Forestry and wood processing residues are a potentially significant source of bio-energy fuels. For a variety of reasons storage of these materials prior to utilisation is often necessary. The storage of comminuted (chipped, hogged, shredded or reduced to small particle size by other means (sawing or sanding)) biomass, particularly fresh (green) material such as logging residues can lead to degradation of the fuel due to biological and thermo-chemical processes.