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Here is a list of char-making references, organised by type of design. The list combines previous links from this thread with other research. The list is restricted to items that convey at least some idea of the actual method / equipment used. Hopefully readers can judge the approach they could most easily adopt.
I suggest everyone do it at least once or twice as it is very safe IF YOU DO NOT MAKE IT IN YOUR HOUSE!
YOU MUST MAKE IT OUTDOORS. YES YOU WILL POLLUTE THE NEIGHBORHOOD WITH YOUR SMOKE, SO BEWARE, BUT NO MORESO THAN IF YOU WERE BARBECUING. The smoke just won't have the aroma of a barbecue. It will smell like smoke.
The principle is very simple. You are going to roast the wood just like you would roast a chicken. You do not want the wood to catch on fire anymore than you would want your chicken to catch on fire.
Roasting the wood drives off three things, in order of lowest temperature: water, gases, oils. The water, gases, and oils are what we call smoke.
When the water is burning off at the beginning of the process, the smoke will look gray or white. When the gases burn off near the middle of the process, the smoke begins to yellow. When the oils burn off towards the end of the process, the smoke turns blue. When it quits smoking altogether, you have charcoal!
Here is the most efficient method I found for urban use. I started with a small popcorn can about 2 and 1/2 gallons. It must have a lid. A galvanized trash can with a lid would be great, but I could not find one to buy. So would a 55 gallon drum with a lid.
In the bottom of the can start a small raging fire. Once the fire is going good, put in just enough lump sized pieces of wood to extinguish the flames but still leave the wood smoldering. From here on out you will be roasting the wood, not burning it. Branches 1 to 2 inches in diameter and cut to 3 inches or so in length are perfect to make "lump" charcoal. Slowly fill up the can with the "lumps" of wood keeping the wood smoldering at all times. Once the can is filled up, loosely put on the lid, leaving a crack between the lid and the sides of the can (usually about 1/2 to 1 inch) to let the smoke out. DO NOT LET THE WOOD IGNITE. The lid is necessary to keep the wood oxygen starved so that it smokes not ignites. REMEMBER YOU WANT TO ROAST THE WOOD, NOT BURN IT!
When you are done, if the lump charcoal tinkles like a wind chime, you have made it right. If not, you probably didn't cook it long enough, or overcooked it.
The process, which seems to waste the least amount of stock, takes a coupe of hours depending upon how much stock you begin with. When the process quits smoking, you have charcoal. Put on the lid tightly and extinguish the fire. About 1/3 of the stock you started with will be charcoal.
Once the process is complete and the charcoal lumps are completly extinguished, pulverize the lumps (I use a pair of pliers) and put the charcoal particles in your garden. Mix thoroughly with the soil.
The first year, you must kick start the terra preta process with fertilizers, because the charcoal has not yet had the ability to filter out of the air or rain water, any nutrients for the plants and bacteria. The bacteria which thrive in the charcoal have a symbiotic relationship with the root hairs of plants and they are constantly taking the nutrients captured by the charcoal to the plant roots.
You are done. Welcome to the new world of terra preta.
Now feel very good about yourself!
Oh, and feel free to make a claim for some of Al Gore's and Richard Branson's prize money. You have earned it.
Has it simply been taken from a living carbon sink?
True that. From a recalcitrance perspective, converting a living carbon sink to a charcoal sink is a good thing only if that charcoal ends up in the soil (versus under the BBQ). A net increase in soil charcoal levels world wide is more effective at global cooling than the same net increase in lignin because charcoal is more recalcitrant.
From a carbon sink dynamics perspective, converting a living carbon sink to a soil charcoal sink is a good thing. The living carbon sink functions to convert atmospheric CO2 to carbohydrates. Stimulating this rate capacity is fundamental to the attraction of biochar/agrichar utilization.
I find these two perspectives compelling but am concerned that it doesn't account for the relative impact on climate change of the differences in N20, CH4 and CO2 generated from the lignin breakdown versus pyrolysis: charcoal production can produce high levels of N2O under some, but not all, scenarios. N2O is potent greenhouse gas. Any scheme to produce agrichar should address the N2O production involved. High nitrogen content biomass increases N2O, as does lowering the temperature of pyrolysis. I expect (need to know more) that utilizing the wood gas for fuel can eliminate the N2O load to the atmosphere. How we make the biochar and what we do with the biogas are both as important as what we do with the biochar.
Note: the solar charcoal production mentioned earlier in this thread seems to produce CH4, but did not mention N2O. I would like more information in that regard.
created by the pyrolysis process is the real challenge.
