Initial evaluation of fatty acid methyl esters (biodiesel) from pili pulp (Canarium ovatum) and sigarilyas seed (Psophocarpus tetragonolobus) as diesel engine fuel

In recent years, biodiesel has earned worldwide reputation as a promising alternative engine fuel. However, the cost of vegetable oils, which escalates its price to three to four, or even five times the price of petroleum-based diesel, remains the main hurdle for its commercial success. Yet, other issues arise from raw materials or feedstock\u27s available to date. In the Philippines for instance, coconut oil and jatropha curcas (tubatuba) pose concerns of supply and toxicity, respectively. Thus, the development of this renewable fuel as a legitimate engine fuel warrants the search for more viable feedstocks. In this study, fatty acid methyl esters (biodiesel) derived from oils of pili pulp (Canarium ovatum) and sigarilyas seed (Psophocarpus tetragonolobus) were investigated as diesel engine fuel. Physical and chemical properties such as kinematic viscosity, density, cloud point, total glycerol, free glycerol, acid value, sulfur, sulfated ash and iodine value were determined. These properties were then compared against set limits in existing biodiesel standards and with properties of coco-methyl esters or CME. Biodiesel from pili demonstrates acceptable fuel properties and appears suitable as diesel engine fuel. All properties determined are within specifications in the Philippine, American and European standards. This suggests that this fuel should be: (1) less susceptible to engine problems such as fuel injection system leakages and poor atomization based on its kinematic viscosity (4.44 mm2/s), (2) safe to store and transport because of its high flash point (155 ºC) and (3) due to its low iodine value (69), can be exempt to engine problems resulting from auto-oxidation of unsaturated components and may possibly, have good oxidative stability properties. Its cold flow performance however needs further investigation since no specification exists for cloud point. Similar to biodiesel from pili, biodiesel from sigarilyas has acceptable fuel properties and should have the same engine performance, storage and handling advantages. Its kinematic viscosity, which was measured to be 4.93 mm2/s, exceeds the maximum limit of 4.5 mm2/s in the Philippine standard but still conforms to specifications in the American and European standards. Its other key properties are \u3e160 ºC for flash point and 82 for iodine value. However, its cold flow performance is a major concern since its cloud point (29 ºC) exceeds even the mean ambient temperature in lowland areas in the country (26.6 ºC). Overall, biodiesel from sigarilyas appears more suitable as a diesel blend because of its expected poor cold flow performance