Alu-foil biochar

Hey everyone, I need an opinion, I want to try to make biochar using the following method: branches and small twigs wrapped in alu-foil and then loaded in a barrel full with other branches that I will lite a fire. The alu-foil wont let any air in and the wood should turn to biochar, right? Any opinions? I cant find any other metal boxes, hence the alu-foil.

[quote=Vase Angjeleski]Hey everyone, I need an opinion, I want to try to make biochar using the following method: branches and small twigs wrapped in alu-foil and then loaded in a barrel full with other branches that I will lite a fire. The alu-foil wont let any air in and the wood should turn to biochar, right? Any opinions? I cant find any other metal boxes, hence the alu-foil.[/quote]

Better off with a steel can,  Alum foil will melt at high enough temp.    Steel can with holes in bottom for gas to escape.

Better yet,  dig a hole,   burn your fire over the hole till it is all coals then cover with dirt.      Look up cone method of charcoal on youtube.

Respectully, I would never use foil for this. My experience is that there are endless free options available.

Discarded cooking pans, coffee or food cans, even paint cans can be used instead. It's hard to believe a dump or recycling centre can't provide what you need.

Many of us make large volumes of decent char with open burning in deep firepits or trenches. The trick is to keep packing the coals to exclude oxygen, and then wet and cover the hot char so it stops burning.

Hello Vase!
I agree with the other responses,  but I like your out of the box thinking.
I've thought to do the same, except coating the wood in a thick layer of clay.

There is no need to use ANY metal when making biochar, although I know that many people do. I make mine mostly in a trench in the ground. Dig the trench, a bit longer than the material you want to burn. Start the fire along the length of the bottom of the trench. Gradually add wood over an hour or so, adding more each time the flames look like they are starting to die down. When you have a layer of char in the bottom, and are out of fuel, quench the whole thing with water.

This method lets you make a lot of biochar very quickly - far more in one batch than I used to get using oil drum type methods - because you can keep adding more and more fuel to make a deeper and deeper layer of char.

Michael Cox wrote:There is no need to use ANY metal when making biochar, although I know that many people do. I make mine mostly in a trench in the ground. Dig the trench, a bit longer than the material you want to burn. Start the fire along the length of the bottom of the trench. Gradually add wood over an hour or so, adding more each time the flames look like they are starting to die down. When you have a layer of char in the bottom, and are out of fuel, quench the whole thing with water.

This method lets you make a lot of biochar very quickly - far more in one batch than I used to get using oil drum type methods - because you can keep adding more and more fuel to make a deeper and deeper layer of char.

But, I have very thin twigs, pencil-thin, wont they just turn to ash?

As they start burning they turn to char, and some ash. But as they get weakened by the heat the char drops down into the trench. Once at the bottom of the trench the oxygen can't reach it, so it stops burning away. Provided you keep adding fuel to the top the layer of char keeps building up.

It is not quite as efficient as using a retort system, because some does turn to ash, but it is really fast, really easy and you don't need to faff around with cutting material to length, or having a retort system that needs careful loading and supervising.

I burn mountains of brash like this - everything from pencil thickness up to forearm size in one fire. Just make sure it is dry, and keep steadily adding fuel until it is done.

Vase Angjeleski wrote:But, I have very thin twigs, pencil-thin, wont they just turn to ash?

I use a long pole, shovel or rake to vigorously poke the fire and pack the coals. This reduces the ash content quite a bit.

Michael Cox wrote:There is no need to use ANY metal when making biochar, although I know that many people do.  

Respectfully, it depends on what you're burning. Not all of us have wood to spare. Most of the char I make is crop debris such as bean shells. The trench method really doesn't work for that.

I agree that the volumes of the trench are more impressive, but the quality of the charcoal that I get from my retort is so much better, I haven't been able to stay away from that method.  This year I'm going to get together a huge pile of my trimmings from cutting firewood and give the trench another try.

Vase, I think like other have mentioned, your aluminum foil will burn up.

Vase,
For another viewpoint, I burn little sticks with my TLUD metal barrel that I got for free.  They don't turn to ash, because I douse them with water just before they turn to ash. It works great for my situation.  

I agree that I wouldn't use the aluminum.  

John S
PDX OR