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
Economics of nuclear power plants enrichment facilities, spent fuel repositories, and decommissioning sites — nuclear power proves to be one of the costliest sources of energy". In 2014, Brookings Institution published "The Net Benefits of Low and No-Carbon Electricity Technologies" which states, after performing an energy and emissions cost analysis, that "The net benefits of new nuclear, hydro, and natural gas combined cycle plants far outweigh the net benefits of new wind or solar plants", with the most cost effective low carbon power technology being determined to be nuclear power. Moreover, Paul Joskow of MIT has determined that the "Levelized cost of electricity" (LCOE) metric