Co-Firing in Existing Coal Plants

Grinds Similar to Coal.  Torrefied material grinds similar to coal.   It can be ground in many existing facilities, easing its integration into existing coal facilities.  By comparison, wood pellets are difficult to grind, effectively preventing their use in most existing coal plants without the addition of specially designed grinding and handling equipment.

Burns Similar to Coal. While torrefied wood is a renewable, carbon neutral resource, it burns similar to coal.  Certain volatiles and other compounds (hemi-cellulose material contained in wood) are largely eliminated in the torrefaction process, making torrefied materials easier to co-fire in power plants originally designed to use only coal.  The change in the chemical composition of wood during torrefaction not only increases the energy density, but also improves the manner in which the wood burns in a coal gasifier, permitting more of the energy to be converted into electricity.  This makes the energy content of torrefied wood more valuable.  By comparison, wood pellets contain volatile organic compounds that release smoke when burned.  These volatiles can create slag or ash in existing coal power plants and restrict the use of wood pellets in such plants.