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  • From: "Lawrence F. London, Jr." <venaurafarm@bellsouth.net>
  • To: permaculture@lists.ibiblio.org
  • Subject: Re: [permaculture] Bio digester percieved dangers
  • Date: Fri, 27 May 2011 21:16:15 -0400

On 5/25/2011 3:42 PM, DGilsen@aol.com wrote:
Hi there guys I have used a biogas digester off and on for years. They
use them on poor farms built by undereducated farmers in India and they make
there biogas plants out of brick. I had kids and so I dug a pit and placed
the tank I used in there. Even with five kids and a neighbor hood full of
vandals I never had a problem. Bio gas is very forgiving, but even when
the kids fooled with my system I never had any problems. Those kids heard
form my kids that I was cooking and heating my water with farts. They opened
valves and fooled with every valve they could they ripped off the hoses
and pipes to smell the "farts"! and no explosions!They drained my gas tank
several times to the air. Finally I called all the kids and parents in the
neighbor hood and we had a "class" on the biogas system I had and finally
the little turkeys quit screwing around with my biogas tanks I also fenced
it off to limit access.

Bio gas is explosive but not as bad as I have heard it was, and if any
system should have exploded mine should have ,but it didn't Don't worry
about it. Place the storage tank in a pit and fence it off, with chain link.
If it does explode the explosion is directed upward .
Carol

To back you up, Carol, here is feedback from David House; take note of the last paragraph about not installing the tank in the ground (unless it is really well insulated with spray-on hard-setting waterproof foam insulation - then again animals and insects may degrade it - my suggestion). - LL

-------- Original Message --------
Subject: Re: [permaculture] Bio digester percieved dangers
Date: Thu, 26 May 2011 18:27:25 -0700
From: David <david@h4c.org>

I have been surprised in the workshops that I have given to learn that
many folks don't realize that biogas/methane *cannot* explode /unless/
it is mixed with air. Calling biogas/methane "explosive" is likely the
source of confusion.

Plan old water, after all, is *explosive*, if it is heated up enough--
plenty of boilers have exploded, after all-- and it is in fact water
that caused the explosion at the Japanese nuclear reactor. (What
happened there, however, was only partially a steam explosion. It was
primarily caused by the fact that at very high temperatures, water
disassociates into hydrogen and oxygen, and /that/ mixture explodes.)

So my point, again, is that biogas *cannot* explode, *will not* explode, and will not even /burn/ (!), unless it is mixed with air/oxygen. If folks would keep a positive pressure in their biogas systems, then such explosive mixtures very rarely occur, and then only in the air surrounding the digester, not in the digester itself.

As a final point, I would not suggest putting a biogas tank in the
ground, if you have a tank. It just steals heat from it, in temperate
climates.

d.
--
David William House
"The Complete Biogas Handbook" |www.completebiogas.com|
/Vahid Biogas/, an alternative energy consultancy |www.vahidbiogas.com

|
"Make no search for water. But find thirst,
And water from the very ground will burst."
(Rumi, a Persian mystic poet, quoted in /Delight of Hearts/, p. 77)

http://bahai.us/




  • Re: [permaculture] Bio digester percieved dangers, Lawrence F. London, Jr., 05/27/2011

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