Pellet fuels (or
pellets) are
biofuels made from compressed organic matter or biomass. Pellets can be made from any one of five general categories of biomass: industrial waste and co-products,
food waste,
agricultural residues,
energy crops, and virgin
lumber.
Wood pellets are the most common type of pellet fuel and are generally made from compacted
sawdust and related industrial wastes from the
milling of lumber, manufacture of
wood products and
furniture, and
construction. Other industrial waste sources include empty fruit bunches,
palm kernel shells,
coconut shells, and tree tops and branches discarded during
logging operations. So-called "black pellets" are made of
biomass, refined to resemble hard
coal and were developed to be used in existing coal-fired
power plants. Pellets are categorized by their
heating value,
moisture and
ash content, and dimensions. They can be used as fuels for power generation, commercial or residential heating, and
cooking. Pellets are extremely dense and can be produced with a low moisture content (below 10%) that allows them to be burned with a very high combustion
efficiency.