what is biomass fuel?

Biomass pellets are produced by compressing the material,

which has first passed through a hammer mill to provide a uniform dough-like mass.This mass is fed to a press where it is squeezed through a die having holes of the size required (normally 6 mm diameter, sometimes 8 mm or larger). The high pressure of the press causes the temperature of the wood to increase greatly,

and the ligninplasticizes slightly forming a natural "glue" that holds the pellet together as it cool.