Containers for making biochar inside a wood burning stove?

i admit that i have never used biochar but in terms of producing it, what about a butane gas cylinder, either the ones used for domestic cooking or smaller ones used for camping. the steel is definitely strong enough to last. if its cut  into a large piece maybe 80% of the total volume, the remaining 20% would be used as a top. The larger lower part would have its top bent in to allow the other piece to sit on top in the form of a cap or lid.

Yes, like others have said, biochar is when you burn the wood or other material so that all of the oils, aromas, and volatile compounds are gone and it is just a light, easily crunchable black piece of carbon, which is now usable for microbe hotels.  There is no wood left in it either, so it's not good for barbeques.  

I just use a 55 gallon steel drum I got for free. I made it into a TLUD. I've made 30 or so burns with it. No sign of wear.  

I drench the fire when the tiny flames are just barely above the charcoal, like one or two inches above.  
Very little smoke, great biochar, very little ash.

JohN S
PDX OR

Thank you guys! We own an old heavy duty pressure cooker, like this one, but much older. Bought it used at an antique store, thought we might ahve gotten a bargain, but it's not water tight. Of course, that means it's also NOT air tight. All I have to do now is figure out where to cook it. It's way too tall for our wood stove.

Jennie Little wrote: All I have to do now is figure out where to cook it. It's way too tall for our wood stove.

What would be the ideal dimensions for your stove? Print it up and post at your local bulletin boards{church?} for a trade{this comes from the tale of Ali Baba and the Forty Thieves - fiction is useful}. Specify that it is unrepairable as a pressure cooker. I always make it a point to highlight the dangers or shortcomings up front. I can't shake this particular habit/compulsion/obsession. If you are lucky, you can join the ranks of biochareers very soon. You might even convert the other party. Mention biochar in your notice. If people understand the purpose they might make more effort to rummage through their kitchen. If you run out of fuel, I understand there is a surplus of used clothing in the USA. Make charcloth and offer it to outdoorsmen and women.  I missed the too tall bit. Ask around for anyone handy with an angle grinder. That should do the trick then.

Charli Wilson wrote:Not much help I'm afraid but I do the same thing! Old tins with a few small holes in or a not-quite-closed lid. As you do, I get through tins quite quickly- I collect the chocolate tins that float around the office at christmas and use those- but I'll be interested if you do find a better method that produces less burnt out tins.

I teach school.  The kitchen here is nice enough to save me large cans.  The batches are small, but, I can make a lot of them.
I have my chemistry students make small batches of biochar.  After testing the batches, I mix it with manure a local farmer gives me.
Then, the biology students use that "Fertilized" biochar in their potting mix to grow herbs.  They grew the same herbs in the special potting mix and store bought potting mix.  Our special mix performed just as well and cost less.
One year the cooking class did 2 batches of the same recipe so we could have a taste test.  Nobody could taste the difference between our "Poop" herbs and the Miracle Grow herbs.

Could this be done with steel barrels?
If so hit up your local car dealerships we have to pay to get rid of 55gal. Barrels that motor oil came in and 5 gal. steel barrels that brake fluid cleaner comes in.
If you try remember oil is flamable.
and the cleaner is like gasoline.

Terry Austin wrote:Could this be done with steel barrels?
If so hit up your local car dealerships we have to pay to get rid of 55gal. Barrels that motor oil came in and 5 gal. steel barrels that brake fluid cleaner comes in.
If you try remember oil is flamable.
and the cleaner is like gasoline.

I've seen video of biochar being made in a 20 gallon drum turned upside down in a 55 gallon drum.
I haven't done that size batch myself.  I've done lots of batches using a quart can inside a gallon can.

Edward Lye wrote:

Emilie McVey wrote:Showing my ignorance here: what's the difference between charcoal and biochar?  I thought biochar is simply charcoal that has been inoculated with helpful microscopic organisms.

Wood does not burn. It is the escaping gases that burn. The process continues until you get a lump of red glowing ember that produces no flame even when you fan it really hard{another way to tell is if you see white ash appearing on its surface}. .

I found this web site that answers many questions like Emilie asked.
https://thegardenteacher.com/how-to-make-biochar-fertilizer/

Paul;

Been working on this idea for making biochar for some time. First, get yourself an old ammo can from an army surplus store. Second, remove the rubber gasket inside the lid with a screwdriver. Third put it in the wood stove and make biochar.

In my direct experience you do not need to grind the biochar or make it smaller. The chunks that come out of the ammo can are perfect for going right into your garden. Just be sure you fertilize the garden according to a soil test. If you do not fertilize the garden properly, the biochar will absorb most of the available plant nutrients and depress crop production. That said, it takes a full five years for biochar to mature the microbiology in the soil. First year you won't see much change. Second year things look a little better. Third year things look significantly better. Fourth year crops really start to grow. Fifth year you will realize every row is placed too close together and every plant too close together. Sixth year, you will begin to think you're a first-class organic grower.