Unfortunately, since I am a lawyer not a scientist, I can't help much with the design. But I had envisioned a ceramic based stove, potentially made out of pottery for third world applications. Even better would be a stove made out of something like soapstone for first world applications.
Modern wood stoves burn exceptionally clean, combusting the gas with catalytic converters or secondary chambers that get intensely hot.
I have kind of envisioned a three chambered stove/barbecue/smoker. The first chamber would have a small amount of sacrificial starter woodstock. The second chamber would contain woodstock for charcoal and the third chamber would be an oven for cooking/barbecuing/smoking. Obviously, the gases produced in the second chamber need to be redirected into the first chamber where they ignite and keep the oven going. Maybe catalytics are necessary here -- maybe not.
But that is what I have envisioned.
If they can make woodburning stoves that recombust all the gases, why not take this technology and use it for making charcoal in our homes?
After all, heating and cooling our homes takes up about 60% of our energy requirements, depending upon location.
created by the pyrolysis process is the real challenge.
I would love to be BBQing on an inverted downdraft gasifier. A BBQ retrofitted to make charcoal instead of burning it would be a kick. I'm looking fo a Weber Smoky Joe 14.5 inch....
This is a good article on charcoal in Horticulture
You may want to go to the original for the references. I have edited them out.
Has anyone used charcoal for propagation? or know of any research on the subject? It may stop 'damping off" and promote germination of some plants. Does anyone know anything about this? M F C F
Charcoal is much more widely used and available in the horticulture industry in the UK than here in Australia. They still coppice some forests. The English are also taking a new look at charcoal to replace water holding polymers, perlite and vermiculite.
Quote:
Horticulture
Charcoal has been used for horticultural purposes for at least two thousand years,
Archaeological research has come up with evidence of charcoal being used as a soil
ameliorator in the Amazon basin around the time of Christ. (Do a web search for "Terra preta" for more information-Michael)
Green keepers of golf and bowling clubs used charcoal extensively as a top dressing but in recent years this has been substituted by sharp sand, the reason may have been that the demise of the British charcoal industry caused a shortage in supplies of the correct grades. Fine charcoal powder used on lawns (golf) absorbs and eliminates excess amounts of fertilizer and chemicals present in the soil
Charcoal was widely available from horticultural sundries men up until the late 1960's,
for use mainly in bulb fibre where the pots do not have drainage holes. The charcoal was
said to keep the compost 'sweet'.
Orchid growing employs the use of charcoal and specialist growers of carnations and pinks find charcoal to be invaluable.
It has been reported that charcoal may act as a means of eradicating moss in lawns.
Trials have been carried out and the results are currently being analyzed
Research has shown that growing mediums that have charcoal present, are able to buffer the effects of sporadic watering, by reducing the frequency of watering whilst helping to prevent 'damping off'
Charcoal also reduces the leaching of fertiliser in free draining soils as the charcoal's porous carbon structure enables the nutrients to be held for slower release to the plants
.
The inclusion of charcoal in open seedbeds showed that it facilitates the uptake of nutrients. Calcium uptake almost doubles, with significant increases in potassium, magnesium and phosphorus, the pH increases slightly and there is an obvious increase in organic matter.
Charcoal has been recommended as part of the treatment for the eradication of a fungal disease, Cylindrocladium that infects Box hedges.
Charcoal has proved to be an ideal renewable substitute for perlite and vermiculite, compost additives used to increase aeration and aid drainage, but both finite resources.
They reported that the main reason for the decline in the use of horticultural charcoal was that it is a dirty material to handle. If uses can be found that have clear horticultural benefits and minimum handling, then we believe that a considerable market exists. For example, charcoal would make a good additive to grow bags, where the contents aren't handled much and there are problems with erratic watering.
The currently favoured water retaining gels are not liked by all growers and there are doubts about how well they actually release the water they have absorbed "Petunias in hanging baskets tested in greenhouses showed no benefits when water-absorbing polymers were used. And plants grown in media containing water-absorbing polymers required watering just as often as plants grown in potting soil containing no water-absorbing polymers.
Also, their usable life is limited by the amounts of salt or fertilizers in the soil
". Hence, charcoal could be used where watering may be a problem, e.g.
hanging baskets, or where it is hard to change the compost, e.g. in large tubs.
Charcoal could be incorporated into locally produced 'green compost'. No further
processing, other than simply grading would be required and transport costs would below. We have had preliminary discussions with Scarborough Borough Council about adding fines to their Green Compost and they hope to do some simple trials in hanging baskets.
