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
Ethanol fuel by country oil and to reduce the amount of greenhouse gases produced. The plan also calls for an increase in ethanol producing crops and tax breaks for flex-fuel vehicles and other alternative fuel vehicles. The introduction of the blend of 7% ethanol was postponed in September 2008 until the beginning of 2009. This delay was due to a request by the national association of fuel retailers to have more time available to adapt their fueling infrastructure. Additional delays caused another postponement, as fueling stations were not ready yet for handling ethanol fuel, and now implementation is expected for November 2009. Despite the