Flexible and elastic mechanisms for extracting power from a moving fluid. Sheet-like material is deformed during fabrication through an applied force so as to create undulations in said material, whose stresses are maintained through restraining components, thereby maintaining the occurrence of said deformations in the material. When placed in moving fluid, the resulting pressure differentials cause the positions of the undulations within the material to travel along said material in the same direction as the moving fluid. Power is extracted in one of two principle ways. The first is via a mechanical coupling of the sheet-like material to a rotating mechanism, which turns an electro-magnetic dynamo or other output device. The second is via the utilization of a flexible material which exhibits an electrical response to mechanical strain, whereby the strains caused by the travel of undulations along the material create an electrical current which is extracted via two or more electrodes.