Solidfuel

Solid fuel refers to a fuel that is solid at room temperature and releases energy by combustion. It encompasses natural materials such as wood, peat, and charcoal, as well as processed products such as coal, coke, briquettes, and wood pellets. It also includes fuels produced from waste, such as refuse-derived fuels, used for heating, cooking, and various industrial applications. Solid fuels are used in a range of equipment from domestic stoves to furnaces and power plants.

Energy content varies by material. Coal typically provides about 24–33 MJ per kilogram on a dry basis, wood around 15–18 MJ/kg, charcoal about 29–33 MJ/kg, and wood pellets around 16–19 MJ/kg. Moisture, ash content, and particle size influence burn rate and efficiency. Combustion of solid fuels produces heat as well as emissions such as carbon dioxide, water vapor, sulfur compounds, particulates, and nitrogen oxides, with emissions increasing if combustion is incomplete or equipment is inefficient.

Advantages include relatively high energy density, straightforward storage, and wide availability. Drawbacks include air pollution, ash waste, moisture sensitivity, and the need for adequate ventilation and proper handling. Some solid fuels, notably coal and coke, play central roles in certain industrial processes such as metallurgical operations, while solid biofuels are used for heating and power in renewable-energy contexts when produced and sourced sustainably.

History and use: solid fuels have supported human energy needs for millennia, from traditional cooking and heating to industrialization. Storage, safety, and environmental considerations continue to influence their selection and regulation.