Ethanol as a fuel and a renewable resource

Ethanol is a liquid which readily burns:

C2H5OH(l) + O2(g) => CO2(g) + H2O(l)

It is easily transported, and has been suggested as a possible alternative liquid fuel for automobiles. It can be mixed with petrol to give gasohol, such that ordinary petrol engines do not need to be modified, and ethanol and gasohol both release less air pollution than petrol. Ethanol can be produced by fermentation of starches and sugars from plant material. Essentially ethanol is made of CO2, water and sunlight (via glucose) and when it is burnt it returns to CO2 and water which can be re-converted to ethanol, hence a renewable resource.