Carbon the very large masses of carbonate rock (limestone, dolomite, marble and so on). Coal is very rich in carbon (anthracite contains 92–98%) and is the largest commercial source of mineral carbon, accounting for 4,000 gigatonnes or 80% of fossil fuel. As for individual carbon allotropes, graphite is found in large quantities in the United States (mostly in New York and Texas), Russia, Mexico, Greenland, and India. Natural diamonds occur in the rock kimberlite, found in ancient volcanic "necks", or "pipes". Most diamond deposits are in Africa, notably in South Africa, Namibia, Botswana, the Republic of the Congo, and Sierra Leone.
Direct carbon fuel cell reaction path> C + CO → 2CO Cathode reaction O + 4e → 2O Direct carbon fuel cell A Direct Carbon Fuel Cell (DCFC) is a fuel cell that uses a carbon rich material as a fuel such as bio-mass or coal. The cell produces energy by combining carbon and oxygen, which releases carbon dioxide as a by-product. It also called coal fuel cells (CFCs), carbon-air fuel cells (CAFCs), direct carbon/coal fuel cells (DCFCs), and DC-SOFC. The total reaction of the cell is C + O → CO. The process in half cell notation: Despite this release of carbon dioxide,