1.1.1 Ethanol

Bioethanol is a clean-burning (emits less CO2 and other green house gasses due to availability of free O2), non-petroleum liquid fuel that is considered to be a safe sup­plement to gasoline for transportation. The production and combustion of ethanol do not contribute to the total amount of carbon dioxide in the atmosphere [3, 21]. Ethanol can be mixed with gasoline in 10% (E10), 20% (E20), and 22% (E22) blends without engine modifications, but higher-level blends (such as 85% or 95%) require some engine modification. As a fuel additive, ethanol provides oxygen to the fuel, thus improving fuel combustion and reducing tailpipe emissions of carbon dioxide and unburned hydrocarbons.