Puuhiili

Puuhiili, commonly referred to as wood charcoal, is a porous, carbon-rich solid produced by pyrolyzing wood in conditions with limited or no oxygen. It differs from coal in its origin, as it is derived from biomass rather than fossil sources, and from activated charcoal through its lower surface area and different porosity.

Production typically involves drying wood and heating it in a kiln, retort, or mound in a controlled, low-oxygen environment. Temperatures generally range from about 400 to 600 degrees Celsius. During slow pyrolysis most volatile compounds are driven off, leaving behind a compact carbon structure. By-products such as tar and combustible gases can be utilized for energy in some setups. Common forms include lump charcoal and briquettes, the latter often incorporating binders or additives to improve shape and burn consistency.

Puuhiili is valued for its high energy density, relatively low moisture, and steady, bright flame. Its porosity affords good heat retention and rapid ignition, making it a popular fuel for cooking, grilling, and space heating. Historically, it also served as a fuel for metalworking forges and other high-heat applications. It is important to distinguish wood charcoal from activated charcoal (aktiivihiili), which is processed for a large internal surface area for filtration rather than combustion.

Environmental considerations emphasize sustainable sourcing of wood and efficient, lower-emission production methods to prevent deforestation and reduce greenhouse gas releases. In modern practice, wood charcoal is often produced from by-products of forestry operations or other biomass residues, aligning with forestry sustainability goals. Safety concerns include indoor air quality and the risk of carbon monoxide with improper use, particularly in enclosed spaces.