The main wood fuel types are logs, wood chips and pellets. Briquettes are also available for wood burning stoves. Compare the calorific values of different fuel types on the Biomass Energy Centre website.
Woodfuel generally comes from forest management, harvesting, tree-surgery and pruning operations. Other sources being developed include: energy forestry, waste wood from construction and manufacturing, and timber processing residues and co-products. Increasingly, undermanaged woodlands on farms and estates are becoming a valuable source of woodfuel.
Logs are ideal for domestic, community, farm and estate installations using stoves or boilers. Stoves require frequent stoking whereas boilers, particularly large ones, only need to be fuelled once or twice a day. Firewood should be dry and seasoned by the supplier for one or two years.
Wood chips are widely used by businesses, communities and public sector organisations to generate heat. Being a relatively bulky fuel to transport, they are ideal for meeting local heat demand. They can be processed to meet the requirements of a wide variety of systems.
Pellets are made from compressed wood by-products (e.g. sawdust). They are much less bulky than wood chips, and so need less storage space, are easier to handle and can be cheaper to transport. They can be used in both stoves and boilers.