Fuel were present at the sites. As a fuel, wood has remained in use up until the present day, although it has been superseded for many purposes by other sources. Wood has an energy density of 10–20 MJ/kg. Recently biofuels have been developed for use in automotive transport (for example Bioethanol and Biodiesel), but there is widespread public debate about how carbon efficient these fuels are. Fossil fuels are hydrocarbons, primarily coal and petroleum (liquid petroleum or natural gas), formed from the fossilized remains of ancient plants and animals by exposure to high heat and pressure in the absence of oxygen
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