adam + partner appropriate technology
adam + partnerappropriate technology

Coffee Husks Carbonization

Latest News 2022,

i developed 4 concepts for a
low-cost carbonization of coffee husks! and other bio mass like nuts, rice husks, maize cops,
water hyacinths, olive kernels, etc.

First 1) the    "Open Pit Drum System"

It works with a chimney a bottom plate and removable oil drums. Its operation is simple and continuously. It can be seen in the middle of the photo, behind of me standing there. This carbonizer works well.


On the right side of the photo, you see the Drum Retort Carbonizer.

This work was done for CARiTAS-ETHiOPiA in the Bale Mountains.

The 2nd System for low-cost carbonization of coffee husks (and similar biomass  like nuts, etc.) is the
Drum-Retort Carbonizer. Harmful wood gas emissions (methane etc.) are completely and safely burned below the oil drum and its heat used to push the carbonization. (see photo on the left side).

This carbonizer works well. The outer shell of the carbonizer is insulated.


About 19,5 kg of sun dry coffee husks fit into the volume of about 193 liters. 

(210liter -15l top left with air space 5cm, -tubes 3,4l -3,4l ), V = 3,14 * r² * h; 3,14 * 0,035*0,035 *0,88m  (1m³ =  ~101 kg).

If filled with rice husks (1m³ ~100kg) we may receive similar results.


About 7 kg of coffee husks char can be harvested.

About ~2 kg of waste wood is burned for initializing the process.


Efficiency: 19,5kg --> 7kg,      follows 100kg --> 36kg  

means ~36% Efficiency, (however ~2kg of waste wood burnt not counted)


The 3rd System is a
"Rotary Drum Carbonizer".

An exchangeable oil drum is rotated by hand or by some electric device and the biomass carbonized. The wood gas is cleanly burned, and the available heat used to push carbonization.


We did not build it yet, but drawings are available. It is expected to produce a very even carbonized biomass.


The 4th System will be a
Shelter Drum Retort Carbonizer    (Shelter Drum Retort Kiln)

this is the most promising one.
We successfully built a prototype in Kenya in Jan. 2024


So the Shelter Drum Retort Kiln will considerably use little or less wood for

pre-heating compared to other methods.


So the Shelter Drum Retort  Kiln will be with a closed lid on the top, no opening at the top of the barrel at all (also saving considerable cost for manufacturing).
So the Shelter Drum Retort Kiln will work with a standard oil drum, about 210 liters. A village standard workshop without sophistication will be enough to undertake the small modifications needed on the drums.
So the Shelter Drum Retort Kiln will work without this ceramic wool which is needed for the Retort Drum Kiln, but it has a well insulated overall structure.
So the Shelter Drum Retort Kiln will have a much larger surface for heat transfer compared to the Retort Drum Kiln
Also, it would use retained heat from the shelter structure from the previous batch when you start a 2nd batch. So a high efficiency can be expected of about 28%.
So the Shelter Drum Retort Kiln will be cheaper on a long term compared to a Retort Drum Kiln- as it uses standard oil drums with only minimal modifications made on them and a brick shelter which only needs to be built once (mason work for one day).
The batches can be produced continuously without waiting for cooling in the shelter- that means if you have e.g. 5 oil drums with a burning cycle of about 2 hours each, one person can fill/carbonize 5 times à 210 liters that means:
= 1050 liters of biomass (water hyacinths for instance) during about 10 working hours.

So the Shelter Drum Retort Kiln will have a possibility to watch and see the burning of the wood gas directly. This will help to determine when the carbonization cycle and batch will be finished.


About a 500 € investment can be assumed under these conditions:
2 shelters are built (150 + 150 = 300€?) from bricks and a set of 10 oil-drums (barrels, 10 x 20€ = 200€?) is needed. 2 workers are engaged. By this, ~10 barrels filled with biomass can be carbonized in 10 hours. 10 x 60kg = 600kg (wood, oven dry e.g.) which will give about 10 x 17kg = 170kg of charcoal. This under the assumption of
a 2 hours batch time.

In the case of a 1,5 hours batch time, the amount would increase to 900kg of wood used and 255kg of charcoal produced.


Photo showing the clean burning of wood gas (smoke) in the Shelter Drum Retort Kiln



Briquetting Factory, facts and information:

This site is still under construction,


but look under  page 5    1st:    CCS (Continuous Carboniztation System).



Youtube video. "Charbon oublié (french) shows an interesting briquetting plant in Haiti. They are using charcoal left over (dust) for briquetting, but the charcoal can also be provided by a retort carbonization.


A similar production was set up by

in Kenya     (India)

What is Briquetting Plant

Briquetting plant is an eco friendly technology to convert diverse residues like forestry, industrial and agriculture waste into solid blocks of bio-fuel. Cylindrical shaped briquettes are made with high mechanical pressure using binder less technology. Hence no need for any binder or chemical. Bio-briquettes are substitute to non renewable fossil fuels and can be used in several manufacturing industries like kilns, furnaces and boilers. Ecological bio-briquettes are pollution free and also contribute to greener surroundings which save worthy foreign exchange. The motto behind bio-briquettes is Wealth from Waste. Briquetting plant converts agriculture residues into solid bio-fuel. For farmers to earn money from waste, briquetting press is the promising substitute for green energy production. The model "JUMBO-90" works on the famous concept of binder less technology.    (India)

Biomass Briquetting Machine, Watch Briquetting Machine video - IDI EXIM, Coimbatore, India.


Real Tech Engineering


Piston Press


Piston Press


Sree Engineering Works (India)


90mm briquette plant for biomass

Roller Press from China


If you are intersted in the briquette press machine, please contact: +86 15838193807
Email: Skype: dongfang2012815


coal briquette press, roller press machine,briquetting press, coal pelletizer

15TPH coal briquette production line/ coal briquettes belt dryer


This 15TPH coal briquette production line is builded in Beijing. If u are interested in, please feel free to contact me.
Contact information: Alanna.Liu
Cellphone No.: +08613849119469

JReal Briquetagem


Mec.Ind. JReal.Brazil: (31) 3364-5501    


Prensa Briquetadeira (25 á 30 ton).wmv


Prensa Briquetadeira .mp4



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