High Free Fatty Acid Crude Rice Bran Oil - A Renewable Feedstock for Sustainable Energy and Environment

Biodiesel is a renewable fuel mostly derived from vegetable oils, which has gained greater importance as an alternative source to petroleum derivatives due to its vital role in producing a cleaner environment. While most of the biodiesel-based research has focused on edible and non-edible vegetable oils, very little time has been devoted to the investigation of the use of rice bran oil, especially in its crude form with high levels of free fatty acids (FFA). Since crude rice bran oil (CRBO) with high FFA is not used as edible oil, it can be considered as a potential source of non-edible vegetable oil for utilization as a feedstock for biodiesel production. In the present investigation, high FFA CRBO was subjected to esterification and transesterification processes and the crude rice bran oil methyl ester (CRBME) obtained was tested in a compression ignition (0) engine to determine its ability to replace petroleum diesel and lead to a reduction in pollutants. A 4.4 kW, four-stroke, direct-injection, air-cooled, stationary diesel engine was used in this investigation. CRBME has less emission of unburned hydrocarbon (UBHC), nitrogen oxides (NOx) and smoke density with a marginal increase in carbon monoxide (CO) emissions, when compared with diesel. It was also observed that the brake thermal efficiency of the engine was not affected when the engine was fueled with CRBME. From the experimental results, it is concluded that CRBO with high FFA has better emission characteristics than diesel without any associated loss of power. Hence CRBO with high FFA can be effectively used as a biofuel for the generation of a cleaner environment.