Methods of creating biochar

John how do you create biochar?

I had been planning to make biochar for a few years, due to all the things it can do for the soil, for plants, and for climate change.  This is the first method that I saw, where I thought, "I could do that!"

https://duckduckgo.com/?t=ffab&q=Warmheart+biochar&atb=v401-1&iax=videos&ia=videos&iai=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DYIbGkmt1VdE

John S
PDX OR

Here's my (low-tech, small scale) current setup:



The trash can has 4-5 holes drilled into the side that are pointed towards the fire, so off-gasses are directed there to ignite.

Thanks Mike. I want people to see a multitude of examples of how to make biochar. This is a bit different than other methods I've seen. Thanks for showing it to everyone.
John S
PDX OR

John Suavecito wrote:Thanks Mike. I want people to see a multitude of examples of how to make biochar. This is a bit different than other methods I've seen. Thanks for showing it to everyone.
John S
PDX OR

I agree that the more we can explore and discuss the different ways of making biochar, the better. Depending on your skill level, property setup, feedstock available, and a bunch of other variables, there's a lot of different considerations for each person who may want to make biochar. One person may only be able to make a little biochar in a woodstove or a small fire pit. Others may have the room and material to do massive burn piles. Maybe they have the skills to build a retort, either simple or more complex.

So far, I used this approach to make biochar out of invasive Japanese knotweed, which worked really well. I tried a burn last weekend on a wet day with wet feed stock and fuel, and only got partial char. I will do another run on a dryer day to finish up that char and then try again soon with a burn with dry wood feedstock and dry fuel. I'll report back on how it goes.

I have a 55 gallon drum that I'd like to use similarly....although my current fire ring is a bit too small to fit the barrel in, and it didn't get hot enough when I tried sitting it on top of the fire pit.

I have started making biochar with a solar  concentrating mirror. Works great.  Minimal smoke:)

Here are photos of the setup. Pretty simple. More details are at www.wastefree23.org

What a cool idea!  I'm sure there are areas where it is practical.

John S
PDX OR

Hi all, I want to give this a try but I know very little about it. I have a large burn pile to do in the near future, and a 55g drum with locking lid. Can I just fill it up with sticks and toss it on the pile, or do I need to make holes in the barrel? Also, what would be a good source of information on how the science of this works?

There are a lot of options. It kind of depends on your location.  I live in a suburban area, so I can't just dig a trench and light it on fire. Nor can I just light a pile of sticks.

In the second post of this thread, I left a link to the method I use with a 55 gallon drum.   It was a little work to get it the set up started, but it has lasted for maybe 100 burns over many years and shows no signs of slowing down.  

Of course, you could do your variation on some of the methods you see here in the forum to most closely fit your particular property.

John S
PDX OR

Don Quixote wrote:Hi all, I want to give this a try but I know very little about it. I have a large burn pile to do in the near future, and a 55g drum with locking lid. Can I just fill it up with sticks and toss it on the pile, or do I need to make holes in the barrel? Also, what would be a good source of information on how the science of this works?

I've tried the 55 gallon drum in a fire method (I used a fire pit, with mixed results). I did drill a few holes in the barrel to let moisture and off-gasses out, but I suppose the lid and clamp likely aren't airtight, so gasses may vent there. A few holds may be good just to be safe.

If you build the pile right over your barrel and then burn it, it should work assuming your burn pile gets hot enough and burns long enough. Make sure to let the barrel cool before opening it. Also, if you douse the burn pile when it's coals, much of that material is likely char (some may be not fully charred, but much of it will be).

If you give it a try, report back on how it went, and take some pictures!

To clarify, or for those too lazy to go back in the thread and see my link,
I make a TLUD, with a chimney, so the air flows through the barrel and up through the chimney.  It's a very different method than burning in a trench or on the ground.
John S
PDX OR

John Suavecito wrote:To clarify, or for those too lazy to go back in the thread and see my link,
I make a TLUD, with a chimney, so the air flows through the barrel and up through the chimney.  It's a very different method than burning in a trench or on the ground.
John S
PDX OR

Too lazy to drill holes, but I did watch the video. 😁

I'm interested in learning about the science behind it, such as why the holes are drilled where they are and if it's even really necessary. I'm the crazy guy that generally likes to tinker with designs because I'm a fan of learning what happens. I'll try just using the closed barrel and see what happens.

One other question though, would wood chips be too densely packed for this to work well? I have literal TONS of wood chips.

Don Quixote wrote:
Too lazy to drill holes, but I did watch the video. 😁

I'm interested in learning about the science behind it, such as why the holes are drilled where they are and if it's even really necessary. I'm the crazy guy that generally likes to tinker with designs because I'm a fan of learning what happens. I'll try just using the closed barrel and see what happens.

One other question though, would wood chips be too densely packed for this to work well? I have literal TONS of wood chips.

As the biomass in the barrel heats up, it will first drive off moisture, and then flammable off-gasses as part of the pyrolysis process. You want the moisture out, and in theory the gasses could build up and cause a problem if they can't escape the barrel. I drill holes that are pointed near the fire because those gasses can actually help fuel the entire process.

The gasses may vent out the seam where the barrel is capped. If you look at the picture above with the trash can in the fire pit, you can see flames at the lid seam, where gasses were clearly escaping.

Hope that helps!

Don Quixote wrote: I'm the crazy guy that generally likes to tinker with designs because I'm a fan of learning what happens. I'll try just using the closed barrel and see what happens.

One other question though, would wood chips be too densely packed for this to work well? I have literal TONS of wood chips.

Senor Quixote:  I think we're all that crazy guy (or gal, or ? these days)

The holes in the bottom are so the air flows past the wood, as Mike was saying, and burns the gases off of the wood as it is heated.  When the gases are burned off in the TLUD, it's time to quench the fire, which blows up the char more and activates it.  

Wood chips are usually not a good idea in a TLUD, because the air can't really flow through them. They are too dense.  I have set up the wood to be burned and poured SOME wood chips over the fire. It was ok, but I didn't put too much in.

John S
PDX OR

"The holes in the bottom are so the air flows past the wood, as Mike was saying, and burns the gases off of the wood as it is heated.  When the gases are burned off in the TLUD, it's time to quench the fire, which blows up the char more and activates it."

Ok, is it necessary to quench the barrel, or can I just let it start until the bonfire burns out?

You want char, not ash. If you don't quench it, it will all turn into ash, unless you have a retort.   Ash is useful, unless you have alkaline soil, but it is nothing like biochar.  When you quench the biochar, you also activate it, making it puffed up and better as housing for microbes.  In the video, they weren't very helpful about when to quench it.  I quench it when the flames have gone down to only about 5-8" above the char. That's when I get the most char and the least ash.  

John S
PDX OR