Fuel wood is used as fuel. The burning of wood is currently the largest use of energy derived from a solid fuel biomass. Fuel wood can be used for cooking and heating, and occasionally for fueling steam engines and steam turbines that generate electricity. Fuel wood may be available as Fuel wood (e.g. logs, bolts, blocks), charcoal, chips, sheets, pellets and sawdust. The particular form used depends upon factors such as source, quantity, quality and application. Sawmill waste and construction industry by-products also include various forms of lumber tailings.