adam + partner appropriate technology
adam + partnerappropriate technology

low-cost charcoal production



Low-cost retort kiln  called the "adam-retort"® 
or called

ICPS    (Improved Charcoal Production System)

(photo adam: AUROVILLE/ INDIA/ Earth Building Unit) The ICPS is a modern, innovative and environmentally friendly system to produce charcoal from biomass. (low-cost retort kiln)

Did You know:
CHARCOAL from RETORT SYSTEMS can often serve as a replacement for fossil fuels,

thereby having a neutral effect on CO² exchanges.
This makes a significant positive contribution to the preservation of our environment!
Also using charcoal to improve soils for agriculture (bio char) becomes more and more important.


Advantages of the "adam-retort":

1) High economy and better efficiency of approx. 35%  (Instead of about 18% efficiency compared to the traditional systems; calculated from dry weight).


2) Recycling and clean combustion of the pyrolysis gas during the 2nd phase of operation (retort-system) results in a low-emission of carbon monoxides, methane, etc.  during the charcoal production! The effective operation of the retort and carbonization of the biomass takes only ~10 hours, (cooling not included).
A retort system
reduces the emission of harmful volatiles into the atmosphere
to about up to 75%! (Compared to a traditional earth-mount kiln).


3) Low investment costs of about ~1000Euro and a simple construction with locally available materials. (Costs were about 300 Euro in Kenya in 2004, but now with raising steel prices costs increased...) .


4) About 3m³ of biomass (corresponding to approx. 600kg to 900kg wood, coconut shells, compacted saw-dust briquettes, etc., dry weight, water not counted, or ~1-1,5 tons of wet wood) can be converted to ~250kg charcoal (but also 350kg was already received) per batch.
Per week about 2-3 batches of biomass can be carbonized which is corresponding to about ~ 1/2 ton or more of charcoal per week and unit. (3 batches can be perfomed with nightshift)


5) An effective 30 hour total production cycle (known as batch and including cooling) and a simple operation of the plant results in an increased income for its operators.
The right system to be used at forest projects, sustainable energy-wood plantations and charcoal makers in rural areas or for semi-industrial production.


6) Only waste wood or residual biomass needs to be burnt (~50kg) in a separate fire box to dry and heat the wood and initiate the carbonization process during the 1st phase.


7) The production of "wood vinegar" is possible during the 1st phase of operation.

perspective drawing of the "adam-retort" a masonry unit, view from back side

The issue of the introduction of environmentally friendlier procedures for charcoal production in countries such as Asia, Africa and South America - is one that is badly in need of our attention.

Currently Kenya uses ~2 million tons of charcoal for household purposes per year. Zambia’s situation is comparable to Kenya’s, using approximately 1 million tons of charcoal per year. Many other third world countries are showing similar figures as well.

This charcoal is mainly manufactured with an earth-mound-technology, originally used in the Middle Ages. To create 10kg to 15kg charcoal using this method, about 100 kg of wood is needed. Here, the efficiency ratio is only 10%-15%.

There is, however, an alternative method available. Known as ‘retort-technology,’ this is the method used in Europe to manufacture charcoal on an industrial level.

These industrial plants are unfortunately impracticable in the rural areas of the target countries, because the investment and maintenance costs of the process are too high.

After much consideration, as well as experience with the building of a bio-coal plant in Burundi/East Africa, we have succeeded in developing a concept for innovative retort-kilns built with locally available materials. We have confidence that the retort-kiln can be accepted by the population and be widely spread. The retort-kiln was developed according to the principles of ‘intermediate’ or ‘appropriate technology'.

In 2004 in India/AUROVILLE the development of the retort model was furthered – now being built in Kenya, we can see how the low-cost retort-kilns are helping aid a more environmentally friendly method of charcoal production.

The unit is called ICPS (Improved Charcoal Production System) or „adam-retort“ and has the advantages which are mentioned at the beginning of this page.

* The concept of the ICPS / “adam-retort” is that the retort works in 2 stages – the first and the second phase. In the first phase the wood in the retort chamber is dried by hot flue gases and the carbonization is initiated. Hot flue gases are produced with cheap waste wood in an external fire chamber. By waste wood we understand branches, crust, charcoal dust and other residual products from agricultural processes, such as coffee husks. About ~50 kg of waste wood (dry mass) is burned per batch.


During traditional charcoal production a part of the ‘good’ wood must be burned down in order to carbonize the rest of the wood.

Retort: as soon as the water in the wood has evaporated, the smoke is sufficiently hot and the first inflammable wood gases appear, the smoke is now rerouted by a unique method and burnt in the hot fire chamber, reducing pollution. This additional energy is used to heat up the wood chamber and to further accelerate carbonisation during this second phase

In the traditional carbonisation process- smoke smoke is emitted into the air for up to 4 – 14 days. The smoke created by the “adam-retort” will be much less within approximately 10 hours of operation- with some of the smoke being burnt off in a fire box. If the carbonisation begins in the morning, the retort-kiln can be closed by the evening. The charcoal cools overnight by a special cooling method. By the next morning or midday- the charcoal is ready to be evacuated from the wood chamber.

The retort unit can be built for approximately ~1000 Euro or more in countries with low labour costs.

About 3m³ volume, or 600kg-900 kg wood (dry weight) can be loaded, from which 200kg-350 kg of charcoal can be created.

Our calculations in Kenya mean the initial investment costs can be paid back in about three months, from the sales of the charcoal.

The “adam-retort” can be built in approximately one week by a ‘Retort-Team’ consisting of 1 trained bricklayer and 1 - 2 assistants. The chamber of the retort kiln is build from simple bricks or even unburned earth blocs, also hollow bricks are suitable.

Photo: PHASE-II burning of wood gases (methane) and recycling of the heat gained to push carbonisation



It makes sense to introduce the “adam-retort” at forest projects or other areas which cultivate wood energy plantations. The farmers are more motivated to plant energy trees because the wood gets a higher economic value because of an about doubled recovery rate for the charcoal! It's also recommended to use the “adam-retort” as well in areas where sustainable trees exist. This is the case in many areas of East- and South Africa where the Lelechwa or Prosopis wood or grows. The local farmers call these shrubs ‘weeds,’ partly because after cutting they grow back with renewed vigor. Their hard wood creates an excellent charcoal. The burning of coconut shells to create charcoal is also a possibility.

A ~75% reduction of environmental damage has been recorded by an English retort manufacturer by burning the methane gases. Wood consumption is reduced by over half, while maintaining the amount of charcoal produced. With the retort-technique charcoal of a high quality is obtained – one extra suggestion has been to market this charcoal to the medical sector.

We do not advise the introduction of charcoal; it is better to burn wood directly. In many countries, however, charcoal use is socially determined, or traditional, as regards specific meals prepared. In areas where this kind of high charcoal consumption takes place, it is more appropriate to produce it with more efficient, more modern and environmentally friendlier methods, such as the “adam-retort.”

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Also information on the ICPS in other languages is available on request: German, French, Spanish and Portuguese. 
(scda2 (@) ymail. com ) NEW e-mail  since July 2009 !

update: 1.July 2016

Check the videos about the "adam-retort" under:

or search under with keywords "charcoal, retort".

and another video

"adam retort Panchabhuta Conservation Foundation", India 2016

Partly you can find this information also under: 


Some other references (16 pages, check page 9 & 6):

Building a Biochar Oven (2016)

or in French language:


/ page 145:


Kick-Starting Africa’s Carbon Markets, The potential for programmatic CDM. Page 11, 62, 63: “adam-retort”:


Forrest Fines No1/2009, page 26-27: (German) "Holzkohle, ungeliebt und unvermeidbar…"


"adam-retort" built in Mali (Youtube 2012): Sustainable Charcoal in Mali


REFERENCES on the "adam-retort":

Phone call with Mr. Luggy from South Germany (Bavaria): He is a farmer and he is doing carbonisation occasionaly when time allows. He is very satisfied because he can do charbonization now alone as a single person (traditional carbonisation needs a team of persons). He also appreciates the he can complete carbonisation in a day or two. He receives about 220kg per batch of charcoal from beech wood. He is not using insulating lids on the top of the wood chamber (which could increase the yield).
He is operating the retort since October 2006, Luggy, Bad Kohlgrub,
Phone call with Alex jun.: together with his father he is running a farm near the border to Angola. They modified the retort to be used with containers and they manage to do 5 batches per week and they are running 6 retorts. The retorts are loaded with 1 to 1,5 tons of wood and they get about 350kg (!) of charcoal per batch.
Alex, (Namibia) June 2008,
Hallo Chris,
die Retorten laufen alle 3, aber sie sind nicht zur Gänze zufriedenstellend; die Risse im Mauerwerk und im Zement sind chronisch, die Temperaturverläufe sind gelegentlich ziemlich unstet, aber sie laufen.
Ich habe für die nächsten Retorten eine Reihe von technischen Verbesserungsvorschlägen um die Retorten günstiger, besser, schneller und sauberer zu konzipieren. Und als nächsten Schritt werde ich die Biester vergrössern.
Die nächsten 2 Retorten werden im Februar am Alto U. im Urwald gebaut, dann geht's am Unterlauf weiter...
Die Landesregierung von U. hat grosses Interesse an einem umfangreichen und finanzstarken Projekt angemeldet, dass noch 2009 beginnen soll; mit der Universität von U. bin ich derzeit in Verhandlungen über gemeinsame Forschungsarbeiten zum Thema Holzkohlegewinnung.
Die Vorgehensweise zur sogenannten "White Charcoal" koenntest Du mir mal bei Gelegenheit erlaeutern, wenn Dir danach ist.
Bis dann mal, Gruss
Manuel P. (Peru), <>, Jan.2009.
Hello Dr.Adam,
Yes we set the kiln up. We normally carbonize coconut shells. We are planning on grinding the charcoal to powder then briquetting them, perhaps you can also give us some more ideas on that. Otherwise all's well it s only the lower plate on the floor of the kiln that gets worn out quite fast, we are already doing repairs on it.       Regards
David, (Mombasa, Kenya),, Jan. 2009,
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Dear Chris,
We had made a kiln as you described and made a few
modifications for it and we had been  successful in getting very good charcoal.
Sitki Okay, (Turkey) <> 14.July 2009
Dear Chris:
....... It has been busy for us here as well, concentrating on making the "Adam-Retort" work with available US materials and of course the English measurement system that we still use here. You may be happy to know that the "Adam-Retort" is getting very popular here and many people and organisations are interested in it.
We met with Tom M. last month, to explore some next technologies, and he sends his regards to you. He spoke very highly of your work, and has recommended the "Adam-Retort" to be built by us for a bamboo char project in S. We will of course let you know how that proceeds....
As you have seen, we are well on our way to building the first few "Adam-retorts" in the US. We now have 2 under construction .............
Concerning your "CCS-Lite" (Continuous Carbonization System Lite) I am wondering whether you were able to complete the drawings of the "CCS-Lite" in July as you mentioned. We have looked at several technologies, but none of them have worked out yet. It appears to us that the "CCS-lite" is the most viable technologies for the next generation of bio char producers here.
This means that the "Adam-Retort" is the only practical charcoal retort now available even in America. There is a very great and immediate need for a "CCS" unit at least as big as the CCS-Lite, and even larger,
Please let me know how you are doing, and what the future for CCS-L might be?
We have had only the best success with the “Adam Retort”, and…
Peter H., (USA), 8.July, 09


Salut Chris,
hip, hip, cette fois (2ème charche), la carbonisation a réussi! Le four a pas mal souffert (il est fendillé un peu partout), mais nous avons obtenu un charbon de bonne qualité. Apparemment, tout le volume a carbonisé et nous devrions obtenir un rendement très intéressant. Le charbon est encore trop chaud pour être manipulé, mais nous le pèserons dès que possible.
(Dear Chris, This shot is ok! Every body here is amazed... So much charcoal in only 24 hours!)

