Abstract: The instant invention describes a method and system for producing biodiesel which increases energy efficiency by reducing the overall amount of energy associated with producing the biodiesel. Unlike most systems which use a batch procedure, the instant method and system utilize a continuous flow sonification procedure which provides for reactions to take place in tubes as the biodiesel moves along through the process. The continuous flow sonification procedure is performed in two main stages, utilizing the steps of acid esterification, transesterification, and a waterless washing.