER EARTH NEWS Methane Digester - Renewable Energy - MOTHER EARTH NEWS

Does anybody remember the Whole Earth Catalog?

Boy does that bring back memories. The internet in print....

[dutchdivco]

Just my thoughts,..

And yeah, this brings back memories for me,....too! I should think you would want to go with a 'batch fed' rather than 'continuous feed' type of system. In many ways, thats a much 'simpler' system. Just need a cotainer which you can 'seal', air-tight, so you get anerobic, (without oxygen) rather than aerobic (with oxygen).
One basic design I saw just used a 55 gal drum, with a 30 gal drum turned upside down in it. You fill the larger drum say,...1/2 full with crap, (with enough water, (I don't remember whether you need to check/adjust the ph level, and don't know whetehr you need to 'seed' the batch with bacteria or not) then set the smaller drum upside down inside it. The smaller drum is your gas resevoir; as the gas develops, it fills and begins to lift the smaller drum.
Tap off of it with a line, and basic plumbing from there on out. If you need to raise the pressure, can put weight or springs on the smaller drum to increase the pressure.
You COULD use something like a sink with a garbage disposal; you dump all your various crap into the sink, add water if necesary, then run the garbage disposal to chop/mix and push the stuff into the larger drum. Or, you could save the electricity by doing it with manual labor.
Use the old KISS principle, and keep it simple. One thing to bear in mind, during a 'survival' situation; time and effort is DIFFERENT; compared to the way most of us live now, there is lots of 'time on your hands', with not a lot to do, so doing things in what we now think of as a 'labor intensive' way isn't such a bad thing; keeps people from moping, to give them something to do.
Seriously, the way we view time is very different to say,...100 years ago.
Anyway, good luck with your project. You could start even smaller, for early experiments, wit say a 5 gallon jug. Make SOME gas, using your 'fuel' mix in roughly the proportions you figure you'll be working with, and then scale up.
Maybe 2 digesters; so you can stagger the time of emptying and filling, and have some production going on all the time? Expending energy to compress the gas for storage would be impractical, I think. Waterbed mattresses, weather balloons, are both possible storage options. Jim