Uncle Bob is not my uncle.

Norm

Hi All
I happen to see your biochar tread and though surely there must be others how have similar interests .I am thinking of (concocting) experimenting  a rocket batch heater with a charcoal compartment .Being a amateur blacksmith that produce charcoal how hate to see all those BTU wasted in the process .Living in Quebec where I need to manage wood stoves 150days +- yearly. I taught there must be a way to use a rocket batch heater to produce charcoal while heating at the same time ?¿?. I manage to produce charcoal 3 to 4 times a week outdoors in to 30 gallons steel drums when ever the weather conditions are favourable. My concern is how to manage the extra heat during the charcoal (pyrolysis) gas burning process that can easily last ¾h to1¾ depending on the wood used and burning conditions.
Any ideas or suggestions regarding this matter would be great.
Thanks for your attention.
Gil

Www.southlondonpermaculture.com/gardening.html
You'll find my bulk method here

Merlyn Peter wrote:Www.southlondonpermaculture.com/gardening.html
You'll find my bulk method here

Hi Merlyn, welcome to Permies.

There’s a button bar above the text box that has a URL button. You can use it to make proper links. Maybe you could share a few details here on your method rather than just post a link? Thanks

Merlyn Peter wrote:Www.southlondonpermaculture.com/gardening.html
You'll find my bulk method here

Here is the direct link to Merlyn's biochar method.  South London Permaculture - Biochar

Merlyn Peter wrote:Www.southlondonpermaculture.com/gardening.html
You'll find my bulk method here

You seem to use the terms biochar and charcoal interchangeably.

I have my ARS-C method that makes biochar continuously in a rocket
stove inspired setup. It switches off in the time it takes for you to
go for a pee. There is a video near the end of the thread. When I
crush it and get my hands covered, it washes off. Crushed charcoal
on the other hand remains on your hands after attempts to rinse it off.
This is because of the oils, creosote and organic compounds that still
remain.

I have yet to post another thread about a loosely-enclosed-stainless-steel-container-retort
for making biochar. This is intended for seashells, prawn shells, egg shells, snail shells,
crab shells, soup bones, chicken bones, thorny branches, cutting board wood, corn cob,
coconut shells, fruit rind like mangosteen and mouldy material like nuts and dishcloths.
These don't compost well. I know because I have unearthed my old compost heaps.

The ARS-C works best with branches and stick-like wood pieces and this other
method handles the rest. There is nothing leftover for the garbage collectors.

The ARS-C is more efficient in that there is little ash left over. All the fuel turns
into biochar and you don't make more heat than necessary.

The retort uses wood as fuel and this converts into white ash overnight
when left to cool. It takes a lot more fuel simply because you can't see
when you are done. My contents vary in composition so you need extra fuel
in case the escaping fumes still burn or smoke. A bad burn could reach 2 hours+
when a good one takes 90 minutes and hardly any intervention - just fire and
forget. My best tip is to buy a jigsaw and cut all your wood from pallets and
branches into sizes of half a bar of soap until a full size.
It was a game changer for me. I use an old car battery as a sawhorse. Now I
get sawdust to experiment with.

A corn cob interior can survive the ARS-C but carbonize all the way through
in the stainless-steel-retort. I know because I crush all my biochar with
a rolling pin and sieve the powder. After using this eggshell rich biochar,
I finally got more than one fruit per tomato plant. Maybe just a coincidence.

These are tried and trusted methods from Thailand for making charcoal:

I'm a townie, only 1/4acre lot in California but trying my best to cultivate our own little microcosm.  Inspired by Edible Acres biochar videos, this is my favorite system on our property... Peach pits (or any other 'hardwood' pits that still have fruit clinging to them) go into a screen in the worm bin.  Worms take care of the leftover fruit, screen makes it easy to pull the pits out.  Pits (or other hardwood bits) go into a graniteware pot with lid (purchased at the thrift store) into the Chofu (wood fired water heater) that heats our outdoor soaking tub.  The last 10minutes of heating time, the pot goes in and charcoal is created.  Not massive amounts, but significant enough for our little production.  We enjoy the evening soak in the tub.  The next day or so, the charcoal is put into a metal bucket to be sure it is good and cool.  When I get a nice collection, the charcoal goes into the deep litter chicken run (and now our goat pen too!) to get inoculated.  Twice a year, I pull the deep litter (now enriched with biochar) from the chicken run (goats are new, not sure what that schedule will be) and put it in our garden beds to feed the fruit trees (and veggie beds) to grow more peaches to have more pits to go into the worm bin.  How's that for stacking functions?!  So tickled!  Oh...and when we drain the tub (its a bathtub I picked up off of craigslist, dressed up with discard redwood fencing from our local fencer), it drains to the swale that waters the front garden.

