The use of oxygenates, i.e. fuel additives containing oxygen have always been of interest. Compounds such as the ethers, and alcohols, particularly ethanol and methanol, fall within this classification.
Their use ability as readily combustible materials has always suggested use as a combustion aid. More recently legislation in the United States has meant that a minimum of 2.0% alcohol should be present in fuel to aid cold starts as a means of reducing carbon dioxide and hydrocarbon emissions during the period when the engine temperature is too low for efficient combustion.
With the realisation that the fossil fuel supply is limited, interest in alcohols as alternative fuels or as fuel extenders has reawakened. One common problem has been that mixtures of hydrocarbons and alcohol, although miscible, at ambient temperatures and at in wide range of proportions, suffer from sensitivity to water contamination. The water causes a separation into ethanol and hydrocarbon phases, which Is undesirable for engines designed to operate at one setting. Consequently to take into account of this condition, a homogenous fuel is important.
Most work with alcohol and diesel mixtures has employed additives to stabilize the ethanol/diesel fuel. A high content of oxygenates (~20%) has been achieved, though no distinction was made between the additive and alcohol content In the fuel. Some of the problems of using alcohol as diesel extender have examined in this report.