I get the basics of the process and have had 2 semi successful runs. I used a 4.5 gallon metal oil can inside a 55G Drum.. I loaded the smaller can and put it in the bottom of the drum standing on the flat cylinder end. I only cut a vent in the bottom side of the Drum so that things would burn and get the heat up enough to cook the wood in the perforated smaller can. I get it roaring hot and keep it that way for an hour then lid the can and cover the vent to keep from smoking as air is reduced. I get a 4.5 G can full of almost perfect biochar (bottom layer or large pieces were not complete) but a lot of the pieces sound like glass chimes when you go through them with your hand. the 55G burn chamber yields wood ash and biochar as well as unburnt wood. I see that a top down burn process is used to better consume gases. I haven't seen a simple 55G drum retort design that I feel confident in. I am interested on making a simple and more effective version of what I am using now. One thing I know would improve mine is just the addition of a second vent opposite the one I have now in the burnchamber. Smoking in my burns isn't bad as I am generally experienced at building fires. I've seen various pipe configurations which I guess are bringing air into the burn chamber..?. I've looked at J rocket configs... anyway, I've looked at a bunch of these and would like to home in on one..
So the questions I have:
1. Has anyone seen a good/efficient design with minimal components?
2 Does an inner/outer barrel make the simplest effective chamber or is some other config such as stacked work well?
3 for inner biochar chamber such as mine, is there a noted optimal volume? I'm using 4.5G
4. How much difference does burying the thing make?
5. What are the pipes doing on these things supplying air or exhausting ?
We've done several runs using a 30 gallon barrel as the retort inside a 55 gallon one. A 4.5 gallon one seems really small to me. Our setup has 4 air holes around the bottom of the 55 gallon barrel, each maybe 4 square inches. The 30 gallon barrel has no holes, just the one end open. We have a lid for the 55 gallon barrel that has a hole on top and an attached 6" stove pipe about 5 feet long. There's only about an inch between the barrels to stick the burn wood in, but it seems to be enough.
The 30 gallon barrel is flush with the bottom of the 55 gallon, so in order for the gas to escape it has to expand until it forces the barrel up. One time it actually popped - it sounded like a small explosion.
We use a fire muffin (a small paper cup filled with wax and sawdust) to start the fire. Wood is stuffed between the barrels and on top of the 30 gallon to just where we can still get the 55 gallon's top on. Light the fire muffin, wait a couple minutes to make sure it takes, put the lid on. The whole burn is done in an hour.
I even made a jig to help keep the barrels in place when they are turned over. We don't bury it. Its really pretty simple and has worked every time except once when the burn wood was wet. We don't use any pipes except the chimney. We do burn from the top down. We know its working well when we can see the flames just make it out the top of the chimney.
Creator of Shire Silver, a precious metals based currency. I work on a permaculture farm. Old nerd. Father.
It's hard to wrap my head around a 30G inside of a 55G giving a complete burn.. But the design is clear. I reckon the strong pull effect starting in the base of the 55G's 4 vents and going out the 5 ft top exhaust is raising the temp very fast and to very high temps compared to my experimental test retort. I've already observed that I get cold spots opposite the single vent in my burn chamber which I knew I had to fix... luckily I have an approx 30G kerosene tank which I was planning to use for this purpose, I just figured when I started that it would not carbonize inside... but if you are doing it, then it seems that it is just my "velocity" that seems lacking. I'll get on it thanks!
4.5 gallon inside a 55 gallon also seems small to me. I am currently reading ALbert Bates book on BIochar and I took one class. I love how you are sharing your ideas so more people will experiment with these processes. Bates says optimally, we get 80% biochar out of the original organic material. He emphasizes that you don't need to have the biochar in the inner container, it can be in the outer container. I am planning on figuring out how to make this practical so we can have a lot more people doing this.
Thanks for the applause! In my case I had a a lot of clean enough debris (read as not too toxic with paints etc) to use as burnable fuel. in fact I had too much and after moving things around a couple of times I realized why the old guys back in Jersey just burned that stuff off instead of trying to utilize it as an energy source. But I've lived in huts in South America and other very simple off the grid situations and I hate wasting stuff if I can avoid it. Put that together with my love and skill of cooking with wood/charcoal fire. I'm trying to make what they call in Japan binchotan - which just means "really damn good charcoal" vs. Sumi which is most other grades. Binchotan is expensive as it is made of high density wood types. The soil in our farming area is also poor in quality... SO how many turkeys can you shoot with the same pile of junk the previous owners of the house left us? In the process of rebuilding this 100 year old farm house and realizing how irritating moving this stuff or wasting it would be, I built a retort as well as a burn barrel to make ash for the field.
With my retort I use the inner barrel so far to work on the binchotan and the outer burn area produces a mix of biochar and wood ash.... I am going to test the upgrade mentioned above and see how that flies as I plan on opening a cafe and will need high quality product to cook with.
I think the biggest points that get me down to doing these things are 1. See that Everything is energy in some form. 2. Love of experiment. (Experiment is just the adult evolution of Playing and teaches more in an hour than a month in a classroom. 3. Don't try to get it perfect on the first try ( or you'll never get your nose out of the intellectual end of things which is meaningless without results.) I mention these in response to your comments on encouraging people to do things, I think developing that kind of outlook is one way to spur action. (I am not meaning to discourage classes or study, just to take the step of manifesting as well)
And in a few experiments I went from 30% success to about 90% in my last run and now I have a good set of tried working principles and it was fun.
Hi Brendan, I am curious why the closed retort? I have used one for making gasifier fuel but not biochar. Seems like overkill. New here and don't want to step on toes. Have you looked up Gary Gilmore's two barrel system for making charcoal? Basically a 55 gallon drum full of material, holes on the bottom burned down and sealed. A second hollow barrel on top as an afterburner. No inner retort lots more material per load, great biochar.
Best regards David Baillie
I'm taking a look at the guy you mention. Maybe I can test it out when I have time as my main concern right now is indoor heat. But as far as ease of construction, what I have is very simple and a lot of people with plenty of experience use a similar retort.. It's just one can in another with some venting and a top exhaust to help draw... K I checked some vids by Gilmore, yea obviously he's Old Pro. Still though, with the one I'm using I can Start it and never need to look at it. I come back next day and its finished. His has no automatic stop that I can see. He has an open top with a single chamber, how is that preferable? Mine would not gasify effectively it's too many gaps I think. Also for Binchotan, quality charcoal I will have to control temperature change more effectively and this is where I want to end up later. (I don't have that ability yet)
Hi Brendan, if you look at yahoo groups the charcoal gasifier group you will find all sorts of charcoal makers. If you like the sealed retort I made 20 gallons or so last winter in my wood stove with a length of 7" stovepipe and two end caps. It made the best hardwood charcoal I have made. You could immerse it while still hot to give you that desired consistency. I never do as my goal is always motor fuel. Some people on the group do.
Best regards David Baillie
This system that I built is based on a design from a guy in Holland. The website that I have has a basic step by step (with photos) process to understand the build. The system that you describe (as other's have mentioned) seems like overkill on the volume of the burn area in comparison to the volume of the char area. A larger inner barrel is what you want. The system I have is not ideal, but it works. I would like a slightly larger inner barrel, but it would make loading my most available fuel more difficult, so I have, unfortunately less char than I would with a larger inner barrel as he has in this description.
"Never doubt that a small group of thoughtful, committed citizens can change the world; indeed, it's the only thing that ever has."-Margaret Mead "The only thing worse than being blind, is having sight but no vision."-Helen Keller