<P> Solid fuel refers to various forms of solid material that can be burnt to release energy, providing heat and light through the process of combustion . Solid fuels can be contrasted with liquid fuels and gaseous fuels . Common examples of solid fuels include wood, charcoal, peat, coal, Hexamine fuel tablets, wood pellets, corn, wheat, rye, and other grains . Solid fuels are extensively used in rocketry as solid propellants . Solid fuels have been used throughout human history to create fire and solid fuel is still in widespread use throughout the world in the present day . </P> <P> Wood fuel can refer to several fuels such as firewood, charcoal, wood chips sheets, pellets, and sawdust . The particular form used depends upon factors such as source, quantity, quality and application . In many areas, wood is the most easily available form of fuel, requiring no tools in the case of picking up dead wood, or few tools . Today, burning of wood is the largest use of energy derived from a solid fuel biomass . Wood fuel can be used for cooking and heating, and occasionally for fueling steam engines and steam turbines that generate electricity . Wood may be used indoors in a furnace, stove, or fireplace, or outdoors in a furnace, campfire, or bonfire . As with any fire, burning wood fuel creates numerous by - products, some of which may be useful (heat and steam), and others that are undesirable, irritating or dangerous . There is debate as to whether burning wood can be considered carbon neutral, as technically the wood cannot release more carbon than was sequestered during its growth, although this does not take account of other impacts such as deforestation and rotting has on the carbon footprint . When harvested in a sustainable fashion wood is usually considered to be a renewable solid fuel . </P> <P> Although wood is a form of biomass, the term usually refers to other natural plant material that can be burnt for fuel . Common biomass fuels include waste wheat, straw, nut shells and other fibrous material . </P>

What is a solid fossil fuel that is often used to generate electricity