American Journal of Energy Engineering 2014; 2(1): 1-15 Published online February 20, 2014 (http://www.sciencepublishinggroup.com/j/ajee) doi: 10.11648/j.ajee.20140201.11 Synthesis and characterization of biodiesel from castor bean as alternative fuel for diesel engine Molla Asmare * , Nigus Gabbiye Centre of Competence for Sustainable Energy Engineering, Institute of Technology, Bahir Dar University, Bahir Dar, Ethiopia Email address: mollaasmare98@gmail.com (M. Asmare) To cite this article: Molla Asmare, Nigus Gabbiye. Synthesis and Characterization of Biodiesel from Castor Bean as Alternative Fuel for Diesel Engine. American Journal of Energy Engineering. Vol. 2, No. 1, 2014, pp. 1-15. doi: 10.11648/j.ajee.20140201.11 Abstract: This paper deals with the transesterification of Ricinus Communis (RC) oil with methanol to produce biodiesel in the presence of KOH as a catalyst. Moreover, this study analysis the fuel properties of RC biodiesel and diesel fuel blend to use castor oil methyl ester as a possible alternative fuel for diesel engines. Various properties of the RC biodiesel and their blends such as density, kinematic viscosity, iodine value, saponification number, Cetane number, heating value, flash point and acid value were determined. The experimental results were compared well with American Society for Testing and Materials (ASTM D6751) and European biodiesel standards (EN 14214). The experimental design as well as statistical analysis were done and analyzed using design expert 8.0.7.1 version soft ware. The predicted optimum conditions for castor oil biodiesel production were a reaction temperature of 59.89 0 c, methanol to oil ratio of 8.10:1 and a catalyst of 1.22 wt% of oil. The methyl ester content under these optimum conditions was 94.5% w/w of oil, and all of the measured properties of the biodiesel met the international standards of EN14214 and ASTM D 6751 with the exception of density and viscosity. Therefore, the viscosity and density of the ester was high and further reduced by blending with diesel fuel up to B45 to satisfy within the ASTM D6751 and EN 14214 limits for biodiesel. Keywords: Castor Seed, Castor Oil, Biodiesel, Transesterification, Blend, Response Surface Methodology 1. Introduction The developments of societies have accompanied by an increase in growing energy needs. Their energy requirements have achieved through the combustion of various materials (oil, coal and natural gas) which considered as fossil fuels and therefore non-renewable, which creates environmental problems. These facts have converged in the search for renewable energy sources such as Biofuels: a non-toxic, biodegradable, agricultural source, with a high heating value and oxygen content [1]. Global warming is one of the greatest environmental threats facing our planet caused by increasing in atmospheric Green House Gases (GHG) due to human activities since the start of the industrial era [2]. When fuels were burnt, there are just a few basic types of primary exhaust emissions (oxides of nitrogen (NO X ), Carbon monoxide (CO), hydrocarbons (HC), Carbon dioxide (CO 2 ) and particulate matter (PM)). In addition to these, primary pollutants reactions in the atmosphere generate secondary pollutants that cause acid rain, photochemical smog and tropospheric ozone depletion. Many of these pollutants have serious implications on human health and the environment. Consequently, many countries have established strict environmental policies and regulations that must meet by all automobile manufacturers. The search for alternative fuels started when the pollution created by the burning of fossil fuels shows severe environmental problems because biofuels have a significant role in overall reduction of CO 2 emissions [3]. Bioethanol is the most well known biofuels used in gasoline engines. Similarly, manufacturers have worked with biodiesel, as it is the most common alternative fuel for traditional diesel engines. Among the most promising sources, vegetable oils and animal fats have attracted much attention as a potential resource for the production of biodiesel, which is quite similar to conventional diesel in its main characteristics and can be easily blended with diesel fuel in any proportion with minor or no modifications to the engine as well as fuel system [4]. The production and use of biodiesel have increased significantly in many countries around the world