Fresh waste wood from the timber industry is generally used for manufacturing wood pellets: sawdust, offcuts, and untreated recycled wood, etc. Special machines compress the fragments at high pressure; glue or other binding materials are not required. Wood pellets must conform to ONORM and DIN standards. The great advantage of wood pellets is that they are carbon-neutral. In daylight, CO2 is fixed in the tree during growth (photosynthesis). This vegetable matter can then be burned to supply heat. During combustion the same quantity of CO2 is released as was assimilated during photosynthesis. This is why wood is a sustainable fuel.
The market price of granules varies between 85 EUR and 250 EURa tonne. Pellets and briquettes are about the same price; pellets measure between 6 and 12 mm, while briquettes are much larger and are used in manual systems. Pellets are used in automatic combustion systems and develop an output of 4.9 kWh/kg, equivalent to about half a litre of diesel.
The viability of systems fuelled with granules is determined on the one hand by the cost of the investment required, which is higher than for gas-fuelled systems, and on the other by operating costs, which are lower than for conventional systems. According to Valboim, there are about 2,000 plants using wood pellets in Wallonia, and the market share of pellets for heating in Belgium is estimated at 1%. Wood pellets represent an alternative for businesses which can handle the power required. Several studies show that the market for wood-fuelled systems is primarily large buildings, with a heat demand of 50 to 500 kW. At this scale, wood-fuelled boilers are relatively cheap and do not require a large, expensive heating system.
Milieu Direct, Belgium, www.kluwer.be/kluwer/home.asp?doelid=3