Terra Preta - The parent thread which started it all

[Taildragerdriver]

David:

Thanks for the input. I have seen several 55 gallon drum methods. I was kind of thinking that the burn it inside method would be the best also. I'm glad to have somebody else confirm that. That is what I will try initially.

As far as your suggestion about using lots of drums. I'm not sure that would be practical to produce the large amounts of charcoal needed to do a farming scale test it would take a long time. The wigwam burner is about 150 feet in diameter so I can make a big dense stack of wood and burn it in the middle covering it with earth using my backhoe before I start it. I can drive into the wigwam burner and use the backhoe to work and not do it all by hand. I'm pretty sure if I started it first and them piled on the wood that I could not control it.

My best guess is that I probably need 5 or 10 tons to do an acre. Not something you do a drum at a time I don't think. I could be wrong.

I hope to get a chance to try something soon and I will report back on my results.

Thanks for the ideas.

Taildragerdriver

[davidgmills]

Taildragerdriver: 5-10 tons per acre. Wow. More power to you. I have been thinking if we could get every human to have a goal to put one ton of charcoal back into the earth before they die that would be a laudable goal. Six billion tons of charcoal in the ground would do wonders for the planet.

At this rate you could single handedly save the planet for us all.

150 feet in diameter. That is a big fire ring. I really cannot imagine what his thing looks like, but you will put us all to shame.

As far as the 55 gallon drum method, there is a blacksmith that has a good website that shows how he makes charcoal for his forge. Very interesting method in that he builds a fire under the drums and then seals the drums and reroutes the gases from the heated drums back into the fire. After a while the gases are the fuel that keeps the process going. The only problem with it seemed to me that his method, even with using the gases, still used more wood for fuel than charcoal. If you use half the wood for fuel and half for charcoal that seemed very wasteful. My process probably did not involve using 1/10 of the wood as starter fuel.

In order to get urban areas to make charcoal, I have thought about making a pit that barbecues with it. (Memphis is considered the barbecue capital of the nation,it has a few rivals but we really don't pay them much attention). So if you could make a pit that made barbecue you would not incur the wrath of the neighbors. Most people do not complain about the smell of barbecue. They don't have the same sentiments about smoke.

And making charcoal is smoky.

One other thing to keep in mind as far as tonnage. The wood shrinks in size when you charcoal it down to about 1/4 to 1/3 the size, but the shrinkage in weight is much greater than that. After all the water and gases are burned off, charcoal may only weigh an 1/8 (just guessing here) or so of its original weight. It is every light.

Erich: I had read your posts elsewhere that Missouri is the capital of charcoal making in America. Unfortunately, on an suburban plot (about 1/3 acre), I can not feasibly even use a ton much less 125 tons.

But I am also trying to find ways small plot owners can take their annual dead wood and clippings and charcoal them rather than send them off to the local landfill. That means coming up with a way to do it on a small scale and a way to do it so that neighbors don't complain. That is why I like the barbecue pit idea. I am thinking about taking a garbage can and making charcoal in it and putting a grill at the very top of the heap. Barbecue is not supposed to be cooked directly under a flame anyway. It is supposed to be cooked by indirect heat. I could do that and make charcoal at the same time.

As far as buying it though, at least for now, for us urbanites and suburbanites, I am afraid we are doomed to buy BBQ charcoal for now. Heck, I could not even find a place that had lump charcoal. I had to buy briquettes. Walmart sells lump. But they were out. And I am sure it will be considerably more expensive. But I want to try lump if I can find it.

[erich]

David:I think the figure is that Charcoal is 30% of the dry weight of feedstock.


$125 dollars per ton,
I thought , you could fill a pickup truck with 1/2 a ton for $62.50

Trail:

That structure sounds like you have a permanent replacement for the dirt in charcoal mound building.

[davidgmills]

Erich: You are the guru, so I will not contest what you say. But upon really thinking about it some more, I probably was low and what you say seems much nearer to what I observed. I never weighed anything so I was guessing.

I think it seemed lower because it crumbles so easily and probably I was not picking up the entire pieces of the stock I had started with.

But if he is going to be moving charcoal any distance from where he makes it, he is going to lose a fair amount if it crumbles as easily as mine did. This would be especially true if he makes his charcoal in earthen pits and smothers it with dirt.

Unfortunately, I don't own a pick up truck. I need one so seldom, I can not justify owning one.

[erich]

WOW.............This is the first I've seen of a process like Dr. Danny Day's on the market:

BEST Pyrolysis, Inc. | Slow Pyrolysis - Biomass - Clean Energy - Renewable Energy - Char - green coal - pelletized fuel - syngas for electrical generation - carbon credits - increases rural jobs and construction development

[Michaelangelica]

Originally Posted by Taildragerdriver

Of course for my needs this won't make a dent. So for a larger scale I have access to an old "wigwam burner" left over from the old lumber mill near my pastures. I plan to start with the a traditional mound burn as described in the following site.