Ooooh, eggshells.  We feed our girls' eggshells back to them for the calcium, but the neighbors like to contribute their store bought shells to our efforts.  We hesitate to feed them to our girls before we solarize them, but I could just biochar them instead.  I like it!  And crab shells...a couple years ago I collected the buckets from the crab feed fundraiser, dried the shells in my oven (not the greatest smell over that whole process), crushed them with a $3 thrift store blender.  A whole lotta work.  I could just biochar them instead.  Thanks for the new ideas!  I don't crush the char, I just throw it in the run and stomp it a few times if anything is big-ish (bar soap size) and let the girls break up the rest.  Black walnut shells take a while to become unrecognizable...but they do disappear,

Look up gastronorm containers (or hotel pans) that come in various sizes. This is something we do and Sean Dembrosky at Edible Acres uses the same similar method, he's got one of his brilliant vids here -  

No one has mentioned roasting pans.  I had 2 old ones different sizes just used for storing things in.  I believe roasting pans are enamel (glass) on steel and they work very well.  I use them in a cast iron stove and just let them cool when the fire goes out so they don't warp.  The lid does not have to be fastened down;  the weight keeps it down enough so flames or oxygen cannot get in but expanding gasses lift it enough to have a ring of burning gas all around the pan.  The larger one I tie together with string just to get it through the too small opening and set in on the wood laid out level ready to burn.  Roasting pans have a high molded lid  and I fill the pan heaping high before setting on the lid.

Yesterday I did a pan full of old walnuts and eaten pine cones cleaned out of a squirrel infested shed.  They both made very nice biochar.  All second hand shops have fairly cheap roasting pans but they also throw out many that are too dirty or scratched to sell...

Ray

Yes, roasting pans, this is the graniteware pan I mention above.  Thanks for the suggestion of pinecones to biochar.  We have a stack of them we used to use to keep the neighbor cats from scratching in our veggie beds.  Grew quite a few pine seedlings this way...but didn't have a use for pine trees in our veggie beds.... now the movable fence I put up to keep the chickens out of the veggie beds (because the chickens just laughed at the idea of pine cones keeping them out) seems to be doing a good job of keeping the neighbor cats out also.

Here, every year, at least one, if not several, orchardist pulls a hundred acres of fruit wood and burns it.  One fellow used a cat to create a large, shallow pit to throw the wood in, then lit it and, once it was going, buried it to smolder.  

This, like others experiences, produced a lot of mixed results, but the end product was worth it and there was a lot of potential to the process.

A pit or pile burn can be managed to produce biochar, but the best process leans toward a hot and efficient fire:

Like this

and this

Burying a pile of burning wood and letting it smolder is an air quality disaster and the charcoal produced at low temperatures won't have the porosity and longevity in soil...I would not even call it biochar. We need the high heat to drive out and convert all the volatile tars and oils that are products of incomplete combustion.

Edward Lye wrote:WARNING some wood/trees/organics give off toxic fumes when burnt. The Manchineel tree is but one example.

Possibly even more likely to encounter than Manchineel is Oleander. People have died from using green Oleander twigs to cook hotdogs over a picnic fire.
It takes just an extra moment or two to research your intended char source.

You might also just want to ensure that fumes are not getting into your air supply regardless of the material you are charring. Seems the best approach.  

I use 55 gallon drum on there side. i cut a rectangle the length of the barrel and about a foot wide. i start the fire and keep choking it out threw out the day.  i have a large cherry orchard that is glad to have me take there wood. i got my idea from this video. it takes me about 18 hours to fill my drum, but it is a lot of charcoal afterwards

https://www.youtube.com/watch?v=vAJt5tGwNVM

New to the forum, first post to an older thread, but wanted to share that I've seen hotel pans used in both fire pits and wood stoves to make biochar. I actually just bought a couple hotel pans to give my father to use in his wood stove for this purpose.

Metal paint cans with a few holes punched/drilled work as well, although I expect they wouldn't last all that long.

Hi Mike,  

Welcome to Permies.

Mike wrote: I actually just bought a couple hotel pans to give my father to use in his wood stove for this purpose.

It looks from the picture as that hotel pan is narrower in the long axis than the ones Hubby bought me. I suspect that would be easier to use in a wood stove for sure, as ours take up a lot of space, making it harder to get a thorough burn.

and wrote:

Metal paint cans with a few holes punched/drilled work as well, although I expect they wouldn't last all that long.

Harder to clean before using, and definitely don't last long before burning through. I'm much happier with the hotel pans.

Jay Angler wrote:It looks from the picture as that hotel pan is narrower in the long axis than the ones Hubby bought me. I suspect that would be easier to use in a wood stove for sure, as ours take up a lot of space, making it harder to get a thorough burn.

