permaculture

["Vital Scherrer" <vital233@hotmail.com>]

Hello,
Discussing about carbon in mulches, I wonder whether the article below has 
ever been published and reviewed in this forum; as I am new here I would 
have thought it did. But as it is one of the most important issues, it's 
certainly vital to bring it up (again?). I would appreciate it to get 
information about experiences and possibly alternative furnace constructions 
and -methods to produce the low temperature charcoal, possibly suppliers of 
furnaces or even of the charcoal.
Cheerio
Vital, Madeira, Portugal


SAVING THE PLANET WHILE SAVING THE FARM
How soil carbonization could save the planet while it saves the family farm

A personal essay in hypertext by Scott Bidstrup
It is not enough to try to browbeat business as well as the population into 
giving up fossil fuels... Fossil fuels are simply far too convenient, cheap 
and easy to use for their use to end anytime soon, no matter how repressive 
government gets. If we are going to solve the problem of global warming, it 
won't happen by denying the problem, as conservatives tend to do, or by 
browbeating people into spending more money on less convenient alternative 
energy sources, as liberals would seem to prefer. The only realistic 
solution - what must be done - is to make the addition of carbon dioxide to 
the atmosphere a non-problem.

For a long time, soil geologists and archaeologists faced a mystery.

The mystery was a nagging one, but not an urgent problem that impelled soil 
scientists to travel to the Amazon jungles to solve. But it was an 
intriguing problem which was finally solved by an archaeological survey - a 
survey which involved soil geology.

For many years, it had been known that among the extremely weathered and 
infertile soils of the Amazon basin, some of the least-fertile soils on the 
planet, there are large, widespread patches of highly fertile soil. Soil 
that is not just fertile, but extremely fertile - so fertile and so valuable 
that for many years it has actually been mined and exported. What was the 
difference? The only visible difference was that the fertile soil is black, 
pitch-black, and grew just about anything with ease, and the infertile 
soils, just a few meters away, are a pale yellow color, and are so infertile 
that almost nothing except native weeds can grow in them.

Archaeologists had long noted that in the black soil, there were also 
abundant pottery fragments, apparently left behind by pre-columbian 
aboriginals. Not just a few, either, but in many places in the black soil, 
the pottery fragments were so numerous that they made up as much as ten 
percent of the soil volume - but the pottery fragments only occurred where 
the soil was black. The source of the pottery fragments was a considerable 
mystery to the archaeologists, as nothing was known about where they came 
from or how they came to be there in such abundance. So a few years ago, 
archaeologists undertook a survey of the black earth ("terra preta" as it is 
locally known) areas to determine just where the pottery came from and how 
many indigenous peoples must have been living in the area.

The results of the survey were startling indeed. The black earth areas, 
about twice the size of Great Britain, together had supported as many as 
three million people - more than had been believed to have ever inhabited 
the entire Western Hemisphere at any one time. They had realized that the 
black earth was fertile, but had never imagined that the Amazon basin could 
be so hugely productive.

The survey solved another mystery, too, this one a historical mystery. In 
the year 1541, the first European exploration of the Amazon river occurred 
when Francisco de Orellana, a Spanish conquistador, floated down the Amazon 
river from a tributary in the Peruvian Andes to the mouth in the Atlantic, a 
distance of more than five thousand miles. The privations of the journey, 
lack of food, prevalence of jungle diseases and the like took their toll, 
and the crew of Orellana's expedition died, almost to a man. By the time he 
returned to Spain to tell his tale, he alone remained. His epic history 
included stories of huge cities, with markets bulging with foods of every 
description, and of course, gold. Orellana's tales contributed greatly to 
the legend of El Dorado. But when the Spanish finally returned to the Amazon 
eighty years later, all they found was empty jungle, with a few scattered 
natives subsisting off of the rain forest. Oreallana's descriptions were 
dismissed as fantasy by generations of historians. Impossible, they said, 
couldn't have happened.

