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New to biochar...

 
Posts: 97
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I've been reading about biochar and I saw a simple way to make and build a biochar kiln. It was 2 metal barrels, one was 30 gallon with 5- 1/2" holes drilled in the bottom of it (this was where you put the biochar material to be used. Then there was a 55 gallon barrel that the 30 gallon was put into. Once you filled the 30 gallon barrel you put the lid back on it and then filled the space between the 2 barrels with combustible material and it to had holes in it but was told the # of holes and size depends on material burned in the 55 gallon barrel. Depending on that material you may need more holes near bottom but not "ON THE BOTTOM" of the barrel like the 30 gallon, these side holes are where the air enters to allow the fire to burn. You also may need a few holes near the top of the 55 gallon barrel to properly burn, again depending on fuel used. The lid of the 55 gallon drum then has a smoke stack added (usually scrap metal or used stove pipe) Once you have the proper amounts of holes in the 55 gallon drum you can see that there will be little to no emissions coming from it (compared to open top) and there shouldn't be any smoke you can see. The way it worked was when the material between the 2 barrels burned it then caused the material in the smaller barrel to release combustible gasses that then also burned in the chamber and also helped making it work better. You can also use the top of the 55 gal. barrel to cook food as there is no emissions that can taint the food and it will help further reduce your need for other fuels to be used (ie stove, oven, grill etc.) Another thing I liked was after it was done there was ash in the 55 gallon barrel and only biochar in the smaller barrel. I can use the ash and biochar mixed into my composted chicken manure to help keep the nitrogen from leaching, the ash helps to make acidic soil more alkaline. So for me this is a good thing. I hope this gives some ideas for those interested in this and I'll post pictures as I start making my own "BIOCHAR KILN".
 
C Rogers
Posts: 97
Location: South Mississippi
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Here is an image I found on the design I was talking about ***EXCEPT I was told DO NOT put the grate OR holes in the very bottom of the 55 gallon drum. This is because as the gas is expelled from the 30 gallon drum the flames MAY go up and start the biochar on fire reducing it to ash... Thats not good. Also the holes in the bottom can allow hot coals to escape and cause problems. Except for that this image is the best visual of what I saw. As I said when I build mine I'll keep adding info and updates but for now hope this image helps (some say an image is worth a thousand words)

biochar-kiln-design-3.jpg
[Thumbnail for biochar-kiln-design-3.jpg]
 
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THis is a retort system and one of the most recommended styles to use.  As you can see looking through this forum, you will see that many different systems seem to be optimal for different situations. It's not what i use, but one advantage of this one seems that you don't need to turn it off.
John S
PDX OR
 
C Rogers
Posts: 97
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John Suavecito wrote:THis is a retort system and one of the most recommended styles to use.  As you can see looking through this forum, you will see that many different systems seem to be optimal for different situations. It's not what i use, but one advantage of this one seems that you don't need to turn it off.
John S
PDX OR



Yes John, I looked at a few systems and like you said, most others you have to "do things" like cover with dirt or douse with water while this one is just get the fire going and you can walk away... Once the fire is out its done, also what I like is the ash and biochar are each in a different container so you can use each when needed or sell/give away the part you don't want/need to others to help them with whatever they need (ash or biochar). Plus I'm then using things that around here would normally be added to scrap piles, or added to landfills. Instead I'm using them to cook, clear waste and debris from yard to make things that will help my farm and keep from throwing things out into landfills.
 
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If you are brand new to making biochar and you're not sure if you want to go through the time and expense of building a retort out of barrels and such, you can always make it the old fashioned way: a simple burn pit.

The key is to continually load wood on top of the existing fire in an even layer so that the coals below are slowly suffocated by the new unburned material on top.

Start with a stack of wood on the bottom of a shallow pit—2 feet is a nice depth, you can go deeper if you want.  I'll usually start with a bunch of messy branches left over after tree trimming.   Load enough wood that if spread out, it would cover the bottom at least 6 inches deep.  Once the fire is burning and the material is nicely burning, spread it out so that it covers the bottom of your pit evenly.  (I use a hard-tined rake for this).  Then load a layer of wood on top of those coals and burning sticks/boards.  Try to make that layer as even as possible.  I cut sticks down to a foot or two so that they fall flat onto the surface of the fire.  Boards work well, as they lay flat.

