ABSTRACT
204Biodiesel is one of the very important renewable energy sources targeted to meet the ever-growing demands of energy worldwide, though currently the higher costs of production has hampered the potential use at commercial scale. Use of sustainable feedstocks and the process intensification approaches can help in obtaining significant reduction in the costs of production. As the chemical routes for synthesis of biodiesel viz. esterification and transesterification are limited by the severe mass transfer effects, application of hydrodynamic cavitation reactors as process intensification approach holds significant promise. The book chapter covers different aspects including the basic mechanism of expected intensification, fundamentals of hydrodynamic cavitation, different reactor configurations, overview of different applications and important design and operational guidelines for the maximizing the extent of intensification. The focus of the analysis of different studies was on the use of sustainable feedstocks including the nonedible oil and waste cooking oil. Possible combinations of hydrodynamic cavitation reactors with other techniques of intensification have also been discussed. The potential for scale up of hydrodynamic cavitation reactors for biodiesel synthesis has also been analyzed and also the comparison with more conventionally used form of cavitational reactors i.e. ultrasound based reactors has been presented. Overall it appears that hydrodynamic cavitation reactors can give significant process intensification benefits mainly attributed to the intense physical effects of cavitation phenomena and can lead to lower reaction times, requirement of lower excess of reactants as well as reduction in the operating temperature, all pointing towards significant savings in the cost of production.
