Experimental investigations of a new concept of wave energy converter hybridizing piezoelectric and dielectric elastomer generators

A novel concept of a surge wave energy converter for nearshore applications is investigated experimentally. The centimetre-sized prototype developed in this work represents a proof of concept of a submerged system, which entails a hybrid transduction solution for the electrical conversion of wave energy, that uses piezoelectric elements (PZEs) and dielectric elastomer generators (DEG). The idea is to exploit the horizontal pressure gradient and horizontal water velocity underneath the waves to compress the PZE and inflate each half wave period a soft variable capacitance, which composes the DEG. The electrical charges created by the PZE are used to polarize the DEG, which is able to multiply the input energy. This hybridization is conceived to allow the system to generate electrical energy from waves without conventional high voltage supplies, thus reducing production costs and allowing standalone clean electrical generation. The article provides the preliminary fluid-mechanical measurements performed in a wave flume with a first version of the prototype and supported by a model comprising the fluid/structure interaction, the materials response, and the electrical operations. An estimation of the output energy of a small-sized prototype in constant charge mode is computed, and perspectives for optimizing the system are presented.