Chapter 6 - Making charcoal in earth mounds

This looks interesting; but look up "Coppicing" used to produce charcoal in England, sustainably, for the last 1-2,000 years. There is a link in this thread or google it. It may help you when you start your own mound

[davidgmills]

Erich:

According to Best Pyrolysis' website:

"Approximately 35% by weight of the dry feed material is converted to a high-carbon char material that is collected on the discharge of the kiln."

[Cedars]

Originally Posted by davidgmills

As far as the 55 gallon drum method, there is a blacksmith that has a good website that shows how he makes charcoal for his forge. Very interesting method in that he builds a fire under the drums and then seals the drums and reroutes the gases from the heated drums back into the fire. After a while the gases are the fuel that keeps the process going. The only problem with it seemed to me that his method, even with using the gases, still used more wood for fuel than charcoal.

Is this the website?

Making Charcoal

I think part of the high wood consumption was that his unit wasnt permanent. Lots of heat loss via that alone.

[davidgmills]

Cedars:

Yes that is the website.

And of course he probably was not interested in devising an efficient method of making charcoal because he probably does not have to.

But I remember him commenting that he used about as much wood for the starter fire as he did for the charcoal stock in the drums.

In terms of efficiency, I am sure that ceramics would be a lot better than metal. I have thought about getting a soapstone stove for some time now because soapstone is so very efficient at retaining heat.

I have also thought about making a permanent charcoal/barbecue pit out of fire brick and brick for the same reason, but since I am not a mason, I don't know how good I would be at it.

Onething that intrigues me about th Best Pyrolysis website is that they are using grases and shrubby materials as stock as well as wood. For the suburbanite and urbanite, the ability to use grass and leaves as stock would certainly help the landfill problems.

[Taildragerdriver]

Lots of good Information.

The first problem is making the charcoal. I am glad to know about the extimate of around 30 to 35% by weight so that means I will need 3 tons of wood for each ton of carcoal I'll get out.

Cedar: That is one of the websites I found. I found another that shows how to do it by starting a fire in the bottom a drum.

Making your own charcoal


This one looks pretty simple and is what I plan to start my tests with. I think this mimics more closely what I will have to do with the dirt mound. I probably will modify the method a bit so I can get practice starting it already filled with wood from a hole in the side I can close off.

David:

I'll try and take a picture of the Wigwam burner this weekend and file it on the site for all of you to see. The 150' is an estimate. I'll actually measure it too. It would be useful to know.

At least intially I will build a fire in the middle about 50' in diameter and drive around it with the backhoe to cover it with dirt.

I hope the smoke is not an issue for me. Lots of people burn around here and there are not any houses real near the burner. If I do it right it is mostly supposed to be steam. I'm also interested in the air polution aspects of making charcoal. Not a big issue where I am with the locals but it would be good to know for all kinds of reasons.

Also about your comment of how far I have to move it. I would load it into the manure spreader with the backhoe and then pull that with my tractor. The pasture is about 1/2 mile from the burner. I probably would only do this on calm days. Hopefully there wouldn't be much loss in the process. For any of you who may not be familiar with tractors, they don't go very fast, so I don't think the movement would cause it to blow out of the spreader till I start turning the spreader on.

Questions for you all

How much charcoal do I really need?

The next question I have is about my calcualtions and some of you gardners with experience might be able to help me with this.

The reading I have done indicates that the optimum charcoal in the top soil is actually about 40% by volume. So my calcualtions go like this: the first foot of an acre is 43,560 cubic feet. So 40% is 17,425 cubic feet of charcoal. I'm kind of guessing dry carcoal weighs about a pound/ cubic foot. That would require 8.7 tons per acre. I want to test that weight estimate with the small drum made charcoal soon.

The pasture land I am thinking of testing this on has not been cultivated since some time in the 1950's and I am shooting for a single till treatment here to get it back into production. On pature land I usually work it up and replant every 20 years or so. Therefore I want to go for the optimum the first shot.

Also I live in a pretty dry place. Most of the moisture comes in the form of snow equivilent to about 12" percipitation a year. I'm concerned about wind errosion because I think charcoal in topsoil could blow away pretty easily if used in row crop type situations. That is why I'm thinking of using it in pasture initially. Once it is put in and the cover is reestablished the alfalfa/grass should hold it in place.

OK so the question is can anybody confirm this idea of 40% by volume or is that too much or too little?

Are my weight estimates close?

The wood I plan to start with is hardwood, aspen, cottonwood, and willow. But the majority of the wood available around here is softwood pine, douglas fir and true fir.

Should I try to get one or the other or will both work fine?

I would like to hear from people that have used both in a terra preta soil situation as to the beneifts of each. I have read that if you have soil ph issues the hardwood is better.

Thanks.

Taildragerdriver