[Cob] Joe Kennedy comments on biochar in earth ovens

[Dulane]

I love your new designs. It is great to see these clever people taking the
next step. I didn't consider the biochar factor when I built my stove, but
the front of my firebox is stacked brick which I can reconfigure.

If I redesign my rocket oven, I will definitely include a pot warmer,
because sometimes you want steamed veggies.

And I certainly believe that having your fire under your oven area and
having a metal oven floor reduces the time/fuel for cooking. In my case, I
will always have expansion cracks where the metal and cob and brick meet,
but I don't get any smoke leakage.

I use around one 5 gallon bucket of fallen tree branches to fire my oven and
can cook an entire meal in an hour and 15 minutes. I haven't tried breads,
but muffins cook well. I have to put a metal grate down on the steel floor
to keep the bottoms of the muffins from getting too hot...but meats and fish
get done quickly especially if they are turned over. I wonder if my large
stainless steel bowl (interior oven top) reflects heat or if the cob behind
it radiates the heat back through the metal? Using covered casserole dishes
and oven grates allows me to regulate heat too. I do need a better door.  

I have to babysit the fire pretty much (don't leave for more than 5
minutes), and have all my food ready-to-go unless someone else is tending my
fire. My partner over stoked it recently, and flames came out the front
instead of the chimney. It near broke my heart, but luckily cob cleans up
well if it isn't totally charred.

One loss from the old stove design that I have noticed...I cannot stay warm
in front of the oven when it is cold outside. My oven throws very little
heat except over the chimney. So winter time cooking isn't quite as much fun
as it used to be.

Dulane   


To: sbkingster at gmail.com
Cc: coblist at deatech.com; Albert Bates
Subject: Re: [Cob] Joe Kennedy comments on biochar in earth ovens


Hi Shawn,
 
I am thinking to create a biochar drawer that would fit in the lower slot of
your rocket door.  In my design, I think the gases would ignite, even though
the main fire will be in the chamber below.
 
I like the carbon scrubber.  I am planning to make a chimney plug of a
ceramic flower pot filled with vermiculite cob.  I could use the same size
flower pot to form carbon plugs with chicken wire and biochar (i.e
charcoal).  I am also thinking of vermiculite cob to make the oven door per
your design.
 
All the best,
 
Joe
 
> Date: Mon, 25 Apr 2011 16:48:39 -0700
> From: sbkingster at gmail.com
> To: livingearth62 at hotmail.com
> CC: coblist at deatech.com; albert at thefarm.org
> Subject: Re: [Cob] Joe Kennedy comments on biochar in earth ovens
> 
> 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/
> >> >
> >> >
> >> >
> >> >
> >> >
> >> > _______________________________________________
> >> > Coblist mailing list
> >> > Coblist at deatech.com
> >> > http://www.deatech.com/mailman/listinfo/coblist
> >> >
> >>
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> 
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