__________________ “God does not play dice with the universe; He plays an ineffable game of His own devising, which might be compared, from the perspective of the players, (ie everybody), to being involved in an obscure and complex version of poker in a pitch-dark room, with blank cards, for infinite stakes, with a Dealer who won't tell you the rules, and who smiles all the time.”
Gaiman & Prattchet.
To Malcomf, You have a very good point on how Terra Preta was made. I have inclosed a set of notes (first draft) that I will be using in a talk on March 15 to a combination of the local Sierra Club and and as many garden clubs as we can get to come. This is the introduction part. I will also show how to make charcoal at home and finish with the carbon sequestration piece.
I am trying to char up my kitchen wates and am going to char (if possible), cow and horse manure, and pine needles both dried and fresh. I am working on a way to make some of my char with a lower ph and that is why I will try the pine needles. All this is experimental and for every sucess I have I also have something that ends up like....(cow and horse manure).
RB
Charcoal as a soil amendment: The Terra Preta effect.
Between 400 and 1500 years ago the Indians of the Amazonian basin created a type of soil that we now call Terra Preta de Indio or Black Earth. These soils are characterized by their high charcoal/carbon content, increased level of soil organic matter, resistance to nutrient leaching, and high fertility for plant/crop growth. The one factor in common that all Terra Preta soils have is a high level of charcoal (up to 40%), and it is the physical/chemical properties of the carbon in the charcoal that are responsible for Terra Preta's unique structure.
Carbon has the ability to make long chain molecules, adsorb onto its surface both solid and gaseous compounds, and is resistant to environmental decay. When carbon is in the form of charcoal it also retains moisture, makes an environment for microbial life, and improves soil texture. Carbon is the bases for all life and there are more carbon compounds than all the other elements combined. In soil carbon exists in unstable easy to use and recyclable forms in microbes and soil organic matter, and highly resistant stable forms in charcoal. Through the process of weathering and oxidation stable charcoal/carbon will eventually break down into labile forms but this process depends on many environmental factors that differ between soils due to their microbial makeup, parent material, and physical structure of the charcoal/carbon. Not all charcoal is the same as its charring temperatures (350 to 900 degrees), and its parent stock (woody versus non-woody material), give differing types of charcoal/carbon unique properties and nutrients when added to soil.
There is extensive debate in how the Amazonian Indians created Terra Preta soils as their cultures did not survive the initial meeting with European explorers so we have no first hand knowledge of the process. What can be inferred is that these people used their garbage and latrine wastes to provide organic matter that along with charcoal/carbons unique properties created Terra Preta soils. We don’t know that exact process but in a hot humid environment garbage and latrine wastes would start to smell, attract bugs and animals, and be a source of disease. The Amazonian people most likely found that adding ash and charcoal or periodically burning the top of the garbage/latrine piles would get rid of the smell, alleviate the bugs/animals, and minimize disease. The addition of charcoal in one way or another to their wastes was a hygienic practice that Amazonian Indians engaged in to keep their villages clean and healthy.
What the Indians also found was that the combination of organic matter/charcoal created fertile mix that when added to the nutrient poor soils of the region made them much more productive. In essence they made compost with the unique feature of a very high charcoal/carbon content that gave the soil greater nutrient/water retention while modifying the soil texture for better drainage and aeration.
To create Terra Preta type of soils what is needed is to replicate the practices of the Amazonian Indians. The first is to create charcoal with many unique properties based on charring temperatures, what material is charred, and whether the material is totally charred or partially charred. This was not a process that was exact for the Amazonians nor should it be today as the variability and variety of the charcoal is what provides both stable and unstable carbon and wide range of nutrients in many different forms and compounds. The second factor is what material did the Amazonians char and the anthropological evidence is that they charred or partially charred everything, plants, dead animal, village debris, garbage, their own latrine wastes, and the remains of their most important source of protein, fish.
Village sites and Terra Preta areas most often occur on bluffs near rivers which provided the Amazonians both their major source of protein and their major source of transportation. Even though their Terra Preta areas were still productive if the course of the river changed then the villages would relocate to be close to fishing areas and their transportation source, the river. What the large amount of fish in their diet provides for Terra Preta soils is a source of calcium and phosphorous that ended up in their garbage/latrine areas and then into their soil and back into the plants that they grew. In replicating Terra Preta soils there needs to be a source of calcium and phosphorous added to insure that the conditions and materials that originally created these soils are duplicated today.
