Essay Assess The Potential Of Ethanol As An Alternative Fuel

Assess the potential of ethanol as an alternative fuel and discuss advantages and disadvantages of its use. (8 marks)
The use of ethanol has great potential because it is a renewable resource that can be produced by the fermentation of glucose in plant material, particularly sugar cane. This makes it more desirable because unlike fossil fuels, the most common fuel source, the supply of ethanol will never exhaust. The presence of oxygen in the ethanol molecule (C2H5OH) means that combustion is almost always complete, which is more environmentally sustainable as the carbon (soot) and toxic carbon monoxide are not produced. As the products of complete combustion, water and dioxide, are also the reactants in the photosynthesis of plants, the cycle

The typical engines of today can only safely use E10 and so must be modified before using high concentrations of, or pure, ethanol. However, the presence of ethanol lowers the fuel economy. This is because ethanol has a lower heat of combustion, so more ethanol would be required to travel the same distance as when using petrol. Ethanol is also corrosive to fuel lines and engines because it is a solvent and thus absorbs water and dirt very easily. Economically, ethanol is far more expensive to produce than the hydrocarbons used for fuel such as octane. Large areas of land would be needed to grow the biomass needed to produce ethanol. This can cause environmental problems such as soil erosion, deforestation, fertiliser run-off and salinity, as well as impacting food prices due to the loss of arable land. Considerable amounts of energy are also required in the industrial production of ethanol, including the production of crops to extract glucose and the distillation of pure ethanol. Ethanol also has a higher flash point than petrol, so more energy is required to reach the temperature necessary for combustion to occur. Moreover, the environmental benefit of using ethanol as a fuel is made redundant by the excess of carbon dioxide produced by the fermentation of sugars from