Lignite often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low heat content. When removed from the ground, it contains a very high amount of moisture which partially explains its low carbon content. Lignite is mined all around the world and is used almost exclusively as a fuel for steam-electric power generation.
Coke is a grey, hard, and porous coal-based fuel with a high carbon content and few impurities, made by heating coal or oil in the absence of air—a destructive distillation process. It is an important industrial product, used mainly in iron ore smelting, but also as a fuel in stoves and forges when air pollution is a concern.
Wood gas is a fuel gas that can be used for furnaces, stoves, and vehicles. During the production process, biomass or related carbon-containing materials are gasified within the oxygen-limited environment of a wood gas generator to produce a combustible mixture. In some gasifiers this process is preceded by pyrolysis, where the biomass or coal is first converted to char, releasing methane and tar rich in polycyclic aromatic hydrocarbons.
Producer gas is fuel gas that is manufactured by blowing through a coke or coal fire with air and steam simultaneously. It mainly consists of carbon monoxide (CO), hydrogen (H2), as well as substantial amounts of nitrogen (N2). The caloric value of the producer gas is low (mainly because of its high nitrogen content), and the technology is obsolete. Improvements over producer gas, also obsolete, include water gas where the solid fuel is treated intermittently with air and steam and, far more efficiently synthesis gas where the solid fuel is replaced with methane.
Anthracite, also known as hard coal and black coal, is a hard, compact variety of coal that has a submetallic lustre. It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the highest ranking of coals.
A maceral is a component, organic in origin, of coal or oil shale. The term 'maceral' in reference to coal is analogous to the use of the term 'mineral' in reference to igneous or metamorphic rocks. Examples of macerals are inertinite, vitrinite, and liptinite.
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, dry dung, 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.
White coal is a form of fuel produced by drying chopped wood over a fire. It differs from charcoal which is carbonised wood. White coal was used in England to melt lead ore from the mid-sixteenth to the late seventeenth centuries. It produces more heat than green wood but less than charcoal and thus prevents the lead evaporating. White coal could be used mixed with charcoal for other industrial uses than lead smelting. White coal was produced in distinctive circular pits with a channel, known as Q-pits. They are frequently found in the woods of South Yorkshire.
A briquette is a compressed block of coal dust or other combustible biomass material used for fuel and kindling to start a fire. The term derives from the French word brique, meaning brick.
The Clean Air Act 1956 was an Act of the Parliament of the United Kingdom enacted principally in response to London's Great Smog of 1952. It was sponsored by the Ministry of Housing and Local Government in England and the Department of Health for Scotland, and was in effect until 1993.
Sub-bituminous coal is a lower grade of coal that contains 35–45% carbon. The properties of this type are between those of lignite, the lowest grade of coal, and those of bituminous coal, the second-highest grade of coal. Sub-bituminous coal is primarily used as a fuel for steam-electric power generation.
A cyclone furnace is a type of coal combustor commonly used in large industrial boilers.
Carbochemistry is the branch of chemistry that studies the transformation of coal into useful products and raw materials. The processes that are used in carbochemistry include degasification processes such as carbonization and coking, gasification processes, and liquefaction processes.
A wood-burning stove is a heating or cooking appliance capable of burning wood fuel, often called solid fuel, and wood-derived biomass fuel, such as sawdust bricks. Generally the appliance consists of a solid metal closed firebox, often lined by fire brick, and one or more air controls. The first wood-burning stove was patented in Strasbourg in 1557. This was two centuries before the Industrial Revolution, so iron was still prohibitively expensive. The first wood-burning stoves were high-end consumer items and only gradually became used widely.
Biomass briquettes are a biofuel substitute made of biodegradable green waste with lower emissions of greenhouses gases and carbon dioxide then traditional fuel sources. This fuel source is used as an alternative for harmful biofuels. Briquettes are used for heating, cooking fuel, and electricity generation usually in developing countries that do not have access to more traditional fuel sources. Biomass briquettes have become popular in developed countries due to the accessibility, and eco-friendly impact. The briquettes can be used in the developed countries for producing electricity from steam power by heating water in boilers.
Refined coal is the product of the coal-upgrading technology that removes moisture and certain pollutants from lower-rank coals such as sub-bituminous and lignite (brown) coals, raising their calorific values. Coal refining or upgrading technologies are typically pre-combustion treatments and processes that alter the characteristics of coal before it is burned. Pre-combustion coal-upgrading technologies aim to increase efficiency and reduce emissions when coal is burned. Depending on the situation, pre-combustion technology can be used in place of or as a supplement to post-combustion technologies to control emissions from coal-fueled boilers. A primary benefit of refined coal is the capacity to reduce the net volume of carbon emissions that is currently emitted from power generators and would reduce the number of emissions that is proposed to be managed via emerging carbon sequestration methodologies. Refined coal technologies have primarily been developed in the United States. Several similar technologies have been researched, developed, and tested in Victoria, Australia, including the Densified coal technology developed to alter the chemical bonds of brown coal to create a product that is cleaner, stable, exportable and of sufficiently high calorific value to be a black coal equivalent.
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but has since also been applied to other sources of heat energy, such as nuclear energy.
Charcoal is a lightweight black carbon residue produced by strongly heating wood in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, called charcoal burning, often by forming a charcoal kiln, the heat is supplied by burning part of the starting material itself, with a limited supply of oxygen. The material can also be heated in a closed retort. Modern "charcoal" briquettes used for outdoor cooking may contain many other additives, e.g. coal.
The 1962 London smog was a severe smog episode that affected London, England, in December 1962. It occurred ten years after the Great Smog of London, in which serious air pollution had killed as many as 12,000 people. While the 1952 smog had led to the passing of the 1956 Clean Air Act, which restricted the burning of domestic fuels in urban areas with the introduction of smokeless zones, fogs continued to be smoky in London for some years after the act as residents and operators were given time to convert from domestic fuels. The December 1962 smog is thought to have led to the deaths of up to 700 people.
Patent fuel was a 19th-century artificial fuel made in Cardiff in Wales by mixing in a hydraulic press coal and binding substances, like pitch. There were many factories producing this product with the same recipe, thus the only way of identifying them is their shape and imprinted logos. The most well-known patent fuel factories were the Star Patent fuel Co., the Crown Patent fuel, the Cardiff Patent fuel etc. In the late nineteenth century and early twentieth century, south Wales was the main exporter of patent fuel in the world, with around three million tons a year being exported each year in the first decade of the twentieth century. Patent Fuel cubes are exhibited at the National Museum of Wales in UK.
