Backyard Smoke: What to do with the biogas from making char

[Philip Small]

Making char produces biogas. It is flammable and contains a prodigious amount of energy. In an industrial setting char-making strategies often rely on the value of that energy, using it to produce hydrogen, etc.

It appears to me that the commercial value of the released biogas approaches the commercial value of the char produced. We who frequent this forum should not be letting this value slip away, allowing it to contribute to greenhouse gases, without some attention to the potential for recovery.

In the typical backyard/rural lot setting of the terra preta tinkerer, reasonable options for using the heat and smoke produced are below the metaphorical horizon or a "back burner" issue at best. Hopefully this thread will help stimulate some initial discussion in this area.

To date, I have found two technologies that offer some reason to hope that solutions could be developed at the individual household level:

1) The inverted downdraft gasifier. Developed to make more efficient use of wood for cooking in developing countries, it is undergoing continuing refinement. Many DIY-type folks are trying their hand at various configurations (The Garlington, the Magh smoke burner stove. The MIDGE (pdf). The James Butler MIDGE). It is a small batch process. It is highly efficient: a handful of twigs will boil a cup of water. The process is shut down about halfway through the burn sequence in order to retain the char.

2) At the high tech - glimmer-in the eye end of the visualization spectrum: The Stirling engine. A highly efficient, fairly simple, external combustion engine, the Stirling engine is far safer than the steam engine. The Strirling being applied to generating electricity from industrial waste heat, to generating electricity from solar heat, to cogeneration of household heat and electricity, and to service as a wood stove top circulating fan. A demo stirling can be made from tin cans and plywood, but a machinist in the family could be quite handy.

Look forward to seeing folks build on this theme of using the smoke and the heat generated in some beneficial way.

[Turtle]

Originally Posted by Philip Small

Making char produces biogas. It is flammable and contains a prodigious amount of energy. ...

Look forward to seeing folks build on this theme of using the smoke and the heat generated in some beneficial way.

Great post Phil! I have in mind to build a small stove from cans, etcetera, and the plans you linked were helpful. I have more the intent to have a lightweight camp/emergency stove that I can continually feed, but it prompted me to think of how to use it to make charcoal as well.

On top of a wood stove of your choice, set a cast iron pot with lid, charged with the bio-mass intended for charcoalization. In preparation before burning, drill a hole in the cast-iron post lid and install a fitting for copper tubing (1/4" oughta do for a small setup), and affix tubing so it exits the pot and enters the stove secondary intake. Fire it up! Voila! Charcoal and you have recaptured and burned the gases you created.

[Michaelangelica]

Originally Posted by Philip Small

Look forward to seeing folks build on this theme of using the smoke and the heat generated in some beneficial way.

thanks Phillip.
I came away from the IAI conference feeling that commercial pyrolysis is still away off. No-one wants to be first. All the engineering problems have been done. Now the bean-counters are doing their sums. Using of course, economic models that have always been suspect and poorly predictive. (GW? Whats that? Just a runaway train that is about to mow you down, thats all)
There is a recent article in the Economist apparently that suggests we cut down all the trees. I think the guy has been smoking too much "supply and demand"
I now know why I gave up studding economics - despite topping my school in it.

Anyway, I feel that we all need to be able to make our own charcoal.
Let the pyrolysis char makers worry about their markets when they finally consider them. We don't have time to wait.

So the problem becomes one of what do you do with dixonis and other poisonous bio-gasses in a home burn situation.
You obviously need to collect them or burn them.
Biogasses probably also contain a lot of oily resssiny material that is important to soil microbial life. So it would be nice to keep these.
Gary Larson has a STOVES list that might be helpful (same place as Terra preta list-bio energy lists).
I have been told by experts that it is possible to make your own char with not much more pollution than starting up an SUV.
There was a guy at the IAI Conference with a char maker about the size of a little fish-smoking box. I have to track him down. He was surrounded by people when I tried to talk to him.
I will certainly be looking at ways of making my own char this year.

[diazotrophicus]

Originally Posted by Michaelangelica

thanks Phillip.
I came away from the IAI conference feeling that commercial pyrolysis is still away off. No-one wants to be first. All the engineering problems have been done.
I will certainly be looking at ways of making my own char this year.

Hi,
Dr. A.D. Karve in India at arti-india.org has some nice machines or devices for precisely that problem. Works with leaves and other small fry.
diazotrophicus

[Turtle]

Originally Posted by diazotrophicus

Hi,
Dr. A.D. Karve in India at arti-india.org has some nice machines or devices for precisely that problem. Works with leaves and other small fry.
diazotrophicus

Thanks diaz. Good looking page with helpful info and international flavor. >> ARTI