Advantages of Ethanol
Advantages of Ethanol
As a renewable fuel, ethanol produces less fossil CO2 than conventional fuels.
Particulate emissions are lower with ethanol than with conventional fuels.
butadiene and benzene levels decrease as the ethanol concentration increases.
Ethanol contains less sulfur than conventional fuels.
Disadvantages of Ethanol
The chemical emulsifiers and ignition improvers used to blend ethanol may contain harmful chemicals. There are higher emissions of formaldehyde and acetaldehyde from ethanol vehicles than from diesel vehicles. There may be an odour problem.
Hydrated Ethanol
Ethanol (C2H5OH) is an alcohol, an oxygenated organic carbon compound. It is the intoxicating
component of alcoholic beverages, and is also used as a solvent (methylated spirits).
By contrast, diesel is a mixture of a range of hydrocarbon compounds, none of which contains oxygen. In blended fuels, the addition to diesel of the oxygen contained in the alcohol changes a number of important fuel characteristics. These include changes in combustion properties, energy content and vaporisation potential.
Ethanol will easily blend with gasoline but not with diesel. Alcohols can be used in diesel engines by either modifying the fuel or by extensive engine adaptations.
Hydrated ethanol can be produced from wheat, sugar cane, molasses and wood and from non- renewable resources. Hydrated ethanol production is a one-stage refining process, unlike the two-stage anhydrous ethanol. However, the upstream emissions for ethanol production will be different for every process.
Ethanol can be manufactured from:
-biomass via the fermentation of sugar derived from grain starches or sugar crops;
-biomass via the utilisation of the non-sugar lignocellulosic fractions of crops;
-petroleum and natural gas via an ethylene (C2H4) intermediate step (reduction or steam cracking of ethane [C2H6] or propane [C3H8] fractions).
Diesel fuel has very low vapour pressure, but the addition of alcohol to diesel (for example diesohol) creates a fuel with a vapour pressure similar to that of ethanol. While modern gasoline vehicles have some evaporative emission control measures, diesel vehicles do not. Evaporative emissions may be a significant problem from unmodified vehicles using ethanol based fuels, but this needs to be tested. To contain evaporative emissions from vehicles using alcohol fuel, measures may need to be implemented to control fuel vapour pressure.
Ethanol is not persistent in the environment. Virtually any environment supporting bacterial
populations is believed to be capable of biodegrading ethanol. Atmospheric degradation is also
expected to be rapid. Provided that the source of ethanol is not fossil fuels then it satisfies ESD
principles.
Ethanol from sugar or wheat is liable to be a niche fuel and thus there are no sustainability issues associated with it. Large-scale usage of ethanol will require ligno-cellulosic production to be economical.
Advantages of Ethanol