Yes, I specifically bought that size as it looked it like it'd hold a decent amount of material (relatively speaking), but not take up a ton of space in a wood stove or fire pit. I believe these were "6 inch, 1/3 pan" sized, meaning they are 6 inches tall and take up 1/3 of a standard hotel pan. The two-pack I just bought for my father cost $30 on Amazon.

Jay Angler wrote:Harder to clean before using, and definitely don't last long before burning through. I'm much happier with the hotel pans.

Yes, I cheated and bought new, unused metal paint cans just for this purpose. They've lasted a half dozen or so burns so far...although they're starting to look a big beat up.

I've been using shallower and narrower versions  (1/4 size, 6.5 cm depth) of the stainless pans for quite some time now. I can put up to three in the fire at a time. I get two complete five-month fire seasons out of the pans before the bottoms crack and fall apart, but the tops last much longer.

I came across this video series: How to Make Biochar at Home using a 55 Gallon Drum and a 30 Gallon Drum

https://youtu.be/svNg5w7WY0k?si=eG_8B6Xp6EuGaKF7

Before I had any other kiln options, I experimented with making small batches in a ceramic cauldron, inside a wood-burning pizza oven. Worked OK. Better results than my first batch in a 55gal drum.

David the Good referenced this video about using soup cans/ any cans with a crimping tool to make charcoal retorts in about 1 minute, which can then be tossed into any fire:

I also saw the video that David the Good referred to and made a few cans. I found that sawdust packed into them makes a quite decent amount. I’m not sure how long the candy will last but we throw away big cans almost weekly  at our church from meals so I have an almost unlimited supply. So far I’m really thrilled with it. Easy, fast and a constant small supply to throw into the chicken coop (deep litter method) along with my kitchen scraps to inoculate all winter and then be heaped up into the compost pile come spring.

I took a deep dive into biochar production a few weeks back and what I discovered from the information available to me is that the most low tech solution, with the highest productivity and lowest environmental impact, was the use of an open head 55 gallon drum with a lid.
The supporting video for this technique is somewhere here on Permies, but suffice it to say that the trick here is to tilt the drum at a 45 degree angle.  Start with a small amount of material in the bottom and follow the rule of adding material as the material on the top begins to ashen.  Keep adding material in this fashion until the drum is full.  Then cap it off with the lid and let it cool.

No punching holes in the drum or lid.  Nothing.  That's it.

I have access to damaged hardwood pallets that have been heat treated, so they are very dry and ready to burn.  I suspect they will make for a nice biochar once crushed and innocculated.

Yup Thomas, we used that method on the lab in 2022 and it worked very well. So long as the lid isn't bent/warped it's very easy to finish the burn, and even if it is warped a bit you can just have some mud on standby to pack into any gaps around the lid. The next day everything was cool and the charcoal was very light and "clinky".

I don't remember if I got this from a permies video or a youtube video.
But, the taste test really does work.  A thoroughly cooked batch will have no taste at all.
It feels funny on my dental work, but, no taste.

Side note - you can really freak out somebody who doesn't know that there's nothing left but carbon.

Mark Brunnr wrote:David the Good referenced this video about using soup cans/ any cans with a crimping tool to make charcoal retorts in about 1 minute, which can then be tossed into any fire

I don't have much of a reason (nor room) to start larger fires where I am currently living, but for anyone else in a less rural location - these retorts also work excellently on a grill!

I used to use the grill to make biochar out of rib bones, ham bones, and other harder pieces of bone that are more difficult to compost - just by leaving them on the grill for a while - but I tried this method out today and I was very happy with my test.
I even threw a banana peel in there (the wavy thing in the middle of my photo), and it became beautiful biochar.

I have a second "worst case" test going at the moment, using some rotten pork and a few cherries - I know most of it will shrink down due to the high water content (and I'd prefer to compost those), but I'm curious to see if it will produce biochar rather than ashes or very burnt burnt nuggets of meat.

I've been using the can retorts with packed sawdust for a few weeks now and am still very happy with the results!  I've put a few pictures on here.  for comparison, it takes about 1-1/2 clear plastic containers of sawdust to pack into the cans.

That's pretty cool with the sawdust, Arliss! What is the average "cook time" to convert a can of sawdust to char?

Mike Farmer wrote:That's pretty cool with the sawdust, Arliss! What is the average "cook time" to convert a can of sawdust to char?

I'm not real sure.  i generally just put them in before i go to bed in the evening and the fire is out in the morning and i do it again the next evening.  Taking a guess at it based on the flames I've seen opening the door to look after putting them in (steel door without glass so i have to open it to see how the fire is doing), I would guess somewhere in the 2 hour range would be adequate.  I suppose there is a lot of variables in there but the way I burn that feels about right.