[Cob] Joe Kennedy comments on biochar in earth ovens

[Shawn King]

Joe and Ray,

Hmmm, Joe, I like the drawer idea.  I'll keep an eye out for an old
popper, likely to work well and have a great vibe!  I'm thinking heat
loss would be a minimal issue as the heat is stored in the mass walls,
not in the air, so opening/closing won't cause much loss in most
designs, unless you are also loosing a lot of mass wall area in the
design.  My oven "breaks the rules" as the door is wider than would be
considered optimal to allow use of an earthen crock for slow cooking
stews after the bread/pizza etc. is done. It still works, but I think
I do loose a little efficiency by having a >50% door width rather than
the approx 1/3 recommended traditionally. Maybe the drawer could be
built into a metal "rocket door" type retrofit, with the drawer
sliding in above the rocket door tube.

I'm not sure how air tight the biochar unit needs to be.  The canister
is pretty well sealed except for the burner holes.  This may be key in
getting combustion to stop on its own when the pyrolysis gasses are
exhausted, a good feature IMHO.

I need to get good data on the canister method on my next firing.
Weight of the wood mass before and after char, some estimate of volume
as well, and maybe the length of time a can-full will burn gasses. I
would also like to try bamboo from local sources as a biochar fill,
see what happens. Our sycamores drop lots of small branch material
every year, twigs may just be the easiest and most available thing,
but I bet bamboo will make prettier charcoal.

Another experiment I'd like to try is a crude charcoal filter built
into the chimney, likely near the end, to filter out some of the smoke
that seems inevitable when you first fire up.  Make your own filter
charcoal!  Could be something easy, a slot in the chimney for a couple
of layers of charcoal in wire cages - maybe those old wire smore
cookers, or something of the like.  Change the charcoal out
frequently, and keep it loose in the cage for maximum air flow,
causing the exhaust to roll over and around charcoal pieces.  Even if
you only got half of the soot and other smoke nasties out of the
exhaust, it would be well worth it.

Plenty left to do!

On Mon, Apr 25, 2011 at 3:49 PM, Joseph Kennedy
<livingearth62 at hotmail.com> wrote:
> Dear Shawn and Ray,
>
> I am thinking of a biochar "cooker" that could be inserted like a drawer
> into the firing chamber and easily slid out with not too much loss of heat.
> Maybe several interchangable drawers, like old 8-tracks that could
> be slotted in and removed when the biochar is ready, with the biochar
> removed as generated during the firing of the oven.  Or maybe like those old
> fashioned popcorn poppers used in fireplaces, now that would be a cool use
> of old tech!  Gotta find me one of those to try.  Biocharpopper.
>
> Mad science for all!
>
> Best,
>
> Joe
>
>> Date: Mon, 25 Apr 2011 12:47:55 -0700
>> From: cobanation at yahoo.com
>> To: sbkingster at gmail.com; coblist at deatech.com; livingearth62 at hotmail.com
>> Subject: Re: [Cob] Joe Kennedy comments on biochar in earth ovens
>>
>> Dear Joe,
>> We just launched the Dragon Pizza Oven and it was a smash hit. We ran it
>> for five straight houts and collected at the end only a half cup of biochar.
>>
>> Regards,
>> Ray
>>
>>
>> The Great Challenges we now face as a species present the very
>> opportunities that are giving birth to Ecological, Psychological, and
>> Spiritual Sustainability.
>>
>>
>> --- On Mon, 4/25/11, Joseph Kennedy <livingearth62 at hotmail.com> wrote:
>>
>> > From: Joseph Kennedy <livingearth62 at hotmail.com>
>> > Subject: [Cob] Joe Kennedy comments on biochar in earth ovens
>> > To: sbkingster at gmail.com, coblist at deatech.com
>> > Date: Monday, April 25, 2011, 12:03 PM
>> >
>> > Dear Shawn,
>> >
>> > I have been inspired by your low-tech stuff, and am going
>> > to integrate the door design into my new oven under
>> > construction with high school students.
>> >
>> > However, it seems a waste to make biochar unless you are
>> > using that heat to heat up the oven for other purposes.
>> >
>> > To me the ideal would be to make a biochar chamber below
>> > the oven (like in Ray Cirino's example) to create efficient
>> > heat and biochar at the same time.  Any ideas on this
>> > option?  I can play around with this idea, since my
>> > oven is still under construction.
>> >
>> > I love the mad science going on!
>> >
>> > All the best,
>> >
>> > Joe Kennedy
>> >
>> > PS.  I just published an article of my earth oven
>> > odessey at Kiko Denzer's site.  It has the plans of my
>> > latest oven.
>> >
>> > http://www.handprintpress.com/ovens/an-earthen-oven-odyssey-by-joe-kennedy/
>> >
>> >
>> >
>> >
>> >
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>> >
>>
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