News and Resources : Green Alternatives - Hydrated and Anhydrous Ethanol
The development and use of alcohol fuels has been driven by the desire to find renewable substitutes for imported petroleum based fuels. Ethanol is made from sugar beet, sugar cane, wheat, molasses and wood and can be produced in two forms; hydrated and anhydrous.
Hydrated ethanol has a purity of 95% making it suitable for blending with an ignition improver, or as a 15% emulsion in diesel. A second stage refining process is needed to produce anhydrous ethanol (100% purity) for use in ethanol blends in petrol. The addition of an unpleasant or a poisonous substance to prevent oral consumption denatures most industrial ethanol.
Ethanol is an alcohol, an oxygenated organic carbon compound. It is the intoxicating component of alcoholic beverages, is used as a solvent (methylated spirit), and is widely used in the chemical and pharmaceutical industry. In contrast, diesel is a mixture of a range of hydrocarbon compounds, none of which contain oxygen. In blended fuels the addition to diesel changes the combustion properties, energy content and vaporisation potential. The energy content of ethanol is between 21 to23MJ/l. This compares with 38.6MJ/l for diesel.
The ability of ethanol to contribute to a reduction of greenhouse gas emissions on a full fuel-cycle basis is dependent upon the nature of the feedstock and the source of power used for the production process. Tests to measure particulate matter ranged from 2mg/km up to 431 mg/km dependent on the feedstock; these compare with 43mg/km emission for low sulphur diesel. On non-methanic hydrocarbon, emissions varied between 0.026g/km and 8.66 g/km compared with 0.292g/km for low sulphur diesel.
Alcohol does not contain sulphur atoms and therefore an increase in alcohol content will reduce the emissions of sulphur dioxide. Oxides of nitrogen emissions from ethanol are lower than from diesel, even without a catalytic converter. As a renewable fuel it produces less fossil CO2 than conventional fuels.
