Re: Pull embers from three-stone cookstove to use as biochar.
Paul S Anderson
1. I refer here to your statement: “… why are we so excited about biochar when the alternative of using charcoal is so close at hand?”
In common usage the word “charcoal” CAN refer to all types of chars (regarding temp at time of production and different equipment) ranging from low-temp to medium temp to high temp (think of activated charcoal made in special equipment). And all types have their uses / advantages. So, when there is no designation of low, medium or high, the word “charcoal” is insufficient. So the word “biochar” (once proposed to be “agrichar” but it was somebody’s trademark) was created, initially regrading chars (charcoal) that was appropriate for placement into soils. More recently it is also for chars into construction materials and other long-term sequestration destinations (which maybe should have a separate name, but that is a different discussion.)
So, to compare “charcoal” with “biochar” means comparing one Undefined charcoal vs. one that is defined. Better to be called “low-temp charcoal” or “commonly made charcoal” or maybe some other name, but not just unspecified charcoal.
2. Your other phrase raises a question about: “ … the problem with charcoal is that it never gets hot enough (a) to burn out all of the tars and other aromatics and (b) to form the carbons into the necessary sheets of ring structures.”
I would say that the problem with “common charcoal” (as taken from an open fire, including rock-bed fires) is that it gets TOO hot at its edges of the piece of biomass because of extra oxygen (more than needed for pyrolysis) reaching the outer layer of created charcoal, resulting in some (more than minimal) combustion of the charcoal (char combustion or char-gasification that leaves behind ash). And this happens before the pyrolysis is completed in the interior of that piece of biomass.
Certainly this occurs, so the question is about the timing of the removal of the embers from the fire (or the quenching of the fire). Too soon and there is much (more than desired) LOW-temp char or even torrefied wood or raw wood in the middle of ember. Too late and there is much (more than desired) ash on the outside, with the ash falling off so it might not be seen or weighed (but such a small weight that it would hardly be included in the careful calculations of weight).
About weight (could be grams or kg or pounds): If a biomass piece of wood is 100 gm, the well-made mid-temp biochar is about 20 grams% , and the “only ash” weight is 1 gm. [Typical wood pellets are sold claiming less than 1% ash.]
3. Comment: Yes, there are differences between chars (I prefer to say chars instead for charcoal) made in “open fires” compared to those made in arrangements with constrained oxygen supply, ranging in order from open-top flame-cap (trenches, troughs, cones, etc.) and (mostly) covered flame-cap (RoCC kiln), to TLUD with limited air flow, to sealed retorts. And each degree of air control adds an amount of expense or required labor. All have their places and roles and resultant chars. Are the differences worth the efforts and expenses? Subject to the desires of the involved people and their resources (labor, money, time, biomass, etc.)
I am sure that the Amazonian Indians of 500 to 4000 years ago did not speak in terms of oxygen and pyrolysis, but they could have understood about quenching chars having advantages. Using simple practices largely unknown to us, they left behind for us the “terra preta” soils. Unfortunately, modern society does not have thousands of years to build its soils.
Doc / Dr TLUD / Paul S. Anderson, PhD --- Website: www.drtlud.com
Email: psanders@... Skype: paultlud
Phone: Office: 309-452-7072 Mobile & WhatsApp: 309-531-4434
Exec. Dir. of Juntos Energy Solutions NFP Go to: www.JuntosNFP.org
Inventor of RoCC kilns and author of Biochar white paper : See www.woodgas.energy/resources
Author of “A Capitalist Carol” (free digital copies at www.capitalism21.org)
with pages 88 – 94 about solving the world crisis for clean cookstoves.
From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of d.michael.shafer@... via groups.io
Sent: Sunday, March 28, 2021 3:40 AM
To: Ronal Larson <rongretlarson@...>
Cc: K McLean <kmclean56@...>; Biochar Listserv <Biochar@groups.io>; Stephen Joseph <joey.stephen@...>
Subject: Re: [Biochar] Pull embers from three-stone cookstove to use as biochar.
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Would be very interested in results. My understanding is that the problem with charcoal is that it never gets hot enough (a) to burn out all of the tars and other aromatics and (b) to form the carbons into the necessary sheets of ring structures. If this is not true, why are we so excited about biochar when the alternative of using charcoal is so close at hand?
On Sun, Mar 28, 2021 at 8:18 AM Ronal Larson <rongretlarson@...> wrote: