The n.1 cause of death of children under five, world-wide, is breathing the smoke from indoor cooking fires.
Charcoal technology helps to reduce this risk.
by Amy Smith
Substances or materials which undergo combustion are called fuels. The most common examples are kerosene, diesel, petrol, charcoal, coal, wood, etc.
A good fuel is one which is readily available, is cheap, burns easily in air and at a moderate rate, has a high calorific value and is environment friendly. There is probably no fuel which can be considered an ideal fuel.
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal andvegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen (see pyrolysis, charand biochar).
It is usually an impure form of carbon as it contains ash; however, sugar charcoal is among the purest forms of carbon readily available, particularly if it is not made by heating but by a dehydration reaction with sulfuric acid to minimise introducing new impurities, as impurities can be removed from the sugar in advance. The resulting soft, brittle, lightweight, black, porous material resembles coal.
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Incomplete burning is what causes the smoke, when raw biomass is used as a fuel.
Incomplete combustion will only occur when there is not enough oxygen to allow the fuel to react completely to produce carbon dioxide and water.
It also happens when the combustion is quenched by a heat sink such as a solid surface or flame trap.
For most fuels, such as diesel oil, coal or wood, pyrolysis occurs before combustion. In incomplete combustion, products of pyrolysis remain unburnt and contaminate the smoke with noxious particulate matter and gases.
Partially oxidized compounds are also a concern; partial oxidation of ethanol can produce harmful acetaldehyde, and carbon can produce toxic carbon monoxide.
The quality of combustion can be improved by design of combustion devices, such as burners and internal combustion engines.
Further improvements are achievable by catalytic after-burning devices (such as catalytic converters) or by the simple partial return of the exhaust gases into the combustion process.
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The gases of indoor cookers kill more than 2 million children per year in the developing world. The engineer Amy Smith of MIT (Massachusetts Institute of Technology) shares a simple but exciting solution: a technology to convert farm waste into charcoal that burns cleanly.
Amy Smith designs cheap, practical fixes for tough problems in developing countries. Among her many accomplishments, the MIT engineer received a MacArthur "genius" grant in 2004 and was the first woman to win the Lemelson-MIT Prize for turning her ideas into inventions. Full bio »