I have been busy this last 2-3 weeks and finally caught up (but not yet digested), all the posts in the last 10 pages. The quality of the posts and the science behind them is fantastic!!! I am sure that Johannes and Bruno are reading (or having a grad student read), this site, and our ideas, after being suitably massaged, will show up in research and papers. They belong to the "publish or perish" world while we do the grunt work and actually get our hands black. (Do you think either of them have a set of "charcoal making" clothes that sit in the work room smelling of campfire?). Of course we wouldn't be where we are without their papers, research, and efforts so I applaud the efforts and they can have some of my ideas (citations please!).
Special kudos to Malcolmf for the recent excellent posts and always to Michaelangelica (that’s a "girl's name isn't it? Excellent post that one!), who is like the glomalin of this site.
Some replies to everyone’s recent work:
To davidgmills, the charcoal cruncher works well on pure charcoal but when I used it on partial biochar it is still not sturdy enough. What I am trying to do on one of my project is take a solid clay soil and add charcoal and SOM to amend the texture of the soil. I am after larger pieces of char and want some of the still wood part and the interface between the charcoal and the wood. My newest charcoal pulverization method is to put it in a box and take my newest invention (3 two by fours nailed together so a 6 x4), and smash the crap out of it. This seems to work well and I do it on a windy day so the soot particles blow away.
To Phillip Small and Malcolmf in reply to your post on page 37 re: types of char and surface properties of the char. See my views above and this article by Johannes Lehmann: Nutrient availability and leaching in an archaeological .... page 355. Also to davidgmills
Quote:
That seems to be what I am observing, as I am not attempting to go to great lengths to pulverize my charcoal.
note the particle size comments on p. 355. This gets into the idea that the Amazonian Indians didn't screen their char through a #50 screen but just sort of used it as is. The whole idea is that we don't know what kind of char, what temperature, what size works best but I think we need all of it! http://www.css.cornell.edu/faculty/l...%20Lehmann.pdf
To Phillip Small very bottom of page 37 on N2O, CO2, and methane emissions form Terra Preta soil. There does seem to be a fair amount of evidence that the charcoal in the soil adsorbs some of the microbial gas emissions. I am currently trying to find articles and evidence that when the charcoal does this it may possibly use the oxygen to oxidize some of the stable charcoal into more labile forms for the microbes to use. Not a lot of information out there and what there is talks around the subject. We do know that charcoal does breakdown but the exact methods are still unknown. If anyone has any information on this please post.
To all on the glomalin/humus ideas. My background is in Physics and via the chemistry that I have had I remember that reactions want to become stable. I think that same principle applies to soil. The high CEC of Terra Preta means that there are lots of ions wanting to go lots of places and bind to lots of sites. That’s one of the things that make TP good for plants. In this process the side chains of the fresh charcoal become oxidized and the charcoal becomes more recalcitrant, and the organic molecules in the soil head towards humus/humin and (I haven't read enough to be sure), possible towards the glomalin that has been mentioned in previous posts.
To all:
In all my research on Terra Preta the one thing that is constant is the charcoal/carbon in the soil. In looking at the physical and chemical properties of carbon the one main fact is that it adsorbs both solid and gaseous compounds. That’s why activated charcoal has so many applications where it is used to purify both water and air.
What the charcoal in the soil does it prevent leaching by water and gas emissions from microbial respiration so that what is in the soil stays in the soil except for plant growth. Of course we do get some leaching and some gas emissions so the process is not perfect.
When we calculate how much carbon we can sequester into the soil we need to take into account the reduction of CO2 emissions that carbon in Terra Preta prevents and the fact that is it then stored as soil organic matter.
So when calculating the carbon sequestration benefits we need to take into account:
1. actual carbon put into the soil
2. reduction of CO2 emissions and increase of SOM (made from carbon/stores carbon)
3. the amount of carbon taking from the atmosphere by increased biomass production due to soil fertility (if charred and put back into the soil)
So for storage of carbon Terra Preta is better than we thought!
of his gasifier. If "a picture says a thousand words", this says a million.
The device will produce charcoal if you can find a safe method of stopping it when it switches from wood gas burning to charcoal burning, e.g. a cover to shut off all air supply.
I've created this thread from the existing posts I found via a quick search of the parent thread. If you notice I've missed a post on this topic, please let me know either through PM or in the "Quick Apology" thread so we can ensure it's brought over:
Re: Terra Preta 
James, 
