Production, evaluation and testing of biodiesel : case studies of Moringa oleifera and selected tropical seed oils.

Abstract

Production, evaluation and comparative testing of biodiesel from Moringa oleifera seed oil and selected tropical feedstock oils were undertaken in this study. From studies, Moringa oil has higher oil yields and excellent fuel properties and as a result is a good choice as feedstock to produce biodiesel as well as being an optimizer through the process of hybridisation with other feedstocks, to produce hybrid biodiesel fuels. Production processes were therefore designed to extract oils from the seeds of Moringa, Jatropha, Sandbox tree and Yellow oleander. Transesterification, a biodiesel production process, was deployed using methanol in the presence of NaOH, KOH as catalysts. The use of residual ash from plantain peels as a local catalyst was evaluated as an established production variable. The study also determined production model protocols for transesterification and optimization of production variables (alcohol/oil ratios, reaction temperatures, reaction time and agitation). The hybridization process was developed to improve the quality of biodiesel produced from other feedstocks. Hybridization is the co-mingling of oils of different feedstocks before and after transesterification. This became a major contribution of the study. Hybridisation was carried out using two process pathways termed in situ and ex situ hybridization. Fuel properties of oil feedstocks vary depending on sources and chemo-physical composition and with hybridization, the output is improved and standardized. Oils and biodiesel from the feedstocks were analyzed and their properties determined; namely, chemo-physical, rheological, thermal and gaseous emission properties. The methodologies used and results obtained were evaluated in accordance with ASTM, AOAC, IP and SANS standards. The produced biodiesel and hybrids were further subjected to engine performance tests and analysis using a four strokes diesel engine (TD 302). The observations were simulated and computed, evaluated and analyzed. As new players in the alternative fuel market, the biodiesel potential of these feedstocks is huge as a source of fuel for automobiles and other energy needs. Improved specific fuel properties are: viscosity, specific gravity, refractive index, cetane index, fatty acid composition, free and total glycerides, acid value, peroxide value, oxidative stability, density, flash points, pour points and calorific values.