What we now know is that the Amazon did, indeed, support large communities 
of aboriginal peoples, which seem to have mysteriously vanished into the 
hunter-gatherer tribes seen by later European explorers. But we also know, 
from archaeological evidence, that they may (and probably did) survive into 
post-Columbian times, only to quickly disappear. And it was apparently the 
disease brought by Orellana and his men that caused the sudden decline, as 
European contact did in so many other places. When the cities were swept by 
disease, they were abandoned, and the jungle quickly reclaimed the sites, 
leaving nothing behind for explorers to find eighty years later. So, as we 
now know, the legend of the rich cities of the Amazon did have a basis in 
fact. And it was the terra preta, the black soil, which sustained that vast 
culture, that was the real gold of El Dorado.

All this got the curiosity of the archaeologists really going. What could 
possibly make the difference - why was the terra preta so fertile, when the 
soil around it was so sterile? They finally felt compelled to call in soil 
geologists to find out. And the discovery they made astounded them.

The soil scientists studied every possible aspect of the black soil - its 
minerology, its geological history, its chemistry and its physical 
structure, but what they discovered was truly amazing to them as well as to 
the archaeologists. The mineral content of the soil is identical to the 
sterile yellow clay - there was no geological or mineralogical difference. 
The only difference between the sterile yellow clay of the Amazon river 
basin and the incredibly rich and fertile terra preta of that region is the 
presence of finely divided charcoal powder in the terra preta.

Apparently, the indigenous farmers of the region had taken to carbonizing 
their farm waste, grinding the charcoal to a fine powder, and adding it to 
the soil. The richest soil samples, those with the greatest fertility, were 
between twenty and forty percent charcoal by volume, and the charcoal was 
powdered to a fine powder - a few hundred microns was the average particle 
size. There are few bits of charcoal any larger than a quarter of an inch in 
size. The charcoal was produced in a low-temperature process, not heating it 
too excessively. It contained within its molecular structure, plant resins 
that were heat stabilized.

Because nobody had ever bothered to investigate powdered charcoal's effects 
on soil fertility carefully, soil scientists had simply always assumed that 
charcoal when added to the soil, was inert and its effects primarily 
mechanical. Chemically, it is very stable at ambient temperature - even on 
geological time scales - and does not participate in chemical reactions, so 
it was simply assumed that any nutrients it trapped were simply unavailable 
to plants. Close investigation of the terra preta situation proved this to 
not be the case. Not at all.

What the soil scientists, working with microbiologists, discovered was that 
a community of bacteria exists in symbiosis with the root hairs of plants. 
The bacteria produce enzymes that release the mineral ions trapped by the 
heat stabilized plant resins in the charcoal and make it available to the 
root hairs of the plant as nutrients. In return, the plants secrete 
nourishment for the bacteria. Not only that, but the resins within the 
charcoal act like an ion exchange resin, adsorbing traces of mineral ions 
onto the charcoal particle surfaces from the rain water, and trapping it 
within the charcoal's molecular structure, where it can be held for 
centuries - until the soil bacteria associated with a root hair come along 
and secrete the enzymes necessary for it to be released once again. So the 
trace minerals always present in rainwater actually act as a fertilizer - 
providing the nutrients needed by the crops, year after year. The secret of 
the soil fertility of the terra preta was finally understood. And it was 
understood how the indigenous farmers were able to produce bumper crops year 
after year, decade after decade without a single application of chemical 
fertilizer and without wearing out the soil.

This was confirmed when the soil scientists grew some test plots. The 
results were seen recently on a Discovery Channel special about this 
Amazonian mystery. Viewers saw three plots - the first, the control plot, 
was natural Amazon yellow soil from which the native vegetation had been 
removed. The second was identical to the first, except that chemical 
fertilizer was added. And the third was a plot identical to the first, but 
to which charcoal was added along with a normal dose of chemical fertilizer. 
The results were dramatic. On the entire control plot, there grew only a 
single plant, pathetically stunted, which did not flower. On the fertilized 
plot, there was a small growth of stunted plants, few having produced seed 
heads - clearly what could only be described as a failed crop. The charcoal 
plot was dramatic - lush growth with an abundant crop of seed heads - a 
bumper crop indeed.

