Theoretical and Experimental Evaluation of Two Roadway Piezoelectric-Based Energy Harvesting Prototypes

This paper presents the results of a theoretical and experimental study aiming to develop a stress-based roadway energy harvesting system. It describes two prototypes using piezoelectric elements. Prototype I consisted of 4, 8, and 16 8-mm-diameter cylindrical piezoelectric elements sandwiched between two copper plates. Prototype II consisted of a stack of 11 50-mm-diameter piezoelectric elements connected in parallel by alternating their polarities. Basic piezoelectric theory suggests that the relationship between power output and stress is nonlinear. Finite-element (FE) analysis shows a dependency of the power output of a cylindrical piezoelectric unit on loading frequency. The experimental evaluation included testing the prototypes in a universal testing machine under controlled temperature conditions. In addition, Prototype II was subjected to repetitive loads using an asphalt pavement analyzer without observing any loss in power output. Three-dimensional dynamic FE simulations were performed to determine the optimum installation depth of an energy harvesting module in an asphalt concrete pavement structure. Assuming moderate traffic levels and installation in the right-wheel path only, the energy output estimated per Prototypes I and II was 360 and 171 W-h annually. This technology shows promise in powering self-standing data acquisition systems or light-emitting diode (LED) lights in rural areas where there are no electrical power lines roadside.