A study of energy harvesting from piezoelectrics using impact forces

Piezoelectric elements can be used to harvest electrical energy when impact forces are applied to their surfaces. Often, however, only the peak voltages, or peak power output is used as a measure of device performance, and the total energy harvested during an impact force is overlooked. For energy harvesting applications, such as small-scale piezoelectric batteries, the total energy generated over an impact cycle should be considered. In this paper the total energy efficiency of several commercially available piezoelectric materials are evaluated using impact testing. The results revealed that different materials have significantly different energy efficiencies due to factors such as material type and device construction. Further, it was found that peak power output is not always the most appropriate measure of device performance for energy conversion applications.