question: Why is burned wood (charcoal) such a good fuel? Wouldn't using unburned wood be better?
comment: Charcoal isnt burned wood, it has been heated so that all the liquuid is removed. It is created by heating up wood so that it is hot as fire, but without oxygen so it never actually burned.
passages: Section::::Historical development.
  
  Wood has been used as fuel for millennia. Historically, it was limited in use only by the distribution of technology required to make a spark. Heat derived from wood is still common throughout much of the world. Early examples included a fire constructed inside a tent. Fires were constructed on the ground, and a smoke hole in the top of the tent allowed the smoke to escape by convection.
   The advantage of burning charcoal compared to burning wood is the absence of water and other components. This allows charcoal to burn at higher temperatures, and give off very little smoke (regular wood gives off a good amount of steam, organic volatiles, and unburnt carbon particles — soot — in its smoke).
  
  Section::::History.
   Slow combustion stoves increase efficiency of wood heaters burning logs, but also increase particulate production. Low pollution/slow combustion stoves are a current area of research. An alternative approach is to use pyrolysis to produce several useful biochemical byproducts, and clean burning charcoal, or to burn fuel extremely quickly inside a large thermal mass, such as a masonry heater. This has the effect of allowing the fuel to burn completely without producing particulates while maintaining the efficiency of the system.
   Section::::Applications.:Cooking.
  
  There is a correlation between density and calories/volume. This makes the denser hardwoods like oak, cherry, and apple more suited for camp fires, cooking fires, and smoking meat, as they tend to burn hotter and longer than softwoods like pine or cedar whose low-density construction and highly-flammable sap make them burn quickly and without producing quite as much heat.
  
  Section::::See also.
  
  BULLET::::- List of woods
  
  BULLET::::- Hardwood flooring
  
  BULLET::::- Softwood
  
  BULLET::::- Janka hardness test
  
  BULLET::::- Brinell scale
  
  Section::::Further reading.
   The discovery of how to make fire for the purpose of burning wood is regarded as one of humanity's most important advances. The use of wood as a fuel source for heating is much older than civilization and is assumed to have been used by Neanderthals. Today, burning of wood is the largest use of energy derived from a solid fuel biomass. Wood fuel can be used for cooking and heating, and occasionally for fueling steam engines and steam turbines that generate electricity. Wood may be used indoors in a furnace, stove, or fireplace, or outdoors in furnace, campfire, or bonfire.
   The environmental impact of using wood as a fuel depends on how it is burnt. Higher temperatures result in more complete combustion and less noxious gases as a result of pyrolysis. Some may regard the burning of wood from a sustainable source as carbon-neutral. A tree, over the course of its lifetime, absorbs as much carbon (or carbon dioxide) as it releases when burnt.
   Section::::Fireplaces and stoves.
  
  The development of the chimney and the fireplace allowed for more effective exhaustion of the smoke. Masonry heaters or stoves went a step further by capturing much of the heat of the fire and exhaust in a large thermal mass, becoming much more efficient than a fireplace alone.
   Since the Iron Age, high temperatures have had to be produced for iron smelting, for glassmaking and for the working of precious metals. Charcoal has been used to do this for centuries and, in order to produce it, entire forests were felled. With the increasing use of stone coal from the 18th century, the charcoal burning industry declined.
   The first known use of fuel was the combustion of wood or sticks by "Homo erectus" nearly two million years ago. Throughout most of human history fuels derived from plants or animal fat were only used by humans. Charcoal, a wood derivative, has been used since at least 6,000 BCE for melting metals. It was only supplanted by coke, derived from coal, as European forests started to become depleted around the 18th century. Charcoal briquettes are now commonly used as a fuel for barbecue cooking.
   There are now a number of wood and wax firelogs made using renewable materials. These are made using plant or animal based renewable waxes such as palm oil. These logs can be considered to be carbon neutral firelogs during combustion as the carbon released on combustion is the same carbon absorbed when the plants are growing.
  
  Sulphur emissions are virtually eliminated with renewable firelogs as they do not contain paraffin waxes.
  
  Section::::Types.:Marketing.
   Not all hardwoods have a higher potential energy content than all softwoods. Wood varies by species and even individual trees (a tree with many years of slow growth will have a higher BTU content than a tree of the same species and same size than a tree with a few years of rapid growth). Osage orange, also known as hedge, is perhaps the highest-BTU wood that is common in North America.
   According to "The Bioenergy Knowledge Centre", the energy content of wood is more closely related to its moisture content than its species. The energy content improves as moisture content decreases.
  
  In 2008, wood for fuel cost $15.15 per 1 million BTUs (0.041 EUR per kWh).
  
  Section::::Environmental impacts.
  
  Section::::Environmental impacts.:Combustion by-products.
  
  As with any fire, burning wood fuel creates numerous by-products, some of which may be useful (heat and steam), and others that are undesirable, irritating or dangerous.
   The growth in popularity of wood heat also led to the development and marketing of a greater variety of equipment for cutting, splitting and processing firewood. Consumer grade hydraulic log splitters were developed to be powered by electricity, gasoline, or PTO of farm tractors. In 1987 the US Department of Agriculture published a method for producing kiln dried firewood, on the basis that better heat output and increased combustion efficiency can be achieved with logs containing lower moisture content.
  
  The magazine "Wood Burning Quarterly" was published for several years before changing its name to "Home Energy Digest" and, subsequently, disappearing.
   Exhaust gas emission from an internal combustion engine is significantly lower on wood gas than on petrol. Especially the hydrocarbon emissions are low on wood gas. A normal catalytic converter works well with wood gas, but even without it, emission levels less than 20 ppm HC and 0.2% CO can be easily achieved by most automobile engines. Combustion of wood gas generates no particulates, and the gas renders thus very little carbon black amongst motor oil.
  
  Section::::Usage.:Stoves, cooking and furnaces.
   One advantage of wood briquettes is that they have a lower ash and sulfur content, compared to fossil fuels. The carbon dioxide (CO) balance is even, because wood briquettes release just as much CO to the atmosphere as the trees used for their production once absorbed through growth by photosynthesis. In addition, briquettes have a substantially higher energy content per cubic foot due to their density which means less storage space and more heat released per lb.
  
  Section::::Energy content.
   Section::::In popular culture.
  
  The last section of the film "Le Quattro Volte" (2010) gives a good and long, if poetic, documentation of the traditional method of making charcoal. The Arthur Ransome children's series "Swallows and Amazons" (particularly the second book, "Swallowdale") features carefully drawn vignettes of the lives and the techniques of charcoal burners at the start of the 20th century, in the Lake District of the UK.
  
  Section::::See also.
  
  BULLET::::- Binchōtan
  
  BULLET::::- Biochar
  
  BULLET::::- Biomass briquettes
  
  BULLET::::- Charcoal in food
  
  BULLET::::- Char
  
  BULLET::::- Char cloth
  
  BULLET::::- Coke (fuel), made from coal rather than wood
  
  BULLET::::- Pyrolysis
  
  BULLET::::- Shichirin
   Charcoal can be made by slow pyrolysis of wood by heating it in the absence of air in a kiln. The carefully stacked branches, often oak, are burned with a very limited amount of air. The process of converting them into charcoal takes about fifteen hours. Charcoal is used as a fuel in barbecues and by blacksmiths and has many industrial and other uses.
   In contrast to civilizations in relatively arid regions (such as Mesopotamia and Egypt), the Greeks, Romans, Celts, Britons, and Gauls all had access to forests suitable for using as fuel. Over the centuries there was a partial deforestation of climax forests and the evolution of the remainder to coppice with standards woodland as the primary source of wood fuel. These woodlands involved a continuous cycle of new stems harvested from old stumps, on rotations between seven and thirty years. One of the earliest printed books on woodland management, in English, was John Evelyn's "Sylva, or a discourse on forest trees" (1664) advising landowners on the proper management of forest estates. H. L. Edlin, in "Woodland Crafts in Britain", 1949 outlines the extraordinary techniques employed, and range of wood products that have been produced from these managed forests since pre-Roman times. And throughout this time the preferred form of wood fuel was the branches of cut coppice stems bundled into faggots. Larger, bent or deformed stems that were of no other use to the woodland craftsmen were converted to charcoal.
   Wood smoke can be used to preserve food. In the hot smoking process the food is exposed to smoke and heat in a controlled environment. The food is ready to eat when the process is complete, having been tenderised and flavoured by the smoke it has absorbed. In the cold process, the temperature is not allowed to rise above . The flavour of the food is enhanced but raw food requires further cooking. If it is to be preserved, meat should be cured before cold smoking.
  
  Section::::Uses.:Timber.
   BULLET::::- Extruded charcoal is made by extruding either raw ground wood or carbonized wood into logs without the use of a binder. The heat and pressure of the extruding process hold the charcoal together. If the extrusion is made from raw wood material, the extruded logs are subsequently carbonized.
  
  Section::::Uses.
   Section::::Uses.:Metallurgical fuel.
  
  Charcoal burns at temperatures exceeding . By comparison the melting point of iron is approximately . Due to its porosity, it is sensitive to the flow of air and the heat generated can be moderated by controlling the air flow to the fire. For this reason charcoal is still widely used by blacksmiths. Charcoal has been used for the production of iron since Roman times and steel in modern times where it also provided the necessary carbon. Charcoal briquettes can burn up to approximately with a forced air blower forge.
   The original fuel for forge fires was charcoal. Coal did not begin to replace charcoal until the forests of first Britain (during the AD 17th century), and then the eastern United States of America (during the 19th century) were largely depleted. Coal "can be" an inferior fuel for blacksmithing, because much of the world's coal is contaminated with sulfur. Sulfur contamination of iron and steel make them "red short", so that at red heat they become "crumbly" instead of "plastic". Coal sold and purchased for blacksmithing should be largely free of sulfur.
   There are a variety of designs to choose from in building a campfire. A functional design is very important in the early stages of a fire. Most of them make no mention of fuelwood—in most designs, fuelwood is never placed on a fire until the kindling is burning strongly.
   Many softwoods will season (dry) much more quickly than many hardwoods. For example, pine that has been cut, split, stacked and topcovered will usually be ready to burn in one year; oak may be expected to take three years under the same conditions.
  
  Section::::Fuel.:Hardwood or softwood.:Softwood mythology.
   Section::::Uses.:Fuel.
  
  Wood has traditionally been used for fuel, especially in rural areas. In less developed nations it may be the only fuel available and collecting firewood is often a time consuming task as it becomes necessary to travel further and further afield in the search for fuel. It is often burned inefficiently on an open fire. In more developed countries other fuels are available and burning wood is a choice rather than a necessity. Modern wood-burning stoves are very fuel efficient and new products such as wood pellets are available to burn.
  
presuppositions: Charcoal is burned wood. Charcoal is burned wood.
corrections: Charcoal is not burned wood as it has been heated so that all the liquid is removed. Charcoal is wood that is heated so that all the liquid is removed.
raw_presuppositions: Charcoal is burned wood. Charcoal is burned wood.
raw_corrections: Charcoal is not burned wood as it has been heated so that all the liquid is removed. Charcoal is wood that is heated so that all the liquid is removed.