Bonjour Chris,
oui, votre four fonctionne comme prévu!
Nous faisons des burns avec 1 tonne de bois sec (10% humidité) et
obtenons entre 350 et 375kg de carcoal exploitable (hors poussier).
Notre projet envisage de construire 3 ou 4 fours dans des zones forestières autorisées à l'exploitation.
Bien à vous, Pierre . (Translation: about 350kg to 375kg of charcoal is produced per batch, chardust put aside, the wood chamber takes about 1000kg of wood or bio mass, actually we have 389kg to 417kg as efficency is recalculated to 0% water (=900kg wood));
Pierre, (Senegal), January 2010,


Dear Dr.Adam,
.......Things progress slowly with biochar in the U.S. A real lack of functioning technology. Too many people trying to make very high tech stoves without enough money to build and test. And investors want to see what works and potential purchasers think the price is too high. Your retort-stove works and is affordable!!!........
Gloria, (USA), 10.Dec.09,


Lieber Chris,
Die beiden Oefen hier in Jaen funktionieren so weit ganz gut. Die Schwierigkeit besteht eher darin eine dauerhafte Erlaubnis der Foerstbehoerde fuer die Holznutzung (aus dem Sekundaerwald) zu erhalten. Aber wir werden das schon hinkriegen...
Fabian, (Peru, ded), March 2010,


Dear Chris,
…..The last two retorts that we built in Belize were going well (although the quality of the building materials we had available in Belize was terrible !)…
regards ian M.(UK/BELIZE), 27.April 2010,      ian. @,
Dear Chris

We are from the US and have been in touch with B. from F.F. in North Carolina. They are very pleased with the retort and….
I am so glad there are designers like you who care about the ability of people in developing countries to actually execute technology transfer with materials at hand. Thank you for putting your talents into these great projects.
Sincerely, Cassie L., (Mexico) 12.5.2010,     cassie@
Dear Dr.Chris,
What a wonderful job you are doing in the bio coal filed, congratulations......
Hippo / Ago Horizon, (USA), 21.5.2010,      agro.horizon@..

We are small farm with an educational and learning center and we have recently built an "Adam Retort"........
We had been using the barrel method for many years now but decided to build a masonry Adam Retort unit to char our stockpiles of pine and oak.So far we have successfully raised our soil PH from an initial 4.5 fast draining to a 6.1 - 6.7 PH almost instantly.
Our trials with biochar and Spinach have been outstanding and we look forward to more promising results from our lettuce...
Referred to this site by Erich , Aberdeen, N.Y., (USA), 13.April 2010,


Dear Dr.Adam,
after the 1st run we had about 30% of charred wood, the second run was 95% and the 3rd test was 100% :-). Bodun, boshunrinde@ (Nigeria), 28.8.2016

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Hello Adam, 
It has been a while that i have touched bases with you. the technology that we purchased from you in working well, though we had some issues learning the proper management of the kiln we have become proficient and getting more or less the production levels that you prescribed. We currently have 4 kilns, 3 in operation and 1 waiting to be completed.
   We are begining to market 3 products, the lump charcoal, activated charcoal ( the smaller pieces) and biochar ( the dust)......
Karl, (St. Lucia, Caribic),  karltip..@   Sept. 2015.

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Low cost, low emission design. Thank you, Palsan Abdullah, (Kuala Lumpur), Oct. 2016

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Thanks for the good wishes for X-mas!

