Flexible Materials Generate Electricity From Gently Flowing Water

Pliant Energy Systems LLC (New York, NY) garnered U.S. Patent 7,696,634 for its 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 the material. According to inventor Benjamin Pietro Filardo, when placed in moving fluid, the resulting pressure differentials cause the positions of the undulations within the material to travel along the material in the same direction as the moving fluid, 

Power is harnessed by the mechanisms in two different ways. In the first way, as the forces of the moving water cause the wave undulations to move along the fronds, stresses are created within the sheet-like material or composite sheet-like material that comprise the fronds or tubes. This sheet-like material consists in whole or in part of a material which exhibits an electrical response to strains exerted within the material. As the wave undulations move along the material in the direction of the moving fluid, stresses also move through the material in the direction of the moving fluid, and electrical energy is generated from these stresses in the material.

Existing examples of such materials include electroactive polymers (EAPs), which may exhibit electrostrostrictive, electrostatic, piezoelectric, and/or pyroelectric responses to electrical or mechanical fields, as well as ionic EAPs, shape memory alloys, and nanowires. At least two electrodes are utilized for embodiments extracting power in this first way.

The second way that energy is harnessed by the mechanisms is by coupling the mechanical action of the traveling undulating motions of the material as described above to a shaft or axle. This axel turns an electromagnetic dynamo or other output device, such as for example, a pump.  

Progress in the field of materials science is seeing the emergence of novel materials capable of converting mechanical strain within a material into electrical energy without a rotating mechanism, and therefore, without a turbine and electro-magnetic dynamo. The potential advantages of turbine-free power generation include simplicity of design with fewer or no articulated moving parts and potentially greater efficiency. Pliant Energy Systems device embodies a range of mechanisms that share common principles for the creation of scalable hydro-electric generators, employing these novel materials.

One important application of the device is in the field of so-called "free-flow" or "run-of-the-river" hydroelectric power generation, where the kinetic energy of rivers, streams or tidal currents is harnessed without the need for dams. A dam built in the path of flowing water creates a high energy potential differential above and below the dam, allowing water to pass through turbines at high speed and pressure. However, dams are expensive to construct and have a high environmental impact.

Efforts to harness the low-speed-high-volume flow of naturally-occurring water-ways have not yet proven viable largely due to the following: (1.) the high-cost of the energy-harnessing mechanisms relative to the low quantity of energy harnessed; and (2.) the physical vulnerability of existing energy-harnessing mechanisms.

With this invention, problem 1 is solved with the utilization of large "capture" surface-areas that collectively harness a significant quantity of energy using a potentially cheap mass-produced material. Problem 2 is solved because the mechanism primarily includes flexible and elastic components which are more capable of deflecting or absorbing shocks such as an impacting log or tree branch. A further and related advantage is a more gentle physical interaction with fish and other aquatic animals.