Figure 1. Potential energy curves for a reaction proceeding homogenously (full curve) or on a surface (dotted line).

Charcoal is perhaps the oldest known fuel, having been found in archeological sites dating as far back as the Pleistocene era. Charcoal is a relatively smokeless and odorless fuel, and thus ideal for cooking and heating.

History

As humans entered the Bronze Age, charcoal was the only material that could simultaneously heat and reduce metallic ores. Later, the addition of an air blower made it possible to achieve temperatures high enough to soften or melt iron. During the Industrial Revolution, charcoal was largely displaced in most ironworks by coke derived from coal. However in Brazil, which lacks adequate coking coal resources, most of the charcoal produced is still used to reduce iron ore.

Charcoal was produced in pits, and later in kilns, by burning wood with air insufficient for complete combustion...