Wood pellets

Pellet fuels (or pellets) are biofuels made from compressed organic matter or biomass.^[1] 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.^[2] Wood pellets are the most common type of pellet fuel and are generally made from compacted sawdust^[3] and related industrial wastes from the milling of lumber, manufacture of wood products and furniture, and construction.^[4] Other industrial waste sources include empty fruit bunches, palm kernel shells, coconut shells, and tree tops and branches discarded during logging operations.^[5][6] 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.^[7] 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.^[8] 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.^[9]

Further, their regular geometry and small size allow automatic feeding with very fine calibration. They can be fed to a burner by auger feeding or by pneumatic conveying. Their high density also permits compact storage and transport over long distance. They can be conveniently blown from a tanker to a storage bunker or silo on a customer's premises.^[10]

A broad range of pellet stoves, central heating furnaces, and other heating appliances have been developed and marketed since the mid-1980s.^[11] In 1997 fully automatic wood pellet boilers with similar comfort level as oil and gas boilers became available in Austria.^[12] With the surge in the price of fossil fuels since 2005, the demand for pellet heating has increased in Europe and North America, and a sizable industry is emerging. According to the International Energy Agency Task 40, wood pellet production has more than doubled between 2006 and 2010 to over 14 million tons.^[13] In a 2012 report, the Biomass Energy Resource Center says that it expects wood pellet production in North America to double again in the next five years.

Ref: https://en.wikipedia.org/wiki/Pellet_fuel