Ethanol, also called ethyl alcohol, grain alcohol, or drinking alcohol. When Ethanol is used as part of the fuel, by blending with petrol, for a motor vehicle, it is called fuel-ethanol. Using ethanol instead of tetraethyl lead or MTBE which acts as anti-knocking agents prevents dangerous and poisonous emissions containing lead or MTBE from petrol. Many states in the US have been using 10% ethanol blend in gasoline (petrol) for use in their cars. Brazil has been using up to 24 % ethanol in petrol. Engines of cars do not need any change to use petrol with up to 24 % ethanol in it. Thus using Ethanol in Motor Fuels helps to serve the environment without incurring any cost or effort to modify the engines. Ethanol is produced in two ways. One is through the hydration of ethylene, as a Petrochemical and can also be produced biologically, by by fermenting sugars with yeast. The economical cost of both the processes is dependent upon the prevailing prices of petroleum and of grain feed stocks.