Formation Process of Toxic Substances from Biomass Fuel

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Biomass fuel is a good substitute fuel for petroleum because it is reproducible and because there is very little emission of CO_2 throughout the ecosystem cycle. Methyl-esterificated fuel produced from vegetable oil is particularly beneficial for diesel engines because almost the same engine performance as that achieved by the use of gas oil is possible but there is much less exhaust smoke. However, since oxygen molecules in esterified fuel contain oxygen, there is a risk that more toxic substance containing oxygen will be emitted from a diesel engine in which esterified fuel is used than from an engine in which gas oil is used as fuel.As the experiment result, it is safe to say that a diesel fuel for the automobile van be made from esterified fuel. The differences in the constituent component and esterification ratio of the vegetable oil will be reflected in the methyl eater fuel as the difference in its component. However, this will not make an impact upon engine performance and emission characteristics in any great way. As for the emission of such specified harmful substances as methanol, formaldehyde, acetaldehyde and acrolein etc, the number of dublebonds in the fatty acid that constitute methyl eater was found to be responsible.In comparison with gas oil, regardless of the combustion chamber types, the methyl ester fuel had 1,2 to 3times more of specified harmful substance such as methanol, formaldehyde, acrolein and benzene in the exhaust gas. The DI engine was found to emit a large quantity of particulates in the low to middle load range. A large portion of the particulates in question consist of SOF components. However, with the IDI engine, there was no significant difference in the emission of particulates between methyl ester fuel and light oil. We need to take countermeasures against the tempura small which is caused by propionaldehyde.