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Energy-Harvesting "Piezo-tree" to Produce Renewable Energy

piezo tree 1 pmPls 69 300x225 Energy Harvesting "Piezo tree" to Produce Renewable EnergyA team of scientists at the Cornell University have developed an energy harvesting “piezo-tree” that uses the flittering of leaves connected to a piezoelectric stem to generate electric energy.

Called the “Piezo-tree”, the system is able to convert the wind energy into electricity whilst remaining light, easily scaled and low-cost. Researchers said that in the prototype, the flexible plate and film are driven to oscillate just as a leaf or flag might flap in the wind. The flapping motion of the leaves is attributed to instability of the aero-elastic system.

The “Piezo-tree” has been made using flexible piezoelectric material Polyvinylidene Fluoride (PVDF), and could withstand unpredictable wind speeds. The basic design is to fix one edge of Polyvinylidene Fluoride element to a cylinder bluff body and leave the other edge free. A vortex shedding will be created when the wind crosses this bluff body and the periodic pressure difference will drive the piezo-leaf to bend in the downstream of the air wake. After rectifying the electricity with a full-wave bridge it is stored in a capacitor and the AC signal is collected from the flapping piezo-leaf, which is working on a periodic bending model.

Due to the weak piezoelectric strain coefficient of Polyvinylidene Fluoride the power level of the preliminary Piezo-Leaf Generator just about 100 pW, being unable to light even a normal LED. Then, scientists tried to put a piece of plastic film to the end of the leaf along the direction of air flow. This change showed about 100 times increase of power in the same condition. However, a series of experiments were conducted using attachments of various flexibility, area, shape and density of polymer and plastic film producing different results in the level of power.

A recent study made by the researchers shows that a particular vertical stalk, horizontal leaf arrangement could increase power output by an order of magnitudes, being a great improvement over current leaf-stalk arrangements. In the future, researchers plan to build plant-like devices with hundreds or thousands of piezo-leaves for practical application. Being a robust and simple scaled device, the “piezo-tree” could be used in a variety of environments, serving as an unique and affective power generator.

[Source: Energy Harvesting Journal]

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Mike is a master student of graphic design and is particularly interested in green designs and green technologies that affect people directly. Besides publishing, he supervises any changes in the site's aesthetics. The current logo is his concept.

Comments

2 comments
jagdish
jagdish

what would be the efficiency of it. can it could withstand in rainy season. how can we improve this model?

earls
earls

This is exactly what I had in mind, but the "leaves" would be solar panels, and it would be great if the "tree" had some sort of storage built in.

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