Torrefaction? What’s that?
Torrefaction is a thermo-chemical process that reduces the moisture content of wood and transforms it into a brittle, char-type material. The thermo-chemical process can reduce the mass of wood by 20-30% resulting in a denser, higher-valued product that can be transported more economically than traditional wood chips. Through torrefaction, wood may retain 90% of the energy value. This energy dense end-product can be used as a coal replacement or co-fired/co-milled with coal in electricity generating power plants. Torrefied wood can be used as a soil amendment, for backyard grilling, residential heating, or as a feedstock in gasification processes. This paper is a literature synthesis that will present (1) the torrefaction process, (2) current developments in commercial torrefaction equipment, (3) characteristics of and markets for torrefied wood, and (4) feedstock specifications for torrefaction.