Evaluation of Raffia Palm Weevil Larvae (Rhynchophorus phoenicis) as a Potential Biodiesel Resource

Abstract

Ethical issues arise when arable agricultural land and heavy agronomic inputs are used to cultivate crops for energy production such as biodiesel. Alternative feedstocks for biodiesel production might solve the food energy competition scenario. White raffia larvae (Rhynchophorus phoenicis) appears as a credible option because of its high lipid content, a relatively short life cycle and its abundance in the tropical environment. This study investigated the use of R. phoenicis larvae for biodiesel production. R. phoenicis larvae was grown on raphia stipe for 21 days and used for crude grease extraction. The extracted crude grease was converted into biodiesel by acid-catalyzed esterification and alkaline-catalyzed trans-esterification. The physicochemical properties of crude grease and biodiesel were investigated using the European biodiesel standard (EN14214), and the American Society of Testing materials specifications. The defatted extraction residue was analyzed using the AOAC protocol. Results revealed that the cetane number, heating value, acid value and density of crude grease were found to be higher than those of rapeseed while kinematic viscosity and iodine values were smaller. The conversion yield of free fatty acids of crude grease into biodiesel reached 85%. The fuel properties of biodiesel obtained are quite comparable with those of EN 14214 and ASTM standard. The defatted extraction residue exhibited high protein content (66,76%) and mineral which make it suitable for animal and human feed supplement. Therefore, it was concluded that, the R. phoenicis larvae can be used as valuable feedstock for biodiesel production and animal feed resources.