Palm oil and derivatives: Fuels or potential fuels?

Abstract

Scientific and technical information including field trials about uses of palm oil as fuel has been available for more than half a century now. Several ways were investigated, from the simple mixture with petroleum Diesel fuel, to more sophisticated solutions. The quality of vegetable oils in natura as fuel is difficult to assess because of interferences between properties of the triacylglycerols - the main components - and those of the many minor components, their content varying significantly from sample to sample. A methodology set up at Cirad allowed to investigate separately natural triacylglycerols alone and the effect of minor components. In addition to these laboratory experiments, engine test at bench and field trials performed in palm oil producing countries, show that this oil is among the best oils as fuel ; palm kernel oil whose chemical and physical properties are very close to those of the best of the series investigated, namely copra oil, should display also very interesting properties as Diesel biofuel. Both oils do require external adaptation of the engine when using an indirect injection type engine but even heavier adaptations for a direct injection model. Thus for use as Diesel fuel palm and palm kernel oils are suitable for captive fleets or for engine gensets, to balance the adaptation cost by a scale-up effect either on the number of identical engines or on the nominal vegetable oil consumption per set. Direct use of palm et palm kernel oils fits very well with technical and economical conditions encountered in remote areas. It is also possible to mix palm oil to Diesel fuel either as simple blend or as micro-emulsion. Out of the direct use, palm oil methyl or ethyl ester, often referred to as biodiesel, displays properties similar to those of petroleum Diesel fuel. This technical solution which is suitable to feed all kinds of standard compression ignited engines requires a chemical plant for carrying out the alcoholysis reaction and processing of the crude glycerin by-product. Economical outputs depend also on market price of this last commodity. The last technique opening a way for using palm oil as fuel involves catalytic cracking, then allowing to feed any kind of engine -either spark or compression ignited- although a few results are available only from laboratory or small pilot scale experiments. If the economic viability would be favored by scale-up effect for large national or international markets assuming palm oil producing cost would become and remain competitive is spite of lack of harvest mechanization, and oils would remain available for large non food markets, as this is presently the case, there is a lack of technical and economical data. This is especially the case regarding the minimum size required for applying these more sophisticated chemical transformations -alcoholysis and cracking- for supplying energy under most critical conditions found in remote areas where millions of people are facing difficult access to both electric power and transportation fuels. Today large scale production and marketing of palm oil methyl or ethyl ester is under development in oil palm cropping countries like Malaysia, Thailand or Brazil. The follow-up depends on many parameters on environment, social and economic sides.