A charcoal pile or charcoal clamp is a carefully arranged pile of

wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin th ...

, covered by turf or other layer, inside which a fire is lit in order to produce

charcoal Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, cal ...

. The pile is tended by a

charcoal burner A charcoal burner is someone whose occupation is to manufacture charcoal. Traditionally this is achieved by carbonising wood in a charcoal pile or kiln. Charcoal burning is one of the oldest human crafts. The knowledge gained from this industr ...

. It is similar to a charcoal kiln, but the latter is usually a permanent structure made of materials such as stone.

History

Since antiquity, charcoal piles have been used to make

. Charcoal is much lighter than natural

timber Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, wi ...

and therefore easier to transport. In addition, charcoal generates much more heat. Charcoal production was therefore an important part of the

economy An economy is an area of the production, distribution and trade, as well as consumption of goods and services. In general, it is defined as a social domain that emphasize the practices, discourses, and material expressions associated with the ...

in early modern times. At that time, charcoal was the only fuel that could generate the heat necessary for

iron smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a c ...

. In the late 18th century, it is recorded that the duties of a master coalman at an

ironworks An ironworks or iron works is an industrial plant where iron is smelted and where heavy iron and steel products are made. The term is both singular and plural, i.e. the singular of ''ironworks'' is ''ironworks''. Ironworks succeeded bloomeri ...

were not only to ensure the supply of charcoal and to supervise charcoal burners and their assistants, but also to visit frequently the charcoal clearings (''Kohlhäue'') i.e. those parts of the forest used to produce charcoal. In 1713, a process was invented for producing coke suitable for blast furnaces from

hard coal Anthracite, also known as hard coal, and black coal, is a hard, compact variety of coal that has a submetallic luster. It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the high ...

(stone coal). From then on, the consumption of the more expensive charcoal decreased steadily despite increasing iron production. From the 17th century onwards, pitch furnaces were increasingly used and in the 19th century retorts were also employed. As a result, fewer and fewer charcoal piles were used. The gradual decline of charcoal began in the 19th century, when hard coal practically replaced charcoal and later also town gas and electricity became more important. The

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

triggered a strong demand for charcoal again. At that time,

motor vehicle A motor vehicle, also known as motorized vehicle or automotive vehicle, is a self-propelled land vehicle, commonly wheeled, that does not operate on Track (rail transport), rails (such as trains or trams) and is used for the transportation of pe ...

s were also powered by wood or charcoal. Today it is of no particular economic importance, in particular due to the loss of

wood gas Wood gas is a fuel gas that can be used for furnaces, stoves, and vehicles. During the production process, biomass or related carbon-containing materials are gasified within the oxygen-limited environment of a wood gas generator to produce a c ...

es during charcoal production, the

calorific value The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it. The ''calorific value'' is the total energy rele ...

yield from wood is extremely low. Charcoal burning is still used only for traditional reasons and for some special applications of charcoal.

Operation

In order to produce charcoal, water and the volatile components of the wood have to

evaporate Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...

. At the charcoal burning site, which is located where possible near a body of water so that it can be extinguished later, the wood pile is built in approximately

hemispherical A sphere () is a Geometry, geometrical object that is a solid geometry, three-dimensional analogue to a two-dimensional circle. A sphere is the Locus (mathematics), set of points that are all at the same distance from a given point in three ...

or conical piles, using short logs, mostly one-metre long, in even fashion (standing or lying down), around the central chimney (''Quandel''). A bank of ash and earth (''Stübbewall'') can be built all round the pile. On top of this an airtight roof is constructed of dry fir branches, leaves, hay or straw, or alternatively of

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...

, vegetation and

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...

. Finally the pile is sealed airtight with a mix of ash and charcoal pieces (possibly known as 'culm' or 'brusque'; German: ''Lösche, Stübbe, Stibbe'' or ''Gestübe'') and earth, with the exception of the central chimney. A support made of logs and planks is then built round the base of the pile. Then the pile is ignited via the chimney which is then also sealed. A sure sign that the charring has started is the so-called 'knocking' of the pile. The strong heating leads to

deflagration Deflagration (Lat: ''de + flagrare'', "to burn down") is subsonic combustion in which a pre-mixed flame propagates through a mixture of fuel and oxidizer. Deflagrations can only occur in pre-mixed fuels. Most fires found in daily life are diffu ...

which, if the covering of the pile is too strong, to an

explosion An explosion is a rapid expansion in volume associated with an extreme outward release of energy, usually with the generation of high temperatures and release of high-pressure gases. Supersonic explosions created by high explosives are known ...

. At the top as well as at the foot of the pile, individual holes are made in the surface, by means of which the fire in the pile is regulated. Under this blanket, incineration is conducted with carefully regulated air access in such a way that, if possible, no more wood burns than is absolutely necessary to heat the entire wood mass to the charring temperature. The wood must char, not burn, inside the pile; air being let in through the small holes so that no fire can start. But it creates a lot of heat and the water evaporates, tar condenses on the green roof, the smoke is yellowish-white and odourless. The heat of the smouldering wood inside the pile drives all liquid and organic components out of the wood as smoke. The job of the

at this stage is to neither let the pile go out nor to let it burn down as a result of too much air over the following days or weeks (depending on the size of the pile and the weather). To do this, he drills and closes the air holes. Essentially, only the gases and vapours that develop from the heated wood should burn. By observing the smoke and its colour, the charcoal burner knows whether there is too much or too little air. The colour of the smoke that escapes indicates whether charring is complete. If the smoke is white and dense, the wood is not yet charred. If it is light, almost transparent and slightly bluish, the wood is charred. The air holes are now moved further down in order to also draw the fire into the lower areas of the kiln. Each time the draft holes are moved, the smoke colour changes, the kiln charred from top to bottom. As the charring progresses, the kiln slowly sinks in. Once charring is complete, the fire in the pile is quickly extinguished by the clogging of the air holes. (PDF; 1.25 MB), at 750jahrewolfwil.ch, retrieved 14 August 2016. and the pile slowly begins to cool down. For better sealing the pile is often sprinkled with water and compacted with a wooden hammer. The pile has now shrunk to about half its original volume. Now the cover is opened and then the coal is pulled out with a rake, fork or shovel and spread out to cool down. Embers are extinguished with water or smothered with ash. If this is not done properly, the charcoal that has been produced burns within a very short time under great heat (

exothermic reaction In thermochemistry, an exothermic reaction is a "reaction for which the overall standard enthalpy change Δ''H''⚬ is negative." Exothermic reactions usually release heat. The term is often confused with exergonic reaction, which IUPAC defines ...

). The heat generated in this process is so great that it is impossible to approach the pile. The coal must now cool down for at least 12 hours. If the charcoal is too small it remains in the pile and is mixed with the ash. Only the carbon skeleton of the wood cells remains but this is still 98% of the wood. From 100 kg of hardwood, approximately 30 kg of charcoal can be obtained. During charcoal production, by-products are generated such as

wood tar Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. "a dark brown or black bi ...

wood vinegar Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin t ...

, wood spirit and wood gas. These cannot be fully utilised in the pile. If tar extraction was to be combined with the charring of the pile, small pits were made in the ground or the ground was lined with clay and the tar led out of the pile by means of a channel, and the wood vinegar was treated with

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

. Pipes led into a

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...

Dieter Osteroth: ''Biomasse: Rückkehr zum ökologischen Gleichgewicht.'' Biomass: Return to Ecological Balance.Springer, 1992, , p. 88. or wall-supported piles were built on sloping ground.

Gallery

Meiler 1.JPG, Heart (Kern or Quandel) of the charcoal pile on an old Meilerplatz Meiler 3.JPG, Layer of beech wood around the heart Meiler 5.JPG, Pile with various layers (wood, spruce brushwood (Fichtenreisig), grass sods) Kohlenmeiler_in_Waldmünchen_(2014).jpg, Lighting of a charcoal pile by honorary guests at a ''Meilerfest'' (2014) Meiler 10.JPG, Covered with loam, ready for firing Meiler 11.JPG, Finished pile with windbreak, charcoal burner’s hut and fireplace Kohlenmeiler Hagen 2004.jpg, Charcoal pile in the Westphalian Open Air Museum, Hagen SI Netphen-Walpersdorf Kohlenmeiler 01.jpg, Charcoal pile in Walpersdorf, one of the last in the Siegerland Walhauser-kohlenmeiler-ernte.jpg, Opening of the charcoal pile Walhauser-holzkohle.jpg, Charcoal product Köhler JH-Wende.JPG, Charcoal burners at work (turn of the 19th/20th centuries) Meule charbon bois.jpg, Section of a charcoal pile File:Kullaa.vaakuna.svg, A red charcoal pile in the coat of arms of Kullaa

References

Literature

* Karl Hasel, Ekkehard Schwartz: ''Forstgeschichte. Ein Grundriss für Studium und Praxis''. 2., aktualisierte Auflage. Kessel, Remagen, 2002, * Richard B. Hilf: ''Der Wald. Wald und Weidwerk in Geschichte und Gegenwart – Erster Teil''

eprint In academic publishing, an eprint or e-print is a digital version of a research document (usually a journal article, but could also be a thesis, conference paper, book chapter, or a book) that is accessible online, usually as green open access, w ...

Aula, Wiebelsheim, 2003, * Hildebrandt, H., Heuser-Hildebrandt, B. and Stumböck, M.(2001): Bestandsgeschichtliche und kulturlandschaftsgenetische Untersuchungen im Naturwaldreservat Stelzenbach, Forstamt Nassau, Revier Winden. Mainzer Naturwissenschaftliches Archiv, Beiheft 25, 83 S., Mainz. * . A continuation of the general forestry magazine. Part One.

External links

European Charcoal Burners' Society

Charcoal burner's festival (''Köhlerfest'') in Fischbach/Kreis Kaiserslautern

Annual charcoal burner's festival in Glasofen
in the

Spessart Spessart is a ''Mittelgebirge'', a range of low wooded mountains, in the States of Bavaria and Hesse in Germany. It is bordered by the Vogelsberg, Rhön and Odenwald. The highest elevation is the Geiersberg at 586 metres above sea level. Etymo ...