If you are burning big stuff like rounds from a tree or big hunks of wood, then try to pile up stuff that is a uniform size.  I have a bunch of "cookies" from a large ash tree that we cut down.  I'll break those down into smaller wedges about 6 inches across and throw them in there.  BIG fire with BIG chunks of wood.  Those will take an hour or so to begin bread down into coals.  If I throw small stuff on while waiting for those big chunks to burn, the small stuff will just burn away.

The key is to keep it burning hot and to make sure that every stick or board is fully burning before you add the next layer of wood.  I tend to add wood about every 10 minutes or so.  With the rake, I'll push the coals around and even it out before I throw the next layer of wood on.  And then as it's burning, you'll have a few minutes to cut up the materials for the next layer of fuel.  If you are burning thin stuff (branches a half inch or smaller) you may be tossing a new layer on every 3 minutes.

A second key is that you add materials that are all the same size.  Thus, if you are adding cut up 2 x 4's, throw them in at one time.  If you are adding smaller branches or tree trimmings, again, add similar sized materials so that you can gauge the burn rate.  If you added (for example) both 1 inch branches and 2x4's at the same time, by the time the boards were sufficiently charred, the branches would be completely burned away.  The rule: start with the thickest material FIRST, and then as you continue with your burn, add smaller and smaller burn stock until you finish with your thinnest branches.

Some people like to occasionally throw a layer of leaves to smother the coals below from time to time.  That's an option -- smothering it so that the coals don't completely burn away, but keeping enough of a fire burning so that additional materials continue to ignite as you add them.  I don't do this -- if you are careful about adding thick material first and then smaller stuff more frequently as the burn goes on, you'll be able to keep the fire from burning away all those precious coals.

I make this in my fire pit, which means that the air can only get to the fire from the top.  That aids in the smothering process -- the more I stack on top, the less the bottom coals are getting air.  You could get this same effect in a pit (as described above) or a 55-gal drum.  

Extinguish the fire with a hose when the top layer is sufficiently charred and broken down into coals.  Or you could dump a big pile of wet grass clippings or leaves to smother it.  Make sure it's completely out -- drown all the coals, or you'll smell smoke a day later and realize that all that lovely charcoal you made has been smoldering away and burning off.

One of the advantages of the pit method is that once the fire is out, I put on an old pair of work boots and stomp around in there, breaking it into smaller pieces.  Or I'll use a shovel and chop, chop, chop it to break up the big chunks.

If you use the pit method, you could go ahead and build a compost pile right on top of it.  Use a fork to turn the compost and at the same time, begin to integrate the charcoal into the compost, thus making it biochar.

Best of luck.

m
 
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John Suavecito wrote:As you can see looking through this forum, you will see that many different systems seem to be optimal for different situations.



Indeed.  I have used the TLUD, retort, and pit (trench) methods.  Each has it's advantages and disadvantages.  The pit method is my least favorite, but that may be simply because I need more practice with it, and at my new place I currently don't have ready access to water.  I want very much for it to become my method of choice, for two reasons.  1)  You can make very large amounts at one time, and 2)  I dislike having ugly, rusty barrels sitting around, especially in my food forest where they are currently being used.  The water issue will be corrected by spring so I hope to revisit that method.  Currently, I use the retort method most often for exactly the reason given.  It's pretty much a fire-up and walk-away method.  Come back the next day and you have charcoal.  I rarely do that because I like making charcoal and playing with fire, and sometimes you have to add more wood to completely char the wood in the barrel, but it is convenient that you don't have to babysit it.  I find, for me, the retort also makes the best charcoal.  It's very easy to tell when it is done, as opposed to the other where you often get brands.  The TLUD  is similar in some ways, but at the end of the burn, you need to seal the top and cover the bottom vents, so at the very least, you have to be there at the beginning and end of the burn.  It's harder to tell when the charcoal is finished.  That is also a problem for me with the pit method.  Currently, I haven't used the pit enough times to find the line between being sure the charcoal is finished, and burning too much of it to ash.  The pit method doesn't realistically give you a choice except to quench.  Much of it comes down to situation and personal preference.  The good news is, there isn't a wrong answer, all work.

Cross posted with Marco.  Nothing I said is a reflection on his post, as I hadn't read it when I posted.
 
C Rogers
Posts: 97
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Thanks Marco and Trace...

I personally like the TLUD method best not only for the walk away part but also because I get 18-22 tons of composted breeder house chicken manure once to twice a year and spread that with my pull type manure spreader. I was planning on adding the ash and biochar directly into the manure spreader as I spread this. My spreader when I go under 5MPH only spreads the litter 4-5 ft wide aprox. 1-2 inches thick. I have 4 ft wide beds so this is perfect for me and will raise my pH (breeder houses add limestone for grit for the chickens and oyster shell to the feed for egg production, along with the ash this should actually raise my pH to get it closer to 6.5-7 pH) the biochar added to the manure (at least I hope) will help keep the nitrogen from turning to gas and evaporating. Here in south Mississippi the temp and humidity are high so Nitrogen is turned to gas quite readily. I need to play with how much ash and biochar will be needed per load on the spreader. It holds (depending on moisture) 1/2-3/4 ton of manure. I usually put about 6-8 tons per acre. I am intensive farming BTW, thats why this isn't overkill like some may think. I have graphs showing how much ash to add to raise pH 1 point but I've never seen how much biochar to add per ton of compost etc... Any tips on that??? And am I correct in thinking this will help hold some/most of the nutrients till the plants "NEED" them, as I've heard too much biochar can actually lower your "available" nutrients and lower plant production IF NOT DONE RIGHT.
 
Trace Oswald
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C Rogers wrote:Thanks Marco and Trace...

I personally like the TLUD method best not only for the walk away part but also because I get 18-22 tons of composted breeder house chicken manure once to twice a year and spread that with my pull type manure spreader. I was planning on adding the ash and biochar directly into the manure spreader as I spread this. My spreader when I go under 5MPH only spreads the litter 4-5 ft wide aprox. 1-2 inches thick. I have 4 ft wide beds so this is perfect for me and will raise my pH (breeder houses add limestone for grit for the chickens and oyster shell to the feed for egg production, along with the ash this should actually raise my pH to get it closer to 6.5-7 pH) the biochar added to the manure (at least I hope) will help keep the nitrogen from turning to gas and evaporating. Here in south Mississippi the temp and humidity are high so Nitrogen is turned to gas quite readily. I need to play with how much ash and biochar will be needed per load on the spreader. It holds (depending on moisture) 1/2-3/4 ton of manure. I usually put about 6-8 tons per acre. I am intensive farming BTW, thats why this isn't overkill like some may think. I have graphs showing how much ash to add to raise pH 1 point but I've never seen how much biochar to add per ton of compost etc... Any tips on that??? And am I correct in thinking this will help hold some/most of the nutrients till the plants "NEED" them, as I've heard too much biochar can actually lower your "available" nutrients and lower plant production IF NOT DONE RIGHT.



Everything I have read says that charcoal will lower your production for possibly a year if not inoculated before being used.  You are working on a much larger scale than I am.  I have no idea how to make charcoal in the amounts you are going to need.  Most people recommend charcoal be added at 20% or so, but more testing is in order, with some things doing well at less and some at more.  Adding charcoal to your chicken bedding in large enough amounts should hold a lot of the nutrients that would otherwise be lost.

 
C Rogers
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Trace Oswald wrote:

C Rogers wrote:Thanks Trace...

I've never seen how much biochar to add per ton of compost etc... Any tips on that??? And am I correct in thinking this will help hold some/most of the nutrients till the plants "NEED" them, as I've heard too much biochar can actually lower your "available" nutrients and lower plant production IF NOT DONE RIGHT.



Everything I have read says that charcoal will lower your production for possibly a year if not inoculated before being used.  You are working on a much larger scale than I am.  I have no idea how to make charcoal in the amounts you are going to need.  Most people recommend charcoal be added at 20% or so, but more testing is in order, with some things doing well at less and some at more.  Adding charcoal to your chicken bedding in large enough amounts should hold a lot of the nutrients that would otherwise be lost.



WOW, ok I'm way off on my thinking of how much to add then, I'll probably be adding just a 100-300 pounds per ton of manure so it shouldn't reduce my crops, but also will not be able to maximize the holding of nutrients either :( but it should help some. It also will be a continual thing just like me adding manure to beds so eventually it should continually add to my soil. Also at least in my head I'm thinking that by adding the biochar at the same time with the manure it should inoculate the biochar and reduce/eliminate the lowering of production (at least thats what I have heard is that if added to compost instead of just adding to soil it then has been inoculated with nutrients from said compost). Also except for Nitrogen, every soil test I've had in my crop fields showed high to very high of every nutrient. My calcium is even ok BUT pH was 5.5-6.7 pH (depending on which field). My calcium is about the same but pH was different (strange to me but ok) so I added lime where needed and am trying to add nutrients as needed for intensive farming, and just to keep maximum nutrients available for my crops.
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