Fossil fuel embedded energy is still photosynthetic in origin. Terrestrial plants, on the other hand, tended to form coal and methane. Many of the coal fields date to the Carboniferous period of Earth's history. Terrestrial plants also form type III kerogen, a source of natural gas. There is a wide range of organic, or hydrocarbon, compounds in any given fuel mixture. The specific mixture of hydrocarbons gives a fuel its characteristic properties, such as boiling point, melting point, density, viscosity, etc. Some fuels like natural gas, for instance, contain only very low boiling, gaseous components. Others such as gasoline or diesel contain
Nuclear Fuel Services Nuclear Fuel Services Nuclear Fuel Services Inc. (NFS) is an American company that has been a major supplier of fuel for the United States Navy's fleet of nuclear-powered vessels since the 1960s. In recent years it has also reprocessed weapons-grade uranium into nuclear reactor fuel. It operates a gated complex in Erwin, Tennessee. NFS is a subsidiary of BWX Technologies, Inc. The company has emerged as America's leader in converting surplus weapons-grade uranium from U.S. Cold War stockpiles into valuable low-enriched uranium fuel material to power commercial nuclear power plants. Known as downblending, the proprietary NFS process is currently being