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This article deals about the production of charcoal.
This article deals about the '''production of charcoal'''. There are several methods for processing wood residues to make them cleaner and easier to use as well as easier to transport.  Production of charcoal is the most common. 
It is worth mentioning at this point that the conversion of woodfuel to charcoal does not increase the energy content of the fuel - in fact the energy content is decreased.  Charcoal is often produced in rural areas and transported for use in urban areas.  


==Methods==
==Overview==
Charcoal has been made by various methods.  
The pyrolysis temperature appears to be a critical factor determining char yield vs. energy yield (tradeoff). Flexi-pyrolysis units are being developed that can be set for either char yield or gasification yield. Dry biomass can be pyrolyzed at regular atmospheric pressure. For wet biomass, pyrolysis at higher pressure ("supercritical") may be necessary, requiring a more sophisticated technical set-up.  


==Using a clamp==
When large chunks of wood are used as feedstock, the charcoal may need to be crushed before use (beware: coal dust explosion !). Many agrigultural feedstocks and leaf litter will not need to be pulverized but will readily break into smaller pieces by themselves. For information on small-scale gardening, please consult the [http://biochar.pbwiki.com/ Gardening with Biochar FAQ], an excellent resource.
[[File:Charcoal clamp.JPG|thumb|right|350px|A clamp for charcoal production]]
The traditional method in Britain used a clamp. This is essentially a pile of wooden logs (e.g. seasoned oak) leaning against a chimney (logs are placed in a circle). The chimney consists of 4 wooden stakes held up by some rope. The logs are completely covered with soil & straw allowing no air to enter. It has to be lit by introducing some burning fuel into the chimney; the logs burn very slowly (cold fire) and transform into charcoal in a period of 5 days burning. If the soil covering gets torn (cracked) due to the fire, additional soil is placed on the cracks. Once the burn is complete, the chimney is plugged to prevent air to enter.[3]
Modern methods use a sealed metal container, as this does not have to be watched lest fire break through the covering.


==Using charcoal kilns==
==Kilns used==
Several (relatively inexpensive) charcoal kilns can be made which can be used to make charcoal/ See [http://www.biochar-international.org/technology/production the designs at Biochar-international] Most of these require atleast some parts which can not be found in a natural environment (ie metal parts). On the upside however, such parts typically last longer and may be more efficient. Some very simple designs also exist consisting of only a few metal parts (ie 2 barrels), see [http://www.nasa.gov/topics/nasalife/features/biochar.html NASA Langley Research Center's low-tech kiln]
Charcoal can be made using various types of kilns.  


==Why charcoal ?==
==Using traditional kilns==
{{Move|Charcoal}}
[[Image:Biomass3.jpg|thumb|200px|right|Image 1: Traditional Earth Kiln for Charcoal Production]]
An obvious question to ask is why we need charcoal. The answer is that as an energy source, it's more energy dense, and most importantly, the calorific value is higher (heat per weight). This means that a higher temperature can be achieved.  
[[Image:Biomass4.jpg|thumb|200px|right|Image 2: Charcoal Kiln, Kenya ©Heinz Muller/Practical Action]]
[[Image:Biomass5.jpg|thumb|200px|right|Image 3 Improved Charcoal Kiln Found in Brazil, Sudan and Malawi]]
The process can be described by considering the combustion process discussed above. The wood is heated in the absence of sufficient oxygen which means that full combustion does not occur. This allows pyrolysis to take place, driving off the volatile gases and leaving the carbon or charcoal remaining. The removal of the moisture means that the charcoal has a much higher specific energy content than wood.  Other biomass residues such as millet stems or corncobs can also be converted to charcoal.  


This makes has made the fuel more suitable than wood for transport purposes, atleast if it is burned as is (ie for fueling a steam engine). If it was to be compared to ie a [[wood gas]] system, the total amount of energy that can be extracted from charcoal (which is also the original source of charcoal) would without question be lower than that of wood. Perhaps confusing at first glance, this can be explained quite simply: energy is needed to transform wood to charcoal (the first burn (or the "[[pyrolysis]]") will waste a lot of energy. Also, a wood gas system is much more efficient overall (steam engines are only 15% efficient, IC engines are 30% efficient).  
Charcoal is produced in a kiln or pit. A typical traditional earth kiln (see image 1) will comprise the fuel to be carbonised, which is stacked in a pile and covered with a layer of leaves and earth. Once the combustion process is underway the kiln is sealed, and then only once process is complete and cooling has taken place can the charcoal be removed.  


For other tasks as [[blacksmithing]], the firing of material (ie using a [[kiln]], casting, ...) charcoal is the ''only'' natural material that can be used (wood can not be used). Nowadays, blacksmithing is no longer practiced much, and for casting and firing materials, other (non-natural) materials are being used instead (usually as it allows to better control the temperature, use more efficient kiln/forge designs, ...)
A simple improvement to the traditional kiln is also shown in image 3. A chimney and air ducts have been introduced which allow for a sophisticated gas and heat circulation system and with very little capital investment a significant increase in yield is achieved.  


[[File:Homemade waterfilter.jpg|thumb|right|350px|Using charcoal as a filter]]
==Using a clamp==
Other, more useful purposes of charcoal (from a AT-standpoint) are of a different kind. Water for example can be filtered by means of charcoal. In developed countries, activated charcoal is mostly used rather than regular charcoal, but charcoal can also be used (although it is less efficient).
The traditional method in Britain used a clamp which is itself already a relatively advanced yet locally-constructable kiln. This is essentially a pile of wooden logs (e.g. seasoned oak) leaning against a chimney (logs are placed in a circle). The chimney consists of 4 wooden stakes held up by some rope. The logs are completely covered with soil & straw allowing no air to enter. It has to be lit by introducing some burning fuel into the chimney; the logs burn very slowly (cold fire) and transform into charcoal in a period of 5 days burning. If the soil covering gets torn (cracked) due to the fire, additional soil is placed on the cracks. Once the burn is complete, the chimney is plugged to prevent air to enter.[3]
Modern methods use a sealed metal container, as this does not have to be watched lest fire break through the covering.
 
==Using charcoal kilns==
[[File:Charcoal_kiln.png|thumb|right|200px|DIY charcoal kiln made from oil drum]]
Several (relatively inexpensive) charcoal kilns can be made which can be used to make charcoal/ See [http://www.biochar-international.org/technology/production the designs at Biochar-international page 1] and [http://www.biochar-international.org/technology/stoves page 2] Most of these require at least some parts which can not be found in a natural environment (ie metal parts). On the upside however, such parts typically last longer and may be more efficient. Some very simple designs also exist consisting of only a few metal parts (ie 2 barrels), see [http://www.nasa.gov/topics/nasalife/features/biochar.html NASA Langley Research Center's low-tech kiln]


==See also==
==See also==
* [[Wood]]
* [[Wood]]
* [[Charcoal]]/Biochar
* [[Charcoal]]/[[Biochar]]
* [[Charcoal Making for Small Scale Enterprises]]
* [[Charcoal Making for Small Scale Enterprises]]
* [[Blackpowder]]
* [[Blackpowder]]
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* http://www.wikihow.com/Make-Charcoal
* http://www.wikihow.com/Make-Charcoal
* http://www.instructables.com/id/How-to-Make-some-Charcoal/
* http://www.instructables.com/id/How-to-Make-some-Charcoal/
* [http://vignette3.wikia.nocookie.net/solarcooking/images/e/ef/Traditional_Charcoal_in_Africa_and_need_of_African_Institutes_ARTIS.pdf Traditional Charcoal in Africa and need of African Institutes]


[[Category:Charcoal]]
[[Category:Charcoal]]
[[Category:Energy storage]]

Revision as of 18:39, 2 July 2016

This article deals about the production of charcoal. There are several methods for processing wood residues to make them cleaner and easier to use as well as easier to transport. Production of charcoal is the most common.

It is worth mentioning at this point that the conversion of woodfuel to charcoal does not increase the energy content of the fuel - in fact the energy content is decreased. Charcoal is often produced in rural areas and transported for use in urban areas.

Overview

The pyrolysis temperature appears to be a critical factor determining char yield vs. energy yield (tradeoff). Flexi-pyrolysis units are being developed that can be set for either char yield or gasification yield. Dry biomass can be pyrolyzed at regular atmospheric pressure. For wet biomass, pyrolysis at higher pressure ("supercritical") may be necessary, requiring a more sophisticated technical set-up.

When large chunks of wood are used as feedstock, the charcoal may need to be crushed before use (beware: coal dust explosion !). Many agrigultural feedstocks and leaf litter will not need to be pulverized but will readily break into smaller pieces by themselves. For information on small-scale gardening, please consult the Gardening with Biochar FAQ, an excellent resource.

Kilns used

Charcoal can be made using various types of kilns.

Using traditional kilns

Image 1: Traditional Earth Kiln for Charcoal Production
Image 2: Charcoal Kiln, Kenya ©Heinz Muller/Practical Action
Image 3 Improved Charcoal Kiln Found in Brazil, Sudan and Malawi

The process can be described by considering the combustion process discussed above. The wood is heated in the absence of sufficient oxygen which means that full combustion does not occur. This allows pyrolysis to take place, driving off the volatile gases and leaving the carbon or charcoal remaining. The removal of the moisture means that the charcoal has a much higher specific energy content than wood. Other biomass residues such as millet stems or corncobs can also be converted to charcoal.

Charcoal is produced in a kiln or pit. A typical traditional earth kiln (see image 1) will comprise the fuel to be carbonised, which is stacked in a pile and covered with a layer of leaves and earth. Once the combustion process is underway the kiln is sealed, and then only once process is complete and cooling has taken place can the charcoal be removed.

A simple improvement to the traditional kiln is also shown in image 3. A chimney and air ducts have been introduced which allow for a sophisticated gas and heat circulation system and with very little capital investment a significant increase in yield is achieved.

Using a clamp

The traditional method in Britain used a clamp which is itself already a relatively advanced yet locally-constructable kiln. This is essentially a pile of wooden logs (e.g. seasoned oak) leaning against a chimney (logs are placed in a circle). The chimney consists of 4 wooden stakes held up by some rope. The logs are completely covered with soil & straw allowing no air to enter. It has to be lit by introducing some burning fuel into the chimney; the logs burn very slowly (cold fire) and transform into charcoal in a period of 5 days burning. If the soil covering gets torn (cracked) due to the fire, additional soil is placed on the cracks. Once the burn is complete, the chimney is plugged to prevent air to enter.[3] Modern methods use a sealed metal container, as this does not have to be watched lest fire break through the covering.

Using charcoal kilns

DIY charcoal kiln made from oil drum

Several (relatively inexpensive) charcoal kilns can be made which can be used to make charcoal/ See the designs at Biochar-international page 1 and page 2 Most of these require at least some parts which can not be found in a natural environment (ie metal parts). On the upside however, such parts typically last longer and may be more efficient. Some very simple designs also exist consisting of only a few metal parts (ie 2 barrels), see NASA Langley Research Center's low-tech kiln

See also

External links

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