Environmental effects
- Air pollution
Ethanol is clean burning fuel source that combust cleanly (leaving no residue) to form carbon dioxide and water. The Clean Air Act requires the addition of oxygenates to reduce emission of carbon monoxide in U.S. Presently, ethanol is replacing MTBE as an additive as MTBE contaminates underground water. If ethanol is to be used entirely in place of gasoline in vehicles, it is estimated that the total carbon dioxide emission will be reduced by l3%.
The problem facing ethanol production is that ethanol plants released volatile organic compounds (VOCs) than had previously been disclosed - this problem can be off set by installing devices known as thermal oxidizers or catalytic oxidizers to burn off the dangerous gas.
- Global warming
All fuel combustion fuels releases carbon dioxide into the atmosphere, and the fuels produced from biomass are no exceptions. However, Carbon dioxide formed during combustion of bio fuels is off set by that absorbed during annual growth of plants used a biomass feedstock. Taking into consideration the amount of fossil fuel used to grow and process the biomass feedstock, the net greenhouse gas emission reduction is still 20% approximately. A reduction in both the amount of gasoline used and fossil electrical production can mean l00% net green house gas emission reduction.
- Vehicle emissions
Petroleum diesel and gasoline consists of hundreds of hydro carbon chains e.g. benzene, toluene and xylenes which are toxic compounds causing health hazards. The emissions of carbon monoxide, nitrogen oxides and sulphur oxides cause concern about air pollution. Using ethanol as additive to gasoline helps to reduce these harmful emissions. In particular, ethanol adds oxygen to the fuel and aids in complete combustion, thus reducing carbon monoxide emission.
Renewable resources
Ethanol is derived from a renewable resource, such as corn or wheat which makes it different from fossil fuel, which can be eventually exhausted. Ethanol plays an important role in converting energy from difficult to consume sources to more convenient ones: for example from natural gas, solar electric, wind power to ethanol.
Energy balance
Before ethanol can be considered a replacement for fossil fuels, energy produced must be greater than energy required to grow the corn and other crops used as fuel. In other words, it must have a favourable energy balance. Ethanol can be more competitive and the yield will be improved by using different feedstock such as straw or wood chips or fast growing switch grass grown on land not suitable for cash crops. Another way to improve yield is to use hybrids (of corn) designed with higher extractable starch level.
Dependency on foreign oil
U.S.A., Europe and India and China are dependent on foreign suppliers for oil - countries that consume much more fossil fuels than they are extracted from their countries. Therefore, it is necessary to develop ethanol to avoid over dependence of foreign supply of oil.