I was very slow in building the retort, but we have finished 3 lots of charcoal with no problems. I am very happy to be able to make charcoal so fast. Blessings to you.       Frits Vandermerwe, (South Africa),   frini41...@,   Dec.2016


Hello Chris,
Yes, it has been a long time. Our two retort kilns in Kenya are working well with bagasse. We have efficiencies of about 35% although we have made some small modifications. Carbonizing bagasse is not the same as wood.
Thank you for your design.

Mark L.,  (Kenya), (, Febr. 2017


Dear Chris,
our Adam retort is working very well (but we had to replace the bottom steel sheet that burnt through)….

Louise B., (Malawi), louisebragge@, Febr. 2017


Hi Chris,
its going well with your retorts here in Laikipia/ Kenya.  We have slowed production as we are exploring the market for the charcoal.  Trying to sell some locally as they are making illegal charcoal along our boundary cutting all the acacia tree’s. Devastating!....
Nigel A. (Kenya). nigel...@,  Febr. 2017

Dear Dr. Adam,

Retort operation, it's good enough till now. The retort needs to be maintained regularly......
Vijay Pandit, (India), panvi...@, Febr. 2017


Links to other bio char projects: check 2nd page: "Who we are...."

about 550kg wet fits into the wood chamber Coconut Char can be used as a household fuel, can be used for incense making, or pressed to a high quailty charcoal for shishas (for tobacco water pipes (shisha) from Arabia). About 550kg (wet) fits int the wood chamber (photo: adam)
Indios using the "adam-retort" in the Amazonas. (photo: M.Palacios)


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Diamonds are (forever)- carbon too.
Certainly, you prefer diamonds instead of charcoals. But
chemically speaking, diamonds and charcoals are just carbon in
different form. Under certain temperature and pressure, the
mother-nature took more than 1 billion years for transforming
carbon-bearing materials into clear and shining diamonds. No
wonder most of us  prefer diamonds instead of regular charcoals........

How about the story, cleanig up the ashes of the retort and you discover a small diamond....!!


Comparing the retort with "steel ring kilns"?
judge yourself!:

Making Charcoal - Part One
Making Charcoal - Part Two
Making Charcoal - Part Three

Making Charcoal - Part Four


Or "open pit carbonization" of coconut huks? Quite a smoky thing! (History Tomorrow ~ Coconut Charcoal Making)

One more smoky!! thing at "Mamer Bëschfest 2012, Luxemburg":


The good old VITA retort (Volunteers in Technical Assistance, USA), operated in a kind of wild and rough way:


A lot is spoken these days about "KonTiki" flame curtain carbonization (open pit carbonization).

It means wood and other biomass is added on the top of an open flame. The fire is made in an earth pit or in a large steel vessel (dish). Unfortunately little information is given on these youtube videos about yield and also about productivity (how much charcoal is produced per unit or/and per worker?). The "KonTiki" carbonization is preferably to be used for biochar production as the hot charcoal is quenched by water to cool. Its cumbersome to weight the wet charcoal for purpose of getting the yield on dry mass.


Photo taken from youtube:

"Backyard BioChar Workshop Part 18 of 22 (212) "

or check this video on German language: (Wie befeuert man einen Kon-Tiki?)

Last not Least: please visit FACEBOOK and give a like to make a site more popular for its crowdfounding project in Ghana: search " ankobra farms"(or

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Mobile "adam-retort" ??  I developed a concept, looks great, a prototype was built in end of  2014...    The base of this construction are 2 oil drums, means about 430 litre of volume for biomass. It will be something really new!! Available  on 2 large wheels as an option. And most of the smoke will be burnt and recycled- to heat and dry the wet biomass..... Building costs about ~500€ we assume... --> see extra page 11 on this homepage


and winner of:
Quiet Green Achiever Award for 2013”

Adelaide Hills Natural Resource Centre/ Australia
retort project performed by:  Lisa Brinkley / VEHTEC Pty Ltd


Your want to support a bamboo charcoal project in Ghana!?

and for donations: