[Stoves] [biochar] Julien Winter: a soil scientist in name but not in practice.

[ajheggie at gmail.com]

[Default] On Fri, 9 May 2014 08:07:13 +0700,Crispin Pemberton-Pigott
<crispinpigott at outlook.com> wrote:

>I just saw a small internal combustion engine which runs on gas produced by a charcoal gasifier.
>
>The gasifier is about the size of a large domestic stove and holds 7 kg of charcoal or so. From what I understand so far it is a) very simple to make and operate, b) has none of the problems which make pyrolysis gas difficult to clean for use in an engine and c) will operate an engine using about 3.5 kg per hour. I will get photos.
>
>Indonesia has more than 10,000 occupied islands. Some of them have a lot of waste biomass, or just lots, or agricultural products including sawdust. Many only have diesel powered electricity.
 
>
>If the char from a stove was suitably sized by planning the system as an integrated unit, then water pumping, oil pressing and electricity generation could be performed by very simple equipment. Candle nut shells are a good candidate for this as Nurhuda has already demonstrated making good quality char from a stove.

We had this discussion in the late 90s before biochar emerged as a use
for small sizes of charcoal.

I remember discussing the Kalle gasifier, this was a WW2 device that
was basically a tin can with a central inlet which could be agitated
11RC. 

As the charcoal would tend to an equilibrium temperature over 1000C
there was a thermostatically controlled feedback path from the engine
exhaust to the inlet to keep this temperature lower as the up to 15%
of the recycled CO2 would react with the hot char and be reduced
endothermically to CO.

The resulting producer gas was chiefly CO and Nitrogen. As it largely
lacked the hydrogen of woodgas flame speeds and calorific  value were
lower, substantially reducing engine power and speed.

As you say this char could be bought from small producers and power a
simple genset or pump, displacing some diesel. Whilst it would be
naturally cleaner of tars than woodgas I suspect it would still need
more oil changes and maintenance than refined diesel.