Solid fuel purposes, such as refining metals. Coal is the largest source of energy for the generation of electricity worldwide, as well as one of the largest worldwide anthropogenic sources of carbon dioxide releases. The extraction of coal, its use in energy production and its byproducts are all associated with environmental and health effects including climate change. Variations such as smokeless coal can be formed naturally in the form of anthracite, a metamorphosed type of coal with a very high carbon content that gives off a smokeless flame when set alight. Coke is a fuel with few impurities and a high carbon
Carbon capture and storage and fossil fuel-based hydrogen production plants. Extracting from air is also possible, although the far lower concentration of in air compared to combustion sources presents significant engineering challenges. Organisms that produce ethanol by fermentation generate cool, essentially pure that can be pumped underground. Fermentation produces slightly less than ethanol by weight. Flue gas from the combustion of coal in oxygen has a large concentration of , about 10-15% whereas natural gas power plant flue gas is about 5–10% . Therefore, it is more energy and cost efficient to capture from coal-fired power plants. Impurities in streams, like sulfurs and water,