For many years now, wind has been a source of electricity through big wind mills. Now, a team of engineers are looking at leafless artificial trees to generate renewable power when they are shaken by the wind.

In the study published in the Journal of Sound and Vibration, Ohio State University engineers have discovered new information about the vibrations that happen when wind passes through artificial tree-shaped figures.

"Buildings sway ever so slightly in the wind, bridges oscillate when we drive on them and car suspensions absorb bumps in the road," says Ryan Harne, assistant professor of mechanical and aerospace engineering at OSU. "There's a massive amount of kinetic energy associated with those motions that is otherwise lost. We want to recover and recycle some of that energy."

Harne adds that their project took the opportunity to use all sorts of vibrational energies coming from human, seismic and wind-induced movements that normally occur around us everyday.

To perform their study, the researchers mathematically modelled a tree-like structure and unveiled that despite large and random inputs, it is possible to maintain consistent frequency. They conducted an initial experiment where they created a tree derived from steel beams connected by a strip of polyvinylidene fluoride (PVDF). Then they placed the tree on a bench that produced vibrations and observed that the PVDF generated a voltage of about 0.8 volts from the motion.

The engineers found that objects shaped like leafless trees made from electromechanical materials possess the ability to convert forces like winds into strong vibrations. These vibrations, in turn, can generate electricity. For this reason, the researchers propose valuable applications that serve as an alternative to other renewable energy sources such as solar energy, which is not always available.

One application includes fueling sensors to monitor vibrations that pass through the mechanical structure. The recovered energy will be used to power the sensors, which are designed to determine the soundness and integrity of infrastructures such as bridges or buildings. This means that the whole system is designed to be self-sufficient and able to charge itself using the vibrations caused by the wind or by cars driving across it.

The aim of the study is to convert ambient vibrations into electrical energy. At present, most structure sensors utilize batteries or rely on directly plugging them into power lines. These methods are deemed expensive and unwieldy. With the use of tree-like structures to capture vibrational energy, the sensors could transmit data more sustainable and engineers could produce electricity that is cheaper and more efficient.

Photo : Paulo Valdivieso | Flickr 

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