Anthracite latter in two or three sizes, all three being above in (38 mm) size on round-hole screens. High grade (HG) and ultra high grade (UHG) anthracite are the highest grades of anthracite coal. They are the purest forms of coal, having the highest degree of coalification, the highest carbon count and energy content and the fewest impurities (moisture, ash and volatiles). High grade and ultra high grade anthracite are harder than standard grade anthracite, and have a higher relative density. An example of a chemical formula for high-grade anthracite would be CHONS, representing 94% carbon. UHG anthracite typically has a
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,