I'm late to the party here, I know, but I gotta say this seems like a big deal? If I understand correctly, this is like a
rocket stove but it leaves behind a pile of nice charcoal? The book doesn't go out of it's way to make it easy to understand, but from what I gather it's like this: when you burn
wood it doesn't burn directly, instead there's a process:
The wood must dry out first. Moisture is driven out by the heat of the starting flame.Pyrolysis - the solid dry wood is converted into gas and char. These are what burn: the gases and the charcoal.The gases mix with oxygen and can now combust.
The first two stages, drying and
pyrolysis, are
endothermic reactions, they take
energy. The latter stage, when the gasses from the wood mix with the air and become flame, is
exothermic, it releases energy,
enough to dry and "pyrolyse" more wood. The leftover charcoal is (of
course) nearly pure
carbon and can be burned or used for
biochar.
That's just the idea behind wood gasification, yeah? By heating the wood one place and burning the gases another you get a more efficient and cleaner process than just burning the wood the old fashioned way. The innovation described in the book is
micro-gasifiers that are simple enough to build out of a few bits of junk and small enough to work as home stoves. They burn cleaner, and they produce charcoal as a side effect, which e.g. families can
sell or use themselves.
The basic design is like a
rocket stove, but instead of the feeder chamber (sorry if I get the jargon wrong) being off to the side it is vertically inline with the gas burning chamber above it. You prime the stove by putting wood sticks vertically in the lower chamber and topping them with
kindling. There are air intakes at the bottom of the lower chamber, and between the lower and upper chambers. The lower air intakes provide oxygen to the
feed wood, and the upper intakes provide (more) oxygen to the gas burning chamber. You light the kindling and that starts a "wave" of drying and pyrolysis at the top of the feeder wood which then burns down through it like a candle, leaving behind a pile of charcoal. The gas goes into the upper chamber, mixes with air from the upper intakes, and you get a nice gas stove.
And that's about it. It's so simple that I feel like I over-explained it. Apologies if this is common knowledge here and I'm just repeating it. I just found out last night and I got really excited.
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