The process of biodiesel production involves two phases. The first phase is the extraction of crude oil from seeds and the second is the transesterification of the crude oil into biodiesel. The biodiesel extraction process involves the use of machines to extract the oil from the seed. This produces crude jatropha oil, and hull and press cake as by-products. Laboratory results show that around 2.9 kg of seeds can produce 1 liter of crude oil. On the other hand, the transesterification of crude oil is a process that uses chemicals like methanol and catalysts such as caustic soda18. This produces jatropha methyl ester (JME) as its main product and glycerin as its by-product. Ten liters of crude jatropha oil produces 8.5 liters of JME. The results of laboratory tests show that JME passes the American standard (ASTM D6751) and European standard (EN 14214) for biodiesel. Moreover, analysis of crude jatropha oil shows that it is comparable to bunker fuel.
The use of small scale mechanical press for the extraction of oil from jatropha seeds, combined with the microemulsification of jatropha oil to produce fuel for compression ignition engines, appears to be a viable option for wide application in many parts of most developing countries, including the Philippines. In the countryside where land is available and labor is plentiful and relatively cheap, jatropha curcas may be grown and the seeds manually harvested. Small scale jatropha oil extraction facilities may be installed together with a microemulsification plant. The extraction process using a small mechanical press followed by filtration is shown schematically in Figure 3.1. The fruits are sun-dried, manually dehulled, and the seed further dried under the sun. The sundried seeds are then sent to a mechanical press for the extraction of oil. The press cake is removed from the bottom of the equipment and may be used as fuel for cooking and other purposes. The crude jatropha oil is sent to a plate-andframe filter press to remove residual solids. The filtered jatropha oil is ready and suitable as feedstock in a small-scale microemulsification plant. The MHF that is produced can be used to run farm tractors, trucks, cars and jeepneys, and to operate compression ignition engines to supply electricity to the community or run irrigation pumps.
Sun-dried jatropha seeds are fed into the mechanical extraction equipment (green-colored equipment shown on the right side of the top picture and also in the bottom picture). Crude jathropha oil is sent to a plate-and-frame filter press to remove residual solids (not shown in the top picture but shown behind the mechanical press in the bottom picture) and the filtered jatropha oil is stored in a stainless steel cylindrical storage tank (shown to the left of the jatropha press in the top picture). The filtered jatropha oil is then sent to the MHF machine (shown as the silver-colored equipment in the middle of the photo and also in the middle photo) for processing. A proprietary additive is added and the solution recirculated for two hours through the machine. The final product is filtered through a 5 micron filter (shown as a small cylindrical tube located below the MHF machine, top and middle photo).