Dielectric elastomers for hydro power harvesting

Dielectric elastomers can be used as generators, converting mechanical strain energy into electrical energy using the polymer's capacitive behavior. The amount of energy gain depends, in addition to the mechanical setup of the device, mainly on the material parameters and the energy harvesting cycle used. While the usefulness of small-scale prototypes for harvesting the energy of waves has already been demonstrated, using the capability of flow energy in rivers, based on electroactive polymers, is still a significant challenge. After introducing the basic working principle of dielectric elastomer generators, the most unique energy harvesting cycles are described, considering electrical and mechanical losses. To harvest the energy of flowing waters, a novel flow energy converter based on a simple and environmentally sustainable mechanical design has been developed, consisting of an elastomeric tube with a closing mechanism on the outlet. The stationary stretch of such a tube is comparably small, but the resonant operation offers large tube deformations. The basic mechanisms of the flow energy converter are modeled, and confirmed on the basis of a FSI simulation, and a control concept is proposed. The expected mechanical behavior of the tube is demonstrated with a small-scale prototype. It can be concluded that a very efficient, resource-saving, scalable and lightweight energy harvesting system can be realized at comparably low frequencies in the infrasonic range.