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 the largest and most successful bio-fuel programs in the world, involving production of ethanol fuel from sugarcane, and it is considered to have the world's first sustainable biofuels economy. In 2006 Brazilian ethanol provided 18% of the country's road transport sector fuel consumption needs, and by April 2008, more than 50% of fuel consumption for the gasoline market. As a result of the increasing use of ethanol, together with the exploitation of domestic deep water oil sources, Brazil reached in 2006 a volumetric self-sufficiency in oil supply, but is not effectively self-sufficient, since most of its locally extracted oil is