A novel hydropower harvesting device

Using the kinetic energy of flowing rivers directly will broaden the hydropower resources. Two designs are presented for the generation of electrical energy. Both designs are connected with a von Karman's hydrodynamic instability. The first is a fluttering flag made of a piezoelectric polymer material, which is bending periodically in turbulent flow. Electrodes on the surface collect the generated charges. Secondly, a microstructured piezo-bimorph is presented. It is placed in an instable flow too, hence continuously bends up- and downward. Power ratings of 7.ImuW per element could be achieved resulting in a power density of 70W/m(3) using the common mechanical theory. Very thin films producible using micro technologies only show a completely different mechanical behaviour. The application of these film like elements could increase the power rating dramatically. Many of those generator bimorphs together with a rectifier are built up to modules which are part of an hydropower harvesting device placed into a flowing river.