In the ultrasonic reactor method, the ultrasonic waves cause the reaction mixture to produce and collapse bubbles constantly; this cavitation simultaneously provides the mixing and heating required to carry out the transesterification process. Use of an ultrasonic reactor for biodiesel production can drastically reduce reaction time and temperatures, and energy input. Using such reactors, the process of transesterification can run inline rather than using the time-consuming batch processing. Industrial scale ultrasonic devices allow for processing of several thousand barrels per day.