Mike Farmer

Bonnie Kuhlman wrote:

Mike Farmer wrote:At a small scale for animal feed, making biochar can be as easy as throwing a (clean/new) metal paint can with a few holes punched into it full of wood chunks into a backyard fire pit (or wood stove) while you have the fire. I've fed biochar to my chickens when I make it (I also add it to their bedding) and I think it's a great use for biochar (and the chicken's guts are great at inoculating biochar).

But don't you have to seal it off from oxygen after everything is burned?  Or would you just pour water on this?

Yes, sorry, the paint can is sealed, with just a few small holes to let moisture and gasses to escape.

Here's a pic of what I am talking about:

At a small scale for animal feed, making biochar can be as easy as throwing a (clean/new) metal paint can with a few holes punched into it full of wood chunks into a backyard fire pit (or wood stove) while you have the fire. I've fed biochar to my chickens when I make it (I also add it to their bedding) and I think it's a great use for biochar (and the chicken's guts are great at inoculating biochar).

I can imagine "manure slurry quench" works pretty well...also imaging the smell isn't the best!

Interesting stuff. I assume that the potential payback isn't there for backyard-scale producers, but the more we can incentivize char production at all scales, the better!

Using the heat as either heat or for drying makes a lot more sense than converting it to electricity from an efficacy standpoint. Drying lumber (while making biochar of the scraps?) or maybe drying inputs for your next char? I like it!

Kathryn Skinner wrote:Just curious. Has anyone thought about how to use the heat from making the biochar for something else? Any heat differential is possibly a source of electricity.

I've googled it, and I think it'd be technically possible...but you'd be talking about like enough power to change a cell phone, or maybe run a string of LED lights...not much more. So, if that was a scenario that'd be useful, it'd be worth exploring.

And here I've been running out to the compost pile every three beers like a dope!

Good stuff! Looking forward to your updates!

It's a great point about using materials other than logs. Stick, wood chips, and other woody biomass that you wouldn't traditionally turn in the wood stove all would be great inputs here.

You can even make char with other hard-to-dispose of things like bones, avocado pits, nut shells, and the like. I've even experimented with making char from invasives like Japanese knotweed.

Neven Curlin wrote:
I've made an image to show the 'smolder' standing upright (see attachment). The bottom half is where the to-be-charred material goes, and then the upper half slides over it.

As you can see, the side sheets extend past the bottom, so there would be some room between the bottom and the grate. The grate is at the bottom of the fire box, so a lot of ash falls through into a small container that can be removed when the grate is lifted. It's also where the air comes from (via a duct to the exterior of the house), so maybe it wouldn't be wise to drill a hole at the bottom of the 'smolder'. Maybe better at the sides, so the oxygen is consumed by the fire outside of the 'smolder'.

As it is, without holes, I think the gasses would come out where I've added the red arrow. I don't know enough about retorts as of yet, to judge whether that's fine, or whether it would be better to have holes at the top or bottom (sides).

Thank you for the additional diagram. Based on what you shared, I would agree that the gasses should off-gas from where the overlap of the top and that should work well without an extra "base".

I hear you on durability. It really depends on how cheap the other options are and how long they last. For example, food cans might be free, but only last a few burns. An empty metal paint can may cost way less than the smolder, but won't last as long. It's a balance and really "user's choice".

Whatever method you go with, please report back on how it went if you get a chance! The more sharing we can all do of our experiences making char, the better!

Neven Curlin wrote:If there are still people around who have experience with making biochar in a wood stove, I would like to ask what you think of this stainless steel 'charcoal smolder':

Would this work in a wood stove to make biochar? And also, to fit my wood stove (see attachment), it would have to stand upright. Would that work, or would it be better to drill holes somewhere (at the bottom?). It seems gases can escape through the slits between the two parts.

My 2 cents is that the device shown would likely work in a wood stove to make char assuming it fits inside the fire box. If it had to stand vertically in your wood stove, you might want to put it in upside down so the gasses come out at the bottom? Maybe standing on a small fire brick so the hole doesn't get blocked by ash? That way you'd be sure the gasses would have time to ignite before going up the chimney.

All that being said...that charcoal maker feels like massive overkill. It's 99 Euros, which is no small investment. You can easily do something with cheaper materials like Sean's use of hotel pans shown just above. I've also had good luck with clean metal paint cans with a couple of holes punched. Several other YouTubers have videos of making biochar with reused metal food cans (small or #10) with a crimping tool.

Those may be worth exploring as they're much cheaper, only take a little DIY, and free up that 99 Euro to spend elsewhere!