This discovery also solves a mystery that has puzzled farmers in tropical 
regions for years. It has long been known that growing sugar cane increases 
soil fertility. Over the years, soil in which sugar cane has been grown can 
become quite fertile - the opposite of what happens with nearly all other 
crops, which tend to exhaust soil. We now know the reason why - sugar cane 
fields are normally set alight before harvesting. The flames sweep through 
the field, burning off the thicket of leaves and leaving only the cane 
behind, making it much easier to harvest. What is left behind also includes 
a small amount of charcoal, which finds its way into the soil, gradually 
adding to its fertility, year after year. Where I live in Costa Rica, sugar 
cane, which is a low-value crop, is often grown simply to keep the farm 
alive and sustain the soil, while the farmer tries to find an alternative 
use for his land. It is a sad situation, but now there is an alternative. It 
is to make the land economically productive once again, by doing 
deliberately what the cultivation of sugar cane does accidentally.


Saving The Family Farm

If the required amount and type of charcoal is added to soils in tropical 
and semi-tropical regions where these symbiotic bacteria are known to be 
able to flourish, the chemical inputs required to sustain agricultural 
productivity can be greatly reduced. In these regions, the high rates of 
rainfall over thousands and millions of years have weathered most soils to a 
very poor level of fertility. Soil infertility caused by intense weathering, 
and the intensive use of costly chemical fertilizers this makes necessary, 
is the greatest single problem faced by farmers in tropical and semitropical 
regions. And that problem can now be solved - even for soils so thin and 
poor that by themselves they can grow little but a few hardy weeds.

Of course, this gives such a farmer a considerable advantage in economic 
terms over his competitors - while his competitors are spending large 
amounts of money on chemical fertilizer and other soil amendments, he is 
spending nothing - only the cost of carbonizing his farm waste, grinding the 
charcoal to a powder, and tilling it into his soil, and then only till the 
optimum level of carbonization is achieved. And as we shall see, this can be 
done at an acceptably low cost, even by farmers in developing countries. An 
additional marketing advantage is that he can maintain soil fertility in an 
organic manner, helping greatly in certifying his farm as an organic farm, 
which can mean an increased value for the produce he sells. Soil amendments, 
primarily fertilizer, are by far the greatest single cost that a farmer in 
the tropics faces. With proper soil carbonization, that cost simply goes 
away. Farms that were economically marginal or failing, now can suddenly 
become not only highly productive, but highly profitable. Instead of selling 
the farm that has been in the family for generations, the tropical farmer in 
the third-world now has the option to go back into farming - and make more 
money than he could ever hope to make by working for wages or struggling to 
run a small business in the city.

Carbonization of farm waste has traditionally not been practiced, because it 
has traditionally been slow, inefficient, messy, labor intensive and 
produces a product for which, until now, there has never been enough use to 
justify all the trouble - and it has always been assumed to have limited 
value as a soil amendment. It has always been easier to just plow farm waste 
under, and allow it to rot. This is fine, but it produces only modest 
improvements in soil fertility, and they are largely temporary. But as we 
shall see later in this essay, soil carbonization by small farmers should 
now be practical, because I have developed a charcoal furnace specifically 
designed to carbonize farm waste - in a device that is cheap and easy to 
build, and almost a hundred percent efficient, as well as easy to use.


Saving The Planet

If practiced on a truly large scale, the carbonization of soil in the 
tropics and subtropics can not only solve, but might even reverse the 
problem of global warming.

That is quite a sweeping statement, but it is true, as we will see. To 
understand how this is possible, you need first to understand the biospheric 
carbon cycle.

This is a very simplified version, so please, if you are a scientist or 
other academic, don't write me to correct the details. The intent of the 
following explanation is only to outline the carbon cycle in its very 
broadest dimensions, so that non-technical readers can understand my 
explanation of why soil carbonization could have a major, beneficial impact 
on global warming.

The carbon cycle begins with atmospheric carbon dioxide, the greenhouse gas 
we all know and are growing to hate. It is a natural part of the atmosphere, 
however, and prior to the widescale use of fossil fuel in industry, the 
concentration of carbon dioxide in the atmosphere was roughly 250 parts per 
million by volume. Digging up carbon-based fuels out of the ground and 
burning them, adds to atmospheric carbon dioxide, since carbon dioxide and 
water vapor are the primary combustion products of burning fossil fuels. A 
century and a half of burning (oxidizing) fossil fuels, most of which 
consists of carbon, has raised the concentration of carbon dioxide in our 
atmosphere to roughly 360 parts per million. We are burning fossil fuels at 
such a rate that this value is increasing at roughly 10 parts per million 
per year. This does not sound like a lot, but carbon dioxide is extremely 
efficient at trapping heat in the atmosphere, and that is why its influence 
is all out of proportion to its concentration, and that is why increasing 
its concentration even a little bit matters a whole lot.

As you may recall from your high-school science classes, plants breathe in 
this carbon dioxide (which is all the same, regardless of whether it is 
natural in origin or comes from human activity), and through photosynthesis, 
combine it with water and turn it into the carbohydrates that make up the 
plant - the sugars, cellulose, lignin and other materials. When the plant 
dies, this carbon, which was sequestered (locked up) temporarily in the 
plant's tissue, is oxidized by decay organisms and is released back into the 
atmosphere in the form of carbon dioxide. The cycle is complete - the carbon 
dioxide becomes available for another plant to absorb. The theory of 
planting trees to slow global warming is that trees sequester this carbon in 
their plant tissues - wood - for centuries. But of course, they eventually 
will all die and rot away, and so the carbon dioxide they are supposed to 
sequester will eventually be released back into the atmosphere anyway. Other 
schemes have been suggested for sequestering carbon dioxide - usually by 
liquifying carbon dioxide and dumping it on the ocean floor (with unknown 
and unpredictable consequences for ocean ecology) or pumping it into 
abandoned natural-gas wells (again with unknown and unpredictable ecological 
consequences). But all these schemes are expensive and produce no 
economically useful outputs, so implementing them is problematic at best - 
it would have to be done by a government program, because there is no 
economic incentive for the private sector to do it.

There is another way to sequester the carbon and one that does indeed have a 
private-sector incentive associated with it. Charcoal consists almost 
entirely of carbon - by weight, carbon makes up close to 100 percent of 
charcoal. And charcoal is chemically stable - it does not react readily with 
either water or atmospheric oxygen at ordinary temperatures, so once in the 
ground, it will remain there for geological time scales. Indeed, scientists 
routinely find charcoal from forest fires in sediments laid down during the 
age of the dinosaurs and before. So once added to soil, carbon in the form 
of charcoal will remain there until it is physically separated out or 
oxidized in the interior of the earth. This process of geological 
consumption simply does not happen on any kind of time scale with which we 
need to concern ourselves. Charcoal is also easy to make - simply heat up 
any solid biological product to a temperature of about 470 degrees 
Farenheit, and the carbon atoms give up most everything else they are 
attached to - which comes off as the vapor we know as smoke. The carbon 
atoms simply reattach themselves to each other, and what we have left is 
elemental carbon - in the form of charcoal. And as we have seen, if farmers 
knew what it could do for them, they would have a major financial incentive 
to create charcoal from their farm wastes and add it to their soil, 
sequestering it permanently.

So how can this possibly have a measurable effect on the atmosphere? After 
all, the atmosphere of this planet is really big - a hundred miles deep and 
covering millions and millions of square miles of surface area. Even at the 
small fraction of the atmosphere that is carbon dioxide, that amounts to a 
truly staggering amount of carbon that we are swimming in - billions of 
tons. How could a bunch of farmers, carbonizing their farm waste and plowing 
the charcoal under, possibly have that much of an effect? The answer is 
numbers. Millions of farmers, all doing this together, could have an 
enormous impact, bringing atmospheric carbon dioxide right back to its 
pre-industrial levels. Here are the back-of-the-envelope calculations that 
show how this is plausible and even feasible:

The weight of all the air above the earth's surface amounts to 14.7 pounds 
per square inch at sea level - that is the same as atmospheric pressure. 
This means that every square inch of earth's surface (at sea level anyway), 
has 14.7 pounds of air resting on it. For the sake of convenience of 
understanding what is happening and visualizing that in our minds, let's 
convert that to weight per square foot. There are 144 square inches in a 
square foot, so that means that the weight of the earth's atmosphere at sea 
level is 2116.8 pounds, or a little over a ton per square foot (we don't 
feel that pressure, because we are immersed in the air, which presses up as 
well as down, and from the inside as well as the outside on us, cancelling 
out the pressure). We know that the volume of that air is composed of carbon 
dioxide to the extent of 360 parts per million, but since carbon dioxide 
weighs more than air, for the purposes of these calculationswe need to 
convert that composition by volume to a corresponding composition by weight. 
It turns out that at equal temperature and pressure, carbon dioxide is 54% 
heavier than air, so if we multiply our 360 parts per million by 1.54, it 
turns out that the composition of the atmosphere is currently 556 parts per 
million carbon dioxide by weight. It follows then, that of the 2116.8 pounds 
that the atmosphere weighs per square foot on the earth's surface at sea 
level, 556 parts per million of that weight is carbon dioxide. Divide the 
2116.8 by a million and multiply the result by 556, and you will have the 
weight of the carbon dioxide only, per square foot, that is bearing down on 
the earth's surface. The result is 1.17 pounds. But carbon dioxide includes 
a lot of oxygen, and if we want to know how much charcoal that would 
represent, we need to get rid of the oxygen in the carbon dioxide. Well, it 
turns out that 37% of the weight, roughly, of carbon dioxide is actually 
carbon (the rest is the oxygen), so we need to multiply the 1.17 pounds by 
37% to get the weight of the carbon only. Turns out to be 0.43 pounds, or 
6.92 ounces. If you turned all the carbon dioxide in a column of air of one 
foot square and as high as the top of the atmosphere into carbon (or 
charcoal), that is what the resulting carbon would weigh - 6.92 ounces.

Obviously, since atmospheric carbon dioxide is a vital, even critical part 
of our biosphere, we don't want to get rid of it all. We want only to get 
rid of the part that mankind has added to the atmosphere since the 
Industrial Revolution began. So if we calculate what percentage of current 
atmospheric carbon dioxide has been added by man, the percentage works out 
to 44%. So of our 6.92 ounces per square foot, the Industrial Revolution is 
guilty of adding a hair over 3 ounces per square foot.

The rub here is that farmers, to have a significant impact on global warming 
by adding charcoal to their soil, will have to add this amount for all the 
planet's surface area, land and ocean alike, not just the area of the 
planet's surface under cultivation. So we need to know how much of the 
planet's surface area is under cultivation in tropical and subtropical areas 
to determine how much they would need to add to save our skins. Turns out, 
according to United Nations Food and Agriculture Organization and from other 
sources, that pretty close to 1.6 percent of the surface area of the planet 
is given over to agriculture in tropical and subtropical regions. To reset 
the composition of the atmosphere to pre-industrial levels, the farmers in 
those regions are going to have to add to their soil, charcoal equal to 
three ounces divided by 1.6% - or in other words, 190 ounces per square foot 
of cultivated area.

This amounts to 11.8 pounds of charcoal per square foot of cultivated area. 
Depending on the density of the charcoal and the density of the soil, this 
is roughly the amount needed to get the optimum 30% by volume to a depth of 
about three feet. Just perfect! Just what the farmers need to do! And just 
what the planet needs to give us a second chance! So if every farmer in the 
tropics and subtropics got on the ball with this program, we could 
completely undo all the damage that we have done to our atmosphere with our 
fossil fuel addiction and put things right.


Getting The Job Done

It strikes me that getting this job done should be politically feasible. 
Everyone involved should be all for it - it gives conservatives a graceful 
way out of their denial, it gives liberals a project that does not involve 
government forcing people to do what they do not want to do, it gives 
farmers a strong economic incentive to sequester and bury huge amounts of 
carbon, and it gives industry an incentive to help make it a reality, by 
creating a means, through the Kyoto Protocol, of ridding itself of a 
troublesome pollutant in a cheap but an environmentally benign (and even 
beneficial) manner.

So here is how I propose to make this happen. First, the big environmental 
NGO's need to get on board. They need to see what is at stake here, and how 
this could be a huge boon to the environment. They need to get to work in 
the tropics and subtropics of the third world, providing the tools and 
knowledge, and showing the farmers how they can benefit from this 
technology.

The governments can get involved by offering Kyoto-Protocol carbon tax 
credits to farmers. Since it is the farmers who would be doing the 
sequestration, they should be the ones to benefit under Kyoto - and it gives 
them further incentives to participate, besides the improved productivity of 
their soils. It can be another income stream for the farmers if the 
governments set up the programs in the proper way.

Industry should benefit by building the charcoal furnace equipment I will 
describe below, and unrelated industries should benefit by finding 
themselves under less pressure to change products and processes to curtail 
carbon dioxide emissions. This should give industry, particularly the fossil 
fuel industry, an incentive to help encourage soil carbonization by 
third-world agriculture, so industry can go on doing what it is doing now.

In tropical and semi-tropical regions such as Costa Rica, where I live, and 
other parts of Latin America, where large-scale family farming and 
industrial-scale farming is already well established, I foresee large 
companies getting into the soil carbonization business, because farmers 
simply can't create enough charcoal to meet their needs - it just isn't 
practical over a reasonable timeframe. So bringing in someone else to do the 
job makes a lot of sense. The broad details of the business plan of such a 
company would work something like this - the soil carbonizing business would 
own farms where kenaf, bamboo and other high-biomass crops are grown as a 
feedstock, or be located near sugar cane crushing mills, where large amounts 
of baguase (crushed cane fiber from which the juice has been extracted) is 
available cheap or for free as a feedstock for the charcoal production 
process. The company would have large scale charcoal furnaces, a scaled up 
version of what I will describe below, with which they will produce charcoal 
powder on a grand scale. The company would approach landowners with a 
proposition - it will finance the carbonization of all the farm's cultivated 
soil through a lein, and the farmer can pay back the lein through the 
improved crop yields over a period of several years - the farmer pays only 
for increased yields, and for only a set number of years. This is the 
guarantee of results to the farmer - if there is no increase in yields, 
there is no cost to the farmer. Once the lien is satisfied, additional 
profits resulting from increased productivity, from then on, are the 
farmer's. If the farmers stand to lose their farms anyway from the lack of 
productivity and high operating costs they already face, and can see the 
results on neighbor's farms, few would refuse.

In Africa, South Asia and other areas where subsistence farming is the norm, 
I anticipate that it would be the NGO's and government programs that would 
provide the means and incentives, the details of which would have to vary 
from region to region. Governments would provide the charcoal furnaces 
(financed through foreign aid, most probably), the NGO's the know-how, and 
the farmers would do the work. They would concievably have a single 
small-scale carbon furnace, providing charcoal from their field waste for 
use in domestic cooking use as well as the carbonization of the soil on the 
farm. Once the farm's soil is adequately carbonized, the farmer could sell 
his furnace to a neighbor, or use it to produce charcoal for briquette 
manufacture - an additional income source.


A Cheap, Easy-To-Use And Efficient Charcoal Furnace

When I began researching for this essay, I quickly discovered to my dismay 
that the technology for producing charcoal has not changed much, literally, 
in centuries. It is still done, for the most part, the way it always has 
been done.

It was obvious to me that if I were to persuade large number of people to 
start producing charcoal, and on a large scale, that I had to come up with a 
more convenient, faster, more efficient and less messy way of doing it. So I 
started thinking about how it could be done in the manner needed. I thought 
about it for some time, and finally, in a flash of inspiration, the answer 
came to me.

A tubular furnace, using an ordinary piece of large diameter iron pipe, 
heated by a solar energy reflector, would be the answer. Not dependent on 
its own output as a heat source, any solid organic material feedstock could 
be used - even wet leaves - and the product would take minutes to produce, 
rather than hours or even days as is needed for the usual methods. And 
virtually all the charcoal produced would be available as product, since 
none is consumed to provide the heat for the process. Push the raw, even wet 
feedstock in one end, and minutes later, finished charcoal comes out the 
other. What could be simpler or easier?

So on consideration, the design worked out to something like this - a piece 
of pipe, blackened on the outside to facilitate the absorption of the heat, 
about three or four inches inside diameter, and about ten to fifteen feet 
long, is suspended over a trough reflector, shaped into a parabola in 
cross-section, with the pipe suspended at the focal point, parallel to the 
length of the trough. The trough would be about eight to ten feet wide, and 
is lined on the inside with the solar reflectorizing material, which is 
nothing more than shiny metal - in a pinch, aluminum foil, shiny side up, 
could be simply glued to ordinary sheet metal to provide the shiny surface 
(the shiny aluminum surface could be sprayed with clear acrylic to preserve 
the shine). The resulting device is mounted with the length on an exact 
east-west line. If this is done, the only adjustments that need to be made 
to keep the furnace operating at peak efficiency is to keep the reflector 
tilted to the current seasonal sun angle. No hourly or daily adjustments 
need be made. Simply push the feedstock in one end, and if it gets heated to 
more than 470 degrees during its transit through the pipe, out the other end 
comes low temperature charcoal, ideal for soil carbonization. Easy as that.

For a third-world farmer without access to electricity, the furnace would be 
pretty much as described, with the feedstock being loaded from a small 
bin-like arrangement welded to one end of the furnace pipe. Feedstock would 
be pushed into the furnace pipe with tool consisting of a small pipe as long 
as the furnace pipe, on which a disk is mounted on the end, a disk somewhat 
smaller than the inside diameter of the furnace pipe. The disk's purpose is 
simply to force the feedstock into the pipe and through it, and clear 
blockages as needed. As feedstock enters one end of the pipe, the finished 
charcoal is simply pushed out the other. Gasses driven off by the heating 
exit through the feedstock end - the other end is left completely blocked by 
charcoal, which precludes the entry of oxygen and thereby keeps the 
efficiency high.

There are endless variations on this theme that are possible. For industrial 
furnaces, the farmer's feedstock tool could be replaced by an auger screw. A 
gearmotor, switched by a thermal switch, would come on when the sensor 
detected that the temperature of the furnace pipe exceeded the setpoint, 
turning the screw and loading the feedstock from the bin and carrying it to 
the far end of the pipe. It would run until the sun went down or behind a 
cloud, and the temperature dropped below the setpoint. Loading of the intake 
bin could be done automatically, too, with another auger screw or a conveyor 
belt, which could load several furnaces at a time. Output could drop into a 
hopper emptied by yet another auger screw.

Another variation would be to collect the outgassing products - smoke - 
which on a large scale, would be worth doing, as the condensate could be 
processed into useful petroleum substitutes including terpentine, or burned 
on cloudy days to provide the heat necessary to keep the production going. 
This would also improve environmental performance by reducing the air 
pollution that would result from releasing the smoke into the air.


Conclusion

The obscure discovery made by archaeologists and soil geologists working in 
the Amazon basin a few years ago could have huge repercussions - while it 
saves millions of farmers in the tropics and subtropics from lives of 
poverty and destitution, it could also save the world, literally, from the 
folly of modern man by learning from the discovery of those long-dead 
aboriginals who made this discovery all those years ago.

The only question that remains is whether we will apply the lesson in time. 
The tools are there; we have the knowledge and technology to get the job 
done. We have the incentives to do it. We have the urgent need to get on 
with the task. Let us not be ignoring what we need to do, and can do. Not 
only can we better feed ourselves and help millions overcome poverty in the 
process, but even more importantly, we can save our very home, the only one 
we have, from the mess we have made of it. There is hope for the planet 
after all. But we had better get busy.


Internet Resources:

A good overview of what is currently being done in terra preta research and 
applications has been the subject of a recent symposium at the University of 
Georgia.

The "Terra Preta Homepage."

Cornell University is pioneering some research in terra preta, and has an 
extensive web page describing their activities.

Source URL: http://www.bidstrup.com